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

[User]
ELI5: How come when I slap the crap out of a fly, ROCKING its world, but it doesn't get KO'd or get a concussion?

is it because i^am^weak?

[Assistant]
House flies or biting ones that look like them, right?

It's because those flies are tiny, have an armored near-eggshaped shell and are designed to take massive gees of force without damage.

If you hit them in mid-air, your hand is coming at them with a lot of kinetic energy. However, they're very very light and very small besides. This combined lack of mass and size means there's less energy transfer from your hand to them, so the slap transfers very little energy and more or less just pushes their tiny mass out of the way. Contrast that with you spiking a volleyball, which has a lot more mass in total. You'll feel the sting on your hand.

Hit 'em on a hard surface where you're squashing them, and you'll do a lot more damage.


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

[User] ELI5: Why does going outside in the cold make your nose start to run, sometimes immediately?

[Assistant] Because your body naturally tries to warm the air before it gets to your lungs, and it does this by sending fluid to the nose, which is then expelled via snot as the fluid builds up in the blood vessels.


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

[User]
How long does the DNA of viral vector vaccines remain in the host cell and for how long would the cell execute its instructions?

I apologize if this question has already been asked, i could not find any threads or concrete answers about this (or maybe i just didn't understand them :).

So, i've been reading about the mechanism of the new Adenoviral vector vaccines (AZ, J&J, etc). From all explanations i've read, this is my (very simplistic) understanding:

1. Modified adenovirus enters the cell
2. DNA is injected in the nucleus
3. mRNA is "generated" and exits the nucleus
4. Cell starts producing and expressing spike protein
5. Immune response is provoked

What i'm wondering is, basically, what exactly happens with the cell after that:

Does the viral DNA degrade at some point?

Once this DNA is in the cell's nucleus, for how long is step 3 executed?

Since those vaccines are administered in the muscle, i'm guessing it's exactly the muscle cells that get 'infected' and start expressing the spike protein.  And from a very quick search, it seems that the lifetime of a muscle cell is 10-15 years.

I guess a bonus question would be, once the cell expresses the spike protein, does the immune system kill it or persistently continues trying to? In both cases, it doesn't seem like a great deal for a cell that's supposed to live that long :)

[Assistant] I don't believe (and may well be entirely wrong) that the length of time that the viral DNA persists in infected cells is well characterized. Infected cells are likely killed by the immune system before the viral DNA is degraded. In an adenovirus vaccine platform the replication of the virus has been attenuated so that it does not produce new virus. One problem with many DNA viruses is that the viral DNA can be incorporated into the host DNA. This is a low frequency event and the relatively small amount of virus (compared to an active natural virus infection) may make it a very unlikely event. If this does occur, though, a properly functioning immune system would destroy the cell if it caused transformation or if it incorporated and caused the cell to produce viral proteins. As for the loss of  cells due to a functioning immune system - this is trivial. There just aren't enough infected cells to make a significant difference in the tissue.


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

[User] ELI5: How was Bill Gates Windows OS different from Macs and Linux/Unix OS and what made it become so successful?

[Assistant]
You have the order a bit backwards.

The real benefit of DOS, and later windows, was from hardware, not the OS (at least in how it grew to start).

DOS (and then windows) ran on any IBM compatible PCs, which were the standard and produced in huge quantities. Macs only worked on specific Mac-made hardware, and were relegated to a niche market at best.  The sheer volume of IBM compatabile PCs was huge-- so everyone wrote programs for Dos and Windows, and they are pretty user friendly to use, and well, everything worked on it, and everything was made for it.  It dominated the market.

Linux/Unix systems have for the most part once we start the DOS/Windows eras, were relegated to specific, generally specially trained  IT uses, not for the general user.


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

[User]
[Wreck-it Ralph] Would porn games of existing normal games have different 'actors'?

Would there be some pornstar version that looks just like them hanging around in their off hours or would those characters work in both their licensed and unofficial games?

[Assistant] Wreck-It Ralph and Fix-It Felix are separate and distinct individuals from their dopplebangers, Wreck-Tit Ralph and Fux-It Felix. Unless the original manufacturer decides to take the game series in an new/nude direction, any third party knockoffs, porn or otherwise, aren't the original characters.


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

[User]
[Star Wars] What does a droid's 'motivator' do?

Also, what does it mean when a droid has a '*bad*' motivator? Is it easy to repair?

[Assistant]
The motivator converts the energy from the power cells into motion. A droid with a bad motivator can't move right, or can't move at all.

Is it easy to fix?  Well that all depends on what kind of motivator it is (how the droid moves), and what's wrong with it.  Most civilized places in the galaxy you'd just pull it to replace with a spare, and send the defective one back to the manufacturer.


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

[User] ELI5: Why are anthropologists always so impressed about a society having the concept of zero? Why would it be so hard to think of, why do some cultures not develop the concept and what effect does that have on their society?

[Assistant]
It's not that they understand the concept of nothingness that's impressive, it's having the mathematical wherewithal to deal with zero as a mathematical *number.*

For comparison, consider the number (1/2).

The concept of "a half" is extremely intuitive. The relationship between circles and semicircles, lines and their midpoints, symmetry, etc. all rely on "halfness."

...But it's another matter to be able to deal mathematically with questions like "What's five minus a half?" or "What's a half divided by three quarters?"

Similarly, although "nothingness" as a concept is fairly straightforward, zero the *number* has several special properties that are not at all straightforward to deal with. What's zero divided by zero?


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

[User] ELI5, whats the difference between Program Files and Program Files (x86)?

[Assistant] Program Files stores 64-bit programs, Program Files (x86) stores 32-bit programs. The difference is that, amongst other things, the 64-bit programs can utilise more RAM and bus. Hence more efficient programs will be the ones in the non x86 file, especially in more modern, high end machines.


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

[User] ELI5: Why does "&amp" sometimes show up on websites?

[Assistant]
HTML uses characters like ampersand, greater than, less than, etc. in its syntax. So if someone wants to use those symbols in their web page, when they're putting the text in the HTML they need to put "&amp" for an ampersand, "&gt" for greater than, etc. When the browser displays the webpage, it understands to replace those with the proper characters.

The problem is that most webpages now aren't only HTML. There's PHP, Javascript, etc. and all these might not process the text in the same way. So a developer might put "&amp" in thinking that they need to do that, but they've made a mistake and that bit of text is actually not parsed in the same way HTML is so it never gets replaced.


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

[User]
Is the jet engine fundamentally a dead-end?

Aircraft jet engines rely on the combustion of fossil fuels itself as the primary means of propulsion, as opposed to turboprop and piston aircraft in which the turning blades provide propulsion. I can see these blades being powered by electric motors or anything else that might be dreamed up in the future, but there couldn't be such a replacement for jets. Is it inevitable that jet-powered aircraft will be phased out in favor of greener propeller-driven aircraft in the future, however far off that may be?

[Assistant] It's worth noting that something like 85% of the thrust of a turbofan engine comes from the fan, and only 15% from the core (the bit that's burning fuel). Turbofans *could* be made electric in the same way turboprops could be. That said, biofuels, as mentioned earlier, are probably a better way to reduce fossil fuel consumption in aviation, at least in the near future.


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

[User] [Star Wars] is it possible to use the force to shield yourself from radiation?

[Assistant]
Probably. The Force doesn't have an exact set of powers, it flows through everything and everyone, and that includes subatomic particles and electromagnetic waves.

We've seen a Jedi create a shield bubble with the Force that stopped a lighstaber strike (Fallen Order), and in Legends, a Jedi can use the Force to protect themselves from poisonous gas (KOTOR 2). Neither of those are exactly what you're asking, but both show that you can isolate yourself from external non-solid harm even if temporarily.


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

[User]
ELI5: Why do we sometimes violently jerk awake just as we are drifting off to sleep?

Sometimes, just as I am drifting off to sleep, I will suddenly and violently jerk awake (think flailing legs and arms, gasping for breath, scared or disoriented). What causes this? It occasionally happens from a deep sleep as well. I assume there's some kind of physical explanation.

On a side note, this also happens to me the few times I've been in the hospital and had morphine.  So I've always wondered what physically causes this kind of sleep disturbance? Blood flow? Brain wave disruption?

[Assistant] Great question. This is called a hypnagogic jerk. There is no real explanation to the phenomenon but its our body reacting to stimuli while transitioning into sleep. This stimuli can be external (sound, feeling, etc.) or from the first period called the Alpha/Thera stage where you see images before deep sleep due to increased brain activity. It can also be caused be going straight to REM and partially dreaming. It's thought that caffeine or any uppers will cause this more, but there isn't enough studies on the topic.


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

[User] ELI5: Why does testosterone production vary much between individuals?

[Assistant]
Its a hormone. Hormones are signaling mechanisms. Basically they are designed to vary.

This is like asking why certain pianos emit different notes. Its because the nature of a piano is that it has many notes. The whole function of it is to provide that variation.

Like a piano with 88 keys, a hormone is a signaling mechanism with many varying levels of activation.

In this way, testosterone level is analogous to:

* the speed of a car
* the height of the tides
* the brightness of a variable switch light
* the setting on a thermostat

And given that context, the reason testosterone levels vary between individuals is that those individuals have provided different amounts of inputs into the processes that determine testosterone levels.

For example someone who has just done a bunch of sprinting will have higher testosterone than someone in the same overall health whos been sitting still. Someone whose muscles are bigger will have higher testosterone than they would have if, all other things being equal, their muscles were smaller. Just in the same way that a car where the gas pedal has been floored for the last ten seconds will have a higher speed than a car where the brake has been pressed for the last ten seconds.


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

[User] [MCU] Why was Tony so angry and offendedthat Steve suggested/compared them to soldiers in Avengers?

[Assistant]
For one, because he has already emphasized he is not there to follow Fury's orders (which he again restates in the rest of the quote).

Another reason is likely do to the fact Tony explicitly stopped making weapons of war.

Also he's a little frustrated trying to argue his points with Cap who seems to see everything through the eyes of a soldier.


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

[User]
Who was the last notable autodidact philosopher? Can you recommend any writings on the professionalization of philosophy?

I wouldn't call Wittgenstein an autodidact, he didn't go to university, but he didn't need to. He came from one of the best families in Europe and was taught at home by private tutors.

As for the professionalization of philosophy  and other intellectual disciplines like literature and the fine arts  there was once a time when to be a philosopher meant being a man considered "the questions" and shared their thoughts with the world by some means. Very few of them were educated to be a philosopher and those that were, weren't trained at a university, they were instructed as protgs of the thinkers of the day, the education of Plato and Aristotle by Socrates is a famous example. Those philosophers who did have a formal education, weren't educated to be philosophers, they were given a basic education and taught how to read and write in their language and Latin or Greek (to read the Bible), along with things like mathematics.

I think that this kind of professionalization is detrimental, it's important to be properly trained and certified if you're a doctor or lawyer whose actions can have a profoundly bad consequence for others if done wrong, but for something like this I would suppose that there plenty of people who have interesting things to say from a philosophical perspective, but if they don't have a postgraduate education in the field that they're writing in, no publication will take them seriously and they'll be ignored. Sometimes people who are very talented and have important things to say, just aren't "school peop." In literature it's the same thing, a lot of great poetry and prose is confined to perpetual obscurity on a blogspot page, because a poetry anthology or publisher of "serious literature" won't even look at their work if their resum doesn't have an MFA on it.

Those are my thoughts on professionalization, but what I'm really interested in, is what philosophers themselves have to say on the situation.

[Assistant]
The comparison of Plato and Aristotle to autodidacticism is quite inapt. They spent years in extensive philosophical education. That it was not in an institutional structure identical to that found in much of the world today hardly makes it comparable to autodidacticism.

Neither has philosophy ever meant merely "being a man [who] considered 'the questions' and shared their thoughts with the world by some means." People often point to the etymology of the word 'philosophy' to support this view of the discipline, but etymology is not a reliable guide to the history of institutions, and in any case what formative figures like Plato and Aristotle meant by 'wisdom' in this context is something much more specific and technical than is imagined on this etymological argument.

While there are some senses in which different periods have seen a professionalization of philosophy, the idea that philosophy has in recent history gone from its previously normal state of being the domain of autodidacts who just consider questions to the domain of people with formal training in the field is premised on what is simply a fictional account of the history. A systematized course of instruction was already a feature of the Neoplatonic tradition in late antiquity, and the institutional background and significance of the university is a development of the high middle ages.

The nature and significance of professionalization in philosophy is a matter meriting attention, but just for this reason our attention to it should be placed on a careful accounting of the relevant facts.


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

[User] ELI5: Why are all external body parts, like eyes or ears, symmetrical along the spine but some internal ones, like the heart, are asymmetrical?

[Assistant]
It has to do with embryology (how the embryo develops into a human).
An embryo starts out as a flat disc with 3 layers of cells and then "folds" in on itself (imagine wrapping a burrito).

The innermost layer forms a tube, which will develop into the internal organs, and the outermost layer forms your skeleton, bones and connective tissues (pretty much everything that isn't your organs)

The outer layer develops symmetrically about the midline. 2 eyes, 2 ears, 2 arms, 2 legs. Interestingly, your brain is also symmetrical about the midline (although the right and left brain do have different functions)

As the inner layer of cells (the tube) it becomes squashed against the walls of the body cavity. This causes the tube to twist and bend as it develops. Eventually different parts of the tube differentiate into different organs. The lungs, liver kidneys and spleen branch off the midline. The gut does a whole bunch of Gymnastics. Interestingly the "start" and "end" of this tube (the mouth and anus) ARE symmetrical.

The heart is a good example of this. It starts out as a symmetrical tube, but bends and folds as it develops, ending up in the 4 chambered configuration of a mature heart.

The reason the outermost layers are bot symmetrical is partly because they are not space restricted like the internal organs.


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

[User]
ELI5 : why does the brain sometimes take a moment to process words?

Ive noticed, for years, when talking to people, if I say something, at times theyll say what? like they didnt hear me. Then reply accordingly without me having to repeat anything. It happens to me too. So, what is the delay and why does it take a split second to process?

[Assistant] Basically, at the same time the person said "what?" because their conscious mind didn't quite get it the first time, their brain was still analyzing the sound, and right after they said "what" their brain automatically listened to the short term memory of the sound a couple more times and eventually figured out what the words were.


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

[User] ELI5: How can companies like Dole, grow something like Bananas halfway across the world, process them, ship them, and then sell them for less than a dollar a pound and make a profit?

[Assistant]
There are a couple of reasons.

1) By growing their produce in countries where the cost of living is low they don't spend very much on wages for people who work their plantations.

2) many times those same countries have far lower standards in construction and safety, so they spend as little as possible in those areas.

3) size. A company like Dole has a massive market share so even if they only make a little off each banana they sell so many of them that it adds up to huge profits.


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

[User] [EL5] How the fuck does shazam work?

[Assistant] Shazam has a catalog of many, many songs. Each song has its own unique "fingerprint". This fingerprint is calculated using special mathematical equations specialized for turning sound into an identifiable number. When you send a sound clip to Shazam for identification, it takes the sample, applies the math to the sound to find its fingerprint, then looks up the fingerprint on their database for a match.


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

[User]
[Doctor Who/Loki] What would The Doctor think of He Who Remains plans?

I was randomly thinking of this today.

Even though it came out a while ago, spoiler alert for Loki!!

Anyways, we all know The Doctor. He/she has been at the beginning of time, the end of time, they re-created the universe, they traveled outside the universe. They met multiple versions of themselves through their own time stream. The Doctor definitely has a complicated relationship with time.

He Who Remains is trying to force all time streams into one single one so his variants dont start a Multiversal War.

How would The Doctor react to the plan by HWR? HWR is just as intelligent as the Doctor. Also, would he have tried to stop Sylvie from killing HWR??

[Assistant]
The Timelords also carved a single sacred timeline out of the whole multiverse. So The Doctor's biggest shock would be that he has (once again) managed to breach the dimensional barriers and end up in a different cordoned off timeline. It's supposed to be impossible, and he's done it at least half a dozen times at this point...

After that he'd probably eventually see HWR's methods with the TVA and declare them unacceptable, and by *{insert science we don't understand here}* would cause everyone in the TVA to regain their true memories.

As for Sylvie killing HWR - that depends on where in The Doctor's timeline this is happening. If it's doctor 9+ they'd almost certainly try and stop her - but some of the earlier doctors would have actively approved, or even killed HWR themselves.


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

[User]
CMV: There is no empirical support for the Cancel Culture panic

It has become dogma among pundits and regular people on both sides of the political spectrum that Cancel Culture is a new and grave threat to society. The claim is that debate has become less open in general and that free speech is under attack because of the Cancel mob.

With the rise of social media amplifying more voices with every passing day, I can totally understand how people have come to this conclusion. What I dont see is any empirical support for the notion that debate is less open or speech is less free. It is especially strange to see that the panic around it is perhaps most acute among the same people who regularly talk about how we need to return to facts and logic rather than feelings in the discourse.

How are we measuring the openness of debate? If we claim it is less open, when was it more open? Is there any proof that cancellation didnt happen then? Basically- Is there any evidence beyond feelings and platitudes that speech is actually less free now than in the past?

I havent seen good answers to any of these questions, but I fully acknowledge its possible that they exist and I simply havent found them. So my challenge to the subreddit is to show me that evidence, and give me some indication beyond examples and vibes that modern cancel culture actually represents something new and threatening.

[Assistant]
there are numerous cases of people getting fired or forced to resign due to relatively innocuous actions, such as a researcher tweeting about a study on how violent protests affect voting patterns, or the opinions editor of the NYT letting a Republic senator put out an op-ed regarding how military may need to be brought into quell unrest in American cities.

it's hard to imagine those things happening at any other point in our lifetime.


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

[User] ELI5: The method to the madness of country codes (+1, +44, +358 etc). What's the actual pattern, if any?

[Assistant]
There was a bit of politics to the pattern. 1 for the USA down to 7 for the USSR at the time with other areas being given intermediate numbers. Africa is 2, Europe is 3 and 4, South America is 5, Australia is 6 and China is 8.

Individual countries within those are split further. They're normally given a smaller number based on the size of the country. USA's country code is 1 for example, UK is 44, and Iceland is 354.

This is because there was an agreement to try and keep international telephone numbers to eleven digits or less, so the smaller a country is, the fewer digits it needs left in order to be able to dial every possible number in that country, including all the local regional and area codes. So the bigger countries need more spare digits, hence the USA having just 1.

Everything sort of fit over the years around that one concept.


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

[User]
ELI5: Why does it take youtube a long time to load a video when going frame by frame [using , or . ] but not when playing the video normally?

You would think that a video would take longer to load than an individual frame but it's the oposite on youtube.

[Assistant]
Inefficient web-based code. It seeks back to the last keyframe and decodes the preceding group of pictures until the required frame.

Video compression works by saving differences between frames. At certain intervals there are independent pictures (keyframes), usually at scene changes. But in case of YouTube this interval is fixed to 5 seconds. Direct seeking is only possible to keyframes. You can see that frame-stepping is faster at the start of a video and at certain points.

A normal video player will maintain the current state and is able to seek forward quickly. Seeking backwards is almost always slow, unless the required frame has been cached in memory.

You can have more responsive control over video playback if you download it with YouTube-DL and use a native media player. Holding the frame-step key in MPC-HC or SMPlayer plays back at full speed on a low-power PC.


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

[User]
[Bioshock] I want to get invited by Andrew Ryan to live in Rapture, what qualifications would I need?

 I want to get invited by Andrew Ryan to live in Rapture (prior to it's downfall), what qualifications would I need? What would the invitation look/be like?

[Assistant]
Rapture was designed as an Objectivist paradise, freeing the industrialists, scientific pioneers, and other captains of industry from the shackles of the Statist and socialist governments of the surface world and allowing them the pure economic freedom of a true Capitalist society.

While wealthy CEOs and trade tycoons would often be forwarded a relatively simple paper or in-person invitation to make their way by private aircraft or yacht to an unassuming island in the north Atlantic, it is likely that those unfortunate minds who were held captive by oppressive parasite governments and lacked the material funds to charter their own transport (Suchong, Tenenbaum) were offered the opportunity to escape via Ryan's personal cruise liners.

The grand majority of the population of Rapture were likely extended the offer by their employers on the surface. While wealthy CEOs and pop artists received personal invitations, they were offered several ancillary summons in order to establish their trade in Ryan's bold new utopia.

It is likely in your best interest to be in direct need of your employer; whether that be the top engineer in your field, in a supervisory position of direct need to your company, or in some other way indispensable to the everyday operations of your employer, or to be in such personage's direct family.

Remember, the Great Chain is guided by our hand. Though you might not be a world-renowned pillar of industry, or the shining intellectual giant on the breaking edge of scientific breakthrough, or an avant-garde virtuoso breaking down society's shackles of free expression, somebody has to scrub the toilets too.


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

[User]
ELI5: Does dish water need to have bubbles it in to clean dirty dishes?

For as long as I can remember, first my parents, then my boss at the local pizzeria I worked at, then my wife kept insisting that once the bubbles are gone from the dish water it needed to be changed because the dishes could no longer get clean.  I always argued that made no sense to me because I'm not cleaning them with bubbles.

Is there any truth to this or is this just a common myth?

[Assistant]
Bubbles aren't needed, but the stuff that is needed happens to make bubbles.

Soap molecules are weird -- one end is very attracted to water, and one end is very repulsive to water. Picture a few molecules forming a ring around some dirt, with their repulsive ends picking up the dirt, and their attractive end helping it dissolve into the water.

Of course, it doesn't have to capture dirt this way. It can also capture air. Because the attractive end is so attractive to water, it creates even more surface tension, making it very easy to bubble.

When you run out of bubbles, that means the amount of dish soap left in is very low. It might not quite mean that there's no washing power left, but there's at least very little.


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

[User] How exactly do measle viruses infect the T-cells?

[Assistant]
Once the measles virus gets onto the mucous membrane, it will infect epithelial cells in the trachea or bronchi. It uses a surface protein named hemagglutinin (H protein), to bind to a target receptor on the host cell, which could be CD150, aka signaling lymphocyte activation molecule or SLAM, which is located on immune cells such as B or T cells. Once it's bound, the fusion/chimeric protein helps the virus fuse with the membrane and eventually get inside the cell. The virus is a single-stranded negative-sense RNA virus which means it first must be transcribed by RNA polymerase into a positive-sense mRNA strand.

Next, it's ready to be translated into viral proteins, wrapped in the cell's lipid envelope, and sent out as a newly constructed virus. In a period of days, the measles virus will spread through the local tissue and will be picked up by dendritic cells and alveolar macrophages, and carried from that local tissue in the lungs to the local lymph nodes. It will then continue to spread, eventually getting into your blood and spreading to even more long tissue, as well as other places such as the intestines or brain.


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

[User]
ELI5: How did so many different currencies all come to use the dollar sign ($)?

A lot of other currencies seem to have symbols specific only to themselves (, ), so I have been wondering how it is that the dollar sign is common to so many different currencies worldwide. Off the top of my head, I can think of pesos, USD, CAD, and AUD. I'm also interested in why more than one country calls their currency "dollars" even though USD, CAD, and AUD are very different and have different values in the international exchange.

[Assistant]
It wasn't really until the 1648 and the signing of the Treaty of Westphalia that the modern concept of a nation state with fixed borders really started. Before then unless you were an island like the UK then your borders shifted as kings died and neighbouring countries extorted taxes from whatever territories they could.

So without different countries money was just some token of value that people only trusted to some extent. If it was a gold or silver coin then it didn't really matter which king's face was on it, it still had value.

The town of Jchymov in Czechia had a silver mine and for centuries minted a coin from this silver, the German name for Jachvmov is Joachimsthal (Saint Joachim's Valley), the coins were known as Joachimsthallers, or thallers for short which would be roughly pronounced as 'dollar'.

For four hundred years the thaller or dollar was a popular coin who's value was trusted all over Europe and the known (western) world.

When nation states became established, they created their own coins and would name them similarly, the American dollar, the Canadian dollar, etc.


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

[User]
Can photons move slower than the speed of light when near a black hole?

We know photons always move at the speed of light.

However my theory is that when a black hole is made there is a point where 1 photon is still going away from the black hole and the other one will be sucked in by the black hole. So the last photon was moving away from the black hole but the force of gravity massively increases and the photon will be forced to go in the direction of the black hole.

What if all forces on that photon pull it the exact same amount which means there is no side besides up or down to which the photon can move. The black hole pulls harder than the rest of the sides of the photon which means the photon can't bend in any direction. The photon will then be forced to slow down to 0 and then ramp up again to the speed of ligh towards the black hole.

I hope you can understand me as this is quite hard to explain for me since i'm not natively english.

[Assistant]
The **local** speed of a massless particle is always c. So if you're observing the motion of a photon from very close by, you'll always see it moving at c.

However if you're watching the photon move from far away in curved spacetime, the rate at which its position changes in *your* coordinate system doesn't have to be c.

The classic example is the speed of a photon moving radially near a Schwarzschild black hole.

It's speed in the Schwarzschild coordinates of an observer at infinity is:

dr/dt = (1 - 2GM/rc^(2))c,

where G is the gravitational constant, M is the mass of the black hole, r is the radial coordinate, t is the Schwarzschild time coordinate, and c is the speed of light.

You can see that as r goes to infinity, dr/dt goes to c. But as r goes to 2GM/c^(2) (the event horizon of the black hole), the speed goes to zero.

So an outside observer will never see an inwardly-traveling photon cross the horizon of the black hole.

A similar calculation can be done for a photon moving in the azimuthal direction rather than the radial direction.

So yes, a photon will move slower near a black hole if you watch it from far away.


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

[User] Is there such thing as an allergic reaction to alcohol? Are some people's immune systems incapable of managing the stress that alcohol consumption puts on them?

[Assistant]
I've never heard of an allergy to ethanol. Some people are alcohol intolerant, which means they have a genetic deficiency of an enzyme known as alcohol dehydrogenase. If someone does have a real allergic reaction while drinking alcohol, it is probably a reaction to something else in the drink that was added for flavor, and not the EtOH.

The idea of an alcohol "allergy" probably comes from observing the symptoms of alcohol intolerance, which include skin turning red and a runny nose. These are symptoms that are generally associated with real allergies, so that's probably where the mix up originated.


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

[User] ELI5:Why do large companies advertise when they have nothing that can be purchased by normal consumers? (i.e. Boeing)

[Assistant]
Primarily, to keep their name in the industry, and to attract employees.

Boeing also manufacturers trains, likely a larger part of their business financially than the aeroplanes. By keeping their name up there, cities are more likely to buy Boeing trains for their subways.

Simply: Just because they aren't on the "normal consumer" market doesn't mean that there isn't a "massive consumer" market looking for their products, and advertising doesn't know borders.


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

[User]
Why so many neurons to manage limb movements in humans while small animals get by with so few?

 A large portion of our already oversized brains is used for coordinating our limbs. This makes some sense since there is a lot of "math" that needs to be worked out for the inverse kinematics of something as simple as buttoning a button. But how do small animals, like spiders, manage complex tasks with comparatively few brain cells. Brains are costly in terms of metabolism and evolution is not wasteful. So I am assuming there is a reason why we require literally billions of CNS neurons to coordinate our limbs while spiders get by on just tens of thousands.

[Assistant]
Your muscle cells can only fire at maximum force (they are either off or fully activated), and cannot be actively shut down - you just have to wait for relaxation after the nerve stops firing. As a result, to have any sort of subtlety, we have tens of thousands of muscle cells in a muscle, with a few dozen per nerve, so we can only activate a small fraction of the total muscle mass to get a small force.

Arthropod muscles have graded responses where increased nerve stimulation increases force, and can respond to inhibitory signals to decrease force.  As a result, they can get subtly graded force responses from just a few (larger) muscle cells and neurons.

Why is each the way it is?  No idea.  Both diverged early in animal evolution, shortly after nerve and muscle became different tissues, so most likely each just hit upon a different solution to neural control and stuck with it.


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

[User] [Marvel] Could Galactus visit Asgard and feast upon it? If he could would it be filling?

[Assistant]
He has the ability to feed on it. And it would be filling.

But even Galactus has limits, and the combined might of Asgard would defeat him. Odin himself would be able to hold him off alone for some time (he would ultimately fail, though)


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

[User] [Marvel/DC] What street level villains could become national/global threats if they just applied themselves?

[Assistant]
Electro.

In principle, he's powerful enough to be an enemy of the avengers, and has fought them successfully until Thor's specific power to affect him stopped it. He has control over electricity and near-infinite electrical charge, and that's a *very* useful ability. He could potentially reach magneto-level power and become a very serious threat to the world.

But he's an idiot.

He has all this power, and he genuinely can't think of anything smarter then "shoot lightning bolt at spiderman". He could take the avengers one on one, if he had any creativity or imagination beyond "break into bank vault" over and over again.


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

[User]
Papers to write, but I hate writing papers. Does anyone have any recommendations for overcoming my procrastination on writing journal articles?

I'm a decently published author at this point (mid-career), but I'm terribly slow at the process.  I have about a dozen papers/manuscripts in my backlog that I think I could finish.  Papers just take forever for me to write.  I understand the process, but every time I have an opportunity to work on them, I just find something else to do.

I could use some advice beyond "make an outline and just fill it in" or "start with the figures and tables, and then do the materials and methods section" ... how did you overcome scientific writer's block?

[Assistant]
1. Write first thing in the morning after breakfast. DO NOT CHECK YOUR EMAIL. DO NOT OPEN YOUR OFFICE DOOR. DO NOT CHECK YOUR EMAIL. Did you hear the thing about the email? Don't even go fucking near it. Write on something with no internet connection if necessary.

2. Write for 90 minutes every morning before anything else. Just an hour and a half. Then leave it at that. Do your other shit and maybe come back to it later in the afternoon. But that 90 minutes is the best writing time of your day. If you can absolutely shred this time then you will be more productive than if you cleared an entire day and just dicked around.

3. Write with others. You'll police each other.


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

[User]
[ATLA]Can the average firebender touch hot metal without being burned?

In the episode where Iroh is captured by Earthnebders he is able to heat his manacles until they are red hot, burning the guard who touches it but not himself. Are there any other examples of firebenders touching hot objects without being burned?

[Assistant] I think it's an intent thing. A forever can touch an object he is actively heating without being burned, but cannot touch an externally heated one. This would explain why Iroh could heat the cuffs, but Zuko could be burned by his father or the prison lake.


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

[User]
What about deep breathing makes us lightheaded?

As in, how does deep breathing cause lightheadedness? If it's simply "Too much oxygen" what about all that oxygen results in feeling lightheaded?

What mechanisms are at play/ what's going on?

[Assistant] Hyperventilation removes more CO2 from the blood than is being released into the blood via cell respiration. This increases the pH of the blood, a condition called alkalosis, which in turn causes blood vessels to constrict, reducing blood flow. Alkalosis also reduces the amount of freely ionized calcium in the blood, which is essential for proper nerve functioning, and which also causes blood vessels to constrict, reducing blood flow to the brain further, which makes you feel lightheaded.


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

[User]
[MCU] Why doesn't Tony Stark always use his suit like a drone instead of actually getting inside it?

I was re-watching Iron Man 3 and saw the scene where he rescued a dozen falling people and the surprise at the end was that he wasn't actually in the suit but controlling it remotely.

So why didn't he keep that up in subsequent movies/events?

He does get banged up when he's in the suit so why not always control it like he did in Iron Man 3?

[Assistant] He's a control freak. Tony Stark COULD pilot it remotely, but he is paranoid that the microsecond of lag between him and the suit could mean the difference between life in death in many scenarios, and likewise, he just likes wearing the suit. It's comfy and makes him feel powerful.


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

[User] Eli5: Why does the mixing of alcoholic beverages seemingly get you drunker quicker/why is it seen as such a bad thing?

[Assistant] It doesn't really, it's just easy to physically drink more when you are mixing it up. It seems weird to drink your 5th vodka but if you have drank a bunch of different stuff you don't notice you have drank so much. Food is the same way, People will notice they are eating a ton if there is just one food out, but if there is a selection they will eat one of each and not notice how much they have eaten. Like people will realize eating 5 hamburgers is excessive but if you go to a cookout with hamburgers and hotdogs and steak and chicken and kebobs and stuff people will eat em all.


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

[User] Is there an agreed-upon, independent measure of how strong a password is, regarding crackability? Every website thinks differently about how strong my passwords are. (Not sure if right subreddit but it's CS so I hope yes)

[Assistant]
It depends on whether your password is *actually generated randomly*. *If it is*, then the calculation is just

number of characters * log base 2 (the number of possible characters that we can choose from). This gives us the workfactor for cracking a password in bits. So a 10 character long *random* alphanumeric password would have a workfactor of:

10 * log base 2 (62) = 59.54 bits of entropy. Which would mean that on average, about 2^58 trials would be needed to break this.

For passwords that are *not* chosen randomly, this is harder to compute, and depends on the characteristics of the language that the password is generated from. The rule of thumb is that for English passwords, the first character has about 4 bits of entropy, the second has about 2, and each subsequent one has 1 bit or so. The amount of entropy per character in English is about 1 bit when we're looking at regular, uncompressed data.


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

[User] ELI5: Why do European countries have many more manual cars than the US?

[Assistant]
Not so much now, but traditionally, manuals delivered a more performance from a smaller engine and thus better fuel efficiency.

Fuel is generally much more expensive in Europe (even double the price) so fuel efficiency was important.

In addition manual drive chains tend to be longer lasting and easier to maintain, making them popular especially in eastern Europe where incomes are lower.


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

[User] If planes can take off in one lane airports, why do they bother wasting time taxying around based on wind direction before takeoff.

[Assistant]
Imagine a calm day with no wind. If an airplane needs air going 150 mph over it's wings to generate lift, then the plane needs to go at least 150 mph to take off.

If the plane takes off into a head wind that's blowing at 25 mph, then the plane's ground speed only has to be 125 mph before it can take off. If the plane attempted to take off with a tailwind of 25 mph, then plane needs a ground speed of 175 mph to have 150 mph wind blowing over the wing.

This is the same reason aircraft carriers have to turn into the wind when planes are attempting to take off or land. The wind helps increase the speed of the air going around the wings.


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

[User]
How can the diameter of the Universe exceed its age?

The Universe is 13.8 billion years old and the observable Universe is about 93 billion light years across. How is this possible?

If I had to guess, I'd wager that the Universe must have expanded faster than the speed of light at some point in its evolution. I'm not sure if that makes sense though, and details would be lovely.

[Assistant]
I think the most concise answer is "expanding faster than light" means nothing since the amount of expansion does not have units of velocity.

The amount of expansion from time t to today (t_0) is given by the ratio between the size today and the size at time t. This is a dimensionless ratio and cannot really be compared with c.

Now, you can take two specific points (for example, here and a galaxy currently at the edge of the observable Universe) and you'll find that their distance increases, indeed "faster than light". But this is not an actual speed you can measure, it's just a coordinate speed in some coordinate, it is not physically meaningful. It's just that space inbetween them is getting bigger.

If you were to perform a measurement of the galaxy's velocity, you would actually need to be close to it (you can only perform local measurements). You will always measure a speed less than c.

At any given time, in any possible expanding Universe, there are galaxies far away enough that the distance between them increases faster than light.


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

[User]
Advice for a young professor dealing with academic burnout and needing to revive a flagging career?

I started this job four years ago and they have been really hard ones for me. Between the demands of my academic job, a difficult department/institution, and some really tough family stuff, I am just wrung out.

I am the only child of elderly parents who have had a continuous set of alternating health emergencies over the last four years. Two or even three times a year a parent required a long hospitalization and a complicated recovery that I had to take care of. A year ago my father passed away leaving the control of everything in the family to me (my mother has dementia among other chronic issues). Settling his estate and making sure my mother is cared for has been a very big job (not to mention dealing with the grief when I have a bit of time to do so, we were very close).

Superficially, my department was understanding, saying to take the time I needed and family comes first, etc. In reality (and perhaps understandably), though, they saw my reduced productivity and attendance in the department and were not pleased. I just can't be the high-performing academic they want. I kept thinking that after each crisis, things would smooth out and I really get things done, but then another would come up. I've had a few painful and frank conversations with my chair and the provost. I think they could have been more supportive, but they weren't, and it's better not to think of what could have been and concentrate on the regular situation.

I've managed to do all the service and teaching required, but that is not valued much. I tried to revive my research many times with collaborations and taking on new students. None of the students have worked out, they learned a lot but I ended up needing to redo all their work. (This could be my fault as well, not supervising them enough.)  I have a lot of great collaborations, but that work has also been massively disrupted by my family issues, and they have lost patience with me (also understandably). Just down to it, much of the issue is that I do not have the energy and focus research requires.

I need a new job, I just cannot perform at the level needed here, but I find myself feeling too burned out to go through the faculty job search process again. Also, I have not published in *years* and my last grant ran out in 2017, I have not had a new one (applied for a couple but no luck). My CV looks pretty sad right now. I should be manuscript-writing my ass off, job-applying my ass off, grant-writing my ass off, but I find I can barely get four hours of work done in a day.

(As an aside, I'm not alone in all this. I have a husband, but he actually has had almost identical issues with his family and is also exhausted and grief-stricken. Additionally, he hates his job, whereas for me it feels more like my job hates me. I have seen a therapist and a psychiatrist. I am on anti-depressants and though I am not really depressed I think it maybe helps somewhat. They have both been sympathetic and helpful in some ways, but the consensus among them is that things are just really hard and my issues are a normal response to continuous stress.)

Any advice on how to recover and revive?

[Assistant] Is anything you're dealing with covered under FMLA? A colleague of mine stopped the clock for reasons of family disaster, and made tenure in the end. She did however go a year without pay, and had benefits through her spouse, so it may not be viable. (This assumes you are in the USA, of course.)


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

[User] What happens to the parts of the brain which control amputated body parts?

[Assistant] They exist, and can even be "tricked" into thinking an arm is still there which is basically phantom limb syndrome; it's also the basis for some robotic prosthesis which wouldnt work if the brain didnt retain those faculties; there are some local neurons that likely need to be developed, but the brain remains entirely undisturbed.


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

[User] [wrestling] Why can't some people see John Cena at times?

[Assistant] When the glorious GOD-EMPEROR of mankind created his twenty primarchs, two vanished, never to be seen again.  One was lost in the warp for all time, a champion of chaos that will never be redeemed.  Another was flung back in time to the 2nd millennium.  Cursed with powers beyond his understanding he seeks the attention he so deeply craves but fears that people will take him as a witch and fiend.  Thus he only enters competitions people assume are full of tricks and distractions, lacking any true magic.  AND HIS NAME WAS JOHN CENA!!!


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

[User]
[DC] How do Atlanteans move so fast in the water?

Have you ever tried to punch someone under water? The water dampens (pun possibly intended) your movements. Every time I see an Atlantean fight under water, they move like they're in air. How?

[Assistant] Atlanteans are incredibly strong. Strong enough to move that quickly under insane pressures. That's really all there is to it. They move faster and are proportionately stronger above land, but even below they're pretty terrifying.


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

[User]
ELI5: Why does my mouth taste so fucking awful when I wake up?

Even if I brush my teeth just before I go to bed, why does it taste so horrible when I wake up?

[Assistant] Brushing only removes the build up of plaque, food, etc on your teeth/gums/tongue. The bacteria is there regardless. When you sleep, breathing and reduced saliva production increase the levels of bacteria in your mouth. These bacteria aren't harmful, they just leave their waste in your mouth and that's what tastes so bad.


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

[User] [X-Men] If Magneto's helmet, which can be made of any strong metal Magneto happens to have on hand, prevents Professor X from reading his mind then why is Wolverine, who has an adamantium skull, prone to Professor X's telepathy?

[Assistant] The helmet isn't just "any strong metal Magnet happens to have on hand" but was especially designed in some way to do so.  We're not sure how it works exactly, but not any slab of metal will work unless designed to do so.


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

[User]
CMV: Bicycle riders who ride in the street should be required to obtain a license much like cars and motorcycles

I believe that bicycle riders should be required to obtain a special license to ride in the street. The license should be much like the M1 a motorcycle rider must obtain. This is mostly due to my belief that if they are on the road, they should be required to know all the road laws and rules.

The Process I propose all bikers should have to go through would be similar to the process for a motorcycle permit.

* Bikers should  have to take a written test that will quiz them on the rules and laws of the road, including those specific to bicycles. Hand signals etc.

* Bikers should have to have a 6 month permit if under 21, which will restrict their night riding.

* A riding skills test testing their capability to ride a bike and their ability to do everyday maneuvers.

* Bikers must be at least 16 years old to ride on the road

With these laws I think the roads would become a much safer place for cars and bikers, and many laws will be cleared up for bikers who don't understand the law.

Any funding earned through this program could also benefit bike programs like the implementation of bike lanes.

[Assistant]
How the hell are kids under the age of 16 supposed to get around town in your scenario?

A car is capable of easily inflicting great bodily harm, death, and extensive property damage. A bicycle is not. There's a compelling state interest in regulating cars and drivers that simply does not exist for bicycles.


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

[User]
ELI5: What happens to an eyeball after it's removed from a body and loses its moisture?

Sorry if this is gross, I've just always wondered and can never figure out how to Google this. I never participated in dissections and I don't hunt so I've never interacted with an eyeball apart from putting contacts in.

If you took an eye out of a person or animal (not suggesting this at all) and just set the eyeball on a table, what would happen to it? Would you have an eyeball raisin after it's all dried out, or a pile of eye dust, or just nothing?

[Assistant] Well, it would definitely depend upon the environment around the eyeball, but since you're particularly curious about it being dried out; in an arid environment (say under a heat lamp or something) yeah, it would turn into basically an eyeball raisin. But under most conditions, it'd basically just eventually rot, turning into a dark goo as it decomposes, like the rest (mostly) of the organs.


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

[User]
Why do LCD readouts, such as digital clocks, appear to "bounce" when you view them and chew at the same time?

I hope that others have also experienced this phenomenon. I could understand that the force of our jaw is enough to cause our eyes to vibrate somehow, but why is it so pronounced in these circumstances?

[Assistant]
Here's the key; only one segment of the display is on at a time. This is because only a fixed amount of power is available to the display, so the number 8 (made up of 7 segments) would otherwise be dimmer than a number 1 (made up of 2).

They cycle through so fast that they appear to be continuous... but when your eyes are moving at a relatively high speed, the segments are in relatively different places. Since they're intense and separate, they appear to jiggle more than the surroundings.

If the display were moving in a straight line very fast, you would see the effect there as well.


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

[User] ELI5: What is smoke made out of that makes ham and fish taste better?

[Assistant]
Hardwoods (the type used for smoking ham, fish and other foods) are made up mostly of three materials: cellulose, hemicellulose, and lignin.

Cellulose and hemicellulose are sugar molecules which, when burnt effectively caramelize to produce carbonyls. These provide most of the color components and sweet, flowery, and fruity aromas.

Lignin also produces a number of distinctive aromatic elements when burnt, including smoky, spicy, and pungent compounds such as guaiacol, phenol, and syringol, and sweeter scents such as the vanilla-scented vanillin and clove-like isoeugenol.

Since different species of trees have different ratios of components, various types of wood impart a different flavor to food.


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

[User]
[Pokemon] How bad does something need to get before The Elite Four or Champion are brought in?

In Black and White, it takes an entire cult rising to power and overthrowing the Champion and even then, only the Gym Leaders get involved. The Elite Four doesnt do jack shit. And in most other games, world-destroying, legendary threats are reserved for ten year olds with about 7 badges. So why does nobody think Hey, you know those four Elite Trainers, plus the Champion, that weve all collectively decided are the best of our region? Shouldnt they be the ones stopping this thing and no Little Timmy with his Empoleon?!

[Assistant]
The E4 and the Champion are NEVER brought in.

SOME Champions care enough about their region to be doing their own investigations - Lance, Steven, and Cynthia were all independently investigating what was going on.

In Lance's case, he actually discovers the Team Rocket plan in Mahogany Town and recruits the player to help. Then the player beats him to Goldenrod and ends the crisis. Lance was never called in, he just identified the threat and stepped in on his own because he's a hero.

Steven seems like he may have been partially called in by his friend Wallace when Team Magma/Aqua were going nuts. But since the player was the one who held the red/blue orb they had to go in and finish the crisis caused by Groudon/Kyogre. When Wallace called Steven, it was potentially world-ending.

Cynthia was investigating what was going on in Sinnoh and is there with the player during the climax at Spear Pillar. She wasn't called in, Team Galactic was just pretty loud about their plans and she figured it out. Like Lance, Cynthia is a self-motivated hero.


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

[User]
ELI5: Why do unoccupied houses fall apart?

Why is it that, in houses left alone, things like the stairs rot and fall in?  As opposed to houses where people walk up and down the stairs all the time, but don't have to constantly repair them?

[Assistant]
Wood in old houses left alone won't rot on their own.  They need stuff like broken windows to let in moisture, burglars to steal the copper pipes and get stuff wet, and melting snow that has blown in.  A house that is well sealed from the elements will not rot.

Unless, of course, the ghosts are pee-ing on the stairs!


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

[User] ELI5 How can folding a paper 42 times reach the moon?

[Assistant]
Everytime you fold a paper it doubles in thickness.

Start with .1mm

Folds  thickness

1    .2

2   .4

3  . 8

4  1.6

5   3.2

So you can see in 5 folds our paper has grown to 32x the thickness. Imagine 37 more folds.

In fact given that we start with   0.1mm our thickness follows a nice relation that is t = (2^x ) /10   where x is the number of folds.

For example X = 2, t = 0.4mm

So using 42 we get t = (2^42 ) / 10 mm = 439804651110.4 mm or

 439804 km

The distance between the earth and moon is

384,400

So you can see on the 41st fold we would be at a thickness of ~200,000 km and with one more fold we would be past the moon.


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

[User] [Marvel] Between Iron Man and Doctor Doom, who is better at creating battle suits?

[Assistant] Iron Man. Doctor Doom is amazing at more things than anyone else, but everyone else is better at the one thing they're amazing at. Tony Stark is a better engineer, Reed Richards is a better scientist, Doctor Strange is a better sorcerer, T'Challa is a better king, Marchioly is a better man in an iron mask.


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

[User] [40k] Sorry if this has been asked before but exactly how powerful is the emperor of mankind, the chaos gods and the c'tan? What examples can you give of their power?

[Assistant] Currently the Emperor focuses the power of a thousand psykers into the astronomican, holds the webway under the golden throne closed, grants miracles across the Imperium (see saint sabbat), and is capable of stopping time to converse with people ( novel Inquisition war). Pre Heresy he was a god in everything but name, he could be in the presence of the Chaos Gods without going insane (implied by the implication that he got the tech for the primarch project out of a deal he reneged on with the gods), he glowed with Golden light and he could strip your soul from existence.


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

[User]
ELI5: why does a microwave have a popcorn button and the popcorn bag doesn't want me to use it?

Feuds? Elitism? Conspiracy? Bad programming?

[Assistant]
The popcorn brand has done extensive testing, popping hundreds of sample bags in a wide variety of types of microwaves.  Then they establish a general time setting that works for that specific type.

They have no idea how accurate your popcorn button is, but they don't want you to have shitty burnt popcorn and then blame them for it.  So they tell you to cook for ____ amount of time, and not to use the popcorn button because they have no clue how long your microwave's popcorn button might be configured for.


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

[User]
If all of the mass in the universe was to be inside of one black hole right now would the event horizon be larger, smaller or the same size as the universe is right now?

also if this was possible would this effect the rate at which the universe expands (especially if the event horizon of this black hole is larger than what the universe is right now)

[Assistant]
That black hole cannot form. In fact, that mass is already inside its own Schwarzschild radius: if you do the calculation that radius is about equal to the radius of the observable Universe, so you can tell already something doesn't add up.

An intuitive understanding for this is perhaps as such: the uniform distribution of matter that we see in the observable Universe continues on at least for a good bit beyond the cosmological horizon. All points of the Universe are mostly identical and none is special. This matter beyond the horizon pulls on you as much as does the matter inside. The overall effect is that this can make the Universe itself expand or contract (depending on the proportions of the various types of energy you can have in your Universe) but you cannot seal off one part of the Universe from the rest of it with an event horizon (which is what a black hole is) because that contradicts the fact that all points of the Universe are equal and are to be treated equally.


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

[User] ELI5: Why does taking a picture of something on a screen (laptops, cell phones, TV, etc.) cause bad pictures?

[Assistant] Because what you are seeing with your eyes isn't really what is there.  The screen is rapidly being written, top to bottom, over and over again. It is so fast that to you it looks like any other object, but your camera doesn't "see" things the way your eyes do.  Also, most cameras also do a scan when they take the image, also very fast, but often left to right instead of up to down.  This can lead to some weird artifacts.


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

[User] ELI5: How does a breathalyzer accurately measure BAC?

[Assistant] Simply, it doesn't. It is not particularly accurate at all - the roadside ones are only an indication. Back at the station the cops have a bigger, more accurate machine and could arrange for blood tests.


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

[User]
Why emulation over binary translation ?

There are a bunch of emulators, for Playstation 1 for example, but I've never heard of binary translators. Why is it easier to run a PS1 binary in software than translate the binary code ? I mean, if you can read an executable and call the respective functions that correspond to instructions of the emulated platform, why don't we encode the respective functions and translate the binary to function calls ? In addition, most operations could be translated directly to CPU instruction.

[Assistant]
because even if you did manage to do it, you would need to slow down the cpu or else the games would be sped up.

Also, it's not just about translation, but also about drivers and such as the games need to work with gpu and other, sometimes even special chips that aren't anywhere else (such as in PS2)


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

[User]
I'm 27, am I too old to start a new education that will likely last at least 5+ years?

Hello!

I've been trying to finish various engineering programmes in university because I've been told it's the best thing to do for money, but I've never really been interested nor motivated, so I've stagnated for years and gotten into debt. I've been working off and on in sales and I absolutely hate it.

I want an education, and I want something I'm genuinly interested in (primarily biology), so something like a bachelor in biomedicine (or maybe even biotech if I have to choose engineering) and then specialize with a masters. The problem is I feel like I'm getting old, already 27 with nothing to show for it, and if my education lasts 5 years, I'd be 32 by the time I'm finished; a licentiate or a PhD would make me even older.

I'm getting kinda depressed, and I'm not sure what to do. Am I getting too old to start working on a research oriented education?

In case it matters I'm Swedish.

Thanks.

[Assistant]
Youll be 32.... and then have like... what, at least 50 more years to live out life in whatever career that is! Thats a lot of time!!

Isnt that better than.. spending the next 54 years in one you dont like as much?


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

[User] [The Matrix] Once someone's body has been co-opted by an Agent for their program are they forever gone and replaced until they die? If so does an Agent have to kill their current host first in order to transfer themselves into another body in a different location?

[Assistant]
Nope.

When an Agent possesses a bluepill's body, the bluepill basically goes unconscious. When the Agent abandons the body, the bluepill will wake up, very likely confused at their sudden loss of consciousness and/or ending up in a different location or suffering serious injuries. If the Agent is killed whilst possessing a bluepill's body, the bluepill will be killed as well.

That poor homeless dude who Smith possesses to fight Neo? Dead. The pilot the Agent possesses on the rooftop? Dead. The two truck drivers the upgraded Agents possess in Reloaded? Dead. The cop who gets possessed by an upgraded Agent during the highway scene? Alive, probably suffering some bruises, and likely very fucking confused as to how he went from being in his cop car to being in the middle of the highway. Probably...uh, had an accident or something.


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

[User]
Eli5: What is the Simpsons paradox in statistics?

Can someone explain its significance and maybe a simple example as well?

[Assistant]
Say we want to see whether a medicine is effective at preventing heart attack in elderly populations. We see that among those taking the medicine, 5% suffer heart attacks compared to 3% of those who dont. Seems like the medicine is counterproductive right?

Say you look deeper in the data and find that among those with high risk factors, 20% of those without the medicine suffer heart attacks compared with 6% that do take the medicine. Meanwhile, among those without high risk factors, 2% who dont take the medicine suffer heart attacks, while 0.2% who take the medicine do. That means the medicine reduced the rate of heart attacks for both high risk and low risk people! However, an overwhelming majority of high risk people take the medicine, compared with maybe half or so of the low risk people. And since high risk people have such a higher baseline of risk, this means that those taking medicine are more likely to get heart attacks than those who dont even though the medicine itself makes them less likely.

Tldr: Simpsons paradox is when a correlation reverses itself once you control for another variable.


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

[User] [LOTR] Why does the Dwarven enclave of Moria have an Elvish password?

[Assistant] Iirc it was to allow entry to elves back in a time when they were more allied with each other. Hence the phrase speak friend and enter. The relationship between the two races had since soured though.


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

[User] ELI5: Why must we close our eyes in order to fall asleep?

[Assistant]
First off; *we don't*.

Secondly; closing our eyes prevents them from drying out during the night. There isn't a whole lot of blinking taking place during sleep, but there is certainly a lot of movement, which would dry out our eyes and potentially damage them.

Lastly; humans naturally sleep during the night due to the reduction in light, which makes it difficult and dangerous to hunt or gather food. Closing our eyes can help to simulate the darkness of night, so that we can sleep more easily and more comfortably.


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

[User]
What caused the big bang?

I have heard tons of conflicting theories on this and don't have enough mathematical skill to perform meaningful research on my own yet. So what was the prime mover or ignition, or what was the most probable cause?

Edit: Thanks everyone! Extremely clarifying.

[Assistant]
We don't know.

Our models of physics begin with the big bang - they describe the bang and its consequences but not anything prior to - or outside of that bang.

To the extent that such things are unobservable by us there is no constraint on what can be hypothesised.


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

[User] ELI5: what is a half life, and what is its significance in science?

[Assistant]
A half-life is the amount of time it takes 50% of any material to decay. Most often this term is used when talking about radioactive materials.

If Chemical X has a half life of 5 years, and you start with 1 gram, then:

* In 5 years, you'll have only 500 mg of usable Chemical X left

* In 10 years, you'll have 250 mg

* In 15 years, you'll have 125 mg

* In 20 years, you'll have 62.5 mg

* etc. You'll never theoretically reach 0 mg because you half the previous amount, not half the original amount.


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

[User]
ELI5: How does irradiation work for non-humans? (Trees, for example)

I watched Chernobyl by HBO and have some basic understanding of what radiation poisoning does to human cell structure. But what about plants? Why does the Red Forest still exist? Why there are grass and, probably, flowers all around the nuclear plant?

[Assistant]
So the way radiation works in basically every creature is that it's the cells that are currently being born that are the most heavily affected.

In animals new cells are constantly being born, and then those cells travel all throughout the body to go to work. So with radiation what happens is those cells end up all over the place and damaging all your systems, liver, lungs, everything and then once those systems are damaged there is very little your body can do to recover from that. If you liver fails you die. If your lungs fail you die.

For plants the exact same damage happens, in that their newly born cells get damaged. But plants have a few things working for them. First off, their cells don't travel all through the body in the same way, new cells get born right where they are needed. This means the damage stays localized. Secondly, unlike animals plant are a lot more redundant. Has a root completely died? Simple, don't use that root. Has a giant tumor grown around it's trunk? Reroute nutrients around it.  So even if they do get damaged they rarely die from it. It's more like getting a scar for a person, it's annoying but we will be fine given enough time.

Currently living cells get affected too, but it's usually not the biggest danger outside of *extreme* levels of radiation that kill you basically instantly. Even in this case plant cells have something called a cell wall around each and every cell, which helps protect against radiation a bit in the first place.


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

[User] ELI5: How did the united states end up with a two party system?

[Assistant]
Let's say that there are two political parties, A and B. Under the current US electoral system, whoever gets the most votes is elected.

So let's say third party C comes along, with beliefs that are slightly similar to party B. If C takes enough votes away from B, party A would often be elected, sometimes even without a majority of the votes (meaning, the number of B+C voters is greater than the number of A voters).

Some states and local areas have run-off elections, where if one candidate does not get a majority of votes, the top two vote-getters will have another election. In this example, if A and B get the most votes, the C voters would likely end up voting for the B candidate in a run-off election.

US elections don't have run-offs, so the C voter pool often becomes fearful of voting for C, because B seems to have more support, and A will likely win if C takes enough votes from B. So C voters vote for B out of fear that A will be elected, party B grows stronger, and party C never picks up steam. If run-off elections were allowed, party C voters wouldn't be as fearful and might eventually have a chance of gaining a foothold.

So why do state and local elections that hold run-offs usually have two parties? The influence of the national elections ends up trickling down to the local levels. However, you do tend to see more "independent" candidates at the lower levels of government.


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

[User]
[General Vampires] Could a vampire cop enter a house without permission if they had a search warrant?

Although come to think of it; a fake search warrant might do just as well.

[Assistant]
No.

While a warrant is a judge giving Officer Nosferatu permission to enter a dwelling, it isnt the judges home.  If it worked like that, the bloodsuckers would have discovered that little loophole ages ago.


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

[User]
[Question] A single function should never do several things

I read "A single function should never do several things" advice somewhere. Let's say we have the following code below, where lower\_and\_replace function cleary does multiple things, but when coding it is useful to make such shortcuts.

    def replace(string, a, b):
        return string.replace(a, b)

    def lower(string):
        return string.lower()

    def lower_and_replace(string, a, b):
        string = lower(string)
        string = replace(string, a, b)
        return string

I think the author of that advice meant that functions shouldn't change their behavior based on parameters, eg.:

    def lower_and_replace(string, a, b, should_lower=True):
        if should_lower:
            string = lower(string)
        string = replace(string, a, b)
        return string

lower and replace are just examples. They could be any arbitrary long functions.

Is my thinking correct? What about naming conventions?

[Assistant]
I do think that's a good example why a function should not do several things (though there are of course exceptions).

It's easier and shorter to do

`replace(lower(inputstring),a,b)`

Than it is to do

`lower_and_replace(inputstring,a,b)`


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

[User]
Cuba has a GDP per capita of 9,477 USD yet they are frequently described as a poor country, not upper middle income as their GDP per capita figures would indicate. Are the GDP figures wrong for some reason?

The world bank defines upper middle income countries as those with GNI per capita between $4,046 and $12,535. Thailand is almost always referred to as upper middle income and it's GDP per capita is  only 7,233. So why is it that Cuba is almost always referred to as a poor country? How are the GDP figures for Cuba computed? Is there manipulation of data? Is it harder to compute their actual GDP because of their economic system? Is there anything I'm missing that would indicate that it's actually a poor country and not an upper middle income one?

[Assistant]
>why is it that Cuba is almost always referred to as a poor country?

This is a media/politics question, not an economics question.

If you look at world bank categorizations(and other similar institutions),  Cuba is generally qualified as varying degrees of middle income (depending on the year).


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

[User]
What happens when my phone reaches 100% battery but is still charging?

Follow up question: what happens if I have a charger plugged into the wall and switched on but it isn't connected to anything?

[Assistant]
Technically, the thing you plug into the phone is not a charger. It is a 5 volt constant voltage (CV) power supply. OK, some can put out different voltages, but they are still CV supplies.

The charging is controlled by the phone. When the phone decides that the battery is fully charged, charging terminates, and the power supply continues to provide power for the phone.

When the power supply is plugged in to AC without a phone, it still puts out a constant 5 volts.


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

[User]
CMV: Tobacco use should be made Illegal.

Smoking is really bad for you. Everyone knows that, and its why there are manky pictures of gums and lungs on fag packets and you cant have adverts with camels in. But, if its so objectively bad for you why hasnt the government, you know, just banned it?

Tobacco smoking has no health benefits. None. It can be argued that nicotine, one of the thousands of compounds in tobacco smoke, can have positive effects on some cognitive functions and may even confer some neuroprotection, but getting nicotine from tobacco products may be likened to sucking on a tail pipe to get oxygen  its there but its not going to do you any good. Yet tobacco is legally sold in virtually every country in the world and, after decades of understanding its harm, it remains not only legal but highly accessible and profitable to everyone but the consumer.

One of the main arguments for the continuance of tobacco sales is that the government should not dictate what vices the public engages in. This is a valid point. Alcohol and gambling are restricted but not prohibited; fast food is unrestricted; and, although government intervention is on the rise, few are protesting access to these products. These other sins, however, have at least some benefit. We need gasoline, we need to eat even if we occasionally do so at fast food restaurants, alcohol in moderation has benefits and gambling in moderation is entertaining for some. However, there is no moderation in tobacco. There is no level at which tobacco smoke is safe for the consumer or the people around them or even those who are exposed in a tertiary environment

There are benefits from tobacco taxation including fewer smokers, higher government revenues and a healthier society and we should applaud the use of the excise tax lever that the government can use discriminately. However, the direct and indirect cost of lung cancer, asthma and chronic obstructive pulmonary disease is huge, of which smoking is considered to be the number one cause. Thats not a good trade-off, even if you only consider it economically.

So why do we, as a society, continue to approve of tobacco sales?

[Assistant]
America already tried Prohibition.

Alcohol isn't good. It causes both health and social problems. We'd largely be better off without it.

When we tried to ban it, what we got was... massively powerful criminal gangs, corruption, and a diminished respect for the law and government in general.

That's the issue here. You can't just flip a switch that says "tobacco is gone now." You have to deal with millions of angry addicts who will do anything they can to nullify that law.


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

[User]
[General] How does time travel work if souls exist?

Let's say my wife dies and her soul plops into heaven. I develop a time travel machine, go back, and save her. Did I just save some carbon copy of her and her soul remains in heaven? Or did I pluck her eternal soul from heaven and place it back where it was before the incident?

[Assistant]
It depends on which time travel system you're using. If it's single timeline, then either you saved her, in which case she never went to heaven, or you didn't, in which case she always did. If it's multiple timelines then souls split each time the universe branches, so there's a copy of the earlier version of her in heaven and another copy in this universe. Or maybe there were infinite copies of the universe to begin with, and in some her soul went to heaven and in others it did not.

Though souls often don't follow the rules of time, so maybe it's different. Perhaps after she dies the first time she reincarnates in the next universe but loses her memories. Perhaps her soul simply exists in all those times and places and also in heaven and the concept of time doesn't matter to a soul.


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

[User]
The "highest degree received" question

So, I've noticed in applying to academic positions (assistant professor, etc.) that there is generally a question with a drop-down menu asking for "highest degree received", which lists BA, MA, PhD, etc. as part of the application process. As an ABD student, I don't yet have a PhD, so it seems that I should choose MA. However, I know that a lot of HR software automatically filters those candidates that are don't meet the requirements of the position. Given that TT positions all require a PhD, but I don't have one as of yet (but will), is it a mistake to choose MA as highest degree? Does anyone know how these things work? Any answers are much appreciated.

[Assistant] Put PhD, on the grounds that presumably you're applying for jobs you'll take up after conferral. Be very clear in your CV and follow ups and interviews what the actual circumstance is, but if you're applying for jobs to take up after you've gained the PhD, then you will have the PhD for the purposes of the job.


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

[User] [Austin Powers] Why does Dr. Evil want so much money when he clearly has enough money for all the resources he needs? (Submarine, moon base, volcano island, tons of staff, etc)

[Assistant]
Money is a red herring.  He just wants to inflict his well educated evil intentions upon the world - make nations grovel at his feet.

Shave some nut sacks.

You know, maybe even found his own evil academy?    Evil ballet.  Evil choir.  Evil band.  Not to mention offering direct Microsoft scholarships.


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

[User] ELI5: How does the sound of your phone transfer through headphones?

[Assistant] The headphones contain speakers like the phone does, a flexible diaphragm which is caused to vibrate with an electromagnet to make the air vibrate. The wire connecting them to the phone conveys the electricity to actuate the electromagnet.


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

[User]
[Star Trek DS9] How long would it take the Enterprise D to travel to the Gamma Quadrant without using the wormhole?

If the Enterprise D were to travel to the Gamma Quadrant and go to the exit of the DS9 wormhole, how long would it take (without using the wormhole itself to get there!)?

[Assistant] The Enterprise D can maintain a speed of about Warp 9.0 for sustained periods of time.  The Wormhole ends are about 70,000 light years apart.  Warp 9 covers a light year in about 4.63 hours.  So it would take 37 years  if they didn't have to stop.


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

[User] If a spacecraft somehow accelerates from a space station to 0.995c (relative to the space station), and the spacecraft shoots an electron beam (not light) going 0.990c at the space station, then would this electron beam ever reach the space station?

[Assistant]
No, the electron beam will never arrive. Relative velocities still obey the sort of common sense you think they will. If a guy throws a ball 5 mph backwards from a car going 60 mph, then the ball is still going 55 mph forward with respect to the ground.

Same principle here, but a little more special relativity. Since the electron beam is moving 0.990 c in the spaceship frame, which is in turn moving 0.995 c the space station frame, we need to Lorentz transform the velocity by the Einstein velocity addition formula:

    (0.995 - 0.990) / (1 - 0.995*0.990) = 0.334

So the electron beam is still moving *away* from the space station at a third of the speed of light.


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

[User] [MCU] It's been established in the MCU that the 9 realms are just different planets. But then how did the convergence happen?

[Assistant]
The Nine Realms are connected by naturally occurring cosmic phenomena, structures along which wormholes can naturally form. The Asgardians exploit these interstellar tendrils with the Bifrost, which allows them to force open wormholes between these cosmic branches, and travel from world to world.

During the Convergence, all these wormholes in-potentia started opening up. Ultimately just a weird natural cycle that we happen to be in the middle of.


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

[User]
[Warhammer 40k] Can you have void shields open at the same time as gellar fields? (and other questions about gellar shields.)

Or are the two shields mutually exclusive?

Can you have void shields up when in the warp? Or is that impossible/meaningless since they rely on the warp to function?

Is ship to ship combat using regular weapons possible when travelling in the warp? Or does that require you to move so close to a enemy vessel that your gellar bubbles merge?

And finally, how well, if at all, does gellar fields protect you against weapon fire?

[Assistant]
All the gellar field does is close in "reality" around your ship keeping the warp out. This means daemons cant make your ensign explode in a ball of puss and flies.

It has no effect on ordinance, you can and should run both shields at the same time.


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

[User] ELI5: Why do volume sliders in applications never seem to provide a linear increase or decrease in volume?

[Assistant]
Human perception of volume changes is not linear, it's actually logrithmic. For example, the perceived change of about "twice as loud" is about 20 times higher than the original (it's around a change of 10 dB).

If you put a linear slider, meaning if you move it up and down it changes the volume linearly, it doesn't sound linear because we don't perceive it like that. You need a logarithmic slider to get a perceived linear change. Good developers use a logarithmic slider, bad ones don't.


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

[User] ELI5: Why am I utterly terrified of death?

[Assistant]
I think the best explanation is the evolutionary one. Those people (and other animals) who weren't absolutely terrified of death didn't put out as much effort to avoid it and might have even welcomed it.

It's better from a survival perspective to be scared and wrong (you're just embarrassed) than relaxed and wrong (you get eaten by a tiger). So the neurotic ones tended to survive longer.

(But of course, it's not better on a daily basis to feel that way.)


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

[User] ELI5: Why don't flies seriously fuck themselves up when they fly head-first into a wall or window?

[Assistant]
Mainly because of their size. The weight of an object depends on its volume, and its strength depends on its footprint or cross-section.

If you halve the size of a body, it will have 25% of the original footprint or cross-section, but just 12.5% of the original weight. Halve it again and it'll have 6.25% of the original footprint, but just 1.5625% of the orignal weight.

Because there's so much stregth and so little weight, you would need a very high speed impact to kill a small animal like an insect, but an elephant would break its bones if it fell from even a moderate height. Basically, the smaller an object, the stronger it is.


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

[User]
On Killing Vampires...

If I shoot a vampire with an arrow with a metal point but a wooden shaft would the vampire die? Does the Vampire need to be pierced with a wooden point to kill him or does he/she only need wood to touch the heart to die?

[Assistant]
There's more breeds of vampire than there are dogs and they all take different ways to kill. Some of them it's just anything sharp in the heart, some of them it's anything wooden in the chest, some of them it needs to be a stake of hawthorn hamered all the way through the heart and into the earth below, some of them just take a bullet to the head.

Trying to figure out if the one you just shot didn't die because you didn't use the right kind of arrow, or you missed the heart or it just isn't one of the ones you can kill like that is difficult, especially when you are facing an irate bloodsucker.

If you are planning to shoot a vampire with an arrow, use a good sharp steel tip, because wood has a hard time punching through flesh and plenty of them are smart enough to wear armour as well. Or come up with a better plan; one that uses explosives and incendiaries.


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

[User]
ELI5: Why do businesses in lower income areas use brighter colored signs with more information than businesses in higher income areas?

This also seems to be present in packaging for products, the lower end the product, the more that is written on the package and the brighter the colors.

[Assistant] I don't know about product packaging, but store signage is regulated by the local government.  It's very common in affluent communities to have very strict rules, and "drab coloring" using dark blues, greens, and browns is a requirement in the wealthy planned community near me.


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

[User] ELI5: Why are we required to finish a course of antibiotics?

[Assistant]
Let's say your body is like the lawn in front of your house.

You've got grass, and some bushes, maybe a tree or two. All of these are good things you want to keep around. But then some ugly weeds start growing in your yard and your dad wants to get rid of them.

He goes to the store and buys some weed killer and sprays it on the weeds for a day or two until the lawn looks better. But your dad didn't follow the directions, and now not only does he have half a bottle of weed killer left, some of the weeds didn't really die - it just seems like they did.

The weeds that survived, grow stronger, and move to your neighbor's yards. It takes stronger weed killer to affect them, sometimes strong enough to hurt the grass and bushes that you want to grow there.

If your dad had followed the directions, and used the weed killer properly, his lawn would be healthy, and he wouldn't be ruining his neighbor's lawns too.

[Source: currently studying clinical microbiology]


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

[User]
[Ghostbusters] Why did Gozer ask the Ghostbusters if they were gods?

To what end would this question have served her?

[Assistant]
Ray had just ordered her to leave.  She was asking to determine whether she was trespassing in the realm of another deity.  If she found out she was, it would affect her next choice of action.

She may have challenged the new god for dominion over this world, fled to avoid a fight, or proposed some kind of alliance - we can't really know.


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

[User]
ELI5: How are big scale things like rivers and mountains measured?

e.g.

"Mt. Everest is 8848 metres tall from sea level" or "Amazon River is 6575 km long." or even stuff like "the area of the US is 9834000 sq.km."

How do they collect the stats of how tall a mountain is or how long a river is, or how much area does such a large area have. When they are all so large, they definitely won't use a ruler to do it, right? (Or am I wrong and they actually do lol)

[Assistant]
Triangulation.

If you have two points of a known height and distance between them, you can place an observer at one point, have them measure the angle and distance from the second point to the third point, and mathematically derive the height and distance of that third point.

So let's say you take a particular measurement, like the top of the Washington Monument. You do the annoying work of measuring its height exactly (with a very long measuring tape if you have to!). Then you do the same with another point that's visible from the first - like the top of the Capitol Building's dome. Now if someone is standing on top of the Capitol dome, they can measure the height and distance of every visible building in Washington, knowing the measurer's own position and that of the tip of the monument.

Then they just keep doing that, moving on to the next tall visible point within line-of-sight. Then when they get somewhere flat, they put a long stick at a particular spot in the distance, and keep moving that way. (When you see construction crews today with looking-glasses on a tripod, and another dude holding a long high-viz yellow stick somewhere in the distance, that's what they are doing - measuring the height and distance of the ground very exactly.)

And yeah, doing that enough to cover the entire country, or up to the points of the Everest and so on, is a very tedious job. It took super-organized governments to do it.

(These days of course we can check it with GPS, too. And for something like Mount Everest, you can use a very sensitive barometer to measure the air pressure at the top and at sea level to calculate the height. Etc.)