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ELI5: What exactly is a Zero Hour contract, and why is it causing such a split in the working community? | So many people seem to think they're either great, or the devil's work.... What exactly is all the fuss? | 22 | A zero-hour contract is one where the minimum hours you can be expected to work in a month is zero, but you still have to be available for work whenever the company needs you. You will not be compensated for being on call, only for the hours you have actually worked.
If you have an amicable relationship with the company then its can be a very flexible way of working. A lot of times though people are forced into them as they are the only job available, and the company can threaten to withhold further hours if you complain about safety or unpaid overtime. | 23 |
ELI5: Why aren’t there any medicines against the flu? And in general, against many viruses? | 19 | Viruses aren't alive so they're impossible to kill.
Bacteria are alive, they have to take in nutrients and have many chemical processes that go on, and antibiotics are chemicals that actively disrupt those chemical processes. A virus is inert, there's nothing to turn off and they don't "eat" so you can't make them take in a poison.
Viruses inject their DNA into a host cell and then uses your own cell's mechanisms to build more viruses. This is hard to interrupt without turning off the normal operations of your cells which you know, keeps you alive.
Many viruses can be protected against via vaccines, which "teach" your immune system to recognize the virus and destroy it. Cold and flu viruses are highly adaptable and rapidly mutate to avoid this, so getting as flu vaccine this year only protects you from a small number of flu strains and not from any new mutations of flu.
Tamiflu is a drug used to stop flu virus by interrupting the ability for new viruses to exit a host cell, slowing down the spread of the virus inside your body. It's no good to you if you take it after the flu has already spread, and doesn't work against other common respiratory viral diseases. | 17 |
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If two or more countries owe each other money, can they cancel out their mutual debts? | Hi everyone,
My question about economics is inspired by this post:
http://www.reddit.com/r/todayilearned/comments/3bjy51/til_the_us_owes_less_to_other_countries_than_its/
It seems that the governments of most nations owe a lot of money to the governments of other nations. If we lived in a simplified world with just two governments, then they could forgive each other's debts simply by canceling it out.
Similarly, with three governments A, B, and C where A owes B, B owes C and C owes A the same amount of money, the debts could be canceled out by three countries "paying" in cyclic order A -> B, B -> C, C -> A. However, since each country receives and pays the same amount, nobody has to pay anything.
In principle this could be applied to the world economy, only there are many more governments and the amounts are different. I think it would probably be an optimization problem in graph theory.
Does this kind of debt cancellation occur in real life, and if not, why not? Is it because each piece of the debt comes with a different interest rate?
Edit: My question also applies to heavily leveraged financial institutions.
| 21 | Hypothetically yes but most countries would have no desire to do so, they hold debt of other sovereigns for good reason (EG playing a forex game, ensuring a flow of foreign currency etc).
They would not cancel the debt but rather hold it until maturity, when the coupon payment is made its made to itself and zeros. This is (indirectly) what occurs currently with the fed, they hold Treasuries and when these mature TD pay the fed the coupon value and the fed remit that back to TD (last year ~$100b). Between different governments the complication is calculating an exchange value, the value of government debt is modified by its risk so it wouldn't be straight coupon for coupon.
| 12 |
ELI5: Why does the severe weather alert system that broadcasts over your television sound like I'm logging on to the internet in the 90's? | We are having severe weather here and they just did a test over the tele and it got me wondering. | 261 | It's actually quite intentional.
The Emergency Alert System is designed to be broadcast in case of any emergency, whether it's a weather alert or a Presidential Alert. The system doesn't differentiate where the signal is sent, and is broadcast nationally for each alert, but you don't see the ones that don't apply to you because of those tones at the beginning of the broadcast.
The first time the modem noise is played, the EAS is broadcasting information about the affected area, the type of alert, and the originator to the EAS device located at the station. This code is then repeated two additional times in order to ensure that the data was correctly interpreted on the receiving end. The receiver at the broadcast station reads this data, determines automatically if the alert is valid for the broadcast area, and cuts into whatever is playing in order to relay the information.
This is the same principal as the handshake your modem used to connect to the internet, but with different data since certain things are assumed (Baud rate, transmission format, frequency, etc.)
The three tones at the end of the EAS broadcast are the "End of Message" tones.
TL;dr: It's because the alerts are sent by a system that's pretty close to a modem.
(edit: Moved a few letters around for clarity's sake.) | 172 |
I guess I don't understand evolution. It is 100% purely random mutation? | So, I feel like a fucking idiot, here, because this has always confused me. I thought I understood the theory of evolution, but years ago I had my understanding of the concept turned upside down when someone explained to me that evolution does *not* mean that a species evolved in order to adapt. Rather, species evolve constantly due to mutation for no specific reason, and the ones that *just so happen to have evolutionary traits that help them adapt* are the ones that survive.
Maybe it's because I grew up thinking that evolution had a reactionary part to it, but it's just hard for me to grasp the idea that we seem to only have evidence of species with evolutionary traits that seemed to serve a purpose in the environment. I mean, if evolution is truly random, is there a reason we don't have evidence of species with seemingly random traits, such as a mouth on ones hands?
Maybe people just find a way to explain how the mutations of different species are beneficial, which gives the illusion that there is causation there, but I just feel like there's this veil over my ability to understand this that I'd love some clarity for. | 90 | Evolution is not goal-oriented in the sense you originally thought. It has no agency. Mutations are definitely random. But the process of evolution that acts on those mutations is not really.
Natural selection (the mechanism of evolution) is often described as survival of the fittest. Another way to think of it (that is perhaps a little more accurate) is elimination of the unfit. (Fitness in this sense just means the capacity of an organism to reproduce and pass on its genes to subsequent generations.)
Random mutation generates genetic diversity. Some traits that result from these mutations are adaptive ("useful"). This will allow individuals with those traits to survive to reproduce at higher rates than organisms without those traits. Some random mutations generate maladaptive ("bad") traits that do actually are detrimental to an individual's survival. Organisms with maladaptive traits therefore don't survive long enough to reproduce. Or if they do, it isnt at the same rate as organisms with more adaptive traits.
So what traits appear is random. But what traits persist in a population (what is or is not adaptive) is not really random. It is entirely dependent on the environment. For your example, a mouth on the hands of a colobus monkey would likely be maladaptive. Yeah, it seems super cool, but the colobus monkey uses its hands to manipulate the environment around it and to locomote. A mouth-hand would get in the way, be prone to infection or irritation, etc. So any colobus that randomly developed that trait due to mutation wouldn't survive very long and therefore wouldn't reproduce, deleting the maladaptive trait from the gene pool. This is natural selection at work.
Tl;dr: mutations are random, but natural selection (the mechanism of evolution) is not. | 119 |
Eli5: Why does jumping off two legs result in roughly the same height as when using one leg? It would seem 2x the upward force should result in a much higher jump. | 76 | Most people can jump higher off of two legs. All people can jump higher off two legs if they are standing still. The reason “leaping” is a thing and some people can get really high off of one leg is because they are moving forward. When a basketball player makes a running leap, he converts some of his forward motion into upward motion. He sort of uses his forward leg as a “ramp. The forward foot is planted on the ground and the legs is kept sort of stiff. For the body to keep moving forward the leg forces it to also go up. It’s very awkward to do this with two legs. | 126 |
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I don't think these 'black boxes' that are in many new cars, and that will be required by the end of 2014 are a very big privacy issue. CMV. | I've been seeing quite a bit about these event recorders lately. They're currently present in 96% of all new cars sold today, and will be required in all new cars by law by the end of the year (I can't recall the exact date off the top of my head.)
From what I understand, these devices have a buffer that usually holds between one and several minutes of various pieces of information about the car's state with timestamps, such as speed, accelerator/brake depression, steering wheel position, seatbelt use, headlight on/off state, and quite likely many other bits of information I'm forgetting. In the event of an accident, it will trigger the device to flush its buffer to permanent memory so that it can be analyzed in the future.
I've seen quite a negative reaction to these things whenever a link to a news story relating to them is posted. I'm a bit confused about what the big deal is though. It seems the very worst abuse of an event recorder will only be able to garner an advesary the last several minutes of your driving habits. Plus if someone was inside of your car to read the data off of it, they could easily do something far more invasive of your privacy anyways, like installing a GPS tracker.
So... First of all, is my interpretation of how this device works accurate? Second, why should I consider it a threat to my privacy? | 18 | What about a future software update for your car that increases this recording time from 5 minutes to 30? And the next one which uploads this data to the manufacturer's servers for permanent storage. Oh and the 300 page agreement you signed during purchase enables them to use this information as they like to "improve your driving experience".
These improvements include selling your driving patterns to companies that can analyse them and target advertisements based on your behavior. Banks and other lenders can know where you have been driving and adjust your rates accordingly. Soon the police wants this data too, to track people driving in the *wrong* parts of town. It's for your own safety of course, they're just fighting terrorists. Not to mention the inevitable data breaches that will occur, jeopardizing your very safety.
I don't know too much about these devices, and sure they sound great in theory, but only for as long as they just do what they were initially intended for. So to me, and many others, all such intrusions to privacy are to be treated with caution rather than willing acceptance. | 16 |
[The Muppets] I’m a human associate of the Muppets. But do I live in the real world, where Muppets are skilled thespians, or do I live in the fourth wall breaking fictional world that is the Muppets films about versions of themselves. | 24 | Are you asking if you're a very manly muppet, or if you're a muppet of a man?
But to answer the question, if you're interacting with muppets, you live in the muppet world, not the meta-world that watches muppet movies but does not include actual muppets. | 18 |
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How would an atom bomb effect us if blown up in the sky? | As stated, how would an atom bomb effect us if blown up in the sky?
I understand the radiation would get to us, but what about the shear force from the bomb itself?
EDIT: Meaning in the sky at a high altitude, I did not realize that nuclear bombs were detonated around 500-1000 meters above ground level.
EDIT2: I appreciate all the responses to this question! You guys have helped me out so much. Thank you! | 17 | Atom bombs are _supposed_ to blow up "in the sky" to maximize the explosive power. E.g. "Little Boy" (Hiroshima) detonated at an altitude of about 600 meters/2000 feet.
It's true of dropped bombs in general, since WWII they've mostly detonated using a proximity fuze rather than a contact (impact) fuze.
| 36 |
[Marvel] What would happen if captain America, Black Widow, and Hawkeye were absent during the battle of New York? | How would the battle have gone differently if it was all down to Stark, Banner, and Thor? | 26 | There would probably be a few more civilian and police casualties due to The Cap not interacting with the people. But really there would be about 200 more aliens for the rest to dispatch and Bruce Banner would probably just appeared as The Hulk instead of just casually riding in on a motor bike. | 28 |
eli5: why is the ocean salty but most lakes and rivers are not? | 18 | Water moves in a cycle. It evaporates into vapour, which condenses into clouds which the rains onto land. Salt is left behind when water evaporates.
This rain travels over or through the land, and where lots of water collects together, that flow forms streams and rivers, which can flow into lakes. Further water can then flow out of the lake and and ends up in the sea.
Rivers and lakes are the stage between clouds and the ocean, so it's never had the chance to get salty.
There is also "brackish" water, which is the mix of fresh and salty water you find in river mouths and estuaries. | 28 |
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ELI5: Why do lawyers specify that they are “attorneys at law?” Are there some attorneys that are not “at law?” | 927 | Yes. An attorney is just someone that represents you and make decisions on your behalf. This could be in a legal, business or medical context. You can grant anyone "power of attorney" and make them responsible for making decisions that are legally binding on your behalf. This frequently happens when people are too old, too young, too uninformed or too feeble to act for themselves.
An attorney at law is someone who makes a living by specialising in being appointed to act in just a legal context. | 1,830 |
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Can someone give me a Halo world overview? | I know the basic story in Combat Evolved, but i have no idea what has happened before it or after. | 15 | Long story short: It's the year 2550 or something and human kind has spread out over the stars, colonizing worlds and fighting some small wars against itself. The Human Government is the UNSC (United Nations Space Command) and it's HQ'ed on Earth. The UNSC's largest military base (aside from Earth) is a planet named Reach where they produce ships, train soldiers, etc.
Anyways, at some point, an enemy known as the Covenent make contact with a far off human colony named Harvest (which colloqially was used to grow food for other worlds). The Covenent invaded Harvest and burned the planet down with powerful weapons. The USNC sent several ships to investigate, and all but one were destroyed.
Eventually, the UNSC sent a HUUUUUGE fleet (led by Adm. Cole) to attack the enemy, and won! At the cost of 3 Human ships to 1 Covenent one. Its was a terrible victory that would set the tone of the Human-Covenent War for like the next what? 50 years? Anyways, the Covenent are deemed to be such a threat that the locations of places like Earth and Reach are deemed top secret, and human forces are no longer allowed to retreat to them out of fear that the enemy will find them. This is known as the Cole Protocol.
Anyways, over 50 years, humanity is slowly getting its butt kicked. While they win some battles, they ultimately are pushed back. Eventually, the Covenent find Reach and launch a massive assault on the planet. Hundreds of ships are destroyed, the planet is bombarded, and the human military forces are thrown into disarray. After Reach falls, all that is really left to effectively resist the enemy is Earth.
This is where Halo:CE starts. The Pillar of Autumn just left Reach as it collapsed, picking up the Master Chief on the way out. The enemy chasing them, they couldn't goto Earth or another human planet, so they made a blind jump away from the planet and ended up at Halo.
Unfortunately, the Covenent beat them there, the Pillar of Autumn was shot down, and the fight for the Halo begins.
After the events of Halo, the Master Chief and survivors of the events in the game made their way to Earth. They did so by hijacking a Covenent Carrier, a huge ship. They fought their way back to Reach (to find a human ship which might have coordinates to Earth or something), picked up a bunch of other Spartan survivors they managed to find, and used the advanced weapons of their new ship to their advantage. They eventually figured out how to take Covenent weapons on the ship and advance them to the point where they would kick the crap out of the Covenent ships. Anyways, they eventually stumble upon the Covenent invasion fleet poised to attack Earth, the Spartans infiltrate the central command ship (a huge space station) and sacrifice their Covenent Carrier to blow the whole fleet and thing up.
The Master Chief made it out (lost everyone else on the huge space station) and took a human ship to Earth. A few weeks later, he's on a space station getting an award when... badum dum dum: the Covenent attack!
Then Halo 2-3 happens. | 24 |
Given that asteroids from Mars are found of Earth, would asteroids from Earth be found on Mars? | And, if we find life on Mars, how would we show it wasn't just seeded there from Earth from one of these asteroids?
I know that we have found chunks of Mars on Earth in the form of some very rare asteroids. The thought being that pieces of Mars could be thrown into space during large asteroid collisions. Could this happen in reverse?...maybe with some large impact like the Yucatán impact of 65-million years ago? | 19 | Sure, but it's much much more unlikely. Earth's gravity is a lot stronger than mars, 9.8 m/s² compared to 3.7m/s², so that already makes it harder for chunks of earth to leave and go flying around aimlessly. Earth also has a much thicker atmosphere, so most meteors won't be enough to leave a crater on earth, nevermind send material flying at terminal velocity, so only really catastrophical impacts could have a chance at shooting anything into mars. Mars' smaller gravity also makes it harder for it to "catch" a meteor that is sent in its general direction, it'd be likelier to just whizz by. But nothing stops it from happening. | 21 |
[Marvel] How is Iceman considered an omega-level mutant? | I have read one of the biggest things he can do is produce a mass ice over of the Earth killing everything, but that doesn't seem too sound to me.
Another I though of was just moisture absorption and dry everything out maybe.. | 37 | Remember in elementary school how we learned that when liquid water molecules are slowed down they turned into solid ice (and turns into vapor when sped up)? That. **Iceman doesn't JUST create ice--he's controlling energy at the atomic level.**
WHOA.
Now how's that for Omega-level? | 25 |
CMV: I think churches should pay taxes. | > "And Jesus said unto them, Render to Caesar the things that are Caesar's..."- Mark 12:17
I was ordained as a minister in the [Universal Life Church](http://www.themonastery.org/) maybe 15 years ago. I registered online and it took 5 minutes. With a little creativity and some paperwork, I could apply for [tax exemption](http://www.irs.gov/Charities-&-Non-Profits/Churches-&-Religious-Organizations), perhaps by starting a commune?
My commune would use the same public resources as everyone else. As a private citizen, away from my organization, I could send my children to public schools, claim welfare benefits, and enjoy the relative protections and upkeep of the state. Pending how charismatic that I might be, I could have a relatively large compound with surface parking, attracting thousands of visitors, perhaps straining the roads and sewers of the small county that I reside in.
It might not be easy to incorporate as a church, and I may be less than sincere, but it is possible. My special authority on the universe will be difficult to challenge and I might tap into thousands of years of western religious traditions to cement my point.
Ultimately, the value that I provide as a church is only moderately questionable as the pretense is difficult to rule upon without infringing on my religion.
If I paid taxes on my church's earnings, then I would contribute to the quality of services provided by my state. I would be free to lobby legislative bodies and more fully engage my government as a paying participant. I could still incorporate as a nonprofit on the clearly defined activities that I participate in which do qualify with measurable purpose, but the effort that I spend reaping souls would be my own enterprise.
Is there reason why church's shouldn't be treated as any other organization? I heard this view years ago, "Churches should pay taxes", and it has always stuck with me. I can't seem to view them as anything more than a personal endeavor that I subsidize as a citizen tax payer.
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**Edit:** Users cold08 & miyakohouou have changed my mind. Without considering the power dynamic, I would feel that the tax exemption of religious organizations is antiquated gratis to indulge something rather unnecessary, but in reality it's a leash that keeps those influences guarded. A taxable entity can participate and fully lobby for their causes with all coercion, influence, and wealth afforded to them, factors of which that are mitigated by the controls of an exempt status. Further a profitable tax entity will find policy protections from dependent governments. The potential for abuse is concerning. I no longer think churches should be taxed. The analogy would be grabbing a wolf by the ears.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | 133 | I think the best argument that I've seen for not taxing churches is that if churches do not generate revenue directly for a government then that government does not have a strong incentive to encourage churches, and therefore it helps keep the relationship between church and state more neutral.
If churches were a significant tax source for a local government that government might then be more inclined to try to indirectly encourage more churches, or encourage it's citizens to be more religious in order to increase the revenue of the church and therefore the state revenue. If churches were paying taxes a state might feel pressure to pass laws that agreed with a church's moral stance in order to keep the church, and tax revenue, in the states tax collecting area. | 54 |
How do we know that things like murder and rape are obviously wrong? | 110 | u/Voltairinede gave an account of how to *explain* the wrongness of murder and rape. But the question is how we know these acts are wrong, and the answer to that seems to me -- along with a bunch of philosophers -- "It's common sense".
In fact, many counterexamples to ethical theories like utilitarianism or even Kantian deontology take the following form: *find a case where obviously we ought to do P and the theory in question recommends not-P*.
E.g.: (1) we can construct situations where rape is required to maximise utility, and therefore utilitarianism must be wrong or (2) we should straightforwardly lie to protect human life, therefore Kantian morality is wrong. | 62 |
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[Starwars] Are the storm trooper's helmet the reason why they lose to the ewoks? | 25 | No that wasnt the reason, The reason they lost is because their armor stood out against the foliage, Where the ewoks could blend in, the ewoks outnumbered the imperials at least 5 to one, and the inperials were stationed to repel a rebel ground assault not an uprising of the native populace
Keep in mind the Ewoks, while adorable, are also terrifyingly efficient, Subduing the rebel landing party within a few hours of them tresspassing into ewok territory | 59 |
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Why don't other viruses nearly eradicated by vaccines not evolve to evade immunity like Covid does? | Covid-19 has seen lots of variants that evade the immune response from prior variants, either acquired from the virus or from vaccines made based on their spike protein characteristics.
Measles is incredibly infectious but historically we were able to nearly eliminate it in the Western world. Why did it not evolve to evade vaccine induced immunity like Covid does? | 20 | Flu is able to swap large sections of its genome, since it is segmented. It also travels through various different species (birds, pigs, human etc), so flu can and does mutate quite a bit. More than CoVid, by far. CoVid and measles mutate at the same rate on a molecular level, but the measles spike protein is very highly constrained, and any number of mutations that would allow it to escape neutralizing antibodies would inactivate its ability to bind and enter the cell. Unfortunately we are learning that CoVid is not nearly as constrained, and is able to remain effective at binding even in light of multiple mutations. | 15 |
[LotR] Is elves being twisted into orcs a reason for the Elvish kingdoms decline? | 25 | No. For one thing, it's uncertain what the origin of the orcs actually is; the idea of orcs being corrupted elves is only one of several theories. Beyond this, even if orcs are descended wholly or partly from elves, they reproduce biologically, in the same way that any of the other races do. The origin of orcs lies far back in the past of the Elder Days, long before the elvish kingdoms reached their height and began to decline. The orcs were well-established before the time of the great elvish kingdoms of the First Age, and were spreading and multiplying on their own without requiring any additional tinkering on Morgoth's or Sauron's part. The decline of the elves is more closely tied to the nature of Middle-earth, or of "Arda Marred", than to specific actions on the part of the Dark Lords. | 31 |
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ELI5: Why people recommend breathing in a bag when nervous. | 20 | The bag traps some of the carbon dioxide that you're exhaling. Carbon dioxide levels in the bloodstream tend to lower when you feel stressed out or anxious. Breathing in some of that recycled co2 will raise the level in your blood, making you feel better and more balanced. | 14 |
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[MCU] So what's the deal with the fake infinity gauntlet/timeline of invasion of Nidavellir? | So in the first Thor (2011) we see the Infinity Gauntlet in Odins treasure room. At the end of Age of Ultron (2015) Thanos grabs his gauntlet and says he'll do it himself. Then in Thor Ragnarok Hela,imprisoned for a millennia, tells us its a fake. In Avengers: Infinity war we learn Eitri forged Thanos's Gauntlet after they were invaded and the dwarves have been all but extinct since.
But Hela saying it's fake implies that there is a GENUINE one. And has been for at least a millennia for Hela to know it was fake like that.
So did Nidavellir get invaded by Thanos a thousand years ago and nobody noticed? But Odin somehow then learned about the plans and designs for a sweet gauntlet and had a replica ordered up to commemorate the slaughter of an entire race he was sworn to protect? Or.....what? | 86 | No. The one in the treasure vault is a fake - we just don't know how Hela knows it - likely she knows that Odin knows. There already is a mold in Nidavellir, but we don't know if that's related to the fake. That doesn't imply she knows there is a real one. That could have been commissioned by anyone.
The one that Thanos grabs from his vault is the one that he had made from invading Nidavellir. It takes place a few months before Ragnorock because during that Time Thor has been unsuccessfully finding Infinity stones. That's when the realms fell under further disarray.
The scenes are not in order chronologically. Its somewhat confusing since the gauntlet was not meant to be in Odin's vault - Thor's original director had no idea that they were going to use it later down the line with Infinity stones. Thus, Hela knows its a fake. We don't know how she knows, but she already sees Odin as being a fake anyhow. | 72 |
ELI5: Arcade "Kill screens"? | 17 | The simplest way to describe it is to say that a killscreen comes from being asked to perform a task that is impossible from a strictly literal perspective.
Lets say you have a simple task--moving sand from pile A into pile B using only a spoon. You have a time limit of five minutes to do this, and you are only able to move your arms at a fixed speed. Each time you finish moving pile A to pile B, pile A is replaced with an even bigger pile of sand and you have to perform the task again. If you keep repeating this pattern, eventually the pile of sand is too big to move in five minutes.
The most common example of this is Donkey Kong, where the killscreen represents a level where you are forced to get to the end in an amount of time that is strictly impossible to complete not only practically, but in theory. | 10 |
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ELI5: How does a flash bang work? Does it actually blind a person, or cause impaired hearing, or both? | Always been curious as to how these things worked. Not just because of CoD, but because of a friend who entered the army and talked about them.
Edit: Wow! I did not expect these types of great responses. A huge thanks to /u/Moobs_like_Jagger for his excellent explanation on the finer aspects of a flash bang. And being tazed along with having experiences with peeper spray. Very entertaining to read about. | 1,920 | it's very bright. it temporarily blinds the eyes. there's nothing much you can do about that. it's basically like if you shine a really bright LED flashlight into your eyes or look into the sun for a bit (DO NOT TRY!)
it's very loud. 170-180db loud. a pistol gunshot is about 140-150. the decibel rating system is logarithmic so 170-180 is over 100 times louder than a gunshot. | 1,082 |
Why does our bodies get stiffer as we get older? | Basically the title. | 24 | As we age, the elastic-y proteins in our tissues and joints (namely collagen) slowly break down, causing skin to get wrinkles and sag and joints/muscles to get stiffer. This is paired with the commonality of arthritis in old age, which is when the connective tissue that cushions our joints wears down and causes bones to even scrape against each other in severe cases. | 11 |
ELI5: How does the human body know when it has reached growth or developmental stages? | How does the body know when it's time to start puberty, or when to stop a growth spurt, for example? A lot of these things are pretty hereditary, so presumably it's mostly genetic rather than environmental, but how does the body measure time? How does it know "this is tall enough"? | 80 | It doesn't. There are no countdown timers in your body that signal when certain developmental steps should start or end. It's just feedback loops and certain processes triggering other processes.
Let's consider height. During childhood, your bones are able to get longer because they have growth plates at the end where new bone can be formed. As long as those plates are there, the bone will keep getting longer. During puberty, one of the processes that gets triggered is the closure of the growth plates. At the same time as the closure happens, you also go through your pubertal growth spurt. Now it's a race over how much growth you can achieve before the plates close. So you don't stop getting taller because you hit some predetermined height, you are as tall as you are because that is when the plates closed and you couldn't grow anymore. | 23 |
How is facebook exploiting me? | I keep reading it in memes and all over reddit. How? Thanks! | 44 | Basically anything you submit to Facebook becomes their property; Pictures, personal information, everything.
People complain about privacy and then go and spill every single detail of their life to Facebook, thus Facebook is "exploiting" idiots. | 23 |
ELI5: How can gravity exert a force without expending energy? | Every other thing in the world, if you want to accelerate it, you need to spend energy. But not gravity, which pulls distant objects like meteors down without spending any. Doesn’t this violate the 2nd law of thermodynamics or something?
EDIT: Thanks for all the great answers and discussions! Apologies in advance if I can't reply to them all. | 171 | > Every other thing in the world, if you want to accelerate it, you need to spend energy.
This is not true. Something with a positive electric charge will accelerate toward something with a negative electric charge. No energy input required. Acceleration does not require energy. Kinetic energy is a function of *velocity*, not acceleration.
People here talking about how gravity is a special force (it is) are missing the point. Even from a Newtonian understanding, nothing is being violated.
Think of it this way. You can’t get free energy from gravity. Sure, gravity can make an object go fast… as long as you first spend energy to lift the object off the ground. The kinetic energy all comes from the gravitational potential energy that the object started with.
Edit: to clarify, no energy *input* to the system is *required* to have a constant acceleration. An object accelerating in a field by changing speed (not just direction) does gain kinetic energy… but loses potential energy. Total energy is the same. You *can* spend energy to get acceleration (like burning fuel in a car), but forces like gravity and electromagnetic force can produce acceleration just from an object being in the field.
I guess it might be clearer to say that objects in the field always had potential energy to begin with, so if the force causes the object to lose potential energy, it gains kinetic energy. But the force can also make an object “lose” energy, for example, a comet that was already moving at high speed *away* from a planet gets slower as the planet’s gravity pulls on it. It accelerates, but *loses* kinetic energy (by gaining potential). | 202 |
[Halo]How did the forerunners 'fake' human prehistory? | To clarify, as far as I can understand, ancient humans were obviously de-evolved by the forerunners after their war. But, what I don't understand is how did the humans that rose up afterwards, not notice anything odd; Because in my mind, that would imply to me that the forerunners were able to plant fake fossils or something like that to throw off the next iteration of humanity, since they would inevitably rise up again.
So, in short, did the forerunners do anything to make the humans oblivious to their past, or is there a plot hole in regards to this? | 25 | The majority of the forms the Forerunners devolved ancient humanity into had already existed earlier in mankind's evolutionary chain. A few were mutations but from a historical perspective that would just like a species diverging with a few missing links.
Before activating the Array, the Forerunners covered every life-bearing planet they could find with a substance called Solute. Its purpose was to ensure that every lifeform affected by the Array (which is pretty much any animal with a nervous system more complex than a starfish) would disintegrate into its component molecules. No bodies, no bones, no fossils. This was done to prevent an ecological disaster across the galaxy. Having billions of rotting bodies all at once would not be good for any environment. However it had the secondary effect of potentially muddying up a fossil record as it would leave gaps between species that would never be filled.
On Earth, it wiped out the species of humans not already indexed by the Forerunners -homo sapiens, homo neanderthalensis, homo floriensis, denisova hominin and a few others- and, for the most part, any trace they'd ever existed as it takes about 10,000 years for organic material to fossilise (where it would then not be affected by the Solute, thus explaining why there are still dinosaur fossils) and it was only around 9,000 years from the end of the war to the firing of the Array.
Also, while the Forerunners were de-evolving humanity, they also took the time to physically dismantle every trace of human civilisation they could find. They pretty much erased almost all physical evidence that it had ever existed, save for a handful of ruins on some remote worlds. Absolutely nothing was left on Earth. | 21 |
I've seen alarmist TV shows making conspiracy theories that "Fort Knox is actually empty" . Would that even have any actual economic implications? | 41 | > Would that even have any actual economic implications?
Short answer: No.
Long answer: The US gold reserves (310 billion USD) are about 1.6% of GDP (19.4 trillion) and about 1.4% of total national debt (22.4 trillion). The gold reserves correspond to less than two weeks of the total economic output of the US, and about one month of the total yearly gov't revenue (3.6 trillion). If all of the gold reserves vanished overnight, the debt/GDP ratio would go up from 108.0% to 109.4%. Not a big deal. | 47 |
|
ELI5 what is dynamic programming? | I’ve been encountering problems lately where the solution requires a dynamic programming solution, but I can’t wrap my head around how that works. Can some ELI5 it? | 60 | Dynamic programming is a way of breaking problems up into repeated subproblems, then solving the subproblems from the bottom up, reusing any answers that you’ve already figured out.
Consider a naive recursive Fibonacci function:
```
fib(0) = 0
fib(1) = 1
fib(n) = fib(n - 1) + fib(n - 2)
```
I’m on mobile so I’ll use notation “fn” to mean `fib(n)`.
f5 = f4 + f3
f5 = (f3 + f2) + f3
Now I’ll expand the f3 calls.
f5 = ((f2 + f1) + f2) + (f2 + f1)
Now I’ll expand all the f2 calls.
f5 = (((f1 + f0) + f1) + (f1 + f0)) + ((f1 + f0) + f1)
Now let’s look at how many times fib got called.
- f0: 3 times
- f1: 5 times
- f2: 3 times
- f3: 2 times
For f0 and f1, this isn’t a huge deal. But we had to calculate f2 twice more than necessary and f3 once more than necessary. This is ok for `fib(5)` but it won’t be ok for `fib(100)`.
Since the nth Fibonacci number builds on the last two, and this logic will unroll all the way down to 1, we should only need to calculate fx once for each x less than n.
```
fib_dynamic(n):
if n is 1 or 0 return n
fibs = [0, 1] // fibs[x] represents the xth Fibonacci number
for i from 2 to n, inclusive:
fibs[i] = fibs[i - 1] + fibs[i - 2]
return fibs[i]
```
Try out fib_dynamic(5) on pen and paper and see the difference.
With this method, we don’t have to repeat any work because we saved the intermediate answers to be used again.
There exists another technique very similar to dynamic programming, called *memoization* (yes, that’s how you spell it), where you essentially save the results of each function call, then the next time that function is called with the same arguments you can return the saved version. This is often a little bit easier to implement because you don’t have to change your algorithm to go bottom-up, the stack will do it for you.
```
cache = [0, 1]
fib_memo(n):
if cache[n] exists, return it
cache[n] = fib_memo(n - 1) + fib_memo(n - 2)
return cache[n]
```
Try this one out on pen and paper too, see how it compares to the other two. | 67 |
ELI5: Why, after taking long showers, do we feel dried out? What makes the moisture leave our skin? | 130 | Imagine an extremely hot and humid day. Once you step outside, you'll be drenched in your own sweat immediately.
Being in a hot shower/bath/pool is almost the same environment. You're still sweating large amounts but you don't feel it because the sweat is washed away immediately.
Since you are losing water through sweat during the shower, you feel dried out. This can be dangerous if you stay too long in the shower/pool because being in water reduces your sense of thirst and you can get dehydrated. | 77 |
|
I can't shake the stereotype that the American South is still filled with racism and backwardness. CMV | First off, I absolutely know this view is wrong; I have visited a few places in the south, have relatives who live there, friends from that region I love and appreciate, etc, and I do NOT mean to offend anyone or slam anyone, so I'm sorry if I have, but I can't help that every time I think of the south I associate it with racism, homophobia, extreme conservatism, and general backwardness and lack of education. Heck, I almost offend myself with how this stereotype still pops up in my head. I think it is a result of how negatively the south has been portrayed in history (Civil War, reconstruction, Jim Crow, etc.). Logically, I know it's wrong, but I'm looking for some people to help me change my gut reaction to the south. Thanks in advance! | 17 | Stop thinking North vs South and start thinking Urban vs Rural. Major urban centers are generally more progressive in every way than rural areas. It's just when you think of the north you think of NYC, and when you think of the south you think rolling Alabama cornfields. Think of Atlanta instead. | 31 |
[Harry Potter] Could a wizard conceivably make it into low earth orbit, board the ISS, and return to Earth safely using only spells, potions, and magical apparatuses (e.g. a broomstick)? | Assume Apparating onto the station is prohibited, and any restrictions on Wizard-Muggle contact don't come into play.
What sorts of spells etc. would a wizard need to employ to reach the ISS safely, and how long would it take on a broomstick? | 198 | I believe so. We don’t know all of the different spells and potions that exist, but given that it was possible for wizards to travel to the bottom of a large lake we know that there’s some magic that can allow wizards to endure harsh environments.
They’d probably just need something that obviates the need to breathe, protects them from the harsh conditions of the atmosphere, and increase the speed and momentum of their broom enough to reach the station. | 110 |
ELI5: Why is/was the federal mail service (USPS) in debt and on the brink of financial failure, while independent services (UPS, FedEx) remain profitable? | 53 | Congress got it in their heads that since emails became popular and would only become more popular, the US Post would eventually have a lot of problems staying profitable. Worried that a majority of their workers would retire at the peak of people no longer using the Post Office, they said that the USPS needs to make sure to have enough money for all these people's retirement funds and pensions NOW, before the plunge happened. | 63 |
|
[Overwatch] How does Sombra hack things? | She seems to just be some odd tech-guru that would even leave Technomancers scratching their heads. When she was younger, she seemed to have to be in physical contact with a computer, but now she has all this fancy holograms and stuff, so any ideas on how it all works? | 16 | For most of the combat "hacking" it's probably less of an actual "hack" and more like a brute force overload that takes the targeted machine a few seconds to compensate for, or the owner a few seconds to troubleshoot/repair. The only really innovative thing is probably her ability to affect things that should be airgapped but even then. It would explain why it's so close range and why it doesn't last very long. For everything else, like the medical pickups and the shenanigans at the robot factory, she probably has backdoors. | 20 |
[Doctor Who] How are the Weeping Angels not breaking the laws of time, by sending people from the present into the past they are giving them the chance to change history with their future knowledge thus breaking the very rule that the Doctor keeps harping on about? | And this is going on a lot. | 432 | I mean, they are. They just get away with it.
It's like going "Why is that person speeding? That breaks the laws! He could cause a lot of accidents and make problems for everyone!" Yes, the Weeping Angels do things that can cause paradoxes and mess with the fabric of time. They're BAD. | 454 |
[marvel] can someone explain how a human can breathe with an Adamantium ribcage? (the ribcage needs to move with the lungs) | 445 | How does *your* ribcage move? Bones don't flex.
The ribs may be adamantium, but the cartilage and tendons which connect it together are not. That is what allows a ribcage to flex, be it bone or indestructible metal. | 538 |
|
CMV: We need a world-wide moratorium on viral Gain of Function research and to place strict restrictions on DNA synthesis. | This CMV is NOT about covid. I will not speculate as to the origin of SARS-CoV-2 except to say that the possibility of it having been leaked from the lab has [not been dismissed](https://onlinelibrary.wiley.com/doi/full/10.1002/bies.202000240) and there are [more](https://www.science.org/doi/10.1126/science.abj0016) and [more](https://www.technologyreview.com/2021/05/13/1024866/investigation-covid-origin-wuhan-china-lab-biologists-letter/) articles from reputible sources to that effect.
This CMV is as clear as the title:
**We need a world-wide moratorium on viral Gain of Function research and to place strict restrictions on DNA synthesis.**
Here is my reasoning:
* This outbreak was NOTHING comapred to what it could have been. SARS-CoV-2, for all the harm it has caused, is a wimpy virus. H5N1 is 70 times more lethal and the measles is 20 times more infectious.
* Without going into details (but I could if desired), it would be fairly trivial to combine the features that make those viruses so deadly/transmissible with the SARS-CoV-2 trick of disabling your innate immune system so that you're spreading disease weeks before you're symtomatic... It would be a virus that spreads without you knowing your sick, spreads basically at will, and eventually kills the vast majority of those it infects. The hospitals would be instantly overwhelmed. I'm not even sure where we'd put all the bodies.
* There are at least 4 ways this supervirus could emerge:
1. Naturally in the wild (least likely)
2. From the resevoir of SARS-CoV-2 currently mutating in the human population
3. Gain-of-fucntion research
4. It could emerge on purpose from a terrorist or religious organization that, for whatever reason, wants to bring about the end of the world. Hell, it could emerge from a disgruntled grad student.
* We have the technology to engineer such a virus and have had it for years. I estimate it would take a single average mol bio grad student half a year to accomplish this. Regardless of timelines, this can be accomplished with today's technology and this will only become easier as our mol bio tools improve.
* Gain of Function (GOF) research has a spotty track record in terms of safety and utility. There were calls to ban it [as early as 2013](https://www.nature.com/articles/495411a) when some researchers became alarmed because [the cost/benefit ratios of the research were unacceptable](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4099557/). We now know that viruses similar to SARS-CoV-2 were being worked on under totally inadequate safety conditions (BSL2) in Wuhan. We also know that GOF has been previously performed on H5N1 to make it more transmissible.
* Virsues escape the lab all the time, [both in China and the West.](https://www.vox.com/future-perfect/2019/3/20/18260669/deadly-pathogens-escape-lab-smallpox-bird-flu)
* DNA synthesis is poorly regulated today. The most challenging part to making a novel virus is obtaining the synthetic DNA. This is becuase many comapnies that offer this service will routinely compare the sequence ordered to a database of known pathogens. So that should make us pretty safe, right? Wrong. There are literally 1000s of unregulated labs around the world that either have or could easily obtain the capacity to make their own synthetic DNA without any sort of regulation. You could also order the building blocks of synthetic DNA from the established commerical suppliers and assemble your plasmid DNA yourself (you'd have to be clever about this but it's doable).
* There are groups today and certainly more in the future who welcome the end of humanity. These range from death cults, fatalist religious groups (ex. Aum Shinrikyo), and terrorist organizations who'd love to [hold the world hostage](https://i.pinimg.com/600x315/2a/d6/3f/2ad63f0f2333d5bc0e423689f90ef38d.jpg).
We need to treat this problem with the same or greater seriousness as we treat nuclear proliferation. We need to prevent anyone from obtaining DNA that corresponds to existing or novel pathogens. If we fail to do this, covid is going to look like a blip and it's just a matter of time.
**Why I want my mind changed:**
Becuase if it cannot be, then we are in a scary as hell position with our pants already down and our chin already bloodied.
**To change my view:**
Make a convincing argument that one or more key point in the body of the argument is not true. | 15 | So how would scientists understand virus and figure out ways to get a head of the curve to prevent another pandemic events and create vaccines for them?
​
If they don't fully understand the nature of the virus how can they make vaccines and how can they create any predictive models to try and stay a head of any mutations to keep the vaccines effective? One of the many aspects of GoF is learning about the virus and how it might mutate and to be able to develop vaccines to resist these mutations before they get out of control. | 12 |
I believe that the Federation's laws against genetic enhancements are ridiculous. CMV | First of all, for those of you who do not know, the controversy in the Federation about genetic augmentation spawned from "the Eugenics Wars" in the late 20th century Earth. Some augmented super humans took control of the world from the shadows, and were probably responsible for most of the wars throughout the 21st century leading up to WWIII. The most powerful of these augmented Tyrants was Khan Noonien Singh. I think having laws in place barring the improvement of living beings based on an event that happened almost 400 years in the past is an obsolete way of thinking. The Federation is the champion of individual rights and libertarian values, so the right to improve ones self through genetic augmentations should not be infringed upon by the state. Individual determination has always been the central ideology of the Federation, and this ban is nothing, but a disgrace to what the Federation stands for.
Some of you may argue that augments are naturally violent and egotistical. Spock said "Superior ability breeds superior ambition," and I find it laughably ironic that a Vulcan would be the one degrading human augments. Vulcans are physiologically stronger and smarter than humans, rivaling even augments, yet the Federation doesn't ban Vulcans. The idea that the ban on augmentation revolves around the assumption that all genetically engineered people are all going to end up like extreme egotistical elitists has been proven false by the countless different species within the Federation, all with different levels of strength and mental capability living in almost perfect harmony. Vulcans are a prime example of this.
My third issue goes back to civil liberties and equality again. What if I was born a human, and decided that I'm a Vulcan trapped inside a human body. So I want to change my genetic and psychical structure to that of a Vulcan (kind of like a sex change). The Federation should not legally deny me this opportunity. By prohibiting the right to change oneself for the better or worse, the Federation is thereby making itself a less free and equal place. Why should I be born in a body that is weak and feeble, while my neighbor T"vok gets to live to 200, has psychic powers, and can lift 2 tons effortlessly. Its unfair to say the least.
| 166 | Julian Bashir provided an alternate argument against genetic enhancement, analogous to those used against performance-enhancing drugs on Earth in the pre-warp era. If genetic enhancement for children became the norm, parents would be pressured to have their children genetically engineered as well, just to keep up. Twentieth-century Earth explored the dehumanizing effects of such an outcome in the film "Gattaca", among others. That's not to mention that genetic enhancement is inherently quite risky and can have serious side-effects. For these reasons, genetic engineering remains illegal so that it doesn't become a necessity for success. | 32 |
ELI5: With UAVs being common throughout the world, why aren't there many unmanned ground vehicles (UGVs) being used for military applications yet? | 76 | It’s easier to navigate when there are no obstacles, so the ocean and the air is simply easier for unmanned craft to manage. With modern developments in ML that’s changing, but it’s a fundamentally harder problem being *in* the terrain than over or under it. | 176 |
|
CMV: Saying all White people are racist is racist/bigoted | Firstly I'd like to point out the title says "racist/bigoted" due to differences in how we define racism, younger generations believe there has to be a systematic element where as older generations will not need this element to be present.
So. I've seen numerous times, mostly from the left, people argue that all white people are racist. Now to call someone racist you are making a statement about that person's beliefs/opinions and their behaviour.
So, by saying all white people are racists you are saying if you belong to this race or are from this bloodline then you automatically hold (X) beliefs and exhibit certain negative behaviour. That is downright bigoted and, depending on your definition, racist. | 763 | How would you feel about the idea that all people are racist? Everyone makes prejudicial assumptions based on appearance, even if subconsciously, and after sex, race is generally the first thing we notice about someone.
This is just how people work; we’re very visual creatures. It’s not anything to feel terrible about, but if you’re stuck on believing we’re not wired to judge people based on appearance, your not going to be able to correct for any of this inherent bias. | 346 |
ELI5: What is the reasoning behind how trains are loaded? | I see trains everyday and I’ve never understood how/reason behind how rail cars are organized. I see 3x fuel cars then 2x box car, and finally more fuel cars. Why not all the fuel cars then box cars? | 23 | They are generally arranged by how they are picked up and delivered. It's much easier to pull into a place and unhook the last five cars, then go to the next place and unhook the next 8 cars, etc., then to have to go to each place, unhook cars 1-6, and cars 7-12, then connect to cars 7-12, then move them, then disconnect them, then reconnect cars 1-6, then reconnect the rest of the cars, etc. | 34 |
Feasibility of warp drive under M-theory | 82 | TL;DR *If* there are compact extra dimensions and *if* you have the ability to change their radius by factors of trillions and *if* you have access to several Jupiters worth of antimatter and *if* you can get a negative mass-energy density, *then* you can get a working warp drive. | 38 |
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CMV: Considering the majority of society aren’t adequately educated on the criminal justice system, jury trials are an ineffective way of delivering justice. | For example, if somebody is facing the death penalty or a life sentence, it is unfair to have someone’s life hanging in the balance of legally uneducated people. Surely legally trained professionals are far more capable of deciding whether somebody is guilty beyond a reasonable doubt. Letting someone’s life be shaped by a group of people who most likely have no education on legal matters puts defendants at a disadvantage. Most people use their judgements on gut instincts or prejudices instead of following the way the law works. | 116 | The job of a juror really doesn't require much legal knowledge. You really only need an in-depth understanding of the law in order to know what to charge a person with or how to make a case for or against them, which is why lawyers are responsible for those parts. A juror's job is not to interpret the law at all but only to look at the evidence and arguments before them and judge guilt or innocence. The judge will inform them the crimes the person is charged with and what each one entails, and that is really the only legal knowledge they need. One doesn't have to go through law school in order to determine whether someone broke the law or not.
>Most people use their judgements on gut instincts or prejudices instead of following the way the law works.
That's why we have a jury of 12 people and require them to agree unanimously, because it's highly unlikely all 12 people are going to have the same exact prejudices or instincts. They debate the evidence among themselves, which helps to moderate any one person's opinion and come to the most logical final conclusion. | 39 |
ELI5 Why can't each state run the voter rolls through the SSA death index database to get rid of the 'dead people who vote'? | 235 | (1) They should.
(2) The SSA death index isn't always 100% accurate (though it should be), and people get very upset if a single voter is denied access to the polls.
Further, any attempt to clean up the poll books is met with accusations of deliberate voter suppression. (Some of them might actually be attempts at voter repression, which complicates things even further.) The result is that the poll books remain highly inaccurate (out of date). | 79 |
|
[DCEU] Why did people hate Superman when he was alive but love and mourn him when he was dead? | Throughout Dawn Of Justice, and I think during Man Of Steel(I haven't watched that one in a while), Superman was something of a pariah, people hating and fearing the power at his disposal and even the government themselves wanted to bring him in dead or alive. But in the Justice League movie, after his sacrifice against Doomsday, people started loving him, calling him a hero and a symbol of hope, even building enormous memorials in his honor. What gives? What made public opinion on him switch at all but the drop of a hat? Also, when Superman was revived in Justice League, did people go right back to hating his guts? | 18 | Dying is always the best PR move, and in a heroic sacrifice against a giant monster? Plus the fact that he *died* proved that he wasn't a god, just a powerful man, which quelled a lot of people's fears and criticisms of him. | 23 |
ELI5: Why are domesticated cats generally so afraid of water yet wild cats like pumas, lions, etc. regularly cross rivers, lay in the rain, and don't seem to be bothered by it? | 39 | It has a lot to do with the nature of their fur. Domestic cats get soaked in water, and really lack the lose skin and shaking reflex of a dog. Other animals have guard hairs and oils that keep the inner fur dry.
If you wash a kitten in warm water, dry it straight after, it will not mind this - it doesn't link getting wet with the unpleasant effect of getting getting very cold. If a cat's first experience with water is something like trying to run across a weed-covered pond - well, it will be paranoid for the rest of its life. | 22 |
|
ELI5:Why don't we see riots in Belarus, when there are riots in Ukraine? | The latest riots in mainly Kijev has been triggered by heavy russian influence in the country, and the pinching between Russia and EU.
This leads me to think: wouldn't that imply, that this dilemma between staying Russia-influenced or moving towards EU would move on to a country like Belarus. It's known as the last dictatorship in EU, and is stuck in a bit of a limbo like Ukraine. I suppose that eventually there will be a heavy pressure to open up towards west, but why aren't there any rumblings in this country? Is it because that the opposition is more oppressed than in Ukraine, or are the people of Belarus keen on staying a gated country and leaving progress behind? | 15 | Belarus was already effectively a dictatorship, and the government would never, ever have permitted a protest movement to develop and take over a public square for months. They'd have sent in the military on day one. And everyone living there knows it.
So there's no protest movement. But hey, the situation was similar in places like Libya, Egypt, etc, so who knows what could happen given time? | 10 |
ELI5:Why is that animals can sense things like earthquake before they happen while were left totally clueless? | 29 | Earthquakes produce two kinds of waves, P-waves and S-waves. P-waves travel faster through the ground than S-waves, and aren't destructive, or even easily noticed by humans.
The leading theory is that some animals can sense the minor vibrations caused by the P-waves, which alert them to the incoming S-waves (which are what cause the damage from the earthquake).
As a side note, we have the capability to build P-wave detectors which can give warnings as early as 60-90 seconds before an earthquake hits, depending on how far the hypocenter is. It's enough time for people to seek shelter and for certain dangerous systems to shut off, such as trains and natural gas pipes. | 25 |
|
How are Calcium(+2) ions able to form ionic bonds with 4 atoms at once? | How would this affect the overall charge of the molecule? I understand that calcium has a +2 charge, but when observed in structures such as calcium hydroxyapatite, it is able to bind to up to 4 oxygen atoms. Similarly, other alkaline metals such as Magnesium(+2) are able to bind to EDTA with the same 4 bonds occurring. HOW???
edit: wording | 15 | Even worse, Ca2+ is octahedraly coordinated (6 bonds) in lime!!! The reason this works is because the attractive part of an ionic bond is essentially just the Culomb force. Since this force is omni directional the energy of an ionic system tends to be minimised when as many anions (Or in the case of EDTA, negative charge centers) as possible are in contact with each cation. So long as each region of a substance is charge neutral (roughly meaning that every shell of anions is surrounded by a shell of cations) the attractive potential will tend to dominate the repulsive and thus the system will tend to be bound and stable.
This principal is actually verry important in predicting/explaining the structures of ionic compounds where it is called the first Pauling Rule | 14 |
[Invincible] So did Urath never contact the Coalition of Planets where their evaluator was? | Allen the alien has been going to Earth for fifteen years, where an evaluation hapen every three years, so Urath missed at least five evaluations and never asked the coalition where the evaluator was? They can obviously contact them because they need that to start the mandate in the first place. | 16 | It's possible Urath didn't know what the schedule of evaluations would be. Given there are species out there that can see multiple decades as a pittance in terms of lifespan, it might not have registered as odd that no one came to fight them for 15. | 20 |
ELI5: The significance/obsession of USA citizens with prom and high school graduation. | Is there something that I'm missing here?
I thought it's normal to finish high school and prepare to go to pre U than Uni.
But after seeing limousine being rented, hundred plus USD dress, another hundred plus USD for shoes, and top that with another couple of hundred USD for other necessary stuff, I'm questioning my own logic.
It doesn't stop there, it seems, graduating high school is widely celebrated even to a point that parents give out paid vacation trips or a car as gift.
As for the students theme self, OMG they spent months preparing for prom and the fight for Queen and King is actually real. I thought it was just TV shit.
Back to the question, why? what is it I'm missing here? | 52 | TL;DR: We've lost most of our developmental milestones and coming-of-age rituals. So high school prom and graduation are a major milestone for most people, often the *only* milestone. They're an important cultural event and ritual that signals a transition from childhood to adulthood. People want to mark the occasion and remember it later in life.
The US, like many Western societies, is gradually secularizing. It is also highly urbanized. And finally the cultural importance of marriage and the nuclear family has been declining for decades. As such, we've found that many of our developmental rituals have faded away.
In many religions, there's some type of coming-of-age ceremony. Jews have bar mitzvah at age 13. Many Christians have Confirmation around the same age, where children are taught important theological points and are allowed to take communion at church for the first time. Lots of cultures have various rituals and ceremonies for the time when a child is perceived to have become mature and able to take on adult responsibilities and privileges. These ceremonies aren't always religious, but in America, historically, they have been. Most people in America, even if not personally religious, have a Christian background. But religion has faded greatly from public life. Most people rarely go to church, if at all, and a sixth of the US population has no religion. So religious coming-of-age ceremonies are gone for many people.
Second, we have urbanization. Rural areas tend to be "old-fashioned." Traditions are stronger. There's a variety of reasons for this. Part of is it the closeness of communities. In urban settings, you can be alone, you can get lost. If you have no interest in keeping up traditions, there's no local authorities: familial, religious, or economic, to force you to keep up with tradition. If you stop going to church, stop wearing traditional clothes, stop going to holiday gatherings and other ceremonies, no one's going to notice. But in rural settings, people rely heavily on one another, and you'll be gossiped about heavily if you're an oddball who doesn't keep up with tradition like everyone else. So you do. Rural areas often have all kinds of gatherings and rituals, especially for children. Barn-raisings, harvest festivals, Christenings for babies, and especially early marriage. In old times, in rural places, people often moved straight from their parents' house straight into a new home with their spouse. They married at 19 or 20 and started having kids immediately. Weddings then became a huge deal. You kindof weren't an adult until you got married, but there were always the occasional "bachelors" and "spinsters" who delayed marriage or never married. This has gone away. The average age when a woman first gives birth now is 27, compared to 22 a century ago. And marriage is delayed as well. We now give weird looks to people who marry before 21. That used to be about the average age people got married. Now it's not abnormal to wait until you're in your 30s to marry and have kids. | 57 |
[Aliens] Why are alien planets *always* unified politically? | Every time I see a sci-fi in which another planet is shown, there's always just one government ruling the whole planet and no other political divisions. Given that has never happened in the history of the earth, why do we assume that it'd happen on other planets? Any examples of a sci-fi alien planet that has multiple nations on it? | 371 | In startrek most races have conflicting political parties. That being said they still act in unison for the most part when attacked by outside forces. An example of this would be the Klingons. They have a consul of honorable families that have power and there own political goals. That being said most scifi that deal with aliens race seem to assume that by time you are capable of FTL travel you have created a society that can at least unite your planets political parties. | 328 |
CMV I believe /r/news and /r/worldnews should ban links from FoxNews.com and anything related to Fox News | Why I'm in favor of this:
Fox News has repeatedly been shown using biased reporting and reports pseudo-science constantly. They are nothing more than a spokesman for the Republican party. I'm not saying that Fox News can't report the truth, but most of the time they don't. Or they distort it to meet their own agenda.
Take for example when they were covering the Boston Bombings. Several members of their news team/guests were advocating for taking away the constitutional rights of Muslim Americans. Ann Coulter even suggested that the bomber's wife should be in prison for wearing a hijab.
They lie about global warming and claim that more CO2 is actually better for us. They lie about Benghazi even though we now know no "stand down order" was given.
So I believe that /r/news and /r/worldnews should ban links from FoxNews.com. The sources may be distorted to meet their own personal goals. While I'm not saying that this makes MSNBC better than Fox, they're not going around talking about destroying the Constitution for anybody they deem unworthy. | 20 | To specifically cut out Fox News would imply that they are the only ones guilty of biased journalism. People should check *all* articles and news reports for bias. Don't let your guard down just because it's not Fox News. | 30 |
How did we come to know that our galaxy is spiral? | 58 | There are a number of factors.
Partly because lots of other galaxies are spirals, and the difference between spiral and elliptical galaxies is quite pronounced, in terms of the types of stars they contain.
Plus the Milky Way looks like a disc-shaped thing plus a bulgy thing in the middle from side on.
And nowadays, we can use parallax, doppler shift and all that to make a 3D model of the Milky Way, and the arms and bars are clearly visible. | 29 |
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What do Kierkegaard and Hegel mean by infinite absolute negativity? | I was reading Kierkegaard’s “The Concept of Irony: With Continual Reference to Socrates”
and couldn’t find any sources to unpack the Hegelian definition of irony. Can anyone explain it to me like I’m five? | 83 | Maybe this? "Infinite Absolute Negativity": Irony in Socrates, Kierkegaard and Kafka Author(s): Reed Merrill
Source: Comparative Literature Studies, Vol. 16, No. 3 (Sep., 1979), pp. 222-236. :
“…Infinite absolute negativity fully expresses Kierkegaard's dialectic of opposites, and irony provides the mode of its presentation. To Hegel, infinite absolute negativity is the meeting of opposites - negatives merging with negatives - the result being evolution to new and higher levels of improvement in historical time. The term is meant to
be positive and integrative; it describes the Hegelian moment, according to Emanuel Hirsch, "in the dialectic of the Idea, the Idea which negates itself and through this negation emerges as the true affirmation." For Hegel, irony was only a mechanical device serving positive ends. …” | 19 |
[IT] Can IT eat unsalted meat, AKA, "fearless"? | So fear salts the meat, according to Pennywise. But a person can eat unsalted meat, it'll just be bland.
If confronted with people who don't fear It, are they just bland, or impervious to being attacked?
If they can be eaten without the neccesary fear, why not kill them at It's convenience? | 30 | Yes. It's fully capable of killing people without terrorizing them first, and it can eat those it didn't properly scare, either.
However, people that don't fear it have the capability of turning their belief and conviction against it, and using those psychic weapons as very potent methods of injuring, if not killing, it. So it's usually in the entity's best interest to keep potential victims afraid and incapable of rationally thinking.
So it's a combination of taste preferences as well as basic self-preservation. It could easily sneak up on unsuspecting humans and eat them, but there's no sport and no seasoning. And if others get wise to it without being kept under a terrifying mental sway, they'll be too vigilant and ready to fight back. | 32 |
ELI5: What Is Stoicism? | 17 | I believe it’s a philosophy from the Ancient Greek era that preaches ideas along the lines of ‘don’t concern yourself with what you cannot control’ and that you are in control of how you react, your emotions etc. | 38 |
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Two offers for an Assistant Prof. in Engineering. What start up resources should I request? (also AMA) | So, I am currently in negotiations with two schools for a position in an engineering department. Both are top 30 schools (one is ranked much higher than the other). They both know that I am getting an offer from the other school, so they are trying to offer a competitive package.
My problem is that is my research is all theory/computational and I don't feel that it really requires much. I've asked for money for students/postdocs and for buying computational resources and a small amount for incidental expenses.
What else should I be asking for? Is there anything you wished you asked for when you negotiated a new Asst. Prof. position? I'm sure it becomes clear what you need once you actually get your research group going...
EDIT: I applied to ~25 schools and got 8 campus interviews. Happy to answer questions about the process if you are thinking about applying. It was more depressing than I expected, even though I am happy (and relieved!) with how it is ending up.
| 27 | Don't forget to ask for money that can be used for:
* Books
* Memberships to professional organizations
* Travel to conferences
* Registration for professional institutes/training sessions/etc.
* Supplemental summer income and/or course buyout for research purposes | 13 |
ELI5: How can scavenger animals (that feast on often diseased, rotten flesh) stomach such meals? | What makes their digestive system so unique that they are classified as "scavengers"? | 11,029 | In addition to highly acidic stomachs, scavengers also have short digestive tracts. Their food spends less time in their body\*, so whatever may have survived the stomach has less time to multiply in the intestines and become a problem.
\*they can afford this because rotten meat is basically pre-digested. Tenderized. | 9,507 |
Why does Starkiller use a reverse grip? | Starkiller's training came from Vader (who used a standard grip) and a combat droid using simulations of dead Jedi, most of whom would have used a standard grip. Why did he chose to use a fighting style that he likely had next to no training material on to work with? | 25 | Marek was originally trained primarily in Form V, which is all about creating your own openings, acting unpredictably and keeping the opponent off-balance. The reverse grip (despite the decreased versatility and possible health risks of introducing your forearm to your lightsaber in while in combat with a physically superior opponent) helps by throwing the opponent off balance, given how rare the unorthodox grip within the form is (partially natural selection, since you're exposing your front. If you don't have the agility for it, squish!) for a Jedi to run into.
Vader didn't use it because he wasn't agile enough - his entire combat style was focused around bringing his enormous physical strength to bear and working around his own limitations. But for someone like Starkiller, designed specifically to kill Jedi and kill them fast? Oh yes. Very nice indeed. | 39 |
[Doctor Who] Did the Tardis originally come with a Perception Filter installed or was this added later to compensate for the broken Chameleon Circuit? | 49 | I believe this is a standard feature. The primary function of a TARDIS is to allow timelords to travel to other worlds and observe them without disturbing the inhabitants.
The camouflage features are there to protect the place it travels to, not the Tardis itself.
As well as the chameleon circuit and the perception filter, the tardis navigational circuits include a feature which looks at the landing site selected and will do a last-minute adjustment of the co-ordinates so it materialises out of sight. Of course, like many features in the Doctors tardis, this only functions intermittently. | 40 |
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ELI5: How are impurities and other garbage taken out of the water inside sewer systems, and what happens to the waste after the water is cleaned? | 18 | I went to a waste treatment plant several years ago and this is what happened:
* The water flows in and is run though a gate. The gate picks out most of the larger stuff, and the flow of the water is slowed occasionally to allow people to clean out the gates.
* Then the water is run through a grate. Sometimes the water will be run through two or more grates. This will pick up the solid stuff and non-dumpable things that get flushed every so often. Your kid's dead fish will get scooped out here as will your lost diamond ring.
* Following the grates, the water flows through at least one, and maybe more screens. This is the first stop where your poop gets filtered out. It also filters out condoms, tampons, toilet paper and whatever else gets flushed down. Again, the water flow is adjusted or even diverted to allow for cleaning of the screens. The stuff filtered from the screens may be taken to a landfill.
* Then the water may get held in a pond for awhile. This allows for anything else that may have founds its way through to drop to the bottom of the pond and be scooped out.
* The water, at this point will have bacteria added to it. The bacteria will eat whatever organic material is left and then more bacteria is added to eat THAT bacteria.
* Then you may have the water sprayed over charcoal for one final washing.
| 12 |
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(Pokemon) Is a Pokeball a weapon? | Could you consider it a weapon? | 27 | Not really, the League-approved ones can't realistically cause harm other than blunt trauma. Pokeballs use the low-end of the matter-energy spectrum so there's not much raw energy to work with. You could try to jury-rig the ME ray to cause damage, but most likely you'd run out of battery before killing anything. And really, when you have creatures hotter than the Sun at your command why bother?
Capturing people really isn't an option either. All pokémon traffic is handled by the Bill Cloud, which can't be fooled. If you really stretch it, you might be able to redirect the data into your own system, but that requires too much infrastructure to be practical. | 28 |
I don't believe married, home owning, or procreating people should get tax breaks. CMV. | These three things are all your own choice. None of them help society as a whole. Being a an unmarried renter who hasn't knocked anyone up, it makes me upset that I never get much back on my tax returns (a couple hundred dollars on 40k a year), when I see my friends with kids getting back thousands and thousands of dollars. | 41 | Having children is really, *really* expensive. Without some form of subsidies the only people having children would be people who are 1) rich, or 2) bad at planning/making decisions. There are a lot more people in the second category. | 31 |
ELI5: Why have humans evolved so far as to lose their thick coats but still grow hair on their heads and faces? What purpose does it have? | Just confused as to why we all still grow hair if it doesn't really do anything. | 46 | In short because as humans evolved from arboreal dwelling primates to plains dwelling proto humans it was more important to keep cool, and since we sweat to keep cool those who were less hairy tended to cool off better and hence survive better to pass on the less hairy genes. Hair on the top of the head remained because it was likely an effective sun block, and pubic hair probably had some part in sexual attraction or scent retention. Humans in this environment had dark skin pigmentation that evolved as a natural sun block as hair was lost. Once humans began expanding to cooler climates they had learned to use animal skins, and hairy individuals didn't survive any better than less hairy ones, so humans who moved to cold climates didn't have to be hairy to pass on their genes.
Edit: Also around 10,000 years ago, give or take, humans in colder climates who's skin had less pigmentation were more able to make use the decreased sunlight, and eventually the lighter skin became the predominate skin tone in these climates. | 15 |
[Terminator] Can humanity beat Skynet? | Looking through years of records fighting Skynet bots I've uncovered a pattern in their behavior, they are not "terminating" but toying with us.
Terminators throw people around, miss bullets (impossible for a machine, they wouldn't have fired if they were going to miss) and never going for human weak points like the heart and brain. It's like Skynet thinks it's a Saturday cartoon villain or an 80's fighting movie bad guy.
Since we will not let ourselves die as a species, and Skynet seems like it just wants to play about with it's flesh toys, can we beat it? | 21 | There's really been no evidence that Skynet thinks at all. It's certainly not a Singularity AI, and it doesn't seem to have any sense of self or subjectivity that would lead to innovative thought. It's just a military program run amok, following pre-programmed eventualities and adhering to specific tactics with little adaptability. | 24 |
[Kung Fu Panda] Why didnt Oogway give the scroll to Tai Lung and explain it to him? | Why didn't Oogway just give Tai Lung the scroll and explain the lesson of self-worth? It was, apparently, the only thing he was missing from his training; if Oogway knew that Tai Lung and Shifu had been working towards making him into the Dragon Warrior but missed something crucial (like humility and self-esteem?), shouldn't it have been his responsibility as Shifu's master to say "Hey, you're missing the point of *excellence of self*"? Philosophy and fate and the illusion of control aside, his actions seem fairly arbitrary. Oogway saw a darkness in his heart, but never felt particularly inclined to identify or address it? He just said 'no scroll for you, fuck off'? | 30 | When the student is ready, the master will appear.
Contrapoint: if the student is not ready, the master should remain hidden.
In the philosophical tradition Oogway and Shifu were part of, stuff like 'questioning' and 'explanations' and 'just fucking tell him what's going on you secretive old asshole' are pretty much anathema. True knowledge can only come from within. It's the student's job to find his own path to truth, and it's the master's job to guide the student on that path of self-discovery, *not* by telling the student what to do, but by approving or disapproving of the student's actions and thereby showing him whether the path he has chosen is correct. To teach with words is to provide only the illusion of understanding and so sabotage true growth. If Tai Lung (and Shifu) didn't come to realize the true meaning of *excellence of self* on their own, no amount of words would matter. | 39 |
ELI5: How does the air recirculation in car AC work? | Also, is it safe to use the feature for long time? If the air inside the car is always recirculated, won't it be saturated with carbon dioxide as we breath? | 17 | If cars were sealed to the point that one could suffocate themselves by not opening a window, it would be difficult to open your door, and then when you closed it your ears would pop.
Setting the HVAC (Heating, Ventilation and AC) in your car to recirculate just means it will draw the majority of the air it is using to either heat, cool or ventilate the car from the cabin instead of just at the base of your windshield outside. This helps in certain situations. Mostly it's good for when you're using your AC because it reduces the ambient temperature of the incoming air, making chilling it easier for you system. It's also good for when you're behind a truck or some 'bro' rolling coal to stop the fumes from being drawn into the cabin of your car. Also on particularly humid days it can be used to speed up the defogging of your windshield (carry a shower squeegee for this in your car as well, you'll thank me come this fall/winter), and any day with a pollen index warning to stop that from being drawn in. Other than those situations it's fine to use either setting. | 24 |
The Federal Reserve and why some people think it will be better if it's eliminated. | 296 | The Federal Reserve is basically the National Bank of the United States. We used to have an actual "Bank of the United States", until Andrew Jackson decided banks were evil and shut it down (Apparently, he was part of the hipster "Occupy the 1820s" movement).
The Federal Reserve works by loaning money to other banks, like, Wells Fargo or Bank of America. You cannot get a loan from them (Well, unless you own a bank).
One of the big powers of the Fed is the power to set the interest rate on the loans they give. If they want banks to loan lots of money, they set their rate low. If they think banks are loaning too much money, they raise their interest rate.
By making it more or less attractive to loan money, the Fed can indirectly adjust the inflation rate. Inflation too low? Lower your rates. Inflation too high? Raise your rates. (This is a massive oversimplification).
Some people think nobody should try to mess with currency that way, trying to adjust the rate of inflation. They think that the free market will set an inflation rate that is best for the economy, and the Fed is just messing that up. Other people think it's better to have some way to mess with inflation, in case it gets too high or too low. | 181 |
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ELI5: If exercising is good for your heart, why is being overweight bad for your heart even though it works your heart out? | 66 | Copy paste of an old response of mine about high blood pressure :
"Oh you are right, it gives your heart a workout, but not a good one.
High blood pressure means that your heart will need to work harder to pump blood, which makes your muscle heart, specially the left ventricule ones, get bigger and bigger. Problem is that, the more this muscle will get bigger, the more it will take space within the ventricular cavity. Therefore you'll have less space for blood. And in order to not get less blood sent to your organs, your heart will beat faster.
And the faster the blood will get pumped, and because of the high blood pressure, the more blood will get to your right ventricule. And at one point, the volume in right ventricule would be so big that it will deforme the ventricular muscle : your ventricule will be dilated and won't be able to effectively pump.
In the end, you'll end up with a very low functioning heart." | 64 |
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ELI5: No idea if it's crappy design or malicious design, but I've noticed that packaging never wants to tear open where the perforated line is. Why is that? | 21 | Most likely the blade that makes the perforations is either worn out or not adjusted properly, so it just marks the packaging a bit instead of significantly weakening it.
To fix it, the manufacturer would have to regularly take a sample and see if it tears easily where it's supposed to, then stop the production line to fix it whenever it gets close to failing. Stopping production lines is expensive, and QA costs money too. | 17 |
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ELI5: How does a Chameleons colour change work and how does it activate it? Also, is there any colours it struggles with and can it change into colours beyond our visible spectrum? | 41 | Chameleons aren't the masters of color and camouflage - for that you need to go to the octopus, the cuttlefish and the squid.
Chameleon are mostly greens or browns and shift to lighter and darker colors. Some do have red or yellow markings as well and they have UV markings as well. When they get angry or threatened then their color changing goes into overdrive and they go very dark.
But Chameleons are born with particular markings / pattern and they can't change those - their color changing is restricted to lightening or darkening their existing pattern. | 13 |
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Why do cars idle at about 1000 rpm? Why haven't engineers developed a car that idles at or near zero? | I understand that the engine runs on combustion and that must occur to keep the engine running. However, what is keeping engineers from developing a car that brings the rpm down to 0 or near 0 when idling? | 38 | In theory, you can "idle" an engine at 0 rpm if you have a valve train that offers very fine control to the ECU, and a direct injected system (also controlled by the ECU, the fuel injector has its own socket in the cylinder head like a spark plug does). To do so, the ECU just squirts some fuel into whichever cylinder is closest to the top of its compression stroke, while simultaneously firing the spark continuously.
For a traditionally-designed engine, however, there are basically three competing needs: the ability to rev up quickly on demand, the minimum energy required to keep the engine turning without external input (like you get when using the starter motor or engine braking), and the minimum amount of air the engine can suck in at any time.
I think the first two are pretty self-explanatory, so I'll go into more detail with the third. As it turns out, the otto-cycle engine (a gas/petrol engine) is controlled by a process that basically amounts to reducing its efficiency from 100% of its rated power at a given rpm to whatever you want. This is done by closing the throttle valve; this requires the engine work harder to suck in air, due to path constrictions. Your engine is always most efficient at full throttle.
Additionally, for combustion to take place inside the cylinder, the mass ratio of the fuel and air has to be close to ideal. This is called the stoichometric ratio, and basically means that when the combustion event is complete, there remain no unburned fuel molecules or oxygen molecules. For standard gasoline, it's a bit over 14:1 air:fuel, once again going by mass.
It is possible to deviate from this "golden ratio", and sometimes it's even advantageous to. We call a mixture that's heavy on the fuel side "rich", and one that has too much air "lean". Both of these modes are used occasionally by a modern engine's ECU depending on the feedback it's getting from its sensors. Running rich (to a point) often gains more power, and has the added advantage of providing a cooler combustion event. It also won't damage the engine, because worst-case scenario you put waaay too much fuel in the mixture and the engine stalls out. This is what your ECU does when it gets a faulty reading from the exhaust gas O2 sensor, which it uses to determine which side of the ideal ratio the engine is running on (and from there, how to adjust it towards ideal).
Running lean offers hotter, more efficient combustion. It's also a sure-fire way to start melting pistons and valves, so if you have to choose one way to mis-tune your carburetor, err on the side of having a rich mixture.
Anyways, due to the minimum a mount of air an engine can suck in at idle (when it's barely producing enough energy to overcome parasitic loss), there's also a minimum amount of fuel that can be introduced to that air charge, which all correlates to a minimum amount of energy you can deliver without damaging the engine.
Some companies (notably, one of the snowmobile manufacturers we work with) actually *do* run an ultra-lean mixture at idle; they can get away with this because they are using a very high-pressure fuel injection system on a two-stroke motor, so the fuel is mixed with oil and doesn't burn as hot in the first place. Further, the injector literally squirts fuel right onto the spark gap, so no critical engine components are damaged during ignition. Note that they only do this at idle.
Diesels do not have this issue, because they don't have a throttle valve. They always operate at 100% volumetric efficiency, and the power is varied by increasing or reducing the amount of fuel introduced to each cylinder for its power stroke. This is why a stock diesel engine (normal compression ratio) uses barely any fuel at idle. | 84 |
ELI5: Why doesn't chicken, beef, or any other processed meat go through rigor mortis when being prepared at a factory or even in the days afterwards? | Is there some kind of chemical applied or process introduced that keeps this from happening? | 52 | Hate to break it to you, but they do.
Rigor mortis, depending on conditions (animal health, size, temperature, etc) takes 2-24 hours typically. In processed meat, it's already in a package by then. Sometimes, the process is allowed to complete, as it can actually result in more tender meat.
When it comes to big animals, like cows, controlled temperature and electrical stimulation (contracting/relaxing the muscles so they don't lock up) can be used to avoid or control it. | 37 |
ELI5: Why aren't turboramjets (like those in the SR-71) used for other aircraft? | I understand the SR-71 had to deal with a lot of issues in order to keep its speed (special fuel which leaked on the runway, titanium fuselage and probably other stuff). But wouldn't the same type of engine be able to power a relatively slower fighter jet capable of easily cruise at match 2-2.5, so it doesn't have to deal with so much friction as the SR-71 at match 3.
But while the engines exist since the 1960s, relatively few fighters go faster than match 2 and it took all the way to the 21st century to have fighters capable of supercruise (and still below match 2). So I guess there has to be a reason for that. | 563 | Turboramjets are substantially larger and heavier than a standalone turbofan engine. You basically have to build two separate engines, then stick the turbojet inside of the ramjet. That also leads to the engine being much more expensive and difficult to maintain than a standalone turbofan.
Also, the ability to go that fast is of limited usefulness nowadays. When the SR-71 came out, networked radar didn't exist - every AA battery was a standalone station that could only coordinate with other radar sites by having the operators talk to each other over the phone. That meant that it was really only practical for a battery to fire on a target once it came within range of that battery's own radar, which is limited to 35ish miles, depending on how high the plane is.
The missiles themselves were also pretty dumb and would basically just try to stay centered on their current target. For a high flying, fast target, that meant that the missile was constantly turning and bleeding off speed.
The theory behind the SR-71 was that the SR-71 was flying so high and so fast that a missile fired from 35 miles away didn't have the time or speed to reach the SR-71's altitude and then catch up to it.
Modern radar is networked, which means that a missile battery can fire on a target that it can't see, but which a radar hundreds of miles away can. Missiles are also a lot smarter and can target an empty area of space where they calculate they will intercept the target at some point in the future. The result of this is that speed offers no protection from SAMs anymore and flying high just exposes you to more radar.
High speed does still offer a benefit, since it allows you to get to an enemy quicker or run away from a slower enemy. But its not worth the substantial cost of the engines. To give you some context - the SR-71 cost $34 million to build, much of the cost of which was the engines, at a time when top of the line fighter jets cost ~$5 million.
That latter point is especially true if you're only looking to go Mach 2, since you can get to that speed with a much cheaper turbofan engine. The reason that most jets don't go that fast is, again, there's just very limited utility to doing so outside of the interceptor role and most fighters are now built as multirole fighters, rather than interceptors. | 752 |
ELI5: When I need to pee, and I'm standing there waiting, but nothing is coming out, what's happening in my body that's making me wait? | Shy pissers unite! | 30 | You brain is good at knowing when the appropriate time to "go" is, so much so that it lets you be largely in charge of it. This happens because of 4 different types of nerves controlling the urinary mechanisms: Sensory (afferent) nerves, which tell you your bladder is full; sympathetic ("fight/flight") nerves which relax the bladder and keep the urinary sphincter tight; parasympathetic ("rest/digest") nerves which contract the bladder and relax said sphincter; and somatic nerves (that act on skeletal muscles, i.e. Muscles you can control voluntarily) which let you initiate when to go. When you are in line at Fatty's Pizza Shack, for instance, your sympathetic nervous system (fight/flight) is keeping that bladder sphincter tightly closed (it does this without you even knowing it, much like you don't need to consciously make your heart beat). Later, after drinking your extra large Floaty Shake, your bladder fills with urine, and sensory nerves alert you to this fact via stretch receptors on the bladder itself. As your bladder fills with more urine, the stretch sensors cause little contractions in the bladder which you feel as urges. When you finally feel like it's a good time to pee on something, your somatic nerves signal your accessory muscles (abdominals) to assist with voiding (a fancy word for micturition which is an even fancier word for urination), and your parasympathetic nerves (rest/digest) takes the hint and squeezes the bladder and relaxes your urinary sphincter. The result is pee happening. Several regions in the brain are also involved, mainly keeping you from peeing when you don't want to pee. You can consciously keep from wetting yourself for quite a while, unless you have some sort of disease where nerves are damaged or the muscles in your bladder (detrusor muscle and sphincters) don't cooperate. Incontinence = can't hold it in. Enuresis = bedwetting. | 18 |
CMV: Women in the military should have to shave their heads, or men should be allowed to grow out their hair. | I decided on this issue after reading a recent story about black women in the military saying that their hair is incompatible with hair regulations.
With the recent push to make women serve equally in the military, I believe it only makes sense that they be subject to the same hair standards as men. Consider this:
1. Long hair is a liability, in which case nobody should have it.
2. Long hair is not a liability, in which case men should be allowed to have hair at least as long as women.
I am open to changing hair regulations based on the combat role, but the regulations must be applied equally to all people in that role.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than just downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | 200 | Combat doesn't mean dick. The grooming standards are for a professional appearance. We're told that we have to be clean shaven in order for our gas masks to work, yet SF guys, the guys who have the highest chance of actually USING a gas mask, are allowed to grow beards.
The rules are there because long hair looks professional on women and not on men. The reg still says a female's hair can't interfere with headgear (helmets, caps, etc), so its fine as long as its not interfering with something that actually matters.
Cornrows look unprofessional as fuck, regardless of skin color. | 89 |
[Cyberpunk Genre] Are there Independent Shareholders or Holding Companies that hold ownership in rival Megacorps? | In some of the more hardcore settings, Megacorporations are all encompassing entities with fingers in every pie that compete against each other to the point of almost open warfare and its employees with the most stake in their companies treat their Corp as its lifeblood. Does that leave any room for people to be able to buy Shares in competing firms without being bought out or killed?
Like say you're an employee of Megacorp A, and Megacorp A has a hundred companies and subsidiaries you can invest in under its umbrella, but you think Megacorp B has a hot streak coming and you want to invest there. Is there any room for outsiders to invest like that, or would Megacorps consider such an action as akin to treason and fire you/kill you? How about if you're like an outsider not affiliated with the Megacorps? | 34 | The upper level, uber-wealthy leaders of the megacorps would absolutely invest in each other's ventures if it even hints at increasing their wealth. Even if they publicly decry everything the rival corp stands for and engage in actual turf wars via mercenaries and street thugs. That kind of corruption is the absolute least they do on any average day.
Average corpo drones are likely discouraged from placing their money anywhere near a rival corp's business. Not only would their big financial transactions be monitored to ensure they don't cross-invest, but they might even be dissuaded from going to a restaurant or grocery store owned by a rival. Anything to keep the money flowing to THEIR pockets and not the other guy's.
Outsiders who are not on any corp's paycheck are free to invest however they like. Especially if they have enough capital to help fund some of the bigger projects and riskier ventures. It's possible this sort of individual might be courted by representatives from both organizations, trying to pull them completely over to one side through invitations to exclusive clubs, lavish gifts, and all-expenses-paid vacations anywhere in the world. An average joe who tosses a handful of dollars into one corp's venture and another corp's cryptocurrency would be ignored. | 12 |
Mitosis: Which is the Original? | When a cell divides by mitosis, could it be said that either of the two daughter cells produced is the 'original' cell? Or would it be better to say that the original cell no longer exists and has been replaced by two brand new cells?
I understand this may be more a chicken-and-egg style philosophical question, but I was curious if there are any biological markers distinguishing one daughter cell from the other that could be used to declare one as being 'the original' and one as 'the clone'. | 954 | When there was still active discussion about DNA replication, there was a famous experiment (the Meselson-Stahl experiment) where cells were grown in media that only contained the N15 isotope of nitrogen. This meant all the nitrogen in the DNA was N15 instead of the more common N14.
Then the cells were put in regular N14 media so that all the new DNA strands would have a different mass than the old ones. They used this difference in masses to measure how much dna was old versus new. What they found was what we have come to know about DNA replication--that each cell gets half of the original DNA.
There's still plenty of research in the "symmetry" of mitosis, however. Turns out proteins and organelles in the cell don't always split 50-50 into the new cells, and this can change the fate of the daughter cells. We use similar tricks to measure how proteins segregate, although it's more common to use fluorophore labeling instead of isotope labeling these days.
In the case of stem cells, the daughter most similar to the parent cell may keep more of its chromatin-related proteins than the other, as one example, and this means it will have different gene regulation than its sister cell. | 480 |
ELI5: What is the difference between the roles of a Director, Producer, and Studio, in the making of a movie? | 283 | Director makes the artistic decisions; who plays who, how shots get taken, what the edit looks like.
Producers do the heavy lifting on the organisational side; contracts, locations, etc
Studios put up the money. Producers may well be involved in negotiating other income streams as well. | 144 |
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[Avatar: The Last Airbender] What's up with those animal names? | I mean, there are all these hybridized names, but we never see any normal names. I mean, we hear of koala sheep, but not koalas or sheep, for instance. No ostriches or horses, but they do have ostrich horses. | 23 | (I think the 4th wall reason is that the mixed animals are a joke about how, in Chinese, many animal names combine the characters for two other animals. For example, pandas are "cat bears". But, trying to answer in-universe:)
This is a translation issue.
In the Avatar universe, the language is much like Chinese, and many names for things are compounds of two simpler words.
Now, no one is really calling a polar bear dog "polar bear" + "dog", since if either of those two animals exist, they are very rare and most people would never have heard of them. But, the polar bear dogs have two obvious traits: that they are large polar hunters, and that they are loyal pets. There's a word to describe the large polar hunter aspect (which is shared with the names of a few other animals that we'd say are half polar bear) and a word for the doglike aspect, and the name is naturally a compound of those two.
Why are there so many animals with two aspects? This is a cosmological fact of the Avatar universe, that all creature have a dual nature. Most interestingly, of course, are humans, with a material aspect and a spiritual aspect. | 33 |
CMV: Head-first diving technique should not be taught to anyone but competitive swimmers. | It is estimated that 800 spinal injuries occur per year from diving head first into a body of water ([Link here](https://www.health.ny.gov/environmental/outdoors/camps/aquatics/minimum_water_depths_for_head_first_diving.htm)). There are a number of regulations in place to avoid diving into shallow ends of pools and lakes, but it still begs the question: Why is diving head-first taught at all? There is no apparent benefit to the average child taking swimming lessons, but the risks associated with this technique are quite high. If the technique is not taught at all, and is discouraged during training (along with reminders about jumping into ANY shallow water) people will be much less inclined to use it while casually swimming.
Edit: I underestimated how many replies there would be, and how much time it would take to get to them all. I'm done responding, as it's getting pretty late, but thank you to everyone who chimed in. Especially those of you who didn't go through and downvote all of my posts for some reason!
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | 15 | Are you sure head-first diving *is* being taught? Perhaps those 800 injuries per year all came from people who were diving head-first who had never been taught how to do so properly and safely. Perhaps a swimming class that goes over head-first diving would have *prevented* those injuries. | 24 |
ELI5: What exactly is Ebola? | 26 | Ebola is one of several viruses known as *Hemorrhagic*. Hemorrhagic is a big word that means bleeds a lot. Bleeds a *scary* lot.
The way this virus kills a body's cells is it ruptures (explodes) the cell walls. All of your cell walls begin exploding. The cells guts leak out. This effect begins in your blood and works itself deep inside. It begins affecting your organs through the blood. It spreads everywhere. Unlike some viruses that like certain areas or tissues, this stuff is nasty pervasive. It goes everywhere.
*BOOM!* Cell walls go. What this means is eventually your body can't hold all the blood anymore. Your veins and arteries, your capillaries, all of them leak. Your organs leak. Everything's leaking.
This effect begins to be noticeable within days of infection. Along with the high fever and cough, deep bruising begins to appear as the body starts leaking blood into surrounding tissues.
Ends with people bleeding from eyes, nose, mouth. Everywhere there's an opening a person will bleed from it.
That's one of the scariest parts of the virus. The bleeding everywhere. Scary stuff.
Hope that helped some. | 32 |
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ELI5: Why do people get so hungry they feel like they're gonna throw up? | Basically what the title says. I'm just lying in bed trying to sleep and I haven't eaten in hours. My stomach is grumbling, but yet I also feel sorta pukey. Why does this happen? | 26 | Someone commented but they may be shadowbanned, just letting them know.
So what a hungry person is feeling is the stomach acid acting on nothing, as your stomach is basically digesting acids. The nausea is caused by your body trying to get rid of the excess acid in the stomach. | 13 |
[Star Trek] What is the effective range of a phasor? | 25 | Yay for Starfleet Technical Manuals.
On the type 1 phaser they were: stun - thirty meters, heat - two meters, disrupt - twenty meters, dematerialization - ten meters. On the type 2 phaser the ranges were: stun - ninety meters, heat - six meters, disrupt - sixty meters, dematerialization - thirty meters. Setting dials on the hand phasers indicated nine settings on the type 1 phaser and fifteen on the type 2 phaser, of which all above ten were labeled by the letters A through E. The letters might be a reference to the disruptor-B setting mentioned in "Obsession", which would make it setting 10B. According to Mr. Scott's Guide to the Enterprise, the hand phasers used during the first four movies had only three preset levels: stun, disrupt, and dematerialize. | 20 |
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ELI5: how come if your left nose is plugged and you turn to lay on your right side your left nose unplugs? (and vice versa) | Edit: y’all, didn’t you know we have two noses and one nostril sheesh 🤧 | 1,226 | Your nose has a rhythm where it engorges one side with blood, restricting airflow, while the other breathes clearly. If everything is going well, it switches back and forth over time without you noticing.
But, if something aggravates your nasal passages (say, a cold or allergies) then there will inflammation and one or both nasal passages will become extra engorged and you will notice that one passage is more blocked than usual.
When you lay down on one side, gravity pulls the blood to the down side, so the upper passage feels clear while the lower feels blocked from engorgement. | 798 |
[Game of Thrones] How did Robert Baratheon survive as king for so many years before the start of the series, only to die in such a stupid way shortly thereafter? | Given the very short general life-expectancy of Westeros' monarchs as demonstrated by Robert's successors, and the general characterization that Robert was supposed to be an idiotic and terrible king, how did he manage not to get killed sooner? Did he have to deal with any other major conflicts during his reign subsequent to his war against the Targaryens and prior to the present-day beginning of the series? | 83 | Robert was far from idiotic, Robert was actually pretty sharp and knew how the world truly was instead of seeing it as white and black as most people do. The only reason he was a bad king because he was a fighter not a diplomat, Robert was born to live on the battle field not sitting on a throne hence why he took to drinking. He told Ned that if Joffery wasn't such a cunt(not his exact words) with Cercei whispering in his ear, he would gave up the throne years ago to go live as a sellsword in the free cities but could not doom the country to that fate.
Also who would have killed him? The North was the most loyal with the Vale not too far behind, the Riverlands where tied by marriage to the North and Vale so no hostilities there, the Westerlands where wedded to the crown through Cercei, and the Reach suffered no real losses during the rebellion and basically just sat out the entire war with no reason to hate Robert, plus Mace's favorite son was best friends with Robert's younger brother who was also the Lord of the Stormlands. Dorne is the only Kingdom who has real cause to hate Robert, but they know Robert did not give the orders and they focus their hate at Tywin and the Lannisters.
Only the Greyjoys challenged Robert rule with their rebellion which took place 5 years after Robert took the throne so he was still in his prime and had yet to fall into his cups and grow fat. | 156 |
ELI5: Why can't we use stainless steel flask to store whiskey for longer than few days? | It contains a lot of alcohol like 40%+ so any bacteria shouldn't grow inside. Can it poison you or kill you or does it only affect taste or something? | 22 | Alcohol is fermented in stainless steel barrels, so this is a good example of irrational herd behavior.
Most humans act by copying other humans that have been successful at something. When humans copy something they rarely understand *why* they're doing it, they just understand that it "needs" to be done. What this means is that sometimes they copy things that don't actually have any meaning and don't actually have to be done. A good example of this is the "this movie does not depict any real people" disclaimer that you see at the end of the movies.
That disclaimer does literally nothing. It came into existence as a result of a poorly worded legal opinion out of a California court 100 years ago. Essentially, some studio executives who didn't understand the opinion started putting that disclaimer in the credits to their movies and everyone has just copied it since.
This copying of the disclaimer is so prevalent that its extremely common to see it pop up in foreign media that will never be shown in the US. For example - just about every German TV show contains this disclaimer in their credits even though there's never been anything in Germany related to it. The reason its there is because German TV producers learned how to make TV shows by copying American TV shows and since that disclaimer was in all of the American TV shows it ended up getting copied as well.
So why do those flasks say not to store alcohol in them? Because at some point some manufacturer put that warning on a flask. Other manufacturers then saw the warning and copied it because they assumed that it was there for some purpose. And now you have a bunch of people trying to back rationalize why this warning is on every alcohol flask. This is a relatively recent thing and is mostly likely the result of a large Chinese manufacturer who saw warning labels on other US products and didn't understand why they were there.
But there is no reason for the warning. If alcohol was going to cause some reaction with the flask then it wouldn't matter how long you stored it in there - the flask wouldn't be safe for you to drink out of at all.
And again, the fact is that alcohol is fermented in stainless steel barrels. There is nothing special about those barrels. If those barrels are safe to store alcohol in then so is your flask. | 79 |
Can someone explain to me how a computer processor works....like i'm five? [ELI5] | I have never really understood this device that I use on a daily basis. I know it is very complicated and I am not asking how does it pull up this program or this program...I am more interested in the 0's and 1's and the electricity running through it and how it makes its most basic function happen which is turning a 0 to a 1? I just don't know. | 45 | Logic gates are the main tool used for dealing with binary, there's a handful of them:
* Not gates, which take in a 0 or 1 and output the opposite
* And gates, which take in 2 numbers, and output 1 if the inputs are both 1, other wise it outputs 0
* Or gates, which take in 2 number and output 1 if either of the inputs are 1, if they are both 0 it outputs 0
They work because of transistors, which you can think of as little door ways that can be opened or closed.
**Example: **
Say you're running down a hotel hall way as fast as you can (cause you're five), and the hall way forks off to a side. If you go straight there's a door ad the end of the hall way. If you're wanting to run as fast as you can and if the door at the end is open you'll take the door way (cause you can run faster straight than turning.) But if the door is closed you can't go that way, so you have to take the turn and go down the side hall way. That's like how a not-gate works. Call the door being closed 1, and open 0. Then your output is "Did he go straight?"
The other gates work the same way, but with a different hallway setup. | 21 |
[MCU] So far we have only really seen the Mind Stone and the Power Stone used to grant or enable individuals to have access to super-powers. Would any of the remaining Stones be capable of similar feats and if so what potential powers might be manifested by them? | With my question I'm not counting individuals who gain temporary abilities by using a Stone directly such as Malekith, Thanos or Doctor Strange, but rather individuals who are permanently changed after an encounter with a Stone or it's energies such that they continue to exhibit unique powers even afterwards? | 137 | It's the Space Stone, rather than the Power stone we see give anyone powers (Captain Marvel).
It's not really clear how that works, anyway. For Wanda, the Mind Stone only unlocked and enhanced existing powers. That makes sense if you think of her being limited by her own mind.
But the Mind Stone giving Quicksilver super speed? Or the Space Stone giving Captain Marvel generic powers?
There doesn't seem to be a rhyme or reason to how stones grant powers and what kinds they can grant.
There doesn't seem to be anything special about the Mind/Space stones that wound suggest that *only* they can grant powers, so it's probably safe to assume that any of the stones could grant powers, and the powers granted are not necessarily related to the powers of the stone itself. | 106 |
CMV: If a girl hates gender roles and wants everything to be equal between men and women, she can't complain when I leave the seat up | I'm not saying I wouldn't respect someone's "put the goddamn seat down" rule, but if I have to lift the lid up when I pee, girls should have to touch and move the seat just as much as I do. The inconvenience (if it really can even be considered as an inconvenience) should be equal.
I hold this belief because every time I am over at any house where there are one or more females there, it seems to be a huge fucking problem if I leave the toilet seat up instead of putting it back down into a closed or pooping position.
I don't understand how this is such a huge deal because first of all, it's much easier to put the seat back down than it is to lift it up (which I had to do). Secondly, its just a goddamn toilet seat and its not that gross (just wash your hands). My third point is this. If I had to pick the seat up and put it in that position so I could use the toilet, its only equal that girls should have to put it back down so they can pee.
Incidentally, the same girls who freak out about the toilet seat are very firm believers in how gender roles are stupid and everything between men and women should be made equal. Except when it comes to the toilet seat, because when a lesson in actual equality is looking then right in the face, THEY DONT FUCKING LIKE IT. Men are just disgusting pigs and we will never learn how to please our ladies, all fedora tipping aside.
If you can tell, I am a little steamed up by this. I know this board is not really meant for my post, but can someone try to explain to me where the hell these girls are coming from and otherwise prove me wrong
Sincerely,
The Seat Leaver Upper | 46 | Why don't you just both put down the full lid? It looks much cleaner and nicer. You also both have something you have to lift up/put down then, too.
I think most women don't like when men leave the seat up because it looks trashy, to be honest...
Also, this seems like a pretty small equality issue compared to others. It's more of a "household cleanliness and habits" standard than a gender one. It just happen to disproportionately affect men since they're the ones who stand up. Kind of like how issues related to periods or something affect women since they're the ones who get those. | 62 |
Do we live in a time of low wages, or high asset prices? | We might be living in both but I am not an economist, so don’t I have the answers which is why I’m asking others who are more intelligent. So do we live in a time of low wages, or just over inflated asset prices?
In a lot of countries workers are striking, there is a rise in antiwork sentiment, working people who are homeless, adults living with parents etc.
They’re complex issues and there is no simple solution to each of these but I can’t help but feel that much of their discontent is *actually* due to high rent and mortgage costs which has a knock on effect on almost everything. So instead of increasing everyone’s wages, **would it not make more sense to decrease asset prices, so that they are in line with the majority’s wages?**
So maybe high asset prices good for an economy, but if wages do not keep up, they become a burden on it.
I am based in the UK for context. | 32 | The economy isn't a video game where you can dial some knob somewhere to turn wages up or turn prices down. Prices are being set by millions of people buying and selling goods and services, each individually making their own decisions about how much to sell something for and how much they're willing to pay for something.
Laws that force certain goods and services to be sold for a certain price are generally considered to do more harm than good, and this has just a tremendous amount of evidence supporting it, going back to Diocletian, the Roman Emperor in the late 200s. In something like 500 BC the Roman Republic tried price caps and it didn't work back then either.
You'll hear people say that wages are "sticky" which means they increase more slowly than inflation, when inflation is high. But that's going to put financial pressure on people so it's pretty natural they'd demand raises to keep up with prices. | 21 |
ELI5: trying to find a simple answer the birthday paradox and how having 23 people in a room means a 50% chance of two people sharing a birthday. | 89 | "share a birthday" is not a property that a person has, it's a property that a pair of people have. With 23 people in a room there are 253 pairs of people (maths calls this 23 choose 2). There's only 366 days that could be shared by each of those pairs, so it's quite unlikely that they're all distinct.
Those pairs of people aren't quite independent, so it's not so straight forward as to say there's a 253/366 chance of a shared birthday, but that view should make it a lot more intuitive that these are comparable numbers and a 50% chance is not insanity. | 143 |
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For light to qualify as a laser does it have to be emitted in a beam or does it just have to be of one wavelength? | If it does have to be a beam, what is the maximum spread it can have and still qualify? | 2,775 | Laser has nothing to do with colour or beam divergence. Lasers are just good for making tight beams, and they inherently make a rather monochromatic source. You can have a really wide laser beam, and you can have a rather narrow focus with lenses or mirrors.
L.A.S.E.R. is actually an acronym. It's Light Amplification by Stimulated Emission of Radiation. To be a laser, it has to be light amplification done by stimulating the emission of radiation. Basically you energize certain types of materials so much so that more electrons are in the energetic state than the ground state, and then as light passes it causes electrons to emit basically identical photons, amplifying the light. The coherence of this light is what makes laser have a narrow wavelength band and allows for tight beams if desired.
This is opposed to spontaneous emission, which is most other sources, like an from a hot object like an incandescent bulb or fluorescence like in a fluorescent lamp or white LED. Here a minority of electrons are energized, and they randomly emit leading to a less coherent light source. Some spontaneously emitted photons may trigger stimulated emission, but it's a minority effect. Once you pass a point called population inversion (more electrons energized than not) stimulated emission takes over as a dominant effect as you can start lazing. | 1,693 |
Martha Nussbaum on the profesor of parody | Martha Nussbaum writes a criticism of Judith Butler works, and more importantly her "way" of arguing and theorizing.
> Feminist thinkers of the new symbolic type would appear to believe that the way to do feminist politics is to use words in a subversive way, in academic publications of lofty obscurity and disdainful abstractness
Is there a name or influence that we could group those types of works together? a umbrella where they more or less fit?
She claims
> These developments owe much to the recent prominence of French postmodernist thought. Many young feminists, whatever their concrete affiliations with this or that French thinker, have been influenced by the extremely French idea that the intellectual
does politics by speaking seditiously, and that this is a significant type of political action. Many have also derived from the writings of Michel Foucault ...
and cites Focault as one example. However I keep seeing here people deying that Focault was a postmodernist or that we can use the word postmodernism to describe this particular kind of work. In fact, for the way that is argued in this sub, I started thinking that the label of postmodernism had no possible application whatsoever to anyone.
Regardless if you disagree with Nussbaum she is clearly no hack or bad philosopher, so can someone tell me what characteristics shares those works that she is criticizing? what do they seem to offer that other kind of analytic and rigorous, less based on personal experiences, work lacks? | 29 | > Regardless if you disagree with Nussbaum she is clearly no hack or bad philosopher, so can someone tell me what characteristics shares those works that she is criticizing? what do they seem to offer that other kind of analytic and rigorous, less based on personal experiences, work lacks?
Both Nussbaum and the philosophers she is criticizing put a high priority on clear and precise use of language. This is fundamental of philosophy in general, so claims by Nussbaum that you cite above basically just miss the point and is a symptom of how different traditions approach clarity and precision of language.
Nussbaum comes out of a tradition of philosophy, analytic philosophy, that was born out of a movement against German Idealism of the time and put a high priority in common sense, by way of G.E. Moore, and precise language and logic, by way of Bertrand Russell. Part of this inception of analytic philosophy is in the combined work of Gottlob Frege and Bertrand Russell, which has since been called "ideal language philosophy." The goal of ideal language philosophy, as it's said, was to create a logically perfect language that was absolutely free of the ambiguities of ordinary language. While the goal of ideal language philosophy was never reached, it's influence was profound on thought in general, not just within analytic philosophy but in logic in general as well as computer science. The computer in which you are reading this is written in programming language can be traced in part to Frege's work.
In reaction to this, still within analytic philosophy, was ordinary language philosophy, which drew greater influence from G.E. Moore, and argued that philosophical problems did not arise from the lack of an logically precise ideal language but rather from misunderstanding and confusing different ways of speaking within ordinary language. Once we understand why ordinary language is used the way it is in various circumstances, then we can dissolve whatever philosophical problem that has arisen.
Both of these traditions within analytic philosophy influence the way Nussbaum approaches philosophical language, in one way precise and another common sensual.
The tradition of philosophy that she finds in Butler, and by extension Michel Foucault, is no less concerned with precision and clarity of language in philosophy. In fact the since-named "linguistic turn" in analytic philosophy in no small way also played out in so-called continental philosophy through the work of Ferdinand de Saussure, Edmund Husserl, and Martin Heidegger. However, whereas analytic philosophy approached language either by building anew from logical principles or observing how language is used in various forms of life, continental philosophical approaches viewed language as an entire system of relations which give meaning through things like binary oppositions, sign and signified, etc., by way of Saussure's structural linguistics, or by scrutinizing the historical development of language, by way of Nietzsche and Heidegger. In a sense, continental philosophy is closer to ideal language philosophy in that it more or less considers ordinary language to obscure matters but, to use the analogy, the solution is to untie or at least expose the larger Gordian knot instead of either cutting right through or letting it be within a language-game.
So Nussbaum might see a term like "human rights" and might consider it within the logical structure of the proposition it's used and/or how it's used in the context in which it is used. However, for someone like Butler or Foucault, "human rights" already entails a relation to its opposite and the overall structure of meaning that it's used within and/or its historical relations and the baggage of meaning that carries with it.
If there's any solution, it's recognizing the implicit views one has of philosophy of language, either organically or learned, and recognizing other ways of speaking clearly and precisely about philosophy. | 11 |
[Matrix] When Neo woke up, why didn't the robots kill him. | When Neo first awoke from the Matrix why didn't the robots just kill him (and all humans that woke up) before 'flushing' the pod? | 16 | Because as we learned in the third movie, the machines were allowing the humans to escape and were waiting for the appearance of The One to destroy Zion and let Neo and his chosen group start it over.
I don't know what reason the humans had established for the machines not killing them, or what the logic was before they wrote the final movies, but that's the real in-universe answer. | 30 |
ELI5: Schrodinger's Cat | 30 | Quantum mechanics can be said to describe reality, but not in the concrete terms with which you can describe the fall of an apple from a tree. Descriptions of the quantum world come in the form of probabilities.
Schrodinger's cat is an analogy which is meant to point out a basic absurdity in this idea. In his model, the cat's death relies on the subatomic: if a radioactive atom decays, the cat dies.
Since the subatomic can only be described in terms of probability, the cat can only be described as a probability. This means quantum mechanics ends up describing an impossible situation, in which the cat is equally alive and dead.
His point: "That prevents us from so naively accepting as valid a "blurred model" for representing reality." Pretty straight forward, after all. | 19 |
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[Harry Potter] What does "Abracadabra" do? | 56 | Fun Fact. In the wizard Community, "Abra Kadabra" is the linguistic equivalent for "Duh" in Muggle culture, as something you would say when someone else said something incredibly stupid.
A number of years ago, some young Wizards used their magic to perform what would look like Ordinary Magic tricks to Muggles, presumably for quick cash. And as a joke, they used words like "Hocus Pocus" and "Abra Kadabra" in place of regular incantation. The phrase stuck around, and that is why Wizards can't bring their younger children to Magic acts in Vegas, otherwise they would burst out into giggles whenever the "magician" would perform a trick. | 61 |
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