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ELI5: Would dyslexic people be okay with languages that aren't letter based such as Chinese? Is that how dyslexia works? | Dyslexia has several different symptoms, such as orthographical awareness deficiencies, naming speed, motor programming, or even phonological awareness deficiencies. Someone who suffers phonological awareness deficiency might have trouble with latin based alphabets, but not Chinese alphabets. Someone with orthographic awareness deficiency might suffer in Chinese alphabets, but not latin or cyrillic.
It just depends on the kind of dyslexia that they have. | 327 | 857 |
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why are philosophical texts not written in simpler terms? | Most professors advocate for students to write in simpler and comprehendible words, yet philosophical texts feel impossible to read. Is there a deliberate reason for this, or has it always been this way? | If you read any article in an economics journal like QJE and compare it with an undergrad paper, you'll see totally different levels of difficulty. Its hard to parse QJE papers without an understanding of a lot of math, but for a lot of undergrad papers, sure.
​
Its the same for philosophy. Rigour is expected to be much higher in academic philosophy as opposed to undergrad philosophy, and as a result papers and books are much more technical. | 99 | 96 |
ELI5: What do computer scientists research in academia, as opposed to industry? | So I was just wondering this today after listening to a seminar from of my CS professor's about his AI research. The talk was fascinating and intelligent, but it also seemed like something that could easily be developed by a tech company for profit. Most professors of any type have a Ph.D. and they typically have teaching responsibilities, but how does their research differ from say, some of the AI research and development coming from Google? | Most university researchers have research budgets because they wrote a research grant proposal to study something. They have papers to publish, and their research gives them things to write about, and their students topics to study.
Most corporate research depends on the company's products. Product A needs feature B so there's someone doing research on "can AI do B?"
Academic research is "B might be possible with AI". | 17 | 26 |
What are the differences between a REST api and other APIs? | if a mobile application communicates with a web application is it called a restful api? When is json not needed in rest? | REST a information transfer standard. It is an agreed upon contract on how to read and write information over the web. There are other standards such as SOAP and GraphQL. It may use other data formats but JSON is the most common.
JSON is data format. JSON is in the same category as CSV, YAML, TOML, XML. These are all data formats.
Think of JSON as the equivalent of the conventions when writing a physical letter, how you include your name and address and the recipients name and address before the message body, then think REST as the postal system that you have to adhere to in order to have your letter delivered. | 38 | 48 |
ELI5:Plea deals in the US - why are they used so much and how do they work? | I'm almost done with law school, but in Europe. In my country, there are actually pretty strict rules for someone to just confess to a crime and the judge ruling it as a confession. This is because it could be a false confessions etc.
But my impression is that in the US, plea deals are widely used. I've heard some stories where innocent people have taken plea deals, because they are afraid of a long sentence and would not like to risk it.
Does guilty beyond a reasonable doubt not work as intented in your country? | Trials cost money, both for the accused and for the people who are represented by the prosecution. Meanwhile juries can be fickle creatures, and you really cannot count on them to reach the right conclusion (look at OJ Simpson, 99.9999% chance he did it, but walked away with an innocent verdict).
Better to skip the expense of a trial, secure a guilty verdict, and enforce even a fraction of the prescribed punishment, then to waste a fortune and risk that the perpetrator walks.
It's a fucked up a system, but that's how it works. To paint it simpler terms, better to be guaranteed that your boss thinks that you're a good employee, than to risk a 50/50 "you're great" vs. "you suck".
Source: Life long American, degree in Criminal Justice | 19 | 31 |
Does an insect's exoskeleton heal from injury? | Does an insect's exoskeleton heal from injury? | It depends on at what point the insect is in its life cycle. They do have clotting mechanisms that will block an external injury and keep them from desiccating, in most cases. If it's an adult insect, that may be as far as external "healing" goes. If the insect is a juvenile and pupates or moults after the injury, the exoskeleton will typically be completely reformed or replaced. | 657 | 1,553 |
ELI5:Why are universities such as Harvard and Oxford so prestigious, yet most Asian countries value education far higher than most western countries? Shouldn't the Asian Universities be more prestigious? | In most Asian countries, they take education super seriously, like people rent out rooms just so they can study more. I'd only assume that they universities are very selective of their students and that the criteria to get in would be equally as selective. But, when looking at the top universities in the world, it seems to indicate that the western universities are better. And also, universities such as Harvard, Oxford and the like seem to be the best universities in the world. | Oxford and Harvard typically place well in any inter-university student competitions that they enter and produce world class research. That's 100's of years of being 1st, 2nd or 3rd so they built up reputations. Consequently they have the most competitive entry requirements now because demand is so high which in turn makes them more prestigious. In turn they get the best students and continue to excel in research and competition. | 3,717 | 3,798 |
ELI5: how do we know how well other animals can see or smell? | Two main ways:
1. Dissecting animals sensory organs to analyze their structure (For example, we can look at the structure of rods and cones in their eyes and theorize based on that).
2. Running tests like playing high or low pitched sounds, putting them in mazes with food, etc. | 87 | 234 |
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[Pokemon] Why are all gym members blind to the type strength matrix, and pointlessly specialize their teams? | In league competition, the gym challenge is a time-honored tradition of recognising excellence in trainers. Specialised gym types are designed to be a test of type-specific knowledge and skill. To face a league-sanctioned Gym Leader and conquer them is to demonstrate mastery of their type. Secondarily, specialised gym types help to promote a more controlled environment where pokemon are at less pronounced risk in combat. For a gym leader who can participate in as many as six battles a day, facing a trainer who knows what to expect can have a huge impact on the well-being of their pokemon.
Pokemon gyms also serve a secondary purpose in their communities. Trainers will often seek out gyms as places to study the subtleties of specific types under the care and observance of the gym leader. Through this course of study a trainer can receive a "non-combat attained" badge which are recognised under the League's "Professor" and "Ranger" programs, but do not grant access into high-end competition ladders.
Studying in a gym also offers some trainers an alternative way to attain normal "combat demonstrated" badges. By actively participating in combat drills with those who challenge the gym, those who are less confident in pokemon battles can build up experience and mastery over a type that way.
Thank-you for your query on "Specialised Gym Types". Would you like to load "BILL'S PC", submit a "POKECENTRE TICKET" or "LOG OFF"?
>_ | 79 | 37 |
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ELI5 : Ayn Rand and objectivism | 1. Reality exists as an objective absolute—facts are facts, independent of man's feelings, wishes, hopes or fears.
2. Reason (the faculty which identifies and integrates the material provided by man's senses) is man's only means of perceiving reality, his only source of knowledge, his only guide to action, and his basic means of survival.
3. Man—every man—is an end in himself, not the means to the ends of others. He must exist for his own sake, neither sacrificing himself to others nor sacrificing others to himself. The pursuit of his own rational self-interest and of his own happiness is the highest moral purpose of his life.
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ELI5: Why do American semi-trucks (18 wheelers etc) exclusively use inline 6-cylinder engines, no matter if it’s a Mack, Detroit Diesel, Cummins, or Volvo-built engine? | I get why they are diesel, but why are they all of the inline 6-cylinder configuration? Why not V6 or straight 8 or freakin huge inline 4-cylinders? | Inline-6 cylinder engines have a unique characteristic: they can have perfect primary and secondary dynamic balance without needing a balance shaft.
Essentially what this means is that the forces on the engine caused by the pistons and whatnot moving around mostly cancel each other out, and the engine runs very smoothly without needing extra, very heavy parts to dampen the vibrations.
All other engine types (V8, V6, especially I4) have imperfect balance, and V6 and I4 engines have bad enough balance that they need the heavy balance shafts to reduce vibration. I6 engines (and engines made of I6s like V12s) don't.
As the mass of the moving parts increases, the forces involved increase, so by the time you get to the size of engine needed to move an 18 wheeler, you're dealing with some truly massive forces. With anything other than an I6, this would mean monstrous vibration or a stupidly heavy balance shaft that would take a lot of engine power to spin.
Thus, for large engine applications, I6s and V12s are an easy choice. | 2,159 | 1,098 |
If I get a TT offer, what things should I negotiate in the contract. | I think everyone knows that salary is negotiable, but I am aware of people that have asked for other things before accepting (or declining) a position.
Are there some basic things that I should be sure to ask for that most new hires would overlook? | The big one is obviously salary, but many times department heads are very constrained in what they can offer. If the faculty is unionized, there may be strong restrictions in what new faculty can get. But there are other things that are much easier to negotiate. The big one is the startup package: research money, computers, lab facilities, funding for grad students and post-docs. You can also negotiate your teaching load for the next few years and possibly even administrative load. Don't forget to get your moving costs covered and hopefully even housing support if the university is in a tough housing market. And obviously if you've got a two-body issue, this is the only time you'll actually have leverage so is it while you can. | 17 | 18 |
ELI5: Why are humans the only animals with brains as advanced as our own? | like, if having a bigger brain to use for problem solving, reason, etc. isn't necessarily a biological disadvantage, then why aren't there like a races of monkey people (us), tiger people, wolf people, etc.? | Being smart is certainly an evolutionary advantage, but it comes at a cost. For example, for humans to walk on two legs and thus have hands free to use tools etc, and also to have huge brains, it makes human childbirth much more of an ordeal than any other animal, and it also means newborn humans are much more helpless than those of many other species.
So it's not that being smart isn't an advantage, it's just not the most economical advantage possible for most species. With tigers, some may be smarter than others, but some also run faster or have bigger teeth, and those traits turned out to be more useful than the bigger brains.
The thing about evolution is, it finds *local maxima*. Yes, humans are better adapted than tigers, as evidenced by the fact that we use them for rugs and not vice versa. But that doesn't mean that if you make a tiger slightly more like a human it will be a better tiger. | 27 | 21 |
ELI5: Why are some medications race-based? | There's sufficient genetic difference between various human races to create different reactions to certain drugs, or increase the possibility of certain reactions in certain races.
An example of one such difference is a genetic switch in some Asians that floors them completely when they have one drink because their metabolism very rapidly turns the alcohol they ingest into acetaldehyde, which is poisonous when in larger doses and gives them wicked hangovers.
Some drugs are metabolized or take effect in different ways as programmed by race-specific genetics, and that can lead to bad side-effects such as cancer or a drug that just doesn't work at all. | 31 | 42 |
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Why is glass not crystalline? | My understanding of glass was that it was that its a noncrystaline solid. Which right off the bat is confusing because theres something called "crystal glass".
But in addition, I was looking at [wikipedia](&) about glass ceramics, which have both crystal and crystal aspects. In particular:
>Glass-ceramics are mostly produced in two steps: First, a glass is formed by a glass-manufacturing process. The glass is cooled down and is then reheated in a second step. In this heat treatment the glass partly crystallizes. In most cases nucleation agents are added to the base composition of the glass-ceramic. These nucleation agents aid and control the crystallization process. Because there is usually no pressing and sintering, glass-ceramics have, unlike sintered ceramics, no pores.
So it sounds like if you melt down a bunch of stuff and mix it together, it will cool down and become glass. But then they heat it up again and cool it down again, and it becomes crystal. I dont get how that works. They mention "nucleation agents", but also say "in most cases", implying its not always required.
What exactly is a glass and what causes it to be that way? | Glass is by definition a non-crystalline solid, meaning it is made up of molecules that have no long range order.
Glass can be made up of lots of different materials, silicon oxides are really common example. SiO2 can be crystalline (mineral quartz) or amorphous (fused quartz). The same is true for lots of materials we use in different glasses, they can have both crystalline and amorphous structures depending how we construct them.
For example, if you melt down silica into a molten state, and cool it down very quickly, the molecules will be frozen in place in an amorphous state. If you cool it down very very slowly, with the introduction of a seed crystal or a nucleation site, the molecules will move into an ordered crystalline state before they solidify.
In the text you quote they are producing a semicrystalline state, that consists of small ordered regions surrounded by amorphous glass, as a means to get rid of the pores that are often present in some crystals.
Finally, you mentioned crystal glass. That's actually a misnomer, it's just a common name for a certain type of lead based glass. | 19 | 18 |
ELI5: How do scientists determine the possible habitability of exoplanets? | With the search for possible Earth analogs in our universe going on still, how to scientists determine whether or not a planet is habitable even tho often times they can't physically see the planet? | They can tell how bright the star is fairly easily. From this information they can determine how much energy the star is putting out. Then, they look at how fast the planet is orbiting around its star by measuring how often the planet causes the star's light to dim or wobble. From information about how fast the planet is orbiting they can determine how close it is to its host star.
Now that they have the energy output of the star they can determine if the planet is in the range where water can be liquid. If the planet is too close then all water will evaporate but if it's too far then the water will all freeze. | 12 | 16 |
Why does the Collatz Conjecture (and problems like it) matter? | I was watching a video from one of the 3628468 youtube channels that the bearded englishman has and it mentioned this problem and I started to think, why does such a thing matter? Seems like just a funny maths thing for a child to play with but in the video the host mentioned that people have "ruined" their careers trying to solve the problem.
What would happen if the problem was proved false/true? Is this a check on if maths as a whole work or something?
If there is a simple and obvious answer, I do apologize. I'm just a lowly car mechanic and a bass player on top of that. | The problem is hard because it digs into how multiplication and addition interact with each other. We have lots of number theory that focuses on multiplication - this is where a lot of the importance of primes comes from and there are lots of methods that help us solve equations - and we have slightly less number theory that explores how numbers add together. It's not that addition doesn't happen in multiplicative number theory, or that multiplication doesn't happen in additive number theory, it's just that the kinds of questions you ask and methods you use are unique to each type.
There are a few questions that cross the boundary, however. For instance, Goldbach's Conjecture says that every even number can be written as a sum of two primes. Primes are necessarily multiplicative, but asking what numbers you get from sums is additive and so this question crosses the boundary and is therefore very hard. The ABC-Conjecture is another such question that remains unsolved (despite insistence by some otherwise), and it basically asks how information about primes persist through addition; if A+B=C, then how do the prime properties of A and B determine (or not) the prime properties of C?
Collatz Conjecture is another in this family. It mixes properties of 2,3 and addition in this dynamic kind of thing. Plus, heuristically, adding one is, in ways, the most destructive to multiplicative information, so the Collatz Conjecture has a lot of difficulties to overcome. (For instance, to get brand new primes, multiply all primes that you know together, add one, and every prime that you get from this new number is a new prime. Or, there are lots of primes like 2^(p)-1 whereas 2^(p) has the highest power an integer of that size can have.)
Solving the Collatz Conjecture will not really do anything on its own. But, because it is this kind of problem that crosses the boundaries between multiplication and addition, a solution should help us navigate that realm better. As with almost all unsolved math problems, we don't really care about the actual solution or answer, what we're really interested in are the new methods that will almost surely need to be invented to solve them. We can use those methods elsewhere and to ask new questions. And that's really what matters. | 35 | 17 |
Why do most animals have their eyes, nose, and mouth clustered together in roughly the same way as other species? | Why are the eyes usually horizontally aligned, with a nose centered on the face and a mouth slightly below? What are the benefits of this over say having the eyes and the mouth on opposite ends of the body? | This doesn't answer ALL the factors you asked about but:
* you want your nose close to the mouth to smell your food (for safety reasons)
* you want your eyes as far forward and as high up as possible for seeing things
* You want your mouth far from the waste-hole
* You want all three of those sensory organs as close to the brain as possible (faster processing AND shorter wires are less likely to get injured. This latter one is actually a big deal. If your eyes were away from your brain, breaking your neck would blind you! If your mouth was away from your head, breaking your back means you physically cant eat because you can't swallow).
You're right, the typical configuration isn't the ONLY solution to the above (and other) requirements riddle, but it's a pretty darn good solution - and evolution is *very* much a fan of "if it's good enough, that's good enough". | 226 | 170 |
How can tungsten be a metal, but have *higher* electronegativity than phosphorus, which is a non-metal? | it's generally taught that metallic or non-metallic character is governed by the electronegativity of the element ([for example](http://www.meta-synthesis.com/webbook/37_ak/NT.jpg)), so what's the deal with tungsten (and the others...)?
edit: gold is an even worse offender. | I am a professor that studies the bonding in solids. The fundamental connection between EN and type of bonding is nothing more than a decent correlation. Electronegativity is a property of an element that arises from the energies associated with orbitals as they are filled or emptied. One could imagine the energy associated with filing the p- or d-orbitals as something like an upside-down parabola. This means the energy of the system, i.e., the atom, is minimum when a set of orbitals is completely filled or unfilled. Interestingly enough, a similar tend exists for the degree of bonding within a solid. Take H2 as an example for how electron filling at the aim dictates binding in a molecule - same as in a solid. Hence, the coincidental correlation. This happens all the time in atomic systems because everything is strangely similar and connected in someway. A bit more detail in the bonding, it turns out that half filled sets of orbitals on an atom leads to strong bonds when the atoms bond to each other. This is because the resultant binding orbitals are filled and the anti bonding orbitals are unfilled. As the orbitals are further filled, the strength of the binding decreases because some previously unoccupied anti bonding orbitals are now being filled. What happens in solid in this regard is highly similar to what happens in molecules. On the other side of the coin, as the orbitals of the atom are depleted lower than half filled, the resulting bonding in the solid also decreases but to a lesser extent, and can some times result in the remaining bonds becoming very strong.
So, back to the initial question, taking the binding in the d-block, we see a decent spectrum of bonding as EN changes, but the "metallic" character of the metals actually decrases as we go to the left. For example, Ti and W both form very strong bonds in their associated solids, are still metallic, but are more like covalently bonded ceramics in that they are hard, more brittle, and have decreased conductivity (a better measure for metallic character). However, in the case of Au, with its high EN and half filled s-orbital, we encounter a highly mailable, highly conductive solid. So, we can easily see that this correlation is simply just a correlation that is old, inexact in its fundamental foundation, and should be used as a simple learning tool rather than something sourced from fundamental physical phenomena.
TLDR; it is complicated and you actually have to read to understand science :) | 37 | 124 |
eli5 how does red blue and green lights in screens create a white light and all other colors? | how does this work in phones? | We know how human eyes work. They have rods and cones, and the colour sensitivity is to red, green, and blue. So we built computer screens with those colours to basically stimulate those things in your eyes exactly the way we want them. It's not perfect, but it's close enough.
If we were a different species with different eyes, screens would be built differently. Thankfully animals don't watch TV or use phones. | 29 | 18 |
ELI5: What causes revolutions? How bad do things have to get before such a large number of people agree on how bad things are and come together to fix it? | We hear politicians make promises during their campaigns, yet it seems that even though hardly any of those promises are kept, people don't really hold them accountable. However, there obviously have been times when the people get fed up enough and start a revolution. How come something like this hasn't happened to hold politicians accountable for their promises? How bad does it have to get? | One big condition is common knowledge. In many cases, each individual feels that things are rotten, but worries that they are the only ones who feel that way. It's when something big happens that makes everyone realize the majority feels things are rotten that a lot can get done. | 112 | 302 |
How do infants and toddlers who barely speak get diagnosed with eye problems, when we have no way of knowing if they're able to see things just the way they are ? | Recently saw a video where a baby got correction glasses and was able to see it's parents properly for the first time. How do parent get to know their kids have issues with seeing and even if they do, how are doctors able to correctly prescribe them glasses | Parents may include an eye examination as a routine check on an infant's health.
There are diagnostic tools that will measure the focal point of an eye's lens. Myopia, nearsightedness, is caused by the lens focusing in front of the retina. Hyperopia, farsightedness, is caused by the focus behind behind the retina. | 31 | 32 |
Why are some races of humans taller than others? | I was thinking about this today, as I sat eating lunch near a group of men who appeared to be Hispanic migrant workers. I think they were Guatemalan.
My ancestry is European, specifically northern German, and I'm 6'4" tall. But every one of those migrant workers was less than 5'5" tall.
One [source](http://www.disabled-world.com/artman/publish/height-chart.shtml) I found says that the average male height for Guatemalans is 5"2". The average height for German men is 5'10". The tallest race is from the Dinaric Alps, where the average is 6'1". Next tallest are northern European countries - Finland, Norway and Sweden.
What are the evolutionary reasons why one race is on average shorter than other races?
| While genetics certainly plays a roll, health and nutrition play an important role as well. This is evident in Korea wear young men in the north are on average significantly shorter than their counterparts in the south. This difference is not evident in older populations due to the fact that economic conditions were more similar in the past.
These changes are evident elsewhere as well. The Dutch, once shorter on average than Americans, are now the tallest people in the world, on average (not considering subpopulations). | 16 | 27 |
ELI5: Why people say "pardon my French" right before/after they swear | In the early 19th century, intellectuals and those well-traveled would often drop French words into the conversation to show how clever they were. They would then point out that the word they had just used was French, often to embarrass someone nearby who was less fluent in the language.
To counter this, the less well-traveled (often poorer) people would, after swearing, loudly proclaim, towards those that had previously used French in the conversation, "Pardon *my* French."
The latter stuck. | 4,895 | 4,030 |
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What happens after a failed suicide attempt? | What happens when someone is hospitalized after a failed suicide attempt? I've heard of "suicide watch". What exactly is it, and what goes on during it? How long does it usually last, say if someone tried to OD on pills? What happens afterwards? Outpatient care? Inpatient? How long is someone typically in the hospital after a suicide attempt, such as an overdose? Would it be different for a more violent/severe attempt?
edit: I mean in the United States, if that makes a difference.
Note: This is not a cry for help or any need to be concerned, it is curiosity. Also, I'm sorry if this is the wrong subreddit. I wasn't sure where to put this.
| Most states have laws that allow a police officer, a doctor, or a specially trained social worker or nurse to sign a form that allows someone to be held against their will for 72 hours, so that the person can be evaluated to see if they are sane enough to take care of themselves.
How it usually works in practice is this: The person commits the act, and someone calls 911. The police and paramedics show up, and take the person to the hospital. Someone along the way will sign the mental health evaluation form. If the person is really sick (from a serious OD, for example), and requires an extended hospital stay, they will be treated for the condition in the hospital as usual, they just won't be allowed to leave and they will get psychiatric care while there. If the person isn't that sick, they will be evaluated in the emergency room and transferred to a locked psychiatric facility for evaluation. If you live in a large urban area, there is also a possibility that you will be held in the ER for those 72 hours simply because there isn't anyplace else that will take you, as psychiatric wards are not money makers, so there aren't enough to meet the needs of the communities.
In theory, a psychiatrist is supposed to evaluate the person's mental health within that first 72 hours, and determine if they are a threat to themselves or others. If they are, they can hold the person until they are no longer immediately dangerous; if they are not, they release you.
Most people, even those who are seriously depressed, are so fucking sick of getting the hospital runaround by this point, that they are well past the idea that killing themselves is a good idea, so they get released once they are evaluated. | 11 | 17 |
What would be the economic consequences of making it law for enterprises to share x amount of their profits equally with workers? | Minimum wage laws are bad because they needlessly raise the value if labour above market prices and hurt profits.
Of removing minimum wage laws would increase profits, then how would Enterprises respond to a law forcing them to share, say, 50% of their profits equally among all workers?
It seems like a good compromise,because workers would only get compensated as long as the business is making a profit. | The issue with this proposal is it's very easy to change the amount of profit by reinvesting into the business, either through capital or labor. There's no guarantee that such reinvestment would benefit the lower wage workers of the business. | 15 | 17 |
eli5: Why does working out helps so much with mental health? | I have OCD and working out ALWAYS makes me feel better whenever I have spikes. How does that work? | Exercise had been shown in many studies to promote the production of serotonin and dopamine, the two neurotransmitters responsible for making you feel good. Evolution has selected for physical activity to make us feel good, making it more likely for us to be physically active, which promotes our physical health. This is called a positive feedback loop, and is an example of one of the many, many positive feedback loops employed in your biochemistry. | 1,110 | 890 |
eli5: Why are there so many bad chemicals in cigarettes? | A cigarette is basically just paper, tobacco and a filter. So how do so many harmful chemicals get in them? | While a lot of the additional chemicals are ‘naturally’ present as part of the tobacco, there are a lot of additives as well, added by tobacco companies to help the smoker better enjoy the smoking process and increase tobacco consumption.
Smoke by itself is quite harsh, and so compounds like menthol are added in varying degrees (even cigarettes not marketed as containing menthol) to numb your throat.
Bronchodilators are added to help the tobacco reach inside of your lungs better, something typically not present in cigars where the smoke is intended to stay in your mouth. | 1,353 | 1,357 |
ELI5: why are loud noises so scary to many animals and humans? | We evolved hearing to both find food and identify threats.
The worst threats are those that don't care if something else hears them - that indicates confidence which is NOT good for the animal hearing it.
This is why lions roar - to show everyone around them they're the boss. "Come get it." | 63 | 47 |
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Why does vision improve when one is squinting? | This is actually more of an optics question than a biology question. When light passes through a small hole, it becomes focused because the hole is limiting the paths that the light can take. The smaller the hole, the more focused it becomes, but the dimmer it becomes (because it's letting less light through).
When you squint, the light becomes focused by traveling through the small gap in your eyelids, and the effects of your eyes' lenses decrease.
For more information, you can look up pinhole cameras, or camera obscura. It's pretty interesting stuff. | 18 | 34 |
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ELI5: Why is Hillary Clinton using her personal email a big deal? | By law, these are considered government related business documents and must be stored and maintained on government servers for future access in case of investigation, etc. Anything that she sent from her personal account would not be stored on a government server. Additionally, sending from a personal account is just simply not as secure as sending from a White House account and is more susceptible to hackers. | 120 | 116 |
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Eli5: why does the country Liechtenstein exist? It’s an incredibly small country in Europe, why isn’t it just part of Switzerland or Austria? | Originally, there were many, many such small kingdoms in Europe, ruled by powerful local families.
The land was bought by the House of Liechtenstein, and nominally ruled by the Holy Roman Empire, but became a sovereign state in 1806, as part of a loose German confederation
During the first and second world wars, many small states were eaten up by larger ones. However, Liechtenstein never really caused any problems for other countries, and kept itself to itself, and so there were always bigger fish to fry, and it remained self sufficient. It didn't have any great wealth or natural resources.
It was just too much effort for any other country to bother annexing it. | 10,109 | 9,373 |
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ELI5: The benefit of spending millions/billions on acquiring another company, rather than starting one themselves. | I mean like Amazon buying Audible in 2008 for $300 million or Walmart buying Jet.com for over $3 billion.
Why couldn't Amazon just start their own service rather than spending money on someone elses? Walmart has $3 billion to spend, why not invest that in themselves and make their own version of Jet.com? | You get their workers, machines, software, facilities, and customers in one transaction. Sure, you could get those things separately in a thousand transactions, but that does it cost to execute those 1000 transactions? When it's cheaper, you start a new business. Plus, when you buy someone, there is not an additional competitor diluting the market niche. | 24 | 17 |
US stock market hit 30,000. I am a hairdresser. How does this help me? (I don't own stocks) | With COVID-19 raging my income has been cut in half. Can someone teach me how a soaring stock market helps? I am firmly working class/low middle class | **Direct Impacts**
The stock market itself does not necessarily have a direct impact on you. If you have retirement savings, you generally want the market to grow, but short term gains and losses don't have much on an impact.
**Indirect Impacts**
Even if you don't own stocks, the fact that others own stocks could lead to indirect benefits to you. If increases in the stock market increase the wealth of people in your area, you could potentially see increased spending where you live, which could include increased demand for your services. One concrete example: a customer of yours has an increase in wealth because of their investments, and decides to leave you a higher tip.
**It could be a good sign for you**
Even if it doesn't benefit you directly, an increase in the stock market is generally a good signal for other parts of the economy. Generally speaking, stock prices increase when people expect economic growth in the future. Much of the recent gains in stock prices is attributable to optimism about the COVID vaccine, and optimism for increased US government stability, both of which are expected to lead to more spending and more economic activity. More spending means more business for you. So, if you take movement in the stock market as a signal of what people think is going to happen in the economy, what we're seeing might be a sign that your income will increase in the future.
**It also might not be a sign**
There are plenty of reasons why it might not be a good signal for you, though. First, sometimes stock market prices go up due to speculation that they might go up in the future, rather than real evidence that the economy is going to grow. This is what's called a "bubble" - stock prices rising higher than the fundamental value of the stocks. Also, general economic growth might not mean that your specific situation will improve. The Dow Industrial Average (that's the stock that hit 30K) tracks 30 large companies traded on the US stock exchange. So increases in that really just means that investors expect those 30 companies to do well in the future. Those 30 companies are deeply integrated with much of the US economy, but in no way do they represent everyone. Some places will continue to struggle, while others continue to thrive. The stock market can't tell you much about what will happen to you, specifically. It's a sometimes-misleading gauge of what investors think the economy will do in the future. | 198 | 277 |
ELI5: P vs NP | I'm talking about this:
https://en.wikipedia.org/wiki/P_vs_NP | As you'll get older you'll see that sometimes there are problems you will need to solve. Maybe you'd like a cookie but you can't reach the cookie jar, that is a problem you can solve by taking a chair and climbing up to the cookies.
Well, P and NP are two families of problems, "P vs NP" is just asking if those two families are actually the same one.
NP is the family of problems whose solution can be verified easily. For instance the solution to your cookie problem could be easily verified by climbing up on a chair and taking a cookie.
Another example of an NP problem is figuring out how many stars there are in the sky. Say you have a guess, then to see if your guess is correct all you have to do is count all of the stars in the sky, which is "easy".
P is the family of problems whose solution is easy to find. Again, it was easy to find a solution to the cookie problem so that problem is in P.
Now, if P = NP then every problem whose solution can be easily checked can be easily solved. But if P does not equal NP then there are problems that can be easily checked but can not be easily solved.
No one knows for sure which one is the case, but many people believe that P and NP are different. And because it has not been proved, we can't give an example. That is because if we could show one problem whose solution was hard but checking it was easy then we would have proved that P does not equal NP.
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ELI5: Why does eating expired meat make you sick even if you cook it well enough to kill all the germs? | Certain bacteria produce spores when they're within certain temperature ranges. Like when you cook meat and let it sit out at room temp for a while. This is when those spores go wild. When you reheat the food the bacteria is killed but the spores are resistant to cooking temperatures and will survive, eventually making you sick. In other instances you can have bacteria that grow and produce toxins. When you reheat the food, the bacteria toxins are not destroyed and can cause food poisoning. | 29 | 18 |
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Is Daniel Dennett's "Consciousness Explained" worth reading still, in terms of being up-to-date? | I'm listening to The Tell-Tale Brain on audiobook. I'm thinking of getting Consciousness Explained next. My concern is that it's a bit of an old book, and the supposed explanation of consciousness may be outdated. Is this the case?
I'll be getting it on audiobook as well, if you have anything to say about that.
Thanks! | The "pandemonium"/"multiple drafts" model he describes in the book is still the favored model for consciousness for Dennett and it remains influential in the field. Moreover, Dennett's primary aim in the book is to deflate a common sense view of consciousness in order to make the computational models in neuroscience make sense from a philosophical and first-person perspective. So, even though philosophy of mind has moved to new territories of dispute and new concerns (e.g., dynamic and embodied models of cognition), CE still has foundational significance. Besides, it's just a great book to read. Dennett has a way with words. | 12 | 22 |
Eli5: Why are our tears connected to our emotions? | Humans are very social creatures, and to be social creatures before spoken language existed required Physical things to convey information to one another. Tears (along with the sound of crying). Are a way to effectively communicate that soemthing is wrong/you’re in distress. | 13 | 18 |
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Eli5: Voyager II | With the Voyager II spacecraft millions of miles from earth and continuing on, how are we able to send/receive data from deep space? | There's a number of factors involved in allowing the Voyager probes to be able to communicate out so far.
**very large antennas** - Voyager uses a antenna 14 feet in size, and the opposite antenna on Earth is 34 feet in size. Which is 10-30 times the size of your usual satellite dish.
**directional** - The antennas are aligned to be pointing directly at each other, which increases the chances of relieving a clear signal
**interference** - The radio channels used by Voyager are very quiet by human standards, this cuts down on interference. If we had used a common band like 2.4ghz for example there would be so much interference that we couldn't hear Voyager.
**power** - the radios use a lot of transmit power. The radios on Voyager are 23 watts compared to the 3 watts of the average cellphone. But even this is pretty weak Big radio stations on Earth transmit at tens of thousands of watts and still fade out quickly. This is the benefit of transmitting through empty space, the signal is less likely to degrade. The transmit antenna on Earth however is several tens of thousands of watts to make sure Voyager can here us.
As for receiving from Voyager it helps a lot that we know exactly where Voyager is, and what it's transmitting. | 61 | 31 |
How do scientists estimate how many species have yet to be discovered? | There are quantifiable species-area relationships. For example, in a given area, there are a finite amount of resources, let's say, bunny rabbits. A coyote needs some number of bunny rabbits to eat. One can then estimate the maximum number of coyotes if you know the number of bunnies. This can be extrapolated out to number of species in the same trophic level, which is to say, bunny rabbit eaters. somewhat of an oversimplification, but that is the gist of it. | 78 | 223 |
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ELI5: why did two sexes become necessary for procreation instead of one that handled both aspects? | genetic diversity. what you suggest is asexual reproduction which many bacteria and some aquatic life here and there do. the issue is that every copy is more or less identical to the first. why is that bad? well, a single disease could now wipe out an entire population. more so no form of reproduction is without glitches here and there and now that bad trait will be copied for every and the species ability to survive decreases.
sexual reproduction ie mixing of two brings in a lot of diversity in the gene pool. yes certainly you can get all the worst traits mixing but you also get a case where all the best ones can mix and you get a super awesome offspring who will go on to likely make more super awesome offspring. that's why sexual selection is such a big thing. they want the best mate to ensure their offspring has best chance of surviving. why mutts ie dogs of unknown breeding are usually much healthier than purebred dogs. they are mixed with everything and are likely to be really hardy and resistant to a lot of stuff. | 62 | 33 |
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[The Matrix] Are humans the only lifeforms populating the matrix? | What about apes or monkeys? Dogs and cats? | The machines were, at the end, made to protect and serve humans. Not apes. Not dogs. Not any other living being. Thus when the war came, and the Machines decided that protecting humanity meant putting them in the Matrix, other animals were not part of that plan. | 22 | 33 |
ELI5: How do we construct things in water? Things like bridges or roads that need support pillars that go into the water. If they're made from concrete, how does the concrete ever dry if it's underwater? If it's in the ocean, does the very bottom of the pillar touch the seafloor? | Concrete curing is a chemical reaction that actually requires water to complete, although excess water in the mixture can yield a weaker cured concrete. Special concrete mixtures are used which are more resistant to chlorides (when pouring in seawater), and care is taken not to agitate an underwater concrete pour too much so that the mix doesn't thin out. You don't need concrete to dry to cure it. In fact, keeping a pour damp throughout the curing process will generally lead to a more complete cure, because the process generates heat that can evaporate water away from the surface, leading to slightly weaker concrete at the surface. Underwater you don't have that problem, though you do need to take care to keep the concrete and the surrounding water at its surface from being agitated and intermingling too much.
Bridge pillars and the like are often constructed using caissons, which is like a waterproof shoring form that extends to the riverbed / seabed, and then has all the water pumped out so that dry construction techniques can be used. | 17 | 24 |
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ELI5: Why do we use total internal reflection for fibre optics instead of just ordinary reflection? | I'm a teacher and I gor stumped by this today, couldn't find any answers with Google. | At ordinary reflection angles, there is both transmission of light and reflection of light at the surface between the two types of material.
At total internal reflection angles, there is no transmission of light, only reflection.
This is important for optical fibers because ordinary reflection will mean light is lost when it transmits through the fiber rather than remain reflected within the fiber. Since optical fibers can span thousands of miles, any little bit of loss per reflection will greatly reduce your optical signal over a distance.
With total internal reflection, you don't get losses from transmission. Interesting enough, if you bend an optical fiber too much, the light going through it doesn't reflect at the internal reflection angle. If the light is visible, you can actually see it transmitting through the bend in the fiber. Optical fibers cannot do the sharp bends possible with metal electric wires. | 13 | 19 |
ELI5: Why is the coin grading system a scale of 60-70? That seems like a rather odd range. | The scale was originally proposed by William H Sheldon. Since no such scale was widely in use at the time he had a very wide amount of leeway in choosing what the scale would look like. Ideally the scale should have enough different grades that you could have a good idea of how worn a coin is, but few enough grades that there wouldn't be a bunch of disagreement between experts as to what the grade of a coin actually is.
That sweet spot is not necessarily aligned with a nice round number that you might hope for, like 50 or 100. 50 was too coarse of a scale for Sheldon, apparently, and 100 was too fine, so he settled on 70. Since he was the first to propose a scale that gained traction (originally just for large cents, but it can be extended to other coins) it became the industry standard, with a few minor modifications over the years.
Note that the scale doesn't just run from 60-70, as your title may suggest. The scale runs 1-70. It's common to see coins only listed between 60 and 70 as those are the highest grades and are the range where you could describe a coin as being in "mint condition." Also, proof coins (struck more slowly and carefully with polished dies) typically land in this range. Most coins are much worse off, but if you have a poor condition coin like that then it's not as common to go get it graded. A coin from the last decade in MS-68 condition may fetch a premium, but the same coin in AU-50 condition is just worth its face value, so it's silly to pay to have it professionally graded. | 45 | 64 |
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[ST:Voyager] Where does the USS Voyager get all of those photon torpedoes from? | When the USS Voyager first became lost there were serious supply issues. Photon torpedoes pack a whole lot more punch than a phaser bank due to their 1kg antimatter warhead, but torpedoes are in limited supply. Once the torpedoes are depleted there's no more to be obtained.
At first, Voyager's crew was very reluctant to use torpedoes. After a while they became very free in using torpedoes, to the point where torpedoes were being used on a regular basis and even became the weapon of choice.
Replicating the parts to build a torpedo housing is something I can understand. Its energy expensive but its doable. They also did this to build new shuttles. However, a torpedo housing without a warhead isn't very useful. That warhead is pure antimatter.
As Voyager is continually low on its power, where does this antimatter come from? Every kg of antimatter used to construct a new photon torpedo means one less kg for the ship's warp core.
Power reserves are often times critically low, and yet Voyager still seems to be able to fire photon torpedo spreads at any time without concern to remaining ammunition.
Where is it getting all of these torpedoes from? | During the first part of their return, personal logs were filled with mentions of the criticality of resupply operations. Later though, as the situation settled somewhat, the drama of needing to be constantly resupplied wore off, primarily because it became much easier to barter with civilizations other than the Kazon. Many crewmen, including the senior staff, ceased discussing these now routine supply operations in all except regular status reports.
One good trade with a warp capable civilization easily provided enough to "top off the tanks" as it were, including the storage bottles for fabricating new photon torpedoes. | 24 | 16 |
ELI5: what determines whether a substance is solid liquid or gas at room temperature? | Intermolecular forces. Some molecules like to stick together, others don't. If they really like each other, they form a solid. If it's more like a friendship they form liquids. If they rather stay away from each other they form a gas. You can force molecules together by cooling them down, which decreases their ability to move around. Or you can increase the pressure. What determines wether molecules like each other or not? It depends on their chemical structure. Some molecules, like water, are polar. They are like tiny magnets that attract each other. Water molecules bond together at room temperature, but they still have enough energy to move around a bit, so that's why water is a liquid and not a solid. | 16 | 15 |
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A lot of drugs are derived from plants. Why not just eat the plants? | I keep hearing about new wonder drugs derived from plants - many of which seem to have long-known (according to local tradition) curative properties. If that's the case, then why not just use the whole plant? Is there a good reason, apart from making Pfizer and GlaxoSmithKline a lot of money, that the source material just doesn't cut it? If its just a concentration thing, couldn't you just eat lots of it to get the same effect? | There are a few reasons for this. By the way, microorganisms also produce a lot of drug compounds.
Firstly, the concentrations of active compounds are often low, and nobody wants to eat vast quantities of plant material to get an active dose.
Secondly, the concentrations of active compounds often varies greatly between different batches, so there's no way of knowing how much you're getting.
Thirdly, the plants may contain other compounds which are poisonous or have unwanted effects.
Finally, compounds taken from nature are usually not ideal drugs - they are usually chemically modified to optimise their beneficial effects and minimise side effects. | 43 | 22 |
ELI5: What stops people in the patent office fron rejecting an idea and patenting it for themselves? | If they patent it themselves, aside from the difficulties they would have in explaining it to others or higher ups at the office, the original claimant can present his receipt and dated file that shows exactly how and when he came up with the idea, the implementation, and the submission date/time.
These two would be more than enough for the immediate firing of that clerk. | 239 | 176 |
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ELI5: In high school, why do teachers make you do projects but give you the determiner "Only 2 of the x resources you use can be from the internet?" | Small backstory, I had to help my niece do a science project for high school. She had to quote sources for a specific physics problem and her solution and how she got there.
I found all of the sources online in 5 minutes and she got her project done in around an hour. However we then had to spend 4 hours driving to various libraries to "prove" she did not get the sources from the internet.
TL:DR I got sources for my niece's project from the internet and spent 4 hours driving to various libraries for library reference cards for the books I found online. | Because the teacher wants some way to ensure that students know how to get information from books or other printed materials.
The internet is a phenomenal resource, but it's important to maintain some small ability to locate information without the internet, like at a library. | 57 | 22 |
CMV: if you can't afford living in an expensive city, you should move out. | Most big cities are becoming prohibitely expensive to live in, making it hard for middle class people to afford a home or even rent. I'm from Canada where this phenomenon is getting progressively worse in cities like Toronto or Vancouver.
And yet I rarely hear of people talking about moving out. I don't really mean the suburbs here (traffic sucks), I mean really moving out. There are tons of smaller cities where housing is affordable and traffic non-existent.
I can see many reasons why some people might chose the expensive city despite their limited budget, but I can't help thinking many people should consider the option of a smaller, more affordable city. I think there's a decent amount of irrational reasoning here, such as "the city is all there is, everything else is just farms and stuff."
Sorry if that make me sound like a smartass. I am biased here because of my own positive experience with growing up in the big city and leaving it for a smaller one. I'm looking at my city friends who have all stayed there and are now struggling with making ends meet and I'm trying to understand their point of view. | Moving is often suggested as the solution for many problems, but the fact is it's an incredibly difficult process for most people, particularly the low-income. Aside from the expenses themselves (moving trucks, etc) looking at available places in other cities/regions means taking time off work, which could be impossible or lead to getting fired.
Also, the advantages of being physically near your network are huge. Not only is it daunting to leave everyone you know behind, family and friends can be resources for favors like childcare. Giving that up is a big task, and puts a lot of strain on people that may not be worth the savings.
Plus, moving to smaller town often means lower wages, and fewer opportunities for career growth. There are exceptions, but generally it might not be fiscally worth it to move to a small town because you're going to start living on small-town income. | 45 | 32 |
How does the body 'learn' from immunosuppressants to keep an autoimmune condition in remission? | For autoimmune conditions where the treatment is immunosuppresants to get the condition into remission, it would seem intuitive that the moment you stop taking the immunosuppresants the condition would return/flare up. But in some cases remission is maintained even when you stop taking the immunosuppresants, which seems counter-intuitive. How does the body 'learn' to stay in remission without the drugs? | For the sake of clarity this is may be a little oversimplified. In the normal immune system, your body essentially has two broad ways of avoiding autoimmunity and eliciting immune responses to harmless substances. The first is central tolerance, in which developing lymphocytes that turn out self-reactive are killed, made anergic (inactive), or induced to become central T regs (which inhibit immune responses rather than activating them). Lymphocytes that make it through development without recognizing self-antigens are able to go out into the body and carry out their functions. However central tolerance isn’t perfect and numerous harmless substances, particularly those that come from the environment, can still be recognized by our immune system. Therefore we have a mechanism of peripheral tolerance in which our already developed and functional lymphocytes can be removed. The oversimplified explanation of how this works is that if a lymphocyte recognizes a substance in the absence of “danger” signals that come from pathogens or tissue damage, it will be killed, made anergic, or induced to become a Treg similar as in central tolerance.
So going back to your question, it is speculated that SOME immunosuppressants (depending on their mechanism of action) may be able to allow SOME people to build peripheral tolerance to SOME graft/self antigens because the antigen is present for long periods of time without any danger signal.
Edit: it’s also worth mentioning that autoimmune/host-vs-graft responses pretty much inherently lead to release of “danger” signals via the tissue damage they cause. So it’s a bit of a self-perpetuating cycle that immunosuppressants help interrupt, as mentioned by another user. By turning off the immune response, you reduce the presence of danger signals, which may be more conducive for peripheral tolerance induction | 21 | 31 |
ELI5: why are new programming languages always being created? | It seems like there are new languages "out" every year or two - what do the new ones do that old ones couldn't? | Programming languages are changing in two dimensions over time: abstraction and specialization.
Computers, when you get right down to it, can't actually do much: just basic logic and arithmetic. Back in the day, "programming" was writing down a series of these basic instructions that would do something useful, like calculate a logarithm. But what's truly useful about that program is that anybody can copy and use it. Instead of writing your own instructions to calculate a logarithm, you just use the instructions someone else already came up with. Now nobody writes the code to calculate a logarithm themselves (outside of programming exercises). Modern computer languages just let you type something like "log(x)," and they do the rest of the work. Over time, we built up a bigger catalog of useful stuff computers can do and also had new ideas about how to best organize and implement all of it, so those ideas are periodically incorporated into new languages (or major updates to old ones). Also, using someone's off-the-shelf code is sometimes inefficient relative to writing something from scratch that is optimized to your particular application, but as computers get more powerful, there are fewer and fewer use cases where this is a concern. All of this means that modern programming languages are thus much more abstract (and also generally easier to use) than old languages like C or BASIC.
The other dimension is specialization. Someone working with data and statistics is likely to use tools like SQL, R, and SAS. Someone working on a website is likely to use tools like HTML and PHP. These languages/software come with built-in tools that make them easier to use for certain tasks. You maybe *could* build a webpage with R or a database with HTML, but it would be incredibly difficult. Other languages, like Python and Ruby, are much more general, and with the right add-ons can approximate many specialized tools, but finding and learning those add-ons is often not worth it (relative to just using a specialized language) for someone whose job only involves one specialty. | 39 | 19 |
ELI5 If high blood pressure is caused by your heart overworking itself, why does exercise which force your heart to work harder lower blood pressure? | **EDIT** ADDING INFORMATION
Thank you all so much for the responses. I learned alot and got more clarity about blood pressure. I'm 32 years old with Ortho-Hypertension (one doc told me). I seen multiple cardiologists, pulmonologists, PcPs, and neurologist and gotten plenty of CTs, MRIs of almost every part of my body, multiple stress and echos., and all types of blood work. My blood pressure at rest could get as low as 120 or as high as 140/80 but slight movement would cause it to jump to 160-180/105. I take 2 medications on for but I had a ton of allergic reactions to them so it's hard to dial in on what I can take and what's causing the issue. While I do exercise I think I will put more time into it, I was just concerned that putting more work would cause it to climb. Thank you all sooo much!! Wish I could express my gratitude as I been fighting this situation for the past 5 years. | High blood pressure is more complicated than that. You might think of blood pressure like body temperature, where there's a set point that your body is trying to keep. We want enough pressure that every organ gets good blood flow (especially your brain, since you have to pump straight against gravity to get from heart to brain) but not so much that we over-stress the system or burst a vessel.
A lot of things go into what your blood pressure is at any moment, and all are regulated different ways:
\*How much volume is in your arteries and veins. From a pressure point of view, blood is basically saltwater. Plenty of salt and water live other places in the body, so this can vary more than you'd think.
\*How blood is being pumped. The heart can vary both its rate and how hard it pumps.
\*How hard arteries are pushing back. Arteries aren't just dumb tubes like the plumbing in a house. They're lined with smooth muscle which can relax or contract, decreasing or increasing pressure.
Chronic high blood pressure is what we worry about. Because the body is normally so good at regulating blood pressure, having chronic high blood pressure generally means that slow processes over time have altered that set point. This can involve changes in the stress response system, the kidney systems that regulate salt/water volume, changes in the lining of the blood vessels, and changes in the heart. Exactly why high blood pressure happens is a huge area of research and gets really complicated (and a little controversial, especially when we talk about salt in the diet.) We do know that regular exercise is part of keeping that healthy regulation of blood pressure normal.
Exercise can indeed briefly raise blood pressure (for accurate blood pressure measurement, we like to have people sit quietly for five minutes.) But our goal isn't to bring down blood pressure immediately. We want to slowly bring it down over time and keep it down. Exercise has positive effects on the heart, the blood vessels, the brain, the stress response system, and much more. Humans are meant to get exercise, and not getting exercise is probably a huge part of why many people get high blood pressure to begin with.
**TL;DR: Exercise may raise blood pressure short-term but improves control over the long term. Bodies can't regulate blood pressure too good if they sit all day.** | 2,881 | 6,935 |
How does exercise reduce your resting heart rate? | Does it make your cells physically need less oxygen? Does it make your heart more efficient, how? | The ventricular walls will also thicken, increasing the contractility of the heart. This increased power in turn leads to a greater stroke volume (amount of blood pumped per contraction).
The cardiac output is further defined as heart rate x SV: hence functional cardiac output can be maintained at a lower heart rate with increased stroke volume. | 17 | 16 |
ELI5:How is it that the US's economy is doing well, but paychecks are growing at a "record low pace?" | Production per hour of labor is increasing, but the increased income from that productivity is mostly going to the shareholders and company executives.
This trend will continue as long as people are willing to work for the same low wages as before. And before people start pushing for higher wages, the unemployment rate has to decrease. It's hard to ask for a raise when you know that there are 100s of people to replace you at your current wage or below. | 38 | 36 |
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Eli5 Why can’t cancers just be removed? | When certain cancers present themselves like tumors, what prevents surgeons from removing all affected tissue and being done with it? Say you have a lump in breast tissue causing problems. Does removing it completely render cancerous cells from forming after it’s removal? At what point does metastasis set in making it impossible to do anything? | Some cancers can be, but the surgeon has to balance getting all of the cancer and none of it breaking off and not damaging the rest of the organ where the cancer is which may be keeping the person alive. | 2,397 | 2,618 |
ELI5: water storage in aquifer. Is it possible to put water back into a natural aquifer for storage? As it sounds as though we are draining many basins, but also building new water storage projects, can we not just use existing aquifers? | Yes, this is possible and being done in many areas. In Portland, Oregon, for example, large pumps in the Columbia River inject water into a shallow aquifer during winter high flows which is used for the city water supply in late summer.
Several factors govern the feasibility of this storage method: the depth of the aquifer, the porosity of the geology, the rate of water withdrawals, etc. if the aquifer is deep below ground, pumping costs may be prohibitive. If the geology isn’t porous enough, the recharge rate may be too slow to store much water in the near-term (natural recharge of aquifers can take hundreds - thousands of years in many cases). In many areas, water withdrawals from aquifers are so large that it is impossible to replace the volume of water removed. These are ‘overdrawn’ aquifers where the water table drops every year with associated pumping cost increases. Eventually, water quality and volume degrades to the point it is no longer worth pumping. | 47 | 54 |
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Essential cultural theory texts? | Hi Askphilosophy
I have recently been accepted into my masters programme in Modern Culture, and would like to get a head start on reading during the summer, since i have quite a lot of time on my hands. Unfortunately, the reading plan for the semester wont be available until late august.
Does any of you with experience in the field have some texts, books or articles that would be considered essential on this topic, or that would put me on the right path?
I have a background in Communication Studies for those interested.
Thank you so much
| You should probably check out the Frankfurt School and Bourdieu as they are major sociological figures In the study of culture. Two books stand out for me as classics on the subject, Dialectic of Enlightenment by Adorno and Distinction by Bourdieu.
| 15 | 20 |
ELI5: How does dust affect the computer? | Additionally, why does it seem like the performance increases when I clean the dust out of my PC? | Dust makes the system hotter, both by directly insulating the cooling surfaces and by restricting airflow. If you remove the dust, the cooling system can run more efficiently, which lets the CPU boost its clock rate. Dust *literally* makes your system slower. | 15 | 17 |
ELI5: Why do drug stores have tons of reading glasses in varying intensities (for farsighted people), but no pre-made glasses for nearsighted people? | If you are nearsighted, you can see close up but not far away - so to do something like driving that requires good vision means that you need an accurate pair of glasses to fix your far vision. If you have the wrong strength of glasses this means that you won't be able to see correctly at distance. As you may not be able to always change the distance between your eyes and something far away enough, the prescription needs to be perfect to see (think about trying to look at a landscape where everything further away than 50m is blurry because your prescription isn't perfect).
Being farsighted means you can see things far away, but your eyes get worse looking at objects close up. If your eyes are such that you can see well a meter away, but cannot read a book sat on the table on front of you, a pair of reading glasses will correct your vision so that you can clearly see something that is closer to your eyes. The differing strengths will alter this distance to different degrees, so a weak pair of glasses will allow you to read 20 cm closer, a stronger pair 50 cm closer, and a pair that is too strong may adjust your eyes too far and make them worse. With something like reading however, you can easily adjust the distance between your eyes and the object you are reading - so while a pair of glasses that are slightly wrong may not allow you to read something 30 cm from your eyes (such as a book laying in bed), they may adjust your eyes just enough to read a book 40 cm from your eyes, so you can just hold the book 10 cm further away to compensate.
So if you find you need reading glasses, it is not so necessary to have a perfect prescription, and you can happily use glasses from the pharmacy (which are typically sold in half steps of strength, where prescription glasses can often be sold in far, far greater accuracies - steps of 0.01 rather than 0.5)
An optometrist will test you and prescribe reading glasses properly too, just this accuracy costs money and many people will happily make do with store bought generic glasses.
One other thing to mention is how people wear glasses and how easily damaged they will be - short sighted people tlypically wear glasses permanently, so when you put them on in the morning you wear them for the day. Far sighted people however will only wear glasses when reading, and will take them off when using distance vision (such as driving). Because they are taking them on and off regularly there is a far greater chance of losing then, forgetting them, or sticking them in a pocket and breaking them. If you have to replace them regularly then the cost of prescription glasses will add up very quickly, so cheap generic glasses will save your a lot of money. For a near sighted person that will often wear the same pair for years at a time without losing them the cost is far more justifiable. | 7,407 | 13,416 |
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ELI5: Why does wood burn when you heat it up instead of melting? | Not just wood, but many things burn instead of melt, whereas other things melt instead of burn. Can you burn ice? What if you put ice in wood? | There are two major forces at work here. The first is the chemical bonds themselves. This would be the carbon-carbon and carbon-hydrogen bonds (among others) that hold a single molecule together. The other force is intermolecular forces, which hold a bunch of molecules together into a cohesive unit. As an analogy, chemical bonds are what make Lego pieces hard to break, while intermolecular forces are what make an entire Lego structure hard to break.
When you heat something, you're putting a lot of energy into it, in the form of vibrations. These vibrations strain against both of those two forces.
If the chemical bonds break first, you get combustion. The individual atoms start flying apart and shedding energy as heat before finding something else to bond with (usually oxygen).
If the intermolecular forces are overcome first, then the thing melts. Molecules start sliding against each other, and the entire structure starts to "flow" like a liquid. | 242 | 132 |
ElI5: Why do you ‘double over’ or hunch over when you have a stomach ache or have eaten too much? | Why do you hunch over when you have a stomach ache or have eaten too much? And why does groaning kind of make your stomach feel better when it’s aching? Could you be hunching to take pressure off of it or something..? But then wouldn’t groaning put that pressure back on?? | Your body's natural response to pain is to contract muscles. On the same token, your body also compels you to apply pressure to injured areas because of survival instincts telling you to reduce bleeding.
It turns out that entering the fetal position 1) allows you to contract your muscles without needing to stretch them and 2) applies pressure to painful areas by contracting your muscles.
Your body works in a strange way where your nerves are very easy to saturate with a signal, so your best bet when in pain is to apply pressure because the pressure can essentially help to reduce the pain that you feel. The fetal position is just a natural response to apply as much pressure as possible to your groin/stomach area. | 39 | 32 |
ELI5: How does your DNA know where it is in your body and which body part to grow into? | Some parts of your DNA are regulatory genes. They don't build anything used for tissue or enzymes or anything like that. Instead, they build proteins that activate other parts of your DNA. So, say your DNA is trying to build an eyeball. It doesn't immediately start making an eyeball. Instead, there's a gene for "build an eyeball" and that gene turns on another gene that says, "build a retina" and *that* gene turns on *another* gene that says, "build a nerve cell" and so on.
Those regulatory genes are activated by any number of chemical signalers. Some of them turn themselves on and off. So for instance, to build fingers there is a signal that both turns on the "build a finger" gene *and* turns *off* the genes that build itself. So the more of this signal there is, the less of it will be made. So you end up with pockets of high levels of this signal, but they fall off really quickly. So your body builds a finger where those signals are strong, but not where none exist.
Similar signals pervade your body. Signals turn genes on or off which turn on or off other signals, which turn on or off the genes that code for the actual "stuff" that you're made out of. Every type of cell tells every other cell what kind it is, and affects which parts of their DNA is activated, which feed back to that first cell and tells *it* what DNA to activate. Before your cells even start to differentiate, when you're just an embryo barely starting to form, the cells still started with some signals that affect the growth of the cells from that point forward so they *do* begin to differentiate. | 17 | 16 |
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[Comics/Dr. Strange] Can Dr. Strange heal himself and others? Should he? |
In marvel comics we know that magic can do a variety of things for a variety of different effects and this varies wildly depending upon the abilities of the user, the type of magic that is being utilized, and the intention. But there seems to be a persistent issue when thinking specifically about Doctor Strange and how he relates to healing physical injuries for example.
We know in the comics that Doctor Strange initially sought out magical counsel in order to heal his hands and through a series of misadventures ended up doing something else entirely, my understanding being that he either deemed fully healing his hands an unworthy utilization of his talents or He is for some reason unable to do so because of either some great magical cost that it would incur or simply because no spell exists that can do that. I’m curious why this is the case if he can do any myriad of seemingly impossible things like raise the dead or travel time. Surely healing his own hands would be child’s play
I suppose the questions that I want to pose are:
1. If he could and did have the ability to heal his hands back to the original state should he? Would it be right or appropriate for him to do so Given that there are many other people in the world with much worse disabilities or injuries who do not have access to magical means of healing?
2. Further if he has the ability to magically heal his own hands or any aspect of his body that was ailing for himself at will would he not then be bound by his Hippocratic oath to do the same for others?
3. If you think he should heal anyone who requested it it is obvious that he cannot heal everyone everywhere. Would it be morally permissible to teach others on a grand scale how to do things like magical self healing? It doesn’t make sense to make magic an exclusive art, many evil characters already know magic (Dr. Doom, Mordo etc) and many heroic characters already know some level of mystical healing abilities. Why not teach it to anyone who wants to learn? | Your question is an interesting and well thought one. It’s tempting to utilize the common limitations held by magic but to me that seems intellectually lazy. Those common arguments against Strange healing himself being:
1. He is simply uninterested in doing so, having morally evolved as a person
2. There is no reason for him to do so, magic does not require well functioning hands or is indifferent to disability to work properly
3. The magic required to do such a feat is deceptively complex and would require a Faustian bargain of some kind that Strange deems unworthy of the cost
It is quite clear given his ability to do feats that would well dwarf something so simple as healing his hands are things he does with some manner of regularity, I.e. battling demons, traveling between dimensions, flying, teleportation and conjuring among many other things.
The simplest rationale that answers all your questions would be perhaps that he does not heal either himself or others because he deems such to be an abuse of his powers or he would not find it morally feasible to heal some people but not others, assuming charitably that such healing would come with no undue repercussions | 20 | 35 |
ELi5: Why are Prince Rupert’s drops so indestructible? | I’m very curious. | Might be a bit off the ELI5, but I'll try:
Due to rapid cooling of the outside of the drop it shrinks. (insert human analogue)
Not only does this shrinking occur all the way around (more or less) at once, it also means that the material has no where to go. Cold and hard on the outside, still hot and expanded on the inside; that puts it quite under a bit of - not only existential - stress.
And then the goo on the inside starts to cool down and contracts, wanting to pull the rest in. The rest that is already cooled and would love to move but can't due to being cold.
What have we then? Stuff on the inside that pulls in all it can. Stuff on the outside that gets smushed together because someone couldn't stand to let it relax.
And now you, with your puny hammer, start smacking around. You just don't bring enough energy onto this table of high and unlovely mechanical stresses to throw those molecules out of order. Get a bigger hammer or grow muscles, puny human.
Well, that is until you start to attack the weak spot. The tiny tail that is so fragile, the whole thing explodes. Same thing actually, but here your puny human-arms are strong enough to overcome the residual stresses.
You monster.
We do the same thing for high pressure pipes btw. (e.g. common rail injection)
We blow them slowly up to a controlled pressure way beyond the future operational goal so that the inside starts to deform a bit. Then, after relieving them of that burden, they feel a bit weird, with all that pressure gone and the residual compression stress still there after the plastic deformation.
So, when the actual operation pressure comes along, they just laugh it off because they've seen way worse and won't give in without a fight.
That completely unrelated thing is called: autofrettage | 344 | 150 |
ELI5 Why is finding water on other planets one of the most important things for us to look for in the case that there is life there? | I get why it could be important but nothing else seems to matter when looking for life. | So life needs chemistry to take place to exist.
For chemistry to take place chemicals have to come into contact with each other. A chemical sitting on one rock and another on another rock won't react with each other.
So they need to mix in something.
This best place for chemicals to mix is in a liquid.
Of all liquids water is the best for this to happen in since water can dissolve more chemicals in it than any other liquid.
Hence, they look for water. | 504 | 285 |
How do you avoid being convinced by every philosophy book you read? | I find it hard to not being convinced when I’m introduced to a new philosopher idea, even more if it is about a subject I don’t know much or if it’s really complicated or if it is hard to read. How do you usually approach this new ideas and how do you avoid being too closed or too gullible to them? Is this a common thing? | Good philosophy has the effect of being convincing. If you feel like you're too convinced by an author and you want to know more about whether or not they're right/if you should feel so convinced, try to find criticisms of the author's position(s) | 227 | 340 |
[ELI5] When staring at any object in the dark, the small details on it seem to look distorted and move around. What’s the explanation behind this? | The way that vision cells (rods and cones) work in your eyes is that if a photon interacts with a chemical substance within them, it causes a chain reaction which causes a nerve signal to be sent to the brain. The more often this happens per second, the brighter it seems to us. This is a random process though, and if there's just very little light to see, the chain reaction happens so rarely that things can randomly appear brighter for a split second.
The distrtion comes from the fact that in the center of our field of vision, there are mostly cones, which can see color but aren't that sensitive to light. On the outside, there are mostly rods, which can't see color, but are much more sensitive. So if it's dark outside, the cones in the middle become fairly useless, and you see mostly with the rods on the outside. The distortion comes from our brain trying to make sense of an image with a black hole in the center. | 46 | 71 |
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CMV: whoever leaks the Mueller report or Trump's IRS filings would be committing career suicide and going to prison, but would become national hero(es) by letting the American people know what they deserve to know. | >"Patriotism is supporting your country all the time, and your government when it deserves it."
- Mark Twain
Anyone who does not expect and demand scrutiny of the government are not patriotic. The biggest patriots to the USA are the ones who shine a light, even at great personal risk, on the parts powerful people want kept dark, probably because they have something terrible to hide. To deflect such scrutiny is not patriotic, and is only the work of stooges in an unjust system or blind followers in a cult.
The topic is obviously partisan but that's part of the problem: issues of law abidance are partisan nowadays. It should never be a partisan question. Love Trump or hate him he should not be above the law. If you are willing to rationalize why or how Trump does not deserve the same scrutiny as anyone else in his position, then you are part of the problem because he obviously owes us that. Anyone in power does.
And when we make the law a partisan issue, we all lose, because it shows that power is more important than playing fair. When people see those in power as illegitimate, social stability is the victim: why do I have to follow the rules if the guy with power and money doesn't have to? For those who take the cynical view that it has always been that way, then they are simply admitting America is not a meritocracy.
But should be.
And those who really love this country and its principles are those who make that so, by divulging what the powerful want hidden, no matter how large the personal sacrifice. Which makes them the greatest kind of national hero, by definition.
| Have you considered the question of admissibility of evidence?
Suppose there is evidence contained in the report / returns that could lead to criminal charges. To make those charges stick, there needs to be a proper court process, where defending lawyers have an opportunity to review prosecution's evidence. Admissibility of evidence needs to be discussed, and decided in closed court hearings.
Now, suppose the report / returns are leaked. One consequence is that some inadmissible evidence is now known to the public, and will sway any potential jury. It provides additional avenues for the defense to argue for delays, and makes it harder for the prosecution to convict the guilty.
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CMV: A college education is not a right it’s an investment. | I hear lots of democrats saying that a college education is a right and therefore should be free. However I think that it is a privilege and that the taxpayer should not be paying for it.
A right is something that is essential to life, e.g. Freedom, right to thought, right to religion. My first point is that 70% of Americans do not have a college degree but still manage day to day life and to earn an average salary of $28 000 a year. More than enough to live on.
My second point is that it increases potential income dramatically and therefore should be considered an investment. The average college graduate makes $51,000 a year and clearly can pay off their student debt. If the taxpayer paid for it we are essentially paying for other people to make more money. | Well, it's an investment, but the real question is who should be making that investment, because individuals are not the only ones that benefit from that investment.
In a country with decreasing need for unskilled labor, and increasing reliance on higher skilled labor, it is a worthwhile investment for that country make to have a higher percentage of their citizens have a college degree.
At that point, the question of "rights" comes in, because there are a lot of ways that social problems create inequalities in who gets to benefit from that "investment", whether the investment is primarily individual or primarily societal.
Having *equal opportunity* to benefit from the investment in college educations seems like a very important "right" that we should protect. | 46 | 75 |
[Kaiju movies] Why does the Air Force insist on dogfighting with monsters? | Why does the Air Force insist on dogfighting with monsters that can slap down planes? I understand the need with the first kaiju in history, good old King Kong: World War I biplanes could do nothing but shoot straight going for the target.
But now wouldn't it be time to update the doctrine? Modern flying gunships (such as the famous AC-130) can safely hit a target the size of a building while standing thousands of feet above the ground, unreachable by even the most gargantuan kaiju. Not to mention missiles.
Is it possible to find a Watsonian explanation for this inexplicable suicidal aspiration of fighter pilots in kaiju-movies?
Translated with [www.DeepL.com/Translator](https://www.DeepL.com/Translator) (free version) | The short answer is that once they fire all the missiles, start lighting into it with the guns, and realize they're accomplishing squat, a pilot can do one of two things: A) say "fuck it" and go home, leaving the ground-pounders and civvies to die or B) start buzzing the monster, because the two seconds it wastes swatting at your plane is two seconds more that the folks below have to run, hide, or dig in before the monster resumes it's grim work. Getting close enough to swat is hella dangerous, but it could save lives and risk-adverse people don't tend to become fighter jocks to begin with. | 59 | 68 |
ELI5:How do we know how certain battles took place? | I just watched the newest HistoryMarche video and it got me thinking. How do we know the details of a battle so thoroughly that we can make a video and present it? Like what flank collapsed, what flank held on.
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I understand primary sources, secondary sources etc. but how would someone know. Was there a guy just interviewing the survivors after the battle, sitting on the hill watching and noting the battle? | Depends on the battle. For more recent conflicts like the colonial wars of the 18th century and later there is often meticulous note-keeping by commanders on both sides.
During the imperial age nations understood the immense value of detailed understanding of your army, your opponents army, and the relative strengths and weaknesses of each. Military leadership tasked officers with this specifically, and commanders filed post-combat reports detailing their actions and thoughts.
As a result, we have *extremely* detailed records of battles in conflicts like the US Civil War and WWI, right down to the exact number of men and what time of day things occurred.
Once you get into pre-industrial conflicts the record quickly gets a lot spottier. Records are sparse, lost, incomplete, and/or heavily embellished. Many medieval and classical battles are known only from a single secondary source and some archaeological evidence, and the numbers and details some guy wrote about 45 years after the fact are deeply suspect. | 17 | 16 |
ELI5: With one eye you have no depth perception, so why is it when I cover one eye I can still tell distance? | Stereoscopic vision is only one component of how we perceive depth, and not even aparticularly good one! Because our eyes are closely spaced, it's only really good for close depth perception. Combined with convergence (How much our eyes have to look towards one another to focus on a close object) these "binocular" methods of depth perception are really only effective out to about 10 metres.
Monocular methods of depth perception that don't depend on having two eyes include:
* Parallax - things move relative to one another as out point of view changes
* Relative size - smaller things are further away, example in a field of cows
* Familiar size - Ships are big, dogs are middle sized, insects are small. We know this.
* Perspective: Line converge to a point which indicates the size of an object.
* Occlusion: If one object passes in front of another, blocking our vision of it, we have perception of their relative size and so distance.
* Defocus Blur: As our point of focus shifts, different "depths" are resolved in and out of focus by the eye. This gives important depth information.
* Distance to horizon. In a natural landscape, the closer something is to the horizontal horizon, the further it is away. This is a function of our elevation above ground level.
There are more...
So, as you can see, our depth perception is NOT limited to "stereoscopic vision". We use many subtle effects to judge depth. One of the reasons 3D cinema can be nauseating or confusing is because it uses simple binocular effects to "brute force" our perception of 3D, which is uncomfortable when other queues are mis-placed in the footage we're viewing. | 22 | 32 |
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ELI5: What's the biggest/tallest a humanoid creature(giant) could get on Earth and why? | I've heard that giants the height of mountains are impossible because of something to do with blood circulation? Just wondering how tall they could actually get. | It depends a lot on how much leeway you allow for the whole humanoid part and how long you want them to last.
The human body-plan is pretty much optimized for the range of sizes that humans actually get.
There are a couple of medical conditions that can induce people to grow taller than normal, but those usually come with an early deaths.
Even normal very tall people tend to have all sorts of risk factors and health issues and lower life expectancy than shorter ones.
Robert Wadlow is the tallest confirmed human at 2.72m but it basically killed him at age 22.
In the past there existed a species of primate called Gigantopithecus which may have grown to up to 3 meters tall.
Neither Wadlow nor Gigantopithecus really had the same body plan as a normal human. Wadlow was incredibly think and strectched looking and Gigantopithecus would have likely looked more like a scaled up orangutan than a human (we did not find enough bones to be really sure), but both still count as humanoid.
Scaling it up beyond that is difficult because of the cube-square law.
If you take an object (like a human) and scale it up so that it is twice as tall it will have increased in volume by factor of 8 and in surface area by a factor of 4. Since lots of things that make a body plan work depend on the ration of for example skin-surface to total mass being right, you end up with problems. If you make things too small or too big the body will either loose too much heat or too little.
Objects will risk breaking under their own weight if you scale them up because the mass increases with the cube while the ability to carry it only with the square of the scale up factor.
There are lots of other factors that end up not working if you scale it up too much.
Think of the way a toddler can easily deal with running stumbling over their own feet and falling flat on their face. They will cry but mostly come away from the experience with no big harm done. An adult making a similar fall flat on their face from standing up straight will be at far greater risk of injuring themselves.
Scale a human up to the size of a building and falling on their face will basically be a death sentence.
This keeps us from having to worry about giant ants or giant spiders but also keeps us from having giant humans.
Anything much taller than the tallest NBA players is basically not healthy and you would need to redesign the human body to get much taller than 3 m. | 70 | 97 |
[Lord of the Rings] Boromir gets the One Ring and somehow manages to use it to fight Mordor without getting corrupted, exactly what powers does he get? | I don't want to delve deep into the personalities and corruption, i just want to know what powers would he get that are useful in the war against Mordor?
Would his size increase? Would he become stronger? Stuff like that, what would he get?
Because the movies make it seem like you only become invisible and enter the world of wraiths | It enhances your native charisma and ability to exert influence and even dominate the wills of others. It shifts you into the wraith-world (if you don't already exist there) and grands you supremacy over the other lesser rings of power.
But Boromir *would* get corrupted. Even if he could contest Sauron for supremacy over the ring (which he couldn't) he would still turn to evil and seek domination over the world. | 42 | 17 |
CMV: "You create your own meaning" is not a valid response to "Everything you do is meaningless" | The insignificance of everything we do really cannot be understated. Even if you're the most important person on the planet, there will exist people more skilled and more hard working than you, who would easily fill your shoes if you weren't there. If the human species goes extinct, there are lots of other planets with suitable conditions for life, and those under the right circumstances are probably teeming with evolving organisms. Plausibly, there exist an infinite number of other universes with different fundamental constants, laws and other variables that result in radically different universes to ours. There is nothing inherently special about anything, it is all a product of randomness and stochasticity.
So after being presented with the view that everything you do is meaningless and that no matter how significant, important or meaningful you think that something is, it isn't - people usually respond with "You create your own meaning". Which doesn't make sense to me. It's like telling someone that imaginary friends cannot exist in reality, and them replying that you create your own imaginary friends. It's obvious that we create them, but our mind's creations and the truth can be shown to be incongruous.
For the record, I have nothing against people with imaginary friends or people who choose to create their own meaning, I do as well. I just accept that I'm a hypocrite. And to be frank, nihilism often serves as a coping mechanism when things don't go the way I desire. | Consider what it means for something to be "meaningful." To be meaningful is, by its very nature, a subjective thing because nothing matters unless it matters *to* somebody. To say that something is meaningful is to say that it means something to somebody. So it's perfectly appropriate to respond to the claim that everything is meaningless by pointing out that you create your own meaning. If something is meaningful *to you*, then it's not meaningless.
If you're talking about something being meaningful apart it meaning anything to anybody, then you're talking incoherently.
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ELI5: Scientists studied remains of a kilanova (when two neutron stars collide) and measured one of the neutron stars to be 12.4 miles in diameter. | How could they have known it was 12.4 miles in diameter just by examining the explosion aftermath? I saw this on “How the Universe Works” but they never explain the reasoning. | Basically they are able to estimate the masses of the two neutron stars based on the gravitational wave signature. Since we know the density of the stars (they are made of nuetronium, the densest substance in the universe, or what we theorize anyway as we haven't ever created it) we can calculate the volume of the star and then the radius. As other users pointed out, the actual estimation is 20km, and the conversion to 12.4 miles implies a presision that is incorrect, it would probably be more correct to say something like 12-13 miles in radius. | 24 | 49 |
Why do houses have sloped roofs while commercial buildings are flat on top? | roofs of houses are sloped in order for not letting rainwater or snow build up. Commercial buildings however generally have a much bigger surface and sloped roofs wouldn't be feasable, so you need to implement other means to let rainwater run off. | 55 | 86 |
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Why are the Great Basin, Mohave and Sonoran Deserts considered distinct? | Looking at a map, these three deserts look like they are right next to each other. Why wouldn't they be known as one big desert? | Mostly because of distinct plant life and weather. In the Sonoran desert you have several varieties of cacti that are not present in either the Mojave or Great Basin desert. The Sonoran also has two rainy seasons, summer monsoon and winter rains while the other do not. Also separting the Mojave and Great Basin is temperature. The Great Basin is considered a cold desert, whereas Mojave is a warm desert. There are also varieties of plant life, such as Joshua Trees which are plentiful in the Mojave but rarely occur in the Great Basin. Even though they are close different weather patterns cause a division of plant life in them and separate them. | 3,423 | 4,573 |
I do not think it makes sense to tie the salary of a university president to the salary of the lowest paid worker. CMV | There was a recent story about how St. Mary's College is considering a policy that would limit the salary of the president to ten times that of the lowest paid worker on campus. While this sounds nice in theory, it does not make sense from a practical standpoint to keep the college competitive, and for larger and more prestigious colleges (nothing against St. Mary's) it would be a *major* mistake to implement this. Why should the president of a large university make a million bucks? Because it keeps them at the University. Private sector businesses can pay a *lot* more for skilled managers, and while working at a university should not be just for the money, having a reasonable financial incentive to attract the best presidents makes sense. If you are not offering somewhere in the neighborhood of what these people would be making elsewhere (or even at another university), you are going to lose your prestige and edge (which is really what most universities care about the most). | This assumes that salary is the only possible motivator for skilled managers (or skilled labor).
Doctors without Borders doesn't pay well, yet still attracts top-tier talent.
Similarly, contributing to a center of higher learning and being of service to the academic community is often held in high regard by society. For many skilled managers, the privilege of serving, especially at a well-regarded institution, more than compensates for the lost income. This also includes skilled managers who do not enjoy the private sector environment, or are attracted to the academic world.
This principle applies to many government workers as well. There are some very, very intelligent and skilled workers on the government payroll, who could earn a large chunk more in the private sector. However, because they enjoy the work they do, they do not require the additional financial incentive.
Indeed, it could be argued that these workers are even more desirable; offering a lower or capped salary might weed out "mercenary" CEOs or University Presidents who really don't give a crap about education or the University, only the metrics that determine their paycheck. The kind of CEO or President who would leave if a higher paying offer came along is a liability, and only as good as the targets the board sets. A mission-driven University president will work because they truly enjoy it, and may be much more productive and effective as a result. | 119 | 262 |
What exactly is Particle-Wave Duality of Light? | I have read a little bit about Quantum Mechanics and this is a bizarre phenomenon(for someone who didn't take GCSE Physics) that I've come across that isn't explained very well.. So I was wondering if someone can perhaps provide me with a more comprehensive explanation with suitable analogies so that I have a better intuitive understanding of the subject. | Waves and particles are concepts that have quite different properties.
The following are simplistic representations of some of the classical properties of waves and particles:
Waves are considered to be entities that don't have a single position, but are instead spread out over an area. In addition, two waves can interfere with each other and depending on the conditions, this interference can amplify the wave or even extinguish it. A wave can even interfere with itself, for example through it's reflection (throw a pebble in a body of water and you can see the interference of the wave with it's reflection off the edge of the water).
A particle is a discrete unit. You can count them. They have a single, well-defined position and direction. While different particles may interact, they do so in an intuitive way, according to classical mechanics. A good analogy for particle behavior and interaction is a pool table, with the balls (particles) moving around and bumping into each other and the walls.
Whether light consists of particles or waves has been a back-and-forth matter in science. In the 1800s it was discovered that light is a form of electromagnetism and through the work of Faraday, Maxwell and others, light was established as a wave phenomenon.
However, in the early 20th century quantum theory reignited the notion of light as a particle phenomenon. Work by Einstein and later Compton revealed that light had properties that could be explained through particle theory, but not with wave theory.
Eventually quantum physics evolved and the differences were reconciled with the conclusion being that light exhibits properties of both waves and particles. Depending on exactly what you're looking at, you'll find light behaving like a classical wave, like a particle or like something that's neither of those two.
For example, in the dual-slit experiment, a light source is directed at an opaque surface with 2 parallel slits in it. The light passes through the slits and is projected on a surface behind it. Doing this reveals interference patterns that are consistent with classical wave theory, but can't be explained with pure particle theory.
On the other hand, in some instances, light can be measured not as a continuous wave, but instead as discrete units of energy, as if they were separate particles. One instance of this is the photoelectric effect, a phenomenon where certain materials emit electrons when exposed to light. This phenomenon was first explained by Albert Einstein (for which he won the Nobel prize), by considering light as discrete "quanta" of energy.
So there you have it. Particle-wave duality of light means that light behaves as both particle and wave, depending on the situation. However, classical particle and wave theories are insufficient to completely describe light, which is where quantum mechanics comes in.
And as an encore: It's not just light that exhibits particle-wave duality. It's everything. The aforementioned dual-slit experiment also works with electrons, for example. In general, the heavier/bigger something is, the less pronounced its wave aspects are, which is why we don't have to consider the wave properties of macroscopic objects at all. | 25 | 16 |
ELI5: How can something have no calories? What does the body do with this calorie free food? | Calories are a measurement of energy, which comes from breaking bonds between atoms — mostly, carbon atoms. Just like the gasoline your car uses that makes it run (gasoline is primarily carbon and hydrogen). When your body breaks down things like sugar, fat, and protein, it breaks the bonds in it and releases energy that it uses to do various things.
Food has varying amounts of sugar, fat, and protein. A bag of Skittles is almost all sugar. A slab of meat is mostly protein, with some fat. All of those things have calories that come from those compounds, which your body breaks down.
Some foods do not have anything that your body can break down. Water, for instance, has no carbon. It goes in and most of it goes out (in your pee or your sweat). Some foods, like diet soda, have carbon compounds in it, but they are designed so they can’t be used by your body (they create the taste of sweetness but can’t be broken like normal sugar, hence no calories). And other foods have carbon, but it’s also in a form you can’t use — like celery, for instance, which is mostly fiber. It has substance, but (mostly) not a kind your body can break down and use. If your body can’t use it, there’s no energy to gain from it and therefore no calories.
Also, if you consume extra calories that your body doesn’t need at the moment, it uses that energy to make things to store and use later. One of those things is fat (your body can make fat). Then, if you go a while without eating, it will break that fat down and use it for energy. You don’t need to eat fat to make fat. Your body can use anything with calories (energy) to make fat. That’s why you can get fat even if you eat a fat free diet but eat a ton of sugar. | 70 | 29 |
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[Comics General] How do I falsely convince a court that I was framed by a supervillain with mind control or illusion powers? | I robbed a bank and was arrested, but they never found the money. How do I convince the court that I am being framed by a super villain who used either mind control or illusion power to make it look like I did the crime while they got away with the money?
Who would be the best villain to scapegoat?
Would claiming I was under mind control work?
Would claiming it was all an illusion work? | A lot of jurisdictions have an insanity defense by which you have a pretrial hearing to determine whether you were capable of understanding the nature of your crime/your actions at the time (or whatever their applicable insanity defense entails).
So I'd say that's where you start. Presuming there are well known mind control villains in your universe, you'd probably present as much evidence that you could that you were in contact with them around the time. Even if not, your best bet would be to at least fall back on a traditional insanity defense and claim you were essentially legally insane for all intents and purposes. | 26 | 39 |
ELI5: how come if I have a watercooling loop in a computer, it will grow algea even though there's no food or light. What do they survive on? | Heat and micronutrients in the water. Also there is likely some light getting in too (or at least off of LEDs in your computer, it doesn't take much).
Think of algae growth in covered swimming pools and water coolers.
I would recommend using distilled water or a water and glycol mixture to prevent biological growth. This is commonly used in residential and industrial heating and cooling systems.
Have a great day! | 229 | 328 |
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ELI5: Why do most predatory animals choose not to eat humans? | I know it happens, but the vast majority of animal / human attacks never end up in with the human actually being eaten unless there are some dire circumstances involved. I've seen and heard many examples of a person being attacked and then the attacking animal just leaves inexplicably. For example, many shark attacks are simply the shark "tasting" its "prey" when they realize its human they take off. Why is this? Do we taste bad? If so why? Or do animals just know that its a bad idea to attack the most awesome predator thats had ever lived on this planet? | Through evolution, predators become specialized towards particular prey or categories of prey. They develop hunting patterns that take advantage of their prey's behavior patterns (e.g. stalking vs ambush vs pursuit), and learn to recognize certain types of animals as efficient sources of food. Most of this is pattern-matching instinct, built up over generations of trial-and-error selecting the most effective instincts. Animals that tend towards more-efficient prey succeed.
Predators that adapt to specialize towards humans, don't last very long. We counter-adapt on the order of years instead of generations so animals are always behind the curve in terms of efficiency. We also counter-hunt predators for our own safety, meaning that succeeding in predating humans is actually maladaptive, and will be selected against.
Most modern animal attacks are not specialized predation. Often they are self-defense, which means that the animal is not inclined to eat the remains. Hunting humans for food generally happens out of desperation. There are also some instincts that are not specialized towards prey, like the sharks nibbling--I assume that there's a second step where they specialize hunting behavior based on the first bite, and they have no developed response for us. | 50 | 20 |
ELI5: Why do humans like music so much? | Multiple explainations.
Simplest one is that music is an excellent bridge between the 2 halves of our brain. The emotional and logical portions.
Music has an intrinsic mathematical component to it. We recieved "feel good" sensations from interpreting that mathematics into pattern. On the other hand, the creativity required to process music as something more than just noise required use of our emotional processing system.
To simplify, Music pleases both parts of our left and right brain. | 15 | 38 |
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How do we have elements on the periodic table that we dont know the form of in certain temperatures? Are these just theoretical and we have never actually physically seen it? | Any element placed on the periodic table by IUPAC has been formally discovered, meaning that at least one isotope of it has been observed/produced, so its existence is experimentally verified.
However just discovering an element doesn’t necessarily mean that we know anything about its chemical properties. Especially for the superheavy elements, where we produce them using particle accelerators, and they decay in less than a second. There’s not enough time to do much chemistry there to study their chemical properties. We have to rely on theory to predict their properties. | 31 | 22 |
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ELI5: What is a savant, and what percentage of the world's population is considered to be savants? | Typically, people who are considered to be savants excel dramatically at one thing, such as painting or writing. However, they also tend to have difficulties in other important areas, such as social interaction.
Often, savants have learning disabilities such as Autism Spectrum Disorder.
A good example of a savant is Daniel Tammet, who is an Autistic Savant - Daniel is able to count pi to over 22.5 thousand decimal points using only his brain. | 16 | 24 |
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[The Culture]Are the inhabitants of universes simulated by the Minds considered Culture citizens with all the rights and protections thereof? | I know very little about this universe, but I understand The Culture is supposed to be this benevolent utopia. But I understand the Minds like to create simulated universes, and I wonder how this works if it would mean allowing the intelligent inhabitants of those universes to suffer. | This is discussed at length in *Surface Detail* and to a lesser extent in *The Hydrogen Sonata*.
The short version is that it's very mixed, and left to the discretion of the individual minds performing the simulations. The majority of minds consider simulated life to be at the same level of moral consideration as all other forms of intelligent life, and will elect to minimize suffering as much as possible, and will prefer to keep simulations they have created running indefinitely rather than all all of those simulated lives to die.
On the flip side, most biological denizens of the Culture do consider simulated life to be slightly lesser than biological life. Surface Detail describes a war that is fought entirely by mind-copies in a simulated battlefield, with one character having at least a dozen copies of himself fighting side by side on the front lines. This is considered to be preferable to a "hot war" because its entirely a simulation. Although at least one character argues that this is preferable because everyone fighting has actively chosen to take part in the hostilities, and there are no innocent bystander casualties, and not because simulated life is less worthy of moral consideration.
To add more to the mix, other non-culture civilizations who discover mind-uploading technology have decided to use it for imprisonment and punishment purposes. A few religious civilizations have actually gone so far as to create virtual hells, and have uploaded the minds of criminals and heretics into hell so they'll suffer for eternity, just as the good book says. The cause of the war in Surface Detail is that certain factions of the Culture find this to be so reprehensible they're willing to fight a war to force those civilizations to stop it.
>!The driving conflict of the story is that someone is attempting to drag the simulated war kicking and screaming into the real world, where the Culture would have much more of an advantage.!< | 22 | 22 |
ELI5: Schrodinger's Cat | 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 | 30 |
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[Harry Potter] Why are there any students still alive at Hoghwarts? | Why are there stills students alive at Hogwarts? I mean the casualties of teaching magic to kids mast be massive for example:
> "Never forget Wizard Baruffio, who said 'f' instead of 's' and found himself on the floor with a buffalo on his chest."
One letter? Seriously? And this isn't an advance class or anything this is a quote from the first book their **first** lesson in charms. And they are being encouraged to practice after classes without supervision!
Envision that scenario. Kids who most of them never went to school before are tired after a day of classes and go in to there common rooms to practice magic. One slip in the wording, a bust up lip because someone got in a fight and you have an 800 kilogram beast raging the room. The student who summoned it is dead, simply crushed under the weight, anybody else still in live danger until some organised 5th year comes along and makes it disappear or stuns it. The human body needs about 2-3 minutes to bleed out of major vessel, god forbids a big artery is damaged cut that time down to 1,5 minutes. Madam Pomfrey is a 5 minute run away at best which makes any medical help arrive in 10 minutes top. I would say we are looking at 5-8 dead student. In the first week. From one spell. By one student.
Transformation must be even more deadlier. Switch up a word or make a wrong wand movement and you suffocate because you just closed up all your orifices.
Potion brewing - a mistake by ONE DROP made an acid strong enough to burn through an iron pot in seconds. I won't even imagine how much lung damage everybody in that class got. And stealing ingredients isn't difficult at all since there is no control who takes what for most ingredients and the rare ones too(seeing as a second year manage to do it) or it shouldn't be problem to order them by owl to Hogwarts seeing as the one person without magical knowledge or abilities does the package checking.
Eddit: words! grammar! punctuation! ~ me nemesis | Madam Poppy Pomfrey is a highly skill medical technician, versed in a vast number currative incantations, potions and artifacts. She has practiced medical magic at Hogwarts for over 25 years. This provides her unfettered access to the foremost medical texts and continuous, practical experience. Lately, Madam Pomfrey has had a ... higher than average rate of challenges, but from tasting Dementor exposure to regrowing bones, Poppy has meet every challenge with alacrity, competence and skill. Something as silly as a buffalo upon the chest pales in comparison to reversing the effects of a failed Polyjuice Portion.
I bid you a good day. | 29 | 18 |
ELI5: Does lowering your fever using pills make your body fight less against a virus? | I'm on my fourth day of what the doctor thinks most likely is mononucleosis (I only went to the doctor yesterday and haven't got blood results yet) and I got some 600mg ibuprofen to take the worst away since I had a fever of 40,1C (104,18F). This just helped me quite well through a night but got me thinking - did I just delay my recovery by another night or does the body still fight when you synthetically lower the temperature?
*edit: spelling | Fever is one of the responses of the body to infectious agents (and all other kinds of widespread inflammation for that matter). Fever can sometimes be useful to fight off the infectious microbe but the truth is that it's not always the case: fever definitely helps fighting off many bacterial infections (bacteria are small foreign cells that can live on their own) because the higher teperature disturbs the bacteria life processes and slows down the speed at which they spawn. But fever won't contribute that much in the fight against a viral infection (viruses, for example mononucleosis, must take control of our very own cells to spread the infection and do not have their own life processes) because the damage inflicted to our bodies during viral infections is mostly done by our own immune system (in the vast majority of virus types). Moreover, it is clear that when fever rises beyond 40°C the risks it entails for the body are much more dangerous than the small advantage it could provide in fighting the microbes.
Therefore: if you suspect something bacterial in origin and have a high fever, you'll take some drugs that don't hinder your immune system activation very much but at the same time that can lower the temperature: the chief drug is paracetamol (also called acetaminophen, depends on wich part of the world you live in).
If you think that there's something viral going on, then the best strategy is to tell our immune system to "stand down" and not overdo it against the virus, therefore you'll be given some medicine that simultaneously lowers the body temperature AND halts the furor of the immune cells: one such drug is for example the ibuprofen you took.
N.B,: in any case, these drugs do not lower your body temperature directly: they just shut down the transmission of the fever signal inside of our brain: you'll never get too cold :) | 38 | 53 |
ELI5: How do hospitals evacuate everyone in the event of a fire? | Hospitals often have patients who are bed-bound, wheelchair-bound, comatose, or even in surgery. When the fire alarm goes off, how do staff evacuate all patients quickly? | Hospitals are designed so that in the event of a fire, doors will close and will prevent the fire from spreading until firefighters can deal with it. The doors are rated, usually by number of hours, for how long they will hold back a fire on the other side. | 14 | 17 |
ELI5: What is the point of cutting up cancelled credit cards? | Unfortunately, I got my wallet stolen, but I was able to retrieve it back two days later with nothing taken (yay). The only annoying thing was that I had to call all of my credit card companies to cancel my cards the moment I found my wallet missing and request new cards to replace them.
In the midst of disposing my cancelled cards, I was thinking to myself what is the point. The cards are cancelled, so wouldn't it be useless if someone were to copy the information off these cards anyways? The best thing they can copy is probably my name, but it's as generic as John Smith.
I cut up all my old cards properly in the end, but I got curious: Is there a good, credit-threatening reason to cut up cancelled credit cards, since they are obsolete and shouldn't even work anymore? | It can be used to establish an identity, for one thing. For example, a bank account requires two forms of I.D. (in the U.S). A credit card with printed name is an acceptable secondary form of Identification. Also, IIRC, the magnetic strip still contains the information on your account, and many identity thieves have machines that can read/manipulate the magnet strip. The machines with the power to do so are sold on the free market. | 21 | 21 |
How does inflation work, and what are some of the ways inflation can increase? | I have a hard time understanding inflation. When I was a child, I would say the government has all the money in the world, they can just print more of it. My father would reply by saying that would cause inflation. What did he mean? | In very basic terms, the value of money just represents all the things in the economy you can buy. So let's say you have M=money and G=goods(and services). In the short term, it's just G=M, so if M becomes a higher number, and G stays the same, more money is necessary to buy the same amount of goods. That's inflation
Another example, let's say you have 10 money and 10 goods, every good is worth 1 money. If you double the amount of money, you can still just buy 10 goods. So every good is now worth 2 money. | 10 | 24 |
CMV: The fear of illegal immigrants taking all of the jobs in America is illogical. | Since the beginning of this fine country immigrants have come to make a better life for themselves, and this has made America better as well. After a period of time, however, the people who have lived here for a time have begun to feel as if we are letting too many people in, and these people have always complained that the jobs would run dry, and the people who are here already will suffer.
We survived the surge of Irish immigrants, we survived Reagan's amnesty, and we will survive (in my opinion) the new onslaught of immigrants.
The next complaint is that they already have committed a crime by crossing the border. Well, if my kids were starving, and I knew of a place I could better feed them I would jump the fence or swim the river in a heartbeat. Additionally, they may not have to come illegally if it was easier to become a citizen.
I am a conservative in most other ways, but Change My View... | Part of the problem is that as more immigrants enter the country, they drive down the cost of labor; when before, a company may have had to pay it's employees 10$ an hour, now they can hire illegals to do it for 5$. The nationals who used to be making 10$ now have to work for five as well if they want to compete with the illegals, so all labor takes a pay cut. | 14 | 44 |
ELI5: How can asking a sample size of 1,003 people give an accurate view of over 250 million people? | It assumes that you have a properly random sample of the population. Suppose you have a (very large) bag full of millions of balls. You draw out 1003 without looking, and get 600 reds. How confident would you be that close to 60% of all the balls in the bag are red? | 22 | 17 |
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ELI5: When someone experiences memory loss, do they also lose all knowledge acquired during the periods of memory that are missing? | They might lose their memories of events, but they can retain skills learned during that time. There's a well studied man who got herpes in his brain, it destroyed his short term memory. He forgets who he's talking to, what he's talking about, within seconds. Bit he can still improve his artistry and learn other skills. | 19 | 42 |
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ELI5: Why do credit cards have expiration dates? | When modern-style credit cards were first introduced in the 1960s, running a credit check on an individual was a lengthy and complicated business. Although major financial institutions each had their own basic computer systems, there was no interoperability and no way for them to automatically verify an individual's bank account details, lending history, and so on. This all had to be done pretty much by hand, involving much sending of real snail-mail letters.
So this meant that after agreeing that someone was credit-worthy enough to own a card, the card issuer couldn't do continuous rolling credit checks to ensure the cardholder was still good for it. Instead they generally made each cardholder reapply for the card after two or three years. This is why expiry dates were first introduced -- it provided a guarantee for both the cardholder and the merchants that the relationship would get re-checked every few years and so there could be some confidence about creditworthiness.
Obviously if you were starting from scratch these days that wouldn't be the case. But for these historical reasons cards keep expiry dates, it also provides a little extra security in that if a fraudster were to get hold of a card number, then without the matching expiry date that's still useless to them.
| 19 | 22 |
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