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Why do we have an optic chiasm? Wouldn't it be simpler if the right eye supplied the right cortex and the same for the left? | I have found many descriptions of the optic chiasm yet I can find nothing for why it is there. Maybe it has something to do with 3D vision but I don't know enough to come to my own conclusion. | The left brain processes the right side of the visual field in both eyes, the right brain processes the left side of the visual field in both eyes. The crossing over of incoming visual stimuli and the location that this splitting/mixing occurs is the optic chiasm.
It's difficult to ask why sometimes in medicine - it isn't like we have an owner's manual to refer to for a definitive answer.
One explanation might be that this set up is safer. If you sustain trauma or receive damage (stroke, tumor, lesion) to your occipital lobe or optic radiations (or other associated structures) on only one side of your brain past the point of the optic chiasm, you have not rendered one eye totally useless, instead one half of the visual field has been wiped out. Your binocular depth perception remains functional. | 18 | 16 |
[The Martian] How long do you think the other members of the crew would have lasted had they found themselves in Mark Watney’s position, stranded on Mars? | Keeping in mind that Watney was the crew’s botanist and a mechanical engineer.
The other members and their crew
jobs are as follows;
Lewis - Geologist
Martinez - Pilot
Vogul - Navigator & Chemist
Dr. Beck - Surgeon & EVA Specialist
Johanssen - SysOp & Reactor Tech
Given they are all scientists and astronauts chosen to go to Mars, you would assume they all have interchangeable skills outside their speciality. But I would think without botany as a specific qualification, they couldn’t survive nearly as long as Watney did? | Everyone choosed for the mission was surely trained in all fields at least in basics. As we can see in the movie, there are laptops and other documents aroud that can be used to get information about anything. So if a non-botanist crew member wanted to know more about botany and to find a way how to grow something, they could use info from Watney's laptop. | 13 | 17 |
Why is rent control a bad thing? | I don't understand economics like I probably should and i'm having trouble understanding why rent control is a bad thing. I live in Saskatchewan if that makes a difference. | One of the main reason capitalism works is that prices somewhat accurately reflect supply and demand. Rent control takes away this information. As a result, there isn't the same incentive to create new developments. Less new development means less supply, which would increase prices, but they're kept artificially low which compounds the problem. You end up with a situation where the government then has to step in to create new housing, because businesses don't find it profitable.
How disastrous it ends up depends on how out of tune the government rent control is with what the open market prices would have been. This isn't like banking regulations or employment insurance though, it's a reduction of information that never ends well. | 37 | 57 |
Why is cloth darker when it gets wet? | In dry cloth, light gets scattered and reflected mainly by the particles on the surface. In wet cloth, some of the light gets carried into the material by the water, acting a bit like fiber optics. The end result is that less light gets reflected or scattered back.
Consequently, this same phenomenon is why you can see through wet paper better than dry paper. | 61 | 41 |
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ELI5: Why do humans have different bloodtypes? | http://www.bbc.com/future/story/20140715-why-do-we-have-blood-types
This was interesting | If you're looking for the anatomical reason, it deals with the Red Blood Cell surfaces. RBCs are the cells that contain hemoglobin, which act to pick up/drop Oxygen and Carbon Dioxide in the blood stream to metabolically support and "feed" all of the cells in your body. An antigen is a protein on the surface of a cell that acts as a "flag" for the immune system. RBCs in a certain person contain contain types of antigens. In reality, there are thousands of antigens present, but in terms of labeling RBCs, there are 3 important ones: A, B, and D (Rh). A person with a certain antigen of these three would also have blood plasma (surrounding liquid around RBCs) containing antibodies (bind to the antigens) for the other blood types. For example, a person with Type A blood would have antigens for Type B and D Blood. This is why you can't give blood to a person of a different blood type because the antibodies will react with your antigens on your RBCs, causing clumping and apoptosis.
The Rh antigen brings the +/- factor that you often see on blood types. If Rh (D) is present, the type is + and the plasma contains no Rh antibodies. If Rh is not present on the surface, the type is - and the plasma contains Rh antibodies. Effectively, these are the blood types:
A+: contains A, D antigens and B antibodies
A- : contains A antigens and B,D antibodies
B+: contains B, D antigens and A antibodies
B- : contains B antigens and A,D antibodies
AB+: contains A, B, D antigens and no antibodies
AB- : contains A,B antigens and D antibodies
O+: contains D antigens, and A,B antibodies
O- : contains no antigens, and A,B,D antibodies
This would make O- the universal donor blood type because the blood cells contain no antigens for which a recipient's antibodies could react with. AB+ is the universal recipient because it has no antibodies in the plasma that could react with a donor's blood's antigens. | 25 | 228 |
[Any] What super power would best translate into bedroom prowess? | If it's just one power, then mind-reading:
- You can tell who's attracted to you. This saves a lot of time.
- You know what everyone's kink is. This saves a lot of time too.
- In bed, you know *exactly* what you need to do. No more fumbles! | 69 | 26 |
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CMV: Rapidly recharging health bars make first person shooters less enjoyable. | To clarify: I am talking specifically about campaigns. Health that restores quickly makes sense in multiplayer, as it allows each engagement to be somewhat fresh.
For this reason, I mostly emulate N64 shooters and don't play most modern shooters with any frequency or consistency. As such, I am certain that my perspective is limited, and would like to see why at this point essentially all shooters have rapidly recharging (RR) health as opposed to Long-Term (LT) health.
I am currently watching a friend play Halo 4, and he is reasonably frustrated by his inability to beat a specific part of the campaign. His checkpoint is about 3 minutes from when he usually dies, and he ends up redoing the same part constantly. Eventually he succeeds at that segment with minimal feeling of accomplishment, making it to a checkpoint where the process is repeated. Then he ends up spending another 10-25 minutes on that 3 minute segment, reliving the same fights and hearing the same speech pods. This seems unfun to me.
In contrast, playing a game with LT health means that the segments are around 12 minutes long. I remember spending a long time over several days trying to beat Perfect Dark's level "Carrington Institute: Defense." It was neither boring nor frustrating, because with each attempt I played about 12 minutes of unique gameplay and something different happened or I learned something with essentially every attempt until I reached success. Success eventually came with an exceptionally good run that lasted the lenght of the level, nailing all the parts that needed to be nailed in one go rather than piecemail, one at a time until I got to a checkpoint. This success carried a large feeling of accomplishment with it, as a difficult challenge was met where I was staring down complex objectives and enemies with shields and high-powered weapons and was able to take about 2 solid hits before I died. By the time I was able to win, I had a very streamlined process that was precise and required high levels of skill. I felt like the Perfect Agent the game told me I was. This level of quality is unachievable with a RR health system, where hits are frequently taken and shrugged off in seconds.
While Halo at least has in-universe Clarke's Third Law-esque justification, in games like Call of Duty there is the added huge drawback of crushing any sense of immersion in the game. I find it impossible to suspend disbelief through getting shot until I reach the very near to death stage and then being completely fine a second or two later. In contrast, the original Deus Ex had a beautiful system where arms and legs could be made useless by enough bullets until the player was able to heal or regenerate them. Obviously games will always require suspension of disbelief to achieve immersion, but in some settings RR health completely destroys all hope of a quality immersive experience.
For primarily the reasons of length of game segment that is repeated, a more complete task leading to a greater feeling of accomplishment, and a more immersive experience, I believe that single-player first person shooters are most enjoyable without RR health. The fact that finding cover undoes all damage previously taken seems to hurt continuity and just feels lame. Since most games have gone to RR health means the majority of people likely disagree with me. So, CMV. | Reading through, your view doesn't seem tied to regenerating health, but rather to the difference between a slow advance with many mistakes tolerated, and a quick advance where few mistakes are tolerated. This issue rather seems to be about a larger scale of game design and the toolset the game gives you. | 18 | 40 |
[Doctor Who] Why didn't the Time War destroy the space-time continuum? | When the Doctor's TARDIS exploded it caused cracks in the fabric of the universe all across time and space. The Doctor's TARDIS is an obsolete Type 40. Gallifrey fought a war across time and space wherein hundreds if not thousands or more TARDIS' that were more powerful than the Doctor's were destroyed.
So, if one TARDIS going boom cause cracks across time and space why wasn't that damaged magnified a thousand and more fold by the casualties of the Time War? | Several possible explanations of varying plausibilities and speculativities:
- The Doctor's TARDIS may have been intentionally destroyed in a specific, time-rupturing manner that could not, in a normal combat situation, occur.
- The manner in which the Doctor's TARDIS was destroyed may have been easily preventable by another Time Lord with another TARDIS, so as long as there were multiple Time Lords around, such a cataclysm could have been prevented.
- Most TARDISes may have been far less important in the history of the universe. TARDISes don't necessarily exist in linear time (Sexy remembered future console rooms), so the destruction of a TARDIS could cause its whole history to come undone. The Doctor has saved the universe many times over, so destroying his TARDIS and undoing his good works could have torn history to shreds.
- As each TARDIS contains an aspect of the Eye of Harmony, which is said to regulate the Web of Time itself, the Doctor's TARDIS may have contained the only remaining aspect of the Eye in the entire universe. With the main Eye sequestered away with Gallifrey and no other TARDISes containing aspects of the Eye in existence, it is possible that the violent destruction of the only remaining aspect was enough to rupture the Web of Time itself. | 22 | 33 |
ELI5: What exactly am I paying domain registrars for? | If they don't do hosting and there is no way they have rights to every domain before it's purchased, what service are they providing and is it one that somebody could do without them? | There are some administrative that need to be paid for (staff, office costs, hosting their own website).
But mainly there needs to be some fee involved otherwise there's nothing stopping people from registering millions of domains, just for fun. | 14 | 30 |
Relevance of Freud today? | Not sure if i should be posting on the psychology forum or psychoanalysis etc. but ill start here. I was reading Laclau's On populist reason to understand more about floating signifiers. All was good for the first two chapters or so until he started descending into Freudian territory. My impression of academic Freudian theory is that it is used to understand how past theoretical thinkers utilize his theory, or to understand revised (better) versions of his. But it seems to me that he (among other thinkers such as zizek, lacan?) interprets and take his concepts such as the oedipus complex, identification etc. quite literally. I am not sure if it is worth delving into the whole corpus of Freud's text into order to understand Laclau (or Lacan etc. for that matter). I wonder what you guys think? | Freuds’s theories have impacted nearly every field in the humanities and are well worth reading. Having a strong basis in Freuds theories allows you to develop your understanding of the psyche and humanity by allowing you to enter the conversation. I’d highly recommend Ian Craib as well for an introduction to Psychoanalysis. | 23 | 19 |
By what methods do isolated ponds get fish in them? | There are a lot of isolated ponds out there with no connection to waterways. Like the ponds here and there on a farm, or the display ponds where I work. They all seem to have fish in them, usually little sunfish, none bigger than a few rare 6-7 inch specimens. How do these fish get to the ponds? I realize there's a variety of methods, probably things like stocking by humans or fish getting washed into a pond by floodwaters. Are there any more exotic or unusual methods? | Also migratory birds and waterfowl transfer amphibian and fish eggs. The eggs attach to the legs, down, feathers of the bird and are deposited (washed off) when the bird enters the next water source. | 100 | 218 |
ELI5: Why do many different animals all have white bellies? | It is primarily a form of defense from predators. A larger animal looking down on a smaller one would see the dark color of the preys back which would help camouflage it with the ground or whatever is underneath. A predator looking up at the white/ light colored underbelly would see it blending in with the sky.
Eg: think of the black and white of killer whales. Dark to hide it against the ocean floor from the top. White to hide it against the the sky from the bottom. | 24 | 28 |
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How does our sense of taste differ from other species? | I am not just asking about other mammals but even insects, or anything that can taste. Are there any animals that can't taste and just use smell? How about spiciness and sweetness?
PS. let me know if there is a better flair than the one I am using. | Different species are adapted to detect different chemical compounds, according to the foods they generally eat (and what compounds those food species evolved to produce to avoid being eaten.)
Cats purportedly do not taste 'sweet' things as such- they lack the receptors for it, as obligate carnivores with little need for detecting sugars or starches.
Capsaicin, the main(?) compound for spiciness, was developed specifically as a defense against being eaten by mammals, since our mastication and digestion renders pepper seeds unable to sprout, where avian digestive properties do not. Birds can taste this compound, but have no adverse reaction to it- so the relevance of this example depends whether you consider the burning part of peppers to be part of their flavor. | 384 | 577 |
Can human brains actually "multi-task" or is our brain just capable of swapping back and forth between tasks quickly? | When I'm brushing my teeth and doing something else at the same time with my other hand, like folding a pair of pants, I find myself involuntarily stopping brushing my teeth and only focus on the folding. I don't even realize I stopped brushing my teeth. What's the science behind this? | The brain has a multitude of interconnected systems and modules specialized for different tasks, and these operate in parallel at all times - so yes, to some degree, multitasking is possible. If you think about it, one part of your brain is processing visual information, another processing audio information, another keeping you breathing, etc etc etc, nonstop - so your brain is always doing many, many tasks at once.
Where this breaks down is if you want to do two tasks that use the *same parts* of the brain at once - this is something we can't really do. For instance, we can't typically split our conscious attention - we can switch it back and forth fairly quickly, and we can automate tasks through extended practice so they don't take much conscious attention (like driving) - but generally you won't be able to use those parts of your brain to do two things simultaneously, because in order for the brain to accomplish a given task, it has to inhibit any activity associated with other tasks to avoid crossed wires and failures. | 15 | 18 |
Why must therapeutic proteins be stored at 2-8°C to prevent them from degradation and denaturation when proteins in our body are in an environment that's 37°C and are perfectly fine? | What happens exactly with the stability of therapeutic proteins when kept at room temperature? | Proteins have various ordered and useful states and disordered and non useful states. Proteins which aren't frozen at room temperature will tend to loose activity over time. This happens in the body as well, but the body can replace broken enzymes.
They're also away from other useful proteins in cells that would keep them properly folded, so they'll tend to denature more quickly.
Proteases, chemical oxidation, and microbes tend to damage them over time, so cooling them slows these things down.
That said, in the lab enzymes have been left out for one reason or other for weeks and have been fine later when we tested it. It really depends on the enzyme. Some do less well in warm temperatures, some do better, depends on your luck. | 30 | 65 |
Is the net amount of energy of the universe zero? | I thought I remembered in A Brief History of Time that Stephen Hawking says something about the net energy of the universe being zero because gravity is a negative energy that cancels out the positive energy in the universe. I don't have the book now, but this came up in conversation with a friend, and I realized that I didn't have a very good grasp of this idea and its broader implications in cosmology. So my questions are 1) Am I characterizing this idea correctly? 2) How does this relate to the Big Bang and the origin of everything? | If 1) You calculate the Newtonian energy and 2) If the universe is *exactly* flat, then yes. However, condition 1 isn't really sensical because we should use general relativity to calculate the energy of the universe - but because the metric of spacetime isn't time translation invariant, you can't construct a globally conserved energy. Condition 2 is questionable, because the universe might just be "close to flat" rather than "exactly flat". | 17 | 24 |
[QWOP] What happened to that poor country that this is their best athlete? | Did they have a Polio epidemic or something? | The small country had a program similar to Make A Wish where this disabled athlete was allowed to compete in a small, token way in a single event.
There was an uproar among a small but very vocal and influential portion of the populace, believing this athlete would bring shame to the country and set them as the laughing stock of the world.
The remaining athletes all declined to compete, after the registration deadline had passed, and left this one Olympian as their sole representative.
At the competition itself, his competitors also bowed out, forfeiting their chance at an easy win to let QWOP, as he became affectionately known, to bring home his nation's first gold medal in their Olympic history.
It was a great show of solidarity in the face of discrimination.
QWOP was hailed as a hero of his homeland. The feel-good special they aired before the event covered most of this. It was a tear-jerker. You should try to find it on YouTube. | 123 | 122 |
Is a utopia possible or impossible? | A friend told me they believe it is possible to achieve a perfect society while I said it's nearly impossible (at least in this realm and reality).
I was thinking about how even some plants try to protect themselves from being eaten and how most living things are parasitic to each other. Suffering is inevitable here so I'm not sure how a utopia would work here.
I know humans created the concept of heaven but I'm not sure what that would look like realistically | As long as different people want different things, there will always be some sort of conflict, where people who want one thing, and people who want a slightly different thing, squabble over how best to allocate resources between those two projects. There can't be a situation where every single thing is good when there are any conflicts of interest.
However, there absolutely could be worlds with far less suffering than what humanity experiences now, just as the current world is a world with far less suffering than what humanity experienced several decades ago (and likely a far greater ratio of joy to suffering than existed centuries ago, probably at least back to the development of agriculture).
If we don't imagine a utopia as a world in which nothing is bad for anyone, but rather as a world in which the badness that exists is no more than what is necessary for other, greater goodnesses to exist, then it might not look much like how we initially imagine a utopia. This would be like Leibniz's "best of all possible worlds". He thought the actual world was in fact that best of all possible, but most contemporary philosophers think that a better world is possible. However, if there is a best possible one, then that one would be a utopia in this weaker sense - and it would, by definition, be possible. | 19 | 21 |
How truly accurate is carbon dating and how does it work? | Carbon dating is very accurate.
There are two kinds of carbon that occur in large amounts C-12 and C-14, C-14 decays. When a plant is alive it takes in carbon dioxide and uses that to make its structures, in this living plant we would find C-14 and C-12 in ratios very similar to those that occur in the air. When the plant dies it stops res pirating, thus no more C-12 or C-14 are put into the plant. The C-14 slowly decays (at a known and constant rate) into C-12, so as the dead plant matter goes on in time the C-14 becomes less than in the atmosphere and the C-12 becomes more until there is no more C-14. By taking a sample of old plant matter (wood for instance) and looking at its ratios of C-14 to C-12 you can get an accurate date for its age. | 25 | 63 |
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ELI5: Vitamins; what are they? How do they work? What processes in the body require them and how? | We're always being told certain things contain vitamins and that those are good for one's health, but what actually are they? What functions of the body require them, and how does it make use of them?
Bonus round: Antioxidants; another health food buzzword - what are they, and what do they do? | A "vitamin," generally, is any of a group of groups of molecules, each group of molecules constituting one vitamin. For example, there are eight compounds that constitute vitamin E.
What constitutes a vitamin is that it can't be something the body makes on its own: we must take it in through our diet.
Here are the thirteen such groups that our bodies require, along with a non-exhaustive list of what our bodies need them for:
1. Vitamin A (used in eyesight, skin maintenance, human development)
2. The B complex (1, 2, 3, 5, 6, 7, 9, and 12) (used in cell metabolism)
3. Vitamin C (Used in immune response)
4. Vitamin D (controls absorption of calcium, magnesium, and phosphate in our gut)
5. Vitamin E (we're not sure quite what it does, but it may have antioxidant functions, while I'll get to)
6. Vitamin K (blood clotting, bone formation, etc)
Our bodies use these compounds in various ways: reaction mediation, breaking them down to use their components, etc.
#Bonus Question:
Antioxidants. As the name implies, they inhibit a class of reactions called "oxidation reactions," which is the same reaction that forms rust. In the body, instead of rust, they create something called a "free radical." A radical in general is anything with a single unpaired electron. Because of that, they are highly reactive. "Free" radicals are uncontrolled by the body, and they can inflict damage to us. | 33 | 47 |
ELI5: how do taxes work for people whose source of income is coming in from many different countries, such as musicians | It depends on the country they reside within, the amount earned in foreign countries, and the specific laws of those countries. In most cases, they either allocate income (paying the income taxes where the money was earned and nowhere else), pay income taxes as if they earned the money within their resident country, or a combination thereof. More rarely, they allocate the income, pay the taxes of the country in which they earned the income, and then pay any resident taxes above the amount paid (so if resident country is 10%; foreign is only 5%; each country gets 5%). There are a few cases where they don't pay tax in either country. | 39 | 222 |
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Is it Unethical to be a Law Professor at a Very Low Ranked Law School? | My friends and I have recently been discussing whether it is ethical to be a law professor at a very low ranked law school. This quandary comes from two sources. First, these schools generally have absolutely atrocious employment prospects. As such, law professors are directly taking part in a system that saddles students with large quantities of debt while giving most of them no method of utilizing their law degree to pay off that debt upon graduation. Second, these schools have incredibly low admission standards in terms of grades and test scores, which are used as surrogates for assessing student ability. Thus, law professors are also directly involved with the bestowal of law degrees and the churning out of attorneys who likely shouldn't be practicing law and will not provide good or even adequate service to their clients. I believe these concerns apply to fields outside of law as well, but law school seems like a very good example through which to explore them. Would love to hear others' thoughts about this. | I think your ethical responsibility as such a Law professor is to actually make the best of the students you're given. Focus on maximally improving your teaching, and through that, make sure those future attorneys sitting in your class *do* achieve the minimum level required. There's always plenty of opportunity to improve your own quality of teaching.
Join the educational boards on your school, push for policies that improve the quality of education at the school, and you'll increase both the ranking and quality of alumni of your school. There's lots of ways professors can influence the quality of the school. Act in a way that you're not part of the problem, but actually make an effort towards solving those problems.
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Why does rough childhood makes some people strong while some mentally ill? | Are people just randomly born weak and strong?
*edit: strong is keeping one's sanity at full health despite possibly-traumatic events, weak is getting ptsd or other illnesses because of it* | Depends on Natural resilience, time span and onset of bad experiences (earlier and longer being worse), existence of a social support net or care taking alternative, the kind of instability (family, societal, emotional/financial/...).
In short: there are a lot of factors. | 95 | 60 |
ELI5:Infinity plus one | It really depends on what you mean by "infinity".
In the usual sense, we're talking about something called cardinality. This is how many things you have in a set of objects. Adding one more object to an infinite set of objects doesn't change how many there are. Neither does doubling the number of objects. A "cardinal" is an object that represents the size of something, and an infinite cardinal plus the cardinal one is the same infinite cardinal.
There's another sense of infinity called ordinality. Here, we're talking about numbers that have an order to them. In this case, infinity plus one is different than just infinity: you have a whole, infinite range of numbers, and then one number that comes after them, bigger than all of them. An ordinal is a number that represents the ordering of an object, not just "how many" are in it, so an infinite ordinal plus the ordinal one is different than the infinite ordinal alone.
Most of the people here seem to be giving amateur or naive answers, which isn't a good way to talk about infinity. The problem with "infinity" is that there are actually many mathematical contexts where it can appear, and how it works depends very, very heavily on the technical details.
(There are actually a few more intricate examples where "infinity" is a number, but those require some technical details to talk about.)
Edit: Placed sentences in the wrong spot in first edit. | 25 | 26 |
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ELI5: Why do police in America get away with so much unnecessary violence, even with video evidence? | For good or bad, most jurisdictions in the US give officers the ability to use quite a bit of force if they have a reason to believe that their lives or the lives of bystanders are in immediate danger.
Even if video evidence shows that there was no imminent danger, the officer's testimony that they *believed* themselves to be in danger (possible weapon, verbal threat, etc)can be enough to justify it, according to those rules. So even if the video shows that a perpetrator didn't have a gun, the cop saying "He reached into his pocket, like he was grabbing a gun" could be enough to protect him, in many cases.
This isn't always a bad thing, but has certainly been the cause of many very unnecessary tragedies in the past few years alone. | 21 | 20 |
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ELI5 The Standard Model of particle physics | Quarks, Leptons, Bosons, what the hell does that all mean? | There are four forces of nature. You've all probably heard of electromagnetism. There are two more which are less know but just as important. The strong force holds every nucleus together and the weak force is responsible for radioactivity. The bosons are the carriers of these four forces. You have photons for electromagnetism, gluons for the strong force and the W and Z bosons for the weak force. Gravity is an outsider and doesn't have a boson for as far as we know.
The quarks are the buildingblocks of protons and neutrons. Those quarks are held together by the strong force. Leptons are a bit rarer and less known. The most common lepton is the electron and revolves around a nucleus. The force that keeps the electrons around the nucleus is electromagnetism. After all, the electrons are negativly charged and the protons in the nucleus positive.
I hope this clears things up a bit, but this explanation is far from complete. If you have any questions still, don't be afraid to ask. | 10 | 35 |
Why can't the immune system create antibodies that target the rabies virus? | Rabies lyssavirus is practically 100% fatal. What is it about the virus that causes it to have such a drastic effect on the body, yet not be targeted by the immune system? Is it possible for other viruses to have this feature? | Our body can make antibodies against rabies, and the antibodies are effective against the virus, but the problem is what stage of infection you are in what immune status.
Rabies infect neurons and then it travels up to the brain. When the virus ends up inside of a neuron, it can be difficult for antibodies to detect it. If the virus ends up in the brain, your likelihood to survive is very very low. Luckily, rabies takes time to infect neurons, so there is this window that a post-exposure vaccine will quite likely to save your life
Basically, if you are in a country with rabies issue, get vaccinated. If you get bitten by some animal, ask a doctor to see if you need a rabies vaccine | 2,993 | 3,734 |
ELI5: Why do your muscles get so sore when you have the flu?? | One task of white blood cells is to repair and rebuild muscle fibres which are damaged from day to day. However, when you have the flu, your immune system diverts the white blood cells from this function to fight off the flu virus, thus leaving your muscles and joints feeling sore and achy.
In addition, white blood cells produce a chemical called cytokines when fighting the infection. This causes inflammation in muscles and joints, resulting in pain. | 130 | 114 |
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What type of radiation does lead shielding stop? | As far as I'm aware there are only three types of ionising radiation - alpha, beta and gamma. Since alpha particles can be stopped by any sort of barrier, I'm most interested in beta and gamma radiation. Is lead shielding only able to stop one or both types?
In addition, do different types of shielding perform differently against different types of radiation. e.g. Would Osmium or Iridium work better/worse?
If I've made some glaring omission or have misunderstood something, please let me know. | > there are only three types of ionising radiation - alpha, beta and gamma.
That’s not true.
Lead will shield any of the three types of radiation you mentioned. Although alphas are easy to shield with anything, so you don’t really need lead. Betas can be shielded with lead, but high-Z materials cause betas to emit a lot of bremsstrahlung as they slow down, so for betas you usually something with low Z to slow down the betas, followed by something with high Z to absorb any bremsstrahlung. If the shield is just lead with nothing else, it’s probably for shielding x-rays/gamma rays.
To shield x-rays and gamma rays, you want a material with high Z. People will often think lead is chosen for its density, but actually the Z is what’s more important. Attenuation of photons is proportional to exp[-kz], where z is the depth into the shielding and k is proportional to the density and the total cross section for removal of a photon. So the factor k is linearly proportional to the density, but the cross section is usually some combination of power laws in Z, like Z^(2) or Z^(3). So the dependence on Z is much stronger than the dependence on density. (However the cross sections also vary with energy.)
So other high-Z materials would work too. Depending on what material it is, and what the expected photon energy is, the thickness of shielding might need to change a little, but they will all work. | 61 | 34 |
Why does string theory treat time as a separate dimension? | I thought time and space were interwoven into spacetime, where both space and time were relative, and can be bent/stretched.
But every time I read about string theory, I keep reading that there are 3 observable spatial dimensions, 1 time dimension, then 7 very tiny spatial dimensions that we cannot see.
But why is time separate? I thought Einstein proved time and space were combined. Does time need to be separate for string theory to work? | Even in relativity, time is different -- in ordinary relativity there are 3 spatial dimensions and 1 time dimension. This shows up in the way you calculate distances in spacetime. Whereas in ordinary space, you calculate distances by
d^(2) = (x_2 - x_1)^2 + (y_2 - y_1)^2 + (z_2 - z_1)^2
in relativity, we have an interval in spacetime defined by
s^(2) = -(t_2-t_1)^2 + (x_2 - x_1)^2 + (y_2 - y_1)^2 + (z_2 - z_1)^2
Notice the minus sign in front of the time term, the opposite sign from what you find for the x, y, z terms.
This opposite sign is what makes time different.
So in relativity, we have 3 spatial dimensions and 1 time dimension. In string theory, there are additional tiny spatial dimensions.
Relativity does tell us that space and time mix together into spacetime. In special relativity, two different observers will measure the same value for the spacetime interval s^(2) defined above, but how much of that comes from the spatial part and how much from the time part will differ.
| 79 | 259 |
How can we keep a human employed in the future when robots can do everything for cheaper? | I figure that if robots/automations become cheaper than paying for human workers, then why hire people at all? Also, you don’t have to worry about things like liability in high risk jobs. What are robots going to do to the job market? What will keep humans from becoming completely reliant on them? I see obvious potential for computer science/engineering/robotics jobs, but it seems like we are on our way to letting robots take the wheel so humans don’t have to lift a finger. | There are a few basic scenarios:
- Post-scarcity economy: As pointed out before, robots do all of the work. Everything beyond what is needed to live is strictly optional. Economics will consist of things which are artificially scarce (intellectual property), innately scarce beyond the need for labor (front seats at a concert), or produced purely to say a human produced it (art, handmade tools, organic produce). Jobs will consist of computer scientists and roboticists creating new robots, performance art, producing things by hand because people will pay for that, etc. Everyone will be able to live the lifestyle of what we consider today to be the idle rich, similar to how the modern-day welfare recipient still lives better than most kings did a thousand years ago.
- Mass die-off: Suppose the oligarchs in control of existing wealth decide they don't want to provide the fruits of their robots labor for free. Huge swathes of the population can no longer gain useful employment because there's no demand for their skills. The wealthy have no obligation to employ these people, and don't even need them to exist. Either Charity, family support, and existing public institutions allow them to exist until they die, or they starve to death in the streets.
- Revolution\Militarization: People don't like the idea of dying in the streets, especially when roboticization means they don't have to. They violently oppose the policies of the wealthy, and take control of the means of production. Down with the Bourgeoisie, up with the proletariat, revolution! Revolution!
| 31 | 20 |
ELI5: Why are European curbs 3-5 centimeters tall (and don't destroy tires) while American curbs are 6 inches (15 centimeters) tall and shred tire sidewalls. | American curbs are there to protect pedestrians, protect drivers from driving off the road, protect landscaping beyond the curb, to retain and direct storm water in the road. The height is just easier to use in a design phase due to it being 0.50 feet rather than 0.33.
Curbs 3-5 centimeters are tripping hazards, not ADA compliant and serve little purpose from a storm water standpoint. | 101 | 113 |
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Skin cells constantly regenerate. So how/why is it possible to have scars? | The process of wound healing involves more than just the replication of epithelial (skin) cells. Skin is composed of both epithelial cells and an extracellular, collagen-containing, connective tissue that is laid down in a meshwork pattern when skin develops naturally. In a wound, both the cellular and connective tissue components must be regenerated.
Scars form primarily due to the regeneration of the connective tissue. The first reason for this is that the body relies more on the regeneration of connective tissue rather than cells to fill in the hole left by the wound. This is because it is quicker to synthesize a lot of collagen than it is replicate a lot of cells. This makes the healed region more fibrous than cellular. In fact, in larger scars, the central regions may be entirely connective tissue, devoid of actual epithelial cells. Second, unlike your pre-wound connective tissue which is arranged in a meshwork, the collagen in a healing wound is laid down in a single orientation which leads to the tougher feeling, but ultimately weaker scarred tissue. | 14 | 17 |
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Is there a proper study on how much race affects income when properly adjusted? | When I look for these kind of stats all i get is "x group makes more than y group"
I want to know what happens when you account for education, social status, personality, life choices and location. Do the differences disappear or maximize or stay the same? | If you’re interested in the marginal effect of being black vs white on income, controlling for education will not give you an accurate estimate. The issue is that race also has an effect on educational attainment. By controlling for education, you are ignoring that black Americans have lower incomes in part because they have worse educational opportunities. | 45 | 27 |
Why can we see clearly underwater with goggles but not with our bare eyes? | Also, do fish have some sort of eye-covering membrane or how do they circumvent this problem? | Your eyes are trained to deal with a surrounding medium with a low refractive index, like air. Water has a high refractive index, which makes the light bend in ways your eyes aren't expecting.
Fish eyes are made for seeing while immersed in water, so they'd have the same problem in air that we do in water. | 153 | 150 |
How exactly does a bank account work? | I'm only 14 and I don't have a bank account. | You give your bank your money. They put it in the vault and keep track of how much they have from you.
They will from time to time lend your money to other people for mortgages or student loans. Because they can use your money for other things, they will pay you a small percentage on a monthly basis. This is called interest.
At any time you can go to the bank and ask for some of your money (making a Withdrawal) or give them more money (making a Deposit.)
People keep money in banks because it's secure, it's more convenient than carrying a lot of cash, and once you get a job, you can get your employer to put your salary directly in the bank account so that you don't have to cash a cheque every two weeks. | 35 | 47 |
ELI5 So everyone is talking about this year's US inflation, can anyone explain why it's so important? | Inflation, broadly, is what happens when money becomes less valuable as a result of more money being injected into a given economic system. In this case, spending went down during the pandemic, and a lot of stimulus money wasn't actually used. Now that the country is reopening, a lot of people are starting to spend that saved-up cash.
The current inflation is both a good and a bad sign; it's bad because it obviously means prices will go up on essentially everything, but it's a good sign because it indicates that a lot of people are starting to spend money again at pre-pandemic rates, indicating that the US is returning to economic normality. At the same time (on a personal level); inflation is actually a *good* thing for debtors, as debts don't inflate with the currency, thus the functional value of the money you owe goes down with inflation. | 46 | 29 |
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How to engage with people doing similar research to yourself? | Whenever I meet someone doing very similar research to what I'm doing, I don't know how to act. A part of me feels really excited to find someone interested in the same topic, and begin day dreaming about asking them to co-author something. But the other part of me feels incredibly stressed at the thought that someone else is working on research that is (sometimes very) close to my own. I'm a PhD student, so I feel particularly threatened if I meet someone more senior in this category.
How much do you share in these situations? How do you go about things? | The main point that you want to communicate in this situation is that you are interested in knowing more about their work. Try not to think about issues like future collaboration, etc. because the first step is to build a connection around your shared interest, and that takes time. If you just give someone a chance to talk about their work they will often be happy to share. Hopefully they will ask about your work in return. | 21 | 33 |
ELI5:US Supreme Court: King v. Burwell. Obamacare subsidies | In light of the recent ruling on King v. Burwell (in favor of the Government, 6-3) and the number of questions it's already creating we decided to make this sticky thread. Feel free to ask any questions related to this ruling in this post or offer an explanation of the ruling and the background behind it. | "Obamacare" made health insurance exchanges. Each state had the option of making their own exchange, or using the federal exchange.
The part of the law in question gives federal money to people who are within 100% to 400% of the federal poverty line.
However, the law technically says the federal money can go to people who buy insurance from an exchange created "by the state" not "by the state, or by the federal government."
In the background of all of this, there is the fact that WAY more states refused to make their own exchanges, and used the federal exchange than Congress expected, because of negative reaction to the law.
So there are LOTS of people who got the federal money for insurance bought on the federal exchange.
If the "by the state" language meant just "by the state" the whole insurance scheme would fall apart, because there are so many people who rely on the subsidies and the federal exchanges.
However, the Supreme Court just decided that "by the state" actually meant "by the state or the federal government," essentially because the law would not work without that interpretation.
So people get to keep their federal subsidies now, regardless of whether they bought their insurance on the federal or state exchanges. | 82 | 221 |
[Pokemon] Questions about levels. | Levels in their entirety dumbfound me.
* What is a level?
* How are they gauged without a pokedex, or before they even existed?
* Why is their a level cap?
* If levels are a means to evolution, how come I can find pokemon in the wild with a lower level, than needed for the evolution of the unevolved version. Kakuna and Beedrill as an example.
I feel like I'm forgetting some questions, but I'll just put this up for now and edit in any more I have, if you have any questions please post them, and I'll add it to the list, just so we can get levels entirely understood. | A level is an subjective measurement of the pokemon's experience and motivation. Higher level pokemon are more experienced and apply themselves harder.
Everybody plateaus sooner or later. You can only push yourself or others so hard.
Evolutions are optional. You can actually startle your pet pokemon out of evolving by scaring them with B when evolution occurs. Some pokemon stop learning after they've evolved into their final form, it's not always the smartest or best thing to do. | 29 | 52 |
Why do we have 2 of some organs but only 1 of others? | Because sometimes we only need the one (reproductive organs, mouths, anuses), and sometimes we need two for redundancy (kidneys, lungs, arms)
As organisms evolved, the most advantageous adaptations survived. So, if only having one kidney or having four stomachs was better, we would have likely eventually evolved to have them. | 35 | 70 |
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Writing an engineering paper but I feel like it does not have any novelties | Presently I am writing on paper/journal that describes how I implement a theoretical model of some engineering concept into stuff that operates in the real world. It is my first academic paper btw.
The thing is, everything that I do in this paper, someone else already did with better and more optimized results. By no means have I copied their methodologies, it is just stuff that I do that has become common knowledge for everyone in the field. Therefore nothing new, like a journal on how to turn a bread recipe into a real edible bread with some notes on how others can do it.
I tried to communicate with my supervisor, I think he understood it yet feigned ignorance and told me just to keep on writing. Maybe he is right, after all, I'm a newbie in the academic world.
Has anyone had a similar experience? I wrote this post since I worried that this journal would not pass reviews. | Not every publication needs to be groundbreaking; work that bridges smaller gaps in our knowledge is valuable too. Can you identify any smaller gaps in the primary literature that your paper fills? For example, are you putting the model into practice in a situation not covered in prior research? If previously published methods are preferable in most cases, can you identify a specific case or cases where your method might be preferable? Would your solution be of interest to someone if they were trying to optimize the implementation for time, cost, availability of resources, a specific performance factor, or etc.? | 53 | 64 |
AskScience AMA: I'm Vinny Lynch, assistant prof. of human genetics at UChicago. I led one of two research groups that independently found why elephants don’t get cancer as frequently as we thought they should (Spoiler: 20 copies of the p53 tumor suppressor gene). AMA! | Hi, I’m [Vinny Lynch](http://lynchlab.uchicago.edu/index.html), assistant professor in the Department of Human Genetics at the University of Chicago.
A while back, I got interested in Peto’s Paradox: the observation that big and long-lived organisms like elephants and whales don’t get cancer as often as we think they should. If all cells have a similar risk of developing cancer, then really large animals should be at really high risk.
But there’s absolutely no correlation between body size or lifespan and cancer rates.
So we studied elephant genomes, and now we think we’ve found the mechanism that explains the paradox. Elephants have 20 copies of the very well-known p53 tumor suppressor gene (to be precise: one p53 gene and 19 p53 retrogenes).
We looked in 60+ other animals, including whales, fish, birds, and humans, but found that only elephants (and maybe bats) have more than one p53 gene. We looked in woolly mammoth and mastodon genomes as well, and shed some light onto the evolutionary origins of p53 expansion (if you’re curious about mammoth genomes I did [another AMA](https://www.reddit.com/r/science/comments/3csgs6/science_ama_series_im_vinny_lynch_geneticist_at/) a few months ago). Lastly, we transferred one of the extra p53 genes from elephants into mouse cells that we grew in the lab and made some pretty interesting observations.
We released our findings on the [open-access preprint server BioRxiv](http://biorxiv.org/content/early/2015/10/06/028522), and another group, which came to pretty much the same conclusion but focused mostly only on elephants and humans, independently released theirs in [JAMA](http://jama.jamanetwork.com/article.aspx?articleid=2456041). You can read an article about [our two studies in the New York Times](http://www.nytimes.com/2015/10/13/science/why-elephants-get-less-cancer.html).
Edit: Well, it’s been a lot of fun but I have to run. Thanks for all the questions Reddit!
| Hi Vinny,
Does your work have a therapeutic end goal or is it just basic research?
Is P53's mode of action well understood?
What do you think of the potential for CRISPR and related technologies for treating cancer by selectively targeting sequences of DNA, if that's not too far outside the scope of your work? | 121 | 3,500 |
ELI5: Why are so many 7/11s and Dunkin Donuts owned and staffed by Indians? | Not sure if it's a regional thing but I noticed it locally and when driving in nearby states as well | When immigrants come to the USA and are looking to start a new business they often go to the US department of labor and ask about trending industries and see what areas are projected to be a growth market.
When for political reasons or whatever you get a large spike of immigrants from a specific country. They then all show up at the same time and all of them ask what business are trending and they all get the same answer.
So now you have a large population from a specific region all working the same type of business. After a while new immigrants come over and they want to find work, if they are lucky enough a cousin or something came over before them and is now a business owner. So they go work with their family members. The first immigrant who opened the business now has a bunch of family members working for them and might want to expand. Maybe try and get a store for their son or nephew to run for themselves.
Once you already have a successful franchise with a company you can get a large cut on the franchise fees for opening up a second location compared to opening up the first. Also you have been doing this for a while so you now know what works and what doesn't and can improve your chances for the second branch being successful. | 95 | 73 |
On a cellular level, where does lotion go when you rub it in? | I wasn't able to find a lot of info on this. Best answer I could find is the lotion molecules move in between the skin cells. It didn't tell me how far they penetrate though or if our skin would just absorb lotion if it was left alone on our skin. | Most lotions are just emulsions of oil and water, and the skin the water and oil molecules do not actually penetrate very far, unless of course the skin is broken. The lotion will just saturate the stratum corneum which is the topmost layer of the skin made of casts of dead keratinocytes. The reason why lotion can make skin look less "ashy" is because by saturating and hydrating the stratum corneum, it makes it more transparent. | 24 | 28 |
"Evolution is entirely too slow..." | Background: Stumped during a friendly debate on creation vs evolution. I'll let the post speak for itself:
>Perhaps the biggest problem of all--evolution is entirely too slow. I've been putting together this table to compare rates of evolution among various species, both observed and assumed, using the emergence of proteins of novel function (through fusions, duplications, de novo from junk DNA, or without any homologs at all) as well as protein binding sites as a benchmark, compared with the number of mutation and selection events needed to find and fixate them. I'm not alone in realizing this, it's an extension of several arguments that biochemist Michael Behe put forward in the book, Edge of Evolution. [Sources](http://justpaste.it/17oi) for these numbers.
Species:|e coli|HIV|Malaria|Homo
:---|:---|:---|:---|:---
**Population:**|6 * 10^10 in the LTEE|10^20 per last few decades|10^22 per last century|10^12 since chimp divergence
**Mutation Events:**|3 * 10^11|3 * 10^19|2 * 10^19|6 * 10^12
**Evolution:**|no new proteins or binding sites, no gain of FCT, only modification and loss|a duplicated protein and a new binding site|0 new binding sites, few if any proteins of new function?|280 to 1400 new genes of novel function, many arising from non-coding DNA, likely just as many new binding sites. A large number without homologs?
>Humans have had a million times fewer mutation events than HIV and maliara have had in the past several decades, yet have produced over a thousand times more. Other microbes show similar rates. Using this benchmark, that means hominids would have to evolve a billion times faster than these other species in order to produce humans in 6m years. What could account for this difference?
| Firstly, there is a lot of confusion here over what defines a mutation.
For isntance, there seems to be the idea here that new genes ALWAYS evolve when new mutations evolve.
>Humans have had a million times fewer mutation events than HIV and maliara have had in the past several decades, yet have produced over a thousand times more
What is that ? humans have more mutations than they have ? Or is it that you are looking at just novel genes.
This makes the assumption that mutations HAVE to ALWAYS lea to new genes forming. But this is not the case, because evolution relies on selective pressures for these genes to evolve.
For instance, the LTEE experiment, the mutation rate would be slower than in the wild, because of the effects of stabilising selection in that experiment. Mutations would be less favoured, because they were kept in the exact SAME environment for years. The evolution of new genes and functions occurs in response to the environment.
In the same time as this experiment was ongoing, various strains of bacteria developed in the wild, with resistance to antibiotics. Strains like NDM-1 which evolved new genes over the last few years. Genes for antibiotic resistance.
HIV is highly genetically variable, but it doesn't add many genes, because it can only hol 10,000 base pairs, which equates to around 9 genes. Claiming that it doesn't evolve as much because it hasn't acquired 280 genes is an absurdity. Especially considering that HIV can evolve resistance to antivirals within the course of one infection, so fast is it's evolution.
Humans are also the only diploid organisms here. So the replication and gene duplication in humans is favoured over bacteria. Human genes can mutate and diversify, and become junk, and they can tolerate large numbers of genes being added.
The BIG assumption here is that evolution only happens through adding new genes. But this is patently false. Changes in genes are just as, if not more important rivers of evolution. SIV, and most other related viruses have the same numbers of genes, but they have been adapted to do different things. | 16 | 18 |
Does the probabilistic nature of quantum mechanics extend to non-quantum phenomena? | My understanding of this topic is very basic, but from what I can gather, everything (?) at a quantum level is described in a probabilistic sense rather than a deterministic one. Not because of measurement error, but for more fundamental reasons.
My question is this: does the uncertainty we observe in quantum mechanics manifest in any way in non-quantum phenomena? Are phenomena at a non-quantum level deterministic, as far as we can tell? | What happens as things go from one to a few to many particles is that the total uncertainty for the system goes down relative to anything you would want to measure. So, simplistically speaking, the total amount of momentum could go up with the total number of particles, while the uncertainty of the momentum goes up much more slowly. By the time you get to macroscopic sizes, in the hundred of trillions of particles and more, the uncertainly due to quantum effects is smaller than the error of any measurement you could make. So for all practical purposes these things are deterministic with respect to quantum uncertainty. However, there are other things that determine uncertainty, such as an inability to accurately model large systems due to an inability to get all the details correct, hence the uncertainty in weather forecasting. | 14 | 15 |
CMV: Designer babies aren't inherently unethical | That is, if they were designed to get rid of diseases, deficiencies and disabilities along with the technology being universally available for use.
I don't understand what other issue there might be with them if no one is getting an unfair advantage. If these two conditions are met, no one is giving deliberate advantages to the baby and the wealthy wouldn't be the only ones getting healthy, inherited disease free babies.
I don't understand where the issue is with a future with no disabilities or genetic diseases. | To start with, they are not inherently unethical. The idea could be used to do a lot of good. But that's going to have to come with limits.
The supposition that they would be equally available is simply wrong, however, and will be forever. There will be those that can afford to have their cake and eat it on the genetic level, and those who can afford to have a baby. Even a universal healthcare system is not going to mess around doing some of the things that designer babies may actually be able to be in future.
If genetics could be manipulated so that they were smarter and stronger and maybe even bigger than the rest of us, then you would be creating a master race of rich people's babies.
Also, as pointed out, we're not completely sure what we're doing. It's possible that in eliminating some diseases, we might also produce a vulnerability to other diseases. In a few human beings, that's going to be a bummer for them, but it will sort itself out. If it's everyone, then everyone could die.
I think it was said that the Spanish gave the native Americans such deadly diseases that between them arriving, and the British setting up their colonies in the US, 90% of the population had died. Imagine trying to produce some kind of society with 10% of the people.
Also, we find the gay gene. What do we do? Gay people aren't inherently suffering from their sexuality. But if we knew that we could set them up to be "normal", what then?
I think there are lots of qualities in people that we would try to edit out, and actually, it may not benefit us. Some of the world's smartest people are autistic. But for the vast majority of people, autism is considered a hideous mental issue, and would be edited out on birth.
| 28 | 66 |
[Star Wars] If Aanakin lived at the end of RotJ, re-embraced the light side of the Force, and had access to any technology, how well could his body be healed? | Improvements would more or less just be incremental. The SW universe doesn't have the tech to do things like clone and force-grow replacement parts on a casual level, so cybernetics is still the way to go. The state of the art has advanced from the Clone Wars days, as seen in the sort of casual/transhumanist cyber-enhancement going on out in Hutt Space in the Book of Boba Fett, so swapping out the old limbs for some cutting edge fingers and toes could give him some lighter, more agile and more comfortable extremities.
In terms of the lung situation, Fennec Shand shows that it is physically possible to put replacement internal parts in a human, so Vader could potentially ditch the rebreather in preference for cyborg lungs. He'd still be dependent on tech to breath, but he could potentially ditch the suit.
His burnt-ass face is still going to be a burnt-ass face. But since folks don't know his burnt-ass face on sight, going with cyberlungs and ditching the helmet would let him go incognito quite easily.
In terms of performance, it probably won't be much of an upgrade since Vader was more or less riding the cutting edge of military grade tech, but a set of cyberparts designed by someone not willfully being a dick are probably going to be a lot more comfortable. | 60 | 58 |
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Why doesn’t Mississippi look like Beijing? | I know this sounds like a dumb question(and it probably is) but hear out my rationale for asking:
Apparently the nominal gdp per capita of Beijing is about 24,000 USD and the GDP PPP per capita is about 39,000 USD and, while this is significantly higher than the GDP PPP per capita of the rest of the country, it’s on par with the GDP of Mississippi which is also about 39,000 USD.
I guess my question is, if Beijing’s GDP per capita adjusted to purchasing power is about the same as the nominal GDP of Mississippi, then why does Beijing look so much more industrialized?
Edit: I also want to add that Beijing has an HDI of 0.904 while Mississippi has an HDI of 0.871 to show that I’m not solely relying on subjective, qualitative metrics | Two countries can have the same level of wealth and have very different levels of industrialization. In fact, an economy can have almost no secondary industry and still be very wealthy. Think of the Cayman Islands with its financial services industry, or Macau with gambling.
Separately, a place doesn't need to "look" industrialized to be industrialized. Taiwan's Hsinchu Science Park may look suburban. On the outside, the buildings don't look too different from a mall or warehouse, but they house some of the world's most advanced semiconductor factories. Macau and Hong Kong are packed with skyscrapers but have little manufacturing. | 50 | 39 |
ELI5: An economics question: Why are some prices on products so volatile and "strange", like $5.21, $4.77, and $2.93 | For highly-competitive, low-margin products like staple foods at grocery stores, the stores have a set margin (price markup) from the basic cost. Let's say it's 2%.
If eggs cost them $1 to buy, they will sell it for $1.02. What if the egg shortage happens, and farmers have less supply, so they raise their price to $1.50? The grocery store will now price them at $1.53.
When you see "round" prices like $1.99, it's because they're able to be more flexible with the pricing. On low-margin, highly competitive foods, though, they're basically trying to keep the price as low as possible, even if it means a weird looking price. | 12 | 15 |
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ELI5: Why can we see through clear objects like glass even though they are solid, same for water and air? Why don't the atoms block light like they do in wood? | Same goes for water or air. | When a light ray with a given energy (wavelength) hits an object, one of three things can happen:
* the light is reflected back opposite from where it came
* the light is absorbed
* the light passes through unimpeded, but bent a little
The material being hit by the light is made up of atoms. Picture the atoms as little nuclei with electrons buzzing around them. These electrons want to jump further away from their nucleus to a higher-energy orbit, and they need to use the light to make this jump. But the catch is that they need very specific amounts of energy to do so. Think of using electricity to power an elevator in a building-- you either could use 60W to make the elevator go to the 2nd floor, or 120W to make it go to the 3rd floor. There are no in-betweens.
The atoms in glass have electrons that need higher specific amounts of energy to make the jump than visible light can provide. They have no use for that light, so it's free to pass through. The atoms in wood have electrons that DO need the specific amount of energy that visible light can provide, so that light is absorbed and the electrons can jump.
There is so much more to the story than this, but it's a good place to start. | 14 | 38 |
ELI5: Why do art museums only ever display a tiny fraction of the items they own? | As I understand it, a typical big-city museum has at most 5 or 10% of it's total collection on display at any given time. Some items will be rotated in and out but lots are permanent fixtures, meaning many (if not most) of the items in their possession will never be seen by even a single museum visitor, including works by acknowledged masters.
Couldn't a museum sell a substantial number of items to other museums (or to private collectors) and reap a substantial windfall? And wouldn't smaller museums benefit tremendously from acquiring lesser-known undisplayed works by major artists that are currently gathering dust in the basements of the biggest museums? | 1) Light can be damaging to many things. This can be limited with special displays but it is expensive.
2) Air can be damaging to many things. Like the light issues special displays can be used but they are expensive.
3) Space. Most museums do not have the space to display everything.
4) Quality. Not everything is of display quality, but is still of historic or scientific importance.
And museums do sell/share with each other a lot. But how, when, and to whom a museum is allowed to sell things is fairly highly regulated. They are not generally allowed to sell to private citizens. | 21 | 23 |
How to write a recommendation letter for a former professor of mine? | So, a professor that taught me during my undergrad years is up for a tenure track position, and I've just received an email from the committee requesting a recommendation letter.
This professor made a large impact on my intellectual development and I have nothing but good things to say about her. So, I want to write the best letter possible.
What things should I include in my letter?
Thanks in advance. | - context for knowing one another
- what set her apart
- why she was so important to your intellectual growth
- discussion of the particulars of her style that you think are special
- discussion of your personal achievement or success that can be linked to her influence | 16 | 19 |
Why do bananas and other fruit rot so much faster when they are in an enclosed space with one another? | Ethylene is a fruit hormone that is naturally produced by fruits. When green bananas are kept in a brown paper bag, they will ripen faster!
Rotting would be related to the concentration of ethylene in the surrounding gas. Also bacteria that causes rotting can easily proliferate to other fruits when they are kept closer together. | 28 | 34 |
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CMV: Crying it out is cruel and inhumane. | I am aware this is an extremely divisive subject among parents and that ultimately parenting style is individualized to accommodate the parents and the child's needs.
I am also aware of the breadth of research out there supporting both sides of the argument. What I have learned, though, is that research, in all fields, is highly influenced by the desired outcome and that the design of research can lean in such a way to support a hypothesis, especially when it is difficult to prove causation with so many confounding factors.
My view on crying it out: It is unlike any other approach human beings take on human interaction and human development. The argument supporting it states that the child needs to learn to soothe themselves to sleep, and ultimately it benefits them to sleep without waking through the night. However, in no other time in a child's development is the approach to teaching them how to acquire a particular skill or habit, simply letting them cry it out. What ever the objective may be, a parent usually guides a child by showing, talking through and repeating the habit or skill to be acquired. For example, when learning to ride a bike or prevent the development of a bad habit, such as hitting or biting, a child is shown the way through guidance and support. Also, in regards to sleeping through the night - more awareness on this subject is revealing the fact that humans are not designed to sleep a consolidated 8 hours through the night, but instead this is an adaptation to industrialization and modern work demands. As such, we have coerced ourselves to a sleep in a way that has be to be learned. Why is it that when our children are learning to sleep, some recommend letting them figure out this habit on their own? If this method is appropriate during the night, why is it not appropriate during the day when acquiring other habits? My opinion is that this argument is one of convenience to parents who choose this method, to justify the unrelenting crying of a child as they learn a new habit. In no other aspect of human interaction do we allow a fellow human being to suffer uncontrollably without intervention, sometimes to the point of emesis. In fact, in modern day society, we strive to prevent unhappiness and distress with psychology, psychiatry and pharmaceutical intervention because we have learned that without it, there is great consequence to the individual suffering and potential to society as well.
Apologies if I offend some parents, but I would like to understand how crying it out is not deleterious in the minds of parents.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | >However, in no other time in a child's development is the approach to teaching them how to acquire a particular skill or habit, simply letting them cry it out. What ever the objective may be, a parent usually guides a child by showing, talking through and repeating the habit or skill to be acquired
That's not accurate. You do show, talk though, and repeat - sure. But you also let the child work through problems themselves. If you're teaching a kid how to build with blocks, you cannot keep making the towers for them. At some point you need to encourage them to make towers themselves, screw up themselves, and learn from their own mistakes. A parent cannot always be a helicopter parent - children need to be self-reliant as well. That process will require the child to make mistakes, cry for their parent to fix it, and be told to fix it themself.
The same is true for sleeping. Yes, you show the child how to sleep, help them, and repeat the habit. But at some point you also need to let the child learn how to get themself to sleep. That process will involve some crying, yes. But it's a necessary skill.
| 64 | 61 |
ELI5: How do barcodes and their scanners work? Is there a global catalog of every barcode ever? Are no two alike? How does the scanner read the lines? | The black lines of the barcode absorb light which is read and translated into bits of imformation. the thickness and order of these lines represent a number. That number is filed through a database to find a matching one. When a match is read, any needed information is pulled to whatever use it is for.
There are tons that are alike, but they generally belong to one of a few different standards. Everything is organized by type of product, and then various specialized types of categorizations. Each set of standards uses each digit and different number of digits for various reasons and it is all about how the standard making organization decides to use it. Companies and manufacturers adopt certain standards for the barcodes and then they use it when they place it on a product.
Currently the most popular and accepted standard is maintained by ISO (International Standards for Organization) who manage many many many standards from the definition of a meter, a second, how thick lines should be on a blueprint, paper size, barcodes, etc.
| 26 | 57 |
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ELI5: Why do musicians that play in an orchestra have to use sheet music to assist them when other musicians that play other genres of music such as pop and rock etc don’t? | Length of material, complexity of their part, precision required from each section, specific methodology for learning to perform...just to name a few.
Besides, it’s not always the case that ensemble and orchestral musicians are reading. | 33 | 15 |
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Why does it seem that students who have a science background or are more science-minded tend to do quite well in arts subjects but not vice versa? | I was not getting any luck in getting an answer in r/NoStupidQuestions so I thought this would be relevant here
I'm currently both a science and arts student and I have noticed this to be quite true in most cases. Arts student will complain about struggling through a math or science requirement, while science students in arts classes tend to fair better
I noticed that institutions think this is the case as well as I also noticed that universities will have courses such as "calculus for the social sciences" or "biology for the arts" which is known to be less rigorous than the main calculus/biology class. On the other hand, I don't commonly see them offer "philosophy for the sciences" or "sociology for engineers". If science students wish to take arts classes, they are expected to enroll in the main class | I think part of it is the prerequisite knowledge. For an introductory college humanities class, you need to be able to read, write, and think critically. For even a remedial math class, you need all of the above plus all the math you’ve learned up to that point. Someone who is good at math already has the skills to do well in other fields. They just have to learn domain-specific information.
Regardless of your major, everyone will show up to an intro philosophy class with almost no philosophy background. You can’t show up to a calculus class with good critical thinking skills and no math knowledge expecting it to go well.
The cumulative nature of math also explains the existence of courses like “calculus for social sciences”. A standard calculus track is teaching you some math you’ll use in your field but also preparing you for more math which is usually the hardest part. If someone doesn’t need more math, they’re better off just learning what they’ll actually need. | 220 | 240 |
Is there any known correlation between a person's average body temperature and their susceptibility to disease? | For example, do we know if someone who normally sits at 96°F would have a different chance of getting sick than someone usually at 99°F? I know there are many factors that go into immunity, I was just wondering if someone's natural body temp has something to do with it? | Simply put, pathogenic species for humans tend to thrive on the lower end of human body temperature. At higher temps, pathways needed for homeostasis become unstable for small organisms like pathogens, stamping out infections. That's why sick people tend to develop fevers. At too high of a temp tho, the body itself cannot regulate homeostasis, and weakens, which can lead to issues that increase susceptibility to infections. Lower body temps don't really kill pathogens, so while it isn't necessarily a disadvantage, the peaks of the susceptibility curves lie at the extremes of human body temps, with you probably wanting to lean on the warmer side.
Extra stuff: During an immune response, inflammation causes pyrogenesis in the body (in the form of increasing cellular metabolism, since metabolic rates are correlated with body temp) that disrupts small-scale functions. Of course, at high enough temperatures, this begins to chain into disrupting large-scale functions that the human host needs to survive, so fevers are good for your immune defense but only so much.
People at lower body temps normally would have to burn up a lot more energy to reach the same fever temperature since they would need to make up for that few extra degrees. This actually puts a lot of strain on the body's thermoregulation and homeostatic systems, which can cause a lot of issues. A big one is that most people who were operating at a lower body temp had a low resting metabolic rate. This usually coincides with something like malnutrition, comorbidities, homeostatic dysregulation, or even just old age- all of which make one more susceptible to diseases in a multilateral manner. This means if you're cold, you can't just huddle up in a blanket and except to lower susceptibility, but there is indeed a relationship between temperature and infection | 96 | 348 |
I believe that people who pick a highly saturated major shouldn't complain about a lack of jobs, CMV. | A crisis that has been occurring over the past few decades has been an influx of college students in a broad range of fields while respective job fields haven't changed accordingly across the board. For example, someone with an art or humanities degree will have a much more difficult time finding a job related to their field with a Bachelor's degree than an engineer would with the same degree.
This has caused a lot of people to gripe about the lack of jobs. People feel that they are owed a job for going to college. I'm well aware that this is a result of a promise of the "American dream" and the indoctrination in teens that they have to go to college to get a decent paying job, but neither of those outright declare that any college degree will result in a well-paying job.
If you're going to college merely to get a job right outside of graduating with a Bachelor's, then you should focus your study on a major that has a lot of jobs available. If you just want to make money, then become an engineer or pick another STEM field (even though science isn't necessarily the best way to make money).
If you want to work in your field because you have a passion for it, then you need to work hard. A Bachelor's degree simply won't cut it - you have to be willing to put in more time for school to earn a better degree if you truly want to work in that field. Competition is prevalent everywhere, and you aren't simply guaranteed a job because you graduated college.
This isn't to say that I don't think we shouldn't have people studying all of the subjects that are prevalent in the world - I value all fields of knowledge. However, I don't feel that people should believe they are *owed* a job. Instead, people *earn* it. | Why do you believe that people pursue these degrees?
Maybe, if you understood why people intentionally chose majors with less applicable use in private industry, you wouldn't be so frustrated with their complaints.
One of the reasons that these people feel entitled to their desired occupations in an oversaturated market, is that they were only ever told that they "could do it if they wanted to." That's it. No intense career advice, no special programs, no parental discipline, and especially no market realism.
Another reason that people major in the humanities and social sciences is NOT because of a natural disability in physical sciences, or possibly even a natural dislike for the subjects. Post-Cold War America's trend of increasing demand for technological skills and better equipment has not changed, however, the government sponsored push for quality educational tactics and funding most definitely did.
You see, the arms race with the Soviets included not only nuclear warheads, but a struggle to produce the biggest bunch of smartest technical minds that the superpowers could extract from their populations. Educational funding was at all-time highs between the fifties and the late eighties. Math and the sciences were rigorously applied in public school curriculums. Students had to work harder because teachers had better incentive and funding to allow for time and better programs.
The sad truth is that teachers today are less skilled and have less time due to low incentive granted by educational funding in the US. Math and Science, being complex to learn for most without guidance, are easily given up on without heavy teacher encouragement. Instead of concentrating harder and working to pass classes, students may give up on their abilities to perform this work at an early age. Most people are afraid of math and science because, at a tender learning point, they were abused with poor teaching, impatience, and little guidance to understand how much they would need these skills later in life.
People are smart. We are curious. We also have emotions and egos. We want to learn, and if attempting to learn math and science is made too difficult, people will turn their attention to social sciences because they come a little more intuitively. Then they will wrap their egos around these subjects and think that this is where their skills lie. That is how the market for these professions became especially oversaturated in an increasingly technical world.
Can you imagine how hard that must be for these people? Everything they thought they could do, that made them special, all seems untrue now, and they *have* to blame it on themselves. Who else can they blame it on, society? But really, they can. | 21 | 56 |
ELI5: How does a digital camera "know" what to focus on? | I tried to find similar answers but none that hit the nail on the head as to how the camera "knows" what to focus on. What I mean by this is how does my camera know to focus on a specific person or thing, when there are countless other things it could focus on.
Say, a picture of a person with a stop sign behind and some trees also, how does it recognise the person and ignore the sign and the trees? | There are two methods for cameras with autofocus...
Focusing on the object in the center or at a preset focus area. This is determined by the photographer and/or camera.
The newer method uses machine learning for subject detection and selection. What is the photographer trying to take a picture of? Is it human? Does it stand out more than other objects? face detection, etc. Sports photography is slightly different, it’s not machine learning, but uses the chip to track objects once selected so you can burst while the subject is moving and maintain focus.
As far as how it actually focuses, there are a couple methods like phase detection or contrast detection of the subject once the camera or photographer has identified the subject. | 18 | 25 |
CMV: Having a military is just as "socialist" as having universal healthcare. | In short: if the US government is willing to spend billions of dollars on defense, and millions of Americans support this defense spending, why do many of the same people fight so adamantly against the government paying for healthcare?
A lot of us don't agree with defense spending (myself included). A lot of this "War on Terror" has just proven to be an inconvenience for ordinary citizens - just look at the TSA and what we have to deal with to get on board a plane. Others are blatant violations of privacy, such as NSA surveillance.
Some people disagree with how universal healthcare should be run, and wouldn't support it with their hard-earned dollars. But if a similar number of people don't support sending our troops abroad to fight wars that almost nobody has an interest in.
To be clear: I strongly support implementation of healthcare as it is executed in the Nordic countries (and I advocate the Nordic model in general). I'm not saying only socialist countries should have militaries, but I do say that the implementation of national armed forces and healthcare are too similar from a purely economic perspective to support one and oppose the other. (Socially and politically, of course, they are radically different.)
[edit] I'm not saying that a national military is a socialist idea, either. Just that there's a good similarity. Hence the quotes around "socialist." | What you provide to people, they have reduced need to provide for themselves. If the government provides military defense, playgrounds, or three-toed-sloth-crossings, socialism-haters don't get bent out of shape because they weren't really rooting for people to pick up rifles and head to Iraq, build sloth crossings, or build big playgrounds. On the other hand, if you provide food or health care it upsets them because they think a big part of what you should do in life is work to afford food and health care.
Additionally, socialism-haters worry that the government will make benefits contingent on conformity. If it's providing you with food and health care, it can say "food stamps not for druggies" or "no lung surgery for smokers" or "Tea Party activists are slightly more likely to be denied for a second knee replacement". Whereas the government can't very well defend only some people from invasion, or only allow correctly-voting people on the playgrounds.
| 29 | 65 |
Could a vampire live ethically? Would we have a moral duty to them? | For the purpose of this question, I'm assuming that the vampire is like a human being in every way except that it needs to drink human blood in order to survive. Let's also assume that they need to consume enough blood a day that it would almost definitely kill the person they feed on.
This is sort of inspired by [this](https://www.youtube.com/watch?v=m0YB6_7Kync&t=45s&ab_channel=NPR%27sSkunkBear) video about Vampire Bats in Central America, as well as my own current interest in vampires (and bats!). There's obviously some differences between the two scenarios but I think there's some commonalities as well. The vampire bats are, as far as they know, not important to the ecosystem in any way, and their continued existence necessarily puts the lives and livelihoods of the ranchers at risk by exposing them and their cattle to rabies. | I want to hit on the second paragraph as an ecologist. Im worried whenever people suggest something has no ecological function, usually that says more about our model of the ecosystem than the organism. There are also non-destructive (also destructive interventions are notorious for just not working) interventions that could exist. | 37 | 59 |
If there are nutritional labels on all of the food we buy, including water, why is there not a nutrition label on liquor? | Why no nutrition labels on the liquor bottles we buy? Isn't it important to know about what we are drinking?
EDIT: For everyone saying there is no nutritional value in liquor, yes you are correct. However it still has calories. They put nutritional labels on bottles of water and that has no nutritional value or calories. | In the US food is regulated by the FDA. They are the government body that forces companies to put the labels on all food and beverages. The FDA does not regulate alcohol, alcohol falls under the purview of the ATF. The ATF doesn't require nutritional labels. | 804 | 1,745 |
ELI5:How do YouTubers make money? Is it a combination of subscribers, views per video, ads? | YouTubers earn money through ads on their monetised videos. Viewing an ad provides a small amount of income towards their channel. Since it requires the ad to be displayed, if you run adblock, your view does not count towards what they get paid. Unless they acquire sponsors or a donation system, this is the only way they make money from their channel.
However, where figures like subscribers, views, likes and viewing time per video come in is marketing - the more watched/liked/subscribed you are, the more likely YouTube is to promote you to other people. As such, you don't actually make money from having subscribers, but they do represent a consistent source of income and help in sharing your video with the world. | 32 | 36 |
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Are there "degrees" of moral realism - i.e., do most/all moral questions have an objective answer or only a few? | Moral realism, as far as I understand, is the position that _there exist objective moral truths_.
That seems to me a fairly weak statement, though. Even if we accept that there are objective moral truths, it is conceivable that there exist only a few such truths and that the great majority of moral questions have no objectively correct answer but remain subjective. It is, of course, also conceivable that there exist objectively correct answers to every conceivable moral question.
Of the arguments that I've seen in support of moral realism, all the reasonable ones seem to support only a very "weak" moral realism in which only fairly trivial moral questions have objectively correct answers.
(An example of a class of moral questions that seems unsolvable to me is that of animal ethics. How are we supposed to determine how much one animal "matters" compared to another animal? There are attempts to grade animals by intelligence so that smarter animals matter more than dumber animals, but this is obviously very subjective and inexact, and it seems to me impossible to ever reach a detailed conclusion that is more than an awkward compromise.)
Is this a thing in meta-ethics? I.e., is it acknowledged that moral realism can be "partial" in the sense that only a proper subset of all moral questions have objectively correct answers? If so, are there any philosophers who argue for a "stronger" or "weaker" kind of moral realism than other philosophers? | Scanlon talks about this issue in chapter 4 of *Being Realistic about Reasons.* He argues that there are objective moral and normative truths, but he stops short of saying that all of moral and normative reality is fully determinate in the sense that there is determinate truth value for every moral and normative claim. With that said, he's not suggesting that there are only a few objective moral and normative truths. His point is mainly just to note that some moral and normative issues may not have objective answers despite the truth of moral realism.
His stance on this topic is related to the fact that he endorses relaxed rather than robust moral and normative realism. According to Scanlon, what's important for moral and normative objectivity is that there are standards of moral and normative reasoning that allow us to adjudicate moral and normative issues. He relies heavily on a math analogy, and specifically an analogy with set theory. His idea is just as there may be multiple different ways of conceptualizing the standards of reasoning about sets, which imply many of the same conclusions but also sometimes different conclusions, the same might be true about moral and normative standards. And if there is no way to identify one set of standards as the objectively correct ones, that means there is no determinate answer to the claims where those standards conflict.
EDIT: It may be worth noting that part of the reason why the issue of determinateness is worth commenting on at all is that Dummett famously argued that because mathematical reality is indeterminate, we should therefore be mathematical anti-realists. So, Scanlon is making it clear that one could accept indeterminateness about moral and normative reality and yet also be a moral and normative realist. | 17 | 61 |
What did Aristotle mean when he said women's capacity to reason "lacks authority" (Politics 1.13)? | I'm still puzzling over this text. What does it mean? | The mention is very brief and his exact meaning is unclear, but it is typically interpreted in two ways: 1) Their rational capacity lacks authority over the non-rational part of their soul, i.e. women are naturally emotional; or 2) their rational capacity lacks the authority to command other people the way the male head of the household does, i.e. women are naturally obedient. | 68 | 61 |
ELI5: why hasn't the US seen more recent unmarried presidential candidates? | A good prospective first lady can be a huge asset in a campaign. They can attend rallies and fundraisers while their husband is elsewhere on the campaign trail. They can stress a different set of talking points, and thereby appeal to a different demographic of voters.
So an eloquent, politically active wife is kind of a force multiplier in a campaign. Bachelor/widower/divorced candidates are essentially playing at a disadvantage. | 20 | 17 |
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Ok... so what kind of processing power do we not have that it would have to take, to attribute all our known physics into a computer simulator? Consequently for running anything and everything 'real life' inside of a video game? | I guess since it takes our universe to hold all the laws of physics that it does, then it might be very unrealistic to imagine some computer program that implements it all as well? Are the numbers real though and calculable for what it would take? Is there a chance you could really make a video game that looks normal, but really, any action is based on every atom and molecule and force it consists of, and would literally mimic real life? I.E., a real/true simulator?
edit: thanks for all the awesome replies, everyone! I had a great time reading! | Something to give you an idea:
Suppose you have a mole of nitrogen gas at standard temperature and pressure. That's 6.02 x 10^23 molecules.
Each one of those molecules will have 1.3 x 10^9 collisions per second, on average.
That's 8 x 10^32 collisions per second. And that just describes the behavior of whole molecules. You still have to deal with the electrons, etc.
A computer is pretty fast if it can do a petaflop (10^15 floating point operations per second).
To model just the kinetics of a mole of nitrogen gas, you would need 8 x 10^17 of those computers. To put this into perspective, the oceans contain approximately 1 x 10^19 gallons of water. | 19 | 20 |
ELI5: In the United States, why are positions like Attorney General, Secretary of State, etc. appointed by the president at the federal level but elected by the people at the state level? Had it ever been proposed to do this differently? | The federal government was designed to primarily be a representative of the States, while the States would represent the People.
This is apparent in how the Federal Senate was initially chosen by the state legislatures (prior to a constitutional ammendment), and the Electoral College was initially also selected independent of the popular vote (that's screwy ATM because of state-level laws). Indeed, the House of Representatives still gets 0 say in federal nominations, appointments, or treaties.
As the State governments were viewed to be much closer and more relevant to the People, their state constitutions generally reflected this in directly voting in many more positions. | 27 | 215 |
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ELI5: I've heard pirates drank rum because the water would go rancid. How does water go bad? | Water unless it has been distilled and is stored in a sterile container that is sealed air tight it is contaminated with various kinds of microorganisms such as bacteria and fungi. These will grow in a stagnant water supply (such as in the water barrels of a ship) and it will eventually get to toxic levels. | 102 | 53 |
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CMV: I believe the Collegeboard is a scam | As I said in the title, I believe the Collegeboard is a scam. The reason I say that is because they are slowly taking over the US educational system. Public schools are paying the Collegeboard for having AP® courses in their schools. Some schools pay for students taking test, as it will make the school look good. People use the amount of AP® courses in order to determine how good a school is. It also shows the amount of income inequality, as schools with a lot of money have more AP® courses than ones without. I believe that instead of schools having AP® courses and making students take a stupid test, schools should offer dual credit courses, which would offer both college and high school credit and teachers would have a broader curriculum.
The SAT is the same story. Instead of using that test, universities should make their own test, and the students that are interested in taking the test or want to go to the university would take and the test would determine If the student is qualified for that ONE university they want to join.
I see it inside the school I attend how it has been affected. I hope we, as people, can change it.
Edit: added the last part and I wrote this on mobile, so sorry for not knowing where to put the disclaimer. | If Choate and Municipal High both offer dual credit courses, MIT isn't about to give college credit for both of those. It knows that Choate has a good dual credit course, so it might accept Choate's course. But Municipal High's "dual credit" course might not be at that level. Right now, MIT can say that an AP course at Municipal High with a score of 5 counts for college credit. But without the AP test, what tells MIT that Municipal High's "dual credit" course is at a college level?
Regarding the SAT, the main issue is that having to take twenty tests to get into twenty schools would be a serious cost (in $ and time) for the applicants. This wouldn't matter too much for rich kids, but it would be a severe handicap for poorer students. | 128 | 352 |
ELI5: What are sushi masters doing that is so masterful? | I know this is kind of an ignorant statement (this post is my attempt to combat that ignorance), but I watched documentary on a sushi master, and it looks like he takes a piece of raw fish, combines it with a clump of rice, and brushes it with a little sauce. And it apparently took him 30 years to master that, and he's still learning.
What about that takes decades to develop, and how is it different from someone with less experience combining the same handful of simple ingredients would produce? | it starts by the chef choosing which fish to buy from the market. is it a good fish? a great fish? what parts of the fish are good. what parts are great?
once the fish gets to restaurant, how do you cut the fish? what angle
do you cut it? what's the action of the knife cut? which parts of fish fit which dishes?
alot of making sushi is in the making of the rice. what kind of rice are you using? how much water? what temperature? how long are you cooking? how much rice vinegar are you mixing in? how quickly are you cooling down? is the action that you're stirring in the rice making it more or less fluffy? sticky? chewy?
| 57 | 57 |
ELI5: Do dogs recognize that their name is their identity or do they simply know to respond when a certain sound is made? | Dogs are capable of recognizing their names, and discerning it from other sounds. Recent animal behavior studies have found that dog's brains behave in much the same way our brains do when someone says our name. It appears that they are able to recognize that their name is not just another sound that someone is making, but is meant to specifically identify them.
Edit: Fun fact -- cats have been shown to do this as well. The research suggests that cats can also tell when you're using their specific name. The reason they often don't react? They don't care. | 5,212 | 4,587 |
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ELI5: The controversy surrounding GMO. | For a long time, people have been breeding plants and animals to be better for humans - cows that produce more milk or tomatoes that are tastier or more durable. A while ago, scientists figured out a way to do this much more quickly, so they can achieve their goals faster and more efficiently. Some people are afraid of this new way because it is strange and different, and others are concerned because many of the groups doing it are big corporations who aren't necessarily acting in the best interest of everyone else. | 12 | 25 |
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ELI5: How does sniffing glue and sharpies make you high? | Always wondered this I see posters in my school about it too | Chemicals like those found in certain markers, glues, paints, and other solvents contain chemicals that readily turn into gases when exposed to air, and when you breathe them in, the gasses readily absorb into your bloodstream and get carried to your brain. Once in your brain, they act in one of two ways - either they simply displace oxygen (so the high you feel is actually from lack of oxygen), or they mimic, interfere with, or alter the effects of certain chemicals in your brain called neurotransmitters that are responsible for brain cells sending signals to each other. | 8,408 | 10,357 |
ELI5: Why would a butterfly be attracted to a human? I recently watched a video (link below) where a Monarch Butterfly (named Penelope) hung out with this guy for about a week. I would like to understand why a butterfly would do this. | https://youtu.be/327WTVWI0Qw | Butterflies tend to eat nectar or other sources of salty or sweet liquids. Humans are covered in salty-sweet sweat, sebum, and other skin secretions which are tasty to insects and other animals. Additionally, some humans use soap, body wash, shampoo, or perfumes which may smell floral, further attracting insects.
Furthermore - this is a self-reported incident. It's very likely that the person in that Youtube video is exaggerating the butterfly's attraction to him because he wants to think it likes him. | 289 | 404 |
ELI5: How exactly does cancer kill? | Obviously cancer is bad, but I never understood how exactly it kills. | When people get cancer, it affects certain organs. How bad the cancer is depends on what organ it's growing on (although, no cancer is good). Things get really bad when the cancer *metastasizes*, that's when it spreads to a different organ.
When an organ has cancer, it's like it's carrying around a 50 pound backpack full of stuff it doesn't need and it gets tired really easily. There comes a point when the organ is so tired it's not going to work at all. When this happens to an organ that you need to survive, you die. | 34 | 39 |
Why can the sum of two cubes never be prime, but the sum of two squares can? | 1 is the only number that gives you a prime from what I've found, because 1^3 + 1^3 = 2. Im pretty sure the sum of two numbers that are both to an odd power can never be prime, but im not sure. Is there a proof for this? | Assuming positive integers
a^3 + b^3 = (a + b)(a^2 - ab + b^2 )
(a + b) will be a factor of the number, and for positive integers
2 <= (a + b) < (a^3 + b^3 )
Thus, whatever number you get will always at least have (a + b) as a factor that's not 1 or itself, with 2 as the exception.
**EDIT:** bad assumption, proof should be fine now. | 16 | 15 |
ELI5: What are free trade agreements | How come we still have to pay large tariffs and duty on countries where we have free trade? I went to France and bought a wheel of eppoisses cheese for like 4 euro. But if I want to buy it where I am in Canada now it's around 20 dollars. How can average people benefit from these agreements because I really don't think they do. | Free trade agreements are contracts between countries that allow goods to be imported without tarrifs or with reduced tarrifs. In the case of two countries with similar economies they allow goods to be imported cheaper and the cost savings are theoretically passed onto the consumer increasing purchasing power and economic output. With developing countries it tends to be a mechanism to lower manufacturing costs then import the goods back without penalties. CETA, Canada and Europe's potential trade deal has not been finalized so you are still paying for the cost of the tarrifs. That's why it's more in Canada. | 22 | 109 |
CMV: As a heterosexual male, it is inescapably to my advantage to live in a society where women tend to underestimate the value of their attractiveness. | *"Oh, oh oh. You don't know you're beautiful. That's what makes you beautiful."*
...or however that song goes.
This is a conclusion I come to that's one of those, "I can't escape that this is true, however poor the implications seem," kind of things. In an economic situation, someone who underestimates the value of some asset if a boon for those looking to negotiate with them. Is dating a negotiation? I would argue it is at a little bit, whether we like to think of it that way or not.
As a heterosexual male, I value attractiveness in the women I want to date. I also understand that what I have to offer has to be comparable with what the other person has to offer...or, importantly, what they *perceive* they have to offer. Thus, I am going to be able to achieve better results for myself in a marketplace where women think less of their own attractiveness, and underestimate it compared to how highly it would actually be valued by men.
Conversely, the last thing I want is for a potential very attractive date, naive to the fact that she could probably do better than me, to realize that fact. This leads to some ugly notions, like the idea that society shaming women for not looking perfect, and holding up supermodels and the like as the unrealistic standard, are actually to my benefit.
Someone on my facebook crawl recently posted that a study found a fairly small amount of black women thought they were depicted as beautiful in the media. I immediately combined that in my head with studies I've read about how black women being the female demographic that does worse on dating sites, and also a reflection on my own experiences: 'Yes, I have had an 'easier' time dealing with black women on dating sites. They do tend to seem more appreciative of the attention, less entitled, etc.' And, to no surprise, I like that. In contrast, the last thing I want to have to deal with on a dating site is someone who overestimates the value of their attractiveness. I started with a song, so I might as well end with one:
*Dear future husband
Here's a few things
You'll need to know if you wanna be
My one and only all my life*
*Take me on a date
I deserve it, babe
And don't forget the flowers every anniversary*
*After every fight
Just apologize
And maybe then I'll let you try and rock my body right*
*You gotta know how to treat me like a lady
Even when I'm acting crazy
Tell me everything's alright*
-Meghan Trainor...attempting to sell herself pretty high
So far, I've found it pretty impossible to escape this conclusion, but I dunno if someone has a view on this that might offer something I haven't considered?
_____
> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | Undervaluing your own attractiveness is a symptom of a larger sense of low self esteem which affects all areas of a woman's (or man's) life.
Lacking self confidence will lead people to underestimate the value they have to add to any given situation, which means less likelihood of promotion in the workplace, general sheepishness, clinginess, etc. All negative traits. This applies to both sexes btw. | 48 | 45 |
Escaping from Malthusian trap | I was reading the part of The Economy book from CORE team and had a part I don't understand. It says [even productivity increases in the long-run the wages will return to subsistence level and this is called Malthusian trap/stagnation](https://www.core-econ.org/the-economy/book/images/web/figure-02-17-e.svg). In the following unit the book says "...They did not consider the possibility that improvements in technology could happen at a faster rate than population growth, offsetting the diminishing average product of labour.
The permanent technological revolution, it turns out, means that the Malthusian model is no longer a reasonable description of the world. Average living standards increased rapidly and permanently after the capitalist revolution."
How these two things do not contradict with each other? Aren't they the same thing? | The first statement is about one-off productivity increases, while the latter addresses continuous productivity improvement. That's the source of your confusion.
I don't have time to find the papers right now, but the Malthusian equilibriating force appears to be real but weak in the historic record. So it takes a long time after a productivity improvement for standards of living to return to a subsistence level. Nowadays, we have so many technological improvements that the Malthusian equilibrium is no longer relevant (even in poorer parts of the world).
But the real Achilles heel of the Malthusian model is that it doesn't have a sophisticated enough understanding of why people make the reproductive choices that they do (one might say it "lacks micro foundations"). As a result, it did not foresee that, as societies modernize, birth rates consistently plummet as people prioritize careers and female empowerment. This is called the "demographic transition model" and has been very consistently observed across the world. That's the other big reason why the Malthusian model isn't relevant anymore (at least for human societies). | 41 | 38 |
ELI5: How is oxygen (O2) odorless but ozone (O3) smells and is hazardous? | O2 and O3 have different chemical structure (bond angle, length, spatial orientation etc) which give them different physical and chrmical properties.
Just like graphite, diamond and fullerene are pure Carbon but have drastically different properties. | 39 | 20 |
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ELI5: What exactly makes something a vitamin and how did they get their names (C, B6, B12, E, etc)? | Vitamins are small organic molecules that we need in tiny amounts in our diet. So for example amino acids are not vitamins because we need large amounts of them. Sodium is not a vitamin because it is inorganic.
As for the name, basically they were lettered in order we realised their existence. However knowledge was incomplete (and may still be incomplete) so it turns out that what we thought was one single vitamin (B) was in fact a complex of several closely related substances, so those got numbered. Some of them were originally vitamins G-J, hence the sudden jump to vitamin K. Others were found to be non-essential and dropped. | 46 | 42 |
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ELI5:When does light stop? | Today i was walking along a lake on a beautiful sunny day. I noticed the reflection of the mountains off the lake. I realized that what i am seeing are photons bounced off the lake, but then i realized they were 1st bounced off the mountain, and they came from the sun.
When does the photon stop? | Whenever light hits something, some of it is absorbed and gets converted into another form of energy (heat), while some of it is reflected. When you the light hits your eyes, it is absorbed by your retina. | 34 | 62 |
ELI5 why is water the only (one of the only?) substances in which its solid form floats on its liquid form? | Water is a polar molecule. That means one side of it is more positively charged and the other side is negatively charged. When water is in liquid form, the energy and movement of the individual molecules is sufficient to trump the effects of these positive and negative poles.
But as it cools and begins to freeze, the molecules lose energy and the electromagnetic forces from these poles takes over, causing the molecules to arrange in a crystalline structure which is less dense than in liquid form. Since it is less dense, it floats. | 141 | 124 |
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ELI5:What is quantitive easing? | I am an intern at a financial institute and constant talk about bernacke and this policy have gone around but I don't understand it completely. | One of the jobs of the Federal Reserve it to help set monetary policy for the United States. One of the main ways it does this is by setting the Federal Fund Rate. This is an interest rate that banks pay each other for interbank loans, but more importantly, almost all other interests rates (home loans, credit cards, etc) , directly or indirectly, are related to this rate. The lower the interest rates, the easier it is to get a loan, which makes expansion (personal or business) easier, which generally increases growth. When the economy is going along good, the Fed raises interest rates, which slows things down a bit, and when it's going poorly it drops interest rates to give things a boost. What it's attempting to do is avoid boom/bust cycles (which obviously it can't eliminate given we are still recovering from a giant economic bubble bursting), and provide steady continuous long term growth. In the wake of the housing bubble collapse, the Fed dropped interest rates from around 5.25% to it's current rate of 0.1%. That's literally almost nothing, and it means that the Fed can't continue to use decreases in interest rates to spurn on the economy. Given that the unemployment rate is still very high, and in general the economy is on unstable ground, this is a bit scary. Basically the main nob that the Fed uses to push the economy into action got dialed to 11, and that's still not working.
That led the Fed to adopt an additional policy called Quantitative Easing (QE). Basically the central bank purchases very large amounts of public bonds. Bonds are traditionally a safe place to store you money, with low by reliable returns on investment. By buying up large amounts of these bonds, they are denying people and companies from being able to have access to that safe place. If you don't invest in anything (just keep a pile of cash sitting around) then the value decreases over time because of inflation. So basically the Fed is forcing people to invest in some other project (like expanding business ventures) if they want a decent return on their investment. This, coupled with historically low loan rates, means it's very good time to invest in those sorts of projects, which should increase their frequency, which should give the economy a kick in the pants. | 30 | 44 |
How do we communicate wih people who are blind and deaf? | Serious question...How are we able to teach people to attain some autonomy if they cant hear or see us? | First of all, it is very uncommon to be born both deaf and blind: mostly people are born deaf and gradually become blind or vice versa. Therefore, they start with learning special sign language and/or braille at a young age. Communication with deaf-blind people usually goes through special interpreters (deaf-blind); they make signs with the hands of the deaf-blind person, or spell letters in the hand of the deaf-blind person. In answer, they do the same. Communication therefore is slow but not impossible. Source: sister is a deaf interpreter who did a minor in deaf-blindness. | 15 | 28 |
ELI5: How do blisters form? And whats in a blister? | Living tissue, as a general rule, is wet. Living cells like being wet and generally require a fluid environment to function. Many living things have to stay constantly wet or they simply dry out and die (or go into stasis).
So human beings are just a large collection of cells, the vast majority of which are constantly bathed in fluid which they require to function and live. We have a few specialized cell types which exist specifically to form a barrier between our living cells and the outside world. In humans this is primary skin and mucosa. Broadly speaking skin covers the outside of your body, mucosa lines the inside.
Let's set mucosa aside for a moment. If you damage, break, cut or scrape your skin, the protective barrier is broken, and something will leak out. Obviously blood, but that will clot off after a while. Without intact skin all tissues will leak serous fluid even if there is no bleeding. Now this can dry out and form a crust or scab, but if you keep it moist it will produce fluid indefinitely until (hopefully) new skin heals over it. Some tissues don't produce enough fluid to survive exposure for extended periods, and they die (bone, tendon, and ligament being notable examples). Usually people don't notice this fluid because blood predominates, unless they pick at a scab or have an open wound.
A blister forms when the skin is damaged but the top layer of keratin, ("dead skin cells", though that's not really a great way to think of it) stays intact. The top layer of your skin is actually pretty tough, so you can kill or damage some of the living skin cells underneath, while having top layer stay in one piece, say through through friction or a burn. Since the skin isn't doing it's job anymore the exposed cells underneath start producing fluid. If the skin is dead but still intact on top it collects and forms a blister. If not you just have an abrasion/wound.
Note that enough physical trauma to damage the skin is usually enough to create defects in your epidermis. That's why blisters are most common on areas where the skin is particularly robust (hands and feet) or when you have burns (can be severe damage that doesn't break the skin).
That's the 5 yo version anyway. | 14 | 15 |
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What exactly was Schrodinger trying to prove with “Schrodingers Cat”? | Schrödinger proposed the cat thought experiment to illustrate the _problems_ with the Copenhagen interpretation of quantum mechanics. It was meant as a _reductio ad absurdum_, an argument that shows that if you take a train of logic too far, you get silly results. Specifically, the idea of quantum superposition being related to observation — maybe you think it's OK that we can't know the quantum properties of an electron without some kind of observation (e.g., bumping it with a photon), Schrödinger is saying, but if you scale up the issue to macroscopic objects, it becomes just ridiculous! Schrödinger wanted a quantum theory that dispensed with such things like observation-based wave-function collapses and superpositions of states (there are various other ways to try and interpret quantum mechanics that get rid of them). Schrödinger has hardly been the only person to have these objections, and not the only thought experiment to do something like this (e.g., Wigner's friend is another), but his example for whatever reason (perhaps it is just weird enough) is the one people know popularly.
The irony is, of course, that Schrödinger's cat has become _the_ way to explain quantum superposition of the Copenhagen interpretation; it has gone from a ridiculous argument to the easiest way to explain it to laypeople. The difference is, the story becomes a "I know that sounds crazy, but that's how crazy the world really is!" sort of story, as opposed to a "I know that sounds crazy, so it must be wrong!" sort of story. | 49 | 15 |
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ELI5: Why do we get sick when its' cold? Does it have to do with the temperature or some other factors? | This question always gets answered with the received wisdom that goes something like. 'It's not because of the cold, it's because we spend more time in the warm indoors with other people....' well that's not actually true, it IS because of the cold AS WELL.
When we're cold, our bodies restrict blood flow to our extremities, including our nose, to protect the vital organs. Less blood flow means less white blood cells reaching the nasal passages so infections which start there are less likely to be fought off in the early stages and so they're more likely to get bad enough for us to notice them.
| 20 | 25 |
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ELI5 how do cameramen and women in films hide the cameras whilst filming so well when there is a scene with reflections? | Whenever I’m watching a movie and there is a scene with mirrors or something that causes reflections I’ve always wondered how they are able to hide the cameras so well? | Scenes are carefully choreographed in advance, including the camera angle. That's the behind the scenes you see of the cinematographer walking around holding a lens to their eye. Sometimes, particularly with mirrors, they shoot with a non-plano camera that has a distortion opposite the the effect of shooting at an angle. In the worst case, they just edit them out in post, like CGI only backwards. That's how they remove wires and support structures. | 10 | 18 |
ELI5: Why do hallucinogens make you hallucinate if they are just binding to the same dopamine and serotonin receptors as other drugs. Why and how do shrooms and lsd and stuff physically alter your vision and make you see stuff you dont see? | Neurotransmitters are critical in the process of creating neural "pathways", the transmission of electrical signals from synapse to synapse to synapse. Part of that process is for the neurotransmitters to "bind" (attach) to certain types of receptors on the synapses. LSD and other hallucinogens disrupt how this process is supposed to work, as they can bind to the receptors but don't work like the natural neurotransmitters are supposed to.
In this way, they actually create spurious pathways in the brain that would not otherwise occur. In addition, in some parts of the brain they appear to inhibit the operation of the normal pathways, reducing the function of those areas. Part of that action seems to inhibit some of the sensory filtering that normally occurs in the thalamus (IIRC), so other areas of the brain are bombarded with information they usually doesn't have to deal with. This may cause the formation/use of more pathways than normal, or at least, different pathways. | 70 | 141 |
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What am I doing wrong on campus visits? | I know it's impossible to know exactly what the answer to my question is, but I thought I might get a little help. I'm trying for rather high-level jobs (TT at R1 or R2 schools). I get interviews and campus visits, so I'm doing something right. BUT I don't get job offers, so I'm doing something wrong. I have absolutely no idea what that thing is.
I did ask a friend who was on one job committee what I could do better, and she had some minor tips but nothing I'd see as a red flag. Her main answer was "I'm not really sure."
So what do you think? What are some things I should be mindful of? What are things you've seen people do that disqualified them (or made them a less desirable candidate)? What things did you see people do that endeared them to the committee? Any help would be greatly appreciated. | Another thing to consider, which I've seen multiple people screw up on in academic job searches, is that your interview begins the moment your plane lands in the city and doesn't end until you get back on board. Yes, the secretary doesn't get to decide if you get the job, but they certainly have influence on if you don't get it.
People tend to let their guard down after the interview is over, for example when they give you a campus tour. Or in line at the off-campus Starbucks in the morning before the interview... Especially in smaller towns where everyone seems to know everyone else.
Some interviewees have totally blown it outside of the interview. Remember to always be professional and courteous to everyone you meet throughout the entire visit. | 43 | 33 |
Is using mouthwash products such as Listerine actually beneficial to your gums? Are there any adverse effects? | I was googling this and there were a lot of articles arguing both ways, some saying that it kills the bad bacteria but also killing the good bacteria as well.
Other articles were saying how it actually contributes to making bad breath even worse, also damaging your tooth enamel.
| Dental student reporting in: what I've been taught is that most mouthwashes don't do very much aside from making your breath smell nice. One important exception is Peridex (chlorhexidine) which is the last resort stuff prescribed by dentists when patients really need to have better hygiene and nothing else is reliable. Also, Peridex turns teeth brown. Mouthwashes with fluoride have been shown to have some beneficial effects for remineralizing very small cavities (ACT brand has fluoride in it). Alcohol containing mouthwashes are kinda iffy in that alcohol can contribute to oral cancer (alcohol works synergistically with smoke). Specifically in terms of benefits for your gums: regular flossing, mild stimulation with a brush, and a cleaning every few months are more than adequate solutions to gum disease.
Sources: Mouthrinses for the treatment of halitosis
Zbys Fedorowicz, Hamad Aljufairi, Mona Nasser, Trent L Outhouse, Vinícius Pedrazzi
Editorial Group: Cochrane Oral Health Group
Fluoride mouthrinses for preventing dental caries in children and adolescents
Valeria CC Marinho, Julian PT Higgins, Stuart Logan, Aubrey Sheiham
Editorial Group: Cochrane Oral Health Group
Tl;dr: Mouthwash does not appear to really help your gums that much and alcohol containing mouthwashes like most types made by Listerine appear to have adverse effects. | 845 | 1,486 |
[Mass Effect]What most likely happened to the Asari in the aftermath of the Reaper War? | Once it became common knowledge that the Asari hoarded Prothean technology for themselves and possibly knew about the Reaper threat long before Sovereign turned Saren, how would the rest of the Galaxy have reacted to it? | Did it become common knowledge? Shepard found out, but it's not like she had the time or motivation to blab about it to the galaxy as the war neared its end. Plus, she really wasn't in any shape to continue talking about it afterward.
Besides, in the immediate aftermath of the war, who really cared? It was over once and for all, and everyone got a chance to rebuild. If anything, the Asari used their surviving technical superiority to aid all the other races in recovering. They would naturally prioritize their home world and colonies, but it was likely the Asari who spearheaded the repairing of the relays and the rebuilding of general galactic travel and commerce.
Now, PERHAPS, if the galaxy found out around the time that reconstruction was over and the galaxy returned to normal, that shit might have gone down. But in the new era of cooperation and peace, (mostly because most galactic militaries would still be in tatters) the Asari would probably just pay economic fees, or be "forced" to share some of their secrets. | 42 | 49 |
Eli5: Why does research take so much computing power? | I always hear about scientific research needing crazy amounts of computing power but I have no idea why. As someone with an interest in hardware, I’ve always been intrigued by this. | A lot of of problems that come up in science are not solvable by straightforward algebraic methods. Things like protein folding, fluid dynamics, stress/strain, gravity/orbits with multiple bodies etc end up with fairly complex differential equations. In the past, the only method was do make a lot of simplifying assumptions in order to make the problems tractable. As computers develop, there needs to be fewer assumptions and the computer could do a lot more grunt work calculations to get more accurate answers. But there are still classes of problems that are best approached using simulation. These generally require stepping forward in small increments (usually time) and solve the state of the problem, then step forward in time and use the end result of the previous stage to calculate the current state.
This requires huge amounts of computing power if the time steps are small and if the systems for each state are complicated (say modelling movement of all the stars in the entire Milky Way or weather patterns).
Then there are classes of problems requiring optimization - for example complicated molecules like proteins can be "folded" in many ways (think in terms of trillions and billions of ways) There is no way to predict what "works" so each configuration has to be simulated separately and tested.
Then there are just the complicated observations (say astronomy) and experiments (say the LHC) which generate terabytes and petabytes of data. It would take thousands of years for a person to analyze the data by hand to extract meaningful data and patterns that might be useful.
Some of the examples in research that take advantage of computing power. | 36 | 23 |
[Dishonored] I, Corvo, was recently visited by a mysterious figure, teaching me how to use magical powers of sorts and giving me a strange heart. What exactly is this heart? | Try it out. it can tell you a lot about everything, including itself. Use it on a creature, or just at an interesting location. After a while, you might realize that it belonged to [**Beep spoiler**](/s "your beloved empress."), who are still as loyal to you as you were to that person. | 18 | 15 |
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ELI5: Antilag systems in turbo cars. | A turbocharger works by using air pressure from the exhaust to compress the fuel/air mixture going into the engine increasing engine performance. Unfortunately, there isn't always enough exhaust pressure to run the turbo at the beginning of the acceleration, so there is a delay (lag) between when the accelerator is pushed and when the turbocharger starts doing its work.
Antilag devices solve this by increasing the exhaust pressure even when the engine isn't doing much work. The essence of how these things work is by burning fuel outside of the engine and sending that exhaust through the turbocharger. | 16 | 54 |
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