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ELI5: Why does paper product (paper towels, napkins, etc.) become transparent when wet? | Imagine you are at a restaurant with a self-serve soda dispenser and a clear glass cup. First, you fill the glass with that finely-crushed ice they have at soda dispensers. Now look through the glass. What color does it look? White. Opaque. Like a white paper towel. You cannot see through the glass at all. If there was an object (like a cell phone cover) behind the glass, the ice obscures it completely so you can't even tell what color the object is.
Now fill the glass with cold water (or Sprite™). Most of the crushed ice is in there, but now the glass is translucent. Like a wet paper towel. Although you couldn't read a book through it, you could certainly see the color of an object behind the glass.
When ice and air are mixed in a glass, their very different indexes of refraction make light beams bounce around a *lot*, mixing everything up until you can't see through it.
When ice and water are mixed in a glass, their index of refraction is the same (in fact, if the ice itself didn't have air bubbles inside it, the glass would be almost completely clear and see-through). So less bouncing of light beams.
The wood pulp and other material in paper has an index of refraction closer to water (and ice) than it does to air. So the effect is the same.
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Eli5: why are red, green and blue used to "create" other colors? Why these specific colors? | You might have heard about cones and rods. These are cells in our eyes that send signals to the brain when light is shined on them. Rods respond to most visible light and is responsible for signalling the brightness (black/grey/white). Cones, on the other hand, come in three varieties. One for signalling when blue light is seen, one for green, one for red. Simply put, we use RGB-signals because we can control the balance between those three parameters and easily represent the colours visible to our eyes. | 199 | 184 |
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CMV: If universities expect students to show how unique they are, they too should try and show students what makes them stand out. | I'm a senior, and I've been basically just been applying to universities past school year. Nearly every university that I've applied to expects me to show them how unique I am and how I am a good match for the school. Some schools don't ask those on their essays but do in interviews. On top of that, you can't really talk about your hard work or your collaborative nature, since basically every student says that.
Despite requiring applicants to differentiate themselves from the rest, many universities make no attempt to do the same. Let's take University X as an example. I went to their website on a page which said "Why X" (this was sent to me in an email from them, btw). One of their reasons was dedicated professors who love to teach. Another was great facilities that many other first-year students don't have access to. In my opinion, these are just really generic. Many other schools say the same thing.
Maybe this is just my frustration speaking, but I feel like these schools should hold themselves to the same standards as they hold applicants when it comes to this sort of thing. | If you were grading applications for university, you'd see many of the things that make students stand out are actually kind of common. Hardworking students who join various clubs and activities, or volunteer, or had personal hardships. | 14 | 24 |
[Pokemon] Who pays for all the Poke-Healthcare? Why is direct care free everywhere but medicine is so expensive? | Free health care comes because of the invention of the Poke-Healing Station, which allows for quick and easy healing of pokemon at a fixed location. This was created by the Joy family, which is why there is a Nurse Joy at every pokemon center.
However, such an invention has not yet been made portable, so the medicine sold by stores is the next best thing. You can't really expect a store owner not to try and make money from the situation, and selling potions and status healers is a fairly profitable business strategy. | 59 | 85 |
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Can someone tell me why propositional logic is important and why Aristotelians and the Stoics spent so much time on it? | I have started reading Anthony Kenny’s A new History Of Western Philosophy, and am still getting the grasp of philosophy itself, and some of the disciplines of it I do not understand why it is important and why we would need to conclude an answer for it, such as propositional logic and what use it would be to know it.
Also, it seems that some disciplines are so ambiguous that after thousands of years have not come to a conclusion, so why argue on a topic that will never have a complete and definitive answer? | The use of logic is that it is the art of making inferences well. The use of making inferences well is that they only accomplish their function when they are made well, whereas the impair their function when made poorly. The use of inferences is that they're one of the basic elements of thinking. And the use of thinking is to understand and communicate about the world. | 12 | 22 |
ELI5 why "no excercise = tiredness" but "excercising = energy" | Simply put, the more active you are the more mitochondria your body produces. It's like a domino effect. The more you exercise, the body makes more mitochondria to make more energy. Just reply if you need a more in-depth answer. | 89 | 79 |
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What happens, on a molecular level, that leads to paper becoming soft after applying water to it? | Paper consists (mostly) of cellulose fibers, i.e. a polymer of glucose molecules. These glucose molecules have free hydroxyl groups, which can form hydrogen bonds to other molecules.
In dry paper, at least many of these hydrogen bonds are to neighbouring cellulose fibers, which stabilises the overall structure.
Water breaks up the hydrogen bonds between the cellulose fibers, so this stabilisation is lost. | 57 | 33 |
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ELI5: Do men’s and women’s hygiene products (shave gel, lotion, face wash) actually do different things for men or women, or is it a marketing thing? | Most of the ingredients are the same, though some manufacturers claim that their gendered products are tailored more towards the different areas that each gender tends to shave more.
The main difference in ingredients is the scent. Fragrances and oils can be incredibly expensive, which could go towards explaining some of the difference in price. We know women place more emphasis on the fragrance of a product than men (some men being happy to purchase without smelling the product at all).
At least when it comes to bathroom products, men and women discriminate on price differently. Men are more likely to take a cheaper product and see that product as equivalent. Women, on the other hand, are more likely to see a more expensive product as superior. Thus reducing price could be a good strategy for men's products but could actually lose you sales on women's.
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ELI5, What does "The medium is the message" mean ? |
Apparently a quote from [Marshall McLuhan](http://en.wikipedia.org/wiki/Marshall_McLuhan), that I remember from the Canadian Heritage thingy
I'm not sure I really get it
and since the internet didn't exist back when that guy said that
what does it mean for the internet/reddit/rage comics/memes/facebook/email/etc ?
what is the message conveyed by all these internet-derived medium ? | A perfect example to expand on E-Lucas' point.
During the 1960s Kennedy vs Nixon presidential debates polling showed that those watching the televised debates thought Kennedy would/should win (what with him being all young and vital) whilst those listening to the radio broadcasts of the same debates thought Nixon would/should win, presumably because his rhetoric was more impressive.
There's compounding factors at work as well, such as demographics of audiences. If Jimbob wants to meet someone who shares his love of pigeons he can put a personal ad in a pigeon fancying magazine and then this shared interest requirement doesn't need to be explicitly stated in the ad as it is implicitly stated by the medium.
Like wise, when you dump someone whether you do it face to face, by phone, email, fax or carrier pigeon will send strong signals to the dumpee about your attitude toward them.
It's not that the medium is the entire message, it's that it needs to be taken in to consideration because it can drastically impact how we receive the communicated content. | 44 | 42 |
Is it possible to create a language that is faster than the language it is written in? | Depending on your definition of "create a language", yes. If you make a compiler in a very slow, interpreted language (say python), the result will probably be a lot faster than the language it was made in. | 29 | 34 |
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[The Man in the High Castle] Why is the I Ching such a big thing in Japan-ruled America? | The I Ching is a Chinese work, not a Japanese work, and as far as I can tell, it never got hugely big in Japan, not even during Imperial Japan. Also, I'm pretty sure it was the Sino-Japanese War that helped kick off WWII, so I don't think Japanese people would want to promote a Chinese work. | Chinese culture has a vast influence on Japanese culture. Kanji is derived from Chinese writings. Shinto and Zen Buddhism was brought in by Chinese monks.
I-Ching would have been co-opted by the Japanese and "re-packaged" as a Japanese original work. | 13 | 19 |
ELI5: Why do public universities charge application fees? | Two things. First, someone has to be paid look over the applications. Second, it encourages only those with interest in the school to actually apply. If there was no application fee, they would likely see a much larger number of applications, many from people not really serious in their university. This would require a lot more staff to sort through and result in much more uncertainty that those accepted in will actually attend your university. | 11 | 16 |
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ELI5: Why do dogs live a shorter life than humans? | Let's say that a species is being successful if it can continually create viable offspring and replace it's individual organisms at least as fast as they are dying.
There's multiple paths to this in terms of reproductive strategies. One strategy, is to maximize the number of offspring, even if that reduces the chances of any particular individual surviving. An alternate strategy is a lower number of offspring, but taking more care to ensure their survival. Dogs are somewhere in the middle, while humans are basically at the far end of the "fewer offspring" side.
And following those different paths through evolution has resulted in significant biological differences. The human brain is significantly more capable than a dog's, but it also needs much more time to fully develop to the point where you get a human being capable of self preservation and successful reproduction.
A wolf (which dogs were bred from) is physically and mentally fit enough to reproduce and care for its offspring within a couple of years of its birth, can create a few litters of puppies, and then get old and die within a decade. Over that same 10 years, a human baby will still not even be developed enough to live on its own, much less create and care for a baby.
If you assume about 15 years for a human to develop enough to be in a position to successfully create and care for a child, and then another 15 years for them to care for their child to the point where that child can be independent, then that's 30 years. And that's just for one kid.
Before modern medicine came around, children died much more often, so the average mother might give birth to 5+ kids, so you're looking at being 35+ when your last child doesn't need you any longer. And 35 was a pretty typical life expectancy for much of the history of humanity. | 53 | 102 |
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ELI5: Why do we find people's misfortunes like tripping and falling funny? | Research has shown that the brain releases small amount of pleasing chemicals when a human sees something that fits their expectations. However, the brain releases even more pleasing chemicals when a human sees something that the exact opposite of their expectations. This is what we call "funny."
It is funny to see someone trip and fall because we all try so hard not to trip and fall all the time. | 16 | 17 |
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Would it be difficult to create computer vision that could distinguish between an open and closed soda can? | Hello. I am quite new to computer vision, but am planning on taking on a fairly ambitious project this summer. I am willing to put all of my time an effort in and am ready to learn, but I just wanted to get some more experienced opinions on whether this was a feasible project.
Essentially, I am trying to use computer vision to distinguish between two nearly identical objects. My primary question is: would it be possible to have computer vision distinguish between an open or a closed soda can (the only different being that the tab is open and you can see inside?). It would probably take a lot of training, but is it feasible?
If this is not possible, would it be possible for a CV program to distinguish between a white, paper cup that is empty versus filled with a colored liquid?
Thanks so much! | These would both be possible, as long as the differences are visible and you have ~thousands of training images or more.
The number of training images needed is kind of dependant on what kind of images you will be classifying later, in the product. If the product always sees the same kind of can from the same angle with the same lighting, you will get ok results with a few thousand training images. If your product must work on many kinds of cans and lighting and angles, you will need many more training images. | 15 | 17 |
[Marvel] Who did the Watcher make his oath to? | The Watcher swore an oath to only observe, never to intervene. But who did he swear it to? Does the Watcher have a boss who comes by and checks to make sure that he's only watching? Uatu seems to look for loopholes in the "just watching" oath all the time, so I don't think he made that oath just on his own or else he'd be fine breaking it with no consequences. | The oath of non-interference is a defining aspect of the culture of his people.
The Watchers are one of the first species to develop sentience after the birth of the universe, if not the first. After developing interstellar travel, the Watchers made an attempt to accelerate the development of a younger species. The primitive species was not ready to be responsible with the knowledge they were given, and quickly destroyed themselves with weapons of mass destruction.
This is the reason for the oath; to avoid repeating the mistake of causing harm with their good intentions. The make the oath to themselves and their peers, and their governing council is the body that enforces it.
The Watchers still gather knowledge with the intent to share and uplift others, but now their intent is to learn as much as they can before the death of the current universe and bestow the next universe at birth with all the accumulated wisdom of its predecessor. | 87 | 54 |
CMV: Kids that behave should be rewarded more than kids that misbehave | In middle school and even in highschool, there were always times where the students that were generally the rowdy or misbehaving type were rewarded for times when they would be on good behavior for a while. Often it would be candy or free homework passes, but it always bothered me because the students that never acted up and were always super polite and whatnot were never rewarded for their consistent good behavior.
I don't think the issue lies in the fact that the misbehaving kids would get rewarded, but I remember often being aggrevated because I would see other students getting rewarded while I wouldn't get anything for having consistently good behavior.
I understand this gives an incentive for the rowdy to become more behaved, but I think it just leaves out and frustrates the kids who never act up.
At the core, i think we need a better system for good behavior in middle and high school where the polite and respectful are rewarded just as much or more than the misbehaving who have a day of good behavior.
Edit: Thank you all for the contributions! Definitely have left with a changed view on things. | The point of the reward in this situation is not to reward good behavior by itself but to acknowledge a conscious change in behavior for the better. For a lot of those kids who were badly behaved, the change came because they were working hard at controlling their emotions, physical energy, giving attention, or doing other things that is outside of their normal range of behavior. It took conscious effort, it maybe made them feel uncomfortable, they had to use emotional control that for kids is very difficult to understand and implement.
Rewarding that behavior is *necessary* to help them develop those skills and deepen their emotional control. A kid who is very prone to just ditching things when they're too hard or lacks the will to dedicate themselves to a task has to push through a lot to finish reading a chapter or finishing a worksheet that tests them on a subject they don't enjoy. We want to encourage that behavior so we have to acknowledge that effort and make them feel good so they will want to do it again or feel capable of doing so without the reward.
Good kids already have those skills. They can already push through that pain/discomfort/emotional instability without assistance. It's a compliment to them but that equally means they don't need help to get over that bar. It's the same like if you're teaching two kids piano, you will necessarily have to praise every attempt and mangled effort at Twinkle Twinkle Little Star from the beginner but you will expect far more from a kid who has been playing 2 years and won't praise them for the same result.
They should be rewarded for doing similar tasks that stretch their abilities but the fact that the bar is low for one kid and high for another necessitates different responses and they shouldn't be rewarded in the same way for the same things. | 43 | 168 |
Are 1st and 2nd year PhD students usually expected to teach? Is being younger than the students you are teaching weird? | Hello,
I am currently an undergrad math student. I will be graduating with my bachelors at the age of 19 and will go for my PhD after that. Would the fact that I would still be 19 make the teaching aspect more difficult?
Thank you for your help. | Many universities have a policy or informally try to make sure those teaching have at least one degree higher than those they are teaching. Sometimes even terminal PhD programs will have students pick up an MA/MS along the way, or set a point of progress (x number of grad credits) before you can teach undergrads).
Try to avoid teaching immediately if you can. If you must teach, dress professionally and maybe try to make some sessions online if it is a predominantly face to face class. | 12 | 24 |
ELI5: Why does bathroom sink water seem to taste different than kitchen sink water? | Measure the temperature difference of the first 20 seconds of water. That can make a huge difference to taste. Ground water is often cooler than the extra house piping needed to reach the bathroom.
Aerators often found in bathroom taps to prevent splashing change the taste too (and get gross, they need removing & cleaning).
Your kitchen faucet probably cost twice as much as the bathroom fitting, and is more likely to use ceramic valves and noble metals that don't impart a bad taste. As the most frequently used faucet it will hold fresher water too. | 383 | 535 |
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ELI5: Why do humans seek familiarity like staying in the same house or bed but get bored of performing the same task over and over? | I think it contradicts how the mind works | As just stated, Safety is first, so comfort and familiar environment can last a long time until the person feels they can attain that same safety elsewhere. When it comes to tasks however, purpose and passion come in. To be useful or valuable, the brain wants to do something meaningful, creative, successful, etc., which usually means a variety. Some people do find their favorite passion and do the same thing for 20 years, but that’s rare to find. | 47 | 103 |
I have little respect for anyone who smokes weed every day. CMV | edit: I think my view has been changed... I still think there's a problem with anyone who relies on the drug, but I also realise this is the same as alcohol. There are people who do, and it is a problem. But because you smoke every day doesn't immediately make you addicted.
_____
I feel like anyone who needs to smoke weed that often has developed a reliance on a drug which they don't acknowledge as a problem. It isn't any different to being an alcoholic and needing a drink every day, except society recognises this as a legitimate problem.
I think weed makes you lazy and complacent and to smoke every day just implies you not only have a mental addiction, or reliance, but that you aren't making the most of yourself and your time.
I have no problem with weed being smoked every so often, socially. But the people I know who can't go a day, or can't go to bed at night, without a joint... there's just something not right there.
Change my view. | Let's say there's a person for whom you currently have lots of respect. One day, you find out that this person smokes weed every day, and had been doing so all along. Would you immediately lose all respect for that person? | 67 | 65 |
why is momentum conserved but not kinetic energy? | and how's it reflected in their respective definitions: when i look at mv and 1/2mv squared i don't see something obvious except that i guess the latter can't be negative? anyway, just curious about this since taking physics forever ago. | Energy is conserved, but it can be converted between different forms of energy.
For instance, you can lift a sled up a ramp, using chemical energy from your food to do work on the sled, and adding potential energy from gravity, and then release the sled, converting potential energy into kinetic energy in the motion of the sled, and thermal kinetic energy from friction (or kinetic energy in the form of sound, energy added to the air around the sled, etc.). | 41 | 51 |
What if persons, seen as mentally ill, are in fact perceiving the "real reality"? | Because mental health is determined by how the majority of people "is". But what if the mentally ill minority, are those experiencing reality? | Partly the answer will depend on what "mentally ill" specifically means-- after all, we now recognize many mental disorders, of some considerable variety. To take just two major ones, schizophrenia (itself found in many forms) and major depression are quite different, and involve experiencing self and world differently.
Our evaluation of the proposal, accordingly, will vary. For instance, there is a view called "depressive realism" which posits that depressed people make more accurate inference about certain things (such as one's own abilities and competence). Or, more broadly, we could suggest that depressed people are accurately seeing that the world is a hopeless and ultimately tragic place.
On the other hand, if we're talking about, e.g., paranoid schizophrenia, the idea that the patient sees more accurately would presumably involve his picking up on real conspiracies that other people don't catch. Or perhaps the suggestion could be that what *we take* to be mental disorder is simply perceiving some disturbing fact-- perhaps there really are alien intelligences speaking to some people telepathically, and we say they're just "hearing voices" and label them as mentally ill.
So a lot depends on the details, and we'd have to consider in each case just what our reason is for thinking any of these scenarios are plausible. | 83 | 143 |
ELI5 why does fiber cause gas? | Fiber refers to carbohydrates, such as cellulose, that aren't digestible by humans, and pass through the digestive tract relatively unaffected, at least on a molecular level. This contributes to fullness / satiety, and it helps make sure that there's solid matter moving through the GI tract, which helps keep you regular. However, many types of bacteria in the intestines do have the ability to break down these carbohydrates. The end products of these processes are generally simple compounds such as water, methane gas, and carbon dioxide. And all that gas building up in the intestines builds up until the body has a release. | 46 | 107 |
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Why don't they make 3D printers like such? | First, you have a potentially good and profitable idea...keep that in mind.
3D printing is very useful, but not applicable everywhere, because of inherent advantages and disadvantages. It's very useful, for instance, when a one-off item must be quickly designed and fabricated. It's also good for prototyping new concepts.
Compared to more traditional manufacturing methods, however, it isn't typically cost-effective at high-volume runs. So in this case, toys can be molded out of plastic using these traditional methods, and run in high volumes. The result are toys that are cheaper than what one could print at home (look at current ABS and PLA filament pricing if you don't believe me), and more complex toys can be made this way.
As far as the complexity of current 3D printers, well, they require a certain inherent complexity to function. Think about what they are required to do: three axes of precise, controlled movement, plus controlled extrusion, of a precise diameter, to produce strong, dimensionally stable parts. That's quite a feat. | 13 | 30 |
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[ELI5] How do scientists figure out how much protein, carbs, vitamins, etc. are in a food? | Do they just test the food directly, or do they test your blood afterwards to see how much you've changed from a baseline? How about vitamin pills-- do they ever do a blood test to determine how much of the vitamins gets absorbed? | Ok, so first we'll address proteins, carbs, and fats. Fats, which are like butter, oil, or the white stuff around a steak, can't combine with water. So, we weigh how much the food weighs at first, then we use a solution called "ether," which is kind of like scientist's dawn, to wash away the fat from the food. Then we weigh the food again & figure out how much is left. Then we subtract how much is left to how much we started with & that gives us how much fat is in the food.
Carbs & proteins are trickier since they are both water soluble. For proteins, we can't directly measure proteins like we can for fat & instead measure a substance called nitrogen, which is another pure element like oxygen & carbon. We measure nitrogen because all proteins contain nitrogen. Now, to find the amount of nitrogen in a food, we mix the food with sulfuric acid, which is like the acid that we see on cartoons that eats almost everything it touches. This sulfuric acid will make ammonia, which is that smell made by cleaning products. We then measure the amount of ammonia made & that tells as how much nitrogen and, therefore, protein is in the food.
Carbs are fun to measure because we essentially put the food sample into a small washing machine & add different detergents to figure out how many carbs are in the food. Like when finding fat, we measure how much food we started with, then how much food we ended with, subject one from the other & find out how much of the food was carbs. (DO NOT PUT FOOD IN THE WASHING MACHINE!)
For vitamins & minerals, there are individual different methods for each vitamin & mineral. For minerals, we can either do wet chemistries or atomic absorption spectroscopy (AAS). Wet chemistries which is we a scientist will add different solutions to the food till a chemical reaction occurs, like a change of color or a formation of a solid in a liquid solution. AAS is when we put the ash, or burnt up remains of the food, into water. We then fire a beam at the water & measure the light bounced out of the water, kind of like a prism. The color & amount of the light reflects what type & how much of mineral is present.
For vitamins, every vitamin is a bit different. Often times, though, we compare a solution with a known certain of the vitamin to the food solution & calculate the difference between the two. Ask me when you're 10 for specifics.
We don't test the blood after we eat a food because there are so many differences between people that it would not tell us how much of something is actually in a food.
For vitamin pills, we do sometimes due "bioavailability" studies, which essentially looks at how easily a pill is used by the body instead of just getting pooped out again.
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ELI5: What is abstraction in computer science? | Computers do lots of really complex things, right? In order to make them simple for people to understand and work with, we provide *abstractions* of them.
Let's say we want to have a linked list of numbers. You could, every time you want to add an element to that list, allocate the memory, put the value in your new data structure, find the end of the list and then update that to point at your new element. You could, every time you want to access the *N*th item, loop through all the elements of that list until you've gone through *N* and then use that value.
This is not only a lot of typing, it's error prone & all that duplication makes it hard to modify your code if, for example, you wanted to replace your linked list with a more efficient skip list or something. What do you do?
You write some functions that give you an `add_element()` function and a `get_nth_element()` function. You can use these when working on a list *without caring how it works under the hood*. This leaves you free to use linked lists without massive code duplication, easily fix bugs or even change how it's implemented.
Providing that interface over a complex underlying implementation is an **abstraction**. Abstractions are everywhere. When you open a web page, you're not telling the computer how many volts to shoot across your ethernet cable, you're working on top of a bunch of layers of abstraction that give you a simplified way of doing a complex task. | 11 | 16 |
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ELI5: Why is violence, murder and death so widely accepted in movies/TV/Video games, while sex and nudity is considered taboo? | That's mainly in puritan societies that are heavily influenced by religious entities. In many European movies nudity is not such a taboo.
Violence is a reflection of a society that's focused on war and guns, where physical strength is important to subdue "enemies".
Since the US has a huge influence over global entertainment you end up with a skewed view.
Go check French movies and Brazilian TV. Nudity is not a big deal there. | 174 | 180 |
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Correlations With Wealth? | I'm looking for statistics on things that correlate with wealth. Even [spurious correlations](http://tylervigen.com/spurious-correlations) will do, not just things that might imply causation. Any help would be appreciated. | There are plenty of educational outcomes that correlate with socio-economic status. You could probably think of anything and find a study that confirms it: literacy, standardized test scores, self-concept, enjoyment of school, graduation rates ...
Would anything like that be helpful? | 10 | 28 |
How is biometric authentication not practically the same as using the same password for everything? | Sure it is a good password so it can't practically be guessed, but in the event of a database leak with all our fingerprints they are no longer secure and can no longer be used, ever really. | Biometrics, although intended as an authentication method, are significantly different than passwords.
1. Biometrics can be forged - forging a password means you know it
2. #1 is because a biometric is _something you have_, while a password is _something you know_. Ideally one would use them together in a 2-factor authentication system
3. Passwords are secret data. Algorithms can manipulate (secret) data to realise useful security properties like confidentiality and authentication. However, passwords are intended to be remembered by humans, severely compromising their entropy, and thus their usefulness to said algorithms
4. Biometrics are _measures_ of the human body, and thus are susceptible to measurement errors. Additionally, they are not secret, aka _confidential_; you show your retina to everyone you meet every day, your fingerprints are all over your desk, the cafeteria, the bottle you just picked up, etc.
5. To satisfy the property that a biometric must authenticate a person in the face of measurement errors, it must be suitably _unique_. Corollary is, of course, that you aren't able to change it often, or at all.
In a general context, you are thus correct: since a biometric represents something you have, and you can't alter it very easily (although that's the very thing cosmetic surgery is fighting against), it would be equivalent to using the same password for every purpose. This goes against the general guideline that instruct us to not use the same password for multiple services, because that leads to a centralised failure mode: if one of these services is compromised, your account in all the rest is also compromised.
Biometrics work better in local contexts. A _local context_ is where there is an available "honest" system; no men-in-the-middle, possibly physically isolated, etc. Biometrics are good at authenticating a human body _locally_, but that is also where passwords are just as good: it is very common to use a generic smartcard or a 4-digit PIN to enter your workplace. | 18 | 22 |
New to Econ, is socialism rejected by mainstream economics? | Like the title says, I just started looking into to Econ for the first time and I was curious: as socialist economics are described as heterodox, does that mean that mainstream academic consensus is that socialist economics don’t work? I understand the rejection of Central planning given its well documented failures, but it seems like market socialism is rejected as well, at least from what I’ve gathered from posts on this sub and bad econ.
Does this mean that socialist economic theory is just considered to be wrong by orthodox economists, or am I misunderstanding something? As someone new to the subject, any and all help is appreciated. | Terms like socialism, capitalism, etc. are generally not particularly well regarded because they are imprecise to the point of saying nothing at all. So in that regard, it's neither accepted nor rejected.
In practice there will always be situations where more or less state intervention leads to more desirable outcomes and different ownership structures have different benefits, broad statements make little sense here. | 175 | 41 |
ELI5: How does the human body suddenly become allergic to a certain type of food, after years of eating it without any problems? | A relative of mine used to eat shrimps, crabs etc. almost weekly for years. Now he's suddenly allergic to that type of food and can't eat anything related to that without suffering from allergic reactions.
Why and how does this happen? | I was hoping you'd include shrimp in the question. Shellfish are somewhat of a special case. They're basically living filters, and they soak up the animals and chemicals around them. There are very few people with a genuine allergy to shellfish; rather, they're allergic to what the shellfish have been eating.
This is why you might eat shrimp for 30 years and suddenly blow up like a balloon, out of the blue. Chances are good that if he ate shrimp from a different location, he would be just fine. However, once you experience a negative reaction to a food, it's very easy to get caught up in the psychological response associated with getting sick. He probably has no interest in eating shrimp at this point and would manage to feel genuinely sick even if he isn't really allergic. | 885 | 1,132 |
What gives rise to the right-hand rule in electric currents? | Why does the magnetic field wrap clockwise around a traveling electron? | I wrote this in response to a similar question a week ago:
>A magnetic field is not really a vector, like the electric field, it's really a bivector, pseudo-vector, or 2-form. As a vector has a direction, a 2-form lives in a plane. The thing is, in 3 dimensions, there are exactly as many dimensions (x, y, z) as there are planes (x-y, y-z, z-x). When we say a magnetic field is pointing in the z-direction, it's actually a bivector in the x-y plane. You can get the direction of a vector associated to a bivector by taking the vector product of 2 vectors in the associated plane.
>So essentially, the cross product appears as an artifact of us pretending that the magnetic field is a vector instead of a bi-vector.
>In d space dimensions, while an electric field would always have d components, a magnetic field would have d(d-1)/2, so in general we couldn't talk about the "direction" of a magnetic field. | 10 | 22 |
ELI5: What is happening when our eyes "glaze" over? | Check out Brain Games on Netflix, it has a lot of info on these types of things.
Your brain uses 30% of its energy processing vision. When your eyes gloss over, your brain has realized what you are looking at isn't needed information in conjunction with what you are thinking about and has reallocated some of that 30% energy to another thought process. Temporarily. | 187 | 373 |
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ELI5: What EXACTLY is a 403 (b) | I am being offered a retirement plan for the first time ever in my working life. I know it would be a good thing to do but I have zero idea how it all actually works. What happens to the money after I put it in? How and when do I get it out? What happens if I switch jobs? TIA for your help! | 403(b) is just a 401(k) for nonprofit employers, so you can find a lot more about 401ks on the internet.
Your employer contributes money into an investment account, and you can contribute too by having the money deducted from your paycheck. For a traditional 403b this money doesn’t show up on your tax forms as income, so it’s tax-free going in.
When you retire you can pull out the money — plus the investment returns — to live on. You do pay income tax on it when you pull it out, but since most people have a lower cost of living in retirement, the tax rate will be less.
At the very least don’t pass up the employer contribution, that’s free money, but usually it makes sense to max out the employee contribution if you can.
While the money is in there, you usually have a lot of freedom to decide how it gets invested, but you’re stuck with the investment company your employer chose.
If you switch jobs, the 403b is still your money. You can keep it in there, or “roll it over” into an IRA, an individual retirement account, which works basically the same way except it’s not tied to any employer. Generally you’ll get a new 403b or 401k for each new employer, so if you switch jobs a lot the rollover IRA simplifies things and gives you the freedom to choose your own investment company if you like. | 39 | 38 |
ELI5:How did two different forms of genitalia evolve? What is the advantage of having males and females? | I've always wondered how two things so complicated were created to work together and what advantage there is to prevent the organism from mating with half the population? | There are thought to be two main reasons why there are two genders, the first is the more commonly known reason, the sharing and mixing of genetic material. If two individuals combine their genetic material they can allow for more variation, and try more possibilities, making it easier and faster to adapt and evolve in the long term, where as if any two individuals can mate it promites inbreeding and less diversity, as the nearest viable mate is normally a relative. It's also a great advantage if there are two competing groups each with different, advantageous mutations - by mating, members othe two groups can give their offpsring *both* mutations, instead of the mutations having to compete, and one eventually dying out and being lost.
The main reason why there are only two genders in most (arguably all) animal species is likely that adding extra genders does not improve the efficiency of the process - it's a lot harder to gather together three individuals, all ready to mate and all of different genders, where are the increased genetic diversity it offers is very limited - you're adding 50% more new genetic material (less when you consider that the third individual probably shares a lot of genes with at least one of the others), but making the process drastically harder. It could have been possible to evolve multiple genders which each needed only one other gender to reproduce with, but this requires additional sexual organs, and would naturally tend to lead to asexual (reproducing without any help) or hermaphroditic (both genders at once, and able to mate with any other individual) species.
Another factor which probably played a large role is the difficulty of evolving a third gender - evolution works in tiny increments, and each change must be beneficial, or come with other beneficial changes, to be passed on often enough that it spreads through the population, meaning that it would be extremely difficult for extra genders to evolve in large, complex organisms that reproduce in the manner we do.
Finally, the other reason why we think there are two genders (and not more or none), is mitochonrial DNA, a type of genetic material found outside the nucleus of the cell, in the mitochondria (thought to have been added to cells around 2 billion years ago by bacterial infections), which also produce energy for the cell. This genetic material has the ability to copy itself very rapidly. Mitochondrial DNA may in fact be responsible for making extra genders a disadvantage but at least two genders neccessary, as any mutation in the mitochondrial DNA can be passed on far more often than mutations in the nuclear DNA, meaning that if an individual picked up a very harmful trait it could rapidly destroy the whole species - male and female genders are thought to have evolved as a stopgap to prevent this, as mitochondrial DNA is only inherited from the mother and not the father (limiting how much of it is passed on), preventing it from spreading out of control and limiting the ability of the individual with the harmful mutation to flood their offspring with the same mutations.
It is worth noting however, that some scientists argue that some types of shrimp and ants have what can be viewed as extra genders, and funghi can have as many as 36,000 (interestingly, funghi do not exchange mitochondrial DNA, which may be why they are able to have so many genders without suffering disasterous effects). | 18 | 30 |
CMV: The European Union needs to be deeper. Not wider. | The citizenry of the European Union would be better served by EU institutions that were:
1. More active
2. More democratically accountable.
We can see how this played out during the economic crisis, for example. And also in terms of the defense and foreign policy issue.
In these cases, we've insufficient coordination between the member states on key issues such as financial regulation, foreign policy, or military coordination.
Meanwhile, the institutions of the Union are so ineffective that they can essentially be vetoed by one or two member states acting in their own domestic interests. Or even sub-national interests.
Meanwhile, the only EU institution that is directly elected is the parliament. It means that the other institutions do not have the actually have the necessary legitimacy or gravitas to challenge the lack of coordination that arises among member states from time to time.
In addition, several of the member states that joined since 2004 are openly either corrupt or non-democratic, and also are essentially financial black-holes into which our subsidy funds keep disappearing.
This ranges from Hungary, where the regime is elected on antisemetic fear-mongering, and openly makes statements about preferring to be an "iliberal democracy" (Like Erdogan's Turkey basically), to Poland, where they've undone judicial branch independence, to Romania where they've been trying to pass a law legalizing corruption in amounts less than 50,000 EUR (this amount buys a house in romania. Or two luxury cars).
Going forward, it'll be difficult to get some actually functional and democratically accountable EU institutions built if it's all going to depend on the votes of member-state regimes instead of the votes of people, and half of the member-states in question are corrupt non-democracies with a direct personal interest in preventing the development of democracy and transparency.
What I propose that that sub-union blocs form treaties amongst themselves. Such as the Benelux Union and the Scandinavian Union, which already exist.
CMV
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> *This is a footnote from the CMV moderators. We'd like to remind you of a couple of things. Firstly, please* ***[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)****! Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | Most important role of EU is to ensure peace in the region. By ensuring wide membership base and economic depend we prevent another European great war. Poor countries are more susceptible to extreme moments but also benefit the most from EU.
I agree we should have deeper union but there are valid reasons for width. Other reasons include that by "helping and guiding" poor countries we rise prosperity of the whole region. We create new markets (customers) and therefore help the rich members. | 20 | 108 |
[Superhero powers] What would be a good defensive/support powerset that isn't a waste? | I write for therapeutic therapy, so I'm not that good, but I have a group of heroes with powers and I don't want to give all of them strong offensive powers. Out of a group of 5, two have a strong offensive set, one is defense/offense, one is support. The last one can't be offensive but I don't want it to be weak or make it seem she is sidelined. Defense/offensive is fine, if it's clearly stacked on the defense side though, or a support/offense powerset. | intangiblity is great for a defense/utility power, and can be easily suited to almost any group, and it has some easy power limiters too if you want(can go through living things, cant use it to fly, blocked by X material, just to list some examples) | 17 | 16 |
[Harry Potter] What are the Room of Requirement's limitations? | The room was able to add a route out of the castle and in to hogsmeade for Neville Longbottom and co, so what if I walked pasted to with a desperate need to get to somewhere in Spain?
How big can it get, what are the limits to what it can create, etc? | I think the more magic and difficulty of accomplishing a task, the room requires you to have an equal amount of need for it. So to get to spain you would probably REALLY need to.
Also it might cheat with things like that.
Need to get to spain? Here's a broom and a map.
Need to get laid? it doesn't provide a ho but a book on how to woo women and the RoR turns into a gym. | 37 | 30 |
How do genetics show invasion took place in history? | Quite often I see genetic changes in populations viewed as invasion etc
Can you differentiate using genetics between a population that is undergoing invasion compared to say becoming multi-ethnic/cultural?
Or is more than genetic evidence required to make this conclusion?
Thanks for any help | >Can you differentiate using genetics between a population that is undergoing invasion compared to say becoming multi-ethnic/cultural?
Yes. For example, if most of the old Y-chromosome lineages suddenly disappear and are replaced by lineages from another region, it's likely that invaders came in and killed off most of the men (or at least prevented them from reproducing). | 18 | 29 |
ELI5: Why is there such a clear average difference in the type of jobs Middle Eastern immigrants tend to go for vs Mexican? (i.e: Taxi Driving vs Landscaping) | Imagine that you're an immigrant in a new country. You don't have any close friends or family there, and other than a few vague connections with casual acquaintances, you're pretty much on your own. You'd like to get a job - that might even be why you made the trip in the first place - but you don't speak much of the local language, and the community isn't really set up to support you.
Then, one day, you meet someone else from the same hometown as you! He's sympathetic to your plight, having been in a similar situation when he first arrived. "I'll tell you what," the man says, "I have a buddy who could use an extra pair of hands on his crew. The pay isn't great, but at least it would be something... and you'd be working with people you can talk to."
You end up taking a job with this group. It's not what you'd hoped for, exactly, but it keeps you from starving. Eventually, you start making a little bit more, and you begin to feel comfortable with your surroundings. You don't get as much free time as you'd like, and it's difficult to make new friends, but you've started to fit in with your workmates and their families. You might even move to a different section of town to be closer to them, which makes both your job and your personal life a little bit more convenient. Besides... as difficult as it is to accept, you've noticed that some of the town's other residents - people who don't understand what you've been through, and with whom you can't easily communicate - look down on you for some reason, and it's nice to be with folks who accept you for yourself.
Years might go by, or maybe only months, but eventually, you encounter someone else from your home country. They're only recently arrived, and they remind you a bit of yourself. "I'll tell you what," you say to them, "I have a buddy who could use an extra pair of hands on his crew..."
People tend to gravitate toward groups with which they feel comfortable. It makes finding employment (and friends) easier, but it also results in a kind of stagnation. Think of it like this: If an English-speaking person moved to a place where everybody spoke something else, they'd probably wind up in a job that was stereotypically held by English-speakers. It's not a rule that applies to everyone, of course, but when presented with the opportunity, people tend to take the path of least resistance. That path, particularly for immigrants, usually involves working alongside folks with similar backgrounds and languages. | 33 | 18 |
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If the sun converts hydrogen to helium where does it get the neutrons to do so? | I'm a pretty sciency guy but my 12 year old daughter has stumped me with a few question.
If the sun starts out as a dense ball of hydrogen (one proton and one electron) and uses nuclear fusion to convert it into helium (2 protons, 2 neutrons, 2 electrons), where does it get the neutrons?
Also if the atoms in the sun are a plasma (stripped of their electrons) where do the electrons go? Does that mean the sun is a giant positively charged object if it has no electrons?
Daddy doesn't know everything. | Two atoms of hydrogen are combined to create helium-4 and energy in several steps:
1. Two protons combine to form a deuterium atom (hydrogen atom with one neutron and one proton), a positron (similar to electron, but with a positive charge) and a neutrino.
2. A proton and a deuterium atom combine to form a helium-3 atom (two protons with one neutron) and a gamma ray.
3. Two helium-3 atoms combine to form a helium-4 atom (two protons and two neutrons) and two protons.
These reactions account for 85 percent of the sun's energy. The remaining 15 percent comes from the following reactions:
1. A helium-3 atom and a helium-4 atom combine to form a beryllium-7 (four protons and three neutrons) and a gamma ray.
2. A beryllium-7 atom captures an electron to become lithium-7 atom (three protons and four neutrons) and a neutrino.
3. The lithium-7 combines with a proton to form two helium-4 atoms. | 272 | 567 |
What makes a gene dominant or recessive? | What is the difference between a dominant or recessive gene? I know that dominant genes prevail over recessive ones and this is also the stuff I find on the internet. But I can't find an explanation of what makes a specific gene prevail over other ones in the fist place. | It depends on the details of what the gene does and how each allele (different version of the gene) works or doesn't work.
For example, lactose intolerance happens when _neither_ of your two genes for making lactase are functional in adulthood, so a single lactase-persistence allele will be dominant over a normal lactase-only-in-childhood allele. Or say you have a mutation in your ACE receptor that stops SARS-CoV-2 from binding: this COVID immunity allele would be _recessive_, because one copy of a normal ACE receptor would be enough to let the virus in.
Then there are other situations, like making red pigments to color a flower petal, where having one allele just gives an intermediate phenotype (pink) compared to 0 (white) or 2 (red). | 65 | 124 |
[Skyrim] Who are the hostile mages that hide out in caves and fortresses? Are they just bandits using magic? | [People like these dudes](https://www.youtube.com/watch?v=O2qDZJVzRxQ). | Typically they're doing research that respectable institutions won't tolerate for ethical or practical reasons, or not skilful enough to gain recognition in mainstream circles, or lending their powers to some kind of criminal enterprise. You can live pretty comfortably even in a cave with magic, so it's not that uncommon. | 71 | 40 |
What is the exact relation between mass and electromagnetic charge in the scope of modern QFT? | Years ago I actually had several courses on GR and QFT (alas I forget most of it over the years) but why is it that all electromagnetically charged particles are massive. Is this a direct consequence of the symmetry breaking introduced by the Higgs field?
I speak Lagrangians and Hamiltonians, you don't have to be gentle. | The mass and electric charge of a given particle* are independent numbers, arising from independent considerations. In the context of QFT, an elementary particle is something that transforms under an irreducible representation of the Poincare group. Such a representation turns out to be completely specified by two numbers: a non-negative real number (mass), and a non-negative half-integer (spin). Electric charge, on the other hand, is a number measuring how much a field's complex phase changes under a certain U(1) transformation, which is an internal symmetry not related to the Poincare group.
When you write the Lagrangian for a general particle, you include the mass and electric charge as free parameters (that are then fixed by experiment). In principle you could make the mass zero and charge non-zero and nothing would go wrong. It just happens that in our universe there doesn't seem to be any massless charged particles. We can be quite sure of this - if such a particle existed, it would be very easy to produce and detect, and massive charged particles like the electron would no longer be stable.
\*Although interestingly, the masses of particles in our universe depend crucially on the Higgs being uncharged. The photon is massless precisely because the Higgs is uncharged, and the Yukawa interactions that give rise to the masses of other particles would not be possible if the Higgs were charged. But there is no relation between a particle's mass and *its own* charge. | 26 | 38 |
Does it hurt to have publications outside of your field of study? | I am a recent graduate working as a research assistant under two PIs. One (PI A) works in my field of study, the other (PI B) does not. By the end of my tenure here I should have two or more papers out under PI A, but I also may have one or two from under PI B.
Does it make a difference if some papers I am published on are not in the field I intend to go to grad school in? Or is it a more papers is better regardless of the field situation? | It absolutely does not hurt. Will it help in the short term in applying to grad schools? It probably depends how far apart the fields are. If they're, say, biology and physics, I'd say it's still a net plus to have the extra article. If, on the other hand, they're history and chemistry, then the practical benefits are not so clear. It's not something that'll get you into graduate school, but it might break a tie.
In the long term, this is surely a good thing. The more different ways you have of looking at the world, the better off you are in any field of study. | 23 | 15 |
How do fish in the ocean not get dehydrated? | Humans can't drink salt water because it has so much salt right? So how do fish stay hydrated if they never access to fresh water? | First, some background. Water flows from areas where there's not much dissolved (low salinity), to areas where there's a lot of stuff dissolved (high salinity). This is called osmosis. Dissolved things (like salt) flow in the opposite direction, from high to low concentration.
Hagfish have blood at the same salinity as seawater, so they don't have to worry about water loss due to osmosis.
Sharks and stingrays have low concentrations of salt in the body (similar to humans and bony fish), but they have high concentrations of urea and TMAO in the fluids. The total amount of "stuff" in the fluid is the same as seawater, it's just that most of it is urea instead of salt. So they don't have to worry about water leaving their body. They _do_have to work to pump out extra salt ions that try to enter their body.
Bony fish have blood that is less salty than seawater (just like humans-this is why if you are stranded on a raft you should try drinking fish blood instead of seawater). So water is constantly trying to leave their body and salt is constantly trying to get in. The fish make up for this by drinking water and excreting the extra salt ions out of their kidneys and gills. You can't just drink seawater because your body isn't good enough at getting rid of the extra salt. But marine fish are better at pumping out the salt, so they can get their water through seawater (and food) without being dehydrated. Some land animals (eg, cats) are good enough at excreting surplus salt that they can actually drink seawater without becoming dehydrated. | 37 | 24 |
I think weight loss is more complex than calories in, calories out. CMV | I think it comes down to the kind of food you eat and how much of it you eat.
Sam Feltham ate over 5,000 calories per day for 21 days. His diet consisted of eggs, fish, meat, nuts and green vegetables. After calculating his BMR he estimated he'd put on 13 pounds by the calories in/calories out, but only put on 2.8 at the end of 21 days. His daily exercise routine did not change. Why did he not gain 13 pounds? Why did he only gain 2.8 if calories in/calories out is how simple weight loss is?
Mark Haub lived on a diet of basically only junk food for two months and lost 27 pounds. Twinkies, Doritos, hostess cakes, etc. However, he restricted his diet to only 1,800 calories per day. If he would have eaten 5,000+ calories per day of food like this, do you think he would have still lost 27 pounds?
I think calories in/calories out oversimplifies it. Eating natural foods like Sam Feltham did don't cause as much weight gain as junk food. | One thing you need to understand about "calories" is that (human) nutrition actually uses fairly inaccurate figures, from a real-world-effects standpoint. The number that you see in the nutrition label is determined by how much energy can be taken out by completely burning it in a furnace. As an extreme example of how this can be a bad measurement, sugar and sawdust would show (approximately) the same calories by that test, despite sawdust being completely indigestible.
Whole and uncooked foods fare better in that system, as people can not digest them as fully or as easily.
Calories in/out works, as long as you account for the losses due to some being indigestible and the metabolic costs of digesting the food. | 31 | 23 |
CMV: Cows are Technology | Not just cows, but most domesticated animals, corn, squash, and most other fruits and vegetables can be considered technology and a human invention in the same way that my phone is.
All of these things have been modified from their original natural forms in significant ways.
The fact that they are living does not make a distinction. If corn didn't exist and we invented it tomorrow by genetically modifying grass in a lab it would not only be considered technology but would be patentable.
The fact that they were created by selecteive breeding does not make for a distinction here either. Under that reasoning a lot of computer algorithms would not count as technology either, as they were developed by itterative artificial selection in a similar way.
There is no reason to think of domesticated plants and animals as being any less a technological invention than a car.
Edit: the best point I've seen made here so far is that technology is knowledge, not the thing itself. Therefore cows (plural) are technology but cow (singular) isn't. By the same note cars are a technology, but your car isn't, because the technology is the understanding. This is different than how I think people colloquially think of technology, but is a robust definition. It does however mean that cows are still technology, in the same way as all other technological understanding, if anyone wants to hash that out. | >All of these things have been modified from their original natural forms in significant ways.
I think the key part is that not every individual object was altered or "built" - their breeding is definitely "technology", but the process is not.
I think what you're saying is akin to saying that "water is technology because it comes out of faucets". | 21 | 59 |
ELI5: Why do tinted windows almost look like a grid when you wear sunglasses? | Polarization. Simply put: Sunglasses with polarized lenses align the light in one direction. The tint is an imperfect film that has certain polarizing effects on light as well. When you have the shades on, you’re able to see the alignment of the tinted application.
Try this with cheap shades. You won’t see anything. Any sunglasses with polarized lenses will show off other polarized items. Even the aftermarket screen protectors on some phones are polarized, you’ll see the pattern as well. | 96 | 184 |
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ELI5: why do we lose weight more easily when we drink lots of water? | 1. Your stomach has stretch receptors that tell your brain you are full. If you drink a lot of water, your stomach is streched out by a 0 calorie drink rather than a high calorie food. That's partly why eating a giant low calorie salad makes you feel as full as a small high calorie baked good. There are other things that contribute to fullness, but the stretch receptors are an important one.
2. If you drink cold water, your body has to burn calories to warm it up to body temperature.
3. You drink water instead of other high calorie beverages. You will swap out water for soda, juice, etc. That keeps those empty calories off.
4. Your kidneys have to burn more calories to get rid of all the extra water you drank.
5. Water is an important part of many calorie burning chemical reactions in your body. If you don't have enough water, your body stops the less necessary reactions to conserve water. | 380 | 417 |
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CMV: I'm going to vandalize my neighbor's car | **The two key points of my view:**
- This is a good idea
- This is a rational idea
**My view (just going to put this in bullet point form, think it's easier to read that way):**
- I live in a town home community, that has a shared parking lot
- I know the owner of the car I'm going to vandalize lives there, but I don't know what home he lives in
- Neighbor got a new car alarm around December '16
- Car alarm goes off multiple times between 1am - 4am. Every time I've looked outside, I can't see any activity going around near the neighbor's car. I'm guessing it's a racoon or cat making the car alarm go off; possibly wind.
- I'm actually a very deep sleeper, so I'm not used to being woken up by outside noises.
- I tried wearing earplugs at night to not be woken up, but they didn't help.
- I kept a log of how often the alarm was going off, to make sure I wasn't exaggerating how often it is occurring. After one month, I logged a total of 23 occurrences, and 11 distinct days it had gone off.
- The issue is affecting my performance at work. I need to concentrate to perform complex analytical activities, and being sleep deprived makes my tasks take longer than usual. My mood has also been impacted at work. I've never snapped at anyone or anything, but there have been a few occasions where I appeared visibly annoyed when someone was asking me questions or for help.
- I have left three notes on the car explaining the car alarm situation. The first two were very polite. I explained that I had all my windows closed and was wearing earplugs, but despite this the car alarm was still waking me up. After no change in the car alarm situation, the 3rd note was very hostile. I explained that if he didn't do something about the car alarm situation, I am going to "fuck up" his car.
- Despite the 3rd note, there has been no change after 2 weeks.
- My next best option is to slash the tires of the vehicle and break the windows. I've ordered an emergency glass breaking tool for the windows, and will use a sturdy knife for the tires.
- I think I can do the whole thing in less than a minute without making much noise, so I'm not likely to get caught. I will wait for two more weeks, so that it will be four weeks since the hostile note, reducing the chance the neighbor is watching the car waiting for me to go do something to it.
- Even if I do get caught, I don't have any previous criminal issues, and it's just vandalism. So I won't do any jail time, just fines and possibly community service.
- I considered notifying the community management and/or the police, however then they and/or the neighbor would know who lodged the complaint. If the complaint doesn't resolve the situation, I then couldn't follow through with the vandalism as it'd be obvious that it was me.
- I can't think of a more effective action I can do that will make the neighbor remove the car alarm, or adjust its sensitivity.
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> *This is a footnote from the CMV moderators. We'd like to remind you of a couple of things. Firstly, please* ***[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)****! Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | Ask others if they have noticed the issue. If it is as bad as you say, then surely the answer will be 'yes'. Go with two or three others as a group to complain to the property manager.
They will almost certainly listen to your complaint and take action. They probably have a reference that links the license plate number to contact information for the owner of the vehicle. They can call and threaten to tow the vehicle, for example.
If the property manager won't listen, file a police report. There are noise ordinances that make this kind of situation illegal. The police can certainly find the owner of the car, and take appropriate action.
Vandalism inflicts unnecessary financial harm. It reverses you from 'victim' to 'aggressor'. You will lose all grounds for legitimate recourse. Seeing a vandalized car will create fear in your neighbors, who will wonder whether they will be targeted. It's also conceivable that the owner of the problematic car cannot read english, and is for some reason unaware of the issue.
Vandalism is not a rational course of action in this situation. | 175 | 146 |
Does the number of wounds on a human affect how quickly each individual wound heals? Why or why not? | I cut my hand recently and though about this. Is the work all local to the wound site, or is there some other component supplied by my body at large?
Say there are two scenarios, scenario 1 is that a person falls and scrapes their hand. Scenario 2 is that the person falls and scrapes their hand in the same way, but also get numerous (but separate) cuts and bruises. Does the hand wound heal at the same rate in scenario 1 and 2?
Thanks. This has been bugging me all day. | Hey, i am a future wound specialist(it isnt a specialization yet, but it soon will be and i have taken part in the founding charter to get it as a specialization(my real specialization is just primary, but i spend a lot of time doing woundcare)
theoretically, they should heal at the same time as long as they are both equally exposed to whatever microbes are around, equally exposed to the sane conditions. Now, the big part of this is that, as you get older, your body may start to change, perhaps you end up with vascular problems in your legs, so your back wound will heal quickly, but a leg wound will end up being a chronic wound due to vascular insufficiency. So, they would not heal at the same rate. If you have nerve damage, like diabetics with neuropathy, you cant feel the pressure points of your body, so you dont naturally shift around like normal people do to avoid pressure ulcers, so this could cause prolonged damage as the wound is trying to heal, thus slowing it way down, well, really, making it nearly impossible to heal. again, this is because of a vascular insufficiency caused by the pressure. If this doesnt adequately answer your question, just let me know.
Bottom line, in a perfect environment and specimen, they would heal at the same rate. edit: but i have to say, realistically, no, no wounds heal the same on your body, there are just too many variables. Your vascular system isnt perfectly symmetrical, the environment of locations is different(too moist or too dry will make a wound take longer to heal), and microbes can stunt the healing. In a practical answer, no, they wont heak the same, but theoretically they could if the conditions were uniform. Sorry, at first i thought we were talking theoretically, but upon reading the question again, i think you were asking for a practical answer, so i just editted to include both.
Now, some parts of the body heal at faster rates, inside of your mouth etc, but i figure that wasnt what you were asking about.
Your body doesnt really prioritize wounds effectively, it is all about the right conditions. Just because a wound is around doesnt mean that the body naturally diverts enough blood flow to the wound, we have to synthetically do that with something called negative pressure treatment.
Edit: Also, i should specify that all of this is from the context of an integumentary wound. | 33 | 99 |
ELI5: What happens when a country (like Egypt today) 'floats' it's currency? | Allowing a currency to "float" is to allow the exchange rate of the currency to change depending on the currency exchange market. People can buy and sell at different prices so the demand for the currency will determine the rate at which it is exchanged.
This is in contrast to a "fixed" currency which has a value tied to that of another currency or even something like gold. | 14 | 28 |
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ELI5: Why is Japan's Declining Population viewed as a concern when geographically they are a small nation, and overpopulation is something that seems a like a global issue? | Draw a triangle and split it in half across. At the top, draw "the elderly" and at the bottom draw "the young". This is the ideal society wherein the young people help to support the needs of the elderly. Since there are more young people than elderly, not much burden is placed on young people to support and care for their elderly parents/relatives.
Draw another triangle, but upside down. This time, put young people at the tipped end and elderly at the top. You see that this triangle is unstable. There are too little young people to care for the needs of the elderly population. This is the current issue that a declining birth rate countries are facing.
But that's for a personal level.
On a state and economical level, there will be less people that will be able to work as time goes on, as many elderly become too sick to work/retire. As a result, there will also naturally be less consumption by the population. Thus, this means a general loss in government revenue since less people are paying taxes. The economy might also stagnate due to a lack of business in the country.
As one commentor has pointed out earlier, it is a sign of a dying country. This is true; we have an excessive burden of young people in caring for the elderly, and a stagnating economy. This is why it's a big problem. | 48 | 27 |
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Does increased exposure of suicides lead to more suicides? | There is evidence that suicides tend to occur in "clusters"-- both via the media (mass clusters) and in local incidents (point clusters). However, the evidence for these clusters are mixed, sometimes showing that exposure to suicide increases rates of suicide and sometimes not. Additionally, the reason that these clusters occur is not well understood, as suicide cannot be experimentally manipulated and is inherently difficult to study. There are several theories as to why these clusters occur.
Social contagion is one theory, wherein the exposure to suicide transfers the urge to carry out suicide similar to the transference of a disease. However, "suicide contagion" is a vague term that does not identify specific mechanisms by which exposure influences suicide-- it merely describes the observation that exposure increases rates. Some scientists have described suicide contagion as an imitation of suicidal behaviors, though this is not a very powerful theory, as it does not help to determine who is susceptible to the social contagion effect.
Another possibility is that publicized suicides may increase the awareness of an effective method for suicide. Indeed, studies have shown that, following publicized suicides using a specific method, the rate of suicides committed with that method increases. Exposure to suicide may also increase the risk for suicide by decreasing inhibitions on suicidal behavior, or increasing the idea that suicide can solve problems.
On the other hand, there is some evidence that exposure to suicide can be protective against suicide. Suicidality is known to run in families, and yet point clusters of suicide within families are extremely rare. This seems counterintuitive, since the suicide of a family member is extremely traumatic and distressing (which is a risk factor for suicide), and the theory of contagion suggests that it would increase suicidality. However, the suicide of a family member likely brings the family together to grieve, and social support is a very strong protective factor against suicide. In addition, some research examining media reports on suicide and rates of suicide has shown that exposure to these reports is protective against suicide for individuals ages 25-44.
To really understand this phenomenon, it is important to understand the factors that contribute to suicidality in general. The leading theory on risk for suicide is the Interpersonal Theory of Suicide. This describes that suicide risk is influenced mainly by three factors: Thwarted belongingness (feeling lonely, isolated, rejected), Perceived Burdensomeness (feeling like you are a burden to others, that it would be better if you were not around), and Acquired Capability (development of the ability to overcome the innate, intense fear of pain and death).
Suicide is NOT easy to commit and, despite common belief, is almost never an act of impulse. Most who successfully complete suicide have been suffering for a considerable amount of time (likely from a psychiatric disorder) and who have been contemplating suicide for a long time. So, suicide contagion may increase the likelihood of suicide for individuals who are already at risk, but it is extremely unlikely that it would cause suicide in someone who is not already at relatively high risk.
Sources:
Joiner, J. E. (1999). The Clustering and Contagion of Suicide. Current Directions In Psychological Science (Wiley-Blackwell), 8(3), 89.
Joiner, T.E. (2005). Why people die by suicide. Cambridge, MA: Harvard University Press.
Romer, D., Jamieson, P. E., & Jamieson, K. H. (2006). Are news reports of suicide contagious? A stringent test in six US cities. Journal of Communication, 56(2), 253-270. | 20 | 51 |
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What is a simple way to understand Jean Baudrillard's concept of hyperreality? | I always found the first two paragraphs of *Simulacra and Simulation* to be among the most straightforward, and sorta beautiful.
>“If once we were able to view the Borges fable in which the cartographers of the Empire draw up a map so detailed that it ends up covering the territory exactly (the decline of the Empire witnesses the fraying of this map, little by little, and its fall into ruins, though some shreds are still discernible in the deserts - the metaphysical beauty of this ruined abstraction testifying to a pride equal to the Empire and rotting like a carcass, returning to the substance of the soil, a bit as the double ends by being confused with the real through aging) - as the most beautiful allegory of simulation, this fable has now come full circle for us, and possesses nothing but the discrete charm of second-order simulacra.\*1
>
>Today abstraction is no longer that of the map, the double, the mirror, or the concept. Simulation is no longer that of a territory, a referential being, or a substance. It is the generation by models of a real without origin or reality: a hyperreal. The territory no longer precedes the map, nor does it survive it. It is nevertheless the map that precedes the territory - precession of simulacra - that engenders the territory, and if one must return to the fable, today it is the territory whose shreds slowly rot across the extent of the map. It is the real, and not the map, whose vestiges persist here and there in the deserts that are no longer those of the Empire, but ours. The desert of the real itself.” | 48 | 88 |
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What 'connections' is the brain actually building when you learn something? | Everything I've learned about neuroscience so far has made this statement not really make sense. What about the synapse is actually changing? | Here are some properties which can change at the synapse:
1) The sensitivity of the post-synaptic membrane, making it require more or less input to respond with an action potential at the axon.
2) The amount and type of receptors present in the post-synaptic membrane.
4) Production of neurotransmitters in the pre-synaptic terminal.
3) The branching of axons in the pre-synaptic membrane e.g. after nerve damage you can get axonal sprouting of one axon into a now vacant section of dendrites.
The precise physical basis of memory is still largely unknown. | 13 | 32 |
Which programming language do automated factories use? | I know they're not common right now, but it seems they will be in the coming decades. I think I should try and learn the language(s) that are used in them, so that i'm ready for the changes they bring. | 1) automated factories are quite common....almost every manufacturing process involves some amount of automation
2) the languages are specific to the manufacturer of a particular tool....many of them involve commands such as
> move tool to (3,7,1)
> spin drill
> wait 2 seconds
> stop drill
in short, there is no one language that is used, and most of them are proprietary, and not worth wasting your time learning until you are on a job that requires it. | 54 | 74 |
"How will you help the university reach its goal of 50% female faculty in six years?" | I'm interviewing for a job in a couple weeks and I this will be one of their questions. In order to reach their goal, they would basically have to hire only women during this window, which means I stand no chance if that's their decisive criterion, but I'm curious how men and other non-female identifying people would answer a question like this.
I usually do just fine responding to diversity questions because I can speak about my experience as an immigrant and other relevant areas. In the last offer I received, they said my diversity statement was the best they've ever read, but I'm really at a loss about how to tackle such a targeted kind of diversity. | I would think one thing you could talk about is how you support the goal of hiring more female faculty and how you would take action in that direction if you were in a faculty role. You could also come prepared with stats about the ratio of women to men in your field and why there is a need to support women.
There is also the problem of retention of female faculty for various reasons, mostly related to unpaid and unrecognized labor and the challenges balancing work and family. So you could talk about how you would help cultivate a workplace climate that is supportive of women in terms of retention and promotion, not just hiring. | 318 | 194 |
[The Martian]if future missions find evidence of microbial life on Mars, will there be any way to know its actually native & not just contamination from the hab? | Its understandable in his situation, but Mark made absolutely no attempt to avoid cross contamination. I mean he literally just piled his food outside to refrigerate it. | An easy way to determine if it's contaminated is to compare it to known earth samples and its proximity to the habitat. Everything on earth shares similar genetic markers even plants and humans only have a small percentage difference. Mars should be distinctly different. And samples found hundreds of miles away from the hab site will likely not be contaminated as it's unlikely for earth based materials to survive that far blown by the winds of mars or it's thin atmosphere.
Still microbial life living and possibly thriving after being transplated on mars without special care would be a huge discovery on it's own and possibly inform future terraforming endeavors. | 42 | 39 |
ELI5 Why America never switched to the metric system (or SI), whereas most other countries did. | As an American engineering student, wtf? | In Europe in the 18th century, every little state had their own little measurement systems. What would become the metric system was under development since the 1500s. Some European states saw the logic in adopting a continent-wide standard of measurements, but others didn't. Thomas Jefferson argued in favor of a base-10 system of measurement, but Congress didn't adopt it.
France formally adopted a system very similar to the metric system in 1799. Napoleon then proceeded to conquer most of Europe, bequeathing the French system to those territories. Post-war, most states maintained the system.
In the mid 1800s, Britain saw the need for a standardized system and organized an international conference to firmly establish and already-mostly-established metric system. Most of Europe signed the resulting treaty, and then gave the standard to all of their colonies (pretty much the whole world, minus the US). Congress even authorized the use of the metric system in 1866. But for whatever reason, "customary" units kept their dominance outside of professional applications. This is somewhat true in the UK as well. | 15 | 24 |
Do plants die of old age? | Given enough nutrients, water, space to grow and a source of light for photosynthesis, and ignoring any potential diseases or natural disasters, could any plant - not specifically plants that are known to have survived for long periods of time like Weltwitschias or that aspen tree(s) - live forever? | Many plants are programmed to begin senescence after reaching maturity and setting seed- without a lot of artificial intervention they will not live past their programmed lifespan. This can be as little as a few weeks with some early spring annuals to many decades, in the case of some species of bamboo, where even all divisions of a plant flower and die at the same time wherever they are in the world. On the other hand many perennial plants don't seem to have anything inherent to their development stopping them from living indefinitely | 98 | 273 |
[Waterworld] Why is dirt so valuable? | So I'm watching the movie right now and the mc went into a "city" with a jar of dirt, and basically the clerk said something like "we will buy it from you at fresh water value" and the MC gets enough money to buy the city's whole store and some of their furniture, but why? I understand land would be valuable af in a planet made almost completely of water but why spend so much in a jar of dirt? What are they expecting to get with a jar of dirt? | Fertilize it to grow food. Which is rare. Use it to filter water or other fluids. With salt water everywhere drinking water is at a premium. It’s probably the most heavy material around so might also be used as ballast | 602 | 517 |
ELI5: How is it that Vladimir Putin was nominated for the 2014 nobel peace prize? | Formal nominations may be submitted by anyone in the following categories:
* Members of national assemblies and governments of states.
* Members of international courts.
* University rectors; professors of social sciences, history, philosophy, law and theology; directors of peace research institutes and foreign policy institutes.
* Persons who have been awarded the Nobel Peace Prize.
* Board members of organizations that have been awarded the Nobel Peace Prize.
* Active and former members of the Norwegian Nobel Committee; (proposals by members of the Committee to be submitted no later than at the first meeting of the Committee after February 1).
* Former advisers to the Norwegian Nobel Committee.
If just one of those people thinks you should be nominated enough to go through with it, you can be a nominee. That doesn't mean you have any support or approval from the Committee; 278 people were nominated this year and you can bet there were some they discarded early. | 67 | 137 |
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Are there any real and tangible examples of the Butterfly Effect? | For those that haven't heard of it, here's the definition from Wikipedia.
In chaos theory, the butterfly effect is the sensitive dependency on initial conditions in which a small change at one place in a deterministic nonlinear system can result in large differences in a later state. The name of the effect, coined by Edward Lorenz, is derived from the theoretical example of a hurricane's formation being contingent on whether or not a distant butterfly had flapped its wings several weeks earlier. | A pendulum consisting of two rods (so basically a pendulum with a pendulum attached to it) is an easy example. Small differences in the initial state will make the system behave completely differently. It is still a predictable system though, but in order to make any senseful predictions one would need very accurate data on the starting conditions. A small difference would completely change the movement. | 18 | 23 |
Why does the middle east have so much oil? | I'm sorry if this sounds like a stupid question, because obviously the region is somewhat poorly defined, and there are surely unknown oil deposits in other regions both above and below the sea, but I hope I can still ask this question.
Is there a reason why that region in particular has that much oil? Is there a geological reason for why that much organic matter was deposited around that area and not in, say, central Africa? | The Middle East has experienced the right coincidence of factors over time to create and trap oil.
Oil is formed by heating and pressurizing the remains of microorganisms such as algae. There's a specific window (called, not surprisingly, the "oil window") of temperature and time during which the chemical transformation can occur; if the temperature is too low, the transition won't occur, and if the temperature is too high, the oil converts to natural gas. Once oil is formed, it must remain in the bedrock so that we can access it; just like groundwater, oil flows due to gravity and pressure and can easily escape. It can rise to the surface and disperse, and it can be trapped under cap rocks too deep to drill through.
So, there's a necessary sequence of events:
1) The remains of microorganisms collect in huge quantities, generally at the floor of a lake or sea.
2) The organic material is heated to just the right temperature for the right amount of time.
3) The resulting oil is trapped in place, and at a shallow enough depth that a well can reach it.
The bedrock of the Middle East, by the right series of coincidences, has undergone these steps. It used to be covered by shallow seas where organic materials built up. Much of the bedrock there is sedimentary rock, including non-porous cap rocks, that has undergone minimal metamorphism. Each of these conditions by themselves are fairly common, but the combination of all of them is rare. | 32 | 21 |
ELI5: what do they mean when they say that spider webs are stronger than steel? How is that possible? | As in the title. | It’s based on tensile strength when compared to effective diameter. Spider silk is only microns in diameter, so if you could extrude a steel specimen at the diameter of a strand of spider silk, the spider silk would take more force to break | 42 | 24 |
If liquid helium is the coldest substance we have commercially available to us today, how did we first cool helium down to that temperature without the use of something colder? | Use a refrigeration cycle. Compress it and raise it's pressure (and thus temperature), cool it (reject heat) while at a relatively constant pressure, then expand the gas back to ambient pressure, thereby cooling it further.
Repeat this process using different coolants. Eventually: compress it a lot, cool with liquid nitrogen, expand it back out to some ambient pressure and it will condense into liquid helium. | 122 | 103 |
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After light slows traveling through a medium, does it accelerate back to c upon reentering a vacuum or does it remain the same velocity as it was the moment it exited the medium? | The idea of "the speed of light in a medium" is really just a helpful trick for simplifying a more complex phenomenon.
What's really going on is that the incident wave, as it propagates through a material, causes charges in the material to oscillate and in turn radiate EM 'wavelets'. The combined effect of these 'wavelets' is a wave with the same frequency as the incident wave, but out of phase with it. It's important to understand that these waves still propagate at c, however the light we observe is the sum of these waves. In transparent materials, the resulting wave has the same frequency, but a shorter wavelength, resulting in a wave transmitting slower than the oscillations in the field propagate.
In a vacuum, there are no such interfering 'wavelets', and therefore no apparent slowing. | 21 | 16 |
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ELI5: Why is the British Pound worth much more than the USD, when it seems like the equivalent goods cost the same face value amount? | Point of sale costs, government services and methods of taxation all matter.
When you buy X in the UK you're buying all of the labour along the chain. So if the guy who delivers the package to the store, the store clerk etc. all get paid more in the UK you're paying more money for the same product otherwise.
It's not easy to compare "The US" to "The UK" either. Costs in New York or London are relevant to averages, but you shouldn't compare the cost in London versus say Texas.
Then you get into other 'costs'. If you need healthcare in the UK the government has your back. For that about 10% of GDP covers everyone in the country and provides better care. In the US if you need healthcare the government might have your back (~7% of GDP) but might not, at which point you pay out of pocket or have private insurance (~10% of GDP). And lots of stuff like that. This means the average british person is paying more in taxes towards healthcare, but less money overall for healthcare (and getting better care) compared to the average american.
Then you have just straight up cultural differences. Comparing the price of a can of coke between the two places isn't necessarily indicative of 'typical beverage' because the british and americans consume different things. This applies to cars and houses and expensive stuff too.
So what you do is you start doing complex averaging. So you add up all the stuff people spend money on, housing, transport, food, healthcare, education (including post secondary), entertainment, power, telecoms etc. and you say what does 30 000 pounds in income get you in the UK versus 51KUSD in the US? And currencies float up and down because these are constantly being reassessed and constantly have many factors playing a part, and in the end it's just an average anyway. Because 51K in New York city is not the same as 51K in Plano Texas, and 30K GBP in London is not the same as 30K GBP in Northern Ireland.
Oh and how you do taxes is tricky. The EU is big on value added tax (which is about 22% on average or something), and looks a lot like a sales tax, whereas the US has more income tax. Some countries are borrowing more than others to provide services etc.
**TL:DR** there's no simple 1:1 comparison. It's about the average of all of the spending that happens, which requires considering a LOT of data about a lot of different things.
| 35 | 100 |
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CMV: Children should not have a life priority over those who are not children | I don’t see any reason for why children are always prioritized in terms of healthcare, resources, and/or other ways.
I get that children are cute and pure, but they do not benefit society the way a person who work does. I acknowledge the fact that they may grow to become someone employed but there is no way you can know that for sure.
You might counter my opinion by saying that they have lower pain tolerance but that isn’t really fully accurate to me, since I think age doesn’t define pain tolerance. | Children are still developing. There are issues that can arise which can lead to irreversible effects. Children are prone to ear infections. Untreated ear infections can lead to hearing loss. Giving children access to healthcare can reduce the number of deaf and hearing impaired adults meaning fewer services needed to support them, more adults who can perform jobs that require full hearing. Can an adult lose their hearing from an untreated infection? Sure. How common is it compared to kids (a lot less)
Nutrition in early life can affect future development. An adult can be malnourished for a few months but bounce back. A child who is malnourished May never fully develop properly or even develop fully mentally and may have a lower IQ. Providing free school lunches/breakfasts not only helps make sure kids get at least one or two full meals a day, it helps them focus and learn better.
It’s not about this child vs that adult. It’s about society as a whole benefitting by making sure children reach adulthood healthy and fully developed. | 1,185 | 820 |
ELI5: How did they know splitting the atom, fission, would release so much energy? And why would the opposite be also true, fusion? | Small atoms release energy when they combine, big atoms release energy when they break, and both gravitate towards 'medium' size. That 'medium' size is the iron atom.
Fusing large atoms or splitting small ones does not release energy, but actually absorbs energy.
Scientists studied radioactive decay a while before the manhattan project. They noticed things like induced radioactivity and nuclear fission, and found that these released energy as heat. From there, the idea of nuclear fission chain reactions emerged and countries then started research programs on the idea. | 1,056 | 1,308 |
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Should I put my small online business on my CV for graduate program application? | Hello,
Do you ever apply for a graduate program while you are unemployed or doing your own small online business? If so, how do you put it in your CV for a graduate application?
I plan to apply for a graduate program but I don't have degree related jobs since I've got my MSc. This is due to Covid and the political unrest in my country. The companies stop hiring. All are closed. The industry is not running anymore and thousands of workers are unemployed at the moment. I am no different. All I can do to earn is doing my own small online delivery business from time to time. I don't think I can find a proper related job any sooner.
So can you please give me some advice on how to put this period in my CV? | You can list your small online business as work experience. It would be even better if you could relate some of the soft skills you acquired from this experience that relate to this program in the cover letter, if applicable. | 42 | 41 |
ELI5: Why does the price of everything keep going up? | Central banks, more or less, have control over how much money is in circulation and also have a fairly good idea of the amount of stuff produced and services provided. As such, modest inflation, and thus increasing prices, is a policy choice.
The reason why is that it incentivizes investment (why hold cash instead of spending it or lending it to someone with a productive use for it if it will decline in value over time?) and helps avoid deflation (decreasing prices), which creates a feedback look sapping investment and spending (why spend your money now when it will be worth more later?). | 417 | 437 |
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When my computer calculates something and uses say 1KJ of energy to compute it, is any heat taken to do the calculation? Is it all waste heat? | When a computer computes something does any energy go to finding the answer rather than just waste heat? Is there a theoretical limit for how little power it takes to compute something? | Basically, you're asking if your computer unavoidably needs a certain amount of energy to do a computation, the way that the energy of the desired visible light emitted by a light bulb sets an unavoidable minimum energy requirement, yes?
There are a number of theoretical limits to computation. The one most relevant to your question is Landauer's principle, which states that irreversibly changing one bit of information needs a minimum energy of *k**T*ln(2), where *k* is the Boltzmann constant and *T* is the temperature of the system. However, at room temperature of 300 K, for example (and if your computer were using anywhere near the Landauer limit for its current computations, it would be operating at room termperature), this limit is approximately 2.9*10^-21 J. So, even if your computer needs to change one quadrillion (10^15 ) bits per second to do its calculation, Landauer's principle sets of a minimum power consumption of about 3 microwatts. Thus, this limit is negligible compared to the power consumption of any current technology.
Landauer's principle only applies to irreversibly changing a bit. Thus, there is theoretical interest in reversible computing. While no real physical process can be perfectly thermodynamically reversible, there is no known limit on how closely it can be approached. However, no current technology uses the principle of reversible computing.
There are other theoretical limits to computing. They are all extremely small relative to current technology, so it is fair to say that almost all of the energy your computer uses is not required by currently known theoretical minimum power requirements. However, there could limits that are not yet known. Also, it is definitely not possible to do any computation with literally zero power. | 12 | 26 |
ELI5: How does sleep debt/build up work? | If I were to sleep for 24 hours could I then skip the next 3 days of sleep? If so how does it work and if not why does it not work like that? | The first question to answer is, what is the point of sleep?
Among some other functions, the primary purpose of sleep is for the brain to enter into a maintenance mode. Think of it as that 2am hard drive defragging that runs when you wouldn't otherwise be on your computer. Instead of space reallocation, however, the brain's process is biochemical and serves to "wash and replenish" the brain's cellular machinery, something that can't happen when the individual is in a waking state. This process is both reactive (meaning it doesn't do any good to do it before there's a mess to clean) and rate limited (which means that it takes X amount of time to achieve Y results). As such, the normal waking/sleeping cycle maintains an equilibrium of building up a mess and cleaning it up.
You can't bank sleep. That would be similar to cleaning an already clean house for the sake of cleaning it and expecting any mess that you make in the future to come out of the extra work you did. It just doesn't work like that. | 11,934 | 10,977 |
[Mad Max] How easy would it be to become important joe? | Pretty easy... Be named Joe, and have some knowledge that makes you important to someone in a position of power. Mechanics, engineering and medical know-how would be good.
Now, becomming Imortan Joe is a different issue altogether. | 80 | 47 |
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Do you burn more calories as an exercise goes on? | For example say do I burn more calories on the last squat of the set versus the first squat of the set.
I'm curious because you are struggling more as the exercise goes on so it would take more energy to continue? | What you're noticing is likely not an increase calories being burned, but simply muscular fatigue.
Your muscles use a molecule called atp to provide the energy to contact fibers. Atp is synthesized in part from creatine phosphate, another molecule stored in your muscles. When you use your muscle enough to deplete your creatine store, your body switches to glucose to provide energy, which is stored in your muscles as glycogen. As your exercise goes on, the amount of glycogen and creatine in your muscles goes down, making it harder to produce the same force since you have less energy sources in your muscles.
In addition, the byproducts of the chemical reactions that allow your muscle fibers to contact can interfere with ion levels in your muscles. Various Ion levels are very important to allow your muscles to react properly to signals to contact from your nerves, and high levels of these byproducts can reduce your your sensitivity to nervous signals, making you weaker. | 25 | 64 |
[Dinotopia] How large is the island of Dinotopia? | 240 miles (385 kilometers) in length, and approx. 260 miles (420 kilometers) in breadth. In the center of the "main island" was the Rainy Basin, which with the Great Desert made up most of the island. It would fit pretty neatly inside of California | 13 | 24 |
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ELI5 Why don't we call countries by the names they call themselves? | For example, Germany is Deutschland. Why do we not refer to it as such? | This is an awesome question...I have ALWAYS been curious about this (specifically in the example you have provided).
Looking at it again, for the first time, it appears to be a situation where the name "Germany" developed for that region LONG before Deutschland became a unified country and they started referring to themselves thusly. The Romans were calling the land area "Germania" when they first visited because that was the tribe that they encountered...the Spaniards were calling it "Alemania" because of the tribe closest to their border.
Looking at the United States, we are called many things that don't really sound like United States:
* Vereinigte Staaten von Amerika (German)
* Sahalat (Laos)
* Estados Unidos de América
With Japan, it is a bastardization of the original name Cipangu...it went through several iterations as it traveled around the world by ship that eventually resulted in "Japan" in English.
(Thanks to MentalFloss.com for the additional information). | 929 | 2,134 |
CMV: r/AITA Does More Harm than Good | r/AITA is full of pretty obviously fake stories, which are the ones that tend to get upvoted. Often the fakes are clear strawmen about feminists/trans people/gay people/black people/any activist or minority group, which gets eaten up by people who love a chance to go "women bad"/"this is why trans people look stupid"/"this is why I hate liberals".
I've been on the subreddit for a short while because I like it in theory and I think there are a good deal of real stories that need some perspective, but I've gotten sick of seeing stories that I would bet real money are fake that just give people the opportunity to shout about how much they hate feminists or whatnot. If the subreddit was better managed, then I think there would be value, but when it's just full of popular fake stories by people making up things about The Eeeeevil Liberals/Gays/Women/etc I have a hard time seeing any value.
I'd like to feel less cynical about the subreddit and maybe hear from people that have been positively impacted, which is why I posted here.
INB4: "You just don't want to hear criticism of your side" and the like, it's not that I don't think bad feminists/asshole trans people/etc exist, it's that I'm sick of seeing *obviously fake* stories repeatedly showing up, often with the same plot. (EX: "my friend had a woman-only wedding and wants me, a man, to pay for it and I said no, AITA? she thinks I'm a pig" or "some trans person told me to change MY name because it's their deadname, I said no and they beat me up, AITA?" - I've seen loads of these variations). | First off, i don’t think it’s just as easy as “moderate better”, because it really isn’t clear which stories are true or fake in most cases
Second, i do find value in it if you come at it with the perspective like the trolley problem—assume that all stories are fake, and use them as thought experiments to reconcile how your stated first principle beliefs match up with specific edge cases
Example: you hold freedom of businesses in high regard, to the point that you think they should have the right to serve/refuse whomever they want. Someone posts “i refused service to a man because he was black AITA?” This hypothetical could make you uncomfortable and reevaluate your first principle belief in absolute freedom of businesses. | 12 | 21 |
Eli5:why is it that when a clear item(like clear wrappers)is crumpled it turns white? | A clear substance becomes white when tiny cracks, localized crystalline structures or other impurities are introduced due to strain.
The white look is due to the same dynamics that make clouds and seafoam look white. That is, the scattering features involved are the same or bigger than the wavelengths of light and so reflect them all similarly. When you get smaller particles you see color-selective scattering, and you get sunsets and blue skies! | 60 | 121 |
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why are so many popular scientists staunch materialists/physicalist/naturalists? | I've noticed a lot of modern and popular scientists seem to be hardcore materialists and I'm using materialist synonymously with naturalism and physicalism. The modern scientists I'm referring to are those like Sean Carroll, Richard Dawkins, Dan Dennett, Sam Harris etc. | One thing to note is that your sample isn't very representative. You only have four people, and only two of them are actually scientists. All of them are popularizers of atheism. It's no surprise that they are "hardcore" naturalists. They promote naturalism in opposition to the supernaturalism of theism. You can't really learn anything about scientists in general from that sample.
That being said, although scientists may or may not be "hardcore materialists", most scientists are naturalists. Naturalism has proven to be an effective paradigm for scientific research. | 74 | 45 |
Dissertation topic: What I can't tell my professors.... | I'm a first year PhD student struggling to find a dissertation topic. The first topic I chose shows a lot of promise, but is costly/risky to implement, so I'm putting it on the back burner for now. On my advisor's suggestion, I've picked up a new topic that he is also working on. It's interesting and he has data, so I've been pursuing this topic. Now, another prof in my department sat me down and asked if the topic I'm pursuing is something I'm "really passionate about". He is rather discouraging of this topic, and even quickly threw in the fact that he has this great paper idea all ready, but nobody to implement it (it is, incidentally enough, in my research area interest, as well). So, I have two questions: (1) are both prof's just trying to turn my dissertation into something they can put their name on/work on simultaneously with me/use me to pursue one of their ideas? And (2) I'm passionate about LOTS of subjects in my field! I can envision staying up at late at night for a variety of different topics, not just one. Personally, I think this is a good curious-about-learning attitude to have, especially as a new academic. Why not be "bright-eyed and bushy tailed" at the start? I can be jaded later. But, apparently, professor's think you should have a single, narrow focus. I keep having to lie and justify why I'm pursuing one particular avenue. In reality, I could go a variety of directions and be equally happy in my research. And, as that's the case, I'm choosing the subject that is most topical and has the best results/career potential. How do you know when you've found "the right" dissertation topic?? | It's important to remember two things:
1. Your dissertation isn't the end of your publication history—it's the beginning. Picking something to do here doesn't close down any of those other avenues. Write down the other ideas and put them away; you'll be very glad to have them once the first thing is done!
2. The best dissertation is a done dissertation. A Ph.D. program is an apprenticeship; your goal should be to learn what you need and get the hell out so you can get a real job that actually pays a living wage. | 48 | 16 |
ELI5: Why vitamins have expiration dates. Do vitamins and minerals degrade? | Many chemicals oxidize and lose their intended properties, just like food (which incidentally is made of chemicals :P). This means that free radicals (oxygen ions) attach to different parts of the vitamins/rip off a few atoms.
So the vitamins could either become inert and useless, or potentially poisonous.
---
More ELI5:
Our air will over time cause the vitamins to change their chemical structure. This makes vitamin A no longer vitamin A - but some deviant variation. | 14 | 38 |
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Why don't we have on Earth those funny craters present on almost every planet? | I mean, I just saw the brand new picture of Mercury from orbit, and they're all over the surface, just like every planet and moon in the Solar System. Or am I wrong? | Two factors:
1. Earth's surface is geologically active, so older craters will eventually be buried or torn apart by tectonics.
2. Earth has enough atmosphere, so there is more erosion to wipe out craters.
And actually, not every planet or moon is heavily cratered, you don't see many craters on Venus, Io, Titan or Europa; and you don't see them at all on Jupiter, Saturn, Neptune or Uranus. | 30 | 19 |
ELI5: Why will water start to taste bad when you leave it in a glass for too long, but will taste fine when you dispense it out of a tap where it's been sitting for months? | If you leave water in a ceramic, glass, or cup it will start to taste bad after a day or two, even if it's covered with a lid. However, when we pour water out of a tap into a glass it will taste fine, even though it's been sitting for days/months in a water reserve tank. Why is this the case? | Normally, water has a bunch of dissolved gases in it, as well as dissolved minerals that can react with oxygen. Inside the pipe/tank, those gases have nowhere to go and there's no oxygen to react with, so the water doesn't really "age". As soon as you sit it out in the open the dissolved gas mix changes and any reactions that need oxygen to proceed can get going. There's enough of that going on in most water to change the taste enough to notice. | 1,888 | 2,413 |
ElI5 Why do city governments care when people have garage sales? | Had garage sale over the weekend and public security showed up and gave us a written warning saying we needed to have a permit to conduct a garage sale and we had 24 hours to get one. My question, why do they give a fuck if i'm selling my old junk on my property? | I expect that requiring you to have a permit helps them track how often you're having a garage sale
Many cities have limits on how often you may have a garage sale because they do not want you having garage sales on a regular basis.
You're living in a residential area, not a commercial area. They don't want you having a garage sale on a regular basis because that would be very much like you were running a business.
Your garage sale brings more traffic to your neighborhood. The extra traffic can be disruptive to the neighborhood. If you had frequent garage sales then you'd be responsible for bringing a lot of traffic to your neighborhood and causing a lot of disruption. Your neighbors would not appreciate this.
This is why cities regulate garage sales. | 20 | 19 |
[SHAZAM] Does the marvel family have equal powers?Does their power divide the more of them transform? | Does Billy and his foster siblings get equal speed strengh, powers etc. When they transform? Or are they weaker than Billy? | It has varied from universe to universe.
The Post-Crisis Universe had the power being literally shared between Captain Marvel, Captain Mary Marvel and Captain Marvel Jr, and if all three were transformed, they weren't as powerful as they would be if only one was transformed.
That has not proven to be the case in other universes. | 18 | 17 |
ELI5: Why can't teeth heal themselves? | Tissues that can heal themselves need to be made of living cell that can divide and grow more cells from a small amount of living cells. Much of teeth is mineral that was deposited by living cells but after that initial process, teeth are mostly non-living very hard mineral or hard mostly non-cellular tissue. The cells that initially made all that mineralized hard stuff died and are no longer around to do it again. | 236 | 726 |
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How to refer my previous work without breaking double blind review process? | I'm about to submit a paper to a CS conference that has a double blind review process, and that rejects papers that expose the authors' identity in the text.
However, the work is an extension of a previous work we published last year in the same conference. We will be referring to that work a lot, write a similar problem formulation, show new results on the previous datasets, and in general it is clear that the current work extends the previous one and should be read with that in mind.
how should I refer to the previous work throughout the paper? I find it hard to believe the reviewers won't guess that the work is from the same lab, and don't want to be rejected solely because of that. | It is a bit difficult to manage, but you have to write the paper as if that previous work was someone else's. While that seems like an unnecessarily burden, this paper must stand on its own regardless of whose work it builds upon, so it's a good practice to think that way even when the process is not blind. | 19 | 17 |
ELI5: What exactly is a Tensor? | For ELI5, it's better to give an example of a tensor than the actual definition. Suppose you have a cube made of clay. How many different ways are there to stretch it?
Well, you could pull out on the top and bottom, stretching it vertically. Or you could pull on the left and right sides, or the top and bottom sides. So that's three different directions of stretching.
But you could also push the top side to the left while pushing the bottom side to the right, shearing it out like spreading a deck of cards. Or you could push the top forward and the bottom backward. Or the left side up and the right side down. Or ...
Anyway, you can push/pull in three different directions, for each of three different pairs of faces, for a total of nine unique possibilities. You could also have a combination of more than one of these at a time.
This example is known in materials science as a "strain tensor".
You could express this as a "direction that also has a direction", which is what /u/Depressed_Maniac is saying. You could also make a 3-by-3 table with an amount for each of the 3 sides and 3 directions, which is what /u/Kayuwaii is saying.
There are lots of different cases in which this comes up, and some of them have more than 3 different directions (rows/columns in the table), and some of them involve directions that have directions that have directions (!), so you'd need something more complicated than a 2-d table to describe them. But they're all tensors. | 18 | 40 |
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How does the “I want to teach but not be a research professor” after PhD route go | Ignorant and naive phd student here. My plan a has always to work towards being a professor but the thought crosses my mind that I may just want to be a full time educator. What are the options like? I assume instructor positions at state schools are slim pickings?
In physical sciences for reference | There are more teaching-heavy faculty positions than research-heavy ones. Most colleges are not research institutions. You apply the same way you would for research positions, but they'll want to know more about your teaching philosophy and possibly see a teaching demo. Getting experience teaching more than one class and attending some teaching training can help you be more competitive. | 153 | 128 |
eli5 what are Computer “Drivers” | After painstakingly installing printer drivers for a thermal printer at work I realized I still don’t truly understand what I was installing. (Bonus points if you can cover video card drivers too cause idk what drivers are In that sense either) | Drivers are the middle man between the Hardware and the Operating system. their job is to translate the OS's instructions into something the Hardware can interpret and then translate the output into something the OS can show you.
OS> Driver > Hardware
think of them like the " user manuals" the Operating system needs ot be able ot use the hardware, or if you want ot extend an analogy to us humans: picture it as you needing a manual for your brain to be able to command your limbs and understand the stimulus it receives from them.
without drivers, software would need ot directly program the hardware and considering how many different models of any single device exist out there this is impossible(or at least would be impactrical in terms of programming time) | 3,273 | 2,555 |
ELI5: Is logic subjective? (after a long time I still don't understand this, please help) | Logic is the process of how things make sense for us. Everyone uses logic the same way.. In that sense, Logic is objective.
In a debate there's often a perfectly logical argument dismissing another perfectly logical argument.
So which argument is actually the "logical" one? Or are both arguments equally as logical?
You can always poke holes at an argument no matter how "logical" it is.
Even if one person "wins" the argument, that only means the other person cannot come up with any more ideas to argue anymore. It doesn't mean the winner is "more logical one"
So in this case, would that make logic "subjective"?
**EDIT: thank you everyone here for helping me. I think I understand it a lot more now. But I'm always welcoming more answers**
Thanks
| Logic isn't subjective. Broadly speaking, logic is the study of how to correctly infer conclusions from prior knowledge or assumptions. What's special about a logical argument is that if it's assumptions were right it's conclusions are always right. A logical argument can still be wrong because it's assumptions were wrong. If a logical arguments assumptions are false it's conclusions can be either right or wrong. That's where the subjectivity lies, different people may disagree about the assumptions and not be strictly wrong, thereby may disagree with the conclusion .
| 27 | 39 |
Why do sunburns seem to "radiate" heat? | It's simply a matter of 1) increased bloodflow to the area and 2) various biochemical processes involved in the healing. When your body senses the damage from sunburn, it activates the immune response, which triggers increased blood in order to deliver white blood cells needed to fight potential infection and building blocks to repair the damage. This rush of blood by itself will increase the temperature. In addition the host of chemical reactions associated with the heavy cellular construction work needed to clear debris and repair the tissue will generate additional heat.
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ELI5: Why don't all MLB baseball fields have the same dimensions? | There are many dimensions that are the same, such as distance between bases, distance from the pitcher's mound to home plate, height and slope of the pitcher's mound, the minimum distance to the outfield fence, etc. These standardized dimensions are the most important to the actual play of the game.
The areas where fields are different can be broken into two categories: foul territory and the outfield fence. Both came about in the early days of baseball due to the fact that stadiums had to be located in less-than-perfect locations, and flexibility in fence locations could help equalize fields on different shaped/sized lots (the "Green Monster" outfield wall at Fenway Padk, for example is very tall to make up for the fact that it is rather close-in to home plate, which is due to the fact that the stadium was constrained by a street on that side when it was built). Foul territory was influenced the same way. Odd-shaped lots caused there to be areas where the stands were very close to the a tion, but the strict 90 degree geometry of the baseball diamond sometimes created gaps between where the stands were and where a grandstand that foloowed the property's contours might be.
As baseball became an ever-larger business, these designs became more about local history or creating advantages for the home team (an unusual corner in an outfield fence can cause a ball to careen in a direction a home-team player could anticipate, but that might surprise a visiting outfielder) but there is no outcry for dimensions to become more standardized--in fact, these idiosyncrasies are seen as adding to the charm of the individual parks--so stadiums continue to add their own character through unique outfield and foul-territory dimensions.
These playing differences can be attributed to two simple quirks of baseball. First, the area out of bounds (foul territory, or the area not between the first and third base lines) is still a usable part of a baseball field. And secondly, since offense and defense are played in turns, but by the same set of players llaying both sides, a team can be built according to strengths that take fhe park shape into consideration.
For reason 1: a ball hit into the air and caught in this foul territory counts as an out, so it's construction makes a difference in how a team is positioned and how batters approach their at-bats. On fields with a lage amount of foul territory, more pop-ups will be caught for outs. A pitcher might be more willing to trade a small chance at a long hit in order to try to cause the batter to hit a pop-up into foul territory for an easy out, while the batter will not swing at as many close pitches to avoid fouling a ball into the air in-bounds that may be caught for an out.
On fields with small foul territories, a pitcher won't be able to rely on a as many pop-outs, and may pitch a batter in a way to cause more ground balls to be hit. Batters, on the other hand, will be able to swing more freely because it will be easier to deflect a close pitch into the stands rather than into the air above the in-bounds foul territory of the playing field.
For reason 2, a team with a large outfield can afford to spend less on pitcher's because lesser-quality pitching will be masked somewhat by a more difficult distance to hit a home run. This team would spend more of its budget on fast outfielders who could not only cover the larger area and reduce doubles and triples afforded by the larger dimensions, but who could run faster when batting to stretch singles into doubles or doubles into triples in the larger outfirld, against players no accustomed to covering such an expansive area. | 17 | 24 |
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Do waves with lower frequency travel further than waves with higher frequency? | What does frequency have to do with attenuation over distance? Does it depend on the amplitude or energy of the wave? Googling about this quickly got me more confused. What is the difference between Energy, Power and Intensity of a wave? How do these relate to the frequency and amplitude and more so the attenuation of a wave over distance?
EDIT: I was thinking about electromagnetic and sound waves when I posted this question. But I would not mind learning about ocean waves as well :) | Subject question:
Low frequency do travel further than high frequency on earth because the high frequency wave lengths are more easily absorbed by the molecules in the air.
First Comment question:
Attenuation is the gradual loss of energy which will in most cases happen over distance. This has to do with what absorbs the particles riding on the specific frequency, as well as what has a multiplication effect (see resonance).
Next question:
More amplitude, more energy, means more energy to be lost, means it can travel farther before it loses all of it's energy generally speaking.
Third and Forth question:
Energy versus Power versus Intensity versus Amplitude, these terms are probably confusing because in specific in applications the variants of the term mean different things but certain things are understood. For example, sound equipment, most people who talk about Power, are talking Power(RMS) not just Power(Peak to Peak). In addition depending on the industry certain terms are or are not used. In general these are all talking about the same thing though. Amplitude = Energy = Intensity = Power, and so this means the wave will travel farther in general. | 13 | 48 |
I've been out of high school for years now, but I distinctly remember my high school bio teacher telling the class how we're living paradoxes, something to the matter of "It's incredible how destructive oxygen is, yet how dependent aerobic organisms are on it." | I tried rationalizing it as being something akin to rust, that eventually oxygen binds with too many elements in the body, and prevents certain processes from functioning properly. But I never did get a straight answer out of my bio professor. Did she mean that, in general, O is destructive, but it's a force for good in life? Or did she mean that it's destructive, and we battle it's destructive properties to utilize it for its life-giving ones?
I wish there was more context to give; it was just a high school biology class. | Oxygen is very reactive. As such, it can be both destructive and useful.
Your bio teacher seems to have found this remarkable. Looked at another way, though, it's not unusual that many of the most useful things are also the most dangerous.
Consider the opposite case: a totally inert substance that doesn't react with anything is not as useful, but it's also not particularly dangerous, for the same reason. | 29 | 17 |
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