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Eli5: Why aren't baseball fields all the same size? | Why wouldnt there be a regulated size every field has to have | Because the rules allow for stadiums to design fields within certain parameters. That design is in order to benefit the team.
Baseball teams play half their games outside of their own field, so it evens out. Every team gets half their games in their home field which is tuned to their advantage.
The result is that teams win more often at home. Since most people who attend baseball games live nearby, that means fans see their team win more often, which means they have a better time, drink more $10 beers, and come more often. | 77 | 57 |
[Star Wars] How can clones tell each other apart? | They have numbers, they get tattoos and strange haircuts, they paint and mod their armor, they carry specialized weapons, and sometimes you can just know someone well and be able to tell them from people who look like them. | 35 | 17 |
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CMV: According to a utilitarian ethics system, certain forms of slavery are permissible (perhaps a moral requirement), and this makes utilitarianism a dangerous philosophy. | As I understand it, the basis for utilitarian philosophy is that whatever action produces the most happiness in the world is good, and those actions which produce less or take away from global happiness are less moral or evil.
The enslavement of the minority by the majority, with the minority doing all manner of unpleasant jobs, or working to facilitate happiness for the majority, would produce more total happiness.
Because I regard slavery of anyone as fundamentally evil (except for the forced labor of convicted felons) utilitarianism is therefore an unacceptable and horrific moral philosophy. Change my view! | What you are describing is a common critique of utilitarianism (which is fairly common). What you are describing:
> whatever action produces the most happiness in the world is good, and those actions which produce less or take away from global happiness are less moral or evil.
Is close to *act utilitarianism*. However, *rule utilitarianism* is the idea that the an action is right if it conforms to a rule that maximizes utility. So a rule like “no slavery” maximizes utility (because the positive gains of slavery our outweighed by the negative of the slaves for example).
Alternative discussions include, do you maximize average happiness, or total happiness?
But what you may be thinking, (because a rule like ‘no slavery is a bit of a dodge’) is also called the *utility monster* (a monster who derives so much happiness from eating food, much more so than people, than we should give all the food to the monster).
A common patch for this is *Rawl’s maximum or difference principle*: when utility can’t be evenly distributed, it should be distributed starting at the member with the lowest utility and increasing towards the highest. So slaves have a lower utility than free people, so utility should be directed towards them (by freeing them). Once they are no longer the lowest utility member, then other people get utilities.
So yes, that’s an issue you pointed out, but it was patched a while ago. | 44 | 40 |
If you saw a Tsunami coming towards you, say 50ft waves, would it be better to run towards land, or just stay where you are to dive in and swim upwards? | So waves are coming at you, better to run away, or stay deeper out if you are a good swimmer?
| Unlike waves, tsunamis are not just water going up and down, but the actual displacement of water. All the water near the sea shore is going to be the water that will be flooding across trees and rocks in moments.
Basically, you are screwed either way. | 32 | 29 |
How are published review articles regarded as an undergrad, as opposed to primary/lab research? | Hello everyone, I hope this is the right place to ask, and thanks for reading!
Due to covid, I didn't get the chance to do real experimental research for my final year project in STEM-research. Therefore, I wrote a (narrative) review, and I got the opportunity to publish it in an academic journal. However, I didn't learn any real lab skills or experiments during undergrad (except a week-long course during which we did some basic pipetting)
How would you regard this if someone applied to an internship in a lab, or for an internship project? Would such an article still give the indication that someone could do research, even if there are no 'hard' research skills? Or would you prefer candidates who did more experimental stuff?
I'm applying to research internships currently, and I am trying to get an indication of where I stand/what I could apply to. Thank you in advance! | I would say the ability to write, understand the publishing process, and being successful at it is incredibly valuable. Knowing lab work/instrumentation is a plus, but lots of people learn this while in grad school. | 40 | 36 |
ELI5: How exactly does the Atomic Clock work? | What material does it use to power it, if I'm wording this correctly...?
What would happen if it was off by a few seconds? Would a new position effect the time displayed? | An atomic clock can be based on several different designs, but they all work on a basic principle of measuring the frequency of radiation emitted by atoms of some element in a chamber.
Knowing the frequency that the particular element "oscillates" (a very general term but serves for this discussion) at allows it to be used as a very accurate metronome, which then acts as the basis for a clock.
Most atomic clocks use the element cesium, which has a frequency of 9,192,631,770 Hertz. That means it "oscillates" (actually, transitions between energy states, but that's not important to understand how it's used as a clock) a little over nine billion times a second.
Knowing the oscillation frequency and then measuring it in a device creates an incredibly accurate timekeeping mechanism.
As to accuracy of the time displayed, it's important to understand that any clock is really just a device that counts out moments of time- they may be larger and less accurate, such as with a grandfather clock and its pendulum, or smaller and far more accurate, such as a cesium clock.
But the time displayed is simply a function of knowing what time it is and then letting the clock drive the display by counting out those slices of time. If the clock is inaccurate because it does not measure its moments very accurately - such as with a grandfather clock or a wind-up clock that may lose or gain a minute every few days, for example- then it has to be adjusted.
Atomic clocks have a very, very small amount of drift in their measurements, simply because it's impossible to *continuously* monitor time changes with our current technology- we have to do it in slices, like a pendulum, metronome or changes in energy states of an atom.
But atomic clocks are the most accurate timepieces we've ever created, and their drift is so small as to almost not bear mentioning.
| 22 | 38 |
If the earth was placed at the border of our universe (some planet must have ended up there?). Will half of the sky be completely black? | Or what will we see or be able to measure from the other side? | The observable universe — which is often what people mean when they say "the universe," and that ambiguity of terminology causes a lot of confusion — is simply a sphere centered wherever the observer in question happens to be. The radius of the sphere is a function of the age of the universe. Every point that lies within the sphere is sufficiently close to the observer that light has had time to reach the observer from that point in the time that the universe has existed.
So if you could magically teleport yourself (and your telescope, of course) to a point at the very edge of the observable universe as seen from Earth, you would find yourself at the center of a sphere of stars and galaxies that looks entirely similar to what we see all around us. You'd be seeing stars and galaxies that no human has ever seen before, because light hasn't had time to reach us from those stars and galaxies since the beginning of the Big Bang, but other than that, there'd be nothing particularly interesting about your view.
This raises the obvious question: If light cannot yet have reached us from those places, how can we know what you'd find there? Well, the honest answer is we don't. Not for sure. But it follows logically from the assumption that the laws of physics are the same everywhere. The technical term for this is *translational invariance.* Wherever you go, the same basic laws of physics apply.
The reason we have stars and galaxies *here* is because the laws of physics caused them to form out of the soup of matter that emerged from the early stages of the Big Bang. Those same laws of physics apply *there,* so it follows naturally and inevitably that there will also be stars and galaxies wherever you go.
Of course, it's technically possible that the laws of physics are *not* the same everywhere. But in many centuries of people observing the universe on scales both large and small, there's never yet been any evidence at all that the laws of physics aren't translationally invariant. So while it's an assumption, it seems to be a pretty darned safe assumption to make. | 151 | 118 |
In the absence of artificial light, do moths attempt to fly towards to the moon? | Insects, including moths, do not fly directly to a light source, but rather use it as a beacon, and try and maintain a constant angle to it. With the moon at effectively infinity, this gives a straight path, but with a closer light they end up describing a spiral around and then into the light, which then appears to an observer who only sees the end as if they have flown towards it. | 54 | 22 |
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ELI5: What is the real world significance/ benefit of calculus? | I stink at math and would like to understand! | The most unhelpful, but most true answer: Basically everything.
Almost everything runs on, is modeled by, understood using calculus to some extent. Newton's second law, which is the basis of any kind of physical motion, and so used in all forms of engineering, mechanics, fluids, etc, etc, etc, is an equation in Calculus. The equations that allow us to discuss how electricity will flow, what magnetic fields will do, how light will propagate, are Calculus equations. Even many things in something that may seem like it has nothing to do with Calculus benefit from it, or discrete versions of it, particularly in Computer Science.
Your whole world runs on Calculus. If you take advantage of anything invented after 1700, then you're more than likely directly benefiting from Calculus. Calculus is an infection. We are in symbiosis with Calculus.
Calculus tells us how things change, and everything changes, so we need Calculus for everything. | 183 | 104 |
ELI5 how Tilt Shift photography works. How does it make things look like model landscapes? | Every time I see one I don't even fathom how it does that | What you're asking about is actually known as "Tilt-shift false miniaturisation". Tilt-shift lenses allow you to adjust the "tilt" of the lens (ie. the angle between the lens and the film/sensor) and the "shift" (offsetting the position of the lens relative to the film or sensor).
As SneakyPete27 said, this is useful for things like minimizing converging lines when photographing tall buildings, but it can also be used to make false miniatures. It does this by creating a very narrow depth of field (which is the area in which objects are in focus), blurring out the rest of the image. This is very similar to how a macro lens behaves with small objects, and tricks our brains into thinking the photo was taken with a macro lens.
You can then do other things such as bumping up the saturation of the image to make everything slightly less realistic and "plastic model" looking.
You don't even need a tilt-shift lens to create these photos - you can add the lens blur effects to any photo using Photoshop for instance. There are many tutorials on the web of how to do this. | 17 | 80 |
What careers/industries meet at the cross-section of Economics and Law? | Soon to be Law Student with a background in Economics/Finance, what opportunities are there for attorneys who want to work in the realm of economics? Academics/ Academic Writing? Antitrust? Legislature? | Antitrust, Acquisitions, Competition regulatory agencies, consulting, audit, international organizations’ roles that needs understanding of economics and know how international law system works. Lots of opportunities | 65 | 71 |
ELI5:Why is it important to keep finding big prime numbers ? | And, there are practical uses as well.
- There are mathematical techniques that turn prime numbers into locks. The bigger the number, the stronger the lock.
- Some of these locks make keys from reasonably large prime numbers chosen at random.
- Numbers made of solid ones in binary are easy for computers to work with. (11 111 1111 11111 111111 etc.) These are called "Mersenne numbers", which makes Mersenne *primes* especially useful large primes. They're easy to guess, so you can't use them as "random" large primes.
Why not:
You might write some code that can do math with 4096-bit numbers.
The smallest period over time for which modern physics makes sense is the Planck time. If you start at the Big Bang and start counting the age of the universe using "Planck times" as your units, you would be up to 61-digit numbers by now. In binary, that's 203 bits.
You cannot imagine how many 203-bit numbers there are without a powerful metaphor like that. You would need a much more powerful metaphor to get from 203-bit numbers to 4096-bit numbers.
It's easy to pick random 4096-bit numbers, obviously, and math with them is decently fast. Thus the usefulness in cryptography.
Of the 4096-bit numbers, about 1 in 2839 are prime. It's surprising that we can estimate such precise odds, but the Prime Number Theorem makes it possible. Take the number of digits (4096), multiply the natural logarithm of the base (ln 2). The PNT says that this estimate becomes more correct with more digits.
Mersenne numbers are much rarer. So rare, you cannot imagine how rare they are. In the near-infinity of 4096-bit numbers, only 4096 of them are Mersenne numbers. Only some of the Mersenne numbers are prime.
You cannot guess a randomly-selected 4096-bit prime, even with an entire universe of computing power. But it's pretty easy to check a mere four thousand possibilities.
You could knock that out with a calculator if you were bored.
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Are there any cases of governments having good relations with their Indigenous populations where the majority of the government is not Indigenous? | Coming from the perspective of North America where indigenous issues are deeply problematic, I wonder if there are case studies in other countries that Canada and the US can learn from. How are the Scandinavian countries relations with the Sami people? New Zealand with the Maori? Taiwan with Taiwanese aborigines? My scope of knowledge is limited to N. America and I would love to learn more about this topic from other countries experiences. | You might want to read up on Paraguay, where, iirc, the native people are not in the majority, but an aboriginal language, Guaraní, has official language status and a majority of the population speaks at least some of it. | 16 | 109 |
eli5 why does manure make good fertiliser if excrement is meant to be the bad parts and chemicals that the body cant use | To put it very simply: animals and plants have different dietary needs. What’s waste for the one is nutritient for the other. You can also think about how we breath oxygen and exhale co2, while plants do the exact opposite. | 9,353 | 7,223 |
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How do supercomputers work with many CPU's and GPU's? | Normal computers have problems making SLI run and I think its actually becoming less of a thing lately, yet supercomputers have truck loads of GPU's and CPU's all working together to render some massive weather data or something else?
Why cant I have multiple GPU's and CPU's in a normal PC? Specially the CPU's, since I know SLI for GPU's is at least somewhat a thing. | The codes that are run by researchers on super computing clusters are specifically written to be run on parallelized machines. In the case of CPU clusters, this often means writing very complex code using what's known as the message-passing-interface (MPI). This is a set of standards/syntax that allows you to write a code so that multiple CPUs can be working on the same problem simultaneously. In the case of Nvidia GPUS, the analogous thing to MPI is CUDA.
In your normal PC, 99% of the software you are running is not written to take advantage of parallel processing. The reason why your PC has multiple CPU cores is for multitasking, i.e. assigning different tasks to different cores. This is pretty different from assigning multiple cores to be working on the exact same problem in order to achieve a speed-up.
The reason why SLI isn't really supported anymore is most likely because it's a lot of work for the devs to support a multi-processor project for the consumer market, on top of the fact that no one really needs it. If a game runs fine on 1 GPU, there's no real reason to add a second when you consider things like the fact that the second GPU will increase your power consumption and take up more space in your PC.
Edited for typos | 23 | 17 |
ELI5: What happens to the leg muscles during leg lengthening surgery & recovery? Do they stretch permanently? Is muscle taken from somewhere else? | When bones are lengthened, the stretch on the tissues causes them to grow and lengthen. We know that his happens normally in growing kids as well. Only the bones themselves are lengthened in the surgeries. | 82 | 87 |
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Why did China and India become so heavily populated? | . | A: They're very large countries to begin with in terms of geographical area.
B: They both have multiple large river systems which can support large scale agriculture
C: They both have had centralized governments for millennia. Central governments, despite their bad reputation, do serve to allocate resources efficiently, which leads to greater food distribution and overall population health. This leads to more people, and thus, more children.
D: This increased population millennia ago provided the base for today's population growth. Population growth is an exponential growth model, so a little population difference ages ago will multiply into huge differences in today's population.
In summary, they had a head start. | 26 | 34 |
The Role of Judas in the Bible Dismantles the Belief in a Loving Christian God. CMV. | It's been noticed by many readers of the bible that the acts of Judas are difficult to judge. If Judas had never betrayed Jesus, there would have been no path to the crucifixion. There would have been no resurrection. No redemption. He did betray god, but that was part of the plan. Someone had to do it.
What does this mean for Judas? He was guilty of the greatest sin. He denied the living god. The bible is clear that this is one of the most unforgivable sins, but maybe Jesus would have a more compassionate tone for this man given his necessary role in god's plan and the redemption of all mankind...
>...but woe to that man by whom the Son of Man is betrayed! It would have been better for that man if he had not been born.
No, it appears Judas is not spared. Judas will suffer eternal separation from god. Or "hell" as they've named it. This is from the mouth of Jesus that Judas is condemned. God's plan demanded that someone betray his son. And it appears that Jesus was always aware of who it would be. This wasn't a random individual who would carry this burden. God condemned one man.
>'But there are some of you who do not believe.' For Jesus knew from the beginning who those were who did not believe, and who it was who would betray him.
One person was going to be sacrificed to save mankind. But it wasn't Jesus. The bible makes this clear. Jesus would be resurrected after his death and returned to his father to live forever again in paradise. It was really Judas that would be sacrificed. Judas is the one who has actually lost something in this story. He was the one given to the gates of hell so that all others could have a chance at eternal life. An infinitely cruel act. At least Lucifer was given a choice. Judas never had a chance.
Given this reading of the bible, I don't see how it is possible to consider the Christian god to be a loving or compassionate god. He seems to have designed all of creation to hinge on the eternal torture of one unfortunate soul who is explicitly condemned for his predestined role in it all. CMV. | There are a few inherent flaws in your theory, based upon what appears to be (not to be condescending) limited familiarity with the Bible. First, the damnation of Judas is still undetermined. There is no Biblical indication that Judas was actually damned, but we'll assume that he was for debate.
The traditional understanding of the Bible indicated that Judas, wracked with guilt, took his own life after the crucifixion. That would be reason for his damnation. Under Christian belief, life is the greatest gift God gives to man, and to take your own life is a murder for which one cannot repent.
The other relevant theory is that Judas betrayed Christ at his instruction. Knowing that he needed to die in order for the world to live, Jesus selected Judas to "betray" him. Judas complied, but the guilt was still overwhelming. | 23 | 115 |
AskScience AMA Series - IAmA Bioinformatics guy that works with DNA and protein sequences all day and works on things like the Human Microbiome Project. AMAA! | After posting [mine on /r/battlestations](http://www.reddit.com/r/battlestations/comments/ol31r/scientistcoder_here_vertical_monitor_setup_for/) I had several requests and private messages to do an AMA, so here it is.
For a bit of history, I initially went to school for microbiology & molecular biology. My thesis work was [transposon mutagenesis cloning work in herpesvirus](http://www.ncbi.nlm.nih.gov/pubmed/14742422). My jobs during school were always computer related, and I had started doing database design/coding work when I was 14. When I graduated, I immediately got a job in bioinformatics, which is essentially doing [computer analysis](http://i.imgur.com/VhlQK.gif) of biological data. I was told to learn Perl in a week and get started with data that was coming off the [ABI 3700 sequencers](http://www.noble.org/medicago/Dscn1895.jpg).
Open-source work landed me a job at [The Institute for Genomic Research](http://en.wikipedia.org/wiki/The_Institute_for_Genomic_Research), where the genome of the first free-living organism was sequenced. Here I was able to work on a lot of genome sequencing projects including Aedes aegypti, which was on the [cover of Science](http://www.sciencemag.org/content/316/5832/1718.short) and the [rice genome](http://www.ncbi.nlm.nih.gov/pubmed/17145706).
This later became part of the [J. Craig Venter Institute](http://www.jcvi.org/) before I moved on to the [Institute for Genome Sciences](http://www.igs.umaryland.edu/). There I work on several projects including the [Human Microbiome Project](http://www.hmpdacc.org/), which is an effort to catalog the huge variety of microbes that colonize different areas of the human body.
This work requires a LOT of computing resources (petabyte scale disk arrays, grids with 1000s of computing cores, etc.) and I authored the paper for [Ergatis](http://www.ncbi.nlm.nih.gov/pubmed/20413634), a web interface that lets you build analysis pipelines and run them on large clusters.
I also have a faculty position at Johns Hopkins University, teaching graduate classes in Bioinformatics and do occasional consulting work for different centers.
Phew. AMAA! (The 'almost' is only because contracts legally prevent me from answering ALL questions.)
EDIT: 3:45 EST. Wow - A lot of great questions here. I have to step away from reddit for a few hours (RL + work) but will be back later to keep answering questions. Thanks everyone!
EDIT2: 2 days later and questions are still coming. This has been a lot of fun, and I'm still working on them as I can. Please feel free to post and I am trying to get to them all. Thanks everyone. | I feel like these days there is a pretty big barrier between bioinformatics people, who are often trained in computer science, and biochemists/molecular biologists who are typically experienced in the wet lab.
What advice would you give someone in the latter camp who would like to move into more computational/bioinformatics-type research in the future?
What institutes/companies/academic labs (besides your own!) do you think are doing really amazing work right now? | 18 | 367 |
[Animorphs] Z-space morphing and mass transfer... | Hey there!
So, I'm in the middle of re-reading animorphs, and currently in book 10, 'The android.'
In chapter 9, at the end, Ax mentions that he is worried about the rest of his mass. He goes on to explain that when you morph into something smaller than you, the rest of your mass is transfered to z-space. His worry stems from the possibility of a passing ships shielding system vaporizing his leftover mass.
My question, is on two subjects:
1. What would happen to you? Would you be stuck in morph, permanently a nothlit? Or would it kill you?
2. If, when morphing something smaller, your mass is projected into z-space, where does the mass for larger morphs come from? If the morph technology can simply create mass temporarily, would it not be able to recreate your body once it was destroyed in z-space?
Hopefully we can puzzle this one out together! :) | From memory, a later book mentions "borrowing" mass from z-space for larger morphs.
In terms of what would happen if your extra mass were struck by a passing ship in z-space, obviously you would be sucked into space to be rescued by the passing ship, stay there just long enough to be narratively convenient, and then return back to earth via a hand-waving 'SnapBack' effect. | 12 | 19 |
CMV:If you don't get angry over a pig being killed to make your bacon, you shouldn't be angry over a hunter killing a giraffe bred to be hunted. | People always post these things on social media "That bastard, I hope he dies for killing that majestic animal" when a giraffe that has been bred on a hunting reserve for that purpose is shot and the guy takes a photo with the corpse. But livestock are killed every day and its basically the same thing. Pigs are intelligent animals (https://www.seeker.com/iq-tests-suggest-pigs-are-smart-as-dogs-chimps-1769934406.html) so why are they not afforded the same compassion, apart from what we've got used to in society.
I don't think hunting is good unless you need the food and I have no idea why someone would hunt in a special reserve where its like shooting fish in a barrell, but still its seems like a double standard. | Giraffes and other wild animals are foreign and rare for those living in the Western world.
Hence they've had time to idealize that animal.
It's irrational in the sense that we kill intelligent animals all the time for food and clothing, but it's a logically consistent emotional response in other ways.
We could take it one step further.
Cats and Dogs are widespread and not rare at all. And yet treated like extensions of the family in the United States. Someone will freak out over a person hosting dog fights or eating a dog or cat for sustenance, but not bat an eye at the conditions of livestock everywhere.
It just depends on what the culture deems as important or sacred. For example the cow in India. | 109 | 374 |
ELI5: What is the difference between what dietitians do and what nutritionists do? | Dieticians have to be licensed to use the labels RD or RDN, much like being an RN or an MD. Nutritionists don't.
Nutritionists may have a lot of knowledge and be a big help or they may just be some weirdo who thinks kale is magic and gluten is the devil. If you wind up on a structured diet in a hospital, for example, you WILL be working with a dietician, not a nutritionist. | 1,491 | 856 |
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CMV: I believe that labeling people as “unskilled workers” is a dehumanizing. | Although I have nothing but respect for people working in highly technical professions, I don’t believe calling people “unskilled” is correct. It is my opinion that using this this term could be harmful to self-confidence and perhaps be one of the reasons people stagnant in minimum wage positions.
If a McDonalds worker is “unskilled” would that not suggest any engineer or doctor could walk behind the counter and immediately start working? Isn’t there a point of sale software to learn? Food production training? Customer service skills to develop? I’m not suggesting this takes a graduate degree to learn but they are, by definition, skills.
I think a lot of privileged people who have never worked service industry jobs underestimate just how complicated some of the jobs can actually be. I also believe that conservatives use the term to justify low wages.
Edit: I have worked my share of entry level positions but I am also graduating college this month and will be starting full time work in my field of study within a few weeks. I understand what it means to be labeled "unskilled" but am also beginning to understand what it means to be labelled "skilled".
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | I believe "unskilled" suggests that you don't need any particular training *prior* to starting the job (a degree, work experience, certifications, etc). All you need is on-the-job training that is provided after you are hired. | 59 | 15 |
ELI5: How is the ketogenic diet at all healthy if you're eating lots of fats, which clog arteries? | Put in a very simple way:
Fat does not clog arteries by itself, fat deposits on blood vessel walls as a protective measure, against damaged caused to the lining by other things, mainly, sugar. its a protective measure to prevent further damage to the vessels, and to the blood constituents, the issue is that damage accumulates and so does fat unless lifestyle is changed.
In the early 20th century when people saw clotted arteries with fat, calcium etc, they erroneously assumed that those dietary elements were the factor that was causing the issue, without realising that they were blaming the defensive measure for the problem. Sadly medicine is this giant machine that takes ages to acknowledge information is inaccurate, and even longer to start changing how it deals with it, it takes decades.
And analogy: They saw a huge traffic jam, they saw shinny lights (cops) and blamed the cops for the jam, instead of realising the cops are there because there was a car crash, which is the true factor to blame for the jam.
Ketogenic and vegetarian diets are good to help reduce and even reverse those issues, because you are removing the factors that cause damage to the inner lining of the blood vessels (excess sugar), also helps with diabetes as you prevent constant insulin spikes which lead to insensitivity.
Fats are needed by the body, and quite healthy in themselves, yes, even saturated which is quite important for you, the issue is also how much you eat.
TL:DR: Sugars be the evil, not fat, fat just cool dudes helping you and getting all the blame. | 220 | 114 |
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CMV: Capitalism isn't inherently flawed; the weak can be oppressed by the strong in any system of government (or lack thereof). | Lots of people online seem to think that communism/socialism/anarchy are better alternatives to capitalism, since they will result in greater equality for everyone compared to capitalism. However, isn't any system of government vulnerable to be exploited by those who wish to do so? Power imbalances have always existed in society, between the strong and the weak, between the smart and the dumb, between those with privilege and those without. Unless we address these core inequalities (and preferably not in a Harrison Bergeron type of way), oppression will always exist in the world.
EDIT: I think I wasn't clear in my original question. The CMV isn't that "capitalism is perfect." It isn't. The CMV is "shitty people will exploit others in any economic system." Copying from my response to someone below:
The question is, does capitalism cause exploitation, or does it simply facilitate it? I think it facilitates it, but does not cause it. I'm basically saying the economic equivalent of "guns don't cause murders, but they do facilitate them." You can replace guns with knives, which will inevitably lower the murder rate, but it won't change the fact that people want to murder each other and will try to do so. In other words, other economic systems may reduce inequality, but they will not eliminate it unless you change innate inequality between humans.
Put another way, I say that capitalism isn't inherently flawed because it does not cause inequality. Does it facilitate it? Yes. But it does not cause it.
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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!* | It is possible for one society to have more equality and balance than another. No system purports to be perfect. No one says “let’s transition to system X because it will be a literal perfect world.” Rather they argue for improvements because it will, well... improve society.
Your thought process is kind of a manifestation of the phrase “letting perfect be the enemy of good.” | 15 | 18 |
ELI5: Why did humans evolve mentally when every other species evolved physically? | Why did we evolve for intelligence instead of strength, speed or some other physical trait?
**Edit:** I know I phrased this question awkwardly, I'm not the best with words. And although the question has been answered I still love to read all the new well explained and thought-out responses to this question, but please stop telling me that human's also evolved physically and that animals also evolved mentally. I know this, I'm not oblivious, I just was speaking broadly in the sense that a Shark or Lion's most advantageous quality lies in their strength while a humans most advantageous quality is our mind. | Essentially every evolutionary niche that could provide an advantage got filled by something. It's not that we evolved for intelligence instead of strength, it's that we happen to be the ones that evolved for intelligence so we can even ask the question...other animals went for strength (or speed or camoflage or...).
Humans are, physically, actually quite astounding in terms of endurance. If we're in good physical condition, we can run many other land animals to exhaustion. | 45 | 27 |
ELI5: Why 5G towers and remotely read electricity meters and the EMF they emit are NOT dangerous. | I don't believe they are, but I'm after a convincing argument to use with those who do, that isn't condescending and they might consider.
I work for a power company and get a lot people complaining that they don't want one of those remotely-read (via cell network) electricity meters so close to their kids' bedroom because of "the harmful EMF from the meter".... (while calling from a mobile phone, in their home, which surely also has wifi and a microwave oven).
Correct me if I'm wrong, but this is tinfoil hat shit, right? I know about ionising vs non-ionising radiation, and my understanding is that therefore the EMF these people complain about is harmless and their claims that their kids "have a condition that makes them vulnerable to EMF" are bullshit.
I need to know how to explain this kindly, and hopefully turn a few conspiracy theorists and technophobes.
Googling it just gives me questionable articles that suggest maybe there is some danger. I need cold, hard, truth about why your precious kiddos aren't in any danger from you installing a smart meter. | There's two types of electromagnetic radiation (EMF): Ionizing and non-ionizing.
Ionizing waves have high energy and a short wavelength. Since their wavelength is so short, they can interact with matter on the molecular level. A photon, a packet of light energy, will sometimes collide with an electron and knock it off its atom. This results in the atom having a net positive electrical charge. This slightly changes its chemical properties and can cause DNA molecules not to replicate properly, increasing the odds of cell going cancerous. The immune system is pretty good at dealing with a few cells that mutate like this, but enough exposure overtime will increase the likelihood of developing a tumor. The high energy of the photons can also cause burns.
Ionizing electromagnetic radiation includes ultraviolet light, x-rays, and gamma rays.
Non-ionizing radiation is exactly what it sounds like. They have low energy and long wavelengths. Too long and too low to knock the electrons off their atoms. Though it can cause regular old burns if concentrated in one spot, by say a laser or microwave oven.
Non-ionizing radiation includes radio waves, microwaves, infrared radiation, and visible light.
5G operates in the microwave band, close to the frequencies used by WiFi routers. These devices use relatively low energy that's spread out over a wide area. So where as a laser focuses it in one spot, these are more like a light bulb. There is no known health risk associated with it. Any claims otherwise is strictly psudo-science.
It's also worth mentioning that you are constantly surrounded by both natural and man made magnetic fields. The Earth generates a pretty darn big one. High energy particles also continuously bombard us from space. Any time you run current through a wire, you also generate a magnetic field.
The more legitimate concerns over 5G are security related. Much of the infrastructure is being manufactured by Huawei, a company that has direct ties to the Chinese Communist Party. So there's worries it could be used to bug the telecom systems of rival states. But that's more a geopolitical concern than one that's going to affect the average users. At least in direct terms. | 49 | 39 |
ELI5: Why is IE so hated? Is it really that bad compared to chrome/Firefox? If so, why hasn't Microsoft improved in all these years? | Browsers such as Firefox and Chrome implemented standards proposed by the W3C (a body that sets standards for the web) which make a page to look the same across browsers. Microsoft saw these standards as a threat and did not want the web to be interoperable (i.e. one browser can be replaced with another); so it proposed a different set of web standards that favored them and implemented them in Internet Explorer.
Fast forward ten years: Microsoft's clients, especially large organizations, which use Internet Explorer have still retained their old websites but the outside world has moved much faster. Microsoft cannot do both i.e. adapt to the outside world and support its existing clients, so it tries to do a bit of each leading to Internet Explorer being suboptimal.
As for the hatred towards Internet Explorer, its initial lack of support for W3C standards resulted in website designers having to work hard to display a website in Internet Explorer and all other browsers. Although it is not as true today, the hatred continues.
Edit: Added the last paragraph | 699 | 602 |
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If gravity is a property of spacetime, why are we trying to explain it as a fundamental force? | I feel like I sound like a complete idiot asking this. I should mention I have no real background in physics, so I probably am an idiot.
From what I understand, we describe the strong force, the weak force, and the electromagnetic force as fundamental forces of nature, with each force being mediated by their own boson (or in the case of the weak force, two bosons).
Also from what I understand, gravity is caused by mass bending spacetime around it. To me, it seems that gravity isn't something we should be describing as a fundamental force, and that it should be described as a property of the fabric of spacetime. Are we trying to explain it as a fundamental force because it fits better with the math? | the other three fundamental forces are gauge theories, meaning that they also admit a "geometrical" formulation similar to, but not equal, that for gravity given by general relativity.
There are immense similarities between the other three interactions and gravity. Moreover, the geometric picture and the field picture (the one with the gauge bosons) are really equivalent - barring some global subtleties.
Finally, the unification of gravity with the other forces is almost a necessity, not just something that would be nice. It is likely necessary to build a consistent theory of quantum gravity. We write gravity and the other forces in all possible equivalent ways so that it's easier to understand possible connections when studying theories of everything. For example, understanding how gravity unavoidably arises as the theory of a spin-2 massless boson (the graviton) made it really easy at the time to recognize that string theory included gravitation.
(btw, the weak force has three bosons, and the strong force has eight) | 17 | 21 |
Is literary anti-cognitivism a seriously held position among professional philosophers? | I've recently been reading about literary cognitivism and what I've found is that most (actually all) the papers I have been able to find online have been in support of the cognitivist position. I think I'm quite strongly in the anti-cognitivist camp, but because of the above, I'm worried that this view may not be taken seriously.
The impression I get is that anti-cognitivism is sort of like radical skepticism in epistomology. That is, anticognitivism acts more like a foil for people to explore the question of what we can actually learn from literature, rather than a serious position people actually hold. I think the reason I get this impression is that in the articles I've read, it's often taken for granted that the reader will agree that literature *seems* to have some cognitive value, and it's only the task of the article to explain what this cognitive value could plausibly be. I don't have this initial impression of literature's cognitive value, so I don't find this kind of argument particularly convincing (just because they don't seem to be written with people like me in mind).
I understand that my position would probably be quite radical to people who study literature, but I'm quite curious about what philosophers tend to think. | A common reason why someone might find a view that philosophers consider to be common sense to be unintuitive is that the philosophers have something different in mind than you do. For instance in this case, what kind of cognitive value do you think literature doesn't have but you believe aestheticians believe it to have. | 21 | 75 |
What do blind people see when they dream? Assuming they were blind from birth. | Surveys have been done on this very subject. A lot of the results found that people with congenital blindness often report experiencing other senses while dreaming while almost none experienced any visual dreams.
For example a lot of studies using participants of three different categories (congenital blindness, later onset blindness, and those not blind) reported that those with congential blindness often had dreams where they had sensations of smell, taste, touch, and mostly sound while almost none of them reported having any visual aspects to their dreams at all.
People with later onset blindness after age 1 found that the longer they were blind, the less visual representations they found in their dreams. | 22 | 22 |
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ELI5: How does the human body metabolize stored fat? What can you do to help it metabolize at maximum efficiency (i.e. burn fat at greatest rate possible)? | For example, I see a lot about the importance of drinking water but no real explanation of why. Online sources all speak in technical language I cannot understand or are simply weight loss sites spouting pseudo science. Brilliant scientist redditors please help!
EDIT: Assume that I am already heavily restricting calories. Want to ensure that my body burns the stored fat and not muscle mass (or any other part). | ELI5:
Your body has two main ways to make energy: Carbohydrates, and fats.
Your body normally prioritizes carbohydrates to burn over fat.
If there are no carbohydrates left then it will have no choice but to burn fat (Ketosis).
Your body is not very good at controlling how much fat to burn because it is not its optimal way of making energy. What ends up happening is your body will burn more fat than it needs to because extra energy is better then no energy.
EDIT: People really want to get into the nitty gritty details of nutrition in an ELI5 | 68 | 260 |
AskScience AMA Series: We're Rachel Davis, MD, and Moksha Patel, MD, instructors at the CU School of Medicine. With Rachel's expertise, Moksha decided to undergo deep brain stimulation surgery for OCD. AUA! | Hi, Reddit. We're Rachel Davis, MD, (u/racheldavismd) and Moksha Patel, MD, (u/mokshapatelmd). We're here to answer your questions about deep brain stimulation and OCD, obsessive compulsive disorder. If you are struggling with OCD, you are not alone. Treatments and care are evolving.
Deep brain stimulation or DBS is a rare, invasive brain surgery where electrodes are implanted in the deeper structures of the brain. These electrodes are then connected to generators in the chest that deliver small currents of electricity to the brain, similar to cardiac pacemakers.
About Rachel:
I'm Rachel Davis, MD, associate professor of psychiatry at the University of Colorado School of Medicine. I'm also medical director of the OCD, Obsessive Compulsive Disorder, program and co-director of the OCD surgical program. I've extensively studied deep brain stimulation for OCD and have worked with candidates, like Moksha, before, during and after the process.
About Moksha:
And I'm Moksha Patel, senior instructor of hospital medicine at the University of Colorado School of Medicine where I hold many roles. I've always been high-achieving and busy my whole life; working hard has helped me cope with crippling OCD. I recently worked with Dr. Davis and many others to undergo deep brain stimulation.
I've put in a lot of work with Dr. Davis programming my stimulator settings and engaging in intensive exposure therapy. It's been a challenging process, but I'm happy to say I'm feeling relief; I am more engaged in life and can travel, go out with friends and go about my day to day without being completely stuck in my head. I'm also working toward an MBA at the University of Colorado Denver.
Links:
+ [OCD Ruled Moksha Patel's life until a rare surgical procedure changed everything](https://news.cuanschutz.edu/news-stories/ocd-ruled-moksha-patels-life-until-a-rare-surgical-procedure-changed-everything)
+ [DBS Research for OCD: patients with comorbidities](https://news.cuanschutz.edu/news-stories/ocd-patients-with-comorbidities-respond-well-to-deep-brain-stimulation)
We'll begin answering questions at 9AM MT (8AM PT/11AM ET/15 UT). AUA! | For Dr. Davis:
Second Sight discontinued technical support for their eye and brain implants in 2020 when the company collapsed. Patients with those implants now can't repair them.
Does the success of Dr. Patel's treatment depend on the ongoing existence and benevolence of the company that made his implant? How do you ensure that your patients will be able to maintain and program their implanted devices for the rest of their lives? | 67 | 668 |
ElI5: please, What’s the difference between crystal and glass? | There are two different ordinary uses of the word crystal.
The first ordinary use of the word crystal is a orderly arrangement of molecules of a single molecule. Two common crystals found in almost every bodies homes are salt crystals or sugar crystals.
The other ordinary use of the word crystal is a special type of glass. This type of glass has a different ‘recipe’ than window glass or glass used for drinking or bottles. The crystal glass has a higher refractive index, so it is better at refracting sunlight into its constituent colors. Glass made with the ‘crystal recipe’ (often made with lead compounds) is used for prisms, chandeliers, anything where you want the glass to be ‘sparkly’ or colorful. This recipe is also used for ornamental drinking ware and special bottles used to contain, for example, brandy. Crystal glassware does nothing to improve the flavor though it does enhance the visual presentation. | 70 | 38 |
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[Full Metal Alchemist] How is Alchemy triggered? | In FMA, when the brothers try and resurrect their mother, their hands are already on the circle, and then they decide to begin the alchemical process like magic. Similarly, Alchemists who wear their transmutation circles/arrays on some sort of apparatus can trigger and control the alchemy at will.
Does it work like some sort of magic? Is one of the key components to utilising alchemy the human soul, maybe that's a hypothetical reason why human souls are so valuable in Alchemy? I'm not sure, I'm probably reading into it, but it really does seem like there's a magical element that's completely overlooked. | Alchemy is triggered by touching the transmutation circle with intent to use it. Different symbols in the circles have different effects. However a single circle isn't limited by the quantity of stuff it can transmute (which is how Armstrong and Mustang are able to create walls and explosions of varying sizes). But the elemental ratio has to be there or else you get a rebound. But that's still not all of it.
Each person has within them a "Gate of Truth", it is that gate which allows for the performation of Alchemy. Not everyone knows of it, and only those who have performed human transmutation have seen it.
Circles are necessary for **all** transmutations. Even Edd's "clapping" counts as a circle. What happens when you see the Gate of Truth is you get all the knowledge of the world crammed into your skull at once (not that you'll remember any of it at more than a subconscious level, since the human brain can only hold so much). What happens when Edd claps is that his arms form a circle for an instant, as he visualises what he wants to transmute. | 31 | 26 |
ELI5: Why are empty glass bottles harder to break than full bottles? | Was throwing a couple empty bottles around earlier today, and noticed that it took a lot more force to break than a full bottle did, why is this? | 1. Full bottles contain more weight, so at the same speed they hit with more force.
2. Energy waves transmit much more strongly through water than through air -- the force of the impact will be carried all around the bottle quite effectively. | 16 | 16 |
CMV: Safe Space subreddits do more harm than good. | To refine this idea: In my opinion subreddits (particular ly political ones) which actively ban or delete user contribution which challenge the ideas espoused by it do more harm than good by creating echo chambers in which missinformation is more likely to spread.
Missinformation and echo chambers can cause harm, primarily through causing people to vote and see the world in a way that is not supported by facts and bringing in candidates who platform on falsehoods. Furthermore missinformation and fake news can cause real harm in some extreme cases such as the debunked [pizza gate](https://en.m.wikipedia.org/wiki/Pizzagate_conspiracy_theory) incident where a man shot up a popular pizza restaurant under the false belief that he was saving children trapped in a sex slave ring.
Obviously subreddits should have moderation, but I personally feel this should be limited to removing obvious troll and unconstructive posts. In some political subreddits, stating factual information which happens to highlight flaws in ideology or simply fails to "tow the party line" within the subreddit can warrant a ban because the subreddit is meant to be a "safe space" and contradictory information is unwelcome.
By banning users who attempt to correct or debunk falsehoods which further the subreddits agenda, the subreddit gives a platform for fake news and missinformation to spread and cause harm.
Furthermore, I am of the opinion, that if you are secure in your beliefs, then surely you should be secure enough in them to defend your worldview from opposing viewpoints. (Hopefully this doesn't come back to bite me in an ironic way.)
Banning / silencing people presenting reasonably backed up contributions which challenge your viewpoint is something that should be relegated to an Orwellian dystopia, not a platform for free speech and open sharing of information such as Reddit.
| > if you are secure in your beliefs, then surely you should be secure enough in them to defend your worldview from opposing viewpoints
Perhaps safe spaces are more about providing respite from constantly having to defend your position. | 37 | 30 |
CMV: Tape style White Out is far superior to liquid style White Out. | Hello! Today I would like to present to you the concept that using a tape style white out is better in nearly every way than using liquid white out. My credibility on this matter is that I screw up a lot when I write and have to fix a large amount of mistakes.
Pros of Tape:
1) Distributes controlled and evenly.
2) Can write over it immediately, no drying time.
3) Don't have to unscrew a cap, wasting time.
4) Can't spill all over my papers and make me sad.
Pros of Liquid:
1) Can make little ghost finger puppets on your fingers when you're bored.
Seeing as I can make ghost finger puppets at work in other ways, I render the only benefit of liquid white out to be null and void. However, I do accept my view may be flawed, as many liquids are pretty cool and there may be benefits to the liquid white out I have not considered.
CMV!
(EDIT: Formatting!)
_____
> *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!* | Pros of Liquid:
1. Takes time to dry giving you time to reflect over your mistake and plan on avoiding it in the future.
2. Depending on the type of applicator you get it's fun to play with. With the pen style, you can feel like a tattoo artist. With the brush style applicator, you can feel like a painter. With the foam tip, you can feel like a nurse or doctor prepping a patient for surgery.
3. Can be easily wiped away if you apply it wrong without risk of tearing the paper.
4. Smells good in a "this might be making me high" kind of way. Even if it's just a placebo effect, it's pleasant.
5. The final product looks smoother.
6. You can customize the size and shape of the white. You aren't limited to the standardized tape size which means it works better for smaller font sizes or narrower lines.
6. There's no risk of the paper getting scrunched up.
7. The pens have no risk of spilling. Or if you like to live you life on the edge, the bottles have the risk of spilling. Your choice. | 16 | 71 |
Is there a genetic difference between the races? | I'm arguing with someone on another subreddit and we've pretty much exhausted google. So I'd appreciate some expert help. Thanks!
* Is there a significant genetic difference between the races?
* Is one race more intelligent than other races? | There are genetic differences between races, but most of those differences are relatively insignificant. Human populations are actually relatively low in diversity, compared to other animal species. It's been speculated that the human population was bottlenecked down to as few as maybe 5,000 people only about 50,000 years ago by the Toba supervolcano eruption. Two mice species that look very similar to each other (to our eyes) can actually be more distantly related than humans and gorillas. And they can successfully interbreed.
So compared to that, our racial differences are pretty much trivial. Also, our ideas about race actually correspond pretty poorly to the actual genetic data. The most egregious example of this is just lumping african populations together. There is more genetic diversity contained in african populations than there is in the rest of the world combined. An average swede is more closely related to the average mongolian than two africans that may live in the same city.
As for intelligence, the current thinking from genetic association studies and twin studies is that 40-50% of intelligence is determined by your genetics. The rest is environment. However, given the degree of genetic diversity in place, you can't make a blanket statement that "africans are dumber than europeans". Africa contains so much genetic diversity, it will contain individuals that are "genetically" much smarter than europeans, as well as individuals that are less smart. The distributions of those and averages may be different, but it's hard to define the relative contributions of genetics for someone who grows up as a sub saharan tribesman and someone who grows up in sweden with free education. There is very little in common between their two educations, so it's very hard to make an IQ test that encompasses everything they both are good at. | 37 | 18 |
Is there a national/ international database for viruses, bacteria, fungi, etc that affect humans? | I’m imagining something like DNA held in a crime case. They can’t find a match for it so a record is kept, and vice versa if you’re convicted of a crime your DNA is now on a database for future checks.
Now back to my original question. If you present to hospital with a cough that leaves you struggling to breathe for days on end. The staff swab you, take a sputum test, even do an endoscopy to take samples. All come back negative for anything they have “on file”. Are records of these samples kept for future testing? Do private pathology labs have access to an international or national database? If so, is it mandatory to report everything that comes into the lab? | Check out databases like NCBI's GenBank, EMBL's ENA, etc. Basically, if you have an previously unidentified disease of some fungal/bacterial origin, your doctor can work with a lab (or may have their own lab) to run a lot of tests that can identify the type of organism. They can also sequence the organism and then publish a case study on your disease, and deposit that sequence in NCBI (say) using a relatively standard procedure. | 38 | 91 |
ELI5: Why is rice so readily available and cheap? | I've traveled around Southeastern Asia a bit and seen rice paddies first hand, as well as have read a bit about how difficult life is for rice farmers. It seems to be incredibly labor intensive and somewhat low yielding, so I don't get why 1) there seems to be so much of it really available, and 2) it is such a cheap crop. Can someone ELI5? | I am going to look at this from a smallholder/ traditional farmer point of view
It does appear to be incredibly labour intensive, but rice comes with one incredible advantage, you can flood the fields and plant the rice plants in the mud, and the rice will grow for the first few weeks of its life in the water, so while planting and harvesting looks backbreaking, apart from that you have 3 months or more where you just need to control the water flow.
This means no plowing, no digging, and more importantly no constant weeding or bug patrol for the farmers, it also means that they don't need tractors or teams of oxen, or to spend money on weedkillers and pesticides. | 10,022 | 15,291 |
Since time is not absolute, does it make sense to describe the age of far away galaxies in years? | It turns out the effect isn't that big in most real-life situations, but there is a convention we can use if we really want to be more careful when we talk about time.
Time runs at different rates depending on the relative velocities of objects, and also based on the strength of gravity fields. However, you have to be going pretty close to the speed of light (relative to some other observer) to experience time at a significantly different rate, and you have to be basically right next to a black hole or neutron star for gravity to make a big difference. While we do experience time at different rates, for the speeds that most galaxies & stars are moving at, this comes out to a tiny fraction of a percent. It's usually way finer than the precision we have in measuring distances anyway, so it really doesn't matter, and we can basically assume that time is pretty much simultaneous everywhere - we don't care about a few days out of a few hundred thousand years.
But if we want to be more precise, we use the cosmic microwave background as a base. The CMB is moving relative to us at a very consistent velocity, and it is very uniform across the observable universe. So it's a convenient frame to use if we want to define a convenient "universal" time frame. It isn't *actually* universal - it's just fairly constant over a very large volume of space, and that makes it a useful convention. | 46 | 37 |
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ELI5: How do they construct underwater supports and structures such as bridge supports and boat ramps? | There are several techniques that can be used. As /u/Earhacker mentioned you can build the structure or build components for the structure on land and then sink them in place. The English channel forts were built this way.
Other options include building on site either underwater using concrete that will harden underwater or using a caisson - a water free container that you sink in the water and build inside it.
Side Note: The Brooklyn bridge in New York City used caissons that while successful left many of the workers handicapped because of decompression sickness.
One option is to build a dam around the construction site. Then build normally and remove the dam and flood the site when construction is finished. | 10 | 17 |
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Is it possible to transform martian soil into fertile soil through bacteria and fungi? | You’d have to find a way to thicken the atmosphere first. If we had bacteria or fungi that could function in a near vacuum. Add to that the problem that water boils at about 10c on Mars, and you’ve got a bit of a problem. | 26 | 43 |
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How do the scientists estimate mass of galaxies based on their brightness and colour? | I've recently watched YouTube video called Dark Matter's Not Enough by The Royal Institution and I heard there the explanation of dark matter. Presenter said that dark matter idea came from discrepancy between two estimates: there seems to be 5x more mass in galaxies based on their rotation speed than when estimating mass based on their brightness. I know a little bit of science and I could image measuring mass based on rotation speed but you would need to know how large that galaxy really is, so that I imagine is a bit of a challenge.
The bit that blew my mind was estimating galaxies mass based on star brightness. How such thing can even be possible and how can estimate measurement error for that?
The 5x times discrepancy suggest to me that there might be huge error in there that is not accounted for, meaning that measurement may be incredible inaccurate.
| So the vast majority of normal (baryonic) matter is contained within stars, and obviously stars give off light. We can work out the ratio of how much mass a star has compared to how much light it gives off - this is called the mass-to-light ratio. For example, our Sun is a fairly typical star and has a mass-to-light ratio of 5133 kg/W.
This ratio differs depending on the exact size and composition (stellar class) of the star, but the figure above gives a reasonable "average" value for a population of stars. Therefore if you measure the brightness of a galaxy, you can then work out the mass by simply multiplying by the mass-to-light ratio. As to the errors in this calculation, I'll have to defer to someone more knowledgeable. | 18 | 95 |
[Green Lantern] What specific power does each lantern ring give? | All of them give relatively similar powers, but some have more unique properties than others.
All of them grant the ability to travel safely through space at superluminal speeds, including a personal force field that provides life support, universal translation, and the ability to create beams of energy that can be shaped according to the wearer's desire. The further they are from the "center" of the spectrum with green, the more influence they exert over the wielder-- yellow and blue rings mostly amplify tendencies that are already there, while red, orange, indigo, and violet rings can dominate the wearer's personality entirely.
* The energy produced by red rings is highly corrosive and intermingles with the blood of the wearer, forming an acid-like substance they can spew from their mouths in battle.
* Orange rings steal the identities of those the wearer kills, enabling them to create and maintain constructs of those entities that serve them, and can absorb constructs from other rings to replenish their energy.
* Green and yellow rings don't have many unique abilities, but offer a greater degree of fine control that is extremely difficult with other rings.
* Blue rings are the hardest to create constructs with, but are highly adept at healing and can create a feedback loop with green rings that supercharge both, and can dampen the influence of red, orange, or yellow rings, as well as create images that reflect the hopes of a target, as well as recharge from the hope of those around it.
* Indigo power rings reflect the abilities of other rings they're in close proximity with. They also heal, but can also cause pain to those who have caused pain to others, and can teleport over extreme distances.
* Violet rings have similarly precise control to green and yellow rings, and can also create crystals in which a living being can be held in stasis and slowly shaped into an ideal wielder for another such ring. Their constructs are immune to the absorption ability of the orange ring. They can also teleport and resurrect the recently deceased by drawing power from the heart of someone who loved them. | 30 | 16 |
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If a person with a certain communicable disease dies of it and is buried, do the said pathogens continue to live, multiply and spread in the soil? | By extension, like how vaccination improves herd health, shouldn't incineration be a preferred mode of disposal of the dead rather than burial? | This will depend on the pathogen in question. Some examples:
Anthrax can survive in soil after the host is dead, although the bacteria aren't actively multiplying (instead, they form spores).
Prions can also persist in soil ("survive" is the wrong word here because they're not alive). | 23 | 22 |
I know a little bit about relational databases like MySQL. What are noSQL databases? How do they work and how does that differ from relational databases? | Whereas a relational database is typically thought of as a collection of tables, with columns, and rows of information referencing other rows of information in other tables, the structure in which a noSQL system stores data is markedly different. If you're familiar with any programming languages, you can think of the way this information is stored as a dictionary. Or JSON. Essentially an N depth hierarchy of key-value pairs.
That's the difference in how they store data, individual systems on both sides have distinct requirements and considerations for things like distribution, scaling and redundancy. | 10 | 46 |
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ELI5: What is happening in your brain when you struggle to remember something and it finally comes to you? | The brain recalls things by first filtering out memories that it deems irrelevant, to try to narrow down the remembering process. Sometimes it accidentally filters out what you were trying to remember, so you can get really close but not quite remember that exact thing. After a while, when you focus on something else, the "filter" goes away / resets and if you try to remember it again the brain gets it right that time. | 24 | 26 |
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[Harry Potter] Where do new spells come from? | I remember in one of the books it said that you had to get a new spell approved through the ministry or something but I don’t remember the details.
When a new spell is made, is there a memo that goes out to all wizards/witches? Do they have to “update” their wands somehow or does it just work on all wands after approval? | Wizards experiment through trial and error to form new spells often using Latin root words related to their desired effects to produce a result. It's a dangerous practice that can end in death e.g. Mrs.Lovegood.
Wizards may publish their new spells in periodicals or via their own published spellbook. Some, such as Snape, may keep them a secret just for themselves.
Wands don't need to be programmed. If you know the words, wave and have the skill you can cast it. | 32 | 23 |
Is there more to Utilitarianism than decreasing suffering? | I know. I know there is literally more to it. What I'm looking for is the source of this concept of morality.
All to often I argue with people that claim their ethics are based in utilitarianism. I'll ask them why and they will say "decreasing suffering is the purpose or the goal of morality". Something to that effect.
Easy argument to dismantle in my opinion because if it were true that the only structure to morality was to mitigate suffering then shooting people in the head would be the ultimate moral exercise.
Is there something I'm missing or is there a flaw in the argument of the college utilitarian? | The idea that the only goal is decreasing suffering is a particular interpretation of negative utilitarianism that fell out of favor for the reasons you specified. Positive utilitarianism includes increasing happiness. And most people presume that people have overall more positive experience than pure suffering in their life, and so being alive is preferable and so killing them is wrong.
Different forms of utilitarianism expand on this in ways. For instance, some happiness might be better than others, which explains why being alive is positive, since enduing some suffering is worth it for the benefits. Or maybe happiness is the main, but not the only metric. Other things may be independently valuable. Or maybe preference is the metric. | 11 | 17 |
CMV: There is not a substantial amount of flat-earthers. Genuine believers are practically nonexistent. | I’m not here to debate whether the earth is flat, I’m saying that practically no one believes it is. I’m defining substantial amount as being any amount of people that is indicative of our culture or worth worrying about. It’s hard to put a number on though. Basically I believe no one is raising their kids to believe in a flat earth as some popularly circulated facebook posts claim, that no one is doing serious research, that there are no legitimate organizations not flooded 95%+ with trolls, and that “some people even think the earth is flat” is not a legitimate example of people’s modern gullibility.
Anyone who seriously considers a flat earth is either 13, clinically delusional, living without education, flexing their debate skills for the sake of debate, or 90% joking 10% playing devil’s advocate. 99.999% of flat earth memes are trolls. Some are elaborate, but trolls nonetheless. The only “I can’t believe they think that” here is @ the people who believe the crazy posts. I actually have seen people worry this marks a new dark age.
People believe crazy things all the time, yes, but those things usually have legitimate benefit to them. Believing the earth is 10,000 years old discredits evolution, shames the “atheist academics”, upholds biblical literalism, ect. Believing one race/sex is biologically superior to another upholds a hierarchy. Believing vaccines are dangerous gives an illusion of control over the genetic lottery.
You can believe practically anything and still think the earth is a sphere. | I think you need to add a small percentage are those that are desparate. One flat-earther put it best, "If the earth isn't flat, it means it isn't special, and our existence is a fluke and essentially meaningless."
That small section just denies the truth because a round earth makes them feel incredibly small. | 19 | 40 |
ELI5: Why do the Nordic countries seem to do so well in like, everything? | They have low corruption, low inequality, very democratic, high standard of living, low obesity, etc.
And of course, if they aren't so great, why are they the go-to example of an ideal country? | Northern European "Calvinist" work ethic and ability to defer pleasure, coupled with culturally homogeneous populations and large amounts of natural resources (in Norway's case, oil).
I expect this to change as their culture dehomogenizes due to immigration. | 66 | 45 |
How should I handle a fellow student that is hijacking our lab meetings? | My five fellow students in marketing and I have a lab meeting with our advisor every two weeks in which we discuss papers in our field. I love our meetings because they have very high quality discussions and i want to keep it that way.
Our department is mixed with several other business related fields, including management info systems, which is different in terms of theory, methods, and journals. One of the MIS students, X, in the department has a project that she wants to be more marketing-related, although it absolutely is not. She has been asking our advisor for his advice and he graciously did. However, ever since this started a year ago, X has become a complete nuisance. Examples: she asks our RA to design her studies for her (phd students should do this themselves) and takes up at least four hours of meeting time with advisor every week whereas the more junior students get far less (X has two advisors of her own in her own field, and our advisor has four students himself). This was not my problem so i let things be.
Now, however, she has started attending our lab meetings, which does affect me directly. Im ok with 'outsiders' attending, but only if they keep the discussion within the field. X is not doing this by consistently asking unrelated questions, refuses to alter her way of thinking, refuses to acknowledge other viewpoints, and talks over others. As a result, the quality of the discussion has plummeted.
I am the most senior student in the group, so I have something to say about what happens in these meetings if it really affects the group. I do not think our advisor can / will do anything about this (he is working with her so competing interests). He is also very polite and sincerely wants to help those that ask for his help, and she capitalises on this.
I am not afraid of confrontation and plan to confront X directly, but i want to come up with a smart strategy that involves not burning bridges with advisor or anyone else except X. What can i do to make this situation better? | Write and circulate an agenda for each meeting. This should include a timeline for each topic. Appoint a firm but fair chairman (yourself) to regulate the discussion according to what is on the agenda. | 12 | 19 |
ELI5: For me to make money does someone else in the world have to lose money | If for example i have $1000 more than last week does that mean that collectively everyone else is $1000 worse off? | The simplest way to understand this is through an economic concept called Pareto improvement.
Any trade is a Pareto improvement if both parties regard themselves as better off for having made the trade. Imagine buying a hamburger. You prefer having the hamburger to having the $2 that it costs (otherwise you wouldn't have bought it and would have kept the money) and the restaurant prefers selling you the hamburger than keeping it (because they make a profit).
By buying a hamburger, you have slightly increased the total value of the global economy, by improving the efficiency by which resources are allocated. The same principle applies to the vast majority of trades - if both parties didn't think that they would be made better off for making the trade, then they wouldn't do it.
The vast majority of trades in a functioning economy are Pareto improvements. Every time one of those trades takes place, the total wealth of the world improves slightly, because the underlying resources have been allocated in a way that provides a greater amount of utility. Not all of these transactions are ideal, but they're better than no transaction at all.
Situations in which trades are made with no Pareto improvement are sufficiently unusual that they have a specific name in economics, a "market failure". Examples of market failures include things like monopolies (where someone can control a market and coerce people into making unfavourable trades) and pollution (where a third party is made worse off by an economic activity). | 34 | 90 |
In delayed choice quantum eraser experiment, what is the purpose of the lens before D0 ? | I have no experience in the field- just trying to understand the experiment conceptually.
The paper says "The use of lens LS is to achieve the
“far field” condition, but still keep a short distance between
the slit and the detector D0". I think I understand purposes of every other setup except the lens before D0 , what does it suppose to do/what is far field condition?
Link to the paper: http://arxiv.org/pdf/quant-ph/9903047.pdf | They want to take the Fourier transform. There are two ways to take an optical Fourier transform. You can just let the light propagate in free space, which means it propagates into the "far field." However, for the far field condition to be met with only free space propagation, the propagation distance often has to be unacceptably long, as in ~2000 meters for visible light and a 1-in aperture/beam size. The second way you can achieve an optical Fourier transform is with a lens of focal length 'f', where you place the object and "imaging" plane a distance '2*f' apart with the lens in the middle. This also achieves the Fourier transforming action, but doesn't require the huge distances. This is a very common thing in optics; you can read more in Goodman's "Introduction to Fourier Optics." | 17 | 89 |
[Star wars] in revenge of the sith what is the big lava planet factory for | On the lava planet at the end of the movie, what is the factory/refinery/building that obi wan and darth vader are fighting on used for | A very young and volatile world, the intense geological activity interferes with scanning, making it useful for unsavioury types that want to stay hidden.
There are also mining facilities, mostly for gathering a special mineral that is commonplace in the lava there, which is what makes the lava on Mustafar have a lower temperature than most other places. Still, repulsors have to be used to deflect heat away from facilities and those working in the field. | 30 | 18 |
[Spiderman] What are some of Peter Parker's most impressive academic feats? | We all know he's a web slinging hero, but some might forget he's also a somewhat accomplished young scientist.
I struggle to name specific scientific achievements and am hoping y'all have some to share. | Peter is an intelligent person, but he doesn’t have many academic feats because he doesn’t know what to manage his time, prioritize tasks, and delegate tasks.
In Superior Spider-Man, Doc Ock implants his consciousness into Peter and forces Peter’s consciousness out to die. Ock decides to be a better Peter and a better Spider-Man (Superior Spider-Man). Ock finds out that Peter is a very intelligent person, but can’t manage his time and prioritize tasks. Ock proceeds to build Spider-Bots to patrol the city for him, which alerts him if he is needed, so Ock (in Peter’s body) can return to college. He delegates the Spider-Bots to contact him for Spider-Man level emergencies or to call the police/fire department for smaller emergencies.
He also brutally beats villains to deter other villains from committing crime, saving Ock even more time. Eventually Ock (in Peter’s body) graduates and creates Parker Industries. Parker Industries develops a lot of different kinds of technology. Towards the end of the Superior Spider-Man storyline, Peter gets his body back and Ock’s consciousness gets transferred to a different body. Peter continued to develop a few different kinds of technology until he had to destroy the company. | 79 | 73 |
How do axolotles breathe? | I know that the spikes on their face are like gills, but I was wondering more about how that works in comparison to a mammalian respiratory system? | The gills have tiny blood vessels and a high surface area that allow the blood to get really close to the water so that oxygen in the water can diffuse into the blood and carbon dioxide in the blood can diffuse into the water. | 13 | 18 |
Best Hard Copies of Books | Hello!
I'm primarily a student of English Literature. Norton Critical Editions of texts in this field are great because in addition to the text, they include hundred pages or so of contemporary critical analysis and other texts (letters, journal entries, other primary documents) providing context.
Is there an equivalent philosophy publication? For example - the full text of Nietzsche's Also Sprach with some analytical essays included.
I'm sorry if this isn't the kind of post that's allowed, I really don't know where else to ask and the googling I've done hasn't been fruitful. | It's extremely dependent on the specific text - at least for works in translation. If the work is in translation, it is normally necessary to do some research online as to which translations are well received. For Nietzche, is doesn't matter how good the supplemental materials are if the translation is off. Once you know what translation you want, you're normally pretty limited in terms of the editions available.
If the work is not in translation, there's not a huge difference. Philosophy texts tend to be presented on their own, sometimes with an introductory essay. So long as the copy of the text comes from a reputable publisher - a University Press, Routledge, Hackett, etc. - any included introduction should be serviceable. Though it is always, of course, worth checking on the specific reputation of any author whose commentary you are reading.
If you want secondary literature, you normally have to go to a separate edition. These texts again vary widely based on the specific content - as these things tend to be in philosophy, where interpretations of thinkers vary greatly - but a good starting point are the companions put out by Routledge or Cambrdige. But, again, do some research online for specific recommendations first. | 16 | 43 |
[ELI5] In the dark, why can we see an object when using the peripheral vision, but looking direcly at it we can barely see it? | There are two types of light receptor in the eye: rods and cones. Cones are colour sensitive but aren't good in low light conditions, and they're concentrated around the centre of your field of view in order to give you good colour vision during the day. The peripheries of your eye have mostly rods in them, which are much more sensitive to light, so in low-light conditions you'll see better at the edges of your vision than directly ahead. | 20 | 16 |
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ELIF: What is the link between heart problems and teeth? | Bacteria can very easily enter the blood stream through the gums. Most of the blood vessels in the human body have one way valves that allow blood to flow one direction but not back the other way. This prevents blood from getting trapped in our limbs. The blood vessels in our head and neck don't have one way valves this makes it easier for bacteria get from the mouth to the heart. Also the route from the mouth to the heart is very short compared to other routes blood takes in the body. This means that our body doesn't have time to destroy the bacteria before it gets there. This is where the science gets a little foggy. We don't know exactly why there is a correlation between gum/tooth disease and heart disease but there is. The best theory I've heard goes as follows. There is plaque in our arteries. Not the same kind of plaque on your teeth, this plaque plaque is made up of cholesterols that bind together and attach to the arterial walls. This is what causes strokes and heart attacks when it completely blocks off arteries. It has been shown that people with gum/tooth disease have more of this plaque build up in the carotid artery. Samples of this plaque have shown that bacteria from the mouth ends up in these plaque deposits. The leading theory is that the bacteria grabs onto these cholesterols and plaque buildups and makes them larger and more potentially dangerous if the break free and go to the brain or heart where they can block the artery and cause a stroke or heart attack. | 10 | 19 |
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ELI5: How are pre amps for microphones or guitar amps programmed into digital plug-ins to accurately recreate the tone you'd receive from the actual device? | The designers create a mathematical model of how the amplifier works in theory. Then they compute that model for your given input on the computer to generate the output.
With amplifiers the big thing they're after is something called non-linearity.
Linearity means if A goes in and X comes out, B goes in and Y comes out, than if A + B goes in you'll get X + Y out.
With an amp, if A goes in you *should* get G×A out, where G is a fixed constant. One of the most common things to happen in an amp is something called "clipping." Clipping happens when G×A is greater than the voltage supply for the components. The amp will "clip" off the top of the signal at the voltage supply level. So if you wanted to model simple clipping you could use a piece wise function
B = G×A, GA <= V max
B = Vmax, otherwise
There's your simple clipper model for a preamp. The issue though is that electronics don't just act non linear depending on supply voltages. In the case of clipping, the signal doesn't get cut right off exactly at the supply. It sort of gets rounded off as the signal gets higher. So to get an accurate sound you need a better model.
Being able to create a good model isn't trivial. It's based both on circuit analysis and physics as well as theoretical signal processing. There's good money in it so the big companies don't share how they figured it all out. | 50 | 307 |
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Why are the major producing oil fields located where they are? | Oil fields are where they are as a due to the location of ancient organic-rich basins. Why were the organic-rich basins there? Tectonics, they generally drive the placement of landmasses.
For oil to be extracted, it needs:
- a source rock: often these are shales with high carbon content, the remains of ancient accumulations of algae and other bio-material
- a heat source: the rock needs to be "cooked" to chemically transform the bio-material into the gases and liquids that make up natural gas and crude oil. This can only occur in a narrow range of elevated subsurface temperature. Too high and you'll burn the organic matter, too low and it won't transform into high-quality petroleum.
- a "storage" rock: the oil needs to be held within a porous media so that it can easily be extracted, and so that the yield in a given field is high.
- a cap rock: usually the transformed liquids and gasses are imiscible fluids that don't combine well with one another or water. Since petroleum is less dense than water, it wants to float to the surface (where it would quickly degrade). To keep the oil stored in one place, it needs some kind of "pocket" to be trapped in. These are usually low permeability antiforms or salt diapirs.
In summary, oil fields are in places that were once basins with lots of biological activity. The basins had to be turned into rock, cooked, stored, and capped in order to create petroleum and prevent it from degrading. Furthermore, if a field has experienced these geologic phenomena, it still needs to be economically extractable, which is dependent on proximity to the surface, engineering, infrastructure, politics, cost of crude, etc. | 16 | 36 |
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How do astronomers determine masses of planets and other celestial objects? It's not hard to scale their volume, but it's not enough to find mass out. Do they define prevailing materials and substances and speculate on the density to calculate mass using volume or what? | Usually masses are determined by observing the orbits of things around them, in the case of planets it's usually the planets' moons that are used. A lot of stars are in binary systems, and the binary orbits were used to understand the relationship between brightness and mass, which can be used to determine the mass of solo stars. For more distant things like galaxies, we can see how much the light of even farther objects gets deflected by gravity, and use that to calculate the mass. | 15 | 15 |
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ELI5: The business model of banks. How do they make money? | People loan you money, you pay them a small amount of interest, you loan other people money they pay a substantial amount of interest, the difference between the interest rates minus your costs is the profit. | 30 | 16 |
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CMV:Democracy is bad because it gives power to the stupid majority, instead of the expert few. | I'm no expert on politics, or the full ins and outs of how democracy is meant to be structured. However, I feel like a system that uses the majority opinion to decide things is a poor way of making decisions.
Take a look at [the bell curve.](http://robert-craven.com/wp-content/uploads/2015/02/6a00d83451df4569e201a3fce9ba57970b.jpg)
This is a well known statistical distribution found everywhere in nature, from IQ, to height, to GPAs. In a system where the majority opinion reigns, the result is that the "average performers" have a louder voice than the experienced, initiated people who actually know how that particular issue works, the common pitfalls, the longer term implications and detailed knowledge of all of its considerations.
Most people don't know *shit* about how an operating system works, or even just computers in general. They click any flashy link, download every suspicious file and happily run obviously dangerous executables, infesting their computers with viruses, useless tool bars, and malware. But someone with a degree in computer science and years of experience working with computers has an enormous advantage in the use and operation of a computer, expertly changing complex settings to his preference, fixing it when it breaks, and generally making informed decisions concerning its use in getting it to do precisely what he wants it to do (much better than the average person).
It's a similar situation with a lot of other fields. Most people don't know *shit* about field X, because they don't have a degree in it and years of experience doing it. Their thoughts, decisions, and opinions on the concerns of that particular field will be woefully inaccurate, generally, and pale in comparison to a professional. For example economics. What business does the average lay person have in medalling with the worries of economists ? Healthcare ? Research? Laws governing the use of computers and the internet ? (SOPA).
Not all issues are as polarizing as one that has clear experts and clear laypersons. For example, disputes between classes of people, the rich vs the poor, etc. But on the issues that DO have clear experts, the majority should not be making those decisions.
| >Not all issues are as polarizing as one that has clear experts and clear laypersons. For example, disputes between classes of people, the rich vs the poor, etc. But on the issues that DO have clear experts, the majority should not be making those decisions.
experts don't agree in politics or philosophy on a great many issues, which issues do you believe have clear experts and how would these experts be represented in government (based on sole expertise in a single issue)? healthcare, research and ethics more broadly do not have consensus in a great many areas, even among experts.
What is best ideally also often fails in practice. The majority has to live with the implications of policy.
| 11 | 16 |
ELI5: Why does cooked food generally taste better than raw food? | Aren't we just supplying heat to the food? What causes the drastic difference in taste? | Different factors play a role here. What happens to food if you apply heat? I'll name a few things:
Fat melts, becomes liquid or creamy. Makes the texture nice and pleasant.
Sugars caramelize.
Starch granules pop and gelatinize, therefore become smooth and soft, have a better mouthfeel.
Proteins (with some sugars) go through the maillard reaction which is still not understood in its entirety. It's the reaction which causes the browning of meat, for example.
(Unpleasant-ish) textures change. Eggs and doughs solidify - meat and hard vegetables become softer and nicer to eat and chew.
Some toxins are denatured (e. g. beans and some mushrooms need to be cooked to be edible).
And of course one point could also be that we've grown to prefer the taste of cooked food during our evolution, as some of these processes make foods more digestible and therefore provide an evolutionary advantage. | 44 | 26 |
ELI5: Why are snowflakes symmetrical? | How does one side of the snowflake know what what the other side looks like? How do they grow six identical segments? Shouldn't the shape of each segment be random? | The formation of ice crystals is dependent on the precise atmospheric conditions. Because each arm is experiencing the same atmospheric conditions, each arm forms the same way.
This is also why no two snowflakes are alike: each one follows a different path to the ground and experiences different minute fluctuations in temperature, humidity and airflow, all of which impact the crystal formation. | 71 | 46 |
Why is the concept of infinity so hard to grasp? | Let's say, theoretically, that there is life after death. In this "afterlife" you will live... Forever. Permanently. To no end. Whenever I think about how this would just keep going and going and never finish is like a strain on my brain. But why is it so difficult to comprehend? | Human experience is limited by certain conditions. We are unable to grasp anything that transcends the limits of time and space, because the world is given us through these forms, and cannot be given in any other way. The infinite would transcend these limits.
At the same time, infinity seems necessary, as we cannot imagine a border that does not separate.
This is answer is found in Kant. | 18 | 16 |
In a classroom, (especially science, engineering and mathematics), there are students that clearly don't understand the material, yet they never ask questions, even if the teacher asks if there are any. Why don't they ask questions? | Many times, they ultimately end up doing poorly on quizzes and exams. | Three reasons (that may overlap somewhat):
1) Not knowing what question to ask. If you don't understand something, it can be hard to formulate a question that makes sense and will increase your understanding. That's why so many questions you do hear in a classroom are garbled and make no sense, and as a consequence often the teacher fails to understand what the student is missing, or the teacher may just subtly scold them for asking a poorly-formed question.
2) Knowledge that further discussion isn't going to help anything. It may be that the teacher is not good at explaining things in different ways, or hat the concepts being taught are sufficiently complex that they can't be absorbed in a single sitting/lecture, but require further study. In this case, to ask the teacher to repeat his or herself is just wasting time that could be spent covering more material.
3) Maintenance of an image of a good, smart student. Students want to appear to be good and smart in the hopes that teachers will grade them higher. This often works, though less often in STEM fields. | 32 | 17 |
ELI5: Why aren't humans regularly de-wormed like pets are? | Wouldn't it make sense to do this just in case? | In industrialized nations, parasitic infections are rare. Between wearing shoes, not stepping in poop all the time, washing hands, cooking food thoroughly, and other changes of modernity, it's harder to get worms than it used to be.
In the rest of the world, people have parasitic worms, and that's a fact of life. Antiparasitic campaigns, which can include regular de-worming, have been attempted in the developing world with some success. Like any public health intervention, it comes down to risks and benefits--some parasites are pretty harmless, and antiparasitic medicines aren't always harmless (consider the rash of ivermectin overdoses in the U.S. recently.)
Interestingly, there's a fair case for RE-worming some humans. Our immune systems are well-adapted to having some worms on board and keeping them in check. In the modern world, a lack of parasites to help calibrate the system seems to be part of why allergies and autoimmune disease have increased dramatically in the West over a short period. Purposely giving people a relatively harmless worm, AKA helminth therapy, may be an effective treatment for autoimmune diseases like Crohn's and ulcerative colitis. | 85 | 34 |
ELI5: Is being Jewish a religon or is it a race ?? | You can be Jewish (religion) by birth or by choice. You can be culturally Jewish , but not religious if you have a Jewish mother. Racially there are Jews of all nations. Most think of European Jews (Ashkenaz), but there are Black Jews of Ethiopia, Indian Jews (Menasha tribe), North African (Sephardic) and even Chinese Jews from the time of Marco Polo.
| 20 | 22 |
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Does cellular communication use radio waves or microwaves? | May be a stupid question for a subreddit way more scientific than I could ever be, but I'm having trouble finding defined ranges for both radiowaves and microwaves and so I'm also having trouble categorizing cellular communication into either one. I was always pretty sure it was radio but now I'm having doubts from what I'm seeing on the internet.
(I sort of guessed the flair, my bad if it is incorrect) | Both. “Radio waves” is a general term that encompasses all wavelengths (frequencies). The term “microwave” implies a certain frequency range, usually starting around 1GHz and extending to maybe 30 GHz. Frequencies above that are generally termed “mmWave”. So all microwaves are radio waves, but not all radio waves are microwaves. | 46 | 32 |
CMV: I don't believe kids get "inspired" to pursue careers in science and engineering. I think the efforts to do so are well intentioned but futile and instead should be focused on helping the kids find what interests them. | We all have innate interests. I really don't like baseball. Some people love baseball. I don't think we can raise a kid to love baseball if he doesn't have some natural inclination.
I think the same goes for anything, including science and engineering. Yes our world needs scientists and engineers. But to think that we could try to inspire Kobe Bryant (when he's a kid of course) to love physics seems crazy to me. I think we should just try to help kids find their passion instead of trying to influence it. I guess my point is 'passion is innate'. No one becomes a scientist without being passionate. Soo change my view.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | It might be true that trying to force someone to become a scientist doesn't work, but clearly the act of exposing a person to something they have never seen before will increase the likelihood of them being interested in it and getting into it.
Showing a child about circuits and what you can do with them might not make him or her become an electrical engineer, but not showing them is almost certainly going to make sure they aren't one.
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ELI5: How are people in physical professions (eg construction worker) able to grow large muscles but many people recommend to have rest days if you're going to the gym if you're trying to build muscle? | It's recommended to grow muscles fast and where you want them. If you'd lift every single day for 10 years you'd grow muscles too.
Also construction workers have rest days too, the weekend for example. Or just doing a different work another day. | 59 | 40 |
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ELI5/How does gut flora vary from country to country and from first world to third world countries? | On one hand you’d think it’s better in richer countries that have less disease. On the other hand, people in third world countries seem capable of eating some things first world country people can’t handle.
So my guess is it’s a mix of things? I’m wondering how it plays out.
I looked it up and what I found was either way over my head or very specific to one spot.
Thank you. | How is kind of a broad question. Lets first answer why.
The gut microbiota develop mainly right after birth. During birth, breastfeeding etc the infants gut gets populated with microorganisms. The parents microbiota are well adapted to local conditions and get passed onto the child. During childhood those microorganisms and our body learn to cooperate and deal with local food and other microorganisms that are present there.
Obviously, if you move across the world both your body and your microbiota are suddenly panicked. They have to deal with food they have never seen and have to deal with microorganisms they have never encountered. This frequently sends the signal: "We might be getting food poisoning!" and the body flushes your gut resulting in a diarrhea.
Some places have more/different local microorganisms. If say, you are from Europe you might be used to microorganisms X and Y. Your body knows how to deal with them or knows they are harmless. If a European then goes on a trip to Egypt, where X, Y and Z are common, you might expect frequent visits to the toiler. This happens so often some people refer to it as the "Curse of the pharaohs"!
On the other hand, the Egyptian natives moving to Europe would already be used to X and Y, while Z is simply not present, so the risk of getting a diarrhea is smaller for them. If they stay in Europe for a long time though, their body might forget about Z and panic if they ever move back. | 26 | 35 |
ELI5: Why are sticky things sticky? | I was eating a cupcake and the frosting was sticking to my fingers, and it made me think: What makes stuff stick (e.g. adhesive, syrup, etc.)? What is going on with sticky substances that make them act the way they do? | For those kinds of foods, it's the sugar. The molecular formula for sugar allows it to make fairly strong bonds (Hydrogen bonds) with water. So whenever you mix the two, they bond together, or it becomes "sticky". In addition, you hands have a lot of moisture/sweat on them, so if you hold sugar in your hand, the sugar will bond to the moisture and stick to your hand.
EDIT: grammar
EDIT2: extra word. | 120 | 240 |
If black is the most effective color for light absorption, why are plants green? | thanks! | The reason plants use the frequency of irradiation that they do has to do with the machinery plants use to harvest energy from light. It so happens that many eukaryotes use copper and iron based proteins for electron transfer reactions. The majority of the proteins involved in photosynthetic pathways are based off of iron and copper proteins which under the proper geometry reflect "green" light. | 53 | 54 |
PhD Student Pitfalls and Blunders? | This type of question is my favorite question to ask because it teaches so much. In your personal experience and in your observations what mistakes/pitfalls or blunders do you see Phd students making? Could be rare mistakes or very common or somewhere in between!
I would prefer answers in STEM but other fields would have valuable input as well! | - Treating your PhD like a class project
People will actually read your work and question everything you write.
- Lack of realistic goals and deadlines
No, you're not going to finish all your experiments in one week.
- Not talking to your advisor
This differs between labs, but they're supposed to be there to help and guide you. Try to get their input as often as possible.
And most importantly
- Seeking perfectionism
A finished thesis is never perfect and a perfect thesis is never finished. It might be ok to delve into interesting aspects of your project but know when to limit yourself. Going too far into the rabbit hole might not bring substantial benefits and delay your graduation significantly. | 21 | 18 |
ELI5: Why do soldiers bother taking POWs? | In addition to laws and conventions, it's also a tactical decision.
If you're a soldier, and you know the enemy are about to overwhelm you, you have two options. Surrender, or go down fighting and take a few more of the enemy with you.
If you know the enemy is likely to accept your surrender and take you prisoner, you're probably a bit more likely to go with that option. By taking prisoners, armies save the lives of their *own* soldiers, too.
There's a story that during WWII, German parents would tell their children to surrender to Americans, because they take prisoners and treat them well. Much safer than actual fighting. | 19 | 16 |
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ELI5: Why do some Bluray movies look like crap? | I get annoyed when I rent a movie from a bluray disc from Netflix and the resolution doesn't appear to be anywhere near 1080. Furthermore, sometimes it doesn't even fill up the screen. What's going on here? | >These are characteristics of the transfer of a film, not the encode. The two are very different. The transfer is the scanning of the film source to a digital representation. This is where things like contrast, color fidelity, etc. come into play. They can be fixed after the scan, but if you've ever scanned anything, you know that it's much easier to do the scan properly to begin with. If you do a really poor job scanning, you might never be able to fix the issues.
>A poor encode will display the following artifacts: color banding, macroblocking, and lack of sharpness. You see these things because there just aren't enough bits to go around--the source is being bitrate starved. The encoder has to compromise somewhere.
>Other digital artifacts include lack of detail from excessive use of DNR and halos around the edges from excessive edge enhancement. These lie between the transfer and the encode. They have to be added somewhere between the two, and aren't particular to the transfer or the encode process.
ELI5; sometimes they just stretch the movie out if it's old | 24 | 33 |
ELI5: How is the USA PATRIOT Act still functioning, despite constant criticisms about its unconstitutionality, as in why hasn't the Supreme Court overturned it yet? | In order to challenge the constitutionality of a law you have to have standing to do so - the simplified version of that is you have to be able to prove the law has harmed you or infringed on your rights or (in some rare cases) that it is likley to do so.
So far most of the challenges to the USA PATRIOT Act have been rejected on standing grounds, the Court finds that people lack any proof that they have been harmed by the law. Since the most controversial provisions of the law have to do with what the government can do in secret, it turns out to be very hard to prove you have been harmed by the law (and when you can, that evidence may be in admissible on state secret grounds). So you lack standing.
TL:DR if you can't prove you've had your rights violated because the violation was secret, you can't challenge the violation because you can't prove it happened. | 40 | 88 |
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ELI5:How can the Federal Government demand colleges handle sexual assault under Title IX? | It seems to me that the language on Title IX has no bearing on sexual assault. | Title IX provides that schools receiving federal money (effectively all of them) are required to ensure that the environment does not become hostile to students.
The argument the Feds have used to force the schools to comply with this logic is that they (the schools) have an affirmative duty to remove people who pose a threat or by their presence create an ongoing hostile environment to other students. Students who claim they are survivors of sexual assault also claim that interacting with the alleged abuser creates a hostile environment that limits their access to the campus and thus to furthering their education. | 16 | 40 |
ELI5: Why in the military do some people get the best medical care in the country at places like Walter Reed while other military personnel and veterans get awful horrible care at VA hospitals? | A lot has to do with where and when your injured.
Active duty and in combat: If it's sever enough you'll go to Walter Reed, otherwise you'll be in a different military hospital, some excellent, some okay, and some barely passable (just like any large dispersed group).
No longer active duty but with service related injuries, you go to the VA.
Now imagine the differences in both numbers of patients and age/health of those patients. Military hospitals will generally see younger people with acute issues (broken leg, arm blown off, a cough, etc.) Where as VA hospitals will see older parents with chronic conditions. Plus there are millions more veterans then active duty service members. It's not a surprise the VA has issues since they are almost always underfunded and over worked. | 16 | 17 |
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ELI5 I read laser beams get wider, like a few feet wide by the time they hit the moon, Is that a manufacturing limit, or just something about the physics of laser light? Is a perfect laser beam that doesn't get wider possible? | It’s a property inherent to laser beams. Most lasers have a shape called a Gaussian and that type of beam has a properly known as divergence that is basically the angle at which the beam spreads as it travels. The divergence can be controlled but has a minimum that is determined by the wavelength and the beam diameter.
So yes, you can get small divergence but it requires a large beam size and challenging optics, but it’s always going to have some spread. | 3,782 | 5,323 |
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If there are multiple universes existing, is it theoretically possible for two universes to expand into each other? What would the consequences be? | This depends on what you mean by "multiple universes".
If you're talking about multiple *observable* universes, then yes, but since an "observable universe" is an observer dependent construct, not a lot happens. This is just the statement that as our observable universe expands, we'll be able to see more stuff.
If you're talking about multiple universes in the sense of the Many-Worlds Interpretation of quantum mechanics, then no. These "worlds" already occupy the same physical space and shouldn't really be thought of as "other universes".
If you're talking about multiple universes in the sense of large extra-dimensional string-theories, then again no. Expansion is an effect that occurs within the 3-dimensional spatial slice of a 3+1 dimensional spacetime; it doesn't in any way bring two such universes "closer". That said, there *is* a sense in which such universes (called branes) can collide. In fact, there are some speculative models in which our own "big bang" was actually the result of a collision between two such branes. | 17 | 20 |
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What range of atmospheric pressure changes can be sensed by the body? | Some of my joints swell up when atmospheric pressure drops before a storm. It only happens sometimes, and I’m not sure why. Is this influenced more by the delta in pressure or by how quickly the pressure is changing? | The ears when they are hearing sound can detect changes as small as 20 micropascal. And you could go ridiculously high because if your body is obliterated by an explosion, you did technically notice the pressure change. | 16 | 18 |
Why is 0-14 used for the pH scale? What are the highest and lowest pH substances both in existence and theoretically possible? | The pH scale is related to the molar concentration of hydrogen ions. Normal water has a H+ concentration = 10\^-7, therefor the pH is 7. Technically, pH is the -log10 \[ hydrogen ion activity\]. The scale goes beyond 0 - 14, but only uncommon substances are outside this range. Battery acid is pH = 0, meaning the H+ activity is 100%. Pure liquid lye drain cleaner is pH = 14, so the H+ activity is 10\^-14 (very low), and the OH- activity is very high.
Hot saturated solution of sodium hydroxide can reach pH = 16. Very concentrated HCl solutions have pH = -1.1, and some waters from the Richmond Mine in California are reported at pH = -3.6. | 70 | 56 |
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ELI5:Why are ISPs not considered monopolies? | E.g. Only Comcast (Argh!!) is available in my neighborhood and just keeps raising the price and now is making us sign up for a contract | They are often considered monopolies in the regions they serve. Cable companies are very often regulated as natural monopoly 'utilities' by municipal utility commissions. The laws governing how these organizations regulate are often old, archaic, and have been manipulated by industry lobbying to make it difficult for them to gain serious concessions on issues like price and service. Cable television, in particular, has historically been seen as a 'luxury' utility and has been given greater discression on how to conduct itself. | 48 | 180 |
ELI5: how does the autofocus work in a DSLR camera? | I know it's something related to the camera changing the focal length until it obtains the sharpest image but does it know which one is the sharpest image? | It evaluates the sharpness by edge detection. It finds the line that divides the highest brightness and color change, then changes the focus to create the sharpest, most abrupt change across the line. They get more sophisticated by testing several areas and more recently, prioritizing face detection. | 14 | 19 |
CMV: Every lawyer should serve at least 2 years as a public defender | Similarly to how fresh medical school grads don't go straight into being a doctor, they become a resident first. They help treat real people in hospitals and are extra medical personnel instead of the hospital relying on only MDs.
We need a similar system for lawyers. After you graduate law school and pass the bar, you serve at least 2 years as a public defender. Of course, they should be paid a decent salary just as medical residents are.
Ultimately, the goal of this is to have more public defenders and BETTER public defenders. Currently, public defenders are overworked and tend to be people who do this out of passion or couldn't get the top tier law jobs. Under my proposed system, this would result in lower case loads, more attention to the cases, and all lawyers from the top of the class to the bottom would be working. Of course, if a lawyer is incompetent, they would be fire, just as a an incompetent medical resident would.
Too many people, even innocent ones, end up in major debt fighting for lives when their public defender is shitty. We cannot have a fair and working legal system when one side (the state) has adequate representation but the defendant does not.
I am open to changing this view because I understand it's a big order and no one likes being told where to work, but it's not the only job that has mandatory apprenticeships.
I look forward to hearing your arguments! Thanks! | I think the challenge here is while all doctors who continue practicing medicine have something to learn from working in a hospital, even if they ultimately go into private office practice, many lawyers will not work in criminal law. How does two years as a public defender preparer somebody who will go into civil suits, contract law, estate law, bankruptcy law, and the like? | 68 | 93 |
What's the difference between water drying and boiling on a molecular level? Is the reaction same between different types of liquid? | I've always thought that water turns into gas only after boiling because the molecules spread out. How does water that's just sitting there dry out? | On the surface of any liquid, there will be a few molecules with more energy than the others, simply due to random jostling. If one gets jostled hard enough, it will leave the surface and evaporate.
Boiling is a more extreme form of this process. The jostling is so intense that molecules _throughout_ the liquid, not just on the surface, have a chance to be jostled into high speed. If they're under the surface, they join with other fast-moving molecules to form a bubble, effectively creating a new surface for more boiling (homogeneous nucleation).
Incidentally, the creation of a new bubble is helped if there is any speck or flaw in the vessel where fast-moving molecules can agglomerate. This is called heterogenous nucleation, and it's why tossing salt into a pot of boiling water will make it seem to boil more fiercely. | 161 | 343 |
[Physics] Is it possible to make a mirror that only reflects black and white? | I know that mirrors are only supposed to reflect the colors, but is there any way to make a mirror only reflect shades of grey? Like, using a filter or some kind of film on the mirror?
I mean something like [this](http://imgur.com/2NxkLgk)
Edit: Thanks Guys, I guess that means that we have to make a digital solution :D | You cannot do this using current pure optical solutions and here is why. First off, you must think about what a standard mirror does in order to accomplish what it does. It reflects light based on the interference patterns that are caused by the material properties of the mirror when photons are absorbed and elastically scattered. Each frequency of light can penetrate slightly different depths before the point of reflection, or the point at which only constructive interference occurs. This constructive interference is precisely what allows light to be reflected at the "reflection angle" that most people are familiar with mirrors. At every other angle, relative to a source and an observer, destructive interference occurs, removing the light in other pathways. Because mirror reflection is interference-driven, it requires phase-matched light, and so it only occurs at each frequency of light irrespective of the other frequencies (for the most part).
Now comes the clarifying bit. Photons which are coming from a source and hitting the mirror at each microscopic point, have a specific color (i.e. red, blue, green), based on the frequency of the individual photon. When that photon "reflects" off of a mirror surface, it retains its frequency and returns at an angle based on the interference pattern. It is at this point that the mirror would somehow have to be able to return one frequency of a photon, and, using interference, turn it into an array of broadband frequencies that is the grayscale. What this would mean is that the interference pattern, which is phase-based and therefore frequency-based, would be occuring for all visible frequencies at the same angle at the same time from one single photon. This is impossible purely optically (currently), because the energy gap would be huge. That is, much more energy coming out of the mirror than going in (of course that could be account for on the field-intensity level).
That being said, it is totally possible to do this using a source/detector hybrid scheme, rather than a mirror. Or you could do it digitally, as someone else pointed out. | 26 | 59 |
Can the equations of fluid dynamics be used to describe/model the flow of electrons? | In low-Reynolds number flow (slow or constricted flow), fluid circuits can be treated the same way as basic electrical circuits, with pressure instead of voltage, flow rate instead of electrical current, and a fluidic resistance that is analogous to electrical resistance except depends differently on geometry. The analogies generally break down if you move away from this regime. | 1,345 | 3,575 |
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CMV: In most situations, there are practical reasons to hire an able bodied person over a person with disabilities. This is not ableism, if it is, then there's nothing wrong with ableism. | I hope I use the right terminology in this post. Using the correct terminology can be a minefield because there's never a consensus on these things and terms inevitably fall to the euphemism treadmill.
While I certainly believe persons with disabilities are not any less deserving of respect or dignity, I firmly believe they are limited in some ways and a practical employer should almost always hire the able bodied person, given that they are equally qualified.
I don't want to use the one armed ditch digger example because that one is too obvious. Obviously, a two-armed ditch digger will do a better job than a one-armed one. Ditching digging is the job description and I think everyone will agree that there is no issues with hiring the person with two arms.
Let's look at some more difficult scenarios. For each scenario you will imagine you are a compassionate, just and competent employer. You are also presented with two candidates who are equally qualified in every way, except one has a disability.
**Scenario 1:**
You are hiring a web developer. Candidate A is able bodied and Candidate B requires the use of a wheelchair. Your workplace is an old building that has been grandfathered out of Accessibility laws. In order to hire Candidate B, you will need to build a ramp to your building at your own expense. You hire Candidate A.
**Scenario 2:**
You are hiring a game developer. Candidate A confides in you that he quit a previous job due to overwork and stress. He says he was working 100 hours a week. He says he is fine to work 40 hours a week.
Because you are a fair boss, all your employees work 40 hours a week. However, since you are in a competitive industry with tight deadlines, sometimes you fall behind. You don't rely on employees pulling 100 hour work weeks to meet deadlines, but sometimes there are unforeseen delays. You hire Candidate B because though your employees *shouldn't* be working 100 hour weeks, you recognise that it's sometimes inevitable and you want someone who can go above and beyond.
**Scenario 3:**
You are hiring a secretary because the previous one is leaving. The previous secretary took it upon himself to water the plants in the office. This is outside the job description but it took the previous secretary 3 minutes a day to do and he was happy to do it. Candidate B has mobility problems and thus wouldn't be able to water the plants. You hire Candidate A.
In my opinion, there were practical reasons for the employer to choose the able bodied candidate in each of the above scenarios. I'm not sure they would have survived a lawsuit if the employer has disclosed their reasons to the rejected candidates but morally, to me, they pass the smell test.
How is a person with disabilities supposed to find a job then? I don't have a good answer to that question. But I don't think that should be the employer's burden either.
edit: fixed several typos.
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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!* | >In **most situations**, there are practical reasons to hire an able bodied person
You are argue "most" situations. Yet all examples are basically edge cases.
A. Very few buildings are grandfathered out of access laws. And fewer and fewer remain. Edge case.
B. You admit that scenarios where 100 hours weeks are required are an edge case.
C. Watering flowers? Very few employers would realistically give a shit about who waters the flowers. Edge case. A janitor who has to come in anyway can do this job for 50 cents extra.
So all you have shown are minor edge cases that would not apply in vast majority of situations. So how is your view about "most situations" supported?
It seems like in vast majority of cases - there is no legitimate business reason to exclude an impaired person. | 32 | 51 |
ELI5: How can birth control methods still cause weight gain even if your healthy diet and exercise remains consistent? | So birth control works by using two hormones; progesterone and estrogen. The estrogen will make it so that your ovary will not release an egg. The progesterone works by making the natural fluids in your uterus thick so an egg cannot implant. The weight you gain is most likely just water weight. If it's a larger amount of weight, it may not be the birth control causing it. (I work in the medical field) | 26 | 21 |
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If E=mc², does energy have gravity? | I know for most classical measurements like gravities of astronomical objects, energy would be nearly inconsequential to the equation.
But let's say there's a Neptune sized planet in deep space at nearly absolute zero, if it had a near-pass with a star and suddenly rose 200-400 degrees K, would that have any impact on it's near field gravitational measurements? No matter how minute? | The short answer is yes - the rise in temperature would affect the apparent gravity by a little bit. How little? Well, math!
Let's take your Neptunian planet, and raise the temperature by 300K instantly. Now the mass of Neptune is ~10^26 kg, and if we roughly assume its all hydrogen (in reality its about 80%) then using a bit of simple chemistry corresponds to about 6 x 10^52 particles of hydrogen. The thermal energy is roughly given by E = NkT where T is the temperature, N the number of particles and k is Boltzmann's constant; which leads us to an increase in thermal energy of E = k x (6 x 10^-52) x (300) joules. A conversion to mass using E=mc^2 gives m = 2.76 x 10^15 kg. Which looks huge, and is definitely a change in the effective mass, but really is minuscule in comparison to the total mass of Neptune (11 orders of magnitude smaller). It's pretty close to the mass of Mars' moon Deimos, for example. | 88 | 164 |
ELI5: Why do lightbulbs take a small moment to power on in certain cases, but turn off instantly? | Fluorescent light bulbs (and Compact Fluorescent bulbs) need to do a couple of things before visible light is produced. A high voltage electrical arc passes through the tube, which separates electrons from their parent atoms in the gas in the tube. This creates a situation where a lower current can then travel through the gas (since the electrons are now free to move about). That allows UV light to be produced, which excites the phosphor coating on the inside of the tube, generating visible light.
The arcing process is what takes a moment.
Incandescent bulbs need to heat up the filament to glow white hot, but that takes only fractions of a second normally. And the mechanism used in LED bulbs is even faster. | 11 | 15 |
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How do we know that space/ the universe is expanding and not matter "shrinking" in relation to space? | How do we know that the universe is expanding and not matter "shrinking"? I have no physics background so as far I can see the observable effects would be the same: As matter gets smaller/is shrinking, but space is'nt, it would seem like every galaxy is moving away from us. Also there would be no need for dark energy etc ...
This might be a ridiculous question, but I just could not find an answer myself how we know for certain that this isn't the case. | When observing very distant objects, we observe the phenomena of red-shift, where the light waves from the galaxies and quasars have be stretched as a result of the expansion of the universe. Objects which are further away appear to be moving away much faster than objects which are nearer--the red-shift is more stark. If matter were simply shrinking, the effects of red-shift would come solely from the actual movement of distant objects from us. Nearly everything in the universe is moving away from us and some of these objects are "moving" faster than the speed of light, which would be impossible with the shrinking matter theory. | 14 | 33 |
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