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ELI5: Why are most of the fastest sprinters and best marathon runners of all time black? | There has only ever been 1 white male to run under 10 seconds in the Olympics 100m and he was the first of purely European descent. Is it something about the skin colour geners that affect the potential of an athlete? | Not the color of the skin, but the genetics and culture. The pigmints in your skin don't give you super powers, but there are some muscle traits that are passed down genetically, a form of natural selection. Some of the african cultures are more closely linked to hunting tribes rather than a culture that focuses on agriculture - like European civilizations. This caused a need for people who could run fast for longer, and people who could do this would provide for their family better, and thus they could have more offspring. | 26 | 35 |
Peer-review: how to know a request is legit? | Hello everyone! I have received an email asking to peer-review a paper. This is my first approach (if you exclude obviously predatory journals) as I am still a PhD student.
I was approached via my personal email, which I used to publish a thesis after I lost institutional affiliation, so I know which paper the editor has either read or seen the abstract of. Reviewing this paper as an ‘expert’ is a bit of a stretch, and whilst it’s broadly in my area I couldn’t really comment on who the author has neglected to mention etc.
The journal seems legit? My area is so interdisciplinary, I probably draw from 100+ journals so it’s not unusual to not recognize a journal’s name.
I am hoping for a little guidance as to whether it’s okay to accept, what the general norms are of doing this and how to identify when I should and shouldn’t turn these offers down beyond the obvious of totally different subject and clearly predatory.
Thanks! | 1. View several issues of the journal to see if people you recognize have published in it. This will help you assess if it's legit.
2. Ask your advisor.
3. It is probably not legit, though this depends on your field.
4. Ask your advisor.
5. If you don't feel comfortable reviewing it (you said you're not the expert they're looking for) *and* if you judge the journal to be legit, politely decline. If it's not legit, mark the email junk or spam and move on.
6. Ask your advisor. | 96 | 81 |
Can someone explain to me the term "Hypothesis-driven research"? | I know what a hypothesis is and what its role is in research (I am talking life/medical science here). But the term hypothesis-driven research never really I never really caught.. Sounds to me that one would focus extremely on its hypothesis, disregarding any other not directly related indications, data, whatsoever.
Give the fact that the term I only cam accross when people used it in a positive way, I really must miss out on something here.
Thanks in advance! | It is the difference between exploratory research -
"We wish to perform these tests and see what we find (we think it will be interesting because ...)"
and hypothesis driven research -
"We think that we will find that X corresponds to Y when we perform these tests. (this will strengthen the hypothesis that...)"
It is the difference between not having any idea what is going on and looking to answer a specific question.
*edit* theses -> these | 30 | 15 |
ELI5: I read online something about how 85% of Earth's species are still yet to be discovered. How do we know that we've only discovered 15% of all species when we don't know what "all" is? | Take a bunch of samples from all over the world, look at them really carefully and count how many different species you find in them.
Some of them you will already know, and some will be completely new.
If in 1000 samples, you find 100 different species, of which you only knew 15 before taking the sample, then you now have your answer as to why we estimate only 15% of species have been discovered. | 41 | 53 |
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ELI5:What happens if you never repay your loans? | There are two types of loans: secured, and unsecured.
A secured loan is a loan for an object that has value, like a house or a car. If you stop making your car payments, the lender takes back the car. Legally, when you took out the loan to buy your car you gave them the right to do that.
An unsecured loan is just cash, there's no specific object. An example of that would be credit card debt. If you fail to pay your loan, they can try to collect the money, if it's a lot - by getting a court order to garnish your wages or take money directly from your bank account. But if the amount isn't worth it, they'll just ruin your credit rating, making it impossible for you to get any future loans for the next ~7 years.
If you didn't actually commit fraud, then you won't go to jail. Failing to pay back a loan is civil, not criminal, and there are no debtor's prisons.
If you owe so much money that there's no way you could ever pay it back, you can declare bankruptcy. The way this works is that the court takes your remaining money, divides it among everyone you owe, then declares all loans paid off. You start over from scratch. You're left with items you need to survive like a car and a basic apartment, but if they're extravagant you may be forced to sell those and get something more modest.
Fun fact: prior to the Affordable Care Act (Obamacare), the #1 cause of personal bankruptcy was medical bills. Obamacare may not be perfect, but it definitely helped this situation a lot - far fewer people are bankrupted by medical bills today.
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ELI5: Why does transparent materials like water act like mirrors? | When you look at a lake, or a water puddle, it reflects everything just like a mirror. How does it do this, if the water is totally see-through? | When light hits a boundary between one transparent medium (e.g., air) and another (e.g., glass or water), some is reflected and some is refracted. Usually only a small percentage is reflected, except at very shallow angles, but often even that small amount is enough to produce a visible reflected image. A good example is looking out a window at night, when it's dark outside but brightly lit inside. The window will appear to act as a good mirror. If you look out the same window in the day time the reflection is still there but it's much harder to notice because it's competing with the very bright view outside. | 25 | 52 |
Is math only a human construct; that is to say, do humans discover math, or do we invent it? | There are some intermediate positions here, namely that it is constructed in a non-arbitrary way due to constraints on how we experience the world. The idea that mathematics is a way our minds structure reality is called *intuitionism*.
The most popular position in philosophy, including among philosophers of mathematics, however is that it is discovered in a more robust sense. That is, the objects that are discussed in math exist as abstract objects. This position is called *Platonism*. | 69 | 108 |
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CMV: Almost nobody actually wants you to be yourself. It is a lie they tell you and themselves to feel good about themselves. | I have been thinking about this one on and off for a few years now and I think it is about time I have a proper debate on it and get some more viewpoints. People do not want you to be yourself at all, they want you to fit in a narrowly defined socially acceptable version of "yourself" and the only "weird" that is allowed is the socially acceptable forms of it. People say this is untrue but they constantly show it to me with their actions. It is merely a lie they tell themselves to feel like they are good people without doing any of the work of actually taking that advice to hear. Now I do not mean this in a judgmental way, just as an observation. Here is an easy lump of proof: let's say I think eating bugs is perfectly acceptable. I would not eat them raw just like I would not eat raw meat, but a nice worm burger does not sound like a bad idea to me. Are you disgusted? I am sure many of you if I did this in the break-room at your work would ask me to stop, but yet there is not one rational reason to as bug meat is provably safer than regular meat (and probably healthier than regular meat). Now not to detract from the argument too much with this example (it is just an example, one of many and I see similar examples happen to other people all the time who do things I am not particularly fond of myself but feel I have no right to judge) this is proof that most people do not at all want people to be themselves because who they are makes them uncomfortable which gives them the right to judge and dislike others... apparently, but I am sure if you asked them they would go right ahead and say everybody should just be themselves. It is merely a hypocritical cliche statement that society has adopted but very few ever take to heart.
So there you have it. Change my view Reddit. I am eager to see more viewpoints on this.
EDIT 1: thank you all for taking the time to discuss with me as I do my best to be patient. It is time I sleep but I will be back to answer more responses tomorrow.
EDIT 2: thank you all for your time I feel this has helped me expand my view a little further but also feel there is more that could be said and discussed. I will continue to respond to posts here and try to get back with 24 hours at least.
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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!* | "Just be yourself" is typically advice given in specific situations. When a high school student is struggling to fit in, intensively studying the fashion trends and entertainment interests of their peers, and following suit in order to be cool, and they're actually making themselves uncomfortable in this effort.
"Just be yourself" does not mean "Do everything you want to do." It means "Don't force yourself to be someone you're not."
For most people, their "true self" is not going to be a socially unacceptable individual. It's going to be someone who wears alternative clothing, or who makes art out of controversial subject matter. Most people do not want to eat bugs.
Now if there is someone who desperately wants to eat bugs? Yeah, most people aren't going to "approve." But this isn't a situation where that advice applies, and it is an outlier among deviations from the social norm. | 14 | 30 |
The Iraq War was both just and necessary. CMV. | Alright, I think it's time that I had a proper discussion about this. **I firmly believe that the decision to move Iraq, the Middle East, and the region into a post-Saddam Hussein era was a moral and legal imperative for the United States and the international community and that force of arms was the only feasible way to accomplish that.** That's my position, in a sentence. I hope the post title doesn't misrepresent that.
Here's why:
1) There are four reasons for which a sovereign state may lose or sacrifice its sovereignty under international law.
* It has invaded or occupied a neighboring state.
* It has violated or proposed to violate the Genocide Convention
* It has displayed promiscuous and frivolous behavior with (or plainly violated) the Non-Proliferation Treaty
* It has actively harbored internationally wanted terrorists and gangsters
Iraq is the only modern state to have violated all four of those. It had attempted to annex Kuwait and make it part of Iraq, as well as engage in a pointless border dispute with Iran that cost thousands of lives. Saddam had issued a direct order to exterminate the Kurdish people of Iraq. He did this using biological and chemical weapons. Further, he maintained a department of state for the concealment of nuclear weapons. Although none were found during the invasion, he had stated that he wished to rebuild the nuclear program once the sanctions ceased. Finally, his country was the homebase of Abu-Nidal, Zarqawi, and the Achille Lauro hijackers from the PLF.
This meant that the international community had a duty, as well as a right, to remove the regime from power by any justifiable means, including and up to use of deadly force.
2) Saddam Hussein and his crime family had sole ownership of all of the natural resources and imports to Iraq. The sanctions were in effect because he was able to use his power to keep the Iraqi people in his jaws, while they starved. Furthermore, he was in possession of some of the largest oil reserves in the world. He was able to do as he liked with them, and he was the sole profiteer of them. This was, in my opinion, an outrageous offense to anyone who cared about the economic well-being of both the country and the Middle East as a whole.
3) Saddam Hussein only ever called a cabinet meeting when he ordered one half of the cabinet to shoot the other half, sealing them in complicity with his regime. A person could be publicly executed for spilling their coffee on the newspaper that had Saddam's face on it, after which the person's family would be billed for the bullets. People died horrible deaths every day for no other reason than the egotistical glorification of a known psychopath and criminal. Morally, an international community that had any regard for decency could not stand by while this regime behaved like that.
Note: this is **not** an endorsement of the Bush administration. I believe wholly that their execution of the war was abysmal. Their reasons as stated to the American electorate were appallingly cheap and demagogic. They didn't level with us on any of the goings-on in the war while it was happening. They may have even committed a war crime or two. But, that isn't what this question is about.
This question is not about 9/11. My case would have been exactly the same in 1998 (with the exception of Zarqawi, I believe). In fact, it would have been almost complete during the Kuwait War. This question is not about mistakes that were made. It's solely about whether we, as citizens of a global community, were willing to stand by with our guns holstered while our Iraqi brothers and sisters were under the control of the Saddam Hussein regime.
CMV.
**EDIT**: Oh lawd. I've been going at it all day and my brain is fried, but inspired. I just want to say:
1) Some of you guys have had the best arguments I've yet heard against my position. Definitely the best on reddit. I'm gonna keep coming back here, for sure, and not just for my own post. Thank you, sincerely, and keep them coming.
2) Having said that, I feel the need to make something abundantly clear: my contention is not "America has made nothing but good foreign policy decisions ever since the Declaration". It's also not "Bush did the right thing during his execution of the war". It's also not "Bush Sr. was right". It's also not "Bush Sr. was wrong". It's not "X politician made Y statement and that proves me right". I'm very deliberately **making my own case**, separate from any case anybody else made. I'm serious: if I get one more post that starts with "BUT BUSH SAID..." I'm going to go all Bane-backbreaker on my laptop.
3) But seriously, keep it up.
4) <3
5) Also, I'm going to bed right now. It's midnight here in the Philippines and I need sleep. If you leave a response, I'll answer it sometime tomorrow. Scout's honor.
**EDIT 2**: Thanks again for all the incredible insight. I know we're just a bunch of nerds debating politics on reddit, but still. I think I really gained a lot. Particular shout-outs to /u/maxtheman and /u/username_6916, who I've given deltas to for their unique points of view on this issue. This thread appears to be in its death throes, but if anybody wants to keep talking about this, I promise I'll respond if you leave a comment. | Why some atrocities and not others? Why Iraq and not every other problem country in the world?
What do you think made Iraq different or the Iraqi people more deserving of help than the suffering masses in other parts of the world?
If you justify the Iraq invasion on the grounds you've listed, how do you justify *not* acting on the global tragedies that were even more profound, and that are still occurring to this very day? | 18 | 29 |
Where is the line between a bad choice and a bad person? | At what point does a person become the sum of their choices?
First post but I think about this often.
I'm going to provide the following example but after typing it, I realize I'm thinking more towards daily life but please keeping reading:
An extreme example being a person committing one murder. We've all seen stories where a murder could legitimately just be a bad choice (obviously), factors at play lead from one wrong move to another. And then there are serial killers. Quite the difference.
Is the line drawn by intention? What if the single murderer WANTED to murder just like a serial killer, but only did it once.
Is the line drawn by learning from mistakes? Commits murder, oh that was a bad choice, I never need to do that again, doesn't do it again.
What I ponder more on are life choices like choosing a life partner, choosing a job/career path, choosing your friends, choosing when/whether to have a child, choosing a tattoo, choosing to get a pet.
What if a person chooses a burdensome life partner who only causes stress in their life, quits a job they should have stayed at, is surrounded by toxic people, has a child but is not ready to be a parent, gets a terrible tattoo (not so serious but we all know the kind), gets a pet but can't properly care for it, etc. etc.
If that person has great intentions:
I can change the partner to be better.
I will be less stressed at a different job.
These people are good for me to be around. (Idk)
A child will bring me and my partner happiness.
This tattoo is a good idea.
A dog/cat will bring my family joy.
But they end up in an abusive relationship, dead end job, asshole friends, neglected children, terribly tattooed, with a dog/cat they keep locked in a crate all day.
You know what I mean? These are like kind of specific descriptions but are just what I can think of off the top of my head.
At what point can you still say a person is a good person if their life reeks of bad choices?
I understand we all have a built in my metric of good/bad and thus the answer may be only true to our individual perspective.
I also understand factors that affect decision making. (Parents, early life, trauma, accessibility.)
I believe everyone has a purpose, and none are more important than the other. One purpose may be to save the world from poverty, another may be to take frequent naps and only work when needed. Both are equally important to the world. I'd love for napping to be my purpose.
Anyway. I hope this resonates with someone. I'd love some opinions. I'd also love light shed on the biases that are present in this writing. What does it mean that I put so much emphasis on choices? Why do I care about being a "good" person?
Thank you 🙏🏼 | Psychologically, one might draw a distinction between a behaviour that was due to someone's disposition and a behaviour that was due mostly due to circumstances. Clearly, the two interact, but if someone is disposed to be violent, for example, they are more likely to commit acts that others would deem immoral. If that disposition is so entrenched, one might be entitled to call them a 'bad person'.
Interestingly, there some evidence that different people have different intuitions about this. Some tend to see people as having a moral core or moral fibre that is either good or bad. If someone commits a bad act, these people are more likely to judge them as a 'bad person'. This tendency is more prevalent in people who self-describe as conservative, and can help explain things like tough on crime, mandatory sentencing, retributivist rather than rehabilitationist approaches, etc.
Others tend to see actions are being more the product of circumstance and experience. So if someone does a bad act, these people might be more inclined to chalk that up to a rough upbringing, disadvantage, bad luck, including one-off bad choices that lead to circumstances that produce other bad choices (say, a gambling addiction), etc. This is more common among self-described progressives, and can help explain the tendency to focus on systemic problems, rehabilitation and being less retributivist.
Of course, there's a great deal of variation within and between these populations, and there's a recent phenomenon in parts of the progressive left to adopt a more 'moral fibre' perspective. But it's interesting to note that intuitions can vary about what constitutes a 'bad person' and whether they can be rehabilitated. | 38 | 101 |
How can we have 4D objects? | It was my understanding that 2D used an axis on x and y...
then 3D used an axis including a third dimension, Z.
So how do we have 4D? Can we have 4D? | It depends on what you call a dimension and what you call an object. In your example you have X,Y, and Z and you want to add another dimension (let's call it Aa and work from there), while that seems to be impossible to draw we could visualise it.
Imagine you are in a room, this room has three dimensions (X,Y,Z) and a bunch of other variables (heat, pressure, filled with a solid, liquid, or gas, you, light density...), for every point in the room you could determine these variables and draw them (using a computer) in colour. You now have a four dimensional drawing of an object.
Some people call the progression of time a dimension, here if your object changes over time it is a 4D object.
Now for some harder science, quantum physics tells us everything is a wave. And that every wave is orthogonal to every other wave (minor simplifications here, but the example still stands) and that there are infinitely many waves. So you have a wave oscillating in the X axis, one in the Y, one in the Z, one in the Aa, and so on until eternity.
Of course we can't see all these dimensions, but the maths say they exist. And really in science that is all you need. | 15 | 25 |
ELI5: Why is concrete so strong if it is basically just water, sand, and cement that has dried? | At the molecular level, what makes concrete so strong that we can make enormous buildings and support so much weight on it? | Concrete (mostly Calcium Oxide, CaO) doesn't "dry" in the conventional sense: the water doesn't leave, it chemically binds with the CaO and CO2 from the air to form interlocking crystals of Calcium Carbonate. This reaction even happens underwater. | 15 | 21 |
[DnD] Why do they have cemeteries in cities, when they inevitably attract necromancers? And why isn't cremation more popular to prevent this? | Here are a few reasons - communication, closeness, faith and resurrections and security of the grave.
First, not all necromancers are grave robbers seeking to raise up the undead. Necromancers can be an asset to a community. When someone dies, a necromancer gives family a last chance to say goodbye or say things they need to say to them. The necromancer could allow an actual conversation to help both the living and the recently deceased. If a crime were involved, or secrets buried, all that could come out too.
Secondly, people like to bury family close by, maybe even visit. Having a body cremated or carted away in a 'bring out your dead' scenario is pretty permanent.
Third, cremation may also be against the faith of many, since it destroys the body that may be important to their faith. The body may be a vessel for the spirit, or may be resurrected someday. Resurrections are more common than you think.
Finally, a close by cemetary guards the dead from grave robbers, body snatchers and other ghouls. A boothill outside of town is just an invitation to come and rob the graves of body and loot. | 89 | 111 |
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What's in the way of creating a natural-sounding voice that doesn't rely on pre-recorded words? | In other words, when I get directions from a navigation device or the announcer on public transport there's usually either a pre-recorded message (e.g. "examplestreet") or a combination of an established set of words, such as "head" "right" "next" "turn", resulting in a rather jarred sentence.
I realized there's a lot to a voice and humans are great at noticing even the slightest mistakes, but considering how incredibly great we got at rendering facial expressions and the astonishing sound design in various media I couldn't yet figure out what's keeping us from creating such thing.
I also have no clue wether this is the correct flair, sorry. | This is an interesting combination of linguistics and computer science.
One of the biggest issues in synthesizing natural text-to-speech voices is intonation and pitch on specific segments of words. Given a single word, the pattern of sounds' pitches in that word will change depending on the surrounding words and the semantic properties of the sentence. For example, when asking a question: the last word in the sentence will often have a higher pitch than the rest of the sentence.
One would think that these types of things are easily encoded, but you can't just statically encode pitch values for each individual word in the sentence or phrase. It has to be computed dynamically, which leads to a host of other issues. One of the foremost issues there is how computationally expensive it is to determine what part of speech a word is. Others are determining whether something is a statement, question, or exclamation and how the word-final and word-initial phonemes at the edges of words act in concert.
An example of the difficulty in doing that can be found in the phrase, "Hello, it's nice to meet you." Very often, in "meet" (/mit/) and "you" (/ju/), the /t/ and /j/ segments will "merge" into something like a "ch" (/tʃ/). It's not too easy to actually consolidate all of these problems yet, and it's an active field of development, primarily in industry. | 40 | 63 |
ELI5: Why do meats like steak need to "rest" before being consumed? I've never done this and I've always enjoyed my food. Am I missing out on something extraordinary? | So when you cook meat like steak or chicken breast you are putting a lot of different forces (or stress) on the meat. Letting it rest for a few minutes gives the cut of meat time to allow the juices time to reabsorb into the muscle fibers, allowing for a juicer cut of meat. You'll notice when you let it rest that there is less juice on the plate which means it's all inside the meat. | 36 | 23 |
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ELI5: why do some vaccines confer life long immunity while others just a few years? | Vaccines work by presenting an inactive version/element of a disease causing agent (antigen) to the patients immune system, allowing their immune system to develop antibodies against said antigen. This is analogous to police posting wanted posters of a criminal's face around a town the criminal is likely to hit. The people in the town will know what he looks like and will be able to respond appropriately if they see him.
Microbes, however, will evolve over time at different rates (the flu virus evolves quickly as it passes quickly from host to host but other viruses, such as HIV, evolve more slowly). Sometimes microbes will evolve so much that the antibodies in a person's body can no longer accurately detect and fend off their assault. This is like the criminal in the above example receiving some type of cosmetic surgery to change his appearance. Now the townsfolk won't recognize him and he'll be free to steal their women and rape their cattle. | 14 | 18 |
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In the context of quantum physics, what does 'symmetry' mean? | It means the same thing it does in classical physics. It means that your physical system looks the same when you perform some operation on it.
For example, on a large scale, the universe looks exactly the same no matter where you're located. That's symmetry under spatial translations.
The universe also looks the same no matter what direction you look in. That's symmetry under spatial rotations.
There are more abstract symmetries as well, like the fact that the physical state of a quantum-mechanical particle doesn't change if you multiply its entire wavefunction by a complex phase. | 34 | 47 |
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Why is the East coast of the U.S. (Maryland to be specific) so much more humid than the West Coast (such as California). If they are both near the ocean, shouldn't both be equally humid? | Title | The ocean currents flow north from the equator in the east, resulting in warmer water, more cloud formation, higher rainfall, and greater moisture content of the air. In the west, the ocean current flows south from Alaska, resulting in colder water, less evaporation and cloud formation, lower rainfall, and less moisture content of the air.
Same is true in south America. The east coast (Brazil, Argentina) is very humid while the west coast (Chile, Peru) is very dry. | 436 | 738 |
ELI5:Why do natural gas plants have a burning smokestack? Or flare stack? | I think I get why they do it. Its a safety issue. But why cant they extract the gas and use it for energy? It has to be incredibly wasteful, both economically and as far as conservation goes. | Natural Gas plants work by purifying "sour" gas (high H2S) from the ground into "sweet" (low H2S) gas. H2S is the main pollutant from the process, although a few other trace gases may be present. The requirements for sweet gas are around 4 parts H2S per million parts gas. Very little of the major components of natural gas (methane and ethane) are removed with the H2S. The little bit that is unavoidably removed with the H2S is, as you said, used for energy elsewhere in the plant, namely in the sulfur making process described below.
The H2S that is removed is usually sent to a different process to make sulfur to be sold as a byproduct. This process requires multiple reactors, catalysts, piping, etc to work. Each reactor can only achieve about 70% conversion of H2S to sulfur. Thus a high recovery requires multiple reactors. Even afterwards, however, there is still some H2S remaining. EPA requires that H2S emissions be no higher than 5 parts per billion or so.
At some point, it becomes more cost effective to just burn off the little bit of H2S to make SO2(which is less environmentally hazardous, although still strictly regulated) and H2O, rather than building another reactor sequence in order to extract what is an increasingly deminishing return of sulfur. Basically, the flare stack is used when the cost of installing another reactor would be greater than the additional added value that that reactor would produce over the lifespan of the plant.
Edit: The sulfur making process requires high temperatures. To create it, H2S is reacted with SO2. To make the SO2, a little bit of H2S must be combusted at the high temperature, and then the reaction can proceed. This is where the little bit of methane and ethane can help, because they can be combusted at the same time to create the high temperatures needed for the reaction. | 12 | 17 |
Could gravity waves theoretically be reflected or refracted? | Also, just as light waves [impart a force](https://en.wikipedia.org/wiki/Solar_sail) to things they interact with, would it be possible to cause net motion with gravity waves? | Gravitational waves can be "refracted" by massive objects in the same sense that gravitational lensing is a form of refraction.
Gravitational waves do cause objects in their path (including you and me) to move a tiny amount. That is in fact how they are detected. | 13 | 25 |
ELI5: Why are video cameras used for television production so much larger than consumer based ones? | Whenever I see behind the scenes footage of a reality TV show the cameras they use are quite large shoulder mounted beasts. Whereas, the video camera I have is handheld and produces HD video exceptionally well. What extra "stuff" is inside these huge cameras and how does that make them superior? | Bigger lenses and sensors. The focusing system is a lot more precise than a home model, they have better image stabilization, it also takes up more room with bigger motors and that kind of thing. This is going to be the biggest difference in size. They want the best image quality so they build it with a lot more processing capability. Instead of one chip doing three things, they have 3 chips doing 3 things very well. You might not notice the image quality difference between a professional broadcast and your camera if you aren't looking for it, but you are watching a compressed, scaled down version of the video they really record when watching at home, you would notice a difference side by side for sure if they decided to broadcast your video. Storage is important so the cameras have flash memory and sometimes conventional hard drives, and they are both a lot bigger than an SD card. Some still take digital tapes too. And you want a button for important things like white balance, exposure, iso, fstop, focusing, no going through a menu for that sort of thing. They have much better preview screens. High resolution, high contrast, very bright. Also, those cameras have wireless mic capability and even wireless transmission capability to a news van, for example. And the batteries to power all of this stuff need to be a lot bigger than a DSLR to get comparable life from them. That is the step you take from a decent clamshell to a professional. | 38 | 42 |
[HARRY POTTER] Becoming a powerful wizard. Are you born with it or can you learn to be one? | Simple question. Can you learn to be a great wizard by pure hard work and skill or is it something that you are born with.
Most of the powerful wizards display superior magical prowess at a young age without any training. Take Voldy's magic while he was at an orphanage as an example.
Is it something that you could simply work at it and become a powerful wizard?
(Pre-empting that people will cite Hermione as an example. She was a hard working witch but I doubt she could become as powerful as Voldemort even if she had the ambition to) | Natural aptitude certainly has something to do with it. If you aren't prodigiously gifted, you'll never be a wizard the like of Dumbledore or Tom Riddle. That said, any wizard of that caliber has devoted a lifetime of study with an erudite mind to the craft in addition to their inborn talents. If you are a wizard of average aptitude, you can still become great. Take Kingsley, McGonogal, or Snape. They are all extremely proficient wizards, and none of them are magical prodigies. Their greatness comes from self cultivation. | 86 | 103 |
ELI5: If World War II era guns were so good, why did we replace them? What advancements have modern firearms made that warrants replacing standard issue weapons? | After WWII there was a pretty strong effort to look at how small unit engagements had happened and to figure out better weapons and so on from that information. Two big things that became apparent was that it was very rare for small arms to matter much beyond around 300 yards, and that the big factor in small unit success was the ability to throw a lot of lead at the enemy quickly.
With these lessons in mind the decision was made to go from "full power" rifle rounds like the 30.06 to "intermediate" rounds like 5.56. The 5.56 round that the M16 fires is not nearly as powerful as the 30.06 that the WWII era Garand fired, but the M16 had 30 rounds of ammo in a mag vs. the M1's 8. Less power also means less recoil and so the soldier with the M16 can fire faster without the recoil dicking up his shots. The M16's bullets also fly faster and flatter, so the modern soldier is much more likely to make an effective "snap shot" than his WWII era counterpart.
You also have various ergonomic improvements, a chrome lined bore, easier manufacturing, all NATO rifles were set up to use the same ammo and magazines so if you were next to a German unit you could borrow their shit if you needed it. | 175 | 147 |
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[Doctor Who] When the Cybermen's emotional inhibitors are disabled, the humans inside collapse in horror at what they've become. What would happen if one such human thought becoming a badass cyborg were pretty frickin' sweet? | I believe there are a few examples of people being committed enough to duty and honor that they were able to take constructive action post-conversion and post-inhibitor failure. Though it was less "yay, dope metal body" and more fighting through the pain and terror on raw gumption.
You see, the act of becoming a Cyberman is profoundly traumatic; a live, typically conscious human is quite brutally disassembled and then rebuilt into a mind-controlled monster. When the inhibitor goes off, they deal with all of that trauma, plus whatever horrid stuff they were made to do while a Cyberman, plus the horrid body dysphoria of having a human brain in a cyborg frame.
For someone to experience all that and go "woot", they would have to be quite seriously disturbed. So, such a person would likely be a villain in the making. A heavily armed and armored nutcase, a walking tank with a defective pilot. Depending on how canny they are, they could either wind up an impossibly brutal spree killer or an ever- present specter over human civilization. | 41 | 47 |
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ELI5: How exactly does a preservative preserve food and what exactly is a preservative? | Echoing what the others say, it's all about "available water".
Salt and sugar does the same thing - draw water away, or make the water too salty/sugary for bacteria to live in it.
Things that change the acidity kind of does the same thing - they make the water inhospitable, so the bacteria can't live in it.
You can also make a mix of the two, using a bit of vinegar and a bit of sugar.
Drying something also takes away the water.
* This is what is done with jellies and jam and fruit preserve and a lot of other things - olives too.
The only thing that's different from all of these only works on things that are sterile - you can cover the outside in something that's toxic.
The toxic thing can be a mold, strangely enough - because the mold makes toxins to protect itself, so other bacteria and molds can't survive. But it means you have to cut the outside away when you want to use it, and then you can't leave it, because you've opened a door for bacteria and different molds to "enter".
* Camembert is like this - the outer layer is a living mold that kills everything else.
The toxic thing can also be residue from smoke because the thin outer layer is toxic, the bacteria can't enter. We can take a big bite of it, though, because the layer is very thin, so there's not enough toxin to affect us.
* bacon and fish are often preserved like this | 2,332 | 7,431 |
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Why is the N-Body problem considered un-solveable in the general case? | Can you not just do a step-wise integration to come to a correct simulation of an n-body system? | A few considerations, in lieu of a full answer:
Step-wise numerical integration isn't really considered a full solution, generally that's reserved for some sort of closed form expression or series. There is a solution to the N-body problem, but in practice it's even slower than the numerical solution.
The problem with numerical integration is chaos: eventually there are situations where the exponential dependence on initial conditions means that no matter how small your time-step is, eventually the system could evolve in a totally different way depending on your numerical scheme. | 26 | 18 |
Do I need to know any programming basics in order to go to college? | I have just started learning Python and thought that it might be a very good idea if I went to college next year (I'm in 12th grade now) and study programming. But I have some questions: Do I need to know programming basics in order to pass the admission exam for college? Or do universities not require you passing any admission exam and you just start to learn about programming in college?
I know it depends on the university, but I would like to go to one that will offer me a good education and will enable me to find a job as a programmer after graduation. I don't want to spend 3 or 4 years in college just to learn how to say "Hello World" and then to work for Mc Donald's.
I would be very grateful for productive answers. | No, you don't need to know programming basics in order to go to college or to major in computer science when you get there. I've never heard of colleges having a programming exam for admissions, but you can check with the colleges you would be interested in attending. However, it definitely helps to learn as much as you can on your own before you go. Most importantly you can verify that it's something you're really interested in further pursuing. Then of course there's the added benefits of learning to teach yourself (an essential skill in CS imo) and giving you a solid background that will put you ahead. | 30 | 36 |
ELI5: How can wine tasters claim that a particular wine has a taste of exotic fruits, vanilla and other things that are not actually present inside the wine? | Whenever I read the description of a bottle of wine, there is always a lengthy text explaining the taste and texture of the wine. Most expert wine tasters tell you that a wine tastes like a mix of exotic fruits or has a special scent or taste.
But when I drink the wine, it just tastes like grapes and alcohol. Am I missing something? | Certain winemaking techniques impart flavors similar to things like vanilla, grapefruit, "earthy" etc so they're just used as a frame of reference to describe the taste.
For instance, wines aged in oak barrels often have a hint of vanilla-like flavor. Low-sugar wines made from the Riesling grape varietal frequently have light peach or apple like taste.
This is simply a result of how that specific grape taste when nearly all of the sugar in it is converted into alcohol, so the more subtle latent flavors are easier to detect. If you ate that same grape off the vine it would just taste like a grape.
Additionally, there are certain descriptors used to describe the alcohol quantity of the wine. A "big" red (for instance a Cabernet Sauvignon at 13.5% ABV) will "bite" as the alcohol reacts with the surfaces in your mouth. A smoother wine will, well, go down smoother, and this could be the result of less alcohol or flavors that mask it.
Last and not least is the tannic content, and this is kinda similar for our purposes here to the alcohol content, and oftentimes they correlate. Tannins are found in the skin of grapes (so white wines, where the grapeskin isn't included, have little to no tannins) and contribute to the mouthfeel and the bitterness much in the same why that the alcohol content does (it is different but don't worry about that for now). It's a similar compound in grapes as what you would find in tea or coffee. You might hear a very tannic wine described with words like currants, blackberries, earthy, or any number of similar flavors. | 20 | 25 |
ELI5: How do GPS apps such as Maps or Waze know the new formation of roads after construction? | It first important to understand how Google Maps gets all if it's data. Some of it's data is pre-programmed into their systems. This is usually used as initial data, especially for testing. Google provides many more features, however. They also show traffic and other information for your daily traveler.
A few years back, Google acquired Waze and they use data from the Waze app to enhance Google maps. Waze is backed by a community of users who report cops, traffic, accidents, etc. But Google also injects tracking into their software. Google can access the speed of your car by checking it's locations at two different points and dividing it by the time between those two points. If the speed limit on a road is 50 mph, but every car on the road using Google maps is moving only 10 mph, then there is obviously traffic.
Using the same technique Google will track a cars movement. If a car is going off course, then Google will ignore the data, but still store it for later use. If 50 cars go off course, Google's map algorithm will detect this as an unknown road. Google will run several Artificial intelligence tasks to determine what is going on and will adjust their data accordingly. | 40 | 39 |
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How come if I put Rain-X on my windshield the rain/snow beads off but on cold mornings it's able to have frost stick to it? | Rain-X is effective on water in its liquid state because it is a hydrophobic surface treatment. It causes water to bead up and roll off. It is not as effective against snow because frozen water is hanging on by friction instead of surface tension, and won't bead up until it melts. | 23 | 55 |
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CMV: Many people don't evaluate 'capitalism' properly. It's a great economical system. | Capitalism's brand name has suffered tremendously over the past two decades.
However, most people do not understand the basic facts about it - in the past 500 years, where capitalism ruled the economical system, the human race went through the its most advanced phase of its development, in all fronts.
Capitalism is probably the best rewarding system there is to get people cooperate together, to create the best environment for them to live in.
It's not perfect, many people are falling short for that on one side of the spectrum, others are taking advantage of it on the other side of the spectrum, but although it demands constant tweaks and adjustments - it's the best system out there.
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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!* | To start off, it would probably really help if you clarified terms. What do you define capitalism as? Any system where there is a market economy and private ownership? A specific level of lassies-faire involvement? So many discussions of "capitalism" never get anywhere because everyone involved has a completely different idea of what capitalism is. | 34 | 44 |
Is there any difference between mass granted by the Higg's mechanism versus mass granted by the Strong force? | Forgive my terminology, but as I understand it, the Higg's field creates mass for elementary particles, but the vast majority of mass we see is a result of the strong force holding together bundles of quarks and nucleons. How is it that these 2 seemingly different mechanisms result in something that on our scale look like exactly the same thing? Does mass created by the strong force interact with the Higg's field? Does mass created by the Higg's field interact with the curvature of spacetime? | > Is there any difference between mass granted by the Higg's mechanism versus mass granted by the Strong force?
No, there is no difference.
> How is it that these 2 seemingly different mechanisms result in something that on our scale look like exactly the same thing?
Because both mechanisms are doing the same thing: confining energy. The strong force confines the energy of particles with color charge into a small amount of space, and the Higgs mechanism confines the energy of particles that interact with the Higgs into a small amount of space. In both cases, mass essentially results from the relation E=mc^2 , by virtue of the respective forces confining energetic particles and thus giving them some average rest frame.
An advanced undergraduate-level exercise, which might help, is to show that a photon trapped in a massless mirror-box has an effective mass given by E=mc^2 . It doesn't matter what forces hold the mirror-box together; what matters is that energy is confined.
| 15 | 25 |
ELI5: Are reflective objects reflective in all spectrums of electromagnetic waves? also, how do objects "reflect" heat when heat is something else entirely? | Nope. Nor are they transparent across the whole spectrum.
For instance, many optics used in infrared research have lenses made out of germanium. It's not transparent to us in the visible spectrum but it is transparent in the infrared. Another example is x rays, which are a much higher frequency electromagnetic radiation than visible light. Your skin and flesh are transparent to x rays but your bones are not, so you can use them to look at your bones. There is even a part of the spectrum, mid infrared, where air is not transparent. So every physicist who works in the mid infrared has a hard time doing his experiments because he has to get rid of all the air in order to see anything. | 11 | 20 |
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ELI5: Movie Credits | "Producer" is a title that has a huge number of responsibilities, from securing financing to finding source material to casting to managing post-production to dealing with marketing and distribution. If the director is the one responsible for creating the product, the producer is the one ensuring that the product gets made and seen at all.
Large productions will have a lot more problems that need solving than smaller ones, so as the scope grows, the responsibilities of the producer also grow. So the executive producer will manage a team of other producers, each with their own tasks to perform. Here is a summary, courtesy of How Stuff Works:
Associate Producer -- Handles certain aspects of production, as assigned by the producer. Usually the associate producer has worked through all three stages of the production, from preproduction to post-production. Sometimes the associate producer title is given as a courtesy title to a key backer of the film who does not have a major role in producing the film.
Assistant Producer -- Works on tasks assigned by the associate producer.
Co-Producer -- Shares producer responsibilities as a team or group with other producers. One producer may take on creative responsibilities while another handles business functions. Or one of the producers may be a major investor who is not directly involved in the movie production. Or a co-producer may have brought the script or the film's star to the production.
Supervising Producer -- Oversees one or more producers as they perform some or all of their duties. The supervising producer may take the place of an executive producer or work for the executive producer.
Coordinating Producer -- Coordinates the work of several producers to create a unified end result. Coordinating producers are valuable when a studio produces several related films, as with "Spiderman," or particularly when two related films are being produced at the same time, as with the two sequels to "The Pirates of the Caribbean."
Line Producer -- Handles the physical aspects of a movie's production and usually is not involved in decision-making regarding creative issues. This is the person who oversees the budget and day-to-day activities during filming. In addition to making sure the movie stays on budget and on target, the line producer handles any crises that may occur. | 46 | 71 |
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Is it necessary to read Kant before reading Schopenhauer? | I've recently started reading World as Will and Representation. The foreword from the author explicitly gives you a "manual" on how to read this book. Apart from instructing the reader to read some of Schopenhauer's earlier essays (e. g. On the Fourfold Root of Principle of Sufficient Reason) Schopenhauer also stressed the fact that the reader should be familiar with Kant's principal works.
Is it really necessary to thoroughly read Kant before diving into Schopenhauer or will just general knowledge of Kant's thought suffice and allow me to understand Schopenhauer's works? | A general knowledge of Kant suffices because Schopenhauer explains Kant pretty well through paraphrase. However, his philosophy does explicitly build upon Kantian foundations, and contemporary readers of Schopenhauer would have been familiar with Kant by default.
You will very quickly be able to tell for yourself, as you go through the first book, whether or not you need to read some (more) Kant before going further. | 24 | 21 |
AskScience AMA Series: We're here to answer your questions on living with the invisible symptoms of Multiple Sclerosis (MS), AUA! | Multiple sclerosis is a complex disease that affects the central nervous system, including the brain, spinal cord, and optic nerve. Many of its symptoms are easily noticed, like gait, balance, tremor, and speech. But others are not visible to the naked eye - like fatigue, cognitive dysfunction, and pain - and make day-to-day life with the disease difficult to navigate for the more than two million people living with MS globally. Today from 11a - 2p ET (16-19 UT), Patricia Coyle, MD and Patricia Melville, RN join us to take your questions about the invisible symptoms and disease related to MS.
[MS Team Meeting: The Impact of the Invisible Symptoms of MS](https://www.psychiatrist.com/ms-team-meeting-the-impact-of-the-invisible-symptoms-of-ms/) is a new four-part video series featuring Coyle and Melville for [The Journal of Clinical Psychiatry](https://www.psychiatrist.com/). Watch as they share an in-depth conversation with Lillian, a woman with MS for the past 30 years who shares a candid account of life with this disease.
Patricia K. Coyle, MD is the director of the MS Comprehensive Care Center and professor of neurology at Stony Brook Neurosciences Institute.
Patricia Melville, RN, NP-C, CCRC, MSCN is a supporting specialist at Stony Brook Neurosciences Institute.
Learn more about multiple sclerosis in the [MS Clinical Resource Center](https://www.psychiatrist.com/topics/neurologic/multiple-sclerosis/).
PROOF: https://i.redd.it/1bgctzp8yt281.jpg
Username: /u/PsychiatristCNS | Are there mild forms of MS where someone could be mildly affected but go undiagnosed for their whole life?
And are there times when one or two symptoms appear, but most of the common symptoms are absent? | 96 | 1,521 |
[WALL-E] Sentience of Wall-E vs. Axiom robots | Were the robots on the Axiom designed to be sentient upon the ship's original launch?
We know that Wall-E developed sentience over the course of 700 years simply due to life experience, but what about the robots on the Axiom? Was the technology available at the time of launch for the robots to be sentient? Were they designed that way? Was AutoPilot actually a sentient computer or just a [Strong AI](http://en.wikipedia.org/wiki/Chinese_room#Strong_AI)?
If they weren't originally intended to be this way, did the technology for sentient robots develop slowly (via human innovation) just like Wall-E's naturally-developing consciousness, along the same timeline? | The Axioms robots were designed with sentience for user friendliness and more complex decision making (Auto).
Wall-E units were mass produced and designed for one purpose, therefore sentience seemed unnecessary. | 11 | 27 |
ELI5: What's the difference between a "balanced" and "unbalanced" XLR cable? | Or just what are balanced and unbalanced as it relates to Audio in general?
Also, can anyone tell me what would be best for recording audio on a film/video production set? | A balanced line consists of two conductors and a shield, while an unbalanced line is one conductor with the shield serving as the second conductor. Balanced lines are preferred in audio because they're less susceptible to electrical noise.
XLR and TRS cables are balanced. RCA isn't. TRS connectors are tip, ring, sleeve. They're 1/8" and 1/4" jacks with an extra ring near the tip. For example, a guitar cable is an unbalanced 1/4" jack, but 1/4" headphones are TRS.
Source: Broadcasting major with an emphasis on audio | 10 | 27 |
ELI5: how come I feel confident about finishing my schoolwork and getting a passing grade when I'm doing something else (working, taking a walk or a shower), but when I actually sit down at my laptop, I get overwhelmed by my lack of motivation, pressure to succeed and fear to fail? | EDIT: Well, sheeeeeeit. I did *not* expect this to get as much attention as it's getting. Consider [this](http://i.imgur.com/l3zaUKx) me right now. Thank you all so much for your upvotes and your kind, insightful and helpful replies. I'll read all of them. Now I'm swamped with school work *and* reading all these comments! | Another important strategy to adopt in school is this: When you get an assignment, as soon as you are humanly able to, do as much as you possibly can to finish the assignment in 5 minutes.
Just 5 minutes. Each and every assignment you get, spend 5 minutes and really try to produce the best result possible given that short amount of time. The point is to identify all the parts of what's required and at least touch on each part before the 5 minutes is up, in other words, don't spend the entire 5 minutes working only on the first bit–your goal is to produce the best possible thing you can hand in in just that 5 minutes.
Of course, whatever you produce won't be any good. But it will get you thinking about the details of whatever the required work is, and it will help you step through the entire thing in your mind to completion and identify all the possible pitfalls. Instead of being this nebulous 20 page paper due in a month, it's now an outline ... or at least an outline of the activities you need to do to figure out what you're going to write about.
This will prepare you the very next day to go back to your teacher and ask any questions that came up during that 5 minutes...these are the things your classmates will run into the night before it's due, and won't have the opportunity to ask anyone anything.
With a problem set in math, it will give you a quick answer to how many questions you have to answer and what topics are covered in that problem set. Which ones look easy and you already know exactly how to do them, and which ones are you a bit foggy on, and which ones do you not even understand what's being asked for?
If you're anything like me (or most people), the moment your 5 minute timer goes off, you will start right to work on knocking down all the easy stuff you identified, and maybe you can knock off a couple of the middle difficulty problems. This leaves only the real meat of the assignment and helps you understand exactly what that is so you can start working on how to attack it.
One other thing about this, you'll notice after you do this every single day for a few months, you get really, really good at scoping your homework, and you get really good at identifying things in the assignments you are not good at and getting the answers you need before it is too embarrassing to ask.
(Once a teacher told us we had to write a 20 pager in high school, but nowhere on the assignment did she list double spaced or single, margin requirements, etc...it was all verbal, and only mentioned once in class. Many kids had to ask her what the page requirement was, and more than half the class asked her the day or two before it was due. Oops. Yes, she did that intentionally.) | 755 | 1,333 |
Can someone explain how exactly dd Gaston Bachelard in the words of Balibar "tear epistemology from the undefined commentary of ('inductive') relations between 'theory' and 'the facts'" and thus solve the problem of induction? | I came across this problem while reading: Etienne Balibar (1978) From Bachelard to Althusser: the concept of ‘epistemological break’, Economy and Society, 7:3, 207-237, DOI: 10.1080/03085147800000013 ([https://doi.org/10.1080/03085147800000013](https://doi.org/10.1080/03085147800000013)) in which Balibar in a note to the paper writes:
>One aspect of Bachelardian epistemology which has had important consequences will be held to be central. It is the thesis according to which *the* *concept* is the *unit* par excellepce typical of scientific knowledge because it is also the singular unity of (mathematical) theory and experimental technology: '...to incorporate the conditions of application of a concept in the very meaning of the concept' (Bachelard 1938 p. **3** 1) not in an arbitrary *isolation* of concepts but in their interrelation, their 'interdefinition'. (Cf. Bachelard 1949 pp. 51f, 144f) By this means Bachelard tears epistemology from the undefined commentary of ('inductive') relations between 'theory' and 'the facts' in order to propose for it the study of historical relations between constitution (and then transformation) of concepts and posing of problems.
Thus, is Balibar saying that Bachelard solved the problem of induction as identified by Hume? If so, can someone explain how did Bachelard achieve this feat? | Not a Bachelard scholar, but recently become acquainted with his works; basically he states (anybody knowing more please feel free to correct me), that there is no arbitrary position because the way you think and approach concepts are defined by how you imagine them beforehand - he states imagination is the basis of thinking.
He has what's described as a poetic approach to philosophy and science - I'd advise you to read or get a summary of Psychoanalysis of Fire; or Water and Dreams to get a clearer view on that. | 12 | 45 |
ELI5: Why does inflation even occur? Can't we just "reset"/"deflate" the value of money? | Edit: Sorry I realised I should have phrased my question better.
Correct ELI5: Why can't we just reset/deflate the value of money when inflation occurs to prevent prices from becoming exorbitantly high over a long period of time resulting in everyone having to pay for simple items using colossal amounts of cash?
^Which I now understand is unfeasible and impractical, at least for now. Thanks for all your answers! :) | A small amount of inflation is pretty hard to avoid in a growing economy - you need more money circulating so that everyone has money to spend, rising wages means sellers can charge more for their goods, etc. And it's not a bad thing - it encourages people with lots of money to spend or invest it, as it is slowly losing value sitting in a bank, which frees up capital for further growing the economy.
You can deflate or reset a currency but both have problems.
Deflation has the opposite effects - people hoard money (it'll be worth more if you spend it tomorrow), which means less new business and existing businesses selling less, which leads to cutting employees, etc. which can spiral down into nastiness quickly.
Resetting currency is really worse. It's hugely complicated and expensive, and it has a tendency to make other people very skeptical of your currency. Lots of unstable countries with high inflation have done things like say, "Ok, as of today every 100 old dollars now equal one #Strong Dollar" - that doesn't actually change anything, except make businesses move the decimal point on price tags, but it does tell the world "Our currency is really fucked and we can't fix it", so no one wants to do business with your currency that might suddenly get devalued again. | 43 | 46 |
ELI5: Why are the ceilings in so many grocery stores so high? | Doesn't this increase both initial building costs and subsequent heating costs?
Edit: Thank you to everyone who helped to answer my question. I had no idea so many factors were involved. | It makes the store feel open and less crowded, and it lets you set up displays that take advantage of the height, such as signs visible anywhere in the store. It also makes moving things with machinery like forklifts easier.
Psychological experiments have shown that people don't like being in areas with low ceilings. Some airports have made use of low ceilings in places where they don't want people to linger, like the front of the check in line.
edit: check in, not check out. | 1,295 | 1,127 |
Why is there a graph for √-x if you cannot square root a negative number? | Consider the input values here. We're looking at sqrt(-x) for *negative* inputs. So for x = -1, sqrt(-x) = 1.
When we graph sqrt(x) in some program like desmos we only see one branch of the graph, the branch of real outputs. For your graph, you're seeing the "real branch" of values for f(x) = sqrt(-x). | 47 | 37 |
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[40K] Which of the Chaos Gods best rewards their followers? | Let's face facts for a minute - humanity is screwed. We've been fighting the powers of Chaos for millennia and not once have we had any real success. They gain power from the very nature of humanity and all we've got on our side is a withered old corpse and a bunch of 'roided up boy scouts.
Now before you get all "die heretic" on me, stop and think. Wouldn't it be nice to be on the winning side for once? You've got to think long term. Humanity might hold on for a little while longer, but Chaos is eternal.
I've been considering my options, but given that I'm looking at the long term, which Chaos God best rewards their faithful servants in the "afterlife"? Sure it'd be nice to have power and glory now, but I can delay gratification for a greater eternal reward. | It depends largely upon what your ambitions are.
Many consider Papa Nurgle to be the "best" to his supplicants because he is the only Chaos God that appears to TRULY care about each and every single one of them (at least in his own way). The others tend to simply see each new convert as a means to some unknowable end.
That being said, the rewards for pleasing a Chaos God - any Chaos God - can be incredible.
Khorne can bestow upon you the strength to utterly crush your enemies. Khorne can imbue in you the kind of thoughtless brutality that makes even Him blush. You will be a vaguely biological machine of eternal war, bringing forth a sea of destruction that washes over everyone and everything in your path.
Tzeench can show you the intricate paths of fate, and bestow upon you knowledge of things even the most ancient beings have long since forgot. He will give you access to Psychic powers that make Librarians seem like disabled children. He will weave you into His great tapestry and guide you to greatness.
Slaanesh will allow you to experience sensations and emotions you could never have thought possible. She will bestow upon you the means to inflict any pain, any pleasure, or any emotion upon those lesser than you. You will be made a maestro of screams, both pleasurable and agonizing, and you will compose a symphony worthy of the Lord of Excess.
Nurgle will show you what life truly is, and what it is truly capable of. You will be shown its infinite diversity, its all-reaching influence, and its innumerable weaknesses. You will be given access to His Garden, and the means to paint an ever-expanding mural of pestilence and corruption, ensuring that all have the chance to share in the love of their Papa. You will be capable of both taking and *giving* life, like the force of nature that you are.
The gifts of the Gods are as great as they are terrible, but they come at the cost of your soul. You are now property, owned by a being that cares little for the future of anyone but themselves. As much as Grand-Pappy Nurgle loves you, His true love is within His Garden. As much as Khorne wants to see you lay waste to all before you, He only truly cares about His skulls and His blood. As much as Slaanesh wants you to explore the vastness of sensation, She really just wants to fatten you up to consume your soul. As much as Tzeench might love to see the fruits of your sorcery, manipulations and strategies, in the end, you are merely a pawn in His infinitely complex scheme.
Your ambition is the only thing that will get you anywhere in this galaxy, and with the favor of a God of Chaos that ambition can be taken to heights not seen since the rise of the Anathema. Your soul can either belong to a corpse, or it can belong to beings that have existed since the infancy of our race, beings that brought a God of Order to His knees before His own son.
Eternity is a long time. How do you want to spend it? | 74 | 53 |
ELI5: What is the world bank, how was it founded, and what authority does it wield internationally? | The World Bank was founded after WWII, as part of a larger reshaping of the global economy under US leadership.
As its name suggests, it is a bank. Like all banks, it is in the business of lending money. But unlike a normal bank, which lends money to people and companies, the World Bank (and the International Monetary Fund\*) lends money to countries.
Sometimes these loans are for specific projects that a country needs to finance. Sometimes they're emergency bailouts to countries that are having financial issues. In recent years, the World Bank and IMF have concentrated on loans to developing countries to reduce poverty.
&#x200B;
> **what authority does it wield internationally?**
The same as any other bank. It doesn't have a direct way to force countries to pay back loans, it relies on its members to exert pressure individually
&#x200B;
\**The World Bank and IMF are sister institutions that do the same job. The difference is that the World Bank is traditionally led by an American and the IMF by a European.* | 13 | 21 |
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ELI5: Every part of this sentence "I run mergers and acquisitions for a large private equity hedge fund" | Edit: What I mean is what is a hedge fund, what makes it private, what does it mean to run mergers and acquisitions and what does that person do in a private equity hedge fund? | I = Narrative individual
run = manage/head/oversee
mergers and acquisitions = combining, selling or dividing up bits and pieces of different companies
large = big
private equity = strategy of making large investments into a few specific private companies (not listed on the public exchange)
hedge fund = strategy of managed, flexible portfolios of investments, usually much broader than private equity in range to reduce risk
The sentence doesn't quite make sense though because "private equity" and "hedge fund" are two different strategies. | 67 | 95 |
If the immune system "learns" and "remembers" viruses, how and where is this information created and stored? | My understanding of vaccines is that we take "dead" viruses, and inject them into the body so that our immune systems can learn to fight them before we first get them. My guess is that somehow the white blood cells (?) adapt to the virus somehow, but in what way? Do they unzip parts of DNA like cells do when they replicate? What would they even do with these pieces of DNA or whatever information they learn? ie. how does that information help them kill the virus? Do they then go and hide out until later waiting for the next infection?
| To simplify greatly, there are immature immune cells present in your body. Certain types have "hypervariable" regions which, for complex reasons, are able to develop with incredible diversity on a molecular level. Enough diversity that virtually any complex protein (which are absolutely essential for life but are incredibly complex and based upon certain patterns) can be matched to a hypervariable region of some small subset of immature immune cells.
When a certain antigen (epitope technically, but antigen is a word most people know) is widely present in your body (like during an infection), this induces the clonal proliferation of immune cells which have hypervariable regions which are able to respond to that antigen. This proliferation has a far greater degree of mutation than normal cell division, which ensures that new cells which are best able to respond to the antigen are selected for. The cells with the best response to the antigen thus reproduce the most.
Most of the cells produced to combat a given antigen die off quickly if the antigen is no longer present. However, a select few remain which do not directly combat infection, but retain the affinity for that antigen. They stick around, and if that antigen is encountered again, they quickly begin clonal proliferation, ensuring a full blown infection will not occur. | 21 | 36 |
ELI5: The differences between a nation, a state, and a nation-state. | As many times as I've had this explained, it never sticks. I'm unashamed to ask for a simple explanation. Knowledge is power!
Thank you. | A nation is a group of people with several factors in common like land inhabited, religion, ethnicity, language, or culture.
A state is the government over an area of land
A nation-state is a state that governs an area that primarily consists of one nation. | 42 | 83 |
ELI5: Why do some foods quickly become overwhelming? Like a quadruple chocolate cake or foods that taste very "rich". | Rich foods tend to have a lot of free fat and other things that coat the tongue (like chocolate). This can create an overwhelming feeling in the mouth because you're *constantly* tasting chocolate and can't access other tastes. Adding some other taste - especially something acidic - can help to refresh the mouth. This is why cream cheese (mildly acidic) frosting is so popular. Also why the secondary flavor of a dessert is often something citrusy like lemon or orange. | 29 | 16 |
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I believe states' rights are an issue of absolutely no importance and should matter to no one. CMV. | I could honestly not give one crap about states' rights and I don't understand why anyone does either. This has nothing to do with the Civil War ("states rights" was not the reason the South seceded and was only invented as a justification after the fact). It's just that, I don't see the big deal. Governments overrunning the rights of the people, that matters. But federal government overriding the state government? I've never heard a compelling argument that includes those words, whether it supported views I liked (drug legalization) or didn't (overturning Obamacare). I can see why, with separation of powers, we wouldn't want the executive branches overriding one of the others ones outside of its defined authority, or vice versa. But if a federal law overrides a state law, I don't see why it matters. | Having several different states with enough rights to determine a majority of their laws gives citizens of the US 50 different sets of laws in which they could follow. A greater amount of choice lets people live in better conditions than they otherwise would. It also gives 50 different testing grounds for new ideas. For example if there was a law that would take all taxes away from a state except for sales tax it could be implemented and tested in one state first, then another and another. Then it would succeed. Or the law would start in that one state fail miserably and show better real world reasons why the law wouldn't work. | 31 | 30 |
Cutting my PhD thesis in half | I can't avoid the fact that the last two thirds of my Computer Science PhD thesis is much stronger than my first third.
The first two years of my studies were devoted to following dead end routes and discussing these dead ends forms about 25,000 words of a 75,000 word thesis. In that section there's a lot of explanation that's mostly in service of exposition for the final part, with no real satisfying outcomes.
I have a feeling that in my viva I'm going to be defending those 25,000 words non-stop and I really don't want to do that. Instead I was thinking that I might be able to get away with just not mentioning my early work. All I have to do is re-frame the latter half of the work.
I haven't spoken to my supervisor about this yet as I haven't quite decided how to approach the subject. He did say that my thesis was like a PhD and a half though the other day.
So does anyone on AskAcademia have any advice or experiences they would like to share?
| I tried to put this type of material in several appendices so that others could read about the unproductive and half-explored leads, if they wished, without letting this material detract from the main message. | 36 | 18 |
Why do phone/laptop screens have such low contrast in sunlight? Other things (e.g. books) increase their contrast in the sunlight. | Whoever invents a monitor that works properly outdoors will be very rich.
**EDIT: Okay, so I got totally into this, and I've tried to fully answer it myself. See below. I'm looking for real scientists to correct anything and everything I've said!**
We start out by defining what we mean by the "contrast". In subjective terms, I mean [my ability to distinguish between two things](http://en.wikipedia.org/wiki/Contrast_%28vision%29). My eyes distinguish "white" from "black" based on a difference in number of photons received per second. (Ignore color for simplicity.) That difference is relative, not absolute -- the contrast between 1 photon/second and 1000 photons/second is much larger than the contrast between 900001 photons/second and 901000 photons/second. The difference between 1 and 1000 is perceptible; the difference between 900001 and 901000 is not. The important thing is the *ratio*. This measurement has a name, "[contrast ratio](http://en.wikipedia.org/wiki/Contrast_ratio)".
Manufacturers assign contrast ratio ratings to their displays. A typical rating for a display is 1000:1. This means that, *[in a totally dark room](http://en.wikipedia.org/wiki/Contrast_ratio#Contrast_ratio_in_a_real_room)*, the white pixels on their display will emit 1000 times more photons than the black pixels. What about a book in a totally dark room? Well, there ain't no light to distinguish the white paper from the black ink, so for our purposes, the contrast ratio is 1:1. In a totally dark room, the display wins out.
Now what happens when we take these out in the sun? Let's deal with the book first. The important difference between white paper and black ink is that they reflect different amounts of light. I'll spare you frm Googling "measuring blackness" and finding scary historical cultural anthropological stuff. The way that these surfaces are measured is their [Light Reflectance Value](http://en.wikipedia.org/wiki/Light_Reflectance_Value), which is the percentage of light that it reflects. [This paper](http://www.xerox.com/downloads/usa/en/t/ThreeKeyPaperPropertiesWhitePaper.pdf) suggests that white paper is around 90% (and, fascinatingly, paper can be *more than 100%* if [optical brighteners](http://en.wikipedia.org/wiki/Optical_brightener) are added). [This book](http://books.google.co.uk/books?id=g82nsBwbAs0C&pg=PA290) says that "good quality printer's ink" is about 15%. This means that the contrast ratio of the book is 90/15 = 6:1. Notice that this contrast ratio will be the same under any amount of light, unless you're in a *totally dark room*, in which case it loses its contrast entirely.
Now let's deal with the display. When the display is in the sun, it's still emitting light just like it was before. Only now it's *also* reflecting the light from the sun. The word on the street seems to be that that white pixel reflects just as much light as the black pixel does -- that is, they have a constant Light Reflectance Value. This means every pixel on the screen is also emitting a constant extra amount of light. The more that extra amount is, the worse the contrast ratio will be, just like the 1000:1 vs 901000:90001 in my example.
To work out what that contrast ratio will be, we need to drop down from simple ratios into the world of absolute values. We need to know how many photons/second the white pixel emits, how many the black pixel emits, and how many photons/second are reflected per pixel.
This (visible) photons/second thing is known as *luminance*, which is measured in *nits* (what?), or candelas per square metre. Manufacturers express the luminance of their displays as the luminance of a white pixel. [Apparently](http://en.wikipedia.org/wiki/Nit_%28unit%29), "Most consumer desktop liquid crystal displays have luminances of 200 to 300" nits. So let's say that white pixel is 300 nits. I think we can apply the 1000:1 contrast ratio to say that the black pixel is 0.3 nits.
Now we just need how many photons/second are *reflected* per pixel. Since the reflected pixels don't vary depending on the emitted pixels, we can measure this when the display is off. The number of pixels reflected obviously depends on how many are shone on the screen -- in a totally dark room, it's 0, but in the sun, it's much higher. We can express the number of reflected photons as a function of the number of absorbed photons using that Light Reflectance Value. What is the Light Reflectance Value of a display when powered off? I couldn't find references, so I used my eye instead: my phone screen turned off looks roughly like a page of black ink, so I'll use the same measurement: 15%. This means that the pixels reflect 15% of all photons they absorb.
How many photons/second from land on a pixel? This obviously depends on how bright the sun is. Now, [Wikipedia says](http://en.wikipedia.org/wiki/Luminance) that "The sun has luminance of about 16000000000 candelas per square metre". But there are wildly varying measurements for the luminance of the sun. [This paper](http://www.scenic.org/storage/documents/EXCERPT_Measuring_Sign_Brightness.pdf) says it's 6500 nits, which is pretty different to 16000000000.
I also don't know whether the "square metre" here is a square meter of the *sun's* surface or the earth's surface (?!). Rather than a measure of luminance, we probably want a measure of *[illuminance](http://en.wikipedia.org/wiki/Illuminance)*. [Wikipedia says](http://en.wikipedia.org/wiki/Sunlight) that "bright sunlight provides an illuminance of approximately 98 000 lux (lumens per square meter)". But then we need to convert lumens to lux, and other people tell me that they measure different things. Damn. I will continue using the 6500 figure.
Now, if I were to use that more sensible figure, 6500 nits, we get a contrast ratio of 6800 : 6500.3, or 1.04:1, which you can probably just about distinguish.
As well as explaining the low contrast, this also explains why your phone screen looks *dark* in sunlight, too, as almost as if it's turned off. You're seeing the Light Reflectance Value of the screen, which is like a black sheet of paper, compared to your surroundings. The actual emitted light is almost irrelevant.
Notice that I didn't talk about the iris and how your eye uses it to accommodate for varying light levels. Lots of people here have mentioned it as an explanation for the low contrast of the screen in sunlight, but according to my theorizing above, the iris is not actually relevant.
| LCD/LED (backlit) screens achieve contrast by _emitting_ varying degrees of light. books/paper/solid objects that are not backlit have contrast due to _reflected_ light (from the sun). Even at it's great distance, the sun's light is so hilariously overpowering, light being emitted by LCD/LED screens is washed out by the sun's reflected light, hence the dominant effect is the reflection of the sun's light off the TFT film behind the glass, which is rather uniform in contrast.
On the other hand, eInk screens work by using voltage to change the reflective properties of each pixel on the screen (black to absorb, white to reflect) and as a result they work great in sunlight. | 255 | 380 |
Why isn't Chemistry the main Discipline that studies Quantum Mechanics? | Many chemists do fundamental work in quantum mechanics, especially computational chemists. Platypuskeeper is a resident computational chemistry expert that could shed some light on the details of such calculations.
The issue is that the systems they deal with are very complicated, so you don't come across them until late in your degree after you've learned the mathematically fundamentals in a physics course.
That said, you do a lot more quantum mechanics in a first year chemistry class than you do a first year physics class. First year chemistry class spends it's time looking at the qualitative aspects of the Schoedinger equation and the particle in a box, which is necessary to understand orbitals and quantized energy levels for bonding. Unfortunately in first year you lack the math to go much further. | 22 | 18 |
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ELI5: How do submarines go underwater and come back up? | I mean that how do they off set the buoyancy of the air inside the hull and how do they recreate that buoyancy to come back up? | They are designed to be buoyant (lighter than the weight of the water they displace, up to a certain depth), and they pump in seawater to internal ballast tanks to increase their weight until they start to sink. To rise, they pump the ballast water back out again. | 15 | 18 |
ELI5: How does soap work? | How does it keep off bacteria/smells? | Some molecules dissolve in water, and some dissolve in oils or fats. So if you get grease or oil on you (like from your own skin), water won't do much to get it off, because they won't mix. This grime can harbor bacteria that can make you stink and make you sick.
Soaps basically contain molecules with one end that dissolves in water and one end that dissolves in oils, so that when you lather it up on your skin, it can stick to the grime and at the same time stick to water, so the water can wash the grime away. | 19 | 19 |
ELI5: What's the purpose of water towers and why are they built so high up? | They store and provide pressure for water.
You know how you can be on the second floor of your house, turn on the faucet, and the water comes pouring out? You don't have a pump in your basement forcing the water up, instead, you have a water tower forcing the water down via gravity. Since your second floor is at a lower elevation than the water tower, you have positive water pressure. If you're higher than the tower, you'd need mechanical assistance to bring the water to your floor.
*edit:
The water is pumped up to the tower, but by nature of its size, and storage capacity, the pumps can be run when electricity demand is low. | 833 | 858 |
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ELI5: How do voter I.D. laws discriminate against minorities? If the reason is the cost of the I'd to the voter, why does the state or federal government not provide I.D.s to poorer people at little to no cost? | Cost isn't just measured in money, it's also measured in time. Let's say you a) live in a city that isn't as dense as NYC or Chicago, and b) don't own a car. So you ride-share with your neighbor to get to the bus route you need to ride back and forth to your job. This basically has the effect of turning your 8 hour work day into a 10-12 hour work day. Now you need to find time during normal business hours to get to a state-authorized agency for issuing ID, and god help you if you don't have a copy of your birth certificate because now you need to go to another state agency only open during business.
Now if you're high school or college-aged, getting this time isn't necessarily a huge drain on your resources. But if you're a single mother with two kids who also need to be watched during the day, visiting a couple of state agencies for a couple of hours of potentially wage-earning time is a huge deal. | 85 | 92 |
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[Steven Universe] Why Earth? | I mean, why was Earth of all worlds chosen to become a colony? Gems are seemingly immune to harsh environmental conditions (Peridot mentions that their projected bodies can adapt to any world) and so in our solar system alone they had dozens of other planets and moons to choose.
Edit: grammar | It seems that Earth's potential for life made it better suited for creating new gems. The fact that the Kindergartens leave the land around them drained of the potential for life seems to indicate that some aspect of the process drains energy from the planet. Perhaps only planets that could naturally form life on their own are possible locations for colonies?
Sadly, our information on Gem Homeworld is spotty at best. | 19 | 15 |
ELI5: Who is gaining from all the money spent during elections? | The majority of the money is spent on advertising, so who benefits?
* TV stations
* Radio stations
* Google, Facebook, and other companies with big online advertising departments
* Everyone who has a website that's monetized using online ads
| 87 | 149 |
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Has PTSD due to trauma and/or violence affected humans for centuries or is this a more recent phenomenon? Have there always been long-term effects when an individual experiences trauma and/or violence? | Trauma is a natural phenomenon with a purpose. If a person in our prehistoric past were to live in a particularly dangerous place and time, they would become “traumatized” and become hyper-vigilant to threats. They would constantly be on edge, scanning their environment for threats, and would go into a fight or flight response extremely easily. This would give them a competitive advantage and increase their chances of survival in a dangerous environment.
However, in the modern day and age, most people in developed countries live in relatively safe environments. So when a person is traumatized by some event or series of events they also become hyper vigilant to threats, they also become constantly on edge and go into a fight or flight response extremely easily. However, this way of being is not at all adaptive to the modern, relatively safe world that we live in (quite the contrary). | 135 | 78 |
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Why do electrons have spin 1/2 and photons have spin 1? | I learned in quantum mechanics that electrons are fermions and fermions have half integer spin, and that photons are bosons and bosons have full integer spin. However, this was always just stated as fact, and we didn't derive it. Is this just one of those measured quantities, like the charge of an electron? Or is there some theoretical way of showing that electrons must have half integer spin and photons have full integer spin? | In the Standard Model these are postulates. In other words, you can't derive the fact that the electron has spin 1/2; indeed, having spin 1/2 is one of the properties that makes the electron an electron, by definition. Other theories might be able to deduce the particle content of the universe from more basic laws, but none have been confirmed so far. | 10 | 17 |
CMV: Democracy today lets demagogic pseudo intellectuals come into power through elections where unaware majority votes based on intuition rather than rational critical thinking. | Democracy is flawed on many levels. Democracy today lets demagogic pseudo intellectuals come into power through elections where unaware majority votes based on intuition rather than rational critical thinking. If there's a form of governance, where only a few learned individuals decide on a non-tyrannous intellectual as their leader, then a nation adopting such a method of governance can prosper at a much greater rate than a nation where "democratically" elected incompetent leader struggles to find the balance.
The whole point of democracy when it got established must have been to give the general public a sense of power and chance at not being subjected to tyrannous oppression. But, when did it become about demagoguery, propaganda and corruption?
How can democracy save the nation? Or, rather, how can a nation today save democracy? | > If there's a form of governance, where only a few learned individuals decide on a non-tyrannous intellectual as their leader, then a nation adopting such a method of governance can prosper
The problem is with who defines 'learned', 'intellectual' and 'prosper'. For example, a theocracy can fit this description easily, and they will even tell you that they "prosper" even if everyone's dirt poor, half the population is discriminated against, and technology, health and education are virtually nonexistent, because that way of life ensures everyone there gets to heaven (and at a median age of 36, too!).
Democracy, on the other hand, can give power to demagogic pseudo-intellectuals, but if the democracy is strong enough, even when such individual is in power, their capacity to do damage as substantial as described above is very limited. | 28 | 106 |
ELI5: why does the human body experience such intense reactions from drug withdrawals? What exactly is happening? | Drugs are substances that are chemically similar to stuff our body uses for internal communication. Morphines for example are similar to endorphines (hence the name, endo=inner)
If you take the drug the job of that internal substance gets done way too much. But your body isn't dumb. It knows thats too much, so it stops producing that internal chemical on its own when you supply way too much from the outside. The receptors also get more resistant from the constant firing, wich is why you build a tolerance.
Now if you stop doing the drug the exact opposite happens. Now there isn't enough of that chemical in your body, and it takes a while for your body to readjust.
And thats pretty dangerous, as these chemicals control basically everything your body does, including bloodpressure, breathing, emotions, ... | 96 | 67 |
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CMV: As a gay male, I think its better not to get close to Middle-Eastern immigrants I come across. | I live in area with a fair amount of immigrants, and honestly, as a homosexual man, I think its best not to be friends with the immigrants from Middle Eastern and Muslim majority countries. To clarify, I'm referring to the ones who live there their whole lives, not moved when they were really young and are essentially westernized now.
The reason I believe this is because to my knowledge, they are the least accepting of homosexuality; a lot of the countries that punish homosexuality are there, [and most of the ones that have the death penalty for it, are in the Middle East.](https://en.wikipedia.org/wiki/LGBT_rights_by_country_or_territory) Also, to my knowledge there are no major LGBT rights movements in this part of the world, and the small movements that do exist, the people are usually considered outcasts. [I gather this opinion due to a Pew Research study I saw,](http://www.pewglobal.org/2013/06/04/the-global-divide-on-homosexuality/) and similar studies I've seen on this subject have gotten similar results.
Now, I'm not suggesting that we ban Muslims from entering the country, but I do feel concerned about letting in groups of people who have a culture and religion that has view negative views of homosexuality, and where bias and violence against gays is widely accepted. While I'm not suggesting this ban, I also couldn't force myself to do anything to fight against it, knowing that the majority of these people are probably okay with violence against me, I think I would feel safer with less of them around. But I'm mainly saying it's probably better for me not to befriend them, because when they find out I'm gay (most people say they can't tell I'm gay) they will probably be uncomfortable and want to end the friendship and probably think less of me.
So, because I probably sound bigoted as fuck, CMV
Edit: think you for all of your responses, and Im sorry for not getting back to you because Im at work. But I will get back to the responses tonight. Im really grateful for all of your responses. | Among the ways opinions can be changed about homosexuality is just personal experience with gay people, and seeing they're not really different or scary in the ways that people can assume.
There may be some risk that's above befriending other demographics, but you can always get a feel for the people and decide not to tell them if they worry you in any way.
It's a personal choice for you, there's potential for negative or positive outcomes, and while you may be able to predict before taking risk, you can't know with certainty.
| 264 | 507 |
What is the purpose of humans having different blood types? | To unpack that question - I understand the basics about blood types as far as antigen and antibodies, and why one blood type rejects another. But from an evolutionary perspective, why would we develop different blood types? Or is it possible they are just mutations? | Having different blood types, and having a significant amount of genetic variation at the molecular level in general, prevents parasites and infectious diseases from being able to spread as easily from person to person. That's not to say that it's impossible for a parasite to adapt to multiple "environments", but it does make it significantly more difficult to spread. In plants and animals where there is little to no genetic variation, diseases can spread much more quickly.
An example of this is the fungal diseases that can quickly wipe out genetically-identical cultivars of crops like bananas and oranges. Since every plant is genetically identical, diseases can quickly evolve to be very efficient at infecting that particular cultivar. (This doesn't happen as often in the animal kingdom because it's quite a bit harder to clone animals than it is plants) | 18 | 15 |
ELI5: How did country dialing codes come to be? | I was on https://countrycode.org/ and noticed that, while USA and Canada use "1", no country uses "2", and all of them seem random (a few single digits, a few two digit, most are three or four digits). Is there an explanation? | Country codes are assigned by the International Telecommunications Union (ITU), an United Nations organization.
When a country becomes recognized by large, they petition for an area code, and are assigned one by this ITU.
The first letter of the contry code is determined more-or-less by continent/region. US and Canada begin with +1, Mexico and South America with +5, Europe with +3 and +4, and so on. (The logic behind choosing these numbers goes to old dial telephones. It was faster to dial a lower number, and regions with more available communications got lower numbers (except Africa managed to get +2, who knows)).
The following numbers are similarly chosen, a bigger, more advanced country within these regions will get a smaller number than a smaller country; like how the Netherlands has +31 but Macedonia has +389.
Tl;dr, the first number is separated by region, and following number(s) are generally chosen based on how big/advanced they are; countries with more activity will typically have lower numbers for faster dialing | 17 | 16 |
ELI5: Why is it that certain numbers are significant across different religions/cultures? | Is there any reason that certain numbers are repeated across different religions/mythologies and within popular culture? Do different numbers resonate with us in different ways? Do we subconsciously assign significance to ordinary numbers?
Examples:
Jews wandering 40 years in the desert, the flood lasting 40 days, Jesus fasting 40 days, Buddha meditating 40 days.
10 commandments, 10 plagues
On the seventh day, 7 deadly sins (to finally cite culture, 7 dragon balls and 7 chaos emeralds) | I think many of these are attention bias. You could find examples of many of the lower many cultures:
* 2: Yin & Yang, Adam & Eve/Cain & Abel/Jacob & Esau
* 3: Holy Trinity, three wishes, "I divorce thee" three times, 3 goddesses of the Zorya
* 4: Four elements, four humors, 4 creatures in the chimera, four winds, four leaf clover
* 5: Pentgram as an occult symbol, 5 books of the Torah, 5 Pillars of Islam
* 6: 6-6-6 mark of the beast, 6 symbolic foods in a Seder plate, Six articles of Islamic belief
* 7: 7 days of creation, 7 levels of hell (in Islam), 7 Dragon balls
* 8: Noble Eightfold Path in Buddhism, circumcision on the 8th day after a child is born, 8 gates to heaven in Islam, the Eight Immortals in China
* 9: 9 is a complete, perfect and divine number in Hinduism, Odin hung on the ash tree for 9 days, Ramadan is on the 9th month of the Islamic calendar
* 10: Ten Commandments, 10 was the holiest number for pythagoreans
* 11: Tiamat creates eleven monsters to take revenge for the death of her husband, The eleventh hour
* 12: Twelve disciples, 12 tribes of Israel, 12 Petals in Anahata (Heart Chakra), Odin had 12 sons, 12 signs of the zodiac
* 13: at age 13 a Jewish boy becomes a man, 13 is considered unlucky or sinister, 13 represents the 1 prophet and 12 Imams in Islam, Jesus had 13 total disciples (Matthias replaced Judas)
* 14: Rama's exile in the forests was 14 years, Osiris torn into fourteen parts
* 15: Julius Caesar killed on March 15th, Passover is the 15th day of Nisan, Quinceañera
The lower number will have more significance in more cultures due to their simplicity and are more common. Numbers divisible by 10 will also have more significance attached due to our base-10 numbering system. | 26 | 49 |
ELI5: Why does water make grease fires worse? | Three facts: water is heavier than oil, burning oil is hotter than the boiling point of water, and when water boils, it expands- by a lot.
So when water falls onto a pool of burning oil, it sinks, then boils, then it blows oil- burning oil- all over your kitchen. | 48 | 16 |
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Did trees bear fruits before there were mammals to eat them? | As per my understanding (which is limited), fruits exist so that mammals will eat them and spit out the seeds far away from the parent tree, spreading the seeds around. Because of this, would it be biologically viable/possible for fruits to exist before mammals had evolved to the point where they could eat them? | The first angiosperms (flowering plants that all fruit trees are a subset of) evolved about 160 million years ago with their ancestors going back to 250 million years or so. Mammals first appear about 225 million years ago. Fruit trees and mammals evolved hand in hand to arrive at the mechanism you are describing of dispersal.
Fruit does not require a mammal to eat it and disperse the seed however. That is just one mechanism for dispersal. Fruits can be dispersed by water (coconut), wind (maple), clinging to fur or feathers, being defecated not just spit out, or buried as part of hoarding behavior (nuts and squirrels). So yes there could be fruit trees in an environment lacking mammals. The Pacific islands are a good example, the only native mammals on many are bats but there are plenty of fruiting trees of different types; like coconuts that don't rely on the bats. | 343 | 501 |
CMV: I am an atheist | I am an atheist, formerly of the faith, however a desire for more evidence based systems have left that faith lost, in favor of supporting evidence. I do not reject the idea that a god might exist, only that I don't know if one does, and that the supporting material I either don't believe, or I have found insufficient to prove the existence of such a god.
As I went through my studies of the bible, I not only dealt with deep personal problems that my fellow Christians handled, in my opinion, poorly, but I also came to the rather slow conclusion that the evidence for us being the product of evolution and adaptation to our environment seemed to me more supported and plausible than the support for a god. This then led me to think more critically of the material I was studying (the bible and various religious works) to see the actual message of what was being preached rather than the cultural reinforcement. Overall, I decided that the morally correct option was to leave the faith, however I am still of the mind that I do not know, and if evidence could be provided that was sufficient enough to support the existence of a god, I would take that evidence and review it and, if finding no fault in it, accept it as true. | If there were reliable, repeatable, peer reviewed scientific evidence for any particular religion then it’d be front page news and everyone in the world would follow that religion. Bottom line, every religion relies on faith which is believing in things without evidence. If you’re trying to determine fact from fantasy, faith can not get you there because you can’t distinguish one religion from another. There is no evidence in favor of any particular religion, you simply can’t test the claims they make nor the scriptures in any meaningful or scientific way precisely because they believe things without evidence. | 15 | 21 |
What books to read to get deep into ethics? | Hey I have only recently gotten into philosophy, I started off by reading The Problems of Philosophy by Bertrand Russell, and now I want to learn more about ethics in general.
More specifically, I'm curious in how you ground out a moral statement into something that you can defend against someone who attacks it. Like for example if I say "Causing unnecessary pain and suffering is undesirable", and someone disagrees with you, how do you argue against them? I'm looking for something more or less along these lines of like starting points for moral conversations. | I would look at the Platonic texts "Meno" and "Euthyphro" as a good starting point. They are both dialogues so they demonstrate how to have a debate about ethics. From there look at Aristotle's "Nichomachean Ethics", Mills "Utilitarianism", Kants "Groundwork for the Metaphysics of Morals" and Nietzsche's "Geneology of morals". These will give you a good groundwork for the major ethical theories. | 10 | 26 |
CMV: When it becomes widely available, a diet consisting primarily of 'lab-grown meat', would be more ethical than vegetarian or vegan diets. | A little bit of background: I consume meat on a fairly regular basis, however. my girlfriend is a committed vegetarian and has been since she was very young. Recently, we both read an article on recent advances in the commercialization of lab-grown meat (more on this later) and its potential benefits. At the time, I asked her whether she would consider adding lab-grown meat to her diet if it becomes commercially viable and widely available, to which she replied with something along the lines of “probably not”.
While that was basically the end of the discussion, it got me thinking about people who are vegetarian or vegan primarily due to their opposition to the killing of animals, or as a result of environmental concerns (such as clearing of rainforests/wilderness for cattle ranching, greenhouse gas emissions, etc.), and the effect that lab-grown meat would have upon them. With this in mind, I'd like to put forward the following view:
1) Not explicitly killing an animal to consume its flesh does not mean that no animals were harmed in the harvesting and production of non-meat products. It is clear that there will be some inadvertent deaths that result from any kind of farming; in the case of non-meat farming, for example, animals may be caught up in combine harvesters or other machinery, or else their habitats may be destroyed when the farmland is cleared during the harvesting process, or even when the land is to make room for the farmland in the first place. In light of this, it would seem that the realistic aims of vegetarians/vegans are to **minimize** animal suffering and environmental impact.
1) There is currently an effort to develop meat that is grown in the laboratory through the culturing of animal cells (see [this article](http://www.sfgate.com/food/article/Memphis-Meats-introduces-lab-cultured-chicken-and-11003907.php) and [this article](http://www.bbc.co.uk/news/science-environment-23576143), for illustrative examples). It is believed that these products could be commercially available as early as 2020.
3) As far as I can tell, at no point is an animal killed in order to produce this lab grown meat. It would also seem that the inadvertent killing of animals would be minimized through the consumption of lab-grown meat.
Taking these points into account, it seems to me that if you are vegetarian/vegan, and the reasoning behind your diet is to minimise animal suffering and/or environmental impact, **and** if lab-grown meat (as exemplified in the articles above) becomes widely available and affordable, then it is both logical and ethically correct to switch to a diet consisting primarily of lab-grown meat.
I look forward to having my opinion picked apart :)
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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!* | To really evaluate this claim, we'd need to know more about where the raw materials to manufacture lab grown meat came from. Cells can't just grow without some input. It's likely that whatever chemical input is used to grow the meat (aka a nutrient broth) is likely derived from plant materials, so you haven't avoided the farming issues of habitat destruction or combine harvesting you laid out in (1)
| 15 | 29 |
eli5: Why are the oceans salty? | Salt is a mineral which can dissolve in water. The water cycle has water evaporating from the oceans and falling onto the land, running back into the oceans eventually. When the water evaporates from the oceans it doesn't take salt with it so what is falling onto the land is fresh water. But as it runs over the rocks and minerals on the land some of the salt will dissolve and go with the rainwater down through streams, rivers, and eventually into the ocean.
Over a long time this means salt tends to move into the ocean, making it salty. | 31 | 17 |
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How can the morality of an action be seperated from its consequences? | In a philosophy video I saw this quote from Kant (I appologise in advance if this is dumb question I'm new to philosophy):
>Because morality is not empirical, whether an act is moral or not cannot be determined by it's consequences -- rather it must be determined by the nature of the act itself.
If this is true, wouldn't the logical conclusion be that shooting someone could be a morally neutral action? If pulling a trigger is the action, wouldn't the action itself be judged in Kant's assertion regardless of whether or not the consequence is someone being shot? | Kant argued that morality of our action depends on our intentions. If our will is good then our action is good, despite of all possible consequences. This seems reasonable if you remember that our actions don't always brings results that we expect. For example, you are a royal healer who healed a daughter of a peasant out of goodness of your heart in a plagued village. Then to your shock you found that the villagers killed the girl because they suspected her to be the evil witch who caused the plague. And they suspected her because her health suddenly improved. Her parents told them about a kind royal healer, but they didn't believe. Would be her death your fault? | 10 | 22 |
ELIF: How does the heart get stronger as a muscle? | I get how muscles grow and get larger, but how does a heart mimic this behavior? | The heart can get stronger in many ways. Transient ways include increased sensitivity to calcium, which means, for the same amount of calcium entering the muscle cells, you get more force. This is an instantaneous response to stretching the heart, it allows the heart to pump more blood if it received more (so it always has the same amount of blood left in the end of a contraction), this is called the Frank Starling mechanism. The heart can also get more calcium by releasing more of it from its internal stores and by getting more from the outside, this also gives more force (usually in response to biochemical signals like adrenaline), and more calcium is more force. These are all fast responses. When the heart is chronically (for a long time) facing high pressure like in exercise or hypertension, it needs a more permanent solution. So the muscle cells themselves grows in size (never in number when you're an adult). It does so by depositing more sacromeres which means it increases the number of the force generating units within each cell. It can either deposit them in parallel (next to each other) where the muscle cell gets thicker or in series (in front of each other) where the muscle cell gets longer. Usually, thicker means healthy adaptation like to exercise, longer means maladaptation like in disease such as hypertension. The heart also remodels in many many other ways such as metabolically and electrically all to make it contract faster (chronotropy), relax faster (lusitropy), contract stronger (inotropy), conduct electricity faster (dromotropy), or become more sensitive to electric stimulation (bathmotropy).
Edit: English | 29 | 23 |
In modern steam power plants, can the amount of power output be managed? | In modern power plants that heat water, make steam, and turn turbines through steam power, is the output set, or can the operators feed it less fuel, produce less heat, create less steam, and output less power?
I'm curious due to the nature of the power grid, where excess power just goes to ground. It is such a big waste, I'm wondering if the plants can throttle the output during non-peak times and ramp it up during peak times.
Thanks! | Different power plants have different responses, and different time scales. A combined gas cycle plant, running off Natural gas can respond to the grid very quickly increasing its power output. They are often used as load balancers as they are rather expensive to use all the time.
Other plants such as a nuclear plants cannot easily increase or decrease their power usage in a short time scale. They are used as a baseline load. If there is an outage, or suddenly power usage drops quickly they must dump power, or shut down. As shutting down is expensive you can have a resistive load balancer which will drag down the grid voltage to keep it in line with specs. This is basically a industrial sized coffee maker that heats water.
Generally for non emergency load balancing water is often used. They will pump water in reverse in a hydro plant, then when they need more power they allow it to run through the turbines again.
Renewables such as solar and wind are not comparable, as they have very strange power responses, and are controlled by forces outside of human control. However they are such a small part of the grid, it doesn't really matter. If percentage is to be increased, this needs to be addressed. | 15 | 63 |
Why do certain parts of our body reproduce
themselves when destroyed (eg skin) and others
don't? | For example, if i rip or burn the skin on my fingertips, it will grow back. Or scars are somehow covered up.. But why if we cut a person's finger, or a whole hand it will not grow again..? Can this become under certain circumstances..? Any other examples more microscopically ? | Some parts of our body contain cellular machinery to heal wounds, and some do not.
In the skin, if you have a deep cut, the stem cells (basal keratinocytes) in the stratum basale need to divide and reform into a single layer to start regenerating skin cells in the epidermal layer above them. If they are too far separated, this regeneration will be incomplete, which is why stitches are sometimes necessary.
If you cut off a finger, there's no basal structures that can regenerate and the architecture is so complex, simple cell growth will not suffice.
Other areas in your body - like your GI tract - work in much the same way.
Your liver can take quite a bit of damage and still regenerate - from as little as 25% of the original structure - largely because other liver cells will proliferate and fill the space, restoring function if not the original architecture. | 10 | 20 |
ELI5 why people blur cover their license plates when posting on the Internet since anyone can see their plates in real life anyways? | Helps prevent criminals from finding you as well as preventing someone from somehow making a copy of your plate and putting it on another car of the same make and model and color and preforming illegal acts with it. A lot easier to find something like that online than in person. | 15 | 25 |
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If one of the goals of exercise is to get the heart rate elevated, do things like anxiety or low BP help work the heart out? | I've been told to set a HR when one exercises and try to keep it above that point to maximize the workout.
I wonder: is there a difference, in terms of improving cardiac function, between running vs. anxiety, sitting in a hot shower, HR medications, etc? | Exercise produces an accelerated heart rate since the body is working harder to respond to physical stressors. While this does stress the heart, it can help reduce resting blood pressure and heart rate since it trains the heart to be more efficient.
Anxiety, chronic tachycardia, and hypotension-induced tachycardia are the heart working hard *at rest*. This is the opposite of the effect that exercise has on the heart. | 44 | 120 |
CMV:The Use of Closed-Source Software is NOT Unethical | **The Thesis I Am Challenging**
"The use of closed-source software is unethical"
**Defenses of the View**
I have run into this view quite a bit as of recent, and I'm not really sure what to make of it. I first encountered it in Sanjoy Mahajan's MIT OpenCourseware Course ["Teaching College-Level Science and Engineering"](http://ocw.mit.edu/courses/chemistry/5-95j-teaching-college-level-science-and-engineering-spring-2009/video-discussions/) where he mentions it in an off-hand remark about what file formats he uses towards the end of the series. He just casually remarks something like "Well, I prefer to use open office because I consider the use of closed source software unethical". I looked it up on the google and didn't really find him or anyone else defending this view. I know there's this sort of "information wants to be free" movement on the internet, and I'm sure this is related to it, but I'm not sure what the defense of that view is.
**My View**
I think it's preferable to use the software that is the most effective at accomplishing the task at hand, in a very utilitarian way. I don't think the closed- or open-sourced nature of the product makes one more ethical than another. If someone is willing to be paid $20 for a piece of code that I am willing to execute in a compiled fashion for $20, I don't see that piece of code, open source or not, to be an illegitimate commodity.
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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 can be argued that information is a *public good*. Basically, when people don't have the information they need to make a good decision they will invariably make bad decisions. By arbitrarily hiding that information from people you are creating a situation where others will necessarily make bad decisions that will harm them and society in general.
In terms of software this means that by hiding that information you are removing accountability that you could be held to letting people get away with overcharging for substandard work and creating cover for criminals to inject spyware or malware all the while pretending to be an innocuous program. | 14 | 33 |
I'm horrible at finding literature | This week I had a meeting with my supervisor for my master's thesis. One of the main points of feedback was that my literature review had to be more extensive and that I had to add way more papers. My supervisor was kind enough put ten minutes into searching literature together and found several relevant papers with no issue at all. Meanwhile, at home I'm using the same keywords at scholar and all I get are shitty papers. This kinda panicked me.
Apart from this I'm horrible in general at finding good & relevant literature. I just read some other theses and I'm amazed by the fact how smooth literature reviews can be (though I sometimes look up the paper to which was refered and I can't find the statement which was made at all). Right now I feel like a major failure who doesn't deserve his master's degree but I'm trying to keep myself calm. I was wondering if someone has some good advices regarding finding literature or maybe even know some good reads about finding literature (oh the irony). | Here's what works for me. Try to find a recent review paper of the topic you're interested in. Not only are these papers good for giving you an overview of the subject, you will have a list of references they used, which you can then look into yourself. | 88 | 46 |
[Mulan] Why is Mulan the only person with an ancestral guardian? | Ancestral guardians usually work behind the scenes, invisible and undetectable, but still able to influence matters with their vast powers. If the Great Stone Dragon had awoken like the ancestors had intended, then that's likely how it would have operated.
Mushu is not nearly so powerful, so he had to take a more hands-on approach.
Thus, it's perfect possible that other people had active ancestral guardians watching over them, it's just that these guardians were not visible. After all, Shang and the other soldiers do get rather lucky at times. | 29 | 18 |
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If soil comes from dead plants, what substrate did the first terrestrial plants grow on? | This question was asked by my 8-year old as part of a long string of questions about evolution, but it was the first one where I didn't really know the answer. I said I'd look it up but most information appears to be about the expected types of plants rather than what they actually grew on. | Generally bacteria are the first things to colonise bare rock and provide a substrate for other micro-organisms. Simple multicellular organisms like lichens can thereafter colonise the rock. They reproduce quickly and can survive the harsh conditions, and many species don't need soil. Its these plants that start to lay down soil as they die off and decompose, providing a substrate for increasingly more complex species.
What your 8-year old is asking about is called "ecological succession" and is the process through which an area can go from bare rock to a rich forest over a hundred years. You can see the early stages of ecological succession all over the place, particularly in concrete urban areas that have been neglected and are in the early stages of colonisation. In fact your local hardware store will sell lots of products which are the armoury of the homeowner in the struggle against the primary colonisers of ecological succession. | 5,524 | 3,806 |
How can I as a layperson get better at judging whether a scientist is
trustworthy? | What parameters are important when judging a scientist's trustworhiness?
There may be a better word than trustworthiness. By trustworthiness I mean what it says in the first two lines of the Wikipedia article:
"Trustworthiness is a moral value considered to be a virtue. A trustworthy person is someone in whom you can place your trust and rest assured that the trust will not be betrayed."
Peace out. Amazing forum! | 1. Are they an actual research scientist? Put their name into Google Scholar. They should have many publications including some that have been cited dozens or hundreds of times.
2. Are they actually talking about their field of expertise? A nuclear physicist is not trustworthy when talking about disease resistance.
There are exceptions, and other things to take into account, but those are the main things. | 29 | 27 |
Are forests and jungles growing more rapidly now that there is an increase of CO2 in the air? | In photosynthesis there are 3 metabolic pathways for carbon fixation from CO2. In forests and jungles we are concerned with the C3 and C4 pathway (the CAM pathway is only found in arid plants). These pathways impact how a plant responds to elevated CO2 levels.
In the C3 path oxygen competes with CO2 in the presence of the first enzyme, RuBisCO. Meaning that the enzyme can't distinguish between oxygen and CO2. Incorporating oxygen ultimately results in a toxic compound later on that must be disposed of through photorespiration which uses energy. So the ratio of the gases in contact with RuBisCO matters. More CO2 successfully being bound means less energy lost to photorespirstion. Increased CO2 can benefit these plants. 85% of plants use this C3 pathway including rice, wheat and trees.
The C4 pathway evolved next and it removes the energy lost to photorespirstion by only allowing RuBisCO to bind CO2. This is accomplished by putting the enzyme in a newly evolved chamber and selectively exposing it to only CO2. These plants are pretty much already maxed out at what they can handle at current CO2 levels. They don't get any benefit from rising CO2 levels. These include plants like corn and grasses.
Forests and jungles contain both C3 and C4 plants. C3 plants have the capability to grow more in the rising levels but climate change also bring along big temperature and rainfall shifts which can negatively impact the health of the C3 and C4 plants alike. | 43 | 105 |
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[ELI5]: Why do pigs go through a big transformation if they're introduced into the wild? | How does a domesticated pig turn into a wild boar when released to the wild? | A creatures phenotype (physical manifestation) is dictated by its genetic code. There are actually different ways in which genetic code will be expressed depending on the environment that the creature finds itself; this phenomenon is called epigenetics. There is another phenomenon called neoteny in which creatures retain juvenile characteristics depending on their environment, and will quickly mature given certain conditions.
So just as an example to illustrate the point, say that a pig is in a farm and is fed and shielded from predators. The chemical profile of this pig might show low levels of testosterone because there had not been any circumstances that would have precipitated the production of excess testosterone. When the pig is let out into the wild, it is suddenly in danger of predators and starved of nutrients, so the relevant chemical cascades kick in which will be conducive to its survival, and these may actually change the way it physically appears (testosterone --> greater hair production, etc). | 232 | 435 |
ELI5 Why do some colours go well together and some colours not? | Some part of it is seeing which color combinations we're already familiar with. For example, if you were to pair leaf green with almost any shade of red, pink, yellow, orange, or purple, they would work together. It's a very common set of color combinations in fashion, interior decor, and graphic design. We also have all seen it (assuming you're not color blind) in nature, as flowers have these color combos with their leaves. Green is practically a neutral to us. For a similar reason, navy blue is considered a pseudo neutral color that matches with almost every other color; it's also the color of the night sky and the ocean. We've all seen it many many times, so seeing it again is comfortable.
The color combo of red, yellow, and blue is not inherently childish, but some people associate it with preschool or elementary school related things, because it's often used for kids' stuff in marketing and product packaging.
Basically, we become familiar with certain color combos, and sometimes we start associating them with certain things because we see them in a specific context so many times. If we like that context, we are more likely to like that combo. If we don't like that context, we are less likely to like the combo. | 29 | 54 |
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CMV: American Christians have an obligations as Christians to follow church teachings personally, and as Americans to not inject church based agendas into the political arena. | Separation of church and state is a foundational principle of governance in the United States. The founding fathers were careful not to identify a particular deity as having given us our inalienable rights and it is the first stated principle in the Bill of Rights. Also, the First Amendment guarantees the right of American citizens to violate the 1st, 2nd, 3rd, 4th, 9th and 10th Commandments, as laws are meant to restrict as little as possible, while religious proscriptions demand adherence to a specific code of conduct. Thus the difference between crimes and sins.
American state makes a point of not wanting to interject in the affairs of the church - in so far as to not even requiring filing of taxes for most churches, nor collecting any, and disassociating itself from even knowing about the financial affairs of the church.
In so far as principles of liberal democratic governance drawing from Jewish and Christian religious doctrines, separation of church and state is also part of Christian teaching - Jesus himself taught to "Render unto Caesar the things that are Caesar's, and unto God the things that are God's." Matthew 22:21.
The context of the quote is also notable. The controversy was over paying Caesar's taxes, which required a Roman coin, which had an image of Caesar in the front, and believed to have an inscription stating "Caesar Tiberius, son of the *Divine* Augustus", making it a graven idolatrous image, that had to be brought into the temple for tax payment.
The faithful also had no way of knowing that their tax payment would not be used to build more idols, temples to Roman gods, or for other purposes they would consider blasphemous.
Living in a religiously diverse state with an idolatrous official religion, whose morality differed greatly from those of Jews and Christians, in a generally permissive society, was not a religious problem for Jesus, nor need it be for present day evangelicals.
It also seems entirely possible for a reasonable Christian to have secular policy positions contrary to teachings of the church, as church and state are separate matters. It also seems reasonable for a Christian to accept removal of 10 commandments displays from government buildings as correction for a long-standing error in judgement on the part of the government, and to happily pay taxes, knowing some of it will go to fund abortions or teach evolution.
My position is that evangelical forays into politics are presented as matters of faith and religious conviction, but this claim has little theological basis. Furthermore, the policy positions being pushed seem arbitrary, and also don't seem to have theological basis.
Therefore, making support for these church political positions a matter of faith for evangelicals and christians seems erroneous, as well as the general contention that use of their political influence/encroachment of church into state is an exercise of their rights as faithful Christians.
Please change my mind.
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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!* | Personal political beliefs and how you vote must be based on ethics, and if you are religious your ethics will be shaped by said religion. Therefore it is not possible to fully separate the two as you are wanting. | 14 | 17 |
ELI5: Why are there so many species of most living beings but only species of humans? | This is less a question about biology and more about human categorisation. We see quite a lot of distinction between ourselves and our nearest relatives (apes), in no small part because we're extremely familiar with ourselves and the differences between us and apes are a pretty big deal as far as our priorities are concerned. When we compare, say, a red fox and a grey fox (which are from entirely separate genera - *Vulpes* and *Urocyon*), the differences don't seem all that significant to us. They have a similar shape and similar enough behaviour as far as we care, so we dump them in the box labelled 'fox'. Most of the time we don't really care which kind of fox a fox is. Most of the time we care quite a bit whether something is a human or an ape!
(In fact, many of those categories are specific to a particular language, and things one language considers 'the same animal' may be quite separate to speakers of another language. Japanese, for example, has no one word for 'otter' - it has *kawauso* for river otters and *rakko* for sea otters.)
It *is*, however, reasonable to ask why there's only one extant species in the genus *Homo* (which humans are in), when other genera have many more species. This is in large part because humans have outcompeted or otherwise outlasted our nearest relatives, and other species that are conceptually closer to us than living apes are all gone now. It's also in part because genera are *also* human categorisation tools, and as much as they're intended to be independent of human bias, we don't always know what should be in the same genus and what should be in separate genera. It's not infrequent for genera to be split (or merged!) after taking another look at them. Really, the criteria aren't all that straightforward, and it's not uncommon to come across situations where there's no clear line at all between one species and another or one genus and another. What counts as 'one kind of living thing' versus 'another kind of living thing' ultimately is a purely external categorisation decided on by humans, even if the differences those categories are based on are real differences. | 60 | 31 |
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ELI5: Why isn't getting checked for cancerous tumors, or tumors in general, a routine process? | I feel like tumors are only discovered when the patient feels as if something is wrong, and by then it is usually too late to take effective action. | The problem is that there are very many downsides to routine checks. Too many downsides, in fact.
First of all, we do not have the resources to preform routine checks on everybody. In many places, there are already long waiting lists when people need certain types of scans or care. If we tie up our limited amount of scanning equipment and personnel that can use these machines and interpret the results with millions of people who don't even need them, the waiting lists will only get longer and longer.
Secondly, body scans are not magic. They can detect if there are irregularities in your body. They cannot immediately detect whether this irregularity is something to be concerned about or not. Most of us have irregularities in our bodies that are absolutely nothing to worry about, just a result of how we aren't perfect beings and don't grow perfectly. If everybody gets routinely scanned, all of these irregularities are going to pop up and doctors will pretty much be obligated to investigate them further. Even though 99% of them are absolutely not any danger to you. That means more tests (so again, more strain on our limited resources) and also means more stress
Which brings me to point three: quality of life. Basically, routine scans do not improve quality of life. In rare rare rare rare exceedingly rare cases, they might detect something slightly earlier than it would otherwise have been detected. In most cases it is going to detect harmless irregularities, which will lead to people having to undergo more (and sometimes painful testing), which they will have to wait longer for due to the longer wait lists, which all accumulates in a huge increase in stress. All to tell you something they knew already, namely that there is nothing wrong with you. Basically, the very marginal benefits of a system like this do not outweigh the much more common adverse effects (all the extra stress and pain of tests that people will experience and the added wait time to everybody else who *does* need these tests and might be in a worst position due to the long wait), so we don't do it. | 62 | 144 |
Could exposure to radioactive radiation be "good"? | So I'm just curious no I'm not gonna try to expose myself to radiation and I know it's very likely to cause permanent damage or kill you but was I'm wondering is whether there is a chance when it changes your dna that it makes you "better" | Let's be clear here, ionising radiation (as opposed to non-ionizing radio waves, WiFi signals etc.) causes changes in biological specimens by changing/damaging cellular structure.
This occurs when the charged particle - an alpha particle (He2+ ion), beta particle (an energetic electron, e-) or a gamma ray (high energy photon) passes through a biological structure.
Given that these particles are atomic sizes or smaller, and the proteins forming the DNA that is changed consist of tens or hundreds of atoms, and human DNA is literally 3.2 billion base pairs of proteins, the chances that you randomly expose DNA to radiation and it makes an improvement are about the same as randomly picking a word from the dictionary, and then randomly turning to a page of your favourite book and replacing the 57th word on that page with the one selected from the dictionary, and then making your favourite book better! And this is for the single cell affected.
For radiation to turn someone into spiderman or something requires the radiation to modify each and every relevant cell in the body in the same way. So now consider your book experiment, and imagine that EVERYBODY IN THE WORLD has to do the same with their own favourite book. Statistically impossible, right?
Now, the human body has some kind of system to guard against these changes (which happen more than you'd imagine) since we live in a naturally radioactive environment, albeit at a relatively low level. When cells are changed, some biological process switches off and the individual cell dies, and another one grows to replace it. When this doesn't happen right, people develop cancers. And this is why excessive radiation exposure kills people, because too many cells die at the same time.
Theoretically, if this process could be understood and controlled, it could lead to improvements, but not by the process of making things better, but by killing off some cells that were less efficient than the others at whatever they did, or indeed cancerous. This is the radiotherapy treatments that others have referred to. | 21 | 15 |
[Fullmetal Alchemist] What is the farthest distance an Alchemist can transmute? | Like could Ed transmute on one side of central city to affect the other side? | Normal alchemy has its effect centred within its transmutation circle, though the line of effect can extend beyond it. Example of distance alchemy like that include Armstrong's artillery rocks (where the transmutation is instant but the rock is thrown by force) and Mustang's flame alchemy (which is considered extremely complex, in that the effect really is centred on his hands BUT travels through the air with precision to the target at virtually lightning speed).
People like Ed are somewhat of an exception due to their not using a circle, but the general limitation remains where the transmutation is centred on their point of contact (where his hands touch usually, though sometimes he channels out of himself elsewhere like his feet). He can achieve a limited degree of distance alchemy, but only where the effect is extremely basic because he's actually changing everything from where he's standing TO where the effect is occurring. That's why his little "create stone walls" trick is actually so mindblowing: nobody else can do anything nearly that complex, AND he does it on the fly meaning they can come out of anywhere.
To affect something across Central, there's a few ways this could be accomplished. Option one is explored in the series: just make a giant transmutation circle that encompasses both you AND is centred on the location you're trying to affect. But that's not what you're trying to do.
Option two, which is Ed's style of alchemy, would require him to have clear line of sight AND line of effect across that distance. With your example of Central City, that's definitely impossible due to buildings. So let's move this out into an empty field. Now, he needs to know what he's doing... as well as the composition of *everything between him and his target*. This isn't technically impossible, but it sure takes out 99% of opportunities. So again, let's move. Maybe a perfect stone plateau? It's now a safe bet that the ground is "stone" (whichever stone that may be) from here to the target location. *Now* he could make a statue appear from across that massive distance, by knowing all the necessary details.
Option three is abandoning alchemy, and switching to alkahestry from Xing. It's specifically focused on distance transmutation, as long as it's along "ley lines" which alkahestry practitioners can somehow identify. Drop a circle on the opposite side of the city, trace a linkage to where you are and make a mirrored circle, and voila! | 30 | 26 |
Do peoples eyes really "change colour"? | Color is determined by both physical properties of an object and the properties of light around it.
The pigments in our eyes which determine what wavelengths are absorbed and reflected do not change.
However, the color can change based on the type of lighting (florescent, incandescent, candle, sunlight, etc) and the dominant colors in the immediate environment, which can include clothing. Both of those things change the distribution of wavelengths that hit the eye (and everything else) and so also change the distribution of what is reflected back (which is what we think of as 'color').
Additionally, in bright light, where those effects are minor, putting on a very bright green shirt, for example, might make the person's eyes look less green in comparison. This, though, is purely a perception issue of humans, and so the color would still be the same if measured by say, a camera, which is not the case above. | 60 | 126 |
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If every language is eventually compiled into the most basic machine instructions then why do languages like C and C++ run faster than Java and Python? | I don’t understand why lower level languages run faster than higher level ones if they are all eventually compiled into machine code. | First of all, you should distinguish between a language and its implementation(s). How and whether code in a language is translated to machine code can and does vary widely between different implementations of a language. For example the Python implementation PyPy has a JIT compiler, but CPython does not.
> If every language is eventually compiled into the most basic machine instructions
This isn't true. Not every programming language implementation emits machine code (as mentioned above, CPython doesn't), nor does every language have at least one implementation that does.
Beyond that, it doesn't only matter whether machine code is generated - it also matters *which* machine code is generated (also *when* in the case of JITs). For example, a naive compiler for a dynamically typed language might generate type checks for every operations (while a more complex, optimizing compiler still wouldn't be able to avoid doing so in all cases) while a compiler for a completely statically typed language would have no reason to do so. Similarly virtual function calls will necessarily involve extra lookups that can't always be optimized away.
In addition, a language might use big integers as their default integer types, heavily feature reflection, or contain plenty of other features that tend to be costly to implement.
Even among implementations for the same language, performance can differ significantly, so it's not surprising that implementations for different languages with different features and requirements would have even more differences in performance.
And then there's of course the fact that some languages simply have more mature (and thus better optimized) implementations than others based on how long they've been around, how widely they're used, and how much performance is even a priority. | 52 | 62 |
CMV: Humanity has yet to master or even invent a form of government/economy that would sustain us as a species, on a massive scale, indefinitely, in outer space. | First, let’s presume a few things:
1.) Humanity will eventually have to venture off this planet if we are to survive as a species because Earth is a very volatile place and could eradicate us fairly easily given the long view of its history.
2.) We have mastered the technology to create and maintain massive self contained environments powered by finite and renewable resources, whether they be large scale space stations, or planetary habitats.
3.) We have mastered medicine, agriculture, and any other technologies required for our species to flourish and survive indefinitely in such an environment.
I hold this view because we do, in a way, already live on a sort of space station, with finite and renewable resources, and seem to be living in a very unsustainable way. I see our time here on Earth as a sort of practice run for the big game out amongst the starts I guess. As of right now, we don’t stand a chance, specifically in terms of governing people and economies in a mutually beneficial and sustainable manner.
So please, for the sake of humanity’s future, change my view. | We have all sorts of governments that could work under such scenarios. We have testbeds dotted all over the planet investigating long term survival for small groups of individuals just for such an occasion as we go to space. The military structure in particular features heavily because it's already a system predicated on group survival over most other factors.
The problem isn't having a system. It's we don't care to implement such a system. Because these systems don't grow as well or distribute power as some would want. We measure our success with economics, liberty etc. And we vote based on individual benifit. Things that don't feature well in the types of systems designed to promote austerity and survival at all costs. | 396 | 2,502 |
How could you recursively find all permutations of a list? | I'm trying to write a program that does this, but I'm having trouble thinking of how to solve this algorithmically. I've been trying to understand other people's solutions for hours and I'm just not getting it. Can someone please try to explain what algorithm you can use to recursively find all permutations of a list of any size? | Recursion is all about defining the simplest possible case and building up from there. How do you find all permutations of [1]? Easy. How about [1,2]? Still pretty easy. The pattern starts to reveal itself around length 3:
[1,2,3] [1, (permutate [2,3])]
[1,3,2] ...
[2,1,3] [2, (permutate [1,3])]
[2,3,1] ...
[3,1,2] [3, (permutate [1,2])]
[3,2,1] ...
See it? All the permutations of [2,3] start with 1. All perms of [1,3] start with 2. This is the basis for using recursion.
Here's some pseudo code:
def permutations(list):
if len(list) == 1:
return [list]
result = []
for x of list:
for p of permutations(listWithoutX):
result.push([x, ...p])
return result
Keep in mind that you want the index of x to efficiently grab the listWithoutX. In JS, you could do:
listWithoutX = [...list.slice(0, i), ...list.slice(i + 1)]
Because `list.filter(v => v == x)`will iterate over the list instead of just chopping it up.
tl;dr perms of list with length 1 is itself, perms of any other list is perms of all lists 1 length less with whatever's missing in front. | 17 | 24 |
CMV: Illegal immigration in the USA would be far less common if there were strict penalties for employing illegal immigrants. However, this won't happen because of intense lobbying | From my knowledge and perspective, most policies aimed at curbing illegal immigration are aimed at the illegal immigrants. You even frequently hear the comment: "they are breaking the law" or "they need to follow the laws of this country". However, illegal immigrants have very little motivation to follow immigration law. If they follow the immigration law, they are denied entry into the USA and gain no benefit. If they violate the law, they gain better pay and only risk being caught and possibly deported. There is little risk and a great deal of reward. You would be a fool to just "follow the US law"
Employers, on the other hand, actually have some reason to not employ illegal immigrants(see below). However, the benefit is only seen if everyone(or mostly everyone) is following the law. The current enforcement regime seems to strongly encourage businesses to cheat. Many small business owners I know employ illegal immigrants. Now, they don't knowingly hire illegal immigrants, but they are well aware that many of their employees are probably illegal immigrants. They know that the social security numbers they were given are probably fake, but as long as they run them through the government required website, they feel that they are clear of any consequences. However, these people will admit that they employ illegal immigrants.
*Example of strict law enforcement for suppliers: Alcohol sales*
Most states do not worry about underage buyers of alcohol. Rather, they focus on alcohol retailers and have strict fines and penalties for any supplier caught selling or providing alcohol to a minor. While minors still get access to alcohol, it is nearly impossible to find a minor drinking at a bar or buying liquor at a liquor store. In fact, many liquor stores/bars will deny sales to individuals who are not minors out of an abundance of caution.
I am not saying that no minor ever buys alcohol with a fake ID, but I would say that there are far fewer minors buying alcohol than illegal immigrants working at large corporations. Why? Because bars/restaurants/stores suffer a severe penalty if they are caught violating the law.
Please change my view.
**Most laws benefit everyone in society(my argument explained)**
Most laws actually benefit everyone. The law against theft actually benefits everyone eventually. If theft was legal, no one would benefit. A thief might temporarily gain some money by stealing your car, but then he would immediately lose it when the car was stolen from him along with his other property.
If hiring illegal immigrants was totally illegal, the companies would actually be fine. They might need to raise their prices, but they would also know that all of their competitors would also need to raise their prices as well. | To go somewhat orthogonal to your suggestion, wouldn't it be more reasonable to simply allow those people to immigrate legally? Your view posits that there is are industries that are built on exploitation of underpaid labor, and additional industries built on providing false social security numbers. It seems like allowing people to *legally* immigrate to the United States for the purpose of performing those jobs would serve to limit the exploitation, especially since as legal residents they would be better able to report any further exploitation by their employers.
Now, you could combine that with more penalties for exploitative labor practices or hiring under the table, but that doesn't solve the issue that those industries (apparently) cannot find enough labor without turning to immigrants. | 12 | 113 |
How do astronomers determine the distance and size of a star or exoplanet? | There are many ways to measure the distance to an object in space. For the closest stars you can use something called parallax.
If you put your arm out in front of you and hold one finger up and look at it with one eye and then the other it will look like the finger is at different places! Now try moving the finger to different distances from your eyes and the "jump" in distance will be larger the closer the finger is to your eyes.
This is because our eyes are separated by a small distance and if we know this seperation and the apparent difference in distance of the finger when looking with the different eyes we can work out the distance between the eyes and the finger.
Now if you look at a star and blink your eyes like this you won't see any difference.. But if you look at a star today and then wait half a year the Earth has moved to the other side of the Sun and this effect will be measurable! And since we know the distance to the Sun we can work out the distance to the star we are observing.
Now if the object we are observing is to far away for this effect to be noticable we must use a different technique, and there's quite a few! The most common techniques include so called standard candles and red shift. A standard candle is something that always shines at the same intensity, that gives of the same amount of light no matter what. The most famous example of a standard candle are a special type of supernovae (SNe), namely type Ia SNe.
These SNe occur when a white dwarf leeches material from a companion star. When the white dwarf has leeched enough material to reach a certain threshold, known as the Chandrasekhar limit, the white dwarf will explode and this explosion is very well understood and we know how much light it give out as they all occur under the same circumstances. By measuring the intensity of these SNe we can figure out the distance to the SNe since light intensity decreases with distance.
Another standard candle are Cepheid variable stars. These stars vary in intensity and the period of their variation is tightly associated with its luminosity and be looking at how much of the light reaches us we can calculate the distance.
As for red shift, that is for the very large scales! As an object moves through space the light it sends out gets shifted, just like a sound wave does which you can hear as an ambulance drives past you. As it approaches you hear a higher pitch and after it has passed you hear a lower pitch. The same thing happens with light waves. Because of the expansion of the Universe this means that objects separated by some distance will also be moving apart at a speed correlated to the distance, so by looking at how much the light has shifted we can see how fast the objects are moving compared to each other and at large scales this movement will be dominated by the expansion. (The light also gets stretched further from the expansion in another way but that's not necessary to think about here.) | 37 | 110 |
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ELI5: Why is it that after looking at a bright light source, and then closing your eyes, you see a colorful outline of the light source for a little while? | Your eyes contain cells that chemically react to light. Stimulating them strongly can create temporary lasting imprints because either the cell is depleted of the signalling chemicals relative to other cells (you look at a red image then switch to a white wall - the red cells are less capable to signal than the green and blue ones so that portion of your vision looks more anti-red) or the cells continue to fire since they are so strongly stimulated (you close your eyes and see bright outlines). | 70 | 120 |
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What is special about sunlight versus artificial light that plants need it? | If all light is just photons, and plants convert photons into sugar through photosynthesis then why do plants die when placed indoors even if given enough artificial light? | Plants operate best on certain wavelengths of light, and not all light is the right wavelength for them. There is also that people tend to vastly underestimate what is "enough light" for a plant to grow properly. Without special high output lights, indoor lighting is not actually bright enough for most species of plants. Plants can absolutely be grown with artificial light, you just need to make sure there actually is enough and that it's light they can efficiently make use of. | 79 | 45 |
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