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CMV: The words 'islamphobe' or 'islamphobia' are now thrown around too easily such that they lost meaning | Definition of islamphobe on google: dislike of or prejudice against Islam or Muslims, especially as a political force.
My position is that it is OK to criticize Islam (aka the religion), but it is NOT ok to criticize the Muslim people as people.
For example, I can show why the belief that Mohammad rose to heaven on a winged horse is ridiculous, or why Mohammad was a pedophile for marrying a 9-year old (or 12-year old, according to other historical sources). Or I can argue why Islam holds back society. Or I can simply argue how there is just no valid evidence for any of the supernatural claims of Islam in general. All of this, to me, is perfectly valid things to say and is certainly NOT being rude or being an 'islamphobe' to do so.
What is not ok would be to assume, for example, every Muslim hates Western nations and support ISIS. Or that every Muslim is a terrorist. Or that every Muslim wants to suppress women rights.
But apparently many ppl don't agree, and think ANY FORM OF BASHING of Islam is automatically wrong. | Your arguments may be valid, but most people are not critiquing Islam for the sake of academic merit or correctness. Most people critique Islam for the purpose of generalizing Muslims as being undesirable people for belonging to the religion, which is a jerk move. | 17 | 40 |
ELI5: What in the molecular workings of plastic makes it turn yellow after a long time? | I have noticed in older houses lots of plastic that used to be white turns ye yellow. Why is that? | 1. Most plastics are polymers, aka they're made of extremely long repeating chain molecules linked together.
2. Sunlight has enough energy to break chemical bonds over time, and will eventually break these chains into shorter fragments, and break bonds between different chains too.
3. This one's hard to simplify. The property of "being coloured" comes from how a material's electrons are laid out and how they're able to move around. Basically there's a "sweet spot" of molecule size/length that's good at absorbing visible wavelengths of light. When some colours get absorbed, the object appears coloured since not all colours of light are reflected to your eyes any more.
Putting it together: Over time, the light breaks down the plastic until its polymer chains are short enough that they start absorbing light and appear coloured.
Related to this, for plastics that are initially transparent: the sun breaking down the plastic at a molecular level also causes "disorder" or just general damage throughout the material. What was once a more neatly packed array becomes fragmented and leads to more light being "scattered" rather than reflected or passed through. That's why clear plastics also go opaque as well as discolouring. | 41 | 58 |
Why does the Delorean have flame trails when it hits 88 mph? | As I understand it, the sonic-boom type effect is the temporal barrier being broken, but what about the flame trails? | Relevant points to consider when answering:
* The flame trails exist **after** the DeLorean has disappeared through time, not before.
* The flame trails even occur when flying through the air.
* The flame trails persist on the ground, i.e. something has literally set the asphalt on fire (or something flammable has been spread across the ground). The trails also seem to have at least some persistence in the air, i.e. they don't immediately waft away like most gases would.
| 14 | 25 |
ELI5: Why is it still a challenge for some countries to build ICBMs while US/USSR could already do it in the 50's? | ICBM technology requires an extremely advanced research and development basis in aerospace engineering and rocket science. Which in turn requires strong institutions specializing in physics and mathematical research.
But that strong research basis will only get you the theory and design because engineering a rocket requires that your country also have a manufacturing sector that includes the skillful production of precision instrumentation, specialized machinery, advanced application of metallurgy, and chemical processing for fuel and lubricants. Which, by the way, requires even more knowledge and research to implement because all those necessary requirements would take decades to develop.
But that's not all, guidance systems require that your country also have an advanced electronics industry capable of producing components that can withstand conditions normal electrical equipment would simply break down mid trajectory.
Now, you can shortcut this extremely complicated process by buying and importing all those things that are necessary for the development of ICBMs, which is what North Korea did. But that still doesn't take into account the expertise and infrastructure you need to test and produce a viable system.
The ICBM still needs a warhead which has its own development process, but actually relatively easier than producing the delivery system.
So the countries that developed ICBMs are countries that had the foundation prior to their goal of producing ICBMs. The United States, and the Soviet Union, already had a strong industrial base and scientific research community to lean on to develop their ICBMs, not to mention that they both were able to acquire expertise and know-how by importing former Nazi scientists and capturing the research the Nazi regime made in developing their own rocket technology. Germany was (and still is) a great scientific and industrial center.
Many countries even developed and advanced economies, lack ALL the components required to develop ICBMs. Even developed countries that do have the necessary factors to develop ICBMs choose not do so because the allocation of resources toward the goal of producing an ICBM would be economically ruinous for their country and result in major hyperinflation and suffering. It would take years and the resources put into developing an ICBM would be resources wouldn't pay for a national healthcare system, public education, retirement payments, etc. So many countries simply ally with the US and sign treaties asking to be under the protection of their ICBM program, for example, NATO. And those countries also agree not to pursue technology like that under international treaties at the behest of the superpowers. | 38 | 29 |
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ELI5: How do monarch butterflies migrate through multiple generations, considering that one of them can only make it part of the way? | Genetically learned traits. Basically they've been doing it so long it's become ingrained in their core. They even fly around an obsticle (can't remeber if it was a mountain or lake) that's not even there any more! A million (or whatever) years ago this feature of the Earth went away, but the butterflies still circle where it once was. | 49 | 151 |
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CMV: Innocent until proven guilty should always be upheld, especially regarding the recent trend in sexual harassment accusations. | First of all I want to clarify that sexual harassment is wrong and should be prosecuted.
But recently, the way the media and the public react to those accusations is wrong. Everyone immediately turns away from the accused, and treats them as guilty with out trial.
I believe that those accusations should not be made public, but handled by the authorities, similarly to what Terry Crews has done recently. The public backlash is too severe and can hurt the accused even if they're not found guilty. There have already been cases of people falsely accusing people of harassment. This should never happen, but it does because of the way these accusations are currently handled. | Innocent until proven guilty applies to the law. As it stands, these men are not literally on trial for any actual crimes. In fact, they likely never will be, but that's not the point.
We, as a society, are not lawyers. There probably never *will* be a trial, or tangible evidence, but we are welcome to believe what we want to believe. | 28 | 46 |
ELI5: Why did it take so long until radioactivity was discovered | In my country, uraninite was mined alongside silver at least since the 15 century, useless at the time. It is kind of strange to me that nobody noticed anything "weird" about it for such a long time (or did they?)
Is the concentration too small in this form to have effect? Even if they piled it up in junk heaps along with everything that wasn't silver? Or were the people working with it already too ill to notice anything extra going on (mining was not a particularly safe or healthy occupation for a very long time)? Or did they actually know something is weird about it? After all, what did tip off Marie Curie that there's something odd about this mineral? | So the thing about radiation, outside of the most extremely high concentrations it isn't going do much of anything immediately where you can really easily see cause and effect. Those super high concentrations don't exist naturally, they have to be refined into that.
Even in modern times after something like the chernobyl disaster only 31 people directly died from it, the rest of the effects are long term increases in things like cancer rates which we can really only figure out because of statistics and having a huge sample size. | 54 | 38 |
How can I quickly and accurately verify a science or history book is not making claims debunked by the academic community? | I have recently taken an interest into listening to audiobooks focusing on history or areas of science I am not as familiar in to expand my knowledge. I've started to notice many of the reviews are focused less on the accuracy of the books and more on the readers experience and the descriptions/critical reviews are often hand picked to sell the book, which has made it hard to differentiate between the popscience books and academically respected books (especially in the fields that are easily politicized or monetized like medicine or neuroscience).
To be honest, I am an embarrassingly gullible person so I am worried about picking books from areas I am unfamiliar in but interested in learning more. This is especially so since I already recognize some of the more obvious self help books disguised as science books in the medicine category. An example that comes to mind is that book "Guns, Germs, and Steel" which has been wildly popular but I have heard misrepresents the facts from communities familiar with the subject material. Is there an easy way to check on the accuracy of the claims of a book? I've tried googling books but it's often reviews done by people as ignorant of the subject matter as I am taking the author at their word that show up on the first page. It's also hard to tell with so many people crying "fake" at things they don't want to hear or actual misinformation being spread as facts.
I don't have a particular field of study or title, I am just trying my hand at educating myself outside of the structure of a university.
I'm from the US with a bachelors degree in Radio Television Film of all things, so I would like to expand my knowledge of various fields of science I may have neglected when I was younger. Any help on how to sort the the noise and find academically approved books would be greatly appreciated by this gullible amateur brushing up on their self educating tools. Thanks in advanced guys. | I'd honestly start by reading intro text books. You can find used old editions on Amazon pretty cheap ( <$10). With that foundation, you will be better equipped to judge what is plausible. Another (easier, but less beneficial in the long run) way would be to google the background of the author. Not the most reliable method, but it can give decent context to whether the person knows their stuff. | 22 | 33 |
ELI5: How can the weather be below freezing AND 100% humidity? | Doesnt the temperature mean that fog can't be "humidity"?
Isn't humidity moisture and doesn't moisture crystallize into a solid form below 32 degrees? | There are two forms of humidity: relative humidity (%) and absolute humidity (grams of water/liter of gas). Something that is at 100% humidity means that it is holding as much water as possible, no matter how little that may be. | 29 | 23 |
CMV: Pulling the lever to save more lives is the right response to the classic "trolley problem". | Firstly, I understand that this has been posted before. However, none of the discussions I've read on other threads have managed to change my view, hence my posting here.
When faced with the trolley problem, when the options are divert the trolley and kill one person, or leave it alone on its tracks and allow 3 people to die - I think we would have a moral obligation to pull the lever and kill the one person. Because the outcome is what's important. In other words, it's better for 3 people to live and one person to die, than 3 people to die and one person to live.
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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!* | The problem with that is that once you establish that people have a positive moral obligation to act in this manner, you are compelled to also accept that you have the same moral obligation in other scenarios. For instance, you have enough organs to save the lives of several other people. Do you also believe that you ought to sacrifice your life in order to donate those organs to other people to save theirs? On net, we lose 1 life but save half a dozen, maybe more. As you say, "the outcome is what's important" so it shouldn't matter that you die, as long as we save more than 1 other person. And, that's probably a really simple problem. There are innumerable other problems with utilitarian calculations that force you into bizarre and untenable situations. | 30 | 18 |
What is the Difference Between Deduction and Induction? | Hi,
I really can't distinguish between **Deduction**, **Induction**, and **Inference**. I guess inference is same is deduction (right?) and I do know what **deduction** is, but what's its difference from **induction**?
Also are there any differences between **Probability** and **Possibility**?
Thanks in advance | Deductive arguments attempt to show that the conclusion must follow from true premises. If it is successful, the argument is valid. If it is unsuccessful, the argument is invalid. If it is successful and the premises are true, the argument is sound.
**Deductively Valid Argument:**
If it is raining, the grass is wet.
It is raining.
Therefore, the grass is wet.
**Deductively Invalid Argument**
If it is raining, the grass is wet.
The grass is wet.
Therefore, it is raining.
Inductive arguments attempt to support (but not guarantee) the truth of the conclusion. If they are successful, they are strong. If the are unsuccessful, they are weak. Unlike deductive arguments, it's possible for an inductive argument to have true premises and a false conclusion while still being a good, i.e., strong, argument.
**Inductively Strong Argument**
99.3% of bus drivers do not have a PhD in Economics.
Jim is a bus driver.
Therefore, Jim does not have a PhD in economics.
**Inductively Weak Argument**
Many Italians live with their parents until they 28 years old.
Pablo is a 22-year-old Italian
Therefore, Pablo lives with his parents.
Arguments which rely on probability are usually in the inductive camp. Arguments which rely on possibility are usually in the modal logic camp. These are different things.
| 32 | 24 |
ELI5: Why do different colors have a different shade of gray when saturation is removed? | Like when I'm in photoshop and turn the picture to grayscale or remove the saturation.
Red shades will always be darker than yellow ones for example.
Why is that? | On the surface it seems like all three colors(red, green, and blue) should be weighted equally because that's what the pixel is made of; but it turns out that gives you a really crappy looking grayscale image.
Your eye is far more sensitive to green light than red or blue, and still more senstive to red than blue. When the computer converts from RGB to grayscale it will give far more weight to the green value than the red which means 0,255,0(green) will end up being far brighter than 255,0,0(red) or 0,0,255(blue). Since yellow has a green component it will end up being fairly bright. | 11 | 16 |
[Stephen King] Do any of the books make big news on a national or international level? | Some books could be easily covered up, but some seem like a big deal that would be covered on national or even international news. Do the characters of one book know of the events of another book? | Books like The Mist and The Stand obviously do, but the others are hard to answer.
IT doesn’t make national news, because in 11/22/63 the protagonist visits Derry and meets two of the characters from IT (and even kind of vibes on the monster). Given how exhaustively that character would have researched the local history if any of the major events from IT had made national, or even regional, news he likely would have mentioned it. Instead we just get his vague impression that the town is “sick.” | 38 | 36 |
ELI5: Answer an ELI5 FAQ- Why do Coca Cola, McDonalds, and other national companies still advertise? | Help ELI5 explain this common question so that we can redirect future posters here.
Please also explain why companies that do not sell general consumer goods advertise, such as Boeing, Cisco and BASF
https://www.reddit.com/r/explainlikeimfive/search?q=still+advertise&restrict_sr=on&sort=relevance&t=all | There are many reasons for advertizing by non-retail customers. Often called "image advertizing", these ads are designed to influence public opinion of the company. Public opinion influences the company in many situations, including:
* Hiring, potential employees send resumes out to company they perceive as desirable places to work.
* Lobbying, favorable public perception adds clout to the company's lobbying efforts. Particularly the threat that the popular company might take a public position for or against some legislation.
* Community relations, advertizing activities that improve relationships with the community makes those "good deeds" more well known. Should something unfortunate happen, this store of good will may reduce the cost of mitigation.
* Inventor relations, showing that the company makes uniquely profitable products, even if they aren't sold retail, signals investors that the company is a good investment.
| 24 | 22 |
ELI5: Why are rings easier to get on than they are to get off a finger? | 2 reasons for this:
1. The fingers are generally wider near the knuckles than at the fingertips.
2. If you stroke one of your fingers with another from nail to knuckles, you will find that skin has more resistance when you're moving knuckle to fingertips than vice versa, mainly because there's more skin near the knuckles than the fingertips so it kind of bunches up and resists more than going the opposite direction. Credit to /u/super_ag for the more accurate reason. | 26 | 52 |
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ELI5: Why does the Japanese language have English loan words for things they already have words for? | Words like "relax" (rirakkusu) and "hose" (hosu) seem like something that would have existed before contact with English-speaking people. | The words often have slightly different connotations. For example, the English loan word *kyanseru* (cancel) is an informal, modern-sounding way to talk about canceling something. If you were talking about canceling a contract or other more formal arrangement, you would likely instead use the Chinese loan word *kaiyaku*. And if you wanted to talk about canceling in a more general or abstract sense, like taking back your words, you might instead use the native Japanese word *torikesi*.
Japanese is not unique in this regard. English has many French and Latin loan words for terms that already had native semi-equivalents: pain/hurt, rage/anger, response/answer, prior/before, commence/begin, creed/belief, abdomen/belly, corpse/body, fraternal/brotherly, construct/build, etc. | 75 | 22 |
ELI5: What is fed to people in a coma? | Is it blended every day food or similar to meal replacement shakes? If so does this include fruits and vegetables or are all essential nutrients provided though supplementation? | It's a special liquid formula that contains the right amount of calories, protein, and essential nutrients that can be adjusted depending on the specific needs of the patient. It's doesn't contain any actual food but it does have all the nutrients and calories we need from eating food. | 32 | 29 |
ELI5: Why do malls and businesses not have peaked roofs like you see on houses? | I remember hearing about a store collapsing from too much snow collecting on the roof. Is there a reason not to have a peaked roof to prevent this? | Flat roofing is cheaper to build, is accessible (you can go up on it and do stuff up there more easily, including maintenance and are unlikely to fall), and you can add another floor more easily if you want to.
Providing you have a decent membrane on there and it doesn't need much maintenance, it will be cheaper in the longer run than a pitched roof, and gives you more options. | 13 | 17 |
CMV: I don't think I should personally make changes to my life to fight climate change when multi billion dollar companies couldn't care less. | Why should I stop using my car and pay multiple times more to use exorbitant trains?
Why should I stop eating meat while people like Jeff Bezos are blasting off into space?
Why should I stop flying when cruise ships are out and about pumping more CO2 into the atmosphere than thousands of cars combined?
I'm not a climate change denier, I care about the climate. But I'm not going to significantly alter my life when these companies get away with what they're doing.
I think the whole backlash against climate change is most often not out of outright denial, but rather working class people are sick of being lectured by champagne socialists to make changes they often can't even afford to, while the people lecturing them wizz around in private jets to attend their next climate conference. | 1. If everyone thinks as you do, then change is not possible.
2. Helping *a little bit* is better than no help at all.
3. Reducing your meat consumption and walking or using public transportation when possible will neither change nor impact your life in any significant way. | 1,596 | 4,754 |
What does not emit electromagnetic radiation? | My remote sensing textbook states "With the exception of objects at absolute zero, all objects emit electromagnetic radiation."
I understand that an object doesn't have to emit it's own radiation, it can reflect another objects radiation.
So what are the processes that cause electromagnetic radiation to be emitted?
Wha are objects that do not emit their own radiation? | Objects are made of atoms and atoms are made of charged particles (nuclei and electrons). Charged particles emit EM radiation when they are accelerated. All objects at a nonzero temperature T undergo some form of thermal motion and these random vibrations involve varying velocity and thus accelerations. Therefore all objects will emit a "baseline" spectrum due to thermal motion called a blackbody spectrum.
A blackbody (body that doesn't emit or reflect anything else other than the blackbody radiation) has a spectrum described by the Planck distribution, which is universal, depending only on the temperature and not on the details of the body or the material.
For temperatures above a few hundred degrees °C, the Planckian spectrum is significant in the visible range of wavelength and so bodies hotter than that glow with a specific colour and intensity, this is just incandescence.
At room temperature, most of the blackbody radiation is emitted in the far infrared region, therefore named thermal infrared, and this radiation is visible only through (relatively expensive) thermal cameras. | 61 | 157 |
Is there an ancient African philosophy analogous to ancient European or ancient Asian philosophies? | Discussing comparative philosophy the terms, "ancient European philosophy" and "ancient Asian philosophy" were being thrown around until somebody asked, "Is there an ancient African philosophy?"
The presenter talked about the Middle East and ancient Egypt (technically part of Africa), which led me to think that perhaps there isn't a particularly African brand of ancient philosophy, there are just ancient philosophies that took place in Africa, usually Mediterranean countries near Europe and Asia.
Is that mostly correct? Wildly incorrect?
If someone were interested in reading ancient African thinkers other than North Africa, where would you suggest they start? | A few of Greek Historians (Philostratus and Heliodorus) record a lot of the teachings of the "gymnosophists" (which basically function as the proto-philosophy of both the pre-Socratics and post-Alexandrian philosophy) coming into Greece as coming from Ethiopian priests. In the same way, Plato confidently tells us most of his philosophical innovations can be traced back to Egypt.
That said, there's not much documentation simply because there's not much documentation of the period in general, a lot of the gymnosophists preferred to spread their teaching only by word-of-mouth among dedicated students anyways, and the Greek historians don't always take tremendous interest in sorting out the different strains in the philosophy of the gymnosophists. | 22 | 32 |
ELI5: Why can some animals be domesticated, while others can’t be? | I saw a video of a “pet” raccoon living in somebody’s house. It was cute. I started looking things up about how raccoons become domesticated. All of the literature said it has never been done, and probably can’t be done. No explanation of why. | In guns, germs and steel there are six criteria for domestication.
1. The animal needs to be able to eat a variety of different things and be willing to live of human scraps. Even better if they can eat foods we can't like grass.
2. They must grow up fast or at least faster than humans. This is why despite Asian elephants being tamed for 3000 years they arent considered domesticated. We haven't been able to selectively breed them
3. Animals must be willing to breed in close quarters of captivity. This is why pandas and antelopes are a bad candidate for domestication.
4. The animals have to be pleasant in nature. An animal that is ill-tempered or unpredictable is dangerous.
5. They also need to be calm and not scared/skittish. Because they are hard to control as well.
6. Animals need to be able to see humans as their master so a social hierarchy is important.
Even though some individual zebras have been tamed the species is hard to domesticate because of their temperament.
We have also tried to tame or domesticate great white sharks but they will die in captivity. The longest one has been held has been 16 days. | 25 | 21 |
Novice programmer, what paths should I take and what should I avoid when looking to have a coding career? | I've been learning coding for about a month and a half now, which I was drawn to because 1) it's a skill I hear is in demand, 2) it's a skill you don't have to have a formal qualification in to get a job, 3) it's a skill that can be learnt from home, for free, in your free time. Specifically I've gone over the very basics of Python, as well as some basic data analysis lessons in Jupyter with pandas, covering data cleaning, tables, graphs etc. One thing I've heard anecdotally a few times across some of the programming related subreddits is of people having no experience in coding at all, then after a year of teaching themselves manage to land a job in it. Is this typical or are these outliers? What factors determine going from novice to employed so quickly?
A concern I have about pursuing a career in coding is that I don't want to end up following a path that becomes obsolete in a couple of years time, see [https://twitter.com/sharifshameem/status/1282676454690451457](https://twitter.com/sharifshameem/status/1282676454690451457)
This comes after I was under the impression that coding was a profession that would be safe from automation for some time. For those with experience, who understand the industry and where it is heading, which sort of paths is it best to go in to have a career and I won't end up learning something that is no longer employable in a short amount of time? Or if that's a stupidly wide net to be casting, what paths/specialisations do I want to avoid? Am I better off going "wide", and learning several different programming languages and tools, or going "deep" and sticking to python and data analysis to become really good at it and ignoring everything else? | It’s like any profession - you don’t NEED a formal education, but the chances of you getting a satisfying job are actually quite low without one.
There are lots of people from overseas and in a situation similar to yours, who are attracted by the lifestyle and money, with low barriers to entry.
You hear the success stories because they are exceptional.
Now, coding is like construction: there are lots of tools and techniques - and every company has their preferred set of them. The important point is not actually the tools you know, it’s how deeply you understand the underlying concepts - avoiding bugs and . It’s also how fast you can learn and solve unexpected problems.
So, how does it sound now? Just like construction, start with a job that’s building simple things in a high quality way - like setting up websites, or writing macros for Excel sheets, or using public APIs to access data. The goal is to build high quality outcomes. Your question about deep vs wide “skills” is something you’ll find comes as a consequence of doing your job well. They aren’t goals that directly lead to success in your career. | 15 | 32 |
ELI5: How are pilots able to make flights significantly shorter? | A flight I’ve taken many times usually takes around 3 hours. I just took the same flight and the pilot was able to get us there in just about 2 hours. My return flight we were 45 min early. How?? | There’s a few ways: 1. Different altitudes have different winds. 2. Commercial aircraft rarely fly at max speed, so the can literally fly faster (at the expense of increased fuel flow).
The key point the OP needs to know though is that it’s not up to the pilot. The airlines carefully manage flight plans (including speed etc) to ensure the overall schedule in the most cost effective manner. Sometimes it benefits the passenger😏 | 174 | 142 |
If you had a national UBI policy how do you prevent landlords, energy companies, insurance etc from raising costs to capture some of that Income? | I keep hearing about Universal Basic Income, and how universally give folks a set amount would help.deal with inequality etc. But wouldnt landlords, energy companies and others that have non discretionary costs simply up their prices /rates to capture some of that money, negating the inequality purpose of UBI? | While landlords especially could raise their rates to capture some of the UBI income, the landlords whom don't raise their rates would have an advantage against those who did, and could more easily find tenents. Those who do raise their rates will need to compete with landlords who have better properties, but chose not to raise their rates. And since rent in the area has been raised, there is more incentive to build housing, which will also drive down prices.
If a $1000/mo UBI is passed, landlords will not all raise their rates by $1000/mo. Rent will increase, but by some amount less than $1000/mo.
Insurance will be handled similarly, but since they can more easily take on new customers, they will be even less able to raise their insurance rates.
This is, of course, excepting the possibility of all the landlords in an area getting together and deciding to raise all their rates at once, while also ensuring that no other housing will be built. | 22 | 57 |
ELI5 How game developers write and design games for the XBOX 360, PS3, and PC simultaneously? | I always wondered how a studio can write a game for the XBox 360, PC, and PS3 at the same time and have all versions come out identical. Do they just make one version of it? Are there different teams that work on different consoles? How's it work? Keep in mind please that I know absolutely nothing about writing code or designing games. | One of the big ideas in programming is *abstraction*. Basically, this means hiding away as many details as you can about things, in order to get a higher level view of it. Using a web browser is a good example of abstraction: In order to view a web page, you do not need to know anything about how the internet works. You just give the browser an address, and it does all of the work of finding the right server, requesting the page, and then rendering the page once it comes in. The details of how it does this are not important to you. In fact, Mozilla or Google could change how it works entirely, and as long as the browser still gets you your page, you don't really have to care.
People writing games try to do the same thing. They try to add abstractions to their code, so that the details of what platform they're running on end up mattering very little. Inevitably there will have to be some platform specific code. But, in a well written application, this portion will be relatively small. | 129 | 260 |
Is it okay to give a small gift to my professor? | I’m transferring this fall. And I wanted to give a small gift to one of my former professors who took me under his wing and helped me fall in love with English and Journalism. I took 3 of his classes. He has helped me find the schools that would fit me best. Because of him, I became an English major.
I wanted to gift him a box of Nutter Butters (something that he always brought to class and snacked on) and also some nice carabiners (because he uses them a key chains and for outdoor activities), or if not the carabiners, an REI gift card. I will also write a little note thanking him.
Anyways, is this too much? I just wanted to thank him for being so kind to me, taking me under his wing, and ultimately allowing me to fall in love with English. Thanks :) | Be sure that you have your final grade for any of their classes before doing so, and don't be shocked if they decline any part of the gift. Many professors have strong policies against conflicts of interest. Some schools also have policies on gift giving. It's a nice gesture, though. | 104 | 109 |
CMV: Putting aside cost, tax policies, implentation, etc. I believe Sanders' free college proposal is fixing a symptom, not the problem, of education in America. We should be focusing on fixing K-12, not making college free. | I want to avoid the discussion of how free college would be achieved. For the case of this argument free college is obtainable, paid for, and easily implemented.
A college degree means less than it ever has [Source](http://www.forbes.com/sites/georgeleef/2014/04/21/college-degrees-arent-becoming-more-valuable-their-glut-confines-people-without-them-to-a-shrinking-low-pay-sector-of-the-market/#7d6a14e371da). The current trend is that a bachelor's degree is becoming the new high school degree.
Sanders, and those who support him, believe the solution to our education problem and job problem is to make public universities free.
I believe this is fixing the symptom of our K-12 education process rather than fixing the fundamental problem that is our uncompetitive K-12 system.
I believe the money that would be funneled into making college free would be better diverted to fixing K-12.
College *is not* for everyone. As a recent college grad, I watched plenty of people come to, and drop out, of college after being pressured into going because "college is important."
College is important, but it truly isn't for everyone. Making college free would further force people who don't belong in college going to college. Instead we should be promoting trade schools, apprenticships and fixing our broken K-12 system.
I firmly believe free college would devolve into schooling being quasi-mandatory for 16 years rather than the current 12.
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> *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | I agree with you that the solution doesn't lie in "free college for everyone", but improving K-12 education doesn't solve the problem either. There are two benefits of college education. Increasing skillset, making you more productive, and competitive advantage against other job applicants.
The fundamental problem, what drives people to college who "shouldn't go", is employment. If you want to have a respectable living wage with a decent standard of living, you pretty much need to go to college. (There are some industries that are overlooked and underserved like the trades, and we should encourage people to get into them, but that isn't going to solve the entire problem). 30 years ago, manufacturing was strong, people could graduate from highschool, start working immediately, and expect a decent living wage and some opportunities for advancement. Blue collar work like manufacturing is a fraction of what it used to be in the US, what with outsourcing and automation.
No matter how good the K-12 system is, it doesn't bring those jobs back. There are two facets to this, worker productivity adding value to the economy, and competition, a higher qualified-worker-to-position ratio leads to lower wages. Improving K-12 education could improve workers productivity, but it won't change the competitive advantage aspect that drives people into the "pay to play" system. | 83 | 659 |
ELI5: Why does salt water naturally exist on Earth and why is there so much more of it than regular fresh water? | Salts are really common chemical compounds.
Water is a very good solvent.
It's not really surprising that large amounts of minerals end up in solution in large scale water reservoirs. It's just in lakes and rivers, the water moves on before it has a chance to get too salty.
Except when the lake doesn't flow anywhere and you get the dead sea. | 61 | 92 |
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ELI5:Why do some (Cessna 172 for example) planes need a fuel mixture which is adjusted by the pilot, but a cars fuel air mixture is automatic? | Combustion engines rely on having the correct air to fuel mixture ratio.
The air pressure (and therefore Oxygen amount) at ground level is fairly static, so maintaining the correct air/fuel mixture ratio manually is unneeded.
However, at higher and higher altitudes, the air pressure , and therefore oxygen content lowers, and therefore in order to maintain the correct ratio of air to fuel for combustion *at different altitudes* requires the pilot to be able to set this mixture ratio manually. | 55 | 226 |
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ELI5: What exactly are headaches and what causes them? | There are many types of headaches with a variety of causes including tension headaches, cluster headaches, sinus headaches, and migraines. A lot of headaches are caused by inflammation of nerves, sinuses, or other tissues in the brain and neck. Sore/pulled muscles can cause headaches. Frequent migraines are less understood, and are often treated without knowing why the treatments work. Example- treating migraines with anti-seizure meds.
Source: has chronic migraines, not a doctor | 12 | 18 |
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What is the difference between a real and virtual particle, and why does that difference matter? | Pun not intentional | A real particle is a thing you can measure. A virtual particle is something which looks a particle if you represent perturbative calculations by feynman diagrams and has basically nothing to do with an actual particle. | 110 | 653 |
Can we cut wasteful spending by giving government agencies incentives for having a budget surplus? | I'm not sure if this is the correct place to post this, if it isn't, I'll take it down. Bare in mind I'm not an economist, it's just a random thought. So here goes:
I've worked for a private company that is a supplier to different agencies of my local government. It's no surprise that prices of the products are way higher than the market since government contracts are essentially money printers for private companies.
Besides that, an agency/ministry will deliberately blow through their budget at the end of the year. The reason for doing so is avoid budget cuts for the next year.
The way funding is allocated to these government agencies incentives over spending and would increase government debt.
My idea for this goes someting like this:
At the end of the year, budget surplus will be tallied and the agency with the highest surplus will receive priority funding for the next year as well as a budget increase. Those that don't have a surplus will undergo an audit for overspending.
Half the surplus funds will be collected to put back into the treasury and will be given back on the next budget allocation.
Will someting like this work? | Public choice theory is the study of incentives by government agencies, politicians and bureaucrats. The general idea is that the incentives of those in positions of government don’t align directly with the hypothetical benevolent dictator, and choices are guided by self enrichment or other objectives.
In one model by Niskanden, government agencies seek to maximize budgets, not the social welfare of those affected. It sounds like you are implicitly taking this incentive on through a budget surplus incentive.
Sounds like the obvious perversion of incentives here are to maximize surplus by reducing expenditures as much as possible without the agency being penalized for that. So what is to stop a department like housing or education from cutting as much discretionary funding as possible in order to maximize next year’s budget? In general, if an agency had the ability to cut services in such a way that was socially desirable, why would we then want to increase those budgets in subsequent years?
At the same time, why not audit all agencies? Oh, yeah because those auditors are also rational actors in the game. So we then need to audit the auditors. But who audits them? It’s auditors all the way down. Until we reach the turtle shell. | 53 | 71 |
ELI5: what exactly is the determinant of a matrix calculating, and why does it end up being so significant/useful in other matrix calculations? | I'll focus on 3 x 3 matrices.
Take any 3D shape. Something that's asymetrical, like a sculpture of Vincent Van Gogh's head. Or anything else, it doesn't matter, but it should have a finite volume V. (and not zero volume, like a flat plane). Think of your 3D shape as sitting in an x,y,z coordinate system. There are infinitely many points in your shape and each of those points P is described by a vector that goes from (0,0,0) to P. So you have infinitely many vectors that describe your shape.
Now suppose we have a matrix M. We can think of M as transforming vectors. Take a vector v and M\*v is some other vector (or maybe the same vector!).
We're going to take every vector that's describing your shape and transform each of them with M. The end result will be another shape. How different it is will depend a lot on M, but it can be any combination of the following: your original shape rotated about some axis; your original shape scaled up or down in size; a mirror image of your original shape; your original shape skewed, as if it were made out of clay and your smushed/stretched it uniformly along some combination of directions.
The volume of your transformed shape is likely different than it was originally. The factor by which the volume changed is the determinant of M. That is,
New Volume = |det A| \* Old Volume.
I used absolute value on the determinant there because volume ought to be positive and the determinant can be negative. A negative determinant has a straightforward interpretation: it means the transformation of your shape involved taking a mirror image. Like Vincent van Gogh's missing ear switching sides.
With this volume-based interpretation of determinants we can quickly make some inferences about determinants that are pretty hard to perceive just from the definition of determinants. For one, a zero determinant must mean the transformation squished your shape to something with zero volume -- a flat plane, or a line, or a point. So any matrix that "projects" down to a plane or a line or a point must have zero determinant. Also we can infer if the transformation by M only rotated your shape without altering it otherwise, then the determinant of M should be 1, since the volume is the same. Likewise, a purely mirror-image transformation, or a mirror-image combined with a rotation, ought to have determinant -1. Also we can infer the important rule for determinants, that if K and M are both matrices, then det(K\*M) = det(K)\*det(M). I'll leave that for you to reason through. | 13 | 18 |
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I think that scholarships specifically designated for a certain race are racist. CMV. | There are a lot of scholarships out there that are only for African-Americans or only for people of Native American descent.. As a Caucasian female, I fail to see why this doesn't count as racism. If someone were to designate a scholarship for a Caucasian person, it would be immediately declared as racist. Just like I don't believe that someone's skin color or ethnic descent automatically makes them inferior to others, I also don't think that being a certain skin color/ethnic background makes it okay to separate someone out for positive benefits. | The purpose of scholarships targeted at these minorities is to offset other disadvantages they already face. For historical reasons they are more likely to come from poorer families and have greater difficulties obtaining a college education.
One might ask why they are more deserving of a scholarship than someone from a poor white family and on the level of individuals this is hard to justify. However one must see the bigger picture and understand the problem this is trying to solve. The marginalisation of a particular group of society is not healthy for that society. Once a group becomes disenfranchised it can lead to social unrest and violence as has happened in the past. For this reason it is desirable to integrate minorities into society and attempt to give them an equal economic and social standing as other groups in society. Targeted scholarships are just one tool used to achieve this. | 115 | 419 |
What value do cryptocurrency investors add to society? | I guess same goes to stock investors as well. My idea of an economy is you produce goods/services for society and get rewarded with currency, which you can then spend on good/services that other people produce. You can only take as much value out of the economy as you put in.
But this must not be correct because that very simplistic theory breaks down when it comes to investing. When someone makes a million dollars off dogecoin, they didn’t create a million dollars of goods/services for the economy. So why should they be able to take a million dollars of value away? All they did was hold an asset that appreciated tremendously, but where is the value created?
My knowledge of economics is very limited so any explanation of why my simple economic theory is incorrect would be appreciated. | Stock investors are investing in companies that theoretically create value. Capital is aggregated through investment to make things possible that would be otherwise impossible for most people not named Jeff Bezos or Elon Musk. They obviously hope that as their underlying firm creates more and more value that their ownership increases in value. This is a very important aspect of an advanced economy.
Crypto “investors” on the other hand are not investing in anything of inherent or intrinsic value but rather they’re speculating that someone will pay more one day despite the underlying “asset” remaining inert and unproductive. | 15 | 37 |
What determines if two plants can be hybridized or not? e.g. can I combine an avocado tree and a strawberry plant? | Genes determine. So it is the same thing about when two animals evolve different enough to no longer interbreed. Humans have 23 chromosomes, so we can only breed with other things that also have 23 chromosomes and even further only if those 23 are pretty close to ours. Even if the DNA recombines, it can code for nonviable traits (like missing lungs or whatever).
Same thing for plants. First they have to have the same number of chromosomes, then those chromosomes have to be similar enough to recombine and still have enough basics to make a viable plant, then seeds have to have DNA that can code for propagation of the new plant. It is actually very difficult to find plants that can crossbreed, as in general they have to survive being exposed to lots of different pollen while only propagating with the correct pollen (or whatever the equivalent is for the particular plant). | 10 | 20 |
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ELI5: Why when you evaporate coffee and store the steam until it becomes liquid again, the liquid no longer has the color of coffee? | I did this experiment one day because I was curious, sorry if it's a stupid question | Evaporating water, collecting the steam, and condensing it back into water is known as distillation. By doing this with coffee, you are essentially just separating the coffee from the water - the coffee stays in the cup and the water turns into steam (that you collect and condense back into water). Because the water no longer has the coffee in it, it goes back to being clear. | 352 | 261 |
ELI5: How can plants survive hydroponically, but die from over watering in different environments? | Over watering plants can kill them in several ways. It can "drown" roots and deprive them of oxygen. It can interfere with uptake of certain nutrients, or it can promote fungal growth which can infect plants.
Hydroponic setups aerate the water to keep it oxygenated, and typically have some portion of the roots exposed to air. The water has specific nutrient levels in a form the plant can use. Fungi tends to do poorly in these systems because, unlike dirt, there isn't a lot of organic material to consume. That said, not all plants can be grown hydroponically. It's best suited for annual plants that have a short life cycle and doesn't work well for plants with specific soil needs. | 80 | 56 |
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How do so many experimental psychology papers get away with n=15? | I've been reading a lot of papers for my thesis lately and I keep seeing papers (that aren't pilot studies) with sample sizes between 15 and 30. How is that even remotely enough to draw inferences from? Shouldn't there be problems with random noise not canceling itself out due to the small sample size? | The necessary sample size depends on what you're trying to estimate, and with what precision. Psychology has a problem with low power in general, but it's hard to speak generally about "getting away with n=15" without specifying what kind of experiment we're talking about. There are many results in psychology that are perfectly replicable with a sample that small, and many experiment that should probably be conducted with much larger samples. | 60 | 37 |
How does brushing your teeth clean your mouth, and has the invention of toothbrushes affected bacterial evolution? | Toothbrushes mechanically helps in cleaning teeth by scrubbing off the dental pellicle layer that has been invaded with bacteria and thus preventing the formation of plaque and its accumulation, getting rid of food particles that remain on the tooth surface that might not be visible to the naked eye. Modern day brushes focus more on being less invasive towards the periodontal tissue (mainly the gums) and being more reliable in consideration to the time and amount of force that the consumer applies during their brushing sessions. Also back then when toothbrushes were not around, people often used alternative ways to brush their teeth (see miswak or teeth cleaning twigs).
In relation to toothpastes and saliva they help in regulating the pH of the mouth that occurs due to by products of carbohydrates fermintation by the bacteria in the mouth, acidic pH increases the rate of demineralization of the dental enamel and limits the mineralization of the dental enamel. Also toothpastes tend to have prophylactic components that aid in the exchange of minerals between the tooth and the oral cavity and some have anti-microbial and others with periodontal-friendly components, but mainly saliva plays an important role in maintaining the oral balance and dictating its hygiene. | 652 | 1,666 |
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Why are random access speeds of flash memory different from their sequential access speeds? | I understand that on rotational disks, sequential reads and writes are faster than random ones because the head is already in place to read sector B after it reads sector A, and moving over to sector Z takes time. But a flash device has no moving parts. Why is reading page A followed by page B faster than reading page A followed by page Z? | There are two primary factors that cause sequential and random access to have different speeds:
* Sequential access allows future activity to be predicted and acted on ahead of time. Future data can be prefetched either in parallel with the current read, or after the read is complete but before the operating system has time to process the response (so it is ready before the next request). This saves time resolving wear-leveling mappings [1] and reading the data from discontinuous blocks if a sequential request is received next. This is similar to why sequential RAM access is a big deal when designing data structures when programming, because reading sequential RAM is extremely fast due to future requests being cached ahead of time.
* An SSD has a maximum buffer size for the amount of data it can read in a single request. Random reads are often smaller than sequential reads in real-world situations. It will take more requests from the operating system to read the same amount of data in smaller segments than in a single large segment because some of the buffer space is wasted (unused) for each request if the random chunks are smaller than the buffer size.
[1] Because flash blocks can only be rewritten a limited number of times, any practical consumer SSD will implement wear leveling. This essentially means that blocks are not contiguously and permanently assigned in the order the operating system sees them in when it reads the disk. The SSD automatically remaps which physical blocks store data to avoid overusing a single block to the point of failure. | 13 | 64 |
[Marvel Universe] Could Tony Stark make a suit out of adamantium? | The way I understand it, adamantium is one of the strongest metals there is. I would assume Tony Stark would want the strongest suit.
Would there be any barriers to him making a suit like this? | Cost and availability for one. Adamantium is very hard to get a hold of, possibly moreso than Vibranium. Also, the fact that once processed Adamantium cools it stays in that shape FOREVER would likely make it less appealing to work with. Making certain parts of the suit, specifically plates that cover the vital organs, from adamantium could be a possibility, but a whole suit would be very tedious to make. Weight is also another factor, and entire suit of armor could weigh as much as a ton and make for some difficulties in movement and flight | 59 | 67 |
ELI5 What is it specifically about substances like mercury and lead that kills you? | I understand something like Carbon Monoxide which physically takes up space that should have oxygen there but what about lead in my blood kills me? Is it a chemical reaction that steals nutrients? Does it puncture blood cells? | Many proteins in your body incorporate atoms/molecules of specific metals like iron, copper, manganese etc. Those metals are crucial to how those proteins function. Heavier metals, like mercury can be put into those proteins by mistake. This means the protein will no longer work. Depending on what the protein does normally, that can cause lots of problems. | 18 | 38 |
[Frozen/Avatar] If Elsa was in the Avatar universe would she be viewed as just a particularly powerful water bender or something else entirely based on her feats? | The main sticking point would be the ability to alter the climate: while water benders can freeze water, they can't simply make it cold, and certainly can't affect things on a national level. Likewise, while benders can animate stuff by moving it, creating living beings is something there is absolutely no precedent for in the ATLA verse.
There'd be more then enough evidence for people to realize that there's something going on here beyond merely a water-bending prodigy. | 61 | 35 |
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ELI5: Does Chinese Herbal Medicine work? | Coming from a family that believe in Chinese herbal medicine, I've been to the Chinese doctor plenty of times. They take a look at you, measure your pulse from your wrist with 2 fingers and just blank out for a few minutes. Then they list out a whole list of problems and prescribe herbs where you boil and drink (I call it Liquid Tar).
My family believes in these practices as it has been practice over a long period of time but there doesn't seem to be a lot of research involved. I've asked my regular family doctor about this practice and he didn't have much to comment on it.
So does Chinese Herbal Medicine work or is it just a Placebo effect?
P.S. I drink the stuff but I don't know if I get better because of it or it's just my body recovering naturally. | Technically, we have to say "it depends", as all actual FDA-approved medicine was once herbal medicine that was studied for active ingredients, and we now know exactly what to extract that produces desired results.
Eg; Your grandma's secret poppyseed bread may always remove pain because it's loaded with "milk of the poppy", aka Opium. Or that jar of mold she spreads on a cracker to cure your food poisoning is incindentally a raw version of penicillin.
More than likely though, it's just placebo, or at least giving you vitamins and nutrients you haven't been eating because you hate your grandmother and don't eat your vegetables like a good boy. | 21 | 16 |
ELI5: Is HIV actually "cured" or not? | There have been a lot of posts in News and Science and stuff like that about new cases of HIV being "functionally cured." What does this mean? Is it a solution, or just a first step towards a solution? Does the treatment work all the time, or occasionally? Do we know yet? | Essentially, with modern treatments, doctors can make sure that if you catch it early and can afford the treatment, they can prevent it from turning into AIDS for a very long time. The "functional cure" stuff is typical media exaggeration, though it does hold some promise for future treatments. What a "functional cure" means is that the severity of the infection stays low even after the treatment is stopped, which is different how the current treatments we use work. What they've found only works for some people, though.
Basically, what doctors can do is keep the amount of HIV in your system low enough that it's very unlikely to turn into AIDS, which is what kills you. HIV used to be a death sentence, but now people who are HIV+ can live long and relatively healthy lives as long as it's detected early and treated. However, the treatments do not get rid of the HIV, so it can still be transferred, and it will come back if you stop taking your medicine.
| 25 | 30 |
ELI5: How do electromagnetic waves such as Bluetooth and cell tower signals pass through walls and other solid objects without any issues? And why are some wavelengths better or worse at it? | What about windows? Windows are essentially solid walls. They can be quick thick, fairly sturdy, and pretty solid. Except light can go through them.
Different materials are transparent to different frequencies of light. For example, stained-glass windows give pretty coloured patters because they are transparent to some colours of light but not others (a red glass panel absorbs frequencies of light that aren't red). Similarly, glass is generally pretty good at blocking (some) ultraviolet light. We don't notice because we can't see it, but if we could see in UV windows would look solid, like walls.
The specific patterns of what frequencies are absorbed by what materials are complicated and we don't want to get into them. But walls are transparent to some frequencies of radio waves (they are also pretty good at bending around corners). Some frequencies may have issues going through walls (like light going through a frosted glass window), but that isn't as much of a problem for radio signals as we don't need to receive the full image (like we do for seeing things), just the signal from one bit.
If you could "see" radio waves anything emitting them (a wireless router, a phone, signal towers) would have a fuzzy glow, and you might be able to see that through walls (kind of like objective markers in some computer games). | 12 | 24 |
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ELI5: how muscle memory works. | I find it fascinating that our fingers can type out words without a keyboard. [5] | When you perform a sequence of one or more actions your brain will begin to associate those actions with each other. There's a saying that goes "Neurons that fire together wire together", which can be interpreted in this context to mean that if you perform two (or more) actions in sequence often enough, the motor neurons responsible for the sequence of actions will become directly connected. Performing the first action will excite the neurons responsible for the second action and make them more likely to 'fire', those excite the neurons responsible for the third action, etc.. Each time you complete this sequence of actions the association between all the neurons involved in completing that sequence grows stronger. Essentially your brain has to work less hard each time you complete that sequence of actions, playing a scale on an instrument for example. This applies for all neurons though, not just motor neurons. Pretty much, if anything reminds you of anything else it is a product of this phenomenon. Your brain associates things when they occur simultaneously or sequentially. | 13 | 31 |
How does 14nm lithography work? | I am wondering what technology the semiconductor industry utilizes to achieve 14nm feature sizes. I searched the web for a while but could only find stuff about Moore's law and why 14nm is great, but nothing tangible about the actual manufacturing process. Would be great if someone could help out!
Edit: I should have made more clear that I'm not interested in a general explanation of lithography but rather in the specifics of the 14nm lithography process, especially how the feature size can be so small. | The two main technologies used are photolithography and electron beam lithography. Generally, you take a silicon wafer, cover it in a material that is resistant to acid but sensitive to light (called a resist), and then expose it to UV light that is shone through a "mask" that lets light shine only on specific spots (this is similar to how cameras focus an image onto film). This induces a chemical change in the resist, such that the exposed parts can be washed away. Then, you expose the whole thing to acid so that the silicon that is not covered in resist gets etched, while the rest of it gets protected. When you remove the resist afterwards, you have a patterned surface. Electron beam lithography is similar, except instead of exposing light you use a beam of electrons, whose path is controlled with electric and magnetic fields, like in an old TV screen. This is higher resolution, but slower.
Another technology is focused ion beam milling, which is sort of like using a pressure washer on a wood deck, except instead of water it's a beam of ionized atoms and instead of grime being blasted away it's the surface atoms. | 23 | 131 |
AskScience AMA Series: I am a leading researcher in the areas of cannabis plant science and plant physiology at Volcani Agriculture Research Center, in Israel. My name is Nirit Bernstein and I am researching cannabis plant sciences, and the best ways to grow medical cannabis, Ask Me Anything! | Medical cannabis is a fast growing field and researchers are delving into the implications of cannabis for medical purposes. Israel hosts one of the world's leading primary research facilities in the area of medical cannabis. I was the first scientist in Israel to study the plant-based science of medical cannabis. I and my team work to advance the academic and applied science of the cannabis plant. Their objective is to develop basic and practical knowledge of secondary metabolism in health-beneficial plants, including cannabis, to contribute to human health and food security, while protecting the environment.
Here are some links to some of my research:
https://www.frontiersin.org/articles/10.3389/fpls.2019.00736/full
https://www.sciencedirect.com/science/article/abs/pii/S092666901831015X
https://www.frontiersin.org/articles/10.3389/fpls.2019.01369/full
I will be available at 12 PM PT (3 PM ET, 19 UT), Ask Me Anything!
Username: /u/Israelinsf | Is there any scientific evidence that flushing plants (feeding only water or decreasing concentration of hydroponic solution) before harvest does anything useful to the final product?
Is there any scientific evidence that leaving plants in total darkness for \~24-72hrs prior to harvest increases cannabinoid concentrations?
Is there any scientific evidence behind the "white ash" test, in which growers seem to believe that cannabis that creates white ash is higher quality or has different mineral content?
Can you speak to the chemical process that is occurring when Cannabis is cured? (e.g. after drying, putting cannabis into air-tight, humidity controlled buckets to allow moisture content to become uniform).
Is there any evidence for supplemental UV lighting to increase cannabinoid concentrations? | 209 | 3,693 |
If each atom has its own spectral lines, how does blackbody radiation cover all possible frecuencies? | I mean,a copper filament emits according to the temperature, but shouldn't it emit only in the "copper spectrum"? | The natural lines are broadened and shifted by different effects. There is Doppler broadening, which refers to the Doppler effect shifting the emission wavelength, because the emitter is moving. Since the particles have a random distribution of speeds, this converts a single spectral line into a Gaussian distribution. Similarly there are interaction effects (like pressure broadening), a particle temporarily shifts its energy levels (and thus its emission light), while close by another particle. These effects average out the narrow spectral lines and you end up with the black body spectrum.
But no object is a true black body radiator. E.g. if you put copper dust into a flame it will look more greenish than an ideal black body. Or look at fireworks, depending on their ingredient they glow in different colors.
TL/TD: It is a statistical effect, averaging out the emission from many particles being in random states. | 12 | 47 |
development economics | So, I'm from a subsaharan country and one thing thats always perplexed me is the literal title of this post — ' development economics' like why does there have to be this need to seperate it, like isnt this entire human science based on developing, its kinda shows how classification systems can hinder knowledge sometimes. Take for example the whole issue of diversity or allyship - its like why do you need a whole group for people who arent racist, that should be the default, or diversity its like you're basically acknowledging that in including people who don't look like you are deviating from some norm... when the norm should be that everyone is included... anyways i digress so development economics... lets talk about it | Undeveloped countries face different problems than developed ones. It makes sense to focus on solving those specific problems. For example, undeveloped countries suffer from major brain drain and poverty traps. These are non issues for developed countries, they would receive no attention without development economists. | 90 | 46 |
[General Supernatural] How far up and down does salt project it's warding power? | It's often seen in movies and stories that a line of salt in a threshold is able to stave off the attacks of supernatural beings, most commonly ghosts and vampires. My question us why don't these creatures, both of which can fly, simply fly up over the line? Or why don't ghosts phase beneath it? Does the salt project an infinite barrier above and below it? | As with most things supernatural, it depends on the intent. Salt across a doorway or window creates a barrier for that doorway or window. If there's another entrance, the creature could enter through that. If the salt forms a circle around an open area, it projects a dome (possibly a sphere going underground) of protection that intersects the ground at the salt. If the ring is smaller than human height, say just a couple feet wide around a person, or is inside a building, it would go from floor to ceiling or an equivalent height to protect whatever it encircles. | 23 | 21 |
ELI5: If cardio is done by raising the heart rate to a high level and sustaining it, why does the heart not constantly improve its health since it never stops beating? | If your heart needs to get stronger it will, that usually means you are in trouble.
Look into the physiological mechanics of most cardiac problems and you will see that most of them aren't the heart muscles failing the body, it's the other way around.
High Blood pressure? Your heart muscle is fine, the problem is that it is working too hard because your body is in bad shape, narrow arteries, obesity, reduced kidney function. It will keep working too, but your arterial walls aren't strong enough to withstand the extra pressure and over time will weaken.
Heart attack? That's a clot or blockage in an artery that starves your heart of oxygen, again it is your body failing your heart muscles.
Low blood pressure? Hormone imbalances mostly. Your heart muscle is normally fine but it keeps getting orders to beat slower and weaker than it is capable of.
Your heart muscle is so amazing compared to the rest of your body that managing your cardiac health is mostly about getting your body closer to the efficiency of your heart to make its job easier.
Cardio expands your blood vessels and improves your circulation. It improves your bodies efficiency at using oxygen and dealing with the by products of anaerobic exercise. It means that your heart gets to take it easy.
An incredibly healthy cardiovascular system is one you are likely to find in people with low excess body weight, active lifestyle, and a good diet that doesn't tax their metabolic systems. This hypothetical person will have a slow heart rate with a strong "beat" but not high blood pressure. Because the body is up to snuff and will have vessels large enough to allow blood to flow easily and a body efficient in using it.
TLDR; You heart is so powerful, efficient, and sexy that it mostly doesn't need to improve, it's your scrub-ass "everything else in your body" that fails your heart. | 766 | 1,056 |
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ELI5:Axiom of Choice | Trying to wrap my head around this concept. If someone could kindly duh it down for me I would be grateful.
Thanks! | A "choice function" is a function which takes as input any one of a collection of sets, and returns some element of that set. So if we have all of the nonempty sets of positive integers, we can define the function "f(S) = the smallest integer in S". For example, f({11,12,13}) = 11, while f({2, 4, 6, 8, ...}) = 2. This is a simple example of a choice function. On the other hand, "f(S) = the largest integer in S" is *not* a valid choice function, since the set of all even positive integers {2,4,6,8, ...} has no largest element, and so f({2,4,6,8...}) would be undefined.
But what if, instead of nonempty sets of positive integers, we're working with nonempty sets of real numbers? If we try to just copy over the same choice function, we'll find "the smallest real number in S" is undefined for a great many sets of real numbers, such as the set of all negative real numbers. Other basic attempts at defining a choice function will similarly run into problems with sufficiently weird sets of real numbers. It's far from clear whether a choice function should exist that is defined on all possible nonempty sets of real numbers.
The axiom of choice states that for *any* collection of nonempty sets (whether nonempty sets of positive integers, nonempty sets of real numbers, or anything else) there always exists at least one choice function. It doesn't say anything about what the function is or how it works - it just says that there *must* be some such function. Surprisingly, this axiom is necessary to resolve several basic-seeming conjectures in set theory (and occasionally other areas). Some of them even feel "obvious", like the statement: given two sets A and B, either they are the same size or one is smaller than the other. Others are deeply counterintuitive, like the Banach-Tarski paradox, which shows that (assuming the axiom of choice) it is possible to cut a sphere into five pieces, move and rotate the pieces, and end up with two spheres identical to the original. Regardless of this latter category, the axiom of choice is generally accepted by mathematicians - though there are still some who reject the axiom of choice or who work with alternate axioms which negate the axiom of choice (the most prominent being the axiom of determinacy). | 10 | 26 |
Why having too many methods in a class is considered bad practice, yet most libraries have classes with dozens, sometimes even hundreds of methods ? | Having many methods in a single class is often a sign that you should divide it up into smaller modules, but that's not always the case. Think of a \`math\` library in most languages, it's likely it will contains dozens of public methods for sin, cos, tan, exponential, etc., plus public constants for pi, e, and so on. It makes sense to put them all together because the only other option would be to divide them up into separate math libraries, perhaps math\_trig and math\_stats and so on.
If it makes sense for them all to be together, then keep them all together. | 38 | 41 |
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[Foundation] What exactly is psychohistory? | It is the study of human interaction. Not at interpersonal levels, but at this if entire societies. As with anything, long term study of a field lets patterns emerge, and those can, if universal enough, be called "laws." Hari Seldon codified this into a branch of mathematics, with a complete internal logic built up around his understanding of these laws. This then allowed him to make predictions about societies, so long as they could not see them themselves. | 15 | 23 |
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[Star Trek] Do Captains have other areas of expertise like flying or engineering or did they spend all of their time at the academy just learning how to "Captain"? | The Command track involves learning enough of more or less everything to be able to fill in without spending the time necessary to specialize. The extra time is instead spent on "captaining" - that is, tactics, leadership skills, history, and so on. | 199 | 255 |
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ELI5: From an evolutionary stance, why are humans bereft of basic defenses:claws, canines, thick hide..And instead runs with diverse body types, no fur, and exposed vital organs? | I accept evolution in its basic and complex forms, but how did humans dominate the jungle without even being able to hold their breath for more than two minutes, or getting a cold after every storm? Research tells me that the subconscious invested more time in perfecting precision and problem solving, but I can't help wonder if there are other theories. | A common misconception about evolution is that it should "improve things".
In reality, though, it doesn't care where our organs are, or what defences we have. It simply favours animals that *learn to survive*. We have evolved from an ancestor of the Great Apes, for which this body structure was well-suited.
Humans have since done a remarkably good job of surviving/reproducing in our relatively-frail form, and so those are the genes that get passed on to the next generation. | 19 | 28 |
ELI5: Why are babies sometimes so unwilling to eat, when it is fundamental for survival? | Failure to thrive is sometimes caused by things that aren't obvious: some babies have acid reflux, some aren't signaling they're hungry in ways the parents pick up on, some have other health issues.
Essentially, if a baby appears healthy and isn't eating, something is going on - and it needs to be investigated. | 19 | 21 |
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ELI5:Why do astronomers take pictures of things in different wavelengths? | You can think of different wavelengths as different colors. The human eye can only see a small range of wavelengths of light - from around 390 nm to 700 nm - but there's light with wavelengths smaller than 390 nm (ultraviolet) and light with wavelengths larger than 700 nm (infrared).
Just as there are a lot of details in the world that you can only see if you look for specific colors, there are lots of details in the universe that you can only see when you look at different wavelengths.
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Why would I use X language over Y language? | Hello y'all! I am starting a new project, and I was wondering what language I should use. I am relatively new to "complex" programming (classes and threading is where I am now as far as learning). I taught myself c++ 4 ish years ago, but just the basics (up until classes, didn't do anything c++ specific like memory management). Just finished an AP python course for school (but because it was online it wasn't officially AP), and I take Java classes outside of school (at lambas and bytes).
I am unsure which language to use and why I would use it. I am pretty good at learning things, and transferring knowledge (can rewrite things I wrote in python in c++ and vise versa easily) and I learn things fast (bad at memorizing great at improvising and understand concepts). I am willing to learn other languages for this (it's a game), looking especially at Rust and Go (in addition to c++ and python).
So, why would I use Rust or Go over c++ or python (in general)? Looking to pick a language to really learn and focus on (I bounce around too much, learning just the basics from a lot of random languages like javascript, c#, node.js, etc).
I have heard Rust called the "modern c++" because it supports things like memory management (and pointers?) but Rust helps with the more tedious parts, at the cost of "being limited" because it "accepts less" (not sure that that means, explanation would be nice).
What is Go for? I know google made it, as a more readable and reasonable c++, (more python esq look), while still being compiled.
I am open to other languages to learn, but preferably they are like c++ as far as use cases (compiled, 'fast', I will be mostly making games).
I know Python is used for a lot of 'big data's stuff, but what else is it used for? I have used it for scripts (part of my xmobar used python scripts for a while), but I have heard it's bad for games (no built in threading, and not compiled)
I am specifically making a game like Pacman, but without walls, and just 1 coin that moves when you get it. (Terminal output, with a nested for loop to draw the X and the Y). Which language should I use and WHY? (Really looking for the WHY, or type/style of language)
Thanks in advance! | This is really dependent on the application you are making. If you’re trying to make a web application C and C++ would be a bad choice. Use Python or JavaScript (IMO). If you’re application needs to be efficient and you are needing to access hardware elements directly, use C or C++. Choose the best language for the job. You wouldn’t go to a French bakery and try to order in Swahili. | 20 | 28 |
ELI5: How can the body of some animals like Cows, Horses, etc. that only eat grass make those huge muscles? | They only eat vegetables, yet they have huge muscles. Their bodies are full of protein. How is that possible?
**In bodybuilding they say you need to eat high protein foods like beef and chicken to make muscles. It doesn't make any sense!** | First of all you need to consider that all plant matter, or every living being to be exact, contains all essential amino acids that are needed to assemble the proteins needed. The common claim that only some foods contain "complete protein" is utter bullshit - even apples and potatoes theoretically could supply us with sufficient amino acids to get by, we only need eat insane quantities to do so. The efficiency at which the pure protein of food can be used also varies by a large margin.
Animals that can digest grass need to eat a lot of it, but by doing so they can get plenty of amino acids and most other essential nutrients to thrive.
Now the reason bodybuilders usually recommend eating meat is that they aim for very low body fat and optimum muscle growth. One way to achieve that is to eat way more proteins than the body can use to grow (the amino acids can be used as source of energy otherwise) while avoiding fat and sugar, so lean meat and eggs are pretty good foods for that.
If you merely want to get ripped you can be a vegan and grow muscles just fine. Legumes like beans and peas, and grains contain a significant amount of protein, and combined they can be used very efficiently (grain lacks one amino acid legumes have plenty of) | 12 | 32 |
ELI5: How come sometimes my finger smoothly glides over the surface of my phone screen, but sometimes it drags and leaves a streak even if I just washed? | There are several factors that can affect how much resistance you have while moving your finger across your screen. For one, the harder you are pressing your finger down, the more friction there will be between your finger and the screen. You may do this without realizing this. Secondly, different amounts of sweat and grease may be present either on your fingertips or on the phone screen itself. If your hands are warm/sweaty or if it's warm in the air, you may get a more greasy interface between your fingers and the screen. | 18 | 88 |
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Why is there a social stigma about living in your parents house in Western countries? | Im not sure if someone already asked this before but why is this a thing on western countries? (US/Canada) Im Asian M23, grew up in Asia and me and my family moved in Canada when I was 19. I made friends at school and work and I’ve been asked few times where I live and every time I live in *redacted* with my parents there’s always something wrong with their reaction about it. Back in my country it’s perfectly normal to live with your parents until 30 or even older. Some people even get married and live with their wife (if you’re a male) in his parents house. I live with my parents here in Canada but I never asked them for money and anything. I give my share of utility payments, buy and cook my own food, pay my own car payments and credit card debts and student loans and I dont see anything wrong with that. Also, I don’t think I can afford with my current financial situation. I earn around 3kCad$ per month and around 60-70% of those goes to those stuff mentioned above. Usual rent in my city is around 700-1000 even with a roommate. I’m not lazy and I’m not trying to sound rude and ignorant but these people who asked me that are living on their own lives literally cheque by cheque and struggling to make ends meet. I dont see the point on moving out of your parents house when youre not financially stable and has some money saved up. Im not saying that im plannig to live with my parents forever but im going to wait to atleast have a decent paying job and money saved up. Atleast 2-3 years from now. | To follow up, is there much research on prestige hierarchies in general? If there's pressure woven into the psychosocial fabric to demonstrate an ability to pay for things that aren't necessities and to dress them up as if they are necessities to cover up the aforementioned fabric, would we ever find out about it? Are some things too ingrained for an experiment to tease out the contributing factors? | 20 | 143 |
ELI5: Why is it that a building with the AC set to 70 degrees on "cool" mode is colder than a building set to 70 degrees on "warm" mode? Shouldn't they be the same temperature? | Upper and lower boundaries. Cooling to 70 activates cold AC when temp goes ABOVE 70. Warming to 70 only activates heat AC if temp goes BELOW 70. If the building is above 70 then heat AC will never turn on because it's waiting for building temp to drop below 70. | 23 | 18 |
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[General Sci-Fi] Do universal translators improve interpersonal relationships by smoothing out flukes of language/mistakes? | Do universal translators (babelfish, ST and so on) translate the meaning of the spoken words, or the intent behind the words as they are constructed in the speakers mind before they are spoken ?
It’s been made evident in some stories that the grammar and languages of alien civilisations are so different that straight up, live translation of words as they come by would either be impractical, or impossible. I have read about theories according to which the translator devices/systems were actually relying on brain waves/nervous system and other clues to determine the message without having to rely on the words themselves. Assuming this is true, what would that mean for any random interactions where words can get jumbled and the normal spoken message be muddied ?
I’m thinking of any interaction leading a human experiencing a lapse of reason to say “sorry, this came out wrong / I used the wrong word / can’t remember the name for this thing here/I mixed two sentences together”)
Would a translator literally translate the mistakes? Or would they, by being closer to the original intent, short circuit the mechanism by which people get their words messed up? And if this was true, would it not greatly improve relationships overall, diminishing the hurtful phrases, misunderstandings and frustrations of daily life? | Probably depends on how advanced the translator is. For example the TARDIS in Doctor Who is capable of translating almost all languages fluently and into whatever contemporary version of the language the listener understands and there's never been any cultural clashes as a result of this translation. | 15 | 24 |
Why is it that natural remedies occur so often in plants, but rarely if ever in animals? | Consider the chief difference between plants and animals. Animals can move, plants can't. If an animal needs to defend itself, it needs to move faster, or have more muscles, or have teeth and claws and so on. How does a plant defend itself? It can't run away from a predator. It can't bite or claw at an enemy.
So how does a plant protect itself? Aside from maybe some thorns, they use chemicals. There is much more pressure for a plant to synthesize new chemicals that can be used to defend itself, making for a vast array of chemical compounds that may potentially have use in human medicine. There is not the same pressure in the animal kingdom to synthesize unique chemical compounds.
Consider the smell of cut grass. Why does it smell that way? It's the smell of trauma. The grass is basically sending out a distress signal, a category of compounds called "green leaf volatiles". One effect these compounds can have is to lure bugs that eat caterpillars, which like to eat grass. | 15 | 16 |
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ELI5: What is Determinism? | Determinism argues that basically all choices and actions were previously determined by things in your past/genetics and other things like that.
Because of this, Determinists argue Free Will doesn’t exists and any impulsive actions you think you’re doing have been doing were actually decided way beforehand.
This is a huge simplification, hope it helps! | 31 | 49 |
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CMV: There is no way to justify "Honor Killings" of women deemed to have brought shame or dishonor to their family. (Warning, I think its safe to say some of the answers solicited can severely offend). | I've recently stumbled upon an article talking about a person who will defend Honor killings in the upcoming Festival of Dangerous Ideas. While the western mindset has in many instances created outlandish and oftentimes vitriolic opinions of cultures and people foreign to them, the popular "western" notion of honor killing being savage and barbaric cannot be questioned. To subjugate a human being under a perilously unfair and draconian standard with failure to adhere being met with death ( oftentimes without due process) merely because one is born a woman is a crime against humanity.
Here is the article:
http://www.smh.com.au/nsw/honour-killings-speech-prompts-boycott-of-festival-of-dangerous-ideas-20140624-zsk03.html | Why do you want your view changed?
Also the article didn't list the pro-honor killing individual's actual arguments at all. So we don't really know what his perspective is other than what seems to be hysteria from conservative people in a country with a terrible history of racial problems and a recent national hard turn to the political right wing. | 12 | 20 |
[Star Trek] Why have the civilizations of Star Trek expanded SO SLOWLY? | It seems like the biggest limiting factor is the crystals needed to power starships... but is it really so hard to harvest energy from other sources and store it in some other form (since it apparently is utterly impossible to synthesize the necessary crystals, even if one uses the highest quality replicators and parks next to a star or two)?
If nothing else, couldn't they start spamming colonization pods that basically consist of frozen colonists + industrial replicators + solar panels (or some other such energy gathering device) and just not thaw out the colonists until enough progress has been made for them to live reasonably comfortably?
***
And what about the Borg? It seems like all they need to do is make ships and... that's it. They don't even need to colonize planets, do they?
***
And now that I think about it, how has the galaxy not been overrun by sentient machines? Are they really that rare? It seems like any race that has overcome the need for colonizing planets, maintaining atmosphere, etc, would have such a gigantic advantage over everyone else that it would be no contest unless they got snuffed out by a more advanced race before they had a chance to blossom.
They could focus on using all their trilithium/dilithium for space travel and use other energy sources for staying alive. All other resources could be channeled into making ships and reproducing. Hell, the two need not even be mutually exclusive. | * Population growth is massive limiting factor, you only really colonize as fast as your population expands (and even then, the need to actually go and settle new lands is low)
* Terraforming is an expensive, long process and otherwise the number of habitable planets actually isn't that massive when you get right down to it, and when you further split things up by travel time and competition from other powers, you get relatively stagnant borders.
* Not everything can be replicated. There are plenty of resources that still require extraction and refinement, and the quality of replicated goods is generally seen as middling. Perfectly acceptable for consumer use, in a sense, but for starships, heavy industrial equipment, really anything that is quality dependent you'll want to use standard processes to produce. | 26 | 22 |
How would a blind person experience LSD? | It would depend on the cause of the blindness. LSD is an agonist of 5HT2a receptors and works at the level of the visual cortex. So if someone had a non cortical blindness due to for example a cataract it should still be possible for them to experience the visual effects of LSD. If the cause of the blindess was cortical (e.g. stroke) they would likely not experience visual effects.
It should be noted that LSD acts on many other brain areas apart from the visual cortex and it has many other effects on cognition and perception apart from the more well publicised visual effects. | 124 | 162 |
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CMV: I believe universities should be more exclusive | I think everyone is going to agree that the current educational status of the united states is bad at best. The extremely high costs and the saturated laboral market are driving young people to start their lifes with a massive debt on their account and uncertainity on whether or not they are going to be able to get the job to pay for it. My point being that I eleibe this problem woulb be solver, or at it would help drastically if universities were much more exclusive. Full disclousure: Im not american, I follow the british educational system, which mostly suffers from the same problems than the american, gowever I opted to argue from an american view so that most people that are going to read this could relate to my arguments. In the british system there is an average made of all the exams and a grade "C" is calculated from this average, this means that if a student gets a 58% in an exam and the average of the students is 64% he will get a "D", if the average is 55% he will get a "B". This ensures that only a fraction of the class gets "B" and "A", the reason why Im explaining this is because Im unsure of whether or not the american system has a similar approach. Anyways, my underatanding is that if universities only admitted for entry students that had an average of "B" (or a gpa of 3, correct me if Im wrong on this) this would unsaturate the job market for university students, drive the prices of higher education down and also open the eyes to a lot of laboral opportunities that are looked down upon just because of voncept that you need a university diploma to be succesfull in life. (By the way Im not a native speaker so if I had spelling mistakes please overlook them and focus on the view) | Education is important for its own sake. Universities aren't just job factories, they teach other important skills. Things like critical thinking, research skills, a base knowledge in core subjects like science and history, a widened worldview giving you empathy for the "other." Even if you take those skills and use them for nothing but flipping burgers or digging ditches, all of society is better for having more people be competent in these skills.
Consider the insane amount of fake news floating around social media that gets bought hook, line and sinker, the people who deny basic scientific truths like climate change and evolution, the way the American presidential race has become more about a popularity contest and sounding good than people thinking about the actual issues, partially because they don't know how to. Some of these problems could be at least not as bad if everyone had the right to a college education. Even better, if they started teaching these skills before college. | 12 | 16 |
Can a [B.S. in computing and data sciences] help me land a job as a software engineer? | The university in my city doesn't offer a B.S. in computer science or in software engineering (both available in other cities), it only offers a [B.S. in computing and data sciences]:
Curriculum: https://docs.google.com/document/d/1-PV_bSXL9Il7F7JdZqyYYQqNqczz76gyEUetNoy1rZI
Would the later be good enough for an aspiring software engineer, or should I travel abroad and enroll in a university that offers a computer science or a software engineering degree?
Any advice is much appreciated :) | From the curriculum, it leans heavy towards statistical / math foundation, so indeed it points towards data science. Nothing wrong with these, if you dig these. It probably covers 30-50% of CS.
I find less of these CS related staple subjects like: operating systems / systems programming / assembly, programming languages / paradigms / design, hardware / networking, software engineering / architecture. | 12 | 23 |
Why does an accelerating electron(or any other charged particle) radiate electromagnetic radiation? | Imagine you are very far away from a charged particle, and you can detect its electric field.
Then the particle starts accelerating. The electric field far away from the charged object is no longer the same. However, the information that the source of the field has changed can only propagate at light speed. So the electric field has this disturbance propagating outward at the speed of light, which is what we call electromagnetic radiation. | 26 | 22 |
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ELI5: How are we able to measure space? | For example, I read about the Pillars of Creation and how they’re 4 light years tall and that equates to something like 23 trillion miles long. How do we know that it’s 4 light years long?
Or another example, the galaxy that we’re in is 100,000 light years wide or something like that. How do we possibly know that?
And i guess i also have a related question but how can telescopes see so much to begin with ?
My mind can’t wrap around the understanding of how we’re able to observe space lol, it’s so daunting how small we are. | There are several methods to calculate the distance of a celestial body. Which one is used depends on the exact circumstance. Here are some of the most important methods:
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* **Parallax**: Earth orbits the sun. In the process of this orbit, we change our position in space relative to a celestial body (just like you see a nearby tree in a different position if you move 10 steps to one side) Using trigonometry, we can calculate the distance to the celestial body in question.
* Advantages: very precise for close objects, no complicated instruments needed.
* Disadvantage: only possible for close objects
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* **Spectral emission**: Stars emit photons with specific wavelengths based on the material they are fusing in their core. We can identify the composition of a star by analyzing those photons. Due to the expansion of space, however, the wavelengths of photons emitted very far away get redshifted. That means, their wavelengths get longer the further they travel. By comparing the wavelengths of the photons we *measure* to the wavelengths the photons *should have* we can calculate the distance those photons traveled. And thus the distance to the celestial body.
* Advantage: Possible over longer distances
* Disadvantage: The object has to be bright enough so we can measure spectral lines reliably
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* **Standard candles**: Standard candles are celestial bodies of known luminosity (~brightness). We know this luminosity due to the characteristics of some bodies (special types of super novae etc.) By comparing the absolute brightness to the apparent brightness (the brightness the object has vs the brightness we see from the distance) we can calculate the distance to the standard candle. By identifying standard candles in distant galaxies and nebulae, we can infer the distance of those structures.
* Advantage: Possible over long distances
* Disadvantage: We need to find standard candles
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To grad students/established professors: how do you get rid of researchphobia or just general anxiety of doing research? | So I am planning to enter grad school. I know I just have to because my dream job requires me to have at least a masters degree( I want to teach college). I only have like one or two research works (one special problem and one undergraduate thesis) and both are deemed unpublishable in journals. Now this may have put a dent on my confidence doing research but I can summarize my reasons on why I generally loathe/fear doing research:
1. What if my research is not journal worthy?
2. I feel like I lack the training to even pull off a good research topic. I haven't done a lot of laboratory techniques on my field (cell biology). Most of my trainings are pure lecture classes with a little bit of paper reportings.(Case in point: molecular genetics. I know the gal and ara operon machinery and viral genetics but I have never done a recombinant DNA technology experiment.) And most research technician jobs require experience so I cannot apply to those either prior to applying to grad school.
3. I feel like everything has been discovered already.
4. They said that in academe you should be writing for grants. I don't even have the creativity to think of a good topic. My thesis was just a sub topic under a project of one of my professors, so I know the idea didn't come from me.
5. I feel like my writing skills are not up to par with like science standards. I still make grammar mistakes from time to time.
6. I sometimes lack the comprehension skills to understand a single paper. Takes me like 2-3 days just to fully absorb everything in it. I blame my lack of hands on training lol
7. Overall I think I just have some rejection sensitivity dysphoria lol
How did you overcome this (if ever you went on this stage)? Any suggestions? I think I gotta clear my mind of this if I am to enter and apply to programs next year.
Your advice is greatly appreciated. | Read lots and lots of papers. Read so many papers that you properly understand them and can see the flaws in them. IME this is around the 100-200th paper mark, if you’re reading casually (which you usually will be).
Nothing shatters those rose-tinted glasses quite like reading the kind of flawed work that gets published in reputable journals. No one has discovered anything, and what they have discovered, they have incorrectly characterised. And the same will be true of your work too. Everyone’s work is a work in progress, and then we die and hand the baton on to the next generation. | 27 | 37 |
How would universal healthcare affect the job market? | I've always been told when job hunting to look for benefits package, not just the salary. I know health insurance (and vision/dental) are not the only aspects of a benefits package, but they're a major one. Would the view just skew more towards salary? And would salaries overall increase since they're not paying for employees' healthcare anymore? | There's some evidence that employer provided health insurance decreases labor mobility because workers are afraid to lose their insurance even if their total compensation would increase if they switched jobs. | 15 | 34 |
ELI5: Why does radio reception sometimes increase when we stand next to a radio or touch the antenna? | Your body reacts to electromagnetic radiation (which includes radio). FM just happens to have frequencies near the resonant frequency of the human body. So your body acts like a tuned antenna for some stations. | 13 | 18 |
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If light is a constantly shifting electric/magnetic field, why does it not interact with other external electromagnetic fields? | I understand that photons themselves lack charge, and light interacts with things like other photons and electrons etc. but why don't the electric and magnetic field interact with, say the magnetic field around a magnet? | Maxwell's equations are linear, which means that EM fields obey the superposition principle. If you bring together two sources of electromagnetic fields, the net field at any point in space is simply the sum of the two individual fields. | 13 | 17 |
ELI5: How does 'glow-in-the-dark' work exactly? | I'm sitting here sleeping at a family member's house in the Seattle area and there's a big blackout in my town. The room I'm in has those stars that stick to your ceiling and glow when you shut the lights off. How does this work exactly? Additionally, I've noticed from past experience that using a blacklight as the light source really intensifies their glow. How come? | Incoming photons, which are a form of energy, are absorbed by molecules of (usually) zinc sulphide. This energy pushes an electron in one of the atoms into a higher energy orbit (state would be a better word, since electrons don't actually orbit). It's not happy there, and will eventually fall back, at some random time in the future, and the energy released as it falls back comes out as another photon - which is light.
To start with, there are lots of energised electrons in the material, so there are lots of chances for some to fall back, so the glow is bright. As they fall back, there are fewer and fewer ready to jump, so the glow gets dimmer and dimmer.
UV has a much higher energy per photon (which is why it burns your skin when you get sunburn) so it's able to bang a lot more electrons up into higher states, so there's more energy stored, so the glow is brighter as it's released. | 31 | 68 |
What is the diference between rationalism in Descartes and rationalism in Kant? how do they utilize rationalism differently? | An important distinction would be that, for Kant, concepts without intuitions are blind, meaning that we cannot posit entities on the basis of reason that do not correspond to possible experience. This includes proofs for the existence of God, free will, and the immortality of the soul.
For Kant, we can only use reason to make determinations within the limits of experience, while the rest remains thinkable, but not knowable. | 17 | 30 |
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Could the conditions for life be different than ours in another part of the universe? | Basically, can other life forms in the universe exist without our specific standards of living. Is it possible for life forms to exist not dependant on water or oxygen? Why is water the standard for looking for life on other planets?
Edit: got more than enough great answers. Thanks everyone! | We don't know what the full range of conditions is under which life can exist.
What we do know is that life is possible in places like the Earth.
So if you were going to look for life, better to spend your efforts in the kinds of places where we know life can exist, but that is not the same as saying life can't exist in other conditions.
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ELI5: The Drake Equation | All of the terms are probabilities that certain things will happen. That a star will have planets; that a planet will develop life; that the life will develop intelligence; and so on. None of these probabilities are zero, because we know that it has happened at least once, but we don't really know how much larger than zero they are, so we have to make educated guesses. When all multiplied together, you get the probability that a given star will have intelligent life, which you then multiply by the number of stars in the universe to determine about how many planets there might be with intelligent lifeforms.
Basically, the point is that it's quite unlikely that mankind is the only intelligent lifeform in the universe. | 10 | 15 |
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ELI5 is power only generated by spinning turbines? (besides solar) | Nuclear power appears to be a powerful way to make steam that spins a turbine. Same with geothermal, wind, & hydro. Maybe not solar? Isn't energy lost in the multiple energy conversions (heat, water state, kinetic)? Is it theoretically possible to have a power source that more directly moves electrons through a circuit? If solar is the only one that can, it's limited in efficiency and where it can be used. What about power generation undersea or on Ganymede or something? | Electricity is generated by the movement of electrons through a circuit. You seem to understand that part. That motion of electrons can be cause by several different methods. Solar uses photons of light to push electrons across a semiconductor and generate a voltage. Fuel cells use hydrogen and a catalytic material to strip an electron off and generate a voltage. Spinning rotors use mechanical motion to cause changing magnetic fields to generate voltage. Thermocouples use heat differentials across different materials to generate voltage.
Thing is, all of these methods include losses. Transferring one type of energy to another always will. It just so happens that spinning rotors have some of the best efficiencies, so they’re used most often. | 688 | 586 |
Why companies can't chemical ananalyze, for example, Pepsi, and produce identical mixture on their own? | I believe some things are patented out - but then are not a secret. For example WD-40 oil is not patented and its recipe is secret, why people just don't analyze it's contents to produce a copy and gain huge cash? | Well there is no machine that you can pop a sample of something into and get out it's chemical composition. Qualitative analysis (the process of finding out what a sample of something is made of) is a long and difficult process that is normally very specific to the material you are looking at. Not only that but this process would only tell you what exists in the sample, not any manufacturing techniques used to create the sample.
And brands like WD-40 use their reputations just as much, if not more, than their actual product to make money. Even if someone was able to recreate WD-40 it would not sell **nearly** as much as the same product just with a WD-40 label.
AND most of the time competing companies do not want the secret formula to their competitors products. For example Pepsi was offered the formula to Coke-a-Cola multiple times and turned it down every single time instead turning over the people who offered to sell the information to the FBI and Coke-a-Cola.
Edit: Unrelated but Pepsi is actually the tastier product according to a double blind taste test done in the 70s. Coke-a-Cola still out sells Pepsi mostly due to branding and reputation. | 36 | 56 |
ELI5: If the flu shot contains a non-active version of the flu, then why are "flu like symptoms" common for the days following? | the non-active proteins trigger an immune system response which can involve some inflammatory system responses.
once the immune system is activated for that infection your body will react more readily if the actual infection gets into you. | 31 | 24 |
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CMV: It's not "anti-science" to include transgender people with their gender of identification. | Critics of transgenderism (?) say that biology shows there's only two genders, male and female, based on sex chromosomes (which are implicit from one's anatomy and hormonal balance if one's chromosomes are not known). After all, biology classes do say that men have XY and women have XX. To not lump in transgender people with members of their biological sex, then, is denying biology.
I know that it's undeniably clear that we are a sexually dimorphic species. The division of people with XX chromosomes and people with XY (with their respective anatomy, sex hormones, etc) is about 50/50. This is something that can be empirically tested.
But if you were to say something like "people who have XY chromosomes and this kind of anatomy are men, and people with XX chromosomes are not and cannot be"--is that a statement that can be empirically tested?
My point is, it's only a "scientific" statement in the sense of "used for scientific purposes," not "demonstrable empirical fact of nature." Including transgender people with their identified genders when appropriate does not deny empirical facts of nature, as critics claim.
The statement "people who have XY chromosomes and this kind of anatomy are men, and people with XX chromosomes are not and cannot be" is merely a statement defining the boundaries of a category. These categorical criteria serve a purpose in many scientific, medical, anthropological, etc. contexts, but they need not be ironclad in all contexts. Different contexts sometimes call for categorical words to have different criteria!
Here are **four** examples of categorical words that have biology-based definitions but don't always adhere to those definitions in all contexts:
* Genetically, I'm <5% Jewish. This may be relevant in some medical contexts, bringing up what kind of conditions I or my progeny may be predisposed to. But in, say, a demographic survey, I wouldn't call myself Jewish. It's just not relevant in my life, neither ethnically nor religiously.
* I'm pretty sure we all understand that to be a "father," such as for the sake of celebrating Father's Day or contact info for the kid's school, need not involve the actual physical sire of the child. For many purposes, it's the male figure who's raised the kid as a typical biological father would. But if you were to go on the Maury show to be told, "You are not the father!", you'd *know* he doesn't mean "You are not the one who's been raising this boy alongside the mother his whole life!"
* Rabbits and hares were declassified as rodents in 1912 because their teeth suggested that categorizing these animals in a different order would reflect phylogenetics better. But in pet stores and pet owner communities, they might as well be rodents because they're lumped in right alongside them.
* To put it pithily, "knowledge is knowing that a tomato is a fruit. Wisdom is knowing that it doesn't belong in a fruit salad." To put it more maturely, yes, tomatoes are considered "fruits" by botanical criteria, but in culinary contexts, they're not.
If people want to discuss whether it's a good shift to categorize transgender people by non-biological criteria in non-biological contexts that distinguish between men and women, that's worthwhile. It's just that the "anti-science" angle reflects a misunderstanding of what a scientific fact is, I believe.
In short, the big trans question isn't so much whether the biological definitions of male and female are valid so much as it is whether these biological definitions should serve as the categorical boundaries between men and women in all non-biological contexts. | >In short, the big trans question isn't so much whether the biological definitions of male and female are valid so much as it is whether these biological definitions should serve as the categorical boundaries between men and women in all non-biological contexts.
If you're talking about a context where this is not a useful distinction, why would ANY discussion of gender, biological or identified or otherwise, be worthwhile? | 16 | 40 |
Does gravity have a range or speed? | So, light is a photon, and it gets emitted by something (like a star) and it travels at ~300,000 km/sec in a vacuum. I can understand this. Gravity on the other hand, as I understand it, isn't something that's emitted like some kind of tractor beam, it's a deformation in the fabric of the universe caused by a massive object. So, what I'm wondering is, is there a limit to the range at which this deformation has an effect. Does a big thing like a black hole not only have stronger gravity in general but also have the effects of it's gravity be felt further out than a small thing like my cat? Or does every massive object in the universe have some gravitational influence on every other object, if very neglegable, even if it's a great distance away? And if so, does that gravity move at some kind of speed, and how would it change if say two black holes merged into a bigger one? Additional mass isn't being created in such an event, but is "new gravity" being generated somehow that would then spread out from the merged object?
I realize that it's entirely possible that my concept of gravity is way off so please correct me if that's the case. This is something that's always interested me but I could never wrap my head around.
Edit: I did not expect this question to blow up like this, this is amazing. I've already learned more from reading some of these comments than I did in my senior year physics class. I'd like to reply with a thank you to everyone's comments but that would take a lot of time, so let me just say "thank you" to all for sharing your knowledge here. I'll probably be reading this thread for days. Also special "thank you" to the individuals who sent silver and gold my way, I've never had that happen on Reddit before. | Yes, gravity has infinite range and changes in gravity propagate at the speed of light. It's a very analagous with electromagnetism, ie electric/magnetic fields and electromagnetic waves.
Every piece of matter in the universe is attracted to every other piece of matter in the universe. And when wild things happen, like neutron stars merging, the hiccup in gravity you feel from them spiraling into each other at half the speed of light arrives in almost lockstep with the light from the explosion from the matter they fling off. | 3,727 | 6,459 |
ELI5: why do we get itchy when we are sweating while sitting/ laying on grass fields? | Wow, I dunno what to say, this blew up. Thanks for all the responses everyone! | Even for those without allergies, grasses and plants contain many organic compounds, like phenolic acids, that can be a skin irritant. Parts of the grass (especially freshly cut, dry grass) can also cause mechanical injury to the skin and elicit an itching response.
Sweating likely dissolves these irritating compounds and allows for closer contact with the skin. | 2,151 | 3,619 |
ELI5: Why is "0! = 1"? | If n factorial is n(n-1)(n-2)...(3)(2)(1),
Why is 0 factorial=1? If 0=n, should the answer be 0 due anything multiplied by 0=0?
EDIT: Wow thanks for all the good responses! Never actually expected this to make it to my top post, but Reddit never fails to amaze me! | A factorial represents the number of ways you can organize *n* objects.
There is only one way to organize 1 object. (1! = 1)
There are two ways to organize 2 objects (e.g., AB or BA; 2! = 2)
There are 6 ways to organize 3 objects (e.g., ABC, ACB, BAC, BCA, CAB, CBA; 3! = 6).
Etc.
How many ways are there to organize 0 objects? 1. Ergo 0! = 1.
This is consistent with the application of the gamma function, which extends the factorial concept to ~~non-positive integers.~~ all reals EDIT: except negative integers! | 997 | 606 |
Eli5: how does assembly code work? | A computer is a machine that only knows how to follow a list of basic instructions.
It can read values from memory, do basic math on them, and store the results. It can also compare two values and jump to a different place in the instruction list based on the result.
The computer uses numbers to represent these instructions. So for example, 1 means load and 2 means add, etc. A computer program is stored as a list of numbers.
Assembly language is just a simple translation of these numeric instructions into readable words like MOVE and ADD. When you write assembly, you are writing directly in the basic instructions the CPU understands, but with codewords instead of numbers.
On the other hand, high level programming languages let you write English like instructions for advanced operations, like printing to the screen or connecting to another computer. The compiler or interpreter does the job of translating these into the sequence of assembly code that the computer can actually follow. | 42 | 24 |
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Is bait scientifically classified as a tool? | If a predator uses bait to catch it's prey, has that predator used what scientists would classify as a tool? | It depends on whose definition you are using.
Some researchers consider a tool to be an object that is manipulated by the animal to extend the physical impact the animal has on itself or the environment. Some researchers will differentiate "tool use" and "object use".
A bird using bread to catch a fish may be consider using a proto-tool.
For more info search "tool use by animals". | 16 | 22 |
ELI5: What exactly is aging? | On a cellular level, what is the exact process? | As DNA replicates, data is eventually loss/damaged, resulting in aging.
Think about making a copy of the document, then further making copies of the copy. Eventually, you find the document is muddy with marks and words on the document will become more and more distorted.
Same thing happens with DNA | 47 | 20 |
[Back to the Future] What exactly is the time machine travelling through that causes it to frost over completely? | The very first time that Doc Brown tests it (and the others too, I think), the time machine arrives completely frozen over, to the point that ice cracks when he opens the doors and it's painful to touch.
The parking lot is wet, meaning it didn't freeze naturally from the air temperature, either.
Additionally, where does the water come from? The DeLorean was driven to the lot inside a closed truck and the rain has obviously stopped, meaning that it couldn't have been wet beforehand. | Theoretical: the time displacement field extending from the aluminum body of the car on outwards saps all energy right down to an atomic level, resulting in the body of the car becoming quite close to absolute zero. One the field is gone it begins absorbing the ambient warmth around it again (there was some delay before Doc reached the car to touch it) but it's still extremely cold for a short while.
The DeLorean isn't actually traveling through anything between the two points of spacetime, as seen when we're along for the ride to a different time. A quick flash of light from the formed time displacement field and then you're in the targeted spacetime once it fades down again.
The moisture is just condensed humidity from the air flash frozen to the body of the car. Like your windshield frosting over in winter. | 35 | 24 |
ELI5: Why do we spend billions and billions of dollars on cancer research, and still use Chemotherapy as the most widely used treatment. | After having people come to my door asking for support in Cancer Research, I asked them how much further we've come in the last ten years, and they couldn't tell me. And they said that Chemotherapy is still the most widely used treatment in America for Cancer. After having multiple family members who have died from Cancer after going through Chemo, I am just curious how effective Chemo is against Cancer cells, and where is all the money going that we donate if it's not making any widely known progress. | Cancer is a broad spectrum of diseases that involve uncontrolled growth or production from your own cells. As broad a term as cancer is, chemo might be even broader. Chemo is medication that kills cells or targets them for killing, but does so preferentially to cancer cells than non-cancer cells.
Cancer research and effective chemo is making a lot of progress, as pretty much everyone on here is saying. Money for cancer research goes toward staffing cancer research centers/hospitals, testing chemo drugs, and testing cancer screening strategies, just to name a few things. There are MANY cancers that we have developed a very effective chemo regimen for. Testicular cancer is one that we are able to very effectively treat with chemo. More recently, a specialized chemo drug for Her2 positive breast cancer has been developed. This form of breast cancer used to be a death sentence, now it's one of the more favorable breast cancer diagnoses because of the efficacy of our available chemo.
You'll never turn on the news to a headline of "chemotherapy stops all cancer all at once." What's unfortunate is that the many small victories in cancer research don't receive the attention that they should, leaving the lay person to believe that there hasn't been progress. | 17 | 30 |
My Boss Sent Me A Journal Article to Read and I Can't Understand It... | Hello everyone,
This is my first time posting in this sub so please bear with me.
So, I graduated with my BA in Psychology this past May. A couple of weeks ago I started a job as a Research Assistant working with a highly distinguished professor in the field of cognitive science and abnormal psychology. Now, cognitive science (or any science for that matter) was never my strong suit. I also fulfilled my science requirements in undergrad 2 years ago, so I forgot a lot of information. I was hired mainly to work on one of his projects that has nothing to do with his primary research interests, but aligns perfectly with my interest of abnormal psychology and working with a completely different population.
Last week, I got hired to work on another project. So now I'm working part-time in both projects. My boss sent me a lengthy article to read, and I can't understand a majority of it. My boss mentioned that if I had any questions, I can just ask. But, I'm afraid that I'll look incompetent and that I really don't belong in the lab. The paper was way too advanced. I've been researching key terms, going on websites and reviewing notes from years ago. Although it does help, I feel so inept and that I don't really belong in this lab.
Imposter syndrome has already got the best of me. I'm one of the youngest working in the lab. Most of my co-workers have PhD's. It's so intimidating. I know the common sense answer here is to just ask my professor questions, but I've had demeaning professors before and I'm trying to prevent a poor situation.
What do you suggest I do? I'm not considering dropping out of this project, considering my boss really needs an RA for this project. I definitely still want to work in this project because I love learning new things. I'm just overwhelmed with imposter syndrome symptoms and I'm not sure where to begin.
Any advice would be greatly appreciated! | Look at the older papers cited in the article; it's likely these will provide some of the background for how the research in the article itself came to be. Keep going down the rabbit hole as needed.
Are the new project and subsequent article cognitive science-based, and that's why you feel you don't understand them? Try to fit the paper in with the concepts you do understand from the new project. Do you need to thoroughly understand everything from the article before you will be able to carry out your duties as an RA? In that case, you will need to explain the situation to your PI. That's improbable, though, ime. | 17 | 22 |
Why don't people have different natural hair colors like blue or green? | Are there any natural hair colors besides red, black, brown, and blonde? | Mammals main source of coloring is melanin, which produces browns, blacks and shade of tan. Other animals such as birds have multiple types of pigment along with melanin including, carotenoids which produce red, orange or yellow feathers. Also Porphyrins, an amino acid that can produce red, brown, pink and green colors. The source of these pigments comes from many of the foods that birds eat. So the way a birds body digests and converts these substances is another thing that our bodies did not evolve to do. The forth material that produces colors like blue and green is keratin. Our hair is made up of this same material although the way keratin is used in other animals is a bit different. The structure of the keratin reflects certain light waves which makes it appear blue. The color of the keratin isn't blue itself. A birds feathers on a microscopic level can have a structure that reflects blue light. Butterfly wings also work in this way. Our hair doesn't have this complex structure to do the same. | 23 | 23 |
ELI5: Why some video games allow in game, real time graphics changes, and why other video games require a restart before applying the graphics changes. | I'm curious as to why this is the case. Please explain. Thanks. | Some changes technically require releasing and re-acquiring a resource from the OS, like resolution changes of the game window. That means the game has to release then re-create all the resources associated with the first one, like the textures and vertex buffers.
Other changes require loading different assets, like high vs low resolution textures or models. These shouldn't technically require restarting the program. Likewise for many of the effects settings, like turning on or off SSAA, SSAO, DOF, etc.. That said, it still takes coding effort to add the ability to actually SWAP between different assets. It's often easier to just assume the high-vs-low setting is fixed from the start of the game, and never code the ability to swap our textures and models. Thus, you have to restart the game to get it to load the other set of assets. | 10 | 31 |
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