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ELI5: What causes me to wake up minutes before my alarm goes off, even when I've barely slept? | For example, I woke up at 5:45 am today, like I would normally do to go to work, except I had the day off. I went to bed at 2:30 am, so it's not like I was fully rested either. What causes this to happen? | There is something in our body called a biological clock. If your body is used to doing some things at a certain time, be it waking up or maybe using the restroom. You will generally do these things at those times even when its pointless to do so otherwise. Since you work your body does this to help you not oversleep when its time for you to work.
I hope this helps you. | 16 | 37 |
CMV: an undergraduate degree should not be required before applying for a professional school ( such as medicine, dentistry, law, physiotherapy) | In Canada and the United States, one must compete a 4-year bachelor undergraduate degree before applying for medical,veterinary, dental, or law school. But I do not think that is necessary, and if anything it's just a money-grab by the universities and a waste of time.
In other countries, you can apply to medical, dental, or law school right out of high school. I'm gonna use Poland as an example.
In Poland, you can apply to a 6-8 year medical school program (this does not count the time spent in residency, which varies based on specialty) and attend right after graduating high school. No undergrad needed. And their doctors as just as well prepared as north American doctors.
Same thing for dental school. In Poland, you can just apply to a 6-year dentistry program right after high school. And their dentists are just as well prepared for the job as North American dentists.
Meanwhile in the USA and Canada; one must compete an undergraduate degree before applying to medical school. Same thing for dentistry, veterinary medicine, law, physiotherapy, occupational therapy, and pharmacy school.
An undergraduate degree should not be a requirement, and Canada and the United States should adapt a model similair to Poland's for future doctors, lawyers, dentists, etc. Because:
1. People would be in less debt. A 6-year dental school vs. 8 years years of school (A 4-year bachelor's degree PLUS a 4 year dental school degree). More and more young people are drowning in school debt.
2. We would have professionals ready for the work force faster. This would especially benefit Canada, where there is a huge shortage of family doctors.
3. It takes away a little bit of stress from hopeful future professionals, as it takes away one hurdle. It's better to start a professional right out of high school than it is to have to waste your time in an unrelated degree program stressing over the next 4 years about whether you will get into the professional school of your choice or not. | One good aspect about requiring a bachelor's before advancing to a more specialized school is that it gives the students a checkpoint. When you get your bachelor's, you have to option to continue going right into grad school, or you can take some time off and work. You could pay off your grad school with the work you do with your bachelor's. If you take a six to eight year program to become a post-grad, then it will take no less than that time to profit from any education you received.
Also, it gives students a chance to re-examine their goal and decide if they want to go further. Let's say person wants to be a doctor, but after barely getting through their first four years, they might realize that they don't have what it takes. In that case, at least they still have a degree, and can pursue other avenues related to medicine. If they go to medical school, but fail out after the first year, at least they still have something to fall back on. After the first four years, you realize that you would prefer to work the business end of medicine. Instead of going to med school, you could change course and take business courses instead. If you go for a six to eight year doctor school, you have nothing to fall back on. If you don't finish the full thing, you end up with nothing. If you run out of money on your sixth year, or if you have to quit school for whatever reason, you are no better than a high school graduate. If you realize half way through that you don't want to be a doctor, you either have to give up and lose the last four years of you life, or continue and get a degree you don't want. | 38 | 64 |
How does animal testing really work? | I was thinking about it and realized that I’ve got a lot of preconceptions from my teen vegan years (Yeah, I used to be that guy). I still think we’re unnecessarily cruel to animals in many ways but definitely no longer trust PETA as a reliable source. So, does the US government really require new shampoo products to be poured over cute bunnies’ eyes before entering the market or is that just BS? Can anyone enlighten me on when and why animal testing is necessary leaving the moral discussion aside?
Thanks in advance.
Edit: Thanks for the responses, guys! I’m all for medical testing, which I understand covers the vast majority of animal experiments. I’m still against cosmetic testing, regardless of how the suffering is minimized, but it was nice to hear from people who work at the labs and learning that they do care about their animals.
Also, for the record, I wouldn’t trust PETA to take care of a plant. | I don’t know the specifics for shampoo. But for animal research, before any experiment you need to write up a proposal that dictates why the animals needs to be tested, and the measures you will take to do it in the safest way possible, using the least number of animals. You also need to show why it is imperative animals need to be used, and the good that will come out of it.
It is Incredibly regulated, and scientists take great care to do it the best way possible. At the end of the day animal testing saves lives by providing necessary medication and vaccines that would not be available without it.
| 67 | 38 |
[Star Trek] How does the crew of Enterprise know who to beam up, with only the phrase "(number) to beam up"? | Transportees tend to cluster together, apart from non-transportees, when calling for extraction.
If you hear "five" and see that the guy who called it is standing next to four other guys you can probably just intuit who wants back up. | 28 | 22 |
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ELI5: With "unsolvable" math problems, how do people come up with the problem and why do they think the problem is worth solving? | I am assuming you are referring to math problems which have not been solved, but may be solved in the future like the and Riemann Hypothesis. These problems are usually conjectures (sort of like a hypothesis in science) meaning that they appear to be true for every number, but we have not been able to prove it. Testing every number is impossible since there are infinitely many numbers so mathematicians use mathematical rules to try to come up with a proof and show that the conjecture is true for for all numbers. An example of this is the famous Fermant's Last Theorem that no three positive integers a, b, and c satisfy the equation a^n + b^n = c^n for any integer value of n greater than two. While it appeared to be true for all numbers it took mathematicians 400 years to prove that it is using some very complex mathematics.. These problems often do not have obvious real world applications, however the our understanding of the physical world tends to play catch up with mathematics meaning that they may very well be discovered to have physical meanings in the future. That being said there are math problems like the Continuum Hypothesis which appear to be truly unsolvable and they arise from the axioms of mathematics. | 145 | 457 |
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eli5: why is cancer increasing in young people? | Is it just because we dont die of other things first? | The largest reason why it's increasing for young people is that our techniques and technology for the detection of cancer have improved significantly thanks to all the money thats been going in to cancer research for the past few decades. So we're catching it earlier and more accurately. Even the non harmful benign cancers are being caught sooner.
The other reason is an increased awareness of cancer. People have been educated on what skin cancer looks like and that any unusual lumps really should be looked at by a doctor and not dismissed as something you can ignore. | 74 | 35 |
ELI5: Why do some fruits have small seeds for their size (eg. Watermelons and pineapple) and some have big seeds for their size (eg. mangoes and cherries) | Different fruited plants have different strategies for reproduction, and the seeds can be different in part for that. Some seeds are designed to be eaten, pass through an animal's digestive tract, and get deposited in a nice, nutrient rich, pile of poop. Some seeds are designed to fall to the ground and get some nutrition from the rotting fruit.
And even two fruit with the same strategy can look different because they evolved separately. Different environments will lead to different ways of succeeding. Why are some plants taller than others? Because they each evolved to fill some niche in some way. | 60 | 144 |
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ELI5: the difference between a psychologist and a psychiatrist | I have a feeling I know the difference on some levels, but I still get confused. Especially when I want to explain it to someone else, I can't find all the right words.
edit: thanks everyone for your insightful answers! | A psychiatrist is a medical doctor, who went to medical school and chose to specialize in psychiatry (just like how other medical students choose to specialize in being heart doctors or lung doctors). A psychiatrist prescribes medicine and uses medicine to make you feel better.
A psychologist does not use medicine. Instead psychologists use other methods for therapy such as counselling and making life and mentality alterations to make improve mental health.
Some times psychiatrists don't think medicine is the fix for a patient so they refer them to a psychologist.
Hope that helps.
| 20 | 25 |
ELI5: why does it take us weeks (even months) to feel fit, but only a week of not exercising to feel like we're back at square one? | Our body is a multi-million year old machine that has evolved into being able to adapt to changing environments as we move around the planet and hasn't quite picked up on the massive changes to modern living the past century. You're emigrating, cool, don't need those upper body muscles just need strong legs and feet for moving. You're farming? Cool, need some strong arms to use tools.
Your body gets stronger by muscles tearing and rebuilding stronger. You go and squat 100lbs 10 times four separate times in 10 minutes, your muscles tear. You do that a few times and your subconscious says to itself "Hey, we apparently squat 100lbs 10 times four separate times now. That's what the conscious is doing now so lets rebuild the muscles to be able to do that."
You keep doing that and your body maintains it at that level. You add more weight your body responds by going to a higher level. You STOP doing that your subconscious quickly says "Hey, we apparently aren't squatting 100lbs anymore so redirect those resources to storage because we don't know the next time we'll get food."
TL;DR Muscle takes quite a bit more calories to maintain than fat does so if you aren't using it your body believes it is doing itself a favor by getting rid of it. | 44 | 62 |
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ELI5: Why people deny climate change? What are their arguments? | With the GBR news on the front page currently, I learnt that Greg Hunt (Australian environment minister) is a climate-change denier. I'm currently 17 and have always accepted climate change and have never really thought about why people deny it. | It's a very complex bit of science, that requires a background in climate science to truly grasp the studies that prove man made climate change.
Basically, the Earth has been warming and cooling for its whole history, so it's not just enough to show that the world is warming up, as that could be completely natural. You have to show that it's heating up faster than it should be, which involves looking at hundreds of thousands of years worth of climate data, gathered from multiple partial sources, like tree rings, ice cores, and geologic samples. You also need to account for other man made events, such as the heat island effects of cites, and adjust the data accordingly.
So you've got a very complex science, with plenty of places to manipulate the data, either accidentally or intentionally. Combine that with the idea that it's presumably easier to get funding for more research if your data proves climate change, and you can see why someone might be a little sceptical.
Combine all of the above with a general distrust of the left, and you can see why someone might just discredit the entire argument for climate change on the idea that it's just a conspiracy cooked up by the left to shut down oil companies and the like. | 88 | 54 |
Why is honey the only food item that does not spoil? | Spoilage of food is mainly due to infestation of microbes.
Microbes in food, like almost every other living being, need water.
Honey has almost zero water content. If there are microbes in honey, they would soon lose whatever water they have in their cells to the the surrounding honey, due to osmosis and perish.
You can apply this same rule to oil as well. Edible Oil is a very good natural preservative for perishable foods (e.g. pickles from Indian sub-continent), due to the absence of water. | 86 | 95 |
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ELI5: What's the point of having multiple hexagonal cells in the eyes of insects? | Compound eyes are good for detecting and tracking fast motion, and allow for a very wide field of view, as you can just keep adding more cells as you wrap the eye around the head. Simple eyes, like vertebrates have, only allow a relatively narrow field of view but allow much higher resolution, allowing the use of much smaller eyes and the ability to see things further away. | 81 | 138 |
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For those of you in highly interdisciplinary fields, how do you appreciate the fundamentals of the fields you weren't actually trained in? | As an example, my background is in psychology and behavioural neuroscience, and now I'm working in a field that combines clinical pharmacology and pharmacoepidemiology. But I also do cognitive work (tying in my psych/neuro background) and even some clinical chemistry. (For context, I'm a second-year PhD student.) | Interdisciplinary work requires a team approach. You have team members with the areas of expertise that you need. Aa a second year PhD student, you should be working in teams mostly, while your primary/thesis project should be in your own area. | 10 | 22 |
[Doctor Who] What makes the Time Lords so strong? | Is it just their advanced technology & mastery of time? What gave them the power over time, like being able to know what moments are "fixed" points?
Further, why is the doctor so special? Why don't the Daleks ever just shoot him? | Their bodies are technological marvels, each engineered cell as valuable as the starships of younger species. They have dwelled in the time vortex for ages, developing instincts necessary for survival as time travelers. The Doctor is a social and technical genius whose reputation for thwarting death and predating Daleks goes back centuries. | 34 | 26 |
If carbon dioxide is only 0.0391 percent of the atmosphere, how does it have such a big impact on climate change? | Hi everyone,
I have a teacher who believes that humans are not to blame for climate change and that climate change is not a real thing due to the fact that carbon dioxide only makes up a very small part of the atmosphere. I have tried to research this, but found conflicting results. Can you please help me to find an answer? | People often mistakenly conflate abundance with importance (not just with climate science, but with a lot of things). Consider this: iron makes up only about 0.006% of the mass of an average human. Yet, it is completely essential for us to live (without it the hemoglobin in our red blood cells can't transport oxygen). So any argument that something is unimportant simply because it's not abundant is not valid. | 58 | 22 |
[Young Justice] How do the inhibitor collars work? | They seem to work on anyone and don't have to be prepared specially on a case by case basis, but doesn't that mean every hero's weakness has been identified? If they work externally (ie they aren't injecting something into the wearer, couldn't that tech be scaled up to create suppression fields that could blanket entire areas to suppress villains or heroes within them? If they do work internally, couldn't that be made permanent somehow? Or at least implanted deep inside the target so it isn't just a case of someone ripping the collar off to escape? | They have to be prepared on a case by case basis, but there's wiggle room. For example, when Miss Martian was masquerading as Tuppence, her telepathy and shapeshifting werent blocked, but Superboy's super strength was blocked despite having a different origin than Tommy. | 11 | 17 |
How does mimicry in plants work, how can a plant "tell" what an insect looks and feels like? | Are those plants somehow able to recognize colors? Do they have some kind of sense analogous to sight? | The plants can't tell. The insects, however, can tell what the plants look like. So if a plant looks like a female bee, or whatever this is just a hypothetical example, then a male bee is more likely to try to mate with it and pick up pollen.
Because those tricky plants who look the most like the bee are more likely to have pollen taken/given from them, they are more likely to reproduce. In the next generation, then, there will be some plants who look more and some who look less appealing to the bee. The ones who are more appealing are obviously more likely to reproduce than the ones who look less appealing. Therefore plants that look more like the bee are selected for and, very gradually over many generations, the mimicry will get more and more accurate. | 18 | 22 |
ELI5: What is the Bose Einstein Condensate | Reading the wikipedia article didn't really help me get the full picture. What is it, how do you get to temperatures that low? | Bose–Einstein condensate is a state of matter, like solid or liquid, that happens when certain types of particles called bosons are made to have low energy. Basically this means "made really cold", close to absolute zero (0K or -273°C), which is the coldest temperature possible.
A Bose–Einstein condensate has 0 viscosity, which means it is as slippery as you can possibly be. Because the particles have such low energy, instead of them bumping around randomly like in a liquid, the particles all move in an identical way. This is called a "giant matter wave".
To get to this very cold state, scientists usually trap particles in strong magnetic fields to keep them from moving too much, then use lasers to push them around and slow them down even more. | 10 | 19 |
[MCU] About the dead people after the snap | >!In Avengers Endgame, did the dead know when they were brought back by Iron Man? And secondly, how did the other avengers know that a fight between Cpt. & Thanos taking place? Sorry if these are stupid questions.!< | First of all, not a stupid question.
Doctor strange seem to have been the driving force, he was the only one who knew what was going on. So he called his sorcerer cliq and told them to gather every warrior who wants revenge against Thanos and i believe thats it. | 23 | 17 |
Does it take more energy to heat something up or cool something down, or does it take the same amount? | Just to make a top level comment with the answer. Cooling takes less energy than heating from a physics stand point. The specific heat of a material, energy per unit mass to raise it one degree, increases with temperature for most materials. So fundamentally it takes more energy to heat 10 degrees than cool 10 degrees.
Practically heating is easier because heat pumps are not 100% efficient machines. They produce waste heat when running, when heating this can be used where when cooling you have to make sure to reject it away from what you are cooling.
Edit: /u/AugustusFink-nottle is also right. Heating is more efficient because the work put in contributes to the heating where when cooling you only have the heat moved. | 12 | 33 |
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ELI5: Chinese Politics; how does it work? | I'm a Westerner who hears so many conflicting things about Chinese politics. I like to think I understand the US political system pretty well but the Chinese one I don't understand at all. Is it communist? Is it capitalist? Is it democratic?
Maybe this is the wrong kind of question for ELI5. I don't think most five year olds even know what politics really is. But if someone could try and explain it to me that would be great. | The Chinese government is probably best described as market-Leninism. The economy is fairly free market and capitalist with private citizens allowed to own property and even start their own businesses. The government however is still very similar to the original political system devised by early revolutionaries like Lenin. The government is completely controlled by the communist party from the village to the national level. The party has 3 main responsibilities: personnel, propaganda, and the PLA.
Unlike the US where the US military is the military of the US, the PLA is not the military of China, but is rather the military of the party. As a result the military becomes very powerful politically within the party, something that would never happen in the US. Chinese leaders must have the full backing of the military in order to be effective.
The party is also responsible for controlling the media. The Propaganda Department controls how much coverage should be given to certain topics. For example lots of press coverage was given to the Senkaku/Diaoyu Islands standoff with Japan while protests in Tibet are pretty much ignored.
The party is also responsible for overseeing the appointment of all officials and positions of influence. All personnel decisions must be made with the approval of the Organization Department.
In terms of policy making, the most powerful organ is the Politburo Standing Committee, which is made up of 5-9 party members each responsible for one thing, who then make decisions based on consensus. The National People's Congress (Chinese Congress) is theoretically the most powerful but mainly serves to simply approve everything the PSC does. Occasionally they will make mediate any sort of policy differences/conflicts between different parts of the party.
The most powerful person within the PSC is the Paramount Leader (Xi JinPing) who also holds the office of President, General Secretary of the Party, and Head of the Central Military Commission. He's the most powerful person in China and the person who hold the most power and influence but his word is not the law (as it was back in the Mao era). He must cooperate with the rest of the PSC and party.
Finally there is the State Council, which is headed by the Premier (Li YuanChao) which administrates everything by issuing directives/orders, drafting bills for the PSC/NPC, and balancing the budget. The State Council is where the party and the government fuse together.
tl;dr there are 3 branches: The party, the government, and the military. The party's decisions are made by the PSC (headed by the President/Paramount Leader) with the approval of the NPC. The government is embodied by the State Council, led by the Premier, and is responsible for administrating everything and putting everything together. The military is the PLA, which is responsible for keeping order and its support is also needed by the rest of the party.
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ELI5: Why are there so few engineers and scientists in politics? | According to this [link](http://en.wikipedia.org/wiki/List_of_current_United_States_Senators), the vast majority of senators in the US seem to have either business or law positions. What is the explanation for the lack of people with science and math backgrounds in politics? | Because the skillsets required of the two jobs are different. Whenever this question comes up, it naively assumes politics works how we think it should work in a normative fashion. That everyone should sit down, present their facts, and the most rational decision is made based on the evidence. That's not politics. Mainly because we like to mask that in "because they're all inherently corrupt bastards!" which may have some truth to it, but because the decisions they're making do not have definitive answers. Politics like law involves persuasion and charisma because the answers aren't always distinct and some kind of "compromise" has to be made between all of the proposed solutions and ideologies.
Immense amounts of scientific study and economic analysis goes into legislation. The difference is these think tanks and legislative studies are often motivated by their own political ideals and because the answers are not "easy", many of the projective analysis can be skewed to satisfy the agenda. But honestly the question you're asking is relatively uninformed because it assumes science isn't involved. Scientists, economists and financial experts are all *very* involved. The question is are the *best and unbiased*^^[1] scientists, economists and engineers involved. But to pretend that the fields are completely absent from the process is not only naive but also rejecting the fact that people that possess skills like charisma and the ability to compromise and negotiate are very necessary to the entire process. It's a damn shame we don't seem to have a lot of willing compromisers and negotiators anymore though.
[1] This response is picking up some traction so it's necessary to clarify this. When people complain "the insurance companies wrote ACA!", it's not like the CEO's of UnitedHealth and Wellpoint and the politicians literally sat down to write the bill themselves while shunning scientists, financial advisers and economists. Very qualified financial experts, scientists and economists help write the bills with legal experts. The question people have is related to their motives and representation and whether these people are truly considering the proper factors in their research and writing of the bills not just related to their representative interests. The sciences are all *very* involved in the collaboration process, but it's a matter of is the field attracting the kind of experts that society agrees are most qualified and willing to take into account all interests and affected parties when crafting a bill.
Finally, in the spirit of politics, there is no definitively "correct" answer here, but it's much more complex than "they're too good for the job!" and it's also just incorrect to claim science is completely uninvolved in the political process. | 382 | 586 |
ELI5: Capital gains tax | What are the arguments for why it should or shouldn't be implemented, and what exactly is it? I checked the Wikipedia page, but my understanding is still pretty fuzzy. | If as a private individual you buy something, then later sell it at a profit, you have made a *gain* on that item. Your capital has increased. Many countries have laws that say if you make money in this way then there is tax payable on that profit. | 24 | 122 |
What's the difference between rechargeable and non-rechargeable batteries? | Why are the rechargeable batteries more expensive than normal batteries?
Edit: thank you everybody for the answers! | There are many differences between rechargeable batteries (a group of secondary cells) and non-rechargeable batteries (a group of primary cells) the main differences being the materials used as cathode, anode and electrolyte in the battery as well as the shape, construction and purpose of the battery (pacemakers, emergency lighting, portable power tools all have different energy requirements and associated costs).
A primary cell is a battery that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (rechargeable battery).
In general, the electrochemical reaction occurring in a primary cell is not reversible, rendering the cell unrechargeable. As a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless.
In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants.
The processes and materials required to produce secondary cells are more expensive than those of primary cells so rechargeable batteries have a higher initial cost but tend to be more economical in the long run as you can usually recharge the battery up to 1000 times.
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[the matrix] is technology allowed to advance within the matrix or is humanity just stuck in the 21st century? | And if technology is stagnant within the matrix are all the scientists agents. Or if they are other people trapped in the simulation are they only allowed to make minor advancements? | Experimentation is required for technology to advance.
Since The Matrix is a simulation, the machines can control the outcome of (almost) any experiment, and therefore guide technological development as much as they please. | 54 | 46 |
What do philosophers means they call something metaphysical? | I was told that metaphysical is any and all object that is not strictly physical. Words, numbers, algorithms. But the way some philosophers use it makes me think that the definition i was given was wrong. For example, 'La phenomenologie' by Jean-François Lyotard says that the vision of essence is not metaphysical. I am confused please help me. | While philosophers use the word "metaphysics" without any hassle, it is hard to pinpoint what exactly this word means to a person who has not observed its meaning in use.
Well, think of our actual physical world. When describing the existing world, we utter sentences such as "magnetic field exists", "this object has eroded over time", "this building is red", "a memory has flashed in his mind" and so on. These utterences are strictly physical, but they are interesting to a metaphysian in that they invoke the most general categories within which the world is "carved at its joints". The magnetic field might exist, but what is this "existence" we are talking about? This object might erode over time, but what is this "temporality" we are talking about? The building might have a certain property, such as having red color, but that is this "property of an object" we are talking about? A memory might flash in his mind, but what is this "mind" we are talking about?
So, when philosophers call something metaphysical, by that they typically mean that they are describing the most general features of our physical world, such as existence, predication, modality, mind, identity and so forth. The scientific language of physics makes no such demands, these categories are taken as self-evident there for methodological reasons. | 75 | 53 |
Why are there so many Annular Lakes in Quebec? | While doing just a quick fly over on Google Earth of the Canadian province of Quebec, it is quite easy to spot the preponderance of almost perfectly circular lakes dotted around. If they are named, like lake Manicougan, it says that it is an Annular lake that was formed by an asteroid impact at some point in the Triassic period.
I am assuming asteroids throughout the history of Earth didn't have a bias to strike in areas that would become modern day Quebec, so I would guess the rest of the Earth has been bombarded to a similar degree as the preponderance of these lakes in Quebec. But why has Quebec in particular and maybe a few other places on Earth preserved these scars so well while they have vanished everywhere else? | Two things may provide an explanation. First there are a lot of circular lakes in the area, because there are a lot of lakes in the area. Some of this is confirmation bias. Because there are around a million lakes in Quebec, it's no surprise that many happen to be nearly circular even if not all were created by impacts.
That said, there are several impact craters and it would seem to be a disproportionately large number of them. This is likely due to the underlying geology of the Canadian Shield. It's composed of rather hard igneous and metamorphic rocks which resist erosion, and maintain the shape of craters which would likely erode away much faster in softer substrates. It's also a very old piece of earth's crust with portions being nearly four billion years old. This leaves a long time span for impact craters to be observed where in other locations, mountain building, volcanism, subduction, seafloor spreading, or other factors would erase the record of older craters leaving comparably few intact. | 221 | 433 |
ELI5 what does overdrive or o/d do in cars? | Traditionally an automatic gearbox would select the gear based on the output speed so that the engine was turning at the speed at which it provided the maximum power output. This is good for acceleration and hauling heavy cargo. However when the car was light it was not needed and provided lower fuel mileage. An overdrive unit could be mounted after the gearbox and allow you to select an additional manual gear which brought the engine speed down to the optimal fuel consumption range. This saved a lot of fuel on the highway and wear of the engine.
Overdrive units are not so common now as gearboxes have become a lot smarter and is able to select a higher gear itself when it detects that the power is not required. However you might find overdrive being marketed and even used to label a transmission profile suitable for low power highway use. | 25 | 19 |
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Why do large airplanes retract their landing gear after taking off? | Recently there have been a handful of instances in which a plane had to be landed with landing gear that was stuck retracted. I am curious as to whether the benefits outweigh the risks. | The landing gear cause a tremendous amount of aerodynamic drag at the high air speeds attained in commercial aviation. As a result, with gear down an aircraft can't fly as fast and burns significantly more fuel (for a large passenger jet, roughly twice as much fuel for the same distance traveled). Given that a jet might burn more than 100000 liters of fuel in a given flight, that does not represent a negligible cost. | 65 | 30 |
ELI5: Why do our nipples get hard when it's cold out | This is an interesting question, with an interesting answer.
basically its to reduce surface area so its harder for them to cool down further, as to not get nerve damage, and keeping the body warmer.
/u/penguinluvinman has a great answer.
>When exposed to cold temperature skin reflexively contracts, causing the nipple to become smaller, wrinkled and "hard." The ultimate function of this reflex is to decrease the amount of surface area on the nipple that is exposed to the cold. This decreases the amount of body heat that is lost to the cold and ultimately the amount of energy it takes to sustain homestasis (keeping normal body temperature) in an organism. So decreasing surface area is the ultimate reason why nipples get hard in the cold. It's the same thing as goosebumps on other parts of your skin.
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What does it mean to "be Bayesian" in terms of a way of thinking? | I'm familiar with [Bayes' Theorem](https://en.wikipedia.org/wiki/Bayes%27_theorem) and how it's used in problems, but I've heard people talking about having a Bayesian way of thinking in general, or statisticians subscribing to a Bayesian way of thinking. What exactly does this mean? Is there more to Bayesian reasoning than just solving probabilities? | Frequentists, the usual sort of statistics, define probability as the long-run average of a lot of repetitions of an event.
Bayesians define probability as the degree of belief; a subset of them argue that these beliefs are largely personal, and only asymptotically approach the same value with repeated observations.
There are two sorts of Bayesian applications. First is a whole class of Bayesian statistics, which explicitly incorporate your prior beliefs in something and tell you how to change your beliefs. As an example why this is useful, suppose you want to know if a coin is fair. You strongly believe that the probability of a heads is .5, so if you flip the coin 100 times and get 47 heads, you are likely to believe it is still very close to 0.5, rather than the frequenist estimate of 0.47.
There's a second kind of Bayesian thinking, however, which is probably what you're hearing about here. This is Bayes as a philosophy of science or model of reasoning. Bayes' theorem gives you a good model for how to change your beliefs given new evidence. Being Bayesian in this sense means looking for evidence which would radically change your viewpoint according to Bayes theorem, and valuing multiple lines of evidence appropriately. | 155 | 401 |
ELI5 The difference between Libertarian Economics and Anarcho-Capitalism. | I'm currently looking at various schools of though on economics. I'm confused on the difference between Libertarian Economics and Anarcho-Capitalism.
Could someone please explain like I'm five. | Libertarians believe that a government should exist that supports property rights (e.g law enforcement (police), courts, etc) whereas, Anarcho-Capitalists believe that there does not have to be a government to protect property rights as everything associated with them (law enforcement, courts, etc) would exist without government funding, people would pay for their own security.
So just as Libertarians believe that government doesn't have to fund some things as they would exist privately (e.g, healthcare, education, etc) Anarcho-Capitalists go one step further and believe the same of law enforcement, thus there is no need for a government whatsoever. | 20 | 48 |
ELI5: Why do out of season fruits taste less sweet? Is it that they have less sugar in them? | Fruit usually starts producing sugar as it approaches peak ripeness. Out-of-season fruits are often grown in places where they *are* in season, and shipped to you. So in the American winter lots of apples and stuff come from New Zealand, for example, where it is summer.
In order to ship them from far away and have them not rot on the way, growers will harvest fruit early before peak ripeness. This means they get harvested before they start producing their sugar. | 68 | 71 |
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ELI5: When fasting to promote Autophagy; how does the body know that they should go for the damaged and senescent cells first instead of healthy cells? | Healthy human cells have a protein called MHC 1 on their outer surface. When they are damaged, they tend to lose this protein. Your immune system uses natural killer cells to destroy this type of cell, and activates when your body needs to reclaim materials. Ntcs are active always, but increase activity when called. They search for cells without the MHC 1 protein and kill those first. If there are no more unlabeled cells, the body enacts stricter measures that will target healthy cells as well.
Hope this helps.
Source: just studied this in school | 15 | 46 |
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CMV: Islam is not a religion of peace or tolerance. | The Koran speaks of women as property, Mohammed, Islam's prophet himself was a murderer and pedophile/polygamist who thought women had inherently deficient minds. Today, even moderate Muslim men in many parts of the world violently ensure their wives cover their faces and bodies or "adornments" while outside of the house or bedroom. ISIS/The IS/Taliban, etc. all follow the holy text of the Koran. Jihad has existed as long as Islam. Muslim evangelization has been by the sword as far back as the religion dates. What many explain to be Islamic Extremism is usually just Islamic fundamentalism. Liberal Muslim, LGBTQ Muslim, Muslim Feminist--these are all oxymorons.
EDIT:
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For anyone saying that violence and intolerance are only a misinterpretation of subtext (though many who are educated on the Koran in the thread have explained that Allah's word is strictly set and not to be interpreted), I encourage you to read these passages. If the Koran is a text to be interpreted by it's followers, how do you spin these words to be peaceful or tolerant? I truly don't get it.
>Quran (2:191-193) - "And kill them wherever you find them, and turn them out from where they have turned you out. And Al-Fitnah [disbelief or unrest] is worse than killing..."
>Quran (4:89) "...But if they turn renegades, seize them and slay them wherever ye find them; and (in any case) take no friends or helpers from their ranks."
>Quran (5:33) - "The punishment of those who wage war against Allah and His messenger and strive to make mischief in the land is only this, that they should be murdered or crucified or their hands and their feet should be cut off on opposite sides or they should be imprisoned; this shall be as a disgrace for them in this world, and in the hereafter they shall have a grievous chastisement"
Quran (8:67) - "It is not for a Prophet that he should have prisoners of war until he had made a great slaughter in the land..."
>Quran (17:16) - "And when We wish to destroy a town, We send Our commandment to the people of it who lead easy lives, but they transgress therein; thus the word proves true against it, so We destroy it with utter destruction."
>Tabari 9:69 "Killing Unbelievers is a small matter to us" The words of Muhammad, prophet of Islam.
Ibn Ishaq/Hisham 484: - “Allah said, ‘A prophet must slaughter before collecting captives. A slaughtered enemy is driven from the land. Muhammad, you craved the desires of this world, its goods and the ransom captives would
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EDIT 2:
Any attempt to change my view in this thread has been a apologist answer citing false equivalency, or an appeal to emotion by trying to separate the wheat from the chaff (nice Muslims = peaceful Islam). | All you need to be a Muslim is to follow the 5 pillars of Islam, which are:
-Believe that there is one God, and that Muhammad is a prophet of this God, and publically declare this regularly
-Pray to that God 5 times a day
-Give 2% of your income or more to charity
-Fast during the day during the month of Ramadan
-Go to Mecca at some point in your life
Anything else is fluff. Maybe that fluff is intolerant or violent (really it's more nuanced than that, some of it is and some of it isn't), but it's still fluff. The religion itself isn't inherently violent or intolerant. | 19 | 58 |
What predictions can the social sciences make with high certainty? | Apologies if the question is overly broad. I know many people criticize the social sciences for being too "soft" or "fuzzy". Where it that entirely not the case? | One prediction we can safely make in the child/youth/family welfare space is:
The earlier you provide a welfare intervention in the life of a person, and the life of the issues they are experiencing, the cheaper and more effective that intervention will be.
For example - best way to reduce youth crime is to find the early warning signs (like skipping school, early drug use) and support the young person before they commit serious crimes. It's more effective and about 50 times cheaper. | 55 | 62 |
ELI5: Is all electromagnetic radiation "both a wave and a particle" or is only light considered this way? | I always hear about "light acts like a wave and also a particle" but I never hear about other EM frequencies being described this way ("never" considering my limited exposure). Are light frequencies special? Or does all EM radiation behave both ways?
Edit: thank you for your responses. I was already aware that light is EM radiation; I simply never hear folks talk about "photons" outside of reference to visible light, hence my question :) | What we call "light" is simply the slice of EM radiation that our eyes can detect as color. As you make the waves longer, you get into WiFi and the various types of radio; as you make the waves shorter, you get X-rays and gamma rays. It's all EM radiation -- all photons -- so it's all the same from the perspective of acting like both a wave and a particle. | 32 | 17 |
ELI5: How exactly do vector graphics work? | Here's what I know. Unlike bitmap images, vector images don't pixellate when you zoom in on them. I guess that's because they aren't made of pixels. A friend of mine tried to explain it to me, but it went right over my head. | Basically, a vector drawing files a list of instructions - draw a line from point a to point b, draw a line from point b to point c. Fill the enclosed area with a color, and so on.
Then, when you 'zoom in', the computer - effectively - makes the line sharper to take advantage of the higher resolution. | 23 | 32 |
ELI5: Why is cannibalism detrimental to the body? What makes eating your own species's meat different than eating other species's? | Your own species meat is infected with diseases that can also infect you, by definition. (Conversely with other animals, some but not all diseases can be spread by under-cooked meat.) There are also some degenerative diseases that are spread by mis-shaped proteins, which you can generally only get by eating a human brain. | 4,959 | 5,224 |
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I believe that, in some cases, illegally obtained evidence should be admissible in court. CMV | I'm not saying that there should be no repercussions. If a cop wiretaps my phone without a warrant and discovers proof that I'm committing a crime, he should be reprimanded or fired. **However, that evidence should still be usable against me in court.** Just because it was obtained unfairly doesn't automatically mean it's invalid.
Similarly, the [fruit of the poisonous tree](http://en.wikipedia.org/wiki/Fruit_of_the_poisonous_tree) concept is ridiculous to me. If I'm wiretapped and the cop hears me say that I left a murder weapon in a particular location, and they find a murder weapon in that location, that murder weapon should be admissible in court. The flip side of this, again, is that the cop who wiretapped me in the first place should be reprimanded or fired. But the evidence itself is still perfectly valid.
In our current system, it is entirely possible for our government to knowingly allow a guilty person to go free because a piece of evidence is invalidated based on a technicality.
The [exclusionary rule](http://en.wikipedia.org/wiki/Exclusionary_rule) seem to me to be nothing but a tool used to help lawyers game the system. It's hard to imagine a rule like this being used to exonerate an innocent suspect, or at least, it seems like it would preferentially exonerate guilty ones.
**This opinion only applies if the "truthfulness" of the evidence is not compromised.** So, if the chain of custody on a piece of evidence is broken, and it's possible that the evidence was tampered with, that evidence should not be considered admissible.
When a search warrant is issued, it should be issued to protect the officer from repercussions; its existence should have no bearing on the validity of the evidence.
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It's possible that my understanding of the way these rules are applied in practice is not accurate; I'm not in any way a lawyer, and most of my understanding of these rules comes from either TV or Wikipedia. If anyone has corrections in this area from the real world I'll be happy to accept them. | Allowing evidence obtained in an illegal manner to be admissible in court would give law enforcement officers an incentive to break the law in an attempt to gain evidence. Even if the cop is punished for the illegal search (or whatever illegal action generated the evidence) he will still think he did the right thing because the bad guy got caught because of the illegally obtained evidence. Do you really want to give incentive to that kind of behavior and thought train? (that breaking the law was good here because the ends justify the means) | 78 | 96 |
GMOs- engineered genes in crops don't spread into the wild, into other species, do they? | If the engineered plant or animal can interbreed with a native (or natively-cultivated) plant or animal, the engineered variants can be passed to offspring, just like any other gene. A genetically modified organism is just like the non-engineered organism plus a tiny bit of DNA added or changed in order to add, augment or change some function - they aren't fantastical beasts with lions and eagles spliced together. GMO corn is still corn, GMO soybeans are still soybeans and GMO salmon is still salmon.
If no native species exists that the engineered plant/animal can breed with to produce viable offspring, or the engineered plant/animal is rendered infertile or otherwise isolated, no transfer into the environment will occur.
As far as whether they'll take over wreak havoc on the local flora and fauna - that depends strongly on exactly what was engineered (genetic engineering is only a technique) and if there were any impacts on organismal fitness - not all modifications are made with evolutionary fitness in mind, and some variants may be less "competitive" against their wild relatives. | 112 | 181 |
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ELI5: How do hostage negotiations work? | When they make "deals" with the hostage taker how much do they honor those deals? When I watched Captain Phillips the negotiator made all of these false promises and I was wondering if this is common practice. | I have a few co-workers that have done HNT training. The way it works is like this, the HNT tells the hostage taker what she can offer and tries to work out a reasonable solution. All people have basic needs, and the HNT will try to take care of those first. The start of talking someone down may go like this: Are you hurt? Does anyone need medical attention? If you or anyone is hurt, we can get them out and get you the medical care you need. Can you bring the hurt people out?
The next order of business would be safety and security. The HNT may ask: Is every one safe? Are the hostages safe right now?
Believe it or not, most hostage takers are not about to go killing the hostages, or even beating on them badly. Most of the time, the hostage taker has a sense of empathy and won't want to hurt people. A lot of times, the hostages are secured somewhere safe. Ensuring the hostages and the hostage takers are safe builds a stronger relationship.
Next, provide for basic needs. She may say: This could take awhile to resolve. Does anyone need food, water, or to use the bathroom?
Finally, she will work to resolve the situation. She will not make promises. She will not overstate her abilities or the strength of the hostages. She will also not refuse anything or say "no" to anything. She can, however, redirect the conversation. For example, if the hostage taker asks for a fully fueled jet airplane, an acceptable response would be something along the lines of: Let's get back to seeing how many people are hurt. We were working on taking care of those with medical emergencies first.
Skilled hostage negotiators don't have to make false promises because they don't have to make promises other than the ones they are prepared to honor. | 12 | 18 |
[Star Trek] In TNG, could any of the bridge crew be speaking another language, and we wouldn't know it, due to the Universal Translator? | I was just wondering this. Could Picard be speaking French through the whole show? Could Counsellor Troi be speaking Betazoid or whatever her home planet language might be? Or, do you think English became the universal language of Earth and diplomacy at that point? | Standard military protocol would call for all persons onboard to speak a single language while on duty.
This will ensure that, in the event of an issue with the translator, communication will not be hampered. | 25 | 21 |
ELI5: How can some watches be more accurate than others? | I don't know much about watches, but I remember reading some watches only make a few seconds mistake each day, whilst others have larger error range. Isn't there a mechanical system that keeps the thing automatic? How can that create errors?
Also some watches can remain accurate for decades, if one watch maker can do it, why can't other do it?
I guess I'm just confused as to why there are errors and if there are errors, why some brands have larger margin of errors.
Thank you in advance for your answers. | Quality control and tolerances.
In any machining operation your parts have tolerances. A tolerance is how far out of the specified dimensions the part can be. Very exacting tolerances get rapidly more and more expensive, as they require much higher quality of both manufacturing equipment and labor, and a quality control system that is willing to throw away potentially very expensive parts for being a *tiny* bit too big or small.
A mechanical watch with very tight tolerances will be very expensive to make, but it will be extremely accurate because you know to a very high degree of certainty *exactly* how all the parts interact.
A watch with loose tolerance will be much cheaper to make, but won't keep time as accurately because bits and pieces are going to be a little bigger, or a little smaller, or a little heavier than they should be, and in unpredictable ways. | 28 | 15 |
ELI5: What is the difference between waiting for the tea to blend with the water and blending it by force? | I know a lot of people let a tea bag subside in hot water and just wait a few minutes before drinking/sipping the tea. I myself just pull the bag up and down until the color of the water changes and sip away.
Is there any difference, and where does this habit come from?
Thanks in advance, and excuse me for any grammar or spelling mistakes. English is my 3rd language. | Tea has a mix of different chemicals inside its leaves, and some tea types add others (bergamot is added to Earl Gray, for example). When you process it and put it in a teabag, it takes different lengths of water soaking to bring all of those chemicals out. Some add a pleasant flavour, some (like when you let green tea soak for too long) add bitterness and aren't as pleasant.
By doing a quick dip and swishing around, you're only getting some of the right chemicals because the water hasn't had enough time to fully penetrate and rinse out the others. And depending on what type of tea you're making the extra force might help pull out some of the wrong, more bitter ones too, or create an imbalance in the taste (example: going too quickly produces too much "clove" flavour in a chai tea).
People steep tea - let it rest - so that the hot water can fully soak in and extract all of the right flavouring chemicals in balance, instead of just pulling out the initial ones that change the liquid's colour and maybe some of the wrong ones too. | 52 | 86 |
What is the reasoning behind a capital gains tax of 20% but income tax being >30%? | US-based situation, and I know income tax varies from state to state, but let’s assume capital gains of assets held long-term are taxed at 20% and income from salary is taxed at roughly 1/3rd of your gross pay check.
What is the argument for capital gains being significantly lower? Is it because this amount is already much bigger than income every year? To encourage investment instead of consumption? Belief that private allocation of capital is more socially optimal than govt spending? | As per the introduction to Chapter 9 - Investment, of *Advanced Macroeconomics, Fifth Edition,* by David Romer:
>The combination of firms’ investment demand and households’ saving supply determines how much of an economy’s output is invested; as a result, investment demand is potentially important to the behavior of standards of living over the long run.
Essentially, capital investment is the primary driver of economic growth. The view is that lower capital gains taxes provides incentive for higher levels of investment. That is an explanation of why a policy maker might want capital gains taxes to be lower. Is there a good reason for income taxes to be high?
From the same textbook, Romer says
>Both capital taxes and labor-income taxes distort individuals’ labor-leisure choice, since both reduce the overall attractiveness of working. But the capital income tax also distorts individuals’ intertemporal choices.
Romer's contention is that capital gains taxes are *more* distortionary than income taxes, since investments are just savings vehicles, and savings is just deferred consumption, they distort choices across time. | 53 | 111 |
ELI5: What is the significance of Prime Numbers? | Mathematically speaking, you can define all other numbers purely by multiplying prime numbers. So we don't actually need any non-prime numbers, as we could simply define 4 for example as 2x2. Or 99 as 3x3x11. Obviously this would make daily life a lot harder, hence the other numbers having their own names and symbols. | 56 | 91 |
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What should i know before learning to code? | I would like to learn how to code or how to program in general, but i don't know what are the most important things to have in mind before doing so. | Don't be ashamed of looking up "solutions" to problems. If you look at someone else's code and actually try to understand it, you'll learn a ton compared to someone who spends hours upon hours trying to figure out a solution on their own. | 41 | 19 |
What was the very first post-Newton experiment that hinted the universe wasn't as it seemed? | I suppose that Special Relativity was the big point where physics took a sharp turn away from Newtonian physics. But what was the very first precursor observation that suggested that the universe wasn't really just a "box containing lumps of mass that attract each other", and didn't behave in a way that common sense would suggest?
To put it succinctly, what was the first "weird" observation? | The Michelson-Morley experiment was important, but there were some earlier hints. The Fizeau experiment of 1851 was what influenced Einstein, more than the MM experiment. Thompson in 1881 noticed that it was harder to move fast charged objects than slow ones. The orbit of Mercury was realized to be anomalous in 1859. The discovery of x-rays in 1895 is often considered the start of modern physics, because it was one of the first hints that there was way more to be discovered, rather than just fine tuning and precise measurements. | 23 | 24 |
If Blue, Red and Yellow are the primary colors then why are Blue, Red and Green (RBG) used for generating colors in computer programs? | I really tried to google this, but I didn't see clear explanations on the difference. If I google RBG then I find posts which call these the primary additive colors, with green and red making yellow. I thought maybe my primary schooling was just old and color theory had changed a bit, but if I google primary colors for art purposes like painting, then it seems that blue, red and yellow are still the primaries for, say, mixing paints. | Our eyes contain receptors sensitive to red, green, and blue light. There is some overlap between them at the edges of their sensitivity spectra. We see yellow when our red and green receptors are both stimulated. This can be caused by light wavelengths in between red and green stimulating both receptors, but a mix of red and green light will also stimulate both receptors. Hence RGB for light-emitting screens.
Paint and pigment is based on reflecting *and* absorbing light, rather than directly mixing light. This leads to different effects from mixing pigments vs mixing light. You're not only combining the reflected light bands, but also cancelling them out via absorbed light bands.
Edit: why yellow and blue make green.
Yellow paint reflects red and green light while absorbing blue. Blue paint reflects blue light while absorbing more red light than green light. Red-absorption from blue paint cancels out red-reflection from yellow paint, and blue-absorption from yellow paint cancels out blue-reflection from blue paint. Green-absorption from blue paint doesn't quite cancel out green-reflection from yellow paint, so the resulting paint mix is green. Replacing blue paint with cyan paint will result in a brighter green, since cyan paint mainly absorbs red while reflecting blue and green. | 6,892 | 8,527 |
ELI5: The Tribal sovreignty/Indian reservation system in the US | Hi everyone. As a Brit this has always confused me somewhat. How does the Tribal sovreignty system work in the US.
Adding to that, how does one prove that they're Native American to be able to claim such rights. Is there a certain % DNA that needs to be Native American?
Thanks, genuinely curious and interested in finding out more. | Okay first of all it's important to mention that it differs from state to state and tribe to tribe. The reservation system is more or less an effect of the conflict early setters had with the local residents.
Basically the American Indians are sort of duel citizens, one of their tribal nations and the United States. Under U.S. laws this is referred to as domestic dependent nations. (But not all the time)
This allows the Tribe to have different laws then the state that they are in. This allows them to have local courts or Tribal courts that may maintain criminal jurisdiction over the member of the tribe. But the Indian Civil Rights Act placed limits on the level of punishment to a year in jail or $5,000 and has no jurisdiction over non Indians (Again depending on state.) Major crimes may bypass the Tribal court systems and go with the federal court.
The main advantages to this system come from the ability to bypass state regulation involving hunting, fishing and gaming. This allows some Indians to have Casino's on their land, but not in all states. And it allows them to hunt with out a license as they are beholden to the tribal government and not the federal government.
Again this all depends on state, and tribe. Some states have extremely different cultures, and some are basically just a normal USA town with a different form of town council. Almost half of Indian are married to white people for instance.
DNA wise it's an extremely small amount and assuming you keep up the paper work, there are people that are 1/64 who still claim to be Indian and their 1/128 children will be Indian as well.
| 12 | 19 |
ELI5: Why do humans like to watch other humans dance? | One theory is that dancing is a way to demonstrate bodily symmetry. Symmetry is one of the main criteria we use in determining beauty, as it can be a decent indicator of good genes and good nutrition, both desirable in a mate.
So it taps into primal mating urges far older than civilization. | 26 | 58 |
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ELI5: In weightlifting, why is it, that the relation weight/repetitions is not even close to proportional? | So I have been doing semi-competitive weightlifting since I was 16, but it just now occured to me, that the relation between the weight on the bar and the amount of reps, that one can do with that weight is neither linear nor proportional.
Say I can do 440lb for 2 repetitions, that means I will probably be able to do 470lb for 1 rep at best, which is not even close to 880lb (440*2).
Furthermore, if someone benches 225lb for 1 and I can bench 450lb for 1 I am factually twice as strong as that person. However, if a person benches 225lb for 5 repetitions and I could bench 225lb for 15 reps I wouldn't even be close to being twice as strong.
Why is this? Given that physically W = m*g*h, with both g and h not changing, I need the same amount of force to lift a weight twice than I would to lift a weight that is twice as heavy once. | You're confusing "force" (N, Newtons) and work/"energy" (J, Joules). The force required to bench 225 for one rep is the same as the force required to bench 225 for a hundred reps: the weight is exerting 225lbf=1001N on you so you need to push with slightly more than 1001N to start it moving up on the concentric part of the lift, and then slightly less than 1001N to gently bring it back down on the eccentric part of the lift. It doesn't matter if you repeat this process for endless reps, the forces required are the same for each rep.
In your example above, if the max force you can exert is 470lbf, it doesn't matter how many reps you can do at that weight... The 880lb bar will be pushing down with 880lbf and you'll be pushing up with 470lbf and nothing will move. Even if you could magically summon up 881lbf, you would still probably fail the lift because human muscles get tired quickly and peak force production quickly drops. That's why bar speed is important.
Energy does scale linearly as you suggest: two reps moves the weight through twice the distance of one rep, so the number of calories burned is double, but this isn't really a concern for strength lifts.
(Btw, you used the formula for "work done on an object", which is technically always 0, since the weight ends up in the same position it started from. But that's not what we're interested in here.) | 235 | 393 |
[Magic School Bus] Is there a strong educational benefit to risking the lives of ones students in order to give them practical examples of random bits of trivia? | I'm a state Inspector and having observed Miss. Frizzle and her class shrink down and enter a sink to discover where municipal water goes does seem interesting, however two children nearly drowned, one was traumatized, and no one learned any math today. | When what you're learning is a matter of life or death, those are the lessons you *never* forget.
The kids are never in any real danger - the Friz is in full control. She just lets them think they could actually be harmed in order to drive the lessons home. She's some sort of 8-dimensional being and/or a wizard.
Parents were fully apprised of her teaching style and they signed waivers too. It's their fault if they didn't fully read the full document or thought it was a joke. | 18 | 17 |
Is there any herbal medicine that has clinical evidence about its efficacy ? | Modern medicine is often based in remedies found in nature. Aspirin is famously derived from the bark of the willow tree, ginger has excellent anti-nausea properties, vitamin c found in citrus fruits can help your immune system and stave of scurvy, and many more.
While the idea that herbal medicine can cure ills better than the modern equivalents is clearly misguided, but things based in herbs and plants are well document to be effective, especially for relatively minor complaints. | 69 | 64 |
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What are the most reputable books about art's role in society, especially in affecting social change, promoting humanist ethics, and help people cope with existence? | John Berger's *Ways of Seeing* explores how paintings reflect their age of origin, and how the way we see them is dependent on our own age.
Walter Benjamin's *The Work of Art in the Age of Mechanical Reproduction* suggests that the modern industrial age has transformed the role of the arts; Benjamin gave several arguments throughout his career regarding how art should be re-transformed to cope with the modern age.
Susan Sontag's *Regarding the Pain of Others* is an essay on photography that aims to answer a question posed by Virginia Woolf in *Three Guineas*: "How are we to prevent war?"
Friedrich Nietzsche's *The Birth of Tragedy* is an analysis of the arts in Ancient Greece, with the aim of showing that Greek tragedy was a balance of the 'Appolinian' and 'Dionysian' ways of life, allowing the Greeks to experience existential fulfilment.
Theodor Adorno's *Minima Moralia* is a book of aphorisms, many of which are about various artworks, which explores existential themes and the notion of 'the good life' in a post-holocaust world. | 13 | 15 |
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ELI5:What’s the purpose of long words which have short, simple equivalents? | In English, words do not need to have purposes. You cannot take a word to court and have it banished for shiftlessness and vagrancy. However, writers can have a purpose for using particular words. Often the purpose for using longer words is clarity and precision.
Short words tend to accumulate a lot of different meanings. "Have" can mean "possess", "obliged" (or "required", or "must"), or just be a helping word to change the tense of a verb. "Used" can mean "formerly", "accustomed", or "utilized". Having too many short, simple, but ambiguous words together in the same sentence or paragraph can render the entire thing ambiguous and opaque. This is particularly the case where the intended audience includes people with limited experience of English. While the words might be short and simple, figuring out what they mean through context is not.
There is a famous joke/pun:
> Time flies like an arrow.
> Fruit flies like a banana.
This is based on the ambiguity of both "flies" and "like". If it were written like this:
> Time propagates similar to an arrow.
> Drosophila appreciate a banana.
then there would be no ambiguity. There would also be no humor, but sometimes ambiguity is no laughing matter. | 25 | 22 |
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[Star Trek] Assuming that it remains a thing, could other Federation species compete in the Olympics? What about foreign species like Klingons? | Just as male and female humans are good at different things, all the different species are good at different things. Human men dominate at most sports, and klingons would dominate them at most sports. Having them play against each other wouldn't be very sporting. | 20 | 45 |
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ELI5: Dark Matter | What is it? I understand that current believe is that most matter in the universe is dark matter and only about 4.6% of matter consists of atoms(quick wikipedia lookup). However nowhere do I see explained what dark matter actually is. I see theories about it's existence but still, what is dark matter? | We can calculate how gravity will affect an apple, or the Moon, or entire solar system and equations work, orbits are predictable, ect ect. When we look at galaxies and clusters and very big objects and try to calculate how they should behave we get wrong results (stuff was spinning at wrong speeds). So either laws of gravity is wrong, or not fully understood, or there is additional something in the universe that affects it. We can't see it, can't catch it, but it must be there, because gravity is affected by it.
Best we can do right now is strap a placeholder name to it, throw a couple of equations explaining it and call it a day.
TL;DR It's either some sort of exotic matter we can't see, or quality of space we do not know of yet, or our inability of comprehending gravity. | 15 | 20 |
Why am I conscious and aware? | If I am a simply a product of evolution and time. Why am I aware and conscious at all? For example, the universe existed when I wasn't conscious, so why did i suddenly go into existence? Why can't there just be a MaxCL, but my current consciousness didn't exist. Like all our actions can be explained by the atoms, so my consciousness or awareness isn't necessary AT ALL. I think everything is cause and affect but I am freaking conscious for some reason. Sorry I couldn't word this better, I'm having a midnight crisis. I hope you understand my question! | Good questions; one answer is that certain physical configurations (I.e. Your brain) give rise to minds and so consciousness as well. But why these and not others? Well, that's the problem isn't it?
The whole "why did evolution give rise to consciousness" is a really good question because there doesn't seem to be any reason why we need thoughts to survive; maybe our theory of evolution is missing something, maybe there's a reason why subjective experience is adaptive, or maybe consciousness isn't natural at all.
There's a lot of literature about the topic, but philosophical zombies are a pretty good place to start regarding "conceiving a world where you're not conscious." | 11 | 21 |
ELI5:How were battles in wars 'organised'? | My guess is that leaders would message one another saying "we are fighting, meet here at this time" or whatever. So how did it happen? | Leaders didn't coordinate to decide when to fight each other. In most wars, both parties have objectives - locations that are important to control for strategic reasons. Maybe a town has a bridge across a major river, or a manufacturing plant that makes weapons, or a fort controls access to major shipping routes.
Army A wants to take these things from Army B, because Army B will be weaker without them. Both armies send scouts to figure out how many men the other army has, where the armies are camped, and how fast they can move. Army A's scouts report that Army B only has a few men guarding an important town, so Army A's leader decides to march for that town. Army B's scouts see that Army A is moving toward the town, so Commander B moves a large force to try and intercept them before they get to the weakly-defended town.
Now, a few things can happen. Army A's scouts may see the large group from Army B and move back to try again later or go a different way. They might decide to engage Army B if they think they can win the battle, because then they have no opposition to taking the town. It's also possible that they get to the town earlier than Army B thought they would - they take it over, and control it, and Army B then has to re-take it from them.
Battles happened because both armies were trying to prevent the other from controlling important areas. | 42 | 30 |
Ethics: Would you save a person's life or a museum? | Hello folks,
Just heard the sad news that [Brazil's National Museum caught fire tonight](https://www.bbc.co.uk/news/world-latin-america-45392668). It could have been the Louvre, the British or the Metropolitan.
That made me wonder....
In the hypothetical scenario in which one could save a person's life or one of these museums from destruction, what is the ethical route to go along and why?
Was this kind of dilemma ever tackled by philosophy?
Thank you! | This seems fairly straightforward to delineate from the main schools of ethical thought.
&#x200B;
From a consequentialist perspective, it seems simple enough to say that the ethical thing to do would be to save the museum from destruction. If you apply even a very basic utilitarian approach, it stands to reason that the value of one human life is substantially less than the value of a collection of timeless works of art and culture. The moral calculus is such that these objects and collections are far more likely to bring greater happiness to a greater number of people than any one human being could ever hope to do. Whether the person is a complete stranger, your mom, or even some of world renown, at the end of the day they are inherently replaceable, which is something that cannot be said for priceless cultural objects.
&#x200B;
From a deontological perspective, it seems as though our duty to the preservation of life is likely going to supersede any consideration of the intrinsic value of art and culture. Many duty based theories tend to include unbiased morality and some mention of natural rights. A common natural right is, of course, that of a right to life, which makes it an obligation for the person in this scenario to save the person at risk. After all, we generally do not have a duty to put ourselves in harm's way for the preservation of art, so it stands to reason that art would then not take precedence over the life of a human at that point.
&#x200B; | 14 | 46 |
How can you exclude results from the methods section when some of the early results are needed to understand subsequent methods? | Basically it seems hard to separate them when your workflow followed a particular route. Specifically: I tried X (a method) out, Y (a result) was what I found, based on this result I decided to do Z (a method).
This makes it really difficult to untangle things into discrete “methods” and “results” sections.
Help would be really appreciated! | This may depend on the standards of your field, but one thing to keep in mind is that a paper is not necessarily meant to be read linearly. So one way to approach this is to use results to describe the narrative, giving just enough of a description of X and Z to make sense contextually, and to use methods to delve into the details of the methods. So as an example:
**Results**:
I tried method X (see Methods section 1 for details). We found Y.
Based on this, we tried method Z (see Methods section 2 for details). We found ...
**Methods**:
Section 1: Method x.
Section 2: Method z | 75 | 61 |
CMV: Being Pro-Gun and Pro-Gun Control is actually the smartest and most realistic view. | To start I live in California, and I tend to think I am ideologically liberal and fiscally conservative.
I love gun's and think you should be able to own a semi or fully automatic rifle of what every caliber you like, there should not be any restriction on magazine size, suppressors or optics and you should not need a bullet button or anything like that.
But to be able to have that freedom to own those types of firearms you must complete Xhrs (maybe 100 or something) of firearms training. You need to register all firearms no matter how you purchase them. And background checks should include mental health evaluations that also need to be done again every 2 or 3 years.
I'm not saying this is the perfect solution, but it seems the vast majority of liberals tend to be of the mindset that guns are bad and no one has a need for any firearm except for a hunting style rifle/shotgun or maybe a hand gun but no AR style firearms.
Conservatives tend to think that the should have any type of firearm they want and that there should be hardly any regulations at all about how they purchase firearms, and should not have to register their firearms at all.
"A well regulated Militia being necessary to the security of a free State the right of the people to keep and bear Arms shall not be infringed" (I took out all the comma's) Conservatives tend to only read the last part from 'Right to bear Arms' onward.
The whole notion of well regulated is completely ignored.
I cant seem to grasp why the vast majority of people on the left and the right cant see that neither of the all or nothing types views will never work and honestly don't make that much sense practically either.
I also don't think the gun/car comparison isn't that far off. Treat firearms like a more regulated drivers license (The DMV is a joke and it should be much more like Germany but that a different topic all together) as long as you get all the requirements license, insurance etc you can buy any car you want. No one needs a 800hp car and they are usually far worse for the environment but you can buy them no problem.
P.S. sorry for all grammar and spelling errors, and I look forward to you all helping me understand your views and possibly changing my mind.
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> *This is a footnote from the CMV moderators. We'd like to remind you of a couple of things. Firstly, please* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | "Well regulated" means "properly functioning" in the period parlance. It was a phrase used long before and for a century after the founders wrote the words.
How about before someone can vote, they have to
>complete Xhrs (maybe 100 or something) of [voting education]. You need to [let local government know how you voted]. And background checks should include mental health evaluations that also need to be done again every 2 or 3 years [or you lose the right to vote].
If you think those requirements would be over the top for voting, then how in the world would you apply that standard to an activity that the constitution clearly says "shall not be infringed"? | 27 | 20 |
Eli5: Why does the area of insect bites turn warm and hard? | When your body detects injury it widens the tiny blood vessels around the injured area to let in infection fighting/body repairing cells.
These additional cells causes heat, hardness because of the increased pressure, and redness because of the blood.
A lot of bites like those of mosquitos inject a little bit of saliva. The body treats that saliva ust being there as an injury, so it might be going a bit overboard with the response. | 38 | 31 |
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CMV: Harry Potter has an awful magic system which severely weakens the plot | **READ THIS**
~~Hey folks this is a really cool conversation, I am enjoying hearing your points of view! But I have to go to bed now, shit's late.
I will pick up on replying to more of these and continuing this sometime tomorrow after my lectures~~
EDIT #2:
Holy shit this has exploded, I never expected this to get as big as it has. I am slowly working my way through the different arguments.
It seems very evident that I failed to highlight the main point of my argument, as people are diving into semantics arguments focusing on specific side points to the overall message.
The basis of what I am arguing is better explained [here](https://www.reddit.com/r/changemyview/comments/5p1lo2/cmv_harry_potter_has_an_awful_magic_system_which/dcnscwx/?st=iy61scrc&sh=0f2eab35).
EDIT #3: Everyone and their grandmother is getting held up on the wandless magic point, referencing pottermore and the later books where that is established, but that was just a symptom of the overall issue I have with the series which is better outlined in that comment and [this one](https://www.reddit.com/r/changemyview/comments/5p1lo2/cmv_harry_potter_has_an_awful_magic_system_which/dcnt1fz/?st=iy62qdsp&sh=cd2cbe73) as well (Last half of that comment).
There may be arguments that convince me already on the post, but due to how complex these posts are its taking me some time to get through and evaluate them all.
Thanks!
---
Hey there, so to start things off, yes Harry Potter is a good story, I am a fan of the book series overall, but this issue is a major gripe for me.
Second, I have not read the books recently, this is a thought holdout that I've had for years.
----
I love stories that set out the rules for a magic system, and then navigate their plots through that system while keeping it consistent.
A couple examples of a consistent magic system are Eragon and The Kingkiller Chronicles. On the macro scale both of these systems are very similar, the magic that happens is rooted in an energy balance.
In KC, you can light a cigarette by taking energy from your own body, or a nearby fire, etc. which will then cool as a result. And the further away something is, the higher the cost.
In Eragon, all actions require a similar energy, its a bit more ethereal than KC, but still has very defined limits. Users can't do very much before they are exhausted, so they need to draw on sources of power such as other people, or stored potential energy that was previously harvested.
The point is that, these relationships are established early on in the book series, and while characters refine their abilities, and learn more about the magic system, the base rules continue to apply.
---
In Harry Potter, the rules are laid out in some of the initial magic lessons, but as the series progress, almost everything that has been established gets thrown away.
Even worse, in many cases whole plot devices are reliant on just some new form of magic that the reader had no idea was a possibility.
- Exceptional spell pronunciation and precise wand movement is explained to be essential for a spell to function at all, but then later we end up losing the pronunciation and wand movement entirely. Magic can just happen wordlessly and without a wand.
- There's essentially no limit to a magic users abilities once you figure out a spell for the first time. You could cast Avada Kedavra all day long.
- Magic detection is entirely inconsistent. They can use the "trace" to detect *any* magic from someone underage *anywhere*, but can't at all tell when someone in the middle of the Ministry of Magic in under a Polyjuice potion? What is this huge magic detection network that allows the "trace" to work? How is it not being used for other things?
- Spells have a mind of their own, ala Accio and Crucio
- Incredibly overpowered items like the Time-turner effectively break the universe
I remember having other examples but it has been a while since I read the books.
(EDIT: Bolded this for emphasis, this is the thesis of my argument.)
**In summary,
to me, it feels like JK wrote herself in to corners fairly often and then had to default to "Because magic" as the solution. It really irritated me when I read the series for the first time, and I have never been convinced otherwise by friends when Harry Potter gets brought up.**
CMV
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> *This is a footnote from the CMV moderators. We'd like to remind you of a couple of things. Firstly, please* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!* | Wands and words are the tools to help guide a learning student into doing the right mental things to make the spell happen.
Sort of like writing - when you are learning to write, you begin to learn on those big pieces of paper with three lines in order to form the letters into words that are readable. You practice with precision. To write the letter lowercase d you make a perfect circle halfway up to the dashed line, and an absolutely straight line.
That is needed until you get the muscle memory down. Then you graduate to standard ruled paper.
Some people who have an aptitude become calligraphists, but those folks are rare.
Many things are taught this way. Learning Musical instruments. etc.. etc..
It's not the wand or the words that make the magic, those are the tools to lead you to do the right thing mentally. The focus on precision is just a teaching tool for young kids.
If you are good, or have an aptitude, you can be a bit lax with the wand and the words.
If you are exceptional, you can eschew them entirely.
Harry Potter is, at first, about the school experience. And practicing such things with precision is something that is done in elementary schools. Later on, the precision does not count as much - it's only the results that count. | 584 | 2,051 |
ELI5: How did the * become the symbol put after a word that has been corrected in a typo? | Asterix denote footnotes* which add clarification to something already said. You're supposed to have the * before the correction, and that was originally fairly common, although for whatever reason it's since migrated to after the word.
*You know, these things | 34 | 62 |
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Need help with academia lingo | New PhD here. I've been a nurse in the clinical setting for 8 years and as I start looking at getting into academia I realize I am somewhat ignorant on terminology. What exactly does adjunct mean? Is that the same as part-time faculty? I know the basics about tenure vs. non-tenure-track, but I'm more curious to understand how non full-time faculty works. I would greatly appreciate some clarification. | Adjunct means that the university is associating with you on a short term contract. Sometimes the contract is for pay (like to teach a class) and it can also be used for affiliated people who may do some collaborative work at the university for zero compensation. (Usually a professional courtesy for advisory roles) | 15 | 16 |
ELI5: What is preventing blue states from enacting single-payer/universal healthcare? | Most US states have constitutions that would permit this, or at least have a mechanism for amending their state constitution to permit this.
What's preventing it is lack of desire to raise taxes or regulations in just one state, because that might drive businesses or wealthy individuals to move to an adjacent state. By contrast, if *all* states do something, that risk is lower. | 29 | 29 |
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Why does wood not decay/rot and stay strong, when other natural plant/animal matter rapidly decays? | Wood can decay and weaken, depending on the environmental conditions.
One thing that ruins wood quickly is constant humidity and temperature changes. Ever seen an old fence or deck that's all warped and cracked? In many cases, that's because the constant inflow and outflow of water is ruining the cell walls. The waterlogging of the wood causes structural changes, followed by the collapse of the material when the water leaves. This is why conservation is so vital for waterlogged wood from an archaeological site.
Keep wood in good environmental conditions, and it can last for a very long time, as you've noticed.
Other organics can survive as well, if given the right conditions. Leather and bone can both survive in good shape for centuries, if proper conditions are met. Organics (of many kinds, including textiles) are frequently found on shipwrecks, especially where they've been buried in mud. This is because they reach an equilibrium with their environment, and because no microorganisms are eating them (the mud prevents oxygen from reaching the artifact).
When *not* in the right conditions, organics are frequently eaten by animals or microorganisms, in addition to the physical weathering processes. | 84 | 108 |
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ELI5 what is a country's economy, and how or when does it collapse? | The economy is the sum total of all goods produced, bought, and sold within a country. It is typically measured using an index called the "Gross Domestic Product," which is the total value of goods sold in that country in a given year.
An economic collapse can mean many things. It can mean a significant drop in GDP (Economists say that two consecutive quarters with a shrinking GDP constitutes an economic recession.) It can mean a spike in unemployment. It can mean a significant drop in the value of the country's currency.
As to why an economy collapses - many reasons. Droughts, wars, out of control real estate speculation, revolutions, global pandemics... | 21 | 29 |
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ELI5: Why can we see better in the dark with our peripheral vision? | Our eyes have two types of receptors in them that interpret visible light into what you see, called rods and cones. They are spread over the retina, the inner back surface of the eyeball, but they are not spread evenly. Rods are better able to detect low light, so they are responsible for seeing in the dark. Cones are better able to detect colours in well lit conditions, so we use them most of the time. There are mostly cones near the middle of the retina, and mostly rods near the edges, which is why you can see better in the dark with your peripheral vision. | 30 | 27 |
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Is it a bad time to be in higher education? | There are obviously a million personal factors that go into deciding to get a undergrad/master’s degree, but from a broad economic standpoint, is it bad to enter higher education in the US right now? If we are entering a recession (as a layman, idk if we are), is it a good idea to get a degree in the meantime or to wait it out and save up a bit with a random job for a couple years before going back to school? | From a labor economics perspective, when the economy contracts is the best time to invest in human capital like going back to school. Mainly because the opportunity costs of education are lower. Say you can find a job paying $60k a year. Your opportunity costs for going to school are the $60k plus the costs of education. If the economy enters a recession and that $60k job now only pays out $50k, your opportunity costs are $10k dollars less per year than before. Another thing to consider is that students who graduate during a recession earn less over the lifetime of their career. That’s a hard one to predict because no one knows what the economy will look like in 2-4 years down the road, but because the economy is changing rapidly, it will be different from what it is today. | 53 | 41 |
CMV: It should be illegal for US Senators or Congressmembers to hire a tax accocuntant or tax attorney to do their taxes. | These people are responsible for writing the tax law in the first place. That's an important part of thier jobs. If they can't do it without help then either, 1) they aren't competent to be writing tax laws, and they should be fired, or 2) they are writing laws that are far too complex, therefore, they are just doing a poor job and should be fired.
If they try to make the argument that they *could* do it but it just takes too much of their valuable time, see #2 above. Everyone's time is valuable. Make simpler tax laws.
edit: \[Thank you to everyone who posted comments & questions here. This was my first attempt at posting on CMV and i'm happy with the result. It has helped me think about my views on this. Clearly I admit "make it illegal" is a step too far. My feelings are rooted in two basic problems, the tax code for individuals is far too complicated as a result of being incrementally modified over years and years of tweaking. The results are 1) is wastes the time of everyone who files taxes 2) it makes it easier for unethical filers to hide things. If members of congress did thier own, i think this would incentivize them to re-write from scratch and simplify the tax system.
I have some homework to do... to study more about the delta system on CMV. I'll make sure to do that before the next time I post so that i can hand out some deltas to deserving comments nest time.
Thank you.\] | Do surgeons perform surgeries on themselves?
There is a big difference between drafting tax legislation and utilizing tax legislation. Drafting tax legislation is a highly political process, while the preparation of taxes is a highly technical process. These two processes require different skill sets and that is why politicians need to hire the respective individuals to assist them. Additionally, there is also a difference between a tax accountant vs. a tax attorney as they are not synonymous occupations and consequently require different albeit similar skill sets and certifications. | 33 | 18 |
ELI5: How are humans so much more energy efficient than robots? | A human can eat two 1000 calorie meals (around 2 KWh) and then move around all day and run its brain and all other systems. A robot needs a lot more energy to perform the same tasks even if it's plugged in and doesn't need to carry a battery. There are sophisticated robots now that are as agile as humans if not more (like Boston Dynamics' Spot) but they need 2 KW every hour just to do what a human can do with 2 KW in 16 hours or more. Why do robots need to eat so much?
Edit: Correction, Spot has a 605 Wh battery which is good for 90 minutes of active operation. | Human body efficiency is usually quoted at around 20%, meaning 80% of energy input will be lost to waste heat, while 20% will be converted to useful work, as defined by the task. A brushless DC electric motor will usually end up between 70% and 95% efficiency - let's go with 80%.
A human could convert 2KWh of meals into 0.4KWh of work. A purpose-built robot for a task solvable by electric motors could convert 2KWh of electrical energy into 1.6 KWh of work.
Consider the possibility that some of the numbers or assumptions in your question might be faulty. | 31 | 27 |
CMV: Secular values and ideals, not Christian ones, are to credit for American exceptionalism and the success of "the West" more broadly. | Conservative pundits like Stephen Crowder, Ben Shapiro, and Denis Prager claim that what makes America, and "the West" more broadly, great are Judeo-Christian values.
However, individualism, civil liberties, democracy, science and reason... All the ideals that make America as great as it is today are thanks to the Enlightenment, which was largely a secular movement. Many of the founding fathers (Washington, Jefferson, Franklin, Madison, Monroe) were deistic, meaning they were not "Christian". Jefferson literally wrote his own version of the Bible excluding all the supernatural bullshit and miracles.
And if anything Christian fundamentalism has held our country back, and continues to do so to this day. People that think the earth is flat, that evolution isn't real, that bomb abortion clinics, that create gay conversion camps: they cause a demonstrable harm to our society.
Another thing that throws a wrench into conservative notions of Christian ideals and American exceptionalism is that Eastern societies were far more advanced than the West prior to the Enlightenment. Our numerical system was developed by Hindus, and popularized by Arabs. Advancements like ink, paper, gunpowder, were all made in China. Baghdad, a Muslim city, was a hub for scientific and philosophical advancement. My point is that the Christianization of a civilization isn't correlated with the greatness of said society, and if anything it is negatively correlated. Another fact that exemplifies this is that South America is arguably more Christian/religious than the US and other European nations, but far less successful.
I guess I just don't understand where conservatives get this idea that Christianity and its values are what make America, and the West great. | I think there were many important secular influences on our country, but the american view of civil liberties was influenced a great deal by John Locke.
One of the premises of Locke's second treatise was that all men were made in the image of God. This particular Christian influence was one of the sources of the idea that all men are created equal.
This obviously wasn't universal. Other christians, who disagreed with Locke, used their faith as a premise in arguments for a divine right to rule. | 665 | 4,939 |
ELI5: Why does squinting help you see better when you don't have your glasses on, but doesn't overcorrect when you do? | From a previous ELI5, I know that squinting helps you see better because you flex your cornea which helps bend the light to get a better focal point, but shouldn't squinting when you have your glasses on/contacts in cause an overcorrection as if you are wearing an overprescribed pair of glasses/contacts? | >I know that squinting helps you see better because you flex your cornea which helps bend the light to get a better focal point.
This isn't accurate. Squinting helps you focus because it reduces the size of the hole light has to get through to reach your retina. The same way a camera obscura works, or why reducing the aperture of a camera increases the depth of field.
This is also one reason you can focus better in bright light, your pupil is smaller. | 37 | 44 |
ELI5: Why do the clocks on all my devices fall out of sync? | Had a power cut three months ago. Set my oven, my microwave and alarm clock to match the time on my phone. After setting them they would have all been within 1 minute of each other roughly.
Three months on, at the time of writing this, my phone reads 10:10, oven 9:56, microwave 10:02 and digital clock 10:11. | The clock in each machine is designed around a resonator - a small device which vibrates and its vibration is measured and counted to keep time. This is much like the pendulum in a clock.
Now these things are precise. Higher quality ones can get very precise. They are not, however, perfect, and every one will be cut slightly different. A different cut means a different frequency, and a different frequency means that one will count faster than another. | 49 | 31 |
I don't understand: "Explain why a computer cannot solve a problem for which there is no solution outside the computer" | I've been trying this phrase: Explain why a computer cannot solve a problem for which there is no solution outside the computer. It's an assignment by my prof, but I can't even begin to understand it. Does "outside the computer" mean that if humans for example (who are outside of a computer) doesn't have a solution, then the computer wouldn't be able to have a solution? Does it mean that a computer needs to have all the tools and processes available to it in order to solve the problem at hand?
I see on YouTube that there situations in which a computer cannot give an answer about whether a program will have a stopping point or if it will keep going in an infinite loop..Is that what this question is asking? Someone please give me some insight. | I would interpret it in one of two ways: Either there is no solution, as in there has not been a way discovered (An algorithm) to figure it out. In that case, a computer can also not figure it out, as it requires humans to write algorithms to solve the specific problem.
The second case is how you interpret it: There are some problems that are just not computable. As an example the famous Halting problem. Read up on that. Those are problems for which we humans have no algorithm, as it is literally mathematically impossible for one to exist.
These would be the two ways i interpret it. | 50 | 45 |
Did Immanuel Kant Consider Women and African Races As Irrational ? | Rationality is a pretty common theme in Kantian ethics however my question is according to Kant's defination what exactly counts are being rational ? What makes a person rational ?
Secondly my question is that did Kant consider women and non-caucasian races as rational beings ? I heard from a feminist defender once that Kant didnt consider women or Africans are rational beings and saw them as intellectually inferior. Is this true ?
Im not a Kantian however i am researching on Kantian ethics and I really wanna know what Kant's views were on rationality, race and gender ? | I can’t speak of Kant’s thoughts on women, but there was a great article written by Pauline Kleingeld about Kant’s racism called “Kant’s Second Thoughts on Race.” (In the article she claims that Kant’s conception of women does not undergo the same change as his views on race).
In it she argues that, originally, non-white races, according to Kant, did not hold the same level of mental capacities, but that they, by status of their humanness (which he did think other races were human) belonged to the category of Vernunftwesen (rational being). He initially posited a racial hierarchy between races, but as Kleingeld mentions, toward the publishing of *Toward Perpetual Peace*, he seems to have reasoned himself out of his former views due to his ideas of cosmopolitanism. He even denounces chattel slavery in that same work. There are still unresolved issues on the topic, such as why he endorses an inherently racist book on physiology, but the article is a very worth while read.
Edit: OP not sure if you downvoted me, but did you somehow want an article that argued that Kant was a racist and could never change his mind on the topic? There’s tons of literature out there that tries to cancel Kant—I’m offering a nuanced view. | 45 | 18 |
eli5: why does glass absorb infrared and ultraviolet light, but not visible light? | It has to do with how light interacts with matter.
To absorb light, you need to have things work just right. You may have heard that light is quantized, what this means is that it only gets absorbed in specific chunks, one photon at a time. And all the energy of that photon has to go somewhere.
It turns out there are a few different places for that energy to go, and since each color of light has different energy, those different absorption mechanisms affect the colors differently.
Ultraviolet has the highest energy, it’s absorbed into the electrons in a material, kicking them up in energy or ejecting them from the atoms entirely. Infrared light is absorbed into the vibrations of the atoms and molecules in a material. For glass, visible light isn’t high enough energy to be absorbed by the electrons and too high to be absorbed as a vibration. Remember, it’s all or nothing - you can’t absorb half a photon. It gets a bit more complicated since you also have to absorb the momentum of the photon, and not matching the quantized momentum kick will lead to the photon not getting absorbed either.
Different materials have different thresholds for these absorption methods, and a huge difference is whether things are metals or not. Metals have completely different architectures for their electrons, but the basic concepts of “need to absorb a whole photon” still apply. | 1,717 | 6,424 |
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What do we really get out of water? | I was just thinking about it, and realized I don't know what exactly we get from water. That is, I can see cells taking the bits of H2O and putting it somewhere wherever water needs to be, but I have no detailed concept of what our body does with it. Can someone explain please? | Well a lot of different ways. Water is used to cool us down (sweat). It's used in certain reactions that take place in the body (cellular fluid), it's used to dissolve and transport things through the body (blood). It's used to dissolve things that need to be removed from the body (urine). A whole lot more too! | 17 | 24 |
Starting a research group after achieving financial independence | I have a Ph.D. in Computer Science, graduated in 2012 from a U.S. institution. I've been working in the tech industry in machine learning and doing well, so I expect in the not so far-off future to achieve my "FIRE" goals and be able to live modestly off my investments.
I miss the academic world and I'd like to rejoin that community and contribute my ideas to the research world, but I'm not sure the best way to go about it. My primary goal will be to work on my own research projects (i.e., I'm more interested in research than teaching, although I'd enjoy giving special topics seminars to interested students) and to build up a community of like-minded people to work on problems of interest with me.
Does anyone have examples of people doing something like this successfully? I don't think it makes sense for me to try to get a tenure-track job since these seem to favor new graduates, and I won't need the salary. But I would like to be associated with a university just to be in the right community to discuss ideas (in my case, I'm interested broadly in human-style AI (AGI) as opposed to mainstream machine learning).
In an ideal world, somehow I would raise the funds (e.g. through external grants etc) to run my own research group, but again I don't know how feasible this is unless I'm a tenure-track professor as opposed to a crazy independent scholar on the fringes of some academic institute.
Looking forward to suggestions here. Thanks! | Can’t you just apply as an adjunct faculty or research faculty at a university? I’m not sure if you can have your own research group in those roles though. Maybe starting a company would be a better fit. | 48 | 115 |
ELI5: What is happening to your eyes (& brain) when you are thinking about something & you stare into the distance, seemingly oblivious to what is happening in front of your eyes? | I don't know if I'm explaining this properly.
I'm talking about when you're thinking about something really intensely and you're not really looking at anything in particular, you're just staring and thinking and not really seeing what is happening in front of your eyes.
I've found myself doing that only to "wake up" and realise I've been staring at someone or something without meaning to, simply because I'm been concentrating so hard on whatever I was thinking about. | Your brain cells require a lot of energy to work at full capacity, and your visual processing center is a fairly large portion of your brain (relative to the amount of space your eyes take up on your body). Put simply, your brain can choose which incoming sensory information is worth dedicating chemical energy to fully process. If you are deep in thought that requires significant frontal lobe usage (for some decision making) or if you're tired and don't have the energy for much of anything, your brain could turn its processing power away from your visual field. You'd still be processing the incoming light waves to an extent, but not much of it would reach your consciousness. | 1,958 | 2,098 |
CMV: It is offensive to call descendants of slaves African American and is better to call them black | My argument basically hinges around the fact that
A. calling black people African American subtly makes them seem less American (they are not).
B. White people are simply called white (people generally don't call them Caucasian in general conversation)
C. African American naming has an actual utility: for first-2nd generation immigrants that immigrated here from Africa
D. Not all people that are called 'African American' are actually from Africa (obviously we are all 'from' Africa, but that was far longer ago and out of the scope of this point).
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In essence, calling descendants of slave, "African American", is incorrect and subtly makes them seem less American. The vast majority of them are not culturally African, were not raised by culturally African people & their only tie to Africa is several (5 or more most likely) generations ago. I think calling them black is more inline what calling Caucasian people white and respects that they ARE American firstly and not Africans firstly.
The only exception to this would be people who wish to be called African American, but unless they say to call them that, I would think it would be less offensive to simply call them black. | "Black" is ambiguous, since the people who are considered "black" varies from culture to culture.
"African American" refers explicitly to black people in the United States. It refers them having at least some degree of African ancestry | 28 | 40 |
ELI5: Why has no one crossed a dandelion with a carrot or parsnip, thus creating a nutritious vegetable that grows wild as a weed? | A few things. First, dandelions *are* nutritious vegetables that you can eat lots of ways.
Second, a weed is just any unwanted plant - they typically grow more aggressively than cultivated plants because they are evolved specifically for the environment in which they are found and because they don't waste any energy producing something extra for humans. For example, there are wild carrots, they just don't produce as large and tasty a root as cultivated carrots. Cultivated carrots need more support, because we've bred them to be *inefficient* as plants in order to be efficient as food. It's hard to get the weedy-ness of a weed and the wasteful extravagance of cultivated plant.
(Also, it's typically only possible to cross plant varieties of the same species or at least the same genus. Otherwise you're crossing wildly different species - it's like trying to get a chicken and a pig to successfully mate. Maybe it would produce delicious bacon flavored wings, but too bad cuz it ain't gonna happen.)
You might be interested in heirloom plants varieties, though - these are older varieties of cultivated crops that typically offer a lot more variety than more modern versions and tend to be more adapted to specific areas. | 182 | 246 |
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ELI5: Why is it that when you cut a small part of plastic it makes tearing much easier? | Making a cut produces a focus point that will have to absorb all of your applied stress, rather than spreading it more evenly across the entire surface.
The plastic is strong enough in bulk to absorb your strength, but not strong enough to stop all that force applied to a single spot. | 25 | 17 |
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From what I understand, we have only discovered a tiny fraction of the species on earth. Is life so diverse that I may have species that are unique to a 10 acre plot of land? | Maybe just wishful thinking on my part, it would be pretty neat if there were species that evolved into something new while on our land. Any type of life... animals, bugs, plants or microorganisms although I have a feeling that last one is an entire world of its own. We live in a rural area in the southern U.S. with a natural creek and I see so many different bugs when I go exploring. The creek only goes about a half mile and I've seen fish in it, I don't even know how they got there.
Please don't laugh at me if it's completely impossible. Help me understand just how "local" our local wildlife is and how likely it is that we have noticeable evolution going on in our own backyard.
Edit: We've been here since the 1970's and there are constant changes in the types of animals or plants that thrive and dominate here. We never do anything intentionally to influence that. | You have to consider how we discover species. So for example we've almost certainly encountered 90% of the mammals on our planet, but we might be at around 20% of insects and 5% of bacteria. Similarly, we might know about 70% of river-dwelling aquatic organisms and 20% for those in our oceans.
So if you go take a look in a creek in your backyard, chances are slim you'll find a new species, simply because those sorts of environments are well-studied and you're unlikely to have the tools to do better. On the other hand, if you go out there and take water samples and put the microorganisms through a whole-genome sequencer, you're almost certain to find something new. | 12 | 37 |
CMV: nepotism is fine outside of government and publicly traded corporations | the reason why nepotism is bad inside government and publicly traded corporations is that the person who gets the job is rarely, if ever, the best person for the job. when a person is appointed to a position of authority and control because they are family or close friends, there is damage done to the owners. in the case of the nation, the person is doing damage to the taxpayers. in the case of publicly traded corporations, the damage is done to the stockholders.
that is not the case in a privately owned business or in trades. preferring family and close friends is good for you, your family, and your culture. it is good for your family because it provides your offspring with what they need to be successful. it is good for your culture because it gives everyone in the community an additional reason to be close and to share. | >good for you
To the extent that you care about the success of your business, it may not be good for you since, as you point out, you may not be hiring the person most qualified for the job. Managing a family member also comes with its own set of potential difficulties which may cause you more stress.
>good for your family
Combining work and family can often cause rifts and broken relationships. Certainly it works for some, but it is devastating for others. Having a falling out with an employee or business partner is a whole lot more complicated when they are also your family.
>good for your culture
Nepotism encourages complacence, because people have a opportunities without actually having to have earned it. | 35 | 20 |
ELI5: what's up with the specific jargon and dialect of airline employees? | Flight attendants have the most unusual cadence, and they all seem to talk the same way.
"Ladies AND gentlemen, welcome TO Atlanta where the local time IS 4:45pm."
They always seem to stress and emphasize the least important words in a sentence. Is this taught to them for some reason in training? Does it somehow come across more clearly over a microphone?
Also, they always say, "we have started our descent inTO the Atlanta AREA." Why do they call it the Atlanta "area" rather than just Atlanta? I hope we aren't going to land in the general "area" of the Atlanta airport; I hope we are going to land at the actual airport. | Most of the odd emphasis is a speaking technique that gives the pilots time to think about what they are saying. Pilots have multiple flights a day and multiple locations, so keeping track of all that information in their head is hard. Instead they are looking over their flight itinerary and finding the relevant information to the passengers.
"Ladies and gentlemen, welcome TO...(scanning for landing location) Atlanta where the local time IS... (scanning for time) 4:45pm."
They take the time because could you image how quickly anger and panic would start from the passengers if the pilot said they were about to land in the wrong city, or later than expected and people were going to miss their connecting flights? The half a second pause prevents this.
> Also, they always say, "we have started our descent inTO the Atlanta AREA." Why do they call it the Atlanta "area"
A simple answer to this, many large airports are not actually in the city that they service. As an example the Cincinnati airport is actually not even located in Ohio, it is across the river in Kentucky. The pilot saying that you are landing in Cincinnati would be inaccurate, but saying that you are landing in Hebron Kentucky would be distressing to people that thought they were flying to Cincinnati.
Hope that helps.
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What are the differences between Quantum Mechanics and Classical Mechanics, and how and why do they manifest? | The equation
x̂(t) = x̂(0) + p̂(0) t/m
is arrived at after applying the commutator value \[x̂, p̂\] = iħ to the Heisenberg Equation of Motion for position of a free mass which says
dx̂/dt = i\[Ĥ,x̂\].
In classical mechanics, x and p can be determined simultaneously with infinite precision, that is to say, the Uncertainty relation, the Quantum Commutator is at the heart of which, does not exist in CM, and yet the classical analogue of the Quantum Commutator, the Poisson Bracket {x,p} = 1, leads to the same equation as above for the classical position of a free mass after using a classical Hamiltonian.
So why do these apparent similarities lead to different (*for ex., the abovementioned uncertainty principles, which I know arises due to Cauchy-Schwarz inequality restrictions on the Hilbert vector space, but what prevents this in CM vector spaces?*) as well as similar (equation of motion) results? What actually makes CM different than QM?
And what are some more such examples where CM and QM differ in results? | >What actually makes CM different than QM?
The canonical Poisson bracket and canonical commutation relation look similar on the surface, but the interpretations of those equations are very different. Just look at the postulates of QM versus the postulates of classical mechanics (Shankar has a good comparison in his QM text). x and p mean very different things in QM and CM. In classical mechanics, they are continuous, real-valued functions, parametrized by time. And to find them, you just solve Hamilton's equations. In QM, these are Hermitian operators. Particles don't have well-defined positions or momenta, they have state vectors (or wavefunctions, in the coordinate representation).
As for how they differ in results, see any of the major experiments in quantum mechanics (double slit, Stern-Gerlach, etc.). Classical mechanics would not correctly predict the results. | 68 | 228 |
ELI5: how do LED grow lights replicate the sun when growing plants . how does photosynthesis and respiration happen? | Photosynthesis is just a chemical reaction (or more accurately, a super complicated chain of chemical reactions) that get activated when certain chemicals absorb certain frequencies of light.
We can manufacture LEDs that send out those frequencies of light, so they trigger the reactions, allowing plants to photosynthesize. | 78 | 96 |
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Angler fish lure their prey using light emitting bacteria, but why would the prey which spends its entire life in total darkness of the ocean depths be even lured to such an obvious trap? Do only "lost" living organisms from the upper layers get tricked like that? | Bioluminesence is the most common form of communication in deep-sea animals. It's also often used as a defensive manouver - to distract, deter, and even mark others. A glow might signal prey trying to communicate, but also a commotion where prey is likely to be found. | 839 | 1,432 |
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ELI5: Why are there so many great Eastern European Boxers, strongmen, and and mixed martial artists? | Different cultures place different emphasis on different sports. In Eastern Europe, the strongman/strongwoman sports are much more revered than they are in other places. As such, more people take those sports up as their childhood sport of choice, which means that there is a larger talent pool for elite athletes to emerge from.
It's also worth noting that the startup costs for getting into these sports is very low. All you need is some padding, some gloves, and someone with a bit of training to show you the ropes, and you can *get started* at boxing. Compare that to, say, equestrian sports, which require a horse, full time lodging and care for the horse, and a host of other costs. A lot of Eastern Europe is poor compared to Western Europe and North America, so again, that funnels people into these sports. | 12 | 16 |
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Going to College and im looking at majoring in Computer science and i have a few questions. | 1. What is the difference between computer science and software engineering i looked around google and couldnt find a consistent answer.
2. Is getting a masters worth it?
3. Where are some of the best places to work in the field of computer science (such as pay to cost of living or other aspects that relate to daily life).
Thanks for any help in advance! sorry if these questions are dumb lol. Also sorry if this isnt the right page to post this i didnt know where else to post it | 1/ Generally, Computer Science will be more theoretical while Software Engineering more applied. Consider as an analogy majoring in Physics vs' Mechanical Engineering.
2/ A masters can be worthwhile. Startups and Silicon Valley generally won't care too much, but bigger companies and government jobs might. It also may be good if you really want to hone your skills in one area (e.g. cybersecurity or machine learning).
3/ Well, right now you can work from anywhere :) #COVID
I've only lived in SFBay and NYC since graduation, so I'll defer to people with experience elsewhere. | 18 | 26 |
Is it better to be a jack of all trades but a master to none in CS? | I've always been curious because whenever anybody looks up how long it takes to learn a certain language, skill, or whatever, the answers from professionals is always "A couple hours to a few months to learn the basics, but a lifetime to master". But it also seems that many people bounce around for a while in their CS career to different companies/jobs working their way up with different skills. So what do you think? | One good option between those two extremes is to be a T-shaped engineer. Have broad, shallow knowledge across a variety of topics, and then deep knowledge in one topic in particular.
The deep knowledge makes you a valuable topic expert. I’d also argue that learning something deeply exercises different cognitive skills than shallow learning. Once you have these skills, it’s easier to go deeper in another topic should your role change. Also, don’t forget that being an expert in something is great for marketing yourself.
Broad knowledge has huge benefits when collaborating with other topic experts, because you already have some idea of what they’re doing and how to communicate with them. On the flipside, it also allows you to be more self-sufficient for the easier stuff outside of your expertise.
It’s becoming more common for companies to try to build cross-functional teams of T-shaped engineers. | 26 | 35 |
Is it feasible to understand the entirety of Firefox's source code? | Hi, I'm a programming noob, and I was wondering about this: Programming is very specific nowadays, and a modern web browser such as Firefox (or Chromium, for that matter) has thousands of developers working on it. Moreover, the people who work on the UI are different from the people who work on the JS interpreter and debugger, which are different from the people who work on the rendering engine, and so on.
As a hypothetical question, would it be possible to understand every nook and cranny of a massive software such as a modern web browser? I mean understand well enough to be able to read the source code of any given part and maintain/fix bugs anywhere. Bonus: Is there any "Renaissance" programmer who actually does that? | It's possible to have the underlying knowledge and comprehension that would make it (relatively) easy to familiarize yourself with a given piece of code quickly, but honestly, even for projects with a single developer, they can rarely keep track of all the moving parts at once. It's extremely common for developers to return to a portion of their own code base and realize they have forgotten all of the details, and have to refamiliarize themselves with it. | 30 | 21 |
CMV: Immigration is more beneficial to the US than it is harmful | EDIT: I’m not gonna lie. This was research for my school project
The US is a large country and can support plenty of people. The American dream is a haven for those who need to run from persecution, especially those in Central America coming here to escape their countries’ peril. scientific and intellectual progress could be heightened with more people. Terrorism is an threat, but the chance is minuscule compared to the benefits of having more minds and more workers in America.
Even if it is not the responsibility for America to help out other failing countries, it would certainly be in our best interest to do so.
Integrating these people into our society would allow America to gain more laborers, and opportunities to gain new researchers and educated citizens. This could help our economy and possibly make our military grow stronger. These immigrants could further America’s progress and also large scale immigration could perhaps cause a military alliance to be created.
Edit: This is in reference to legal immigration | Immigration of all sorts (legal/illegal) always has 2 negative effects - rising prices because of the increased demand for goods (especially housing/rents), and lower wages because of the increased supply of labor. Who benefits from increased rents and reduced wages? The elites who are landlords and owners of companies that employ lots of cheap labor. Who loses? People who work for a living and spend a significant amount of their income on housing (pretty much everyone else).
Now, if the immigrants can provide value to a country by filling jobs that the existing population did not have the skills to do OR by bringing capital into the country to invest, that can overcome those effects and a create a net positive. In addition, the net present value of all of the costs associated with immigrants and their children (schooling, welfare, government healthcare, etc.) exceeds the NPV of the taxes they will pay in their lifetimes, it will be a net negative for everyone else because they will cost other citizens money via taxes.
This is why mass immigration of the late 19th and early 20th century was so successful. There was almost no government spending on entitlements, so there was no public cost for even poor immigrants. The economy was also largely resource based- that is agriculture, natural resource extraction, and manufacturing. The more labor we had, the more economic output we could make. Now we have government sponsored everything for poor people and our economy is almost entirely service based, which means that adding lots of low skilled people doesn't generate economic growth.
The problem with unrestricted immigration is that the people who arrive often do not have skills to fill in demand jobs that help grow the economy, and in general are very low skilled. They almost never bring significant capital with them. This means they will pay very little tax while consuming a lot of tax money, which is not a benefit to the citizens who are paying the tax.
So ultimately, it depends on your perspective. If you are a rich owner of a bunch of apartment buildings and factories, then immigration is pretty much always great. If you are a lower middle class renter with a manual job, then it is not so great. | 39 | 71 |
Why do we still teach Bohr's model in school? | If we know that Niels Bohr's atomic theory (orbitals) is incorrect, why do we still teach it in schools? | Good question, I'd guess because its easy to understand and is functional unless you go into chemistry or physics. It would be pretty hard to explain probability density, wave functions, Heisenberg principles and quanta to high schoolers though. | 39 | 22 |
[Harry Potter] Is there seriously a spell designed solely and exclusively to transform animals into water goblets? (Vera Verto) What would the possible practical use of such a spell? Why teach it to kids? | Ok, I get it, kids need to practice, but are y'all claiming that the sole purpose of this spell is to teach kids the basics of transfiguration? Spells do not come from nothing, someone invented them, usually for a purpose. What is the practical application of turning animals into water goblets? If you're threatened by a lion it may be easier to, you know, just kill it. And if you desperately need a water goblet, then I'm pretty sure it'd be easier to get one from transforming something that is not ALIVE. Or maybe not, correct me if I'm wrong. | As practice. Doing magic well requires some familiarity with moving magic around. Consider them like agility drills for football players. There is little practical application in and of itself for running in place and dropping down to the ground. But do it enough and you start to bulid a little agility.
Similarly, turn animals into water goblets enough, and you will start to get a basic level of skill and understanding of the art of transfiguration. | 213 | 308 |
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