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ELI5: Why do cysts keep coming back over and over if the sac isn't removed? Does the sac generate more sebacum (sp?) or is it something else?

To answer your question, it is important to define the terms which describe what laypeople call "cysts." There are abscesses which are pus-filled pockets within the skin and associated soft tissue. They form when bacteria get into the tissue and multiply. Pus is a thick, typically off-white fluid which is made of dead bacteria, body fluids, and dead white blood cells that are trying to fight the infection. A sebaceous cyst (sometimes called an epidermoid cyst) is a sterile (not infected) pocket of material under the skin. It is like an abscess but not filled with pus. There are several different types but the difference is not important for this explanation. They form most commonly when skin cells start growing underneath the layer they are supposed to. They form a round structure that fills up with dead skin cells. Usually when skin cells die, they flake off the body but since these skin cells are trapped under the skin, the dead cells fill up the cyst. The material inside a sebaceous cyst is called sebum and it is much thicker than pus; sebum is like toothpaste while pus is like gravy. You treat abscesses and sebaceous cysts differentially. An abscess must be cut into so pus can drain. This takes pressure off the surrounding tissue, improves blood flow, and allows white blood cells, healing cells, and antibiotics into the area. An abscess will not heal until it drains because the bacteria can hide inside the pocket from white blood cells and antibiotics. On the other hand, if you try to remove the sebum from a sebaceous cyst (I say remove because it is so thick that it will not drain on its own even if you cut the cyst open), it will decrease the size of the cyst temporarily but it can recur. This is because the skin cells that formed the sebum in the first place are still there. They are the "sac" that you referred to in your question. As an aside, sometimes sebaceous cysts can become inflamed if bacteria gets inside the sebum. In those cases, doctors typically prescribe antibiotics and allow the infection to resolve before attempting to cut the sac out. It is difficult to remove an inflamed sebaceous cyst because the sac becomes very fragile and will tear into multiple little pieces rather than come out in one or a few large pieces. If you leave just a single tiny portion behind, then the entire cyst can return. For bonus material, people can develop recurrent abscesses in the same place as well. This is not due to failure to fully remove a "sac" (there is none in an abscess), but rather due to scar tissue that forms in the skin and underlying tissue. If that area becomes infected again, an abscess has an easier time forming in the same location because of that scar tissue, like grooves that form in the couch cushion encourage you to sit in that spot again.

ELI5: why do atoms decay?

Say I have 2 atoms of gold, i cannot tell one apart from another, yet one is going to decay while another one will continue to be, so what makes 2 seemingly identical atoms behave differently? what is that something that makes them different? Is there some sort of fatigue at atom level?

It's hard to ELI5 for quantum physics. Atoms and the bits that make them up (protons, neutrons, electrons) and the bits that protons and neutrons are made of (quarks) all have behaviour that is different to what we consider 'normal' stuff. It is natural for them to randomly change, with a chance of this change happening in a given time. It's just what they do, because they are all trying to get to what is known as their lowest energy state. Other things get in the way, like gravity, other Atoms and bits of radiation hitting them. But over time, everything at a quantum level is trying to change in order to reach lowest energy. So one atom might change now, one might change later, but eventually, everything in the universe will reach the low energy state.

Questions to ask when I visit a potential grad school

I'm visiting my first grad school in a couple weeks. At this point it looks like it's probably my top choice. What should I make sure to find out before I make a final decision?

Its important to remember that if you've already been accepted, that the department is trying to impress YOU to join their department. Grad students are cheap teaching labor, and they do research that brings in grant money. If you've already been accepted, it means that they want you. Ask other grad students what they like and dislike about the department. Ask them what every day life is like, the culture in the department, what kind of prelims exams they make you take, how many classes you have to take, how many semesters you are required to teach, what the yearly stipend is, what the average graduation time is for PhD students, how many people leave with their masters, how much rent is for an apartment around town.

How come there is no cancer of the muscle or the heart?

I have never heard of biceps cancer or trapezius cancer. Doesn't cancer affect muscle cells?

In general, cancers are most likely to occur in tissues with cell populations that divide a lot over the lifespan of the organism. These include epithelial layers (skin, GI tract, breast, prostate) , blood cells, etc. Muscle and nerve divide much less frequently so cancers arising from these cell populations are very rare. You may be thinking, "then what about brain cancer?" Most brain cancers arise not from neurons themselves but from the supportive glial cells which divide more often.

ELI5: how do ocean animals navigate in their 360° environment?

I know dolphins and whales have sonar. But how about fish, jellyfish, giant squid, sea turtles etc? They have no visual points of reference like us land animals, they can literally travel in any direction (vs. our fairly linear plane of movement; although I’m assuming at least that they can sense gravity and therefore know up from down), and yet can navigate so confidently that, for example, animals like sea turtles can return without fail to the same location year after year to lay eggs.

Most of them still use vision and touch (feeling currents.... like how you can feel a draft of air when someone goes by) for navigation in the near field. For farther navigation, a lot of sea animals either have natal recognition (e.g. salmon which “remember” how to get to the streamheads where they were born, and use olfactory (smell) or magnetic cues to help) or use electromagnetic fields similar to how birds migrate. There’s a lot of different sensory organs that are used in different ways by different animals, but it’s all the same concept, really. Fish swimming in schools use lateral lines which are sensitive to the tiny electric impulses sent out by animal movement to avoid collision and navigate in the school. Rambled a little... hope that answers your question?

how does fat and protein digestion works? difference between lean and fatty protein and the effect on digestion time?

Hello altogether, unfortunately I have many different questions about all things fat and protein digestion, specifically regarding animal products with different fat content. I want to understand the science and the chemistry behind the whole topic and also educate myself even further because it seems like I know nothing. I tried to do some „research“ and found several different claims, opinions and explanations. Before I get into the questions, I want to present the claims from the two different „camps“ because obviously there are more schools of thought?! **Team fatty meat/protein:** *The more fat that is in the protein the more delayed is digestion and therefore it sits in the small intestine longer and the required enzymes have more time to do their work and help digest the protein and the fat more efficiently, fully and easier! If the protein is leaner it goes to the digestive tract much faster, probably undigested and not fully absorbed by the small intestine.* *Muscle meats like chicken breast or lean steak can aggravate constipation and therefore its beneficial to replace them with gelatinous meats instead and cuts with more soft tissue like chicken thighs, fatty meats etc. Humans can only use meat fibers properly when they come with fat, collagen and other substances.* *Dark meat like chicken thighs or fatty cuts of meat contain more nutrients like zinc, iron and more vitamins like b12 additional folate, pantothenic acid, selenium, phosphorous, and vitamins K and A which aids in digestion.* **Team lean meat/protein:** *Meats with higher fat content take longer to digest. Also, foods with the least amount of fat, least amount connective tissues, and shorter muscle fibers are easier to digest. It means that fish is the easiest meat to digest, then poultry, pork and lastly beef* *it also means that if the piece of chicken or turkey you are eating has more fat or long muscle fibers (thighs or drumsticks) than a LEAN piece of steak or a LEAN cut of pork, then that piece of chicken will be harder to digest!* *A piece of boneless skinless chicken breast is easier to digest than a chicken thigh. Lean ground beef (93/7) is easier to digest than fattier ground beef (80/20) and a lean filet is easier to digest than a ribeye or beef brisket, chick etc.* Ok, so far so good and I’m confused. What I found is a study about myoglobin and it seems like that dark meat or cuts of poultry and beef with more myoglobin and more connective tissue are „harder“ to digest than white meat or poultry/beef with less myoglobin!? **My questions are:** What sits longer in the stomach, how long and why? What sits longer in the small intestine, how long and why? What kind of poultry/meat moves faster through the digestive tract, especially through the small intestine? Which cuts require more effort, more enzymes, more stomach acid? Which cuts are more taxing on the liver? Is it easier and quicker for the small intestine to absorb nutrients from lean or fatty protein and why? which factor determines whether a piece of animal protein/fat is light or heavy, fast or slow digesting when looking at the fat/food in isolation. Is it the fat content, connective tissue, a combination? Is a fatty ribeye or hamburger patty (70/30 or 80/20) easier to digest than a lean filet steak? Or a fatty chicken thigh easier than a chicken breast? Pretend that all meats/beef/poultry are cooked to a moist internal temperature, not overcooked, tough or dry Are low fat dairy products easier and quicker to digest than full fat dairy products? At the end of the day I want to know which cuts of poultry/meat/beef/fish are easier to digest for the stomach and small intestine and which cuts are moving faster through the digestive tract. Also from which cuts the small intestine can easier absorb nutrients? Im looking for a evidence based scientific answers in plain English that I can understand what’s going on and why. I don’t need study’s, although it would be nice, but everything backed up with science based explanations and evidence not opinions or preferences like almost everything on YouTube, food blogs etc. I’m looking for people who study this stuff or work in this field and know what they talking about. Im very thankful for every explanation, help and for everyone who reads this. I appreciate every Tipp where and how I can educate myself because I don’t want to be lazy. Thank you very much and have a great day

GI physiologist here: absorption of food stuffs depends entirely on chemical composition of the food. The food must move from the lumen of the gi tract across the walls of the cells lining the the small intestine and thence into the bloodstream. The cell walls are composed of lipid (fat), thus only fats can cross the cell wall unassisted. The fats that you eat are too big - both physically too big (must be crushed into smaller pieces) and chemically too big (must be broken down into it's component parts by the action of enzymes coming from the pancreas and/or stomach wall) to cross the cell wall in the form in which they are eaten. The breakdown from big hunks to small hunks occurs in the stomach due to repeated gastric contractions squashing the food and mixing it with the various gi secretions of saliva, acid and some enzymes. If the fat is not broken down sufficiently it can't be attacked by the enzymes because they are water soluble and can not fight their way through a big hunk of fat. This process requires time not required for non-fat foods so fats stay in the stomach longer than non-fats if eaten separately. It eaten together, everything is slowed down in the stomach. Once the fats are sufficiently broken down physically they pass into the small intestine where more enzymes finish the chemical breakdown into components small enough to pass through the lipid cell walls. Unfortunately, at this point the fatty particles are floating in the aqueous secretions of the stomach and small intestine and can not reach the lipid cell wall. To make matters worse there is also a layer of water bound to the lining of the small intestine which also blocks movement of the fat components. This is where bile comes into the picture. Molecules of bile are water soluble on one end and fat soluble on the other so they form into little tiny hollow balls with the fatty ends pointing into the center of the ball. As they form, the fatty food components are trapped inside the ball. The water soluble ends are pointing out from the ball so the entire ball is now water soluble. These balls (micelles) move through all the water and water layers and dump the fatty components directly on the cell walls where they can now pass through the wall into the cell. To pass from inside the cell out the back side into the blood the fatty components must form another hollow ball with the fatty material inside and proteins outside which allows the fatty material to move around in the blood once it is absorbed. Last but not least the fatty material moves from the small intestinal cells into the lymph not directly into the bloodstream where it must end up to be used for fuel. Thus it travels through the lymph system until it reaches the thoracic duct where it is dumped into the bloodstream. Obviously, fat digestion is a complex time- consuming process with many steps all of which must happen in the correct order. Malabsorption of fat is quite common and causes smelly diarrhea. Proteins are water soluble and special carriers exist in the walls of cells allowing amino acids to be transported into and out of the cells so the process of protein digestion and absorption is simple and rapid. Eat the protein, proteases secreted by the mouth, stomach and pancreas begin to break down the proteins into constituent amino acids. These move directly into the small intestine where they bind to the carriers on the cell walls and viola, absorption. Malabsorption of proteins is rare and usually involves a congenitally missing carrier. Complete digestion and absorption of a high fat meal may take several hours longer than that of low fat meal.

If the Sun were to suddenly disappear how long would it take for the Earth to freeze?

Title pretty much. Question came to me when watching a Doctor Who episode. Edit: From a few comments, I think I need to be more specific. My freeze, I mean be unsuitable for human life without technology. I don't mean it as in walk out of a heated house and die. How long would it take for earth to be inhabitable by humans without any forms of technology. Thanks!

Your question should be clarified as: If the LIGHT from the sun were to stop reaching earth (for some unexplainable reason). If the sun actually vanished, the planets would abandon their orbit and well...it will not be a fun time.

Why is it that when you're in a "dark" room and you focus on a really dark spot, everything, even light, will start to fade away?

I know I probably didn't make any sense since it's hard to explain but imagine being in a dark room with nothing but a little red LED light in the center of the room, if you focus on a dark corner you can see how this light will fade away into darkness. Why is that?

What you describe is an example of Sensory Adaptation. Through the process of sensory adaptation, our sensory systems become less sensitive to constant, unchanging stimuli. In your scenario, if your eyes remain motionless, what little light is present will continually stimulate the same retinal photoreceptors at the same level. Sensory adaptation reduces our awareness of such a constant stimulus. In the case, the dim light will seem to fade. But twitch your eyes just a bit and the perception is restored. Your other senses exhibit similar adaptations. You may smell a pungent aroma upon entering a room, but remain there and soon you may be entirely unaware of it. When you wear a new wristwatch or ring, you may at first be aware of the sensation of pressure on your skin, but after a while you no longer notice it.

How do we know chemical reactions doesn't react with air?

for example A+B-> C How do we know there isn't air involved in A+B? Don't you need to have a vacuüm to be 100% sure there is no air involved?

We can pretty easily see that oxygen isn't in the products if we can see what atoms make up both the reactants and products, and so for that we can rule out air involvement. If we are a little unsure we can do isotopic studies to actively watch the movement of atoms to confirm. However, your question gets to the point that all chemical reactions happen in some kind of medium, and in chemistry we call that the solvent. It can be air, water, acetone, oil, inside a metal, etc, but by definition there is some area within which the reaction is taking place. It turns out this can play a huge role in how chemical reactions progress. In the simplest case the solvent can interfere with the reaction and become a reactant. If you try to do reduce something in a liquid there can be significant effects of oxygen dissolved in that liquid reoxidizing your stuff. However, as discussed above we can generally track these side reactions and predict them well. The other effect is that solvents will change the way that your reactants come together. For example, when A and B come together you must go through some A---B transition state before you get your final C. If whatever medium your reaction is in is good at stabilizing that A---B transition state then you might be able to make the reaction more efficient, faster, or require less activation energy. A lot of organic chemists spend a long time trying out their reactions in different solvents just to find the one that allows their reaction to work.

Can multiple exact same sounds played over each other produce a louder decibel output than the original sound?

This is an example of constructive or destructive interference. If the waves are in-phase, this is constructive interference. The intensities of the two waves will add up and create one much more intense wave. If the two waves are out of phase, then destructive interference will be experienced. If we have destructive interference, the waves will create a lower intensity wave, but as mentioned before, it depends on where the sound is measured because it will be louder in some places, and much quieter in others.

ELI5: How come a large portion of African Americans are such devout Christians?

The religion gave them faith in a better future during slavery, and it has been passed on culturally from mother to son, father to daughter. They weren't allowed to practice any of their native faiths, and since slaves came from many diverse tribes none of them would have had the same religions, so Christianity took on very well with slaves. It's a religion that's all about being oppressed after all.

How does mercury polish silver?

ive seen it , but i want to know!

Two processes: Mercury dissolves the outer layer of silver in amalgamation, as another poster stated. Also, mercury directly reacts with silver sulfide (the main component of tarnish) to form cinnabar (HgS) and metallic silver, so it directly attacks the tarnish as well.

[Economics] What would happen if Amazon replaced... everything?

I find myself doing an increasing amount of my purchases through online vendors, primarily amazon.com. The recent announcement that [office depot will be closing 400 locations](http://www.usatoday.com/story/money/business/2014/05/06/office-depot-plans-to-close-stores/8756183/) got me thinking: what would be the consequences if the bulk of brick-and-mortar retailers were completely overtaken and retail sales of basically everything were centralized through amazon.com? Would amazon essentially retain a monopoly on all goods, or would there be some mechanism through which to ensure competition? Would amazon need to be divided somehow? This is obviously hypothetical, but just imagine the worst case scenario. You want to buy something? Anything? You're going online and ordering it through the same website you would order anything else. How would that affect the economy and the marketplace? Besides convenience, would there be any positive outcomes or only negative results from this scenario?

When a distributor becomes powerful, one upside is that you then have a participant with enough market power to change standards in the industry. A famous example is Walmart and RFID. Walmart wanted RFID chips on all shipments to streamline their inventory processes. Because of their market power they were able to essentially mandate that to their suppliers. As a result RFID saw a swift global adoption. In a fragmented distribution channel RFID would have had to grow organically. If Amazon becomes more dominant, we'll start seeing more things that streamline their operations. For example they are already encouraging manufacturers to use less packaging for items, since items are always reboxed by them for shipping. Eventually "encouragement" becomes a mandate and a new global standard in how products are packaged.

ELI5:How did society withstand the sun prior to sunscreen?

I'm thinking of all societies prior to the invention of sunscreen as well as those lost at sea on a lifeboat. How?

For thousands of years, people in sunny regions had dark skin, while people in non-sunny regions sometimes had light skin, due to evolution. Only in recent centuries, with modern transportation, have millions of people been moving huge distances. So the problem of "I have the wrong skin color for this climate" is fairly new.

2 PhD students, same experiment

Hi, I started my PhD in Biology a week ago and I just found out that there is another PhD student (who started in October) working under my supervisor who is already working on the EXACT same experiment as me. What should I do?

Since you both started recently, this might perhaps be a "training wheels" experiment, and the supervisor might have given you both the same thing to do independently of each other, to double-check the results. If two inexperienced PhD students obtain the same data, that's probably good data. There's no harm in asking nicely your supervisor about this, though, if you feel uncomfortable being in the blind.

ELI5: How Do Boat Anchors Work?

How does a boat's anchor hold it in place despite being so much lighter than the boat itself? Surely the anchor doesn't always catch on something on the sea/lake bottom, otherwise it would be hard to retrieve right? Esp as it relates to large vessels like cruise ships the anchors seem so small in comparison. Is there some ratio of anchor-to-boat size that makes it all work?

I know that this answer applied to large ships (merchant ships, cruise liners, Naval vessels). The anchor does not hold the ship in it's position while anchored. Instead, the anchor serves as a weighted end to assist in paying out the chain. The anchor drops to the ocean floor and the momentum (assisted with the ship moving slightly astern) carries out additional chain. The collective weight of this chain and anchor is what holds the vessel in place. Source: US Sailor

Can someone explain me the chemistry behind stains and why some stains cannot be removed?

**TL;DR - Some stains are held in place by weak chemical bonds but others are held by strong covalent chemical bonds that won't be broken by traditional solvents or surfactants (soaps).** In principle a stain is a bond between the surface of the original material and the molecules of the stain agent. That bond strength can vary greatly depending on the original surface and the stain agent. Some surfaces have very little microscopic surface area (e.g. a laminate countertop) whereas others like a cotton thread (hundreds of individual fibers) have a lot of area. Some materials are also porous (e.g. wood) and that adds extra surface area. The stain agent reacts with the available surface area in some way. An example of a weak interaction might be a solvent that dries up and leaves a film of stain on surface, like most colored liquids dried on metal. If you add solvent the stain will move from the surface back into the liquid. If the surface is porous or has a lot of area, then it might take a lot of time for the stain to all dissolve, because the solvent has to get into the pore and the stain has to then get out of the pore. Some stain materials will form stronger bonds with the original surface and won't just dissolve into their original solvent. In those cases people add a surfactant (e.g. soap) or cosolvent to help increase the solubility of the stain in the cleaning solution vs the adsorption of the stain to the surface. Sometimes the reaction is so strong that most normal solvents won't break the bond between the stain and the surface. This is the case with most dyes which are engineered to covalently bond to fabrics and not dissolve into a solvent poured onto the fabric. If the bond is strong enough it may not be possible to break the surface-dye bond without also damaging the material that makes the surface. An example of this would be bleach which is good at destroying dye molecules, but also eats away at the underlying material - although at a much slower rate.

ELI5: How do lasers cut through objects?

Light is a form of energy, like thermal energy etc. Laser light can be a very concentrated (focused) form of energy. Energy is conserved (it cannot be created or destroyed) so when high energy laser hits an object, that energy must be transformed to another form of energy, usually thermal. This raises the temperature of the object and, if the laser is strong and focused enough, it will melt or boil or burn at the point of contact. Move the laser and it will resemble a cut.

Why was nuclear power originally researched?

What was the original purpose for studying nuclear energy or nuclear fission? Was it to help man-kind originally, or was researched to create a new weapon? I am just trying to understand the historical purpose of nuclear energy and what the scientists had in mind when originally researching it.

The first experiments were pure scientific research into the nature of the atom and its nucleus. But after that, the applications for power and bombs were thought up pretty much simultaneously. The same team of French scientists, on the same day in 1939, filed patents for nuclear reactors and for nuclear bombs. The first working reactor, Chicago Pile-1, was built in 1942 as part of the Manhattan project. The investment of money and effort was heavily towards building an atomic bomb, because of the historical coincidence that the relevant science was discovered just before the Second World War.

Pilot wave theory, a theory involving highly complex and non-linear differential equations, is fully equivalent to matrix mechanics, a theory involving only linear differential equations. Does this have implications for our ability to solve non-linear differential equations?

Matrix mechanics is contained in pilot wave theory. Pilot wave theory just adds an equation describing trajectories which is non-linear. It has no implications at all on our ability to solve non-linear equations.

Is there a difference in the quality of happiness experienced from 'engineered' activities like video games compared to the happiness experienced from 'natural' activities like rock climbing?

I've been thinking about the types of activities people fill their lives with in modern times compared to what people did in the past and wondered if there is any way to differentiate the levels of happiness or satisfaction obtained from those activities. Things like video games and content streaming sites have been designed to make people feel happy, and as a result people keep coming back to these activities, but it seems that, personally, these things do not give the same 'quality' of happiness or satisfaction as something like riding my motorcycle in the mountains. Why is that?

In terms of reward experienced during these activities, no. Studies have shown that the neural reward experienced from gaming can be similar to or greater than that of other highly enjoyable activities, such as sex or even drugs. Happiness, however, is very multifaceted, and you could argue that certain engineered hobbies like gaming may produce less happiness because of their negative consequences such as obesity, loneliness, etc.

ELI5: why do most pictures of deformed babies happen to be from Southern Asia? Is there something specific to that region that causes it versus other 3rd world areas?

A large amount of people in sub-optimal conditions such as dirty water, little food, various diseases, etc is what many people believe. But it's undeniable that Korea, Vietnam and Laos are all heavily affected by Agent Orange, Pink and Purple. Thr Agents are herbicidal growth regulators used by American military forces in various campaigns to kill the foliage and prevent snipers from having cover to sit and wait in. The problem with the Agents, particularly Agent Orange, is that it contains dioxins which bind with hormone receptors. When that occurs in pregnant women whose fetuses are still developing, it can simply stop certain developments from happening. This causes things like low bone density, malformed bones, lack of eyes or limbs, underdeveloped brains. It's not just Southeast Asia that suffers from it many births in the USA have been affected by the chemicals because soldiers that were caught in the sprays have the poison in their bodies and passed it to their spouses via semen and caused defective births.

ELI5: How do psychology researchers obtain informed consent without tipping their subjects off on the subject of the study?

I know that subjects of research studies must give informed consent before they are allowed to participate. I also know that informing subjects of psychological experiments of the study's true purpose can influence the results. How are these two concerns reconciled?

You have to tell them what will happen to them during the study. You don't have to tell them why you are doing it or what conclusions you will draw, except in the vaguest of terms. "You will answer a series of timed questionnaires while being observed by our researchers, to increase our knowledge about how people make decisions". Maybe they don't care about your answers to the quizzes, only your facial expressions while you take them.

ELI5: Carcinogens; How Do They Work?

I understand that cancer is an uncontrolled growth/replication of benevolent cells, but how do carcinogens cause/increase the chances of getting cancer? As an addendum, what makes some people more susceptible to getting cancer. My great aunt smoked from the age of 12 to the day she died of advanced alzheimers at 92, and never had any kind of cancer. On the other hand, my friend never smokes anything, and doesn't hang around smokers, yet he developed lung cancer at 25. Why?

Carcinogen is a very broad term for agents which can damage your DNA, it encompasses all sorts of things from reactive substances to different types of radiation. When a carcinogen reaches a cell and manages to hit your DNA, one of several things happens. If you're lucky, the DNA is repaired fully, which is the case most of the time. If you're somewhat lucky, it's repaired in the wrong way but the change doesn't matter and the cell lives on as per usual. If you're somewhat less lucky, the change is severe and the cell can no longer sustain itself and dies - not that it matters when you have billions upon billions of identical ones. If you're _extremely_ unlucky the damage occurs in such a way that the cell "forgets" that it's supposed to stop replicating, resulting in the uncontrolled growth you mentioned. As for why your grandmother didn't get cancer, the answer is most likely "dumb luck". It is possible that there are some genetics involved too but the mechanics behind those are likely beyond our current understanding.

CMV: university shouldn’t be free

In the United States, there’s a push to make universities free in order to make education more available to the masses. While I do think education should be readily available to all interested parties, free university is going to take things down the wrong path. Going to university after high school has become the primary path for a large portion of young Americans. I think this used to be good as those who wanted to pursue higher education were previously barred by financial constraints. Through student loans and scholarships, those students were able to chase their dreams to help create a better society. Things I feel are different now: kids feel like it’s another stepping stone to securing a higher paying job that’ll keep them more safe from poverty than any other option. As more students go to university, I just feel as though the value of the diploma decreases, the wallets of the universities get fatter, and job market saturation makes for lower salaries thus making maintaining the quality of life experienced in college educated lives in decades previous more difficult. In addition, these kids are now competing in a global market where companies outsource to just as qualified candidates who get paid small hourly wages rather than a high paying salary. Don’t get it twisted: university in America is too expensive and the quality of education is top tier but it’s also not for everyone. Funding trade schools to increase manual labor jobs, funding STEM programs, or making the military seems like a more enticing options than making universities free.

The more educated your society is, the more chances of having people that make your country better. More education can be a reason for better civilians and less violent crimes. Even if free education where to be poor level compare to others, it still is something better than no education at all. Would you consider a system where there is free universities and private universities at the same time? Would it bother you than with more people with degrees, you will have to evaluate who to hire base on skills instead of what uni they graduated from?

Why are workers paid an hourly wage instead of a portion of the value they add to the product?

The question comes to me as a philosophy degree holding line cook. I watch the raw beef turn into a delicious hamburger, and yet I am compensated for my time rather than the work I put into the food. I can think of a few bumps in the road, but no real reason why not, besides the fact that businesses profit more by treating labor as a commodity. One of the minor problems would be figuring out how much work each employee did. But this would be simple enough considering our ticket system for tracking orders. You were at work from x to y and did z number of tickets totaling this much profit, and at your pay scale you get so much percentage of the profit.

I would say a major reason is the desire to keep labor at a relatively fixed cost. Under the current system, your employer knows exactly how long they'll be open and how much that will cost them in payroll. Giving you a percentage of the total product sold is much harder to predict. (Of course, keeping labor's share of the profits low is also a motivation.) Keep in kind this can benefit the employee as well. You are paid the same regardless of how many customers the restaurant has any given night. That makes it easier for you to establish a household budget.

ELI5: Why is mercury so dangerous?

Mercury replaces calcium, sodium, and iodine in body chemistry, disrupting the workings of these dependent bodily functions. For example, your thyroid will absorb mercury instead of iodine, it will disrupt your immune system functions. Your body uses calcium and sodium to transfer oxygen through cell membranes, mercury disrupts this transport system; it raises cell PH. Mercury causes inflammation.

How do things/people gain high status or become low status?

This is a huge question, could you maybe discuss it a little bit as to narrow it down? e.g. are you more interested in things or in people, do you have a particular society (place/time) in mind, maybe why you're asking the question

ELI5: What's the difference between intensive care medicine and emergency medicine?

Emergency care is about stabilising people so they can be treated for the problem whether that's a cast on a broken leg or emergency surgery following a car accident. They are about treating what is found and immediate life saving or harm reduction and moving people on either to further care or home one treatment competed Intensive care is very high dependency care usually 1to1 nursing for someone who is very seriously ill or in a condition that needs constant monitoring. So following complicated surgery or sepsis or ventilation required for example. People can be on itu/icu for long term treatment or just a few hours during surgery recovery. They are likely discharged to a normal ward or high dependancy ward for further recovery. (high dependancy may be 1to 3 nursing for those who need more care than a ward but not as much as icu)

[Game of Thrones] Shouldn't members of Unsullied army be significantly weaker than soldiers in other armies due to lower level of testosterone?

Yes and this is acknowledged in the books: "Others may be stronger or quicker or larger than the Unsullied. Some few may even equal their skill with sword and spear and shield. But nowhere between the seas will you ever find any more obedient." The point of the Unsullied is their unparalleled obedience and discipline combined with their peak level training. You're not buying them to win arm wrestling contests.

ELI5: According to data we have discovered 14% of all organisms on earth. Where does this number come from, if the other 86% of haven't been discovered yet (and therefore we don't know if they exist)?

Statistics like this are created based on looking at what is identified within a group. Perhaps an easier example. Let's say people are inspecting defects in a product. Someone in charge intentionally adds 10 defects. Then they watch and see what comes through the line, what is discovered by the process. If people only find 3 of the defects, then they can estimate they're catching 30% of the defects overall, letting 70% of the defects go through. On the other hand, if all 10 defects are discovered, then they know they're catching all or nearly all of the defects. The percentage of things they know about should roughly match the percentage of things they don't know about. It applies to other statistics as well, like crime stats. They can look at crimes they know happened but weren't reported through official channels, and look at crimes they know about and were reported. Looking at the difference shows about how many crimes go unreported. It is not exact, but if people are careful about how they create the stats they can be fairly accurate. For counting species there are several ways it can be done. One way is like above, to have one group track the number of species in an area and another group figure out how many are new. Another method is a linear regression, figuring out an approximately how many species there should be based on estimates and comparing it to how many have actually been identified. Also, most of the species that aren't discovered are small things. We're down to small numbers of new birds and mammals, often they are sub-species that get reclassified as a new species, or they're highly specialized species living in a remote and small geographic area. It is mostly bugs, fungi, and other small organism that are being discovered in large numbers. These are things that are hard to spot and identify, many only identified because of genetic testing on tiny or microscopic organisms.

ELI5: Why does cross breeding work between certain species but not all?

Your genetic code is like a recipe, a series of biological steps that describe how to make you you. Your unique recipe is created by going through your parents' recipes, and at each step choosing at random from your father or your mother. If both of your parents are German chocolate cakes, their recipes are going to be very similar and most the steps are are going to be the same. Maybe one uses a darker chocolate or has more pecans, but isn't going to matter too much which parent you get which step from. If one of your parents was a red velvet cake instead, the recipes are different, but still pretty close. There is pretty good chance you'll still get some sort of cake out of the combination, but it is going to be a pretty unusual one no one has ever seen before. But if one of your parents was a banana cream pie, those recipes are too different. When you try to combine them, you are probably just going to make a mess, and not get any sort of edible dessert out of your efforts.

ELI5:What makes us interested in something?

I mean, what happens in our body that makes us enjoy things we are interested in? And why is it that I can be interested in one thing but someone else wont be?

We develop interests through nature and nurture. You might have a inquisitive personality that makes you attracted to books or an analytical mind where strategy games pique your interest. If you had a dog growing up and it was your best friend you might like dogs and pets in general. If you had a dog growing up and it bit you once, you might hate dogs and have an irrational fear of them. If you're a younger sibling who got involved in a specific sport because your older brothers/sisters were competitive in it, you might have just been a part of it long enough that it became an interest. Humans are adaptable like that. Once you have learned the skills necessary to indulge in your interest, your brain will reward you for feeling successful the same way it does in other ways: dopamine! It's far too complex an answer to say exactly how an interest is developed.

The relationship between distance and torque seems like magic to me. What is actually happening to increase torque with a longer lever?

Why is the torque increased simply because you are farther away from your pivot point?

A more intuitive way to think about it is if you lengthen the arm you are actually creating a longer distance to travel to get the same amount of work done to rotate the same amount. Since you are moving a longer distance it is easier for you to move the arm. You do not have to put as much peak force on it.

CMV: If school children were treated like adults by teachers, overall behaviour and performance would improve.

I think it’s counter intuitive to give children freedom at school, because everyone’s first thought initially goes to taking the reigns off and facilitating chaos. But I think being respected as an equal is an important part of the learning process for a young person. It helps with encouraging them to discuss their views, improves their confidence in saying wrong answers and their confidence overall as the grow into adults. Even being given the freedom to go to the bathroom whenever they want, or not have to get a planner signed by a parent, in the long-run helps children respect and enjoy the school system more. Obviously some control and restrictions are necessary.

Sure, teachers respecting kids is a good idea. But to modify your perspective just a bit here: >CMV: If school children were treated like adults by teachers, overall behaviour and performance would improve. ... consider that teachers have *a lot* of things that they are responsible for that the children are not. Namely, the teacher is responsible for the learning of *all* the 2 dozen plus students in the class. As such, there are time constraints the teacher is having to work within, as well as processes that they need to follow in order to keep things moving, focused, and with less disruptions to achieve that goal more effectively. They are also typically having to impart a large volume of set curriculum to the students in that limited amount of time to prepare them for important exams that impact each students' progression. Meanwhile, the kids are only responsible for themselves, and only thinking primarily of what they themselves want, with less perspective on those "bigger picture" concerns (which they may not even be aware of). And things like having parents sign the planner is about having parents aware of / involved in their child's education - which is linked to better student outcomes. Students may not like having to get that signature - but it's not about that. It's about ensuring that parents are at least minimally aware of what's going on with their kid, which is beneficial for the kid. The school itself also often has *a lot* of rules and regulations that the teacher must follow as part of their job. Respect is all good. But also, consider that the role of the teacher and the goals they have to work toward involve way more than most students realize.

ELI5 Why does singing/rhyming help you memorize? Secondly, why does it seem to help motivate younger children to do things they normally wouldn't?

I could never get my 2yo daughter to help me clean up her toys, but once i started singing 'putting your toys in the box, putting your toys in the box' it's much easier to get her to go along.

The human brain is hard wired to see patterns and repetition, it's how we hunt, gather, communicate, judge, problem solve. Patterns put our minds at ease, and make things easier to comprehend. It's actually why conspiracy theorists manage to convince themselves and others that conspiracies exist, because we look for patterns, even where their are none. Rhyming is patterned thought in itself. When you rhyme words together to remember something, each one is connected in a very simplistic and easy way, and it puts the storage part of our thought process at ease.

ELI5: what kind of math, if any, is behind traffic lights especially in major cities? Is it a difficult process to time them in sync with surrounding lights to make sure there are no huge back ups?

Traffic engineers have models that incorporate any new lights into the existing network of traffic lights. Traffic light timing is done both to synchronize the lights with the surrounding network, but also to ensure that people don't have to wait too long at the lights. So there's lots of math behind it, but it's mostly done with computer programs.

ELI5: the notion that our physical strength is held within safe limits by pain. Are we really that much stronger than we experience in our daily lives?

To put it simply, yes, your body is capable of lifting much more than you realized. However, it can't do it without serious damage. The stories of mothers on adrenaline lifting cars are true; what they don't tell you, however, is the aftermath, where she has a number of torn muscles and had to lie in bed for a week recovering. Pain is protecting you from damage. It warns you when you're hitting your muscles' breaking point. Sure you can push past that, but you're going to do lasting damage in the process. Evolution isn't dumb; being stronger is a big advantage, so if your body is deliberately holding you back it's for a good reason.

ELI5: Why is it that when watching a movie at 24 frames per second it seems perfectly normal, but when playing a video game it is almost unbearable?

Film frames can capture motion blur of fast moving objects, essentially the object is appearing in several places at once. Video games render a series of still images of objects in a single location at any point in time (for the most part). When viewed at full speed, the motion blur captured on film is much more pleasing to the eye than a bunch of sharply rendered video game frames.

Since the honeybee is an foreign species in North America, would it really be that bad for NA if all honeybees died out?

Since honeybees are technically an invasive species, would it have much impact? How did pollination work before bees in the Americas?

Bees aren't the only pollinators; before european bees were introduced in 1600, other pollinators played a central role. But you can't feed the US of today with the technology of 1600s. Crops that depend on pollination by bees today include apples, avocados, onions, oranges, pears, and pumpkins. Eliminate everything from your life that includes any one of those, see how much is left, and then decide whether that is "much impact".

ELI5: How does ironing work?

Through a mixture of different forces. First, HEAT & STEAM- the heat and the steam in the iron makes the bonds between the molecules of the fabric weak and pliable. Second, WEIGHT- the weight of the iron makes the (now pliable) fabric press flat. When it cools, the molecule bonds strengthen again, so they will stay in their new flat shape.

Why doesn’t the LHC use an extra electric field to curve its beams instead of relying on magnets and the Lorentz force? Wouldn’t it be possible to have another electric field coming from the “sides”?

Magnetic fields are more convenient for bending/focusing elements at high beam velocities than electrostatic devices. Electrostatic methods are used for very low-velocity beams (typical v/c ~ 0.05 or less). After the pre-acceleration is done and the beam has been injected into some larger accelerator, magnetic methods are used instead. Additionally, electric fields will not just bend and focus, but also change the energy of the beam particles. Magnetic fields don't do this (neglecting synchrotron radiation, which is currently only relevant for electron beams). This complicates the dynamics. In a synchrotron, you want the energy increases to occur in the RF cavities, not also in the bending/focusing elements. And in a storage ring, you just don't want the energy to change at all.

Where does Rorty say to avoid metaphysical problems is to stop asking them?

I am reading a dissertation and writer says this: "For Rorty, the way to avoid metaphysical problems is to stop asking (and thinking about, and obsessing over) metaphysical questions. This will take time and practice, but its primary strategy is simple avoidance. For the pragmatist, nihilism takes essentialist theories of truth too seriously." (Rorty, Consequences of Pragmatism, 1982, xxxvii, xlii, 192-3 and 206-8.) But when i check the original text i don't think Rorty says or implies that thought in those pages. I am not well versed about Rorty's pragmatism, does he make that point if so in which book or article? Thanks in advance.

I don't have that book, but those later citations are pointing to parts of "Method, Social Science, and Social Hope" (especially the first few pages) where he says stuff like this: > The importance of Kuhn seems to me to be that, like Dewey, he is one of these few. Kuhn and Dewey suggest we give up the notion of science traveling towards an end called 'correspondence with reality' and instead say merely that a given vocabulary works better than another for a given purpose. If we accept their suggestion, we shall not be inclined to ask 'What method do scientists use?'...We shall not think there is or could be an epistemologically pregnant answer to the question 'What did Galileo do right that Aristotle did wrong?,' any more than we should expect such an answer to the questions 'What did Plato do right that Xenophon did wrong?' or 'What did Mirabeau do right that Louis XVI did wrong?' We shall just say that Galileo had a good idea, and Aristotle a less good idea; Galileo was using some terminology which helped, and Aristotle wasn't. Galileo's terminology was the only 'secret' he had - he didn't pick that ter- minology because it was 'clear' or 'natural,' or 'simple,' or in line with the categories of the pure understanding. He just lucked out That is, Rorty sees Kuhn and Dewey as putting an end to asking certain kinds of questions and, thus, ending the flailing which he describes the tradition as being locked in.

ELI5: Can a 'loud' sound frequency outside of our hearing range cause damage to our ears?

Sound is the vibration of an object. Our ears translate sound to our brains by turning the vibrating energy into electrical energy. They're tuned by tissue thickness and flexibility to pick up a range from 20 vibrations per second to about 20,000 vibrations per second. Sounds outside this range are still vibrating the air, which mean the ear drum is vibrating whenever any sound occurs. Too much vibration causes damage to the drum. Since that vibration goes through some bones then on to the cochlea (which has hairs to sense high or low pitch), those parts can also be damaged. Enough vibration, even though outside our range of hearing, can damage the parts that hear sounds within our normal range. To put it more simply, the ear can only detect one set of sounds, but is affected by all.

What does it mean to be a Marxist historian?

I had a professor in college (teaching a core curriculum survey of western philosophy course) who described himself as a Marxist, but when we actually did some readings from communist manifesto and das kapital didn't seem to hold it in particularly high esteem, and clarified that being Marxist didn't necessarily mean holding close to all of Marx's views. So what does being a Marxist historian probably mean to this professor, since it clearly doesn't mean a close devotion to Marx's stages of development?

A Marxist historian is a historian who interprets history through the framework of Marxism. This includes things like looking at the nature of class struggle in a particular period of time, or understanding beliefs, cultural customs, morals, religions, etc. through the base and superstructure model as time progresses. It's hard to know what exactly your professor means without elaborating more, but *The Communist Manifesto* is often not viewed as prescriptive by 2015 Marxism because it was meant only to apply to 19th century Western Europe and not as a universal model, and the majority of *Capital* is a critique of capitalism rather than a historical overview. If you're looking for a good contemporary Marxist survey of world history then check out *A Marxist History of the World: From Neanderthals to Neoliberals* by Marxist historian Neil Faulkner.

What causes people to act different when drinking than when sober?

From a medical perspective, alcohol affects different parts of the brain in different concentrations. The most sensitive area of the brain to alcohol is the prefrontal cortex. This is the area of the brain responsible for urge inhibition, planning, and executive thought. With alcohols intoxication, these processes are impaired leading to changes in behavior and poor impulse control. As you continue drinking and blood alcohol levels rise, more parts of the brain are impaired. The frontal cortex is next, leading to problems with speech, coordination, and certain reflexes (like visual tracking). After that, the hippocampus is affected leading to the inability to form memories (blacking out). If you continue to drink, the brainstem can be affected leading to depression of the reticular activating system and several centers critical to the support of vital functions. This will make you pass out and possibly stop breathing.

ELI5: Why do Asian countries have a much smaller rate of obesity than the US?

There are genetic predispositions involved in obesity, but also considerable differences in diet and culture. Obesity has been growing a lot in China, as its food supply industrializes and Western practices like using cheap, non-natural sugars in packaged foods increase. However, it doesn't seem to be an issue in Japan or South Korea, where cuisine is strongly cultural and not just based on economics. Food preparation and balance is taken very seriously, in ways that are similar to French and Italian culture, but with very small portion sizes. There is also a cultural emphasis on shame, so an obese person is more motivated to take whatever measures may be necessary to lose weight, whereas there is more of a rationalizing and individualist view in most Western societies. Shaming a fat person is unethical in Western culture while being one is ethically neutral (except in that maybe you cause people who care about you to worry for your health), whereas in Japan, being fat could be considered mildly unethical because you may be embarrassing your family and the people you're associated with.

ELI5: The universe either started at one point, or has always been there. How are either possible?

That's a concept I could never really wrap my head around. Apparently this is called the "eternity of the world"? https://en.wikipedia.org/wiki/Eternity_of_the_world The way I see it there are two possibilities: 1) Time, the universe, and everything started an one point. 2) Time, the universe, and everything has always existed. Point 1 seems illogical- it begs the question "what allowed the universe into being", which if answered just give us "then what allowed that into being". However I think about this, there must be something before each "creation". The concept that there was a state of nothingness- devoid of time, space, motion, and energy prior to the creation of everything does not make sense. Point 2 seems impossible- how could something have just been there? Surely something must have triggered it's existence. This is saying that time, space, and everything stretches infinitely backwards- so if we invented time travel we could just keep rewinding and we will see every possibility of reality forever, repeated infinitely. Either that, or the universe has just been stagnant and something urged it into motion.. which again goes back into the first point. **TLDR: If something created the universe, who created that? Is it really turtles all the way down?** Edit: Omg guys don't sneak up on me while I'm at work. Busy reading... Edit2: Okay I do see a few themes reoccur. * Point 1 is possible. We have to throw out two assumptions (1) time as something very rigid/fixed (2) something must have started it all (causality). This goes into quantum fluctuations- how we do observe something come from nothing, and Lawrence Krauss is a great place to start reading more. Here lots of people also mention we cannot talk about "before" time, by definition. It just popped into existence and we can talk only talk about "after". * Point 2 I do not see lots of support for, most people agree there must be a starting point. * Another common response is "it's unknowable". There are things which we as humans can never grasp, this may be one of them. I personally dislike this reply, I feel like it's lazy and convenient. That said I must concede that this is possible. * A final response which I absolutely love is "we may be missing an insight to be able to explain this". A great ELI5 Answer: https://www.reddit.com/r/explainlikeimfive/comments/4j57x3/eli5_the_universe_either_started_at_one_point_or/d341din Perhaps there are assumptions about time, space, or something else which needs to be broken which will show that we can't get an answer because we are asking the wrong questions. Thanks everyone for the awesome replies!

> Point 1 seems illogical- it begs the question "what allowed the universe into being" You are approaching this from a standpoint of absolute reliance on causality. Our brains are wired and designed to think of everything in terms of cause and effect - if there is an effect then we assume there must be a cause. And indeed we constantly observe cause and effect everyday around us. But there is no fundamental logical reason why an effect *has* to have a cause. To say "what caused time to start" isn't a meaningful question as in order for something to *cause* something to start, time must exist.

E: Why is it that Muslim Extremism is more prevalent than other religions?

Bit of background first so stop any aggro: I am half Kosovan (for those who want to know what that is look [here](http://en.wikipedia.org/wiki/Kosovo)), half my family is Islamic, so I'm not posting this as a vent of hatred, I simply wish to understand it further. I do have basic to moderate knowledge of the religion and it's principles/ practices/ ideas etc. but one thing I cant wrap my head around is why extremism is so prevalent in Islam. I'm not saying that it is the only religion that has it, because I'm sure a visit to the deep south in the USA will uncover some interesting Christian beliefs (as an example). What i'm trying to ask is; is Islamic extremism a by-product of Western hatred for the Middle-East? Or is it a natural divergence of Islam? I was reading [this post] (http://www.reddit.com/r/explainlikeimfive/comments/1n2u91/eli5what_are_islamic_terrorist_groups_trying_to_do/) and it gave me some food for thought. I'd like to hear from some Muslims of reddit to see your point of view, because as a result of having muslim acquaintances of difference nationalities I know for a fact their interpretations of the Qu'ran can be quite different. EDIT: Answered-ish, I feel like all comments will be of opinion rather than a fact that probably does exist, thanks a lot to all those who answered, its been interesting reading through.

Oil In the west the principle of secular government has proven to be very successful, seperation of church and state has delivered benefits in science, technology and economics which made the west powerful and hungry for oil. The cold war with the soviet union made control of oil resources even more critical. After the collapse of the ottoman empire the middle east became a series of independent states. The superpowers sought to control several of these states by setting up puppet regimes in thier own image - ie secular and liberal. At the same time in saudi arabia a new form of conservative islamic thought known as wahhabism surfaced which called for a more puritanical adherence to the koran. The oil wealth of the saudi kings was used to help spread wahhabism throughout the region through funding for madrasas (religious schools) Combined with opposition to the increasingly hardline and authoritarian secular puppet states - a new political ideology emerged known as islamism. Islamist thought called for the dismantling of a countries secular constitution to be replaced with one based on the koran. This led to some successful islamist led or inspired revololutions (iran/afghanistan) and a lot of islamist rebellions across the arab world tl,dr: Its the explicit rejection of western secularism through the political ideology of islamism that makes islam seem like such an extreme religion

CMV: "White" is a Stupid Classification term for people.

1. **Continuous Cultural Gradient.** A Sicilian has more in common culturally with a Tunisian (not "White") than he has with a Norwegian. A Norwegian has more in common culturally with an Inuit (not "White") than he has with a Sicilian. Culture (Biome adaptation, Landscape influenced Art/Literature/Cuisine/Agriculture, etc) form a continuous gradient across continents. 2. **The Arbitrariness of Geography.** Siberia is not in Europe. Are Siberian Women not "White"? 3. **Complete Irrelevance within Europe.** As White American who has traveled through Eastern and Western Europe, I implore you to see how far being a "Whitey" will get you in Europe. Fuck all is the Answer. Because absolutely Nobody in Europe self identifies as "White." Basque, Bavarian, Bosniac, Belarusian, Bulgarian? Sure. 4. **Historical Context in North America** What does "Black" even mean on this Continent? It is Label defined by English/Scottish Slave owners to destroy the ethnic identities of Hamitic, Hausa, Bantu, Mande, Nilotic, Kanuri, Songhai, Khoi-San peoples they brought along as slaves! What does "White" even mean on this Continent? It is Label defined by English/Scottish Slave owners, and Native Slaughterers to hide their criminality by grouping themselves with later arriving Innocent Mainland European peoples who were then culture shamed, religion shamed and language shamed like every other minority ! 5. **The question of who/what is MOST "White"** Almost every "White" Supremacist forum, Stormfront, /pol, ifunny, etc has continual discussion into who is Most White? Are Greeks White? Are Italians White? Are the Finnish White? Are Slavs White? Why is our national Language not German, given that they are the Largest Ethnic group in the USA? Are German Americans no AS "White" AS the English/Scottish Default? **Benefits of non Monolith-ing White America** 1. **Targeted Societal Help** Societal metrics of [Divorce](https://imgur.com/1rwmyJz) || [Addiction](https://imgur.com/f1xhTI0) || [Physical/Financial/Mental Well Being](https://imgur.com/HfTtL0l) || [Education](https://imgur.com/ts4NOtS) show the bottom rung of White society are the English/Scottish Whites ***(E/SWs)*** *who make up* *12.9% of White America.* 2. **Targeted Crime Fighting - Toxic Ideology** *America's Anglo Supremacist Alt Right:* Richard SPENCER, Jarod *TAYLOR*, Felix *LACE*, David *DUKE*, Charles *MURRAY*, Christoper *CANTWELL*, Charles C *JOHNSON*, Sean *DAVIS*, James A. *FIELDS* Jr, Andrew *ANGLIN*, John *DERBYSHIRE*, Paul Ray *RAMSAY*, Gavin *McINNES*, Faith *GOLDY*, Tara *McCARTHY (Scottish born+raised)*, Brittany *PETTIBONE*. Hacking group Anonymous provided names of [500 kkk members](https://pastebin.com/wbvP95wg). *84% of KKK Surnames are E/SW making them 35x more likely to be Supremacist than Non E/S Whites* 3. **Targeted Crime Fighting - Terrorism** *America's "White" Mass Shooters (From 2013 onwards)*: Stephen *PADDOCK*, James *HOLMES*, Devin Patrick *KELLEY*, Dylan *ROOF*, Charles *MANSON*, Robert *BOWERS*, Ian David *LONG*, Thomas Michael *LANE* III, Jeffrey T. *JOHNSON*, Wade Michael *PAGE*, Amy *BISHOP*, Christopher Bryan *SPEIGHT*, Timothy *HENDRON*, Joseph Jesse *ALDRIDGE*, Bradley William *STONE*, Elliot *RODGERS*, Frazier Glenn *MILLER*, John Russell *HOUSER*, David Ray *CONLEY* III, Chris Harper *MERCER*, Robert Lewis *DEAR* Jr., Jason Brian *DALTON*, Larry Darnell *GORDON*, Jesse *OSBORNE*, Jeremy *PATTERSON*, Randy Robert *STAIR*, James Thomas *HODGEKINSON*, Kevin Janson *NEAL*, William Edward *ATCHISON*, Seth *HOPKINS*, Gregory A. *BUSH*. Patrick Wood *BROWN*, Connor *BETTS* *93% of all "White" Mass Shooters from 2013 are E/SW* *making them 91x more likely to be Spree Shooter than Non E/S Whites.* TLDR: Pumpkins, Oranges, Carrots and Aunt Gertie's Gold Heirloom Tomatoes are the same if classified only by skin color (Orange). Thankfully they are not. Why should this be any better at classifying humans?

I would just point out that these arguments apply not just to one race, but to the entire concept of racial categorization.  All races encompass multiple cultures which overlap with other races. All races are geographically inconsistent. All racial definitions arose out of a historical context of white imperialism which is now irrelevant. All race categories are inherently exclusionary. All sociological study and policy drafting is better conducted around socioeconomic or ethnological factors rather than race.

If a bilingual person were to experience full-on retrograde amnesia, would they retain the ability to speak both of their languages?

This really depends on what causes the amnesia, and from how long ago they learned their language. However, if they were bilingual since early childhood, they will most likely retain language, even with full blown hippocampal lesions. This is because faculties like language aren't "recalled" the same way you recall a previous birthday, but are instead something deeper, and dependent on more widespread cortex.

Branching from a branch, merge to master

Probably a pretty basic question but I am working on a branch, lets call BranchA. I have a PR in for BranchA right into master, but it will take some time to get approved. I need the changes from BranchA so I can create a branch of BranchA called BranchB. I never will merge B into master before A, since I know B will contain the commits of A. But if I merge A into master, what is the procedure to merge B into master? Will it recognize that they are the same commits originally from A and just only add on the commits from B?

> what is the procedure to merge B into master? The same as the procedure to merge A into master. > Will it recognize that they are the same commits originally from A and just only add on the commits from B? Yes. The commits are uniquely identified by a hash that is shared across all branches with the commits.

How to actually learn philosophy?

I believe this is an underrated question: When trying to learn about new topics within philosophy, how do self-taught learners and graduate students go about finding resources on the subject they want to learn? I am tired of just typing “x subject books” into the google search bar because the books that google recommend are not at all what my philosophy professors recommend. Is there a method you follow if you want to learn a new subject? I am already aware of the SEP but that can not be all that graduate students or self-taught learners use. Also do most people choose to read books or papers? I was told books is common for intro level or beginners but papers are key as you get upper level.

I would search for syllabi, which can often be easily found online. If you want to know more about metaphysics, google “metaphysics class syllabus” and they usually have the university listed so you know its reputable.

ELI5: If the brain can only survive 4-6 minutes without oxygen, how can freedivers hold their breath for 8+ minutes?

And what about people like David Blaine or Tom Sietas? Sietas held his breath underwater for over 22 minutes (world record). I know they train for it like months and even years, but doesn't holding your breath = no oxygen to brain? Permanent brain damage apparently occurs just after 4 minutes of lack of oxygen to the brain, so why are freedivers left generally unscathed after 8 or 10 minutes without air?

The level of oxygen in the body is dependent on two things - how much oxygen is in the bloodstream, and how fast it can be used by the body. So in the case of David Blaine, he breathed pure oxygen for good period before his record attempt, and through practice increased the time that oxygen could last for by slowing down how much he uses that oxygen. Free divers also are helped by the body slowing down in cold water their pulse rate, and how their body uses energy. These all slow down so free divers (after much practice) can hold their breath for longer than people on dry land.

ELI5 How homeopathy is supposed to work?

I just don't get it.

Homeopathy claims to work on two principles. 1. Like cures like. 2. The more dilute the medicine, the stronger it works. Principle 1 goes like this. If substance S causes symptoms X, Y and Z, then substance S should be used to treat a disease with symptoms X, Y and Z. For example, if you can't get to sleep, and go get a homeopathic sleep aid, it's quite likely that the active ingredient listed on the box will be caffeine. Principle 2 says that once you have identified the active ingredient you want (e.g., caffeine for sleeping pills), in order to make its effects more pronounced, you should dilute it. When diluting the active ingredient, you're supposed to dilute it by ten times. That is, you put one part of the active ingredient in ten parts water and mix. Each dilution is one "x". If you look a the label of a homeopathic remedy it's not uncommon to see 20x or even 60x dilutions. Now, remember, each dilution dilutes the substance by ten times. A 20x dilution is not 1/20th as dilute as normal, it is 1/100000000000000000000th (that's 1/10^20 ) as dilute as normal. Once you get in the neighborhood of 20x dilutions there's a good chance there is absolutely none of the active ingredient left, and all you have is water. Go higher than that and it's almost certain there is none of the active ingredient present. Here's the best bit, though. At the time homeopathy was created, it was relatively beneficial. The important word there is "relatively." At that time doctors were still performing bleedings and giving patients remedies containing heavy metals like mercury. The homeopaths were actually safer, but only because they weren't actively poisoning and harming their patients. All they were doing was giving people a drink of water and sending them on their way, and some people just got better on their own. These days you would have to be a drooling retard to think homeopathy has any merits at all.

The "Wikipedia game"- does it reflect something fundamental about human language and knowledge or is it simply an artifact of the structure of Wikipedia?

Take any random entry in Wikipedia and click the first link in the text for the entry. Continue doing this long enough, and you'll almost invariably end up at the entry for Philosophy (and often, awareness and perception). I find this fascinating and wonder why this is- is it because of how humans approach knowledge and understanding, is it pointing at something fundamental about how humans perceive reality, or is it just because that's how Wikipedia is structured? Any thoughts?

Normally the first sentence of a Wikipedia article is a very high-level description of the subject, which lends itself naturally to linking towards more abstract concepts rather than more concrete particulars. So articles about places and people will link to the country they're in/from, then the countries' articles will say "X is a country" with a link to the definition of a country which leads you into law and political philosophy. Articles about technical subject matter will start by naming the field they're within, which then links up to the definition of science or math or whatever, and from there into more abstract categories. Articles about simple object nouns tend to start with the category of thing that it is... the article for which may then start with "X is a category", with a link to the notion of a category which feeds back into the abstract math cluster. Just... always moving in the direction of the abstract. Which, apparently, naturally brings you to philosophy as the ur-abstraction.

ELI5: How does information pass through the air? (ie, Wifi, television, phone calls, etc.) How did someone learn to do that? What? Science and technology literally blow my mind.

Wireless communication usually uses radio waves, which are a form of electromagnetic radiation just like visible light is. While visible light is blocked by most solid materials, radio waves can pass through most substances to some extent, which is why you can use a cell phone from inside your house (but probably not in a tunnel underground). The radio waves are created by passing an electric current through an antenna. When the radio waves hit another antenna, they then create another electric current. The electric current used to make the radio waves is varied to send specific signals, and the electric current on the other end is measured to decode those signals.

ELI5: the difference between Software Engineer(ing) and Software Developer(ment), if there is one.

Just wondering what the difference is, if there is one. It seems that people that I know in software engineering tend to have slightly different roles than other friends who are software developers. I can't put my finger on the difference though, so I thought I'd ask. Many thanks!

In general the two terms are fairly interchangeable, and the work done by a "software developer" at one company might be identical to the work done by a "software engineer" at another. If there is a difference it's that Software Engineering might try to put a greater emphasis on trying to adhere to industry best-practice guidelines. So an insistence on whatever are the current in-favour development methodologies, at the moment that would include Agile techniques such as Behaviour-Driven Development, Test-Driven Development, probably Scrum or Kanban or similar. However it's perfectly possible for someone to have a "software engineer" job title and not adhere to those methodologies.

Rubbing alcohol is often use to sanitize skin (after an injury/before an injection), but I have never seen someone use it to clean their counters or other non-porous surfaces — is there a reason rubbing alcohol is not used on such surfaces but non-alcohol-based spray cleaners are?

Edit: Whoa! This is now my most highly upvoted post and it was humbly inspired by the fact that I cleaned a toilet seat with rubbing alcohol in a pinch. Haha. I am so grateful for all of your thoughtful answers. So many things you all have taught me that I had not considered before (and so much about the different environments you work in). Thank you so much for all of your contributions.

Alcohol used to be the antiseptic of choice for instruments and surfaces in healthcare settings. It remains so in some countries and settings. Alcohol was only replaced because it was ineffective against spores and some viruses.

ELI5: Why does it seem like people are more religious in rural or impoverished areas?

Just something I noticed while driving through a lot of small towns this weekend. A lot of the signs for the city had a list of all the churches.

There are multiple reasons that all contribute. Religion gives people hope, and is something to lean on in hard times. Another is that smaller towns generally don't have enough of a population to support parks, bars, nightclubs, or theaters. Which means that the churches take on the role of gathering spots within those communities. Rural communities also tend to be more conservative, and churches are an old institution. So it's more acceptable in the community to spend money on an old institution than a new on.

What are the differences between waves?

I hear sound waves, I see light waves, and I would feel micro waves if they were in a high enough concentration. So what is the difference between then?

Light waves and microwaves are the same, just at different wavelengths. They are both examples of electromagnetic waves. Sound waves are just the motions of compressed air. A vibrating object will cause the air around it to compress and then decompress as it moves towards the air and then away. We call things "waves" if they obay the mathematical "wave equation" which you can google. It is a partial differential equation that relates how quickly things are changing in space are connected to how quickly things are changing in time. It turns out the intensity of light and how light moves follows the same rules as the volume of sound and how sound moves. Just with a different underlying thing changing (air pressure or strength of electric fields) and different speeds. But the math for both work the same so we call them both waves.

ELI5: Why can't a single blood test show you all the information you need instead of having to take multiple tests for different markers?

A blood test looks at the number of molecules or ions in a specified volume of blood. To get this information, you need to mix the blood with different chemicals to draw them out before processing them. This is why different blood bottles exist, because mixing with the wrong 'reagent' will produce errors. Even the most basic (common, not necessarily easiest) blood test like kidney function is still looking for four things: urea, creatinine, sodium and potassium. They all get processed off the same bottle helpfully, but if you wanted to do a full blood count (haemoglobin, white cells etc etc) that's a different bottle and will give you upwards of 8 different numbers depending on the lab. TL:DR - most blood tests are actually lots of results rolled into a list. There a far too many things in the blood to look for everything every time, it would cost tons.

I believe that it is extremely, extremely, extremely unjust for the media to follow a court case, provide a perspective on it, and show the face of the person on trial. Please somehow CMV.

I could not feel more strongly about this. It is absolutely ridiculous that a person before they are innocent or guilty has their face shown to the public and therefore associated with a crime. It's completely ridiculous and mind numbingly preposterous to think that a possibly innocent man accused of rape has their face shown, accused of murder has their face shown to ignorant people who take the media on face value. The person, because of the media spreading their face, is now under threat from the general public. People who may have only seen the first headline and think they did it. If a man is convicted of rape or murder of a child, then is proven innocent, already their face has been shown to people in that community. The people who don't consider the evidence or respect the outcome, who remain ignorant, now will hold no restraint in thinking it is "just" to beat the shit out of him. Because ignorant and easily influenced people want to play "hero" and attack the guy they think is bad guy to get some cheap "look how much of a hero I am" kicks. The person whether guilty or innocent is publicly shamed and now prone to attack eg Zimmerman, the "Dingo ate my baby" (Azaria Chamberlain) case. Azaria Chamberlain, when I read a news article about it, was one of the most heart breaking of these. This poor mother lost her child, and was criticised for not showing enough emotion. Because she wasn't "likeable" by the general public because she didn't provide them with the expected exaggerated crying and emotion, there was ridiculing of her story by the public and media in Australia which influenced the court case itself. (If you can, provide me some more examples and I'll make a a list.) Isn't there a law that makes public defamation illegal?

There are two arguments against your position, which may change your view. Firstly, publication of who has been accused of a crime can allow other victims to feel like they can come forward. In the UK, the most prolific paedophile for decades was a 'well-loved' celebrity called Jimmy Savile. He operated with impunity for years, until the first real public investigation began. Then literally hundreds of victims came forward. All people who had believed the lie that they were weak and no one would believe them. Individually they were too frightening to come forward. Together, they have shone light on horrific crimes, and - albeit too late - the truth has come out. Secondly, public trials allow scrutiny of the judicial system, review of the state's power, a guard against corruption, and allow the public to see justice done. This ought to strengthen the community, give people faith in the justice system (which should guard against vigilante attacks), and deter future crimes - as potential criminals can see that they too could be brought to book.

Why does a half dozen eggs cost almost as much as a dozen?

Two potential reasons, which may be interlinked. 1. The marginal cost to extra eggs is very low therefore moving from 6 to 12 eggs costs little in terms of extra materials or transport costs 2. Supermarkets overprice the half-dozen eggs to induce customers to buy the dozen as it's better value. I'd bet it's more likely to be number 2.

ELI5: Can someone explain the 2022 nobel physics winner’s experiments and what they prove more simply?

Quantum mechanics is a well established theory, but predicts many weird effects. One of these is that particles can become "entangled"which means that they share some properties. Then these particles can move apart, but the entanglement is retained. If we measure the property of one we will know instantly the property of the other. So far so simple, but the key thing is that the particles don't have the property in common, and we just look at it. They exist in a superposition, meaning it could go either way. Then the act of measurement "collapses the wavefunction" meaning that the measured particle randomly "chooses" which option it has. That information is then passed instantly to the other particle, violating our understanding of how information can only travel at the speed of light. One way to avoid this contradiction is to invoke "hidden local variables". Basically we say that maybe the two particles do actually agree on which way they will go ahead of time, and that information is stored in the hidden variables. This is great at avoiding the contradiction (preserving "local realism"), but isn't actually predicted by the scientific theory. Someone called John Stewart Bell pointed out that under certain conditions a pair of entangled particles would behave differently under standard quantum mechanics vs if hidden variables are real. This allows an experiment to be set up to test which theory is actually real. One of the winners, Clauser, was the first to do such an experiment, but the setup had flaws called "loopholes". Another winner, Aspect, closed some of them. It has taken 50 years to be confident we have closed all the loopholes and that local hidden variables don't exist. So the result is to confirm that this aspect of quantum mechanics really is as weird as it seems, that entangled particles really do "communicate" faster than the speed of light. The way that the experiments were set up varies widely, so it's a bit hard to explain all of them. Basically you measure a bunch of entangled particles and see how the random distribution turns out.

I'm Chris Blattman, economics and political science professor, and I just published *Why We Fight* a book about everything we know about global conflict. AMA!

Hi, I’m Chris Blattman from The University of Chicago’s Harris School of Public Policy. My book [Why We Fight: The Roots of War and the Paths to Peace](https://chrisblattman.com/why-we-fight/) publishes tomorrow April 19th. [Proof](https://twitter.com/cblatts/status/1516042751183400965?s=20&t=zThno_trYkiVyn4to4hpxw) I’m an economist and political scientist. I’ve worked in civil wars in East & West Africa, and with gangs in Colombia and Chicago. My book looks at fighting of every kind—from civil conflicts and gang wars to ancient Greece and the World Wars, plus the kinds of invasions we are witnessing now in Ukraine. [Why We Fight](https://chrisblattman.com/why-we-fight/) walks through the psychological and strategic forces of war, especially the ones we tend to overlook. It’s easy to forget that war shouldn’t happen — and that most of the time it doesn’t. There are millions of hostile rivalries around the globe and yet only a fraction erupt into violence. That's because war is ruinous. War is what happens when something keeps rivals from weighing the brutal costs of fighting. The book looks back at decades of social science and shows that there are really just 5 ways this happens: 1. *Unchecked interests.* When leaders aren't accountable to their people and ignore the costs, or seek private gains 2. *Intangible incentives.* When groups value something ideological or intangible that only war will bring 3. *Misperceptions.* When groups misperceive themselves or their enemy 4. *Uncertainty.* When their opponent's strength and resolve is uncertain 5. *Commitment problems.* When an opponent is expected to grow strong and can't commit not to use that strength in future I've also worked on poverty alleviation, cash transfers to the poor, sweatshops, and randomized control trials for poverty and violence reduction. Happy to answer questions on and off the topic of conflict. I a longtime [international affairs and development blogger](https://chrisblattman.com/blog/) and happy to cover any topic I write about there: academia, development, or career advice for young people. Ask Me Anything! (I'll be collecting questions this morning then start responding midday Central Time.) **Edit**: Thank you all, I had a great time answering all your questions. Thanks for participating and you can always ask me anything about econ, politics (or ducks and minecraft) [on Twitter](https://twitter.com/cblatts). You can also [subscribe to blog posts by email](https://chrisblattman.com/blog/). I’ll do my best to come back to some of the unanswered questions if I can later on

As someone (possible) giving advice to policy makers, how do you balance giving evidence based advice versus advocating for broader reforms which may or may not have been tried but have higher upside?

ELI5: Why is it that when I look at the moon with my naked eye it's huge, but when I take a picture of it with my digital camera it's a tiny dot?

There are two reasons for what you described. The reason the moon can look so big to your eyes is that it is usually low on the horizon when you notice it and there is some far off building/trees/skyline that gives your brain a reference for size. The image on your retina is exactly the same but your brain sees it as "bigger" because it now has a way to measure it against something familiar. If you look at the moon when it is straight overhead it is the same size but will look very small in the open sky (unless a plane goes in front of it). The reason the moon looks small in photos has to do with the angle of view given by the lens. A "wide" lens has a short focal length, giving you ~60 degrees of the sky visible. The moon however only takes up 1/2 of a degree of the sky, with a 60 degree view the moon takes up 1/120th of the width of your picture and there is no fooling your brain into making it look bigger. To take a picture where the moon looks big you need a lens that has a very small angle of view, only a few ones of degrees, but those lenses tend to be very expensive, a few thousands of dollars. A lens with a 2.5 degree angle of view will make the moon cover 1/5th of the width of the photo, quite a bit bigger than the 1/120th of a normal angle of view.

Since the speed of an electrical signal remains the same, why is there still room to increase bitrate when transferring data?

the information is carried by the electrical signal changing strength (this is a simplification - still holds strictly true for frequency modulation, but it gets a bit more complicated) so, bit rate is increased by changing how fast the strength of the signal changes. the amount of time it takes the START of th information to get from point a to point b will remain the same, but the amount of time needed to send x amount of changes in the signal is what can be increased. Think of it like a water hose, where yu are sending morse code by turning the water on and off. the water takes the same amount of time to travel, but if you turn it on and off faster, you can send code faster. (Ok, again, an over simplification that ignores the fact that gas trapped in the hose can get compressed, but ya'll get the idea)

ELI5: why do animals at the zoo often look very healthy and in shape, despite a relatively sedentary life style?

I don't see the Tigers running anywhere, but they're still relatively healthy in weight. I also notice monkeys virtually never look fat, and more often than not, look plain muscular. Yet the humans there are always super fat. What's the deal? It must be more than just diet.

The animals get exactly the right food, in exactly the right amount and they are very closely supervised and monitored by animal medical experts. If the humans lived in a cage where the only food they had to eat was the food their doctor thought would make them the most healthy, they would not be fat. If the humans had nothing to do all day except play with enrichment items provided by their doctor to enable them to work out and maintain muscular physiques, they would look muscular.

How did Schopenhauer manage to form a pessimistic philosophy while he was an utmost fan of Vedanta?

The core of Schopenhauer's philosophy was the 'Will', which I think in layman's term can be described as an evil force at the heart of everything. However, he also was an avid fan of Indian religion school Vedanta (the philosophy of the Upanishads). Vedanta, for layman's term, states that the heart of everything is the Self. 'The Self' is pretty much the opposite of Schopenhauer's 'The Will'. The Self is Sat, Chit, Ananda (existence, consciousness, bliss). It is believed that those who are enlightened beings and abide in 'The Self' are in the state of constant bliss. ​ So I was wondering if any of you could shed a light on that.

So, two things here. Schopenhauer doesn't privilege the Upanishads over his other sources in his thought, which include strands as diverse as Kant, Plato and Karl Friedrich Krause. On a very simple understanding, Schopenhauer is simply borrowing monistic concepts from Hinduism and integrating them to his own thought, while also constructing his pessimistic edifice from Kantian and Platonic sources. It's obvious he isn't a mere regurgitator of the Upanishads, despite his profound respect for them. Second, its anachronistic to assume that the Upanishads are exemplified in the thought of Advaita Vedantism, which is a tradition that comes long after the work Schopenhauer was actually acquainted with. ​ Schopenhauer's primary engagement with Hindu thought (especially the Upanishads) came through an understanding of these texts as containing doctrines that supported Samkhya-Yoga thought, a tradition described as monist-dualism in the Encyclopedia of Indian Philosophies' volume on Yoga. If you read through Yoga and Samkhya texts, and relate them to the Upanishads, you see where Schopenhauer's position comes from, especially the distinction between prakriti as dynamic matter that consists of all objectivity and purusa as pure self-consciousness, and meditation and "higher cognition" in order to liberate oneself from bondage to prakriti and become purusa i.e. pure subject. Schopenhauer also relies on multiple Upanishadic sources which talk about the stilling of desire as opposed to positive bliss, a theme that was common in classical Indian philosophy (it was a huge controversy in the Nyaya darsana, though there's no evidence Schopenhauer had any engagement with literature of that school.) ​ In fact, Schopenhauer seems to have not had engagement with some Upanishads which parallel his position, for example the Katha Upanishad and its discussion of Naciketas being sent to Yama, the god of Death. ​ Furthermore, towards the end of WWR, Schopenhauer describes the state of pure subjectivity where the will is quietened as akin to a bliss that would appear to those still caught in the veil of maya as nothing, but to the liberated subject as everything.

Do philosophers often believe that there is an objective truth?

And the statement - There is no objective truth. Is that subjective or objective?

>Do philosophers often believe that there is an objective truth? Most Philosophers believe there are objective truths about things where it's controversial to think there are objective truths, like morality. For normal boring truths about concrete objects the agreement is going to be near universal.

ELI5: Why are different actors credited in different ways during the credits of TV shows? For example, "Starring Actor A, Actor B, Actor C, featuring Actor D and Actor E, with Actor F and Actor G, guest starring Actor H"

The only one I really get is "guest starring", but what's the difference between "starring", "featuring", and "with"?

Each actor wants their billing to be as prestigious as possible, and will often negotiate in their contract for a certain type of billing. "Starring" at the front of the credits is obviously the most desirable. Sometimes, an important actor with a lot of leverage playing a non-starring character will get *last* billing that is somehow distinguished; for instance, in the credits of Buffy the Vampire Slayer, the established actor Anthony Stewart Head is billed last as "with Anthony Stewart Head as Giles". The rules and guidelines for this are arcane, and it would be nice if someone with a more thorough understanding of them could explain in greater detail.

ELI5:How a Quantum Computer works, and why it is superior to our current computers.

Quantum physicist here - a classical computer encodes information in bits, which can either take the value 0 or 1. A quantum computer instead uses a qubit, which physically can be something like a photon or an atom. The qubit can be in the state 0 or 1 (like a classical computer), but also in a superposition of these two states. Say we have a sequence of three classical bits, then we can only store 1 out of 8 possible numbers at a given time. However if we have a sequence of three qubits, all 8 numbers can be stored in a quantum superposition at the same time! This gives the quantum computer great power, because it can perform calculations on these superpositions in parallel. A system of N qubits can make 2^N calculations at the same time. So our system of three qubits make 8 calculations simultaneously, while the classical computer is only making one. This computational power means that large tasks can be performed 2^N times as fast, and there are special algorithms for things like factoring large numbers (Shor's algorithm) and searching databases (Grover's algorithm) that are only possible with a quantum computer. The main difficulty in making a quantum computer is that whenever a quantum state is measured, it collapses. So we must find a way of making the qubit perform calculations, which we do with quantum gates, and then measuring it without destroying the state. This is done in complicated ways by a process called entanglement, which for now is difficult to do with many qubits. (However this destruction of the state is sometimes useful for cryptography, because it allows the receiving end to know whether someone has looked at the information somewhere along the path. If someone has seen it, the state is destroyed and they know that their information has been breached). The qubit is also easily affected by the environment, called decoherence, and so many accidental errors occur when making computations. This is what most research is about and because of these difficulties, the quantum computer is still quite a few years off. Tl;dr - Quantum computers are super fast because they use qubits to perform multiple calculations at the same time. It is also useful for carrying secret information, beause it is immediately obvious if someone has seen it. Both of these are impossible with classical computers.

Where does the energy released from nuclear fusion come from?

I read [this post](http://www.reddit.com/r/explainlikeimfive/comments/1hjb7m/eli5_nuclear_energy/cauz0oo) about nuclear fusion and I am curious about the "massive amount of energy" that is released when a fusion reaction successfully occurs. From my knowledge, which is far from extensive and possibly wrong, the energy from a fission reaction is the result of the bonding energy within an atom being released when unstable atoms split into multiple daughter atoms. That would mean it would take a significant amount of energy to create this large, unstable atom in the first place, which is fusion. If the atoms are using the input energy as bonding energy, where is the excess energy released from fusion coming from?

Fission and fusion both work the same way: by reconfiguring nuclei into more stable groupings. Fission does so by splitting apart big nuclei, and fusion does so by combining small nuclei. But either way you do it, the end product will be more stable than the reactant(s). The more stable product will require less binding energy to hold it together, and will release the excess binding energy that it no longer needs.

ELI5 If Staphylococcus is literally on our skin, and it’s so dangerous and aggressive, why don’t we get staph infections every time we get any cut, scrape, etc?

First, Staphylococcus is a genus with many species, most of which do not cause infections. For example, S. epidemidis is very common on your skin, but generally does not cause infections. Even within the species of S. aureus, which is the one that causes lots of infections, there are strains that are worse than others. In general though, it is because your immune system is pretty good at getting rid of any bacteria that get into your body through a scrape or cut. There has to be a fairly high concentration of bacteria in the area to overwhelm the immune response to cause a clinically significant infection, and the amount of bacteria normally present on your skin isn't high enough

ELI5: If heat travels in space, why do we think things close to the Sun still freeze?

I'm reading Apollo 13, and they keep talking about how they need to be careful of the Sun overheating their ship on the way to the Moon. But in so many movies and media, it all shows people/objects/water freezing in the vacuum of space. Why does the ship need to be protected if things are freezing? Edit: I think I get it - radiation causes things in view of the Sun to still heat up, and things not facing the sun freeze in the vacuum. With liquids in a vacuum, they boil, giving off heat until they have no heat left, and then they freeze. A person would do the same - our body would try to exert as much heat as possible, which would cause us to overheat, but then we'd run out of heat, and freeze. If any part of us was close to the Sun (like how close the Earth or Moon is), that would also overheat due to radiation, and burn. Is that right?

What travels through space is electromagnetic energy. Visible light, heat (infrared), radio waves, microwaves, x-rays, gamma rays...all of these are different kinds of electromagnetic energy. A ship in space near Earth will get hot from the sunlight just like stuff on earth gets hot when you leave it out in the sun. The object absorbs the energy coming from the sun and it becomes heat (infrared). But here's the tricky thing. Here on earth, we see that hot objects will cool down pretty quickly if you just leave it in a cooler place. The heat leaves as both infrared radiation (like if you hold your hand close to something hot and feel its warmth, that's infrared), and also through conduction into other things. Everything is surrounded by air which will take in some heat, and so will the surface that the hot thing sits on (like when a hot mug of tea makes the table warm.) In space, there is no air or table. So the ship still radiates infrared like anything else, but but it can't also conduct heat away into other stuff. As long as the ship is fairly close to the sun, it will need to use reflectors and rotating parts to keep to stay cool. But the farther you go from the sun, the weaker its energy is. At some point, the ship will radiate out its heat faster than the sun warms it. So in this case, the ship will need a source of heat on board to compensate. Without an internal heat source, anything that loses heat faster than it gets warmed by the sun will indeed freeze.

For every poisonous item on Earth, do we know it is poisonous because someone tried to consume it and died? Or is there a way to know a substance is lethal without the trial and error?

We have the Universal Edibility Test, and it was probably used by people of the past as well. Here are the basic steps: 1. Separate the plant into its various parts—roots, stems, leaves, buds, and flowers. Focus on only one piece of the plant at a time. 2. Smell it. A strong, unpleasant odor is a bad sign. 3. Test for contact poisoning by placing a piece of the plant on your inner elbow or wrist for a few minutes. If your skin burns, itches, feels numb, or breaks out in a rash, don’t eat the plant. 4. If the plant passes the skin test, prepare a small portion the way you plan to eat it (boiling is always a good bet). 5. Before taking a bite, touch the plant to your lips to test for burning or itching. If there’s no reaction after 15 minutes, take a small bite, chew it, and hold it in your mouth for 15 minutes. If the plant tastes very bitter or soapy, spit it out. 6. If there’s no reaction in your mouth, swallow the bite and wait several hours. If there’s no ill effect, you can assume this part of the plant is edible. Repeat the test for other parts of the plant; some plants have both edible and inedible parts.

[Star Trek] Why doesn't Starfleet and the Federation simply use ballistic weaponry to defeat the Borg?

Since the Borg are vulnerable to ballistic weaponry (as seen in Star Trek: First Contact) then why doesn't Starfleet and the Federation simply outfit their ships and personnel with ballistic-based weaponry, as opposed to energy-based weaponry? If Starfleet/the Federation used weapons more akin to those used in Battlestar Galactica or by the UNSC in Halo, then the Borg wouldn't be able to adapt to their weaponry, and Starfleet/the Federation would fare much better in the fight against the Borg. I could be wrong, but I think a single MAC round from a UNSC frigate could rip a Borg sphere in half, and a volley of several MAC rounds from several UNSC vessels could tear a Borg cube to shreds.

Remember that the primary tactical advantage that the Borg possess is their ability to adapt. The shields they use on their ships and by their drones aren't just physical barriers like the traditional force fields used by Starfleet and other species, but rather they are sub-space fields designed to *absorb* different types of energy and direct it harmlessly into subspace. This is why we often see those who fight against the Borg trying to come up with new weapons frequencies to use against them, because once they've adapted to one energy frequency they can adapt to protect against that frequency extremely quickly faster and faster, so even if you change frequency and go back again, they've already adapted. This is also why when during the Enterprise's assault on the Borg cube using their deflector array (TNG: Best of Both Worlds part 2) it is ineffective because the Borg assimilated Picard and he knew the deflector frequency. The Enterprise channeled a *massive* amount of power into that blast (virtually all the energy from their warp core), any conventional shielding system would have been overwhelmed, but it didn't matter how much power they put behind it because the Borg had already adapted to the energy frequency. They could have fired all day long and it wouldn't have made a difference. So let us consider projectile weapons such as the gun used by Picard during First Contact. The reason it worked was because in a galaxy where seemingly all space-faring civilizations are using energy-based weapons it makes sense that the Borg would pre-configure their adaptations to be against energy based weapons. Picard's sudden use of a projectile weapon caught them off guard. If the crew of the Enterprise suddenly re-equipped themselves with tommy guns, the Borg would reconfigure and adapt to protect against kinetic energy, and that would be that, because kinetic energy only has one frequency; you cannot "re-modulate" a bullet. **TL;DR:** The Borg can adapt to different energy types and frequencies. Projectile weapons only have one kinetic energy frequency. Once the Borg adapt to it that's it, you cannot re-modulate a bullet. Picard was able to kill the drones in First Contact because caught them off guard; they were pre-configured towards protecting against energy weapons.

ELI5:How do shows like Orphan Black, who has a actor who plays multiple roles, show the same actor playing several different characters interacting with each other, in the same shot? (example inside)

For example this screen shot from Orphan Black: https://i.imgur.com/KgRa566.jpg (all three of them are the same actor) I assuming green screens and multiple shots, all edited together, but i could be wrong.

In scenes where you see the actor interacting with herself, you've got a few methods at work. Sometimes they shoot the same shot multiple times with the same actor then overlay them digitally which puts them all in the same shot. They use stand ins when filming so she doesn't have to look at dead space or a tennis ball on a stick. They can also digitally add her face over the stand-ins but that's a little more difficult to do and doesn't look as good as the above technique.

Does fractional reserve banking create new money?

The explanation I have heard is that Alice deposits $1 into the bank, the bank lends $1 to bob, there are now $2 in the economy so the bank created $1 out of thin air. This explanation however doesnt make sense to me. Alice cannot actually use the $1, if she tried to withdraw it the bank would not be able to provide it to her because bob has it. So in reality there is still the same $1 in the economy. Is my understanding correct or do banks really create money out of thin air?

To understand what’s going on, you should familiarize yourself with the different measurements of the money supply. In particular, have a look at the M0 (coins and notes) and M1 (demand deposits). When the bank lends $1 to Bob they credit Bob’s account with $1 increasing the M1 money supply by $1. Now Bob can buy something from someone else by transferring the $1 of M1 from his account to some else’s account. Bob doesn’t need to withdraw cash to pay this second person. The whole transaction does not involve M0. As you can see, the M1 money supply can be used for purchases without going through M0. In a sense, M1 works exactly like cash. In fact, M0 is a minority in the total money supply. Currently M0 is almost 10 times smaller than M1. In reality the picture is more complicated as banks will need to keep certain amount of reserves, follow prudential regulations etc.

ELI5: How do wild animals know what is safe to eat and what is not?

Let's say you're a bear growing up somewhere in the tundra. How do you know which berries are OK to eat and which are poisionous? If it is something "taught", then are there studies about orphaned animals in the wild eating foods which are potentially poisonous?

Smell and taste warn both people and animals what is poisonous and what is not. There are some things which are hard to identify as poisonous because they have no telltale smell, taste, or appearance, but most things warn off people and animals. The aversion to the smell and taste of poisonous objects is driven by evolution, since only those who found poisonous objects awful in taste or smell would survive to pass on their genetic traits. The natural instinct to detect poisons in humans has decreased precisely because humans learned to communicate and pass down their knowledge. While decreased, vestiges of this instinct is still obvious. The smell and taste of rotten food is awful to us. Our taste buds developing the ability to taste bitterness is also a consequence of this evolution.

ELI5: Has acting in movies gotten better throughout the years, or is there some sort of "recency bias"?

I am currently watching the first Terminator and for the thirty minutes I've been watching, the acting through multiple parts have just been awful. Not only that but when looking at even older movies, the acting just seems, unnatural. Why? Has acting lessons gotten better through the years? If so, why? Will acting continue to get better? I remember getting into an argument with a roommate about it and saying "you can't act better than making someone believe you're not acting". So do we have a skewed perspective on acting based solely upon experience with movies and such?

First, there are "trends" in acting, because successful acting is ultimately about an interaction with audience expectations. Back when the stage was still the centerpiece of acting, actors were trained to be far more theatrical and audiences expected that. More natural performances weren't always the standard everyone looked for. And, sometimes they still aren't---just look at a movie like, say, The Rundown. The acting there is great, but very few people in that film are going for emotional realism in all their scenes, if any. And, second, there is something of a recency bias because people change. What might seem like a reasonable emotional response to someone from 1940 might read false to us today, because they way we interact with others and express emotion has changed. And, all that said, Terminator is hardly known for its spectacular acting. There are plenty of films, much older than Terminator, where most people would argue the acting holds up pretty well.

ELI5: Why do humans think other sentient beings would use radio signals to communicate with other intelligent life?

What if radio waves are a human exclusive invention, and sending these signals out are a waste of our time? Please someone ELI5.

Most of scientists who are looking for other species, accept that other species might use other methods of communication but since WE don't have access to those methods, radio is our best option. The scientists looking for radio waves aren't expecting all other life to use radio waves but they are hoping that if we stumbled upon radio as one of the best ways to transmit long distances, then it's logical to assume that someone else might have stumbled upon it as well. Additionally radio is a relatively low tech solutions so they are also hoping that, even if this imaginary race moved beyond radio waves to something else, they might recognize that others haven't advanced that far and still use radio to send a message. There's no denying that it could all be a waste of time though but until we are able to detect other signals that are capable of traveling hundreds of light years it's the best option we have to find other life.

[Halo] What exactly does a gravity hammer do?

To me it appears to just be a big hammer smashing people and has very little effect in the gravity. It lights up and makes a loud noise so it's doing something but what?

Gravity hammers are equipped with a gravity field generator that can emit a kinetic pulse which lets it affect gravity in a small area. If you've been lucky enough to see a gravity hammer in action, you might have noticed it often results in those nearby being pushed away from the point of impact, and if you've been unlucky enough to see what happens to a person who is unfortunate enough to *be* the point of impact, you know that the damage is considerably greater than what would be possible with an ordinary, if very large, hammer. Of course, how exactly the generator works is a matter of debate among academics as any working gravity hammers would be in ONI's possession and they aren't particularly fond of publishing the results of their studies, but the lighting up and loud noise is assumed to be part of the ordinary function of the generator.

[Warhammer 40k] How much of their personalities do Space Marines retain?

I’m your average pre-teen hive-scum and one day after an especially fruitful day of stealing twice digested mutant rat flavored rations from my neighbor when I was suddenly kidnapped by a giant hulking space man. I’m sitting here on my way up to the terrifying sky-fortress and I was told in fancy-gothic something about there being surgery waiting up there for me that will make me just like them. I can see so far that all these space men act the same. Is this a culture that they develop amongst themselves or does the surgery change their personalities directly? And if it will change my personality directly will I be 100% a different person or will I keep small things like my favorite color and how I like to smear sewage mud on my face to fall asleep?

Very nature vs. Nurture problem, but you will retain plenty of stuff that remains the same in your brain. Of course they change and add thousands of things over years, so the process itself is both nature- It might kill you and only some survive. Not to mention the ENTIRE point of the process is to change everything about you including your personality. And Nurture, they have tons of physical and mental techniques to mold you into the person they wish you to be. How much of your past you meat/mental is left? Hard to say, but I'd dare say not a whole lot.

How accurate is "The Origin of Species" by Charles Darwin?

I'm just wondering if it still fits with our modern understanding of what evolution is. What did he get wrong? What did he get right? etc. EDIT: Grammar.

Well Darwin didn't know about genetics , so he had to guess about a heritability system. He also didn't have all the fossils we have now and mentions that the lack of fossils is a problem. But you could see both of those more as predictions that came true rather than mistakes.

ELI5: if being Jewish is a race or a religion?

I work with some Jewish people (not very well, don't know them enough to ask), both who have converted to Judaism, leading me to believe it is in fact a religion that one can opt in and out of. But I go to school with a girl who was "born" Jewish but is not practicing. She said that in the community she is still considered Jewish, and that it is not something you can choose not be if you are born into it. Is it a race, religion, or both? (I hope this isn't an insensitive question)

Both. Kind of. Firstly, it's worth pointing out that what we consider races are really one of about five groups: black, white, Asian, southeast Asian, or Amerindian. <EDIT:> **Most** <END EDIT> Jewish folks are an *ethnic* group that most would consider white. EDIT 2: There are significant numbers of Jewish populations in India and Asia, and they are...well, primarily Indian and Asian populations. There are also Jewish populations in Eastern Africa made up of Africans. But the primary population of people that we would identify as "Jewish" are those who arose from a population of Mediterranean Arabs betwen 5 and 6 thousand years ago, and began their primary diasporic wanderings 3,000 years ago, with another massive spread about 2,000 years ago. Ethnic Jews (of whom there are many subtypes) have certain genetic traits, just like ethnic swedes or Italians or Koreans. These traits are the result of, just like all other groups' traits, thousands of years of interbreeding with similar people. An ethnic Jew might not be a religious Jew, though. Judaism as a religion is one of the three monotheistic relations that grew out of the eastern Mediterranean, and it's the oldest. Judaism as a religion exists outside of ethnic boundaries, although there is a lot of overlap that is not seen in the other large religions (I do not consider Zoroastrianism to be large). Judaism can be practiced by ethnic Russians, Zulus, or any other group that wishes to convert. And of course there are different flavors of Judaism, just as there are different flavors of Christianity. Hope that helps!

[General Sci-Fi with Space-faring] Why do many stories involving space fleets use the command and organizational structure of a modern water-borne navy, instead of an air force or space command?

Is this a throw-back to early Sci-Fi before an air force or space program was a separate entity in it's own right? Or is it because it involves the operation of massive "ships" that are more akin to ocean vessels than aircraft? Or something else entirely?

In most cases it's a legacy effect of the operation of ships. Large space-borne vessels tend to be more like submarines than planes (even though the comparison is still relatively superficial) but fleet of starships also tend operate in formations and conditions more akin to naval behaviours than Airforce. There may also be an element of redundancy to it. Once you have a space fleet, there's no reason to have an aquatic navy. It just stops being particularly useful. However, an planetary air force remains useful in dealing with atmospheric incursion and general security. So, there may have been a conversion, similar to what happened with Cavalry, where the name 'Navy' was simply passed over to the next nearest comparison after it's original role became obsolete.

What significant movements of thought have come after/rejected postmodernism?

I'm trying to wrap my head around the history of intellectual thought (specifically in the last 20th/21st centuries) and so far haven't come across any significant movements or thinkers/writers whose beliefs are not in some way derived from the works of Foucault, Derrida etc. This is entirely due to my ignorance of a vast field of knowledge to which I'm relatively new, but very eager to learn more about. If you can recommend any particular writers or works, I'd be very grateful!

At most, "postmodernism" in philosophy is a term given to various philosophical critiques, each drawing on the resources of modern philosophy, which occurred in France in the mid 20th century. Strictly speaking, there is no such thing as a postmodern philosophy as some kind of philosophical view after modern philosophy in the way that implies. It is, at most, a group of modern philosophers critiquing some concepts of modern philosophy in different ways, and thereby still modern philosophy and not some view after it. > If you can recommend any particular writers or works, I'd be very grateful! Gary Gutting's *French Philosophy in the Twentieth Century* will give you a better topography of the intellectual movements that informed those critiques and therefore a better grasp of how 'postmodern philosophy' fits within the broader trends of modern philosophy prior, concurrent, and after it.

ELI5: How are internet sites allowed to possibly provide adult content that minors could watch by simply placing a button on their site that says "yes, I am over 18?"

The laws (obviously this varies by country) require that there be some barrier to entry. They don't specify what the barrier should be, so naturally many business choose to go with the bare minimum to obey the law. Remember the harder you make the test, the more effort your legitimate customers have to go through to get in too. That could cost you business, plus more complex solutions cost time (and therefor money), also bad. Practically, its virtually impossible to get anything more effective than what we currently have. When you try to walk into a bar you get carded, the guy at the door checks your ID, he can see you, the ID, decide if its fake, or not your ID. Online, what are they going to check? What could they possibly ask for that couldn't be faked? Edit: specific=/=specify

How important is it to dress formally for an interview?

I have an interview coming up in a day or two, for a clinical researcher/PhD position. The interview is surprisingly in person instead of on Zoom. And I'm wondering how important it is that I dress formally? It's not anything like an interview weekend or a campus visit, but more strictly like coming and sit down and we'll have a chat type of arrangement. Every sane person has told me I should wear a nice dress or at least a nice blouse, but I kind of don't feel comfortable in those clothes (I would look like a kid in adult's clothes). The weather will be relatively warm so I can't go with my usual shirt+pullover plan either. Suggestions? Any advice/comments welcome!

Treat this as a job interview and select an outfit for that purpose. Just because you feel that you might "look like a kid in adult's clothes" doesn't mean that's the way you will be perceived. Furthermore, you don't want them potentially to remember you as the only person who was interviewed and didn't dress appropriately.

How does the body decide where to store fat?

In general, females seem to store fat around the hips and thighs, males around the gut. Why? How does the body decide where to store fat?

Beyond the generalized sex differences, there are a number of hormones that affect where and how we store fat - for ex. estrogen encourages the more 'classically feminine' fat storage patterns (hips and thighs) whereas stuff like cortisol and insulin production lead more to belly fat. As the latter two, cortisol in particular, are highly stress-dependent, people may even notice different fat storage patterns at different stages of life, depending on things like diet and levels of stress or of sex hormones.

ELI5: What's P < 0.05 mean and why does it make everybody feel so confident?

In statistics, you're usually doing something called *hypothesis testing*, which relies on something called a *null hypothesis*. For example, after flipping a coin a few times and getting heads each time, you might wonder if the coin is loaded. Your null hypothesis is the *opposite* of what you're trying to prove - if you're interested in showing whether the coin is loaded, your null hypothesis is "the coin is fair". After you develop this hypothesis, you flip the coin 10 times, and get 7 heads. You want to know whether this gives you any evidence against the null hypothesis (and thus, *for* your original supposition that the coin is loaded). Obviously, not every 10 flips of a fair coin will come up with 5 heads, so the fact that you got more heads than tails doesn't necessarily tell you the coin is loaded. A *p-value* - which is what the 'p' in your question is referring to - is the chance of getting the results you got *if the null hypothesis had been true*. In this example, it's the chance of getting 7 heads out of 10 flips if the coin were fair. It turns out it's a little less than 12%, which isn't *that* unlikely, so you don't have very good evidence to say the coin is loaded. On the other hand, the chance of flipping *nine* heads out of ten on a fair coin is less than 1%, so if you'd observed that instead, you'd have very good evidence to disprove your null hypothesis (i.e., evidence against the coin being fair). Lower p-values, which correspond to lower chances of getting your given result if your null hypothesis (remember, this is the opposite of what you're trying to prove) had been true, provide stronger evidence. In academic writing, a p-value of less than 0.05 (that is, less than a 5% chance) is an arbitrary cutoff that is usually seen as the most generous threshold of evidence. Lower p-values, like those less than 1%, less than 0.1%, or even lower than that, provide progressively stronger evidence.

As a developer, what is the biggest challenge you’re facing now? What do you wish you could do better?

gathering requirements, as always. there's nothing i find particularly difficult about coding or designing a system that works if i know what it's supposed to do. it may not be the best but it'll be relatively solid and function as intended. the hard part is putting multiple people in a room with different ideas on what they want and distilling that down into something that meets all of their needs.

ELI5: why do puppies (and some grown dogs)often tilt their heads to the side when spoken to by humans?

Dogs are particularly sensitive to the tiny difference in time between hearing something in each ear, and tilting their head allows them to better identify where a sound is coming from or how far away it is.

What does Foucault mean by 'discourse'?

In short, Foucault's view of discourse mostly centers around the relationship between power and knowledge. His concern wasn't really "what *is* said"/"what is true?" but *"*what *can* we say?" or "which truth is relevant in this context?" Put another way, the question can be phrased as "what is it possible to say/know?" The answer to the question is complicated depending on what system you're working in, but Foucault's central argument is that what's possible to say is constrained by relations of power. Power isn't just held by the "powerful"; the key term here is *relation* of power. Power is not a thing you have, but a relationship structured by history, context, politics, ideas, etc. This is the bit that gets Foucault pegged as a radical social constructionist, imo. Power and knowledge are intertwined with one another - one follows the other. Power relies on knowledge to function; *however*, power also tends to reproduce knowledges that are best suited for its intentions. (Intentions is a bad word, here - this kind of power is not really held by any one person or even an institution, it's far more diffuse than that. But we'll stick with intentions for now). A good example of this playing out in analysis is his text *Birth of the Clinic*. Now, to your specific question: a discourse is a field of various power-knowledges, relations of power, etc that operate via certain exclusions. A discourse is a grouping or network of objects, ideas, places, people, histories that limit *who* can say *what*, *where* they can say it, and *how* they can say it. It's important to understand power and knowledge as distinct concepts so you can understand how they structure various discourses. \#metoo is an interesting, albeit politically complex instantiation of this. The relations of power are changing so that people who formerly *could not speak* \- victims of sexual abuse/harassment - now feel as though they *can* speak. But look at *where* they tend to speak - social media, not the justice system. Relations of power are changing for more visibility, but not in every sphere of modern life. Think about all the things that influence how this works - Twitter comes up with a special emoji for it, we have a hashtag for it, but outside the twitterverse we have significant, oppositional legal and political forces, influencing how the movement understands itself internally. Another example from politics: we have #BlackLivesMatter. This is a statement that emerges for a variety of reasons, with an extensive backstory, but for simplicity's sake let's say it's a response to disproportionate police killings of black men. In response, those opposed to BLM develop statements like All Lives Matter or Blue Lives Matter. A discursive analysis through Foucauldian lens would ask two questions (probably: "How does All Lives Matter *make sense* as a response to BLM, given the history and context of BLM, and how was it *allowed* to make sense as a response in society?" You would have to analyze conservative politics, white supremacy, history, etc to understand how that statement emerged as an intelligible response to BLM. that's a discursive analysis.

ELI5 How Mirrors Work

Your eyes work by noticing light. The sun seems bright because you are noticing a LOT of light from it. Colours are because your eyes can also notice the difference between different kinds of light. A mirror has a special surface that makes light bounce off it, so when you look at a mirror, you're really noticing the light that has hit the mirror and bounced off it. This light has kept the colours and arrangements from what it had before it bounced of the mirror, so what you see is like what you would have seen if you were looking out from the mirror itself.

How does a keygen generator actually come up with a valid registration key?

The CD key must match some pattern in order to be recognized as valid by the application, like "*every odd character must be a letter, while every even character must be a number, e.g. A1B2C3...*" as a very simple example. The keygen produces random keys that follow that pattern, after the developer has managed to find out what the pattern is through reverse engineering of the application.

ELI5 why the light on my Dell AC Adapter doesn't go out immediately after unplugging it.

Sometimes electricity "goes away" the instant I unplug whatever it is that was being powered. Other times, it appears to hang around for a few seconds. For example, when I unplug my television or vacuum, it turns off instantly. When I unplug my dell laptop AC Adapter, yes, the computer stops being powered instantly, but there is still some small amount of power that keeps the light on at the tip of the plug illuminated for about 5 seconds or so. Why?

Let's imagine that you have a small water mill and a glass. If you use the glass directly on the water mill, the water mill will not turn regularly because you need to refill your glass with water. Now, let's use a funnel between your glass and your mill. You are now able to run your mill. (Most of sand mill toys are designed with this funnel!) When you stop filling your funnel, it takes some seconds for the funnel to empty. The glass is more or less your AC power, the funnel is a capacitor, the stream of water is DC power, and the mill is your led.

ELI5: How is a computer programmed to *not* play a game optimally? (Chess, for example)

For reference, on lichess.org, you can play against the machine. You must choose a "level" to play on from 1-8. How is the programming different between each of these levels?

Many programs work by searching through thousands or even millions of possible moves. Not just what move is next, but what will happen after that, and what will happen after that. When you reduce the computer's level, you tell it to examine fewer possible moves, less far into the future, before making its decision.