Split (3)

train · 279k rows

query stringlengths 8 249	answer stringlengths 45 7.8k
How can the furthest edges of the observable universe be 45 billion light years away if the universe is only 13 billion years old?	I believe it has to do with the fact that space is expanding everywhere in the universe. So imagine a beam of light traveling between a star and us here on earth. Since it left its star the space between it and us has continued to expand. So let's say that when the light originally left the star, it only needed to cross 10 billion light years to reach us here on earth. Once it reaches half way though, the space in front of the light has expanded quite a bit. So instead of only needing to cross 5 billion light years, it still needs to cross 7 or 8 billion light years. I don't know the exact calculations, but I believe the general principle is correct.
Why does the U.S. still not use the metric system?	I could write a lengthy reason as to why but I'm feeling lazy so just read [this] It explains everything you need to know", 'This question concerns one of the most frequently asked topics on ELI5, so it has been removed. Try the searchbar next time pleaseWe do. For over a hundred years. Just not in the civilian world. Give it timeIt would be like changing the qwerty keyboard.
What was an average German soldiers mindset pre, during, and post WW2	Let's invade England!" - which turned into pessimism and fear as the war dragged on. By all account, the German soldier was highly motivated yet not a psychotic monster at all. Political indoctrination and racism were kept at arms length due to the officer-corps being composed of old noblemen - these guys wanted little to do with Hitler and his cronies. So, the average Landser was just like any other soldier in any other country's army: a young man stuck in a terrible position. Accounts I 've read speak of Wehrmacht soldiers holding the enemy in high regard - at least on the western front - which might explain why so few atrocities were attributed to the Wehrmacht. In general, you could say that they were mostly OK guys fighting for a terrible regime, so they were more "tragic" than "evil". That having been said, some elite troops were a different matter though. The Waffen-SS was extremely politically and racially motivated. These guys have been responsible for some of the more poignant war crimes commited on both the Eastern and Western fronts. Then there were the Einsatzgruppen: small groups of Wehrmacht soldiers, SS-men, police troops and volunteers who were composed for only one reason: to kill jewish people in conquered territories. These guys were a different breed - one might even go so far as to say they weren't even soldiers to begin with. Then there were some Wehrmacht units that were used to mop up resistance or partizans. Those units soon became disillusioned, turning to booze and becoming increasingly violent as time progressed.
How is Rob Ford still the mayor?	From what I've heard he actually represents his peoples' views very well. It's just what he does when he goes home for the day that gets him in trouble. But he's pretty good at his job when he is at work.And here's yet another joke -- the city elections are this fall and Rob Ford is the favourite to win yet another term. Toronto has had some weird mayors. Though, by being the laughing stock of North America, maybe that could encourage tourism to Toronto. "This is the crack house where the mayor Rob Ford smoked".He has no shame, and thus won't step down.
Why can visible light pass through my window but not through my wall? Why does this restriction not apply to radio and gamma waves?	Excellent question. Another poster explained why glass is transparent. I'll just follow up on that with saying that light is transparent to UV but not to IR. So when sunlight enters a greenhouse, it is reflected from plants in more of the IR range, which gets internally reflected, which is why greenhouses warm up. A good follow-up question is what makes something opaque. Why, for example, does ozone in the atmosphere filter out so much of the UV, when it lets other wavelengths through pretty easily?
Why is fish not considered meat?	what do you do actually?" Drive a bulldozer. "operating engineer" I debug code. "Software engineer" I wax the floors after closing. "custodial engineer". What ever. It's just a word. The real key is, don't answer simple questions with labels. When at a cookout and they ask if you want a burger, just say "No, thank you." Don't say "I am a vegetarian because the meat industry is unethical and is destroying the world with cow fart methane." If they ask if you want cheese on your salad just say "No, thank you." instead of "That is the product of animal slavery and I don't eat it because I am a vegan." If you are lactose intolerant and they ask if you want ice cream with your pie, just say "No, thank you." they don't need a list of symptoms that will occur to you later, and why most of the world can't eat dairy due to lack of the gene that allows proper processing of lactose into adulthood.Every time I tell someone I'm vegetarian they ask about fish. I always have to jokingly remind them that fish aren't swimming vegetables..
What is the difference between legalization and decriminalization of marijuana?	Legaizlation: not a crime to smoke pot. Decriminalization: It's a crime to smoke pot but we won't arrest or prosecute you. We promise. Until someone new is elected or the public opinion on this issue changes. But until then, toke up.
Why doesn't flat seltzer taste like regular water?	It's still got higher CO2 levels than normal water, and it will be more acidic than the same water, flat.actual seltzer is mineral water. it would naturally taste different. carbonated water, which is created artificially, still contains carbonic acid when "flat" because the liquid is still under atmospheric pressure. the carbonate ion happens to taste bitter/sour.
what is dark energy and dark matter?	Dark matter is the name we give to the extra matter in a galaxy that we can't detect. Basically, scientists can measure the weight of a galaxy in many ways. But, if you try to measure it by using the rotation speed and by what you can see, those two numbers don't match up. The mass measured by the light that comes out of a galaxy is too little to hold it together by gravity. So, the dark parts of a galaxy must make up the rest of that weight . Dark energy is something different. The universe is expanding. It is not expanding at a constant rate, nor it is slowing down, which is what would be logically expected. In fact, the expansion is accelerating. Well, something has to be accelerating it, and that something is what scientists call dark energy.
What does the conductor of an orchestra actually do?	Think of a conductor as being sort of a live metronome, sound mixer, and all around sound manager all at once. He or she maintains the rhythm of the orchestra, speeding it up and slowing down as needed. They also indicate to specific sections if they need to be slower, faster, louder, or softer. In practice sessions and in warm-ups before the actual concert, they'll identify parts that may need to be changed or alerted, maybe move one part of the arrangement from one group of instruments to another, make sure no one is out of tune, and just that everyone is on the same page, so to speak.
if European diseases killed 90% of indigenous N & S Americans, why didn't American diseases return the favor when European ships returned?	Actually they did. [Syphilis] is thought to have come from the new world and was untreatable until a cure was found in 1910. Most diseases which cause plague in humans originate in another species and cross over to humans. Given Europeans close contact with domesticated farm animals over thousands of years they built up a genetic immunity or resistance to diseases like smallpox. The Native Americans had only domesticated a few isolated species in the New World and thus had little genetic resistance to these European diseases. This whole subject is discussed at length in Jared Diamond's [Guns Germs and Steel]
Why is it so hard for the top scientists in other countries to figure out how to make nuclear weapons when the process for fission and fusion is so clearly explained all over the internet?	Making weapons grade nuclear fuel is very difficult. More than 99% of naturally occurring uranium is the wrong kind, and there is no chemical process that will separate out the good stuff. You have to boil it into a gas, then spin it around and let the heavy stuff settle in the bottle, in what is called a gas centrifuge. Gas centrifuges are very difficult to make, and most developing countries don't have the ability to produce them. They get most of their technology from other countries, so while they might have the latest civilian technologies, they don't really know how to make new technologies, and their native technology levels can be a century behind the developed world.
Theoretically if we could travel faster than light would we be able to see earth in the past with our naked eyes?	We really don't know. All of our laws regarding physics simply stop at C. None of the formulas work beyond that point. This is a theoretical scenario that we really can't predict the outcome of.Yes. If you were magically to teleport faster than light you can see yourself
Why does the sweat from the armpit smell worse than sweat from any other part of the body?	What you smell is bacteria and mold etc. that thrive in the moist warm area. I heard that some guys from MIT where working on a bacteria that would kill the smelliest and make your armpits smell better. I don't know if they ever succeeded though.Do you routinely smell the sweat in your crotch, your butt crack, and between your toes? Our armpits are just the most ergonomic stinky-sweat spot we can smell ourselves.
Why can people live in Hiroshima & Nagasaki but not in Chernobyl?	The radiation generated in Hiroshima and Nagasaki was created from a nuclear weapon of rather limited payload about seventy years ago. A big part of it was caused by 'neutron bombardment', where neutrons from the explosion hit atoms in materials around them and made them radioactive. There's still some residual radiation but the majority is now gone because those radioactive results have decayed away. Chernobyl is a different matter. It was a radioactive core that went into full meltdown and explosively gave off tremendous amounts of highly radioactive dust and smoke. The amount of source material that was in the core, and added to it the amount of surrounding material like the concrete and reservoirs in the reactor that were affected by the core's energetic bombardment, was hundreds of times more than what was in or created by both nuclear weapons. A huge chunk of highly radioactive dust settled around the plant and poisoned it, and because that type of radioactive material lasts a long time before decaying into non-dangerous other atoms, made it dangerous for many years to come.There's also like a forty-year gap between those events, so there was more time, and also the bombs had a much lower yield. But it wasn't all peaches and cream in Japan afterwards either. In Japan, leukemia was known as the "atom bomb disease" for a long time, because a lot of children in the Hiroshima/Nagasaki area died of leukemia in the 1950s from radiation poisoning.
What's the deal with Bermuda Triangle?	It's another one of those topics that conspiracy-mongers jump on. I did research on it long ago and most of the evidence can be explained logically. Area prone to hurricanes, has a pretty average sink rate compared to similar areas, and ships travel in it all the time.
Why is yawning 'contagious'?	No source, but I recall hearing that it was a sign that the group you were in was safe to sleep around. A person won't catch yawns if they are anxious or expecting trouble . If you are yawning and then everyone else is yawning too, then everyone feels safe enough to sleep and nobody is expecting trouble. If people aren't yawning it means that shit might be about to go down and sleep is a bad idea right now.
Why people are left-handed or right-handed - why don't we learn to be equally skilled with both hands?	Because that's twice the work. Muscle memory is limited to whatever specific muscles you are using at the time. You CAN learn to write, throw, play guitar, etc, with either hand, but it's pretty impractical since you have virtually no chance of losing your dominant hand in your lifetime.
how are the cities of Hiroshima and Nagasaki habitable today, but Chernobyl won't be habitable for another 22,000 years ?	I recommend you to watch Pandora's Promise-documentary. There's actually people living in Chernobyl region.As a Ukrainian I can tell you that there are people living not that far from Chernobyl. Also for around $100 you can go check put Chernobyl itselfThe nuclear meltdown at Chernobyl was that much stronger than the bombs dropped on Hiroshima and NagasakiChernobly will be habitable soon. Animals and plants have already returned', "The explanation for five year olds: A nuclear bomb has kilograms of uranium. A nuclear reactor has tons. Some other sources of radioactivity are generated by both, but the primary one is the leftover halves of an atom once it's been split. Nuclear reactors split a lot more atoms than nuclear bombs, so at the end of the day they have more fission products. Interestingly, a larger nuclear weapon wouldn't increase radioactivity much, since at larger sizes, the fission reaction is just a primer for a fusion reaction. The fusion reaction doesn't produce fallout the way the fission reaction does.
Where do all the bugs go during winter?	this answer will depend on the insect using your mosquito example some species can survive the winter, but will generally not bite below a certain temperature. after the first frost, they enter a hibernation state. other species have larvae that survive winter weather. earth is also a pretty good insulator at a certain depth below the frost layer, the temperature doesn't vary much .you can experience this if you take a tour of a mine shaft at a certain depth below the surface, the temps remain constant in winter or summer so other bugs might be able to survive by digging deeper into the ground.They have antifreeze proteins in their blood! This prevents ice from forming and destroying their cells. Link: _URL_0_', "They die, enter dormancy or just hide where it's still warm.
why aren't we using Thorium nuclear fuel?	A lot of money was invested into uranium and plutonium based nuclear technology during the Cold War, because they could be weaponized easily. Thorium isn't, so less money was put into it.
Why are spaceports/space centers located at sea level rather than at a higher altitude considering the amount of fuel needed just to clear the first few thousand feet of the Earth's atmosphere.	A lot of it is not launching over populated areas. USAF has two space launch sites: Vandenberg in California and Patrick in Florida. Polar launches go South from Vandenberg. Can't go South from Patrick because Brazil. Equatorial launches go East from Patrick. Can't go East from Vandenberg because rest of U.S.
Why do airlines "overbook" flights?	Oh, they are completely aware of the fact that they're selling more ticktes than they have places. But airlines don't expect everyone who bought a ticket to actually get on the plane. For example because people might miss their flights. Airlines have statistics and can judge how many people won't actually claim their seat on any given airplane. However as airplanes don't want to fly with empty seats, they sell more tickets than they have places. Hope this helps!
Why is Genghis Khan remembered as a great hero, or at least conqueror if he murdered 40m+ people?	Hero / Villain is a matter of perspective. You're a hero to the side whose Ideals you're defending. You're a villian to the side that suffers from you defending those ideals. Hitler was a hero to his party for defending their ideals, he was a villain to the rest of the world.Thats why people say you're a hero if you win, if you win your sides' ideals have won over the others.
Why is the Civil War so heavily blamed on slavery, while there were so many other reasons for the war?	There really were only two issues, which were closely interrelated: the issue of a State's right to secede, and the issue of slavery. It is blamed on slavery because slavery was the underlying issue that caused the Southern States to attempt secession in the first place.
Why has the United States never adopted the metric system?	From reading the replies I've come to the conclusion that America doesn't switch over to the metric system because /u/DrMurky doesn't want to.
How does a EMP work?	This is probably a little bit above ELI5 territory, but I'll have a go. Most EMP is a result of a nuclear explosion. What happens is that the reaction releases a lot of radiation that will hit atoms in surrounding matter and strip off the electrons of that matter, turning them in to ions. ions are electrically conductive, so you suddenly have a huge mass of air with free electrons moving around in it. The electrons flow around inside the mass before finally being captured by the ions that they were originally stripped from. This all happens very fast and creates a HUGE magnetic field that forms and dissipates. Electricity moving creates a magnetic field. A magnetic field moving creates electric flow. And conductive materials within range will have electric flow created by the magnetic field. This flow can be strong enough to melt wires, burn out delicate components, etc. There are also machines capable of producing a local EMP effect that are used by defense companies to test electronics to see if they can survive an EMP, but otherwise most EMP are caused by nukes.
During WW1 trench warfare, why couldn't they land artillery shells into the trenches and blow them up?	Shells indeed landed in trenches, but they present a much smaller footprint for a direct concussion wave to work on. Shrapnel weapons at the time were air burst and angled down from their flight path, which meant being dug in and presenting a smaller cross section was also of benifit. It's easier illustrated this way; in an artillery barrage, would you prefer to be standing on flat ground in the middle of the barrage zone or inside a foxhole where you're protected to above head height?
Why is the verb "to be" irregular in almost every language?	come into being". As well as the English "be" and "been", this gave us: * German "ich bin" and "du bist" * Latin perfective tenses, e.g. "fui" * Greek "phu-" * Russian "byt\'" and so on. This is known as the "b-root" of the verb "to be". The other root is the "am/was verb", which comes from a different verb and that verb was itself a conglomerate. The "am" part comes from the "s-root", which goes back to PIE *esmi-. This gives us the English forms "am
What is Heisenberg's uncertainty principle in layman's terms?	You can't know both where something is and how fast it's moving. The more you know about one, the less you can know about the other.
How come photons have no mass (0.000...), don't interact with the higgs field, but are caught by black holes?	Gravity is often called a force, but it's really just acceleration produced by the bending of space. You can tell because a bowling ball and a feather have the same acceleration in a vacuum. A force is only produced if you try to counter the accelerating mass. A hypothetical massless particle would do the same, simply accelerating but taking no force to counter. By the way, photons only have zero _rest_ mass. Momentum adds to the mass of anything that's moving, including photons. This is what 'massless' particles actually do in special relativity. It's how photons contribute to the mass of a black hole.Photons follow a geodesic this is not a straight line when spacetime itself is curved.\xa0 Mass and energy distort the actual geometry of spacetime. This is why photons get sucked into black holesNot an answer, but a question. Is a black hole a sphere?', "As others have said, black holes bend space, imagine drawing a straight line on a piece of plastic, if you bend the plastic the line would curve but it's still a straight line when viewed from the reference frame of the plastic.
Why do boobs in classical artworks look so different from those sported by today's models? [NSFW]	Rubens didn't paint for people to fap, that's the big difference I think.Being able to paint the human body in a lifelike way requires detailed knowledge of human anatomy. Old school painters were generally more interested in the male form than the female form and so while male nudes frequently look really real, titties often times look like overdeveloped pectoral muscles or like bags of sandI dated a girl that had boobies like the Venus of Urbino but a better body. Can confirm is eroticMaja Desnuda, also looks normal to me. Boobies come in all shapes and sizes
Why does my nose run when it is cold outside?	With the weather outside it's probably the tears in my eyes and mucus in my nose melting when I walk into a room that it's experiencing an arctic chill.
How are we able to see so far out into what is the "observable universe?"	Very strong telescopes, and a long time. Light doesn't just die out--as long as it doesn't hit anything and get scattered, light just keeps going. The further you are from something, the more spread out the light gets, so the harder it is to see. But as long as there's some light, it's not impossible. And space is just that--space. There's a lot of matter out there, but most of it is collected in galaxies and stars, so as long as you're not looking right into our own galaxy, you can see light that's traveled for billions of years without hitting anything. Of course, this light is extremely faint, so we need big telescopes to collect as much of it as possible. And to do that, we also take very long exposures. The [Hubble Deep Field] was taken over the course of ten days, with over 300 separate images. This lets us collect enough light to make some of the most distant images we've ever seen.
how can people take pictures of the Milky Way Galaxy. Don't we reside in the Milky Way Galaxy?	Others have already answered correctly that images looking in from outside the Milky Way are either artist impressions or 3d computer models. But I wanted to add a few details on how we produce those 3d models of the Galaxy if we're inside. We basically have to work out exactly how far each star is from earth. There are two methods we use - for things close to us we can look at the angle to the object when the earth is in different positions around the sun Then we use trigonometry to tell us how far away it is. For things further away, errors in measuring angles mean trigonometry gets less and less accurate. So we use star brightness instead. If we know the color of a star, we know how bright it should be at a given distance. We've calibrated this using all the stars that are nearby, where the first method still works. Knowing how far away each star is lets us build up a 3d model, and then we can essentially move around and take computer generated images of the galaxy from any perspective we like.
why, does water expand when if freezes?	BTW, if it didn't expand we'd be hosed. The icebergs and glaciers at the poles would sink to the bottom of the oceans and eventually all the oceans would be frozen as more and more surface ice stacked up. We are very lucky that water is one of the only liquids that expands when it freezes.
If we have telescopes that can see galaxies light years away, what's the reason we focus them on nearby planets to take a look at their surfaces?	I think you forgot a 'don't in your question. I have no idea what the answer is, I'm guessing it has to do with resolution. I have wondered a similar thing about pointing telescopes/cameras at the moon and taking pictures of the equipment left behind after the lunar landings, just to shut up the conspiracy goobers that say it was a hoax.
Different breeds of the same species of animals have different natural tendencies, characteristics and behaviors, so why don't humans of different races vary in the same ways?	Asian" is very much not founded on biology. Also, the idea that Genetics cannot influence Human behavior based on "Race" is a complicated one. In part, it is due to the fact that the "Races" are too inaccurate to describe genetic heritage and therefore infer behavior. Another part is due to the fact that humans are a lot more capable of breaking their natural instincts than dogs can, so are a lot less affected by genetics. And another part is due to the fact that environmental conditions such as upbringings, culture, etc play a huge role on human behavior, which can easily mask whatever role genetics play. And finally, a part of it is due to political correctness, a political move to try to hide genetic differences between people to mitigate racism. An example of such PC move is a study in the University of Chicago that found evidence linking Intelligence and a specific gene. But the study was shut down after the discovery that the said gene was more common in European ethnicities than Africans. The lead researcher was quoted in saying "Some knowledge just isn't worth having".The differences which lead to what we call different races are very minor, and pretty much arbitrary. Not a lot about our genes are different to get from pale skin, to dark skin. In fact, two people of the same race can be more diverse genetically, than two people of differing races. In essence, we've defined race by some characteristics that we choose to consider important , but which otherwise aren't particularly impactful, compared to something like how we define breeds in dogs.
Why will we never be able to travel the speed of light?	You might be interested in something called the Alcubierre drive. It wouldn't go faster than light but it would shrink the distance you have to travel basically.
If a golf ball has dimples that decrease the drag and make it fly further, then why is that same concept not applied to race cars or airplanes?	A TV show where 2 guys did experiments based on myths used body puddy to make dimples in a car. Added a lot of extra weight and to everyone's surprize, the car's gas mileage was about 9mpg better. ", 'Side Comment: I remember reading somewhere that someone dimpled a baseball bat and the MLB ended up banning dimpled bats because of the advantage they gave.
Is light a wave or a particle and which one do we 'see'?	It is both. It acts like a particle, but those particles spread out in waves. In quantum mechanics, you can't tell where a particle is going to be, you can say that there is a 12% chance it will be here, 20% it's going to be here, and so on. This probability spreads out like a wave.
Why doesn't the U.S. adopt the metric system?	Actually, we almost did change in the early 1970's. All the legislation was passed, a changeover date selected, etc. but a bunch of know-nothings started writing editorials and letters to editors that they would have to re-calculate all the measurements for grandma's cinnamon rolls each time they made them, look up a celsius to fahrenheit chart to find out what the REAL temperature was and multiply the speed limit signs by .62 to find out how fast they were going. We were only weeks or a few months away from the changeover when fear won out over reason.
Why do people have Deja vu for things that clearly never happened? In other words, what happens in your brain when you experience deja vu?	I once had deja vu that was insanely real. I used to have this reoccuring dream that I would look down on a picture that rested on a counter in a place I wasn't familiar with. One day I was in a home ec class in high school and it happened. That same set-up, same place, same everything; I walked up to a picture on the counter that someone wanted me to see, and it hit me, that was what I had seen multiple times. In my dream, however, the picture was always blurry.
When we use antibacterial soap that kills 99.99% of bacteria, are we not just selecting only the strongest and most resistant bacteria to repopulate our hands?	And not building our immune systems? Why yes, OP, you are correct. They've done studies that show that children that pick and eat their boogers have the strongest immune systems later in life. Go finger
dinosaurs existed on earth for many millions of years longer than we have. Why did they never produce an intelligent species like us?	Because evolution doesn't have goals and isn't trying to make intelligence or anything else. It's only finding good-enough, not perfect. And until a massive event wiped them out, dinosaurs were doing fine. And anyway, there are downsides to high intelligence - big brains take big energy to feed them, which drives up caloric requirements and makes it harder for animals to survive.
If we can clone animals, why is there a danger that many species might go extinct?	Cloning doesn't quite work like that. You can replicate an animal's genetics into an embryo, but you still need a parent of the same species to carry and birth it. There's also the issue of genetic diversity increasing the survivability of a species, and individual clones being expensive.
Why do some planes leave vapor-trails (contrails) while other planes flying at the same time do not?	The amount of humidity in the air. When it's humid and the water wants to form clouds, but it needs dust to stick to. The spent fumes from the exhaust of the jets contains enough particles for the water to stick to. This makes a streak of clouds behind the plane. This is what I remember from a book I read twenty years ago. I'm sure someone can explain it better.
why does only one nostril get blocked when you have a stuffy nose?	The construction of individual nostrils is a well understood follower of circadian rhythms. Keep a chart and you'll see that for most people it's even the same nostril open at the same times of day. The more constricted at a given time is more likely to become easily plugged.
The Deep Web & The Dark Web	I can only answer #3 from the Top of my head. I could be wrong So I'm regular user for a browser called Tor. This is the door to the Dark web . You can get Tor 100% for free. The Tor browser is used for anonymity on the internet, but due to this a lot of illegal stuff can be found. Drug markets Hitman . Child pornography Stolen credit cards. You name it. There are some regular sites though like journalism or free books. If yiu go on youtube Alltime10s has a video on the subject. And there are plenty of sub reddits here for the topic . Also i belive tor works like this: your ip address is sent to different relay computers from around the world each changing your location. This makes it harder to find the user and etc. #1 choice for illegal stuff ;) *Note i'm fairly new to reddit so sorry for any formatting errors. oh and ive seen some weird stuff on there Some stuff can get you in big trouble. Never download anything from there. Advice from a 15 year old.
why didn't the spanish die of native american diseases but the other way around?	Because they had more contact with other far off places before they got to the New World. They also suffered diseases like the Bubonic Plague that came from those contacts, so it isn't like they were totally immune, but that constant exposure made them more immune. Though Tobacco & Syphilis are New World items, so maybe the Native Americans got the last laugh after all.I'm part way through the more than a little cumbersome book "Guns, Germs, and Steel." It seems that the "germs" part is attributed to population density and the practice of keeping domestic animals. I'm not saying it is right, I'm just saying a book offers that explanation.
Why does inbreeding so often cause birth defects?	look at eye color. lets say blue eyes are undesirable. your grandma has blue eyes. your mother has brown eyes. your grandmother is necessarily bb and your mother necessarily Bb, a carrier for blue. she hides her mothers affliction to find a mate, and marries a a brown eyed gentlman with no such familial defect. they cannot have a blue eyed child, but there is a 50 percent chance that each child is a carrier. if you were to mate with an unrelated brown eyed person, they would be less likely to be carriers than you. blue eyes are fairly rare. hell, you may not have the gene . given the odds, it would be less likely for the two of you to have a blue eyed child than if you were going to mate with your sibling , or worse, your mothers sibling, who is DEFINITELY a carrier. now lets say you do have the blue gene, but your sibling does not and you have children. again, your children have a 50 percent chance of being carriers. say this goes on for so long, getting lucky with inbreeding, that you forget you guys carry the gene at all. one day somebody is almost certain to have a blue eyed baby because you didn't diversify. two Brown eyed people who carry the blue gene have a 1/4 chance of having a blue eyed baby. and every child born in your family has a 50/50 chance at being a carrier. eventually two carriers will mate and the mistake will happen. and it will always happen, eventually. if it turns out you have a generation where most are carriers, just by chance, and they all breed with each other, several of those children are going to have blue eyes. some will still look normal, some will be normal, but they will have a higher capacity than a more diversified gene pool to have children with blue eyes.
Why do objects with the same mass but different volumes have different gravitational forces?	Gravitational force between two objects is directly determined by the distance between the two objects' centres. The greater the distance, the less the gravity. Compare when you're standing on a planet with the mass of the Earth that's made of solid iron versus a planet that's the same mass as the Earth but made of styrofoam . The first case sees you not that far from the planet's core because the planet is so dense, so your weight will be high. The second sees you're much further away, maybe four times as far from the planet's centre, so your weight will be lower because that much extra distance really reduces the gravitic attraction.
Why is Mars so cold when its atmosphere is almost completely CO2, the greenhouse gas that is warming our planet	Well to start off with Mars has a very thin atmosphere. It is less than 1% of the thickness that exists on the Earth. To make matters worse Mars is about 1.5 times as far away from the Sun as the Earth is meaning that due to the [inverse square law] they only get about 45% of the sunlight that Earth does per square meter. It also lacks a global system of heat distribution like exists on earth in the form of winds and ocean currents . This makes it so the poles are super cold but the equator is around 20º C . The planet as a whole is also about half the size that Earth is so it doesn't have as much area to capture heat to begin with anyways. A better example of a runaway greenhouse effect from CO2 is Venus. It has a very thick atmosphere and is closer to the sun and has an average temperature of 462º C.
The financial crisis in Greece	FWIW, the top comments here are currently not actual ELI5's of the situation. So far they're just biased interpretations of the situation, i.e. the Greece governments interpretation vs. the EU/troikas interpretation. Hopefully someone can present a truly balanced ELI5.
How do hackers hack?	The basic process is: 1) Find a bug in a program 2) Exploit that bug to make the program do something it isn't supposed to. There are a huge number of potentially exploitable bugs, so it's really impossible to go into any more detail without picking a specific class of exploit to talk about. Somebody else has already covered SQL injection, which is a very common bug in web applications. There are other types of code injection exploit , but they're all pretty similar, so I'll provide a description of a stack based buffer overrun, which is another common exploit most frequently found in applications written in C/C++. A buffer overflow occurs when the program writes more bytes into memory than it has allocated. For example, if the program allocates 20 bytes to store the user's input, and the user then inputs 20 bytes, the program ought to check the number of bytes entered and see that it's too long - if this isn't done, there is a potential buffer overflow. When the program writes past the end of the allocated buffer, it will be writing into memory that is being used to store other things, thus allowing the user to alter those values. For a buffer allocated on the stack, one very important value that will always be stored shortly after it is the return address for the function. This tells the program where to return control to when the program has finished executing. Through a specially crafted string, an attacker can overflow the buffer and overwrite the return address to point to their own code. When the function returns, control is then transferred to the attacker's code. Typically that code then spawns a shell, giving the attacker control over the target computer. For this reason, the exploit payload is often referred to as shellcode. An example of a buffer overrun exploit is the [Slammer worm], which exploited a buffer overflow in Microsoft SQL Server to copy itself to thousands of servers in a matter of hours.
Why do microwave waves disrupt WiFi ones? Are they similar enough to interfere with each other? And are there any other types of wave that interfere with each other?	The reason they interfere, is that both of the signals are running on the same spectrum: 2.4GHz. Therefore, when both are transmitting and receiving signals they will of course interfere. Most likely, the microwave will disrupt the WiFi more than the WiFi will disrupt the microwave. But, in an attempt to solve this issue, a 5 GHz WiFi has been developed. In addition, it's much faster than previous generations. Also, another way to avoid interference, is to use a wired connection, whether it's direct to the router or power line adapters.
Why are we searching so hard for water on other planets? Can't life exist without water?	Life on earth developed as we know it because at some point living cells in the water on this planet started doing photosynthesis and converted water into oxygen . Thats more or less how the atmosphere came to be. Almost every kind of life on earth needs water and oxygen to exist, water is the medium from which life resulted and oxygen the fuel to lots of cells for producing energy. That's why we look for planets containing water. All the others are too different compared to our planet and our understanding of biology.
What actually happens when you crack knuckles and other joints.	The pop you hear when you crack your knuckles, is the liquid in your joints changing it's state to gas form because of the low pressure.
what makes yawning contagious?	Same thing that makes you cringe when you see someone else get hurt, or laugh when others are laughing. We're wired to empathize with each other, and to some degree feel what those around is feel. I believe mirror neurons is a relevant term worth looking up. Maybe someone not on mobile can fill in.
If hot air rises, why is it colder at higher altitudes? At what point (altitude) does the temperature getting colder at higher altitudes outweigh the fact that hot air rises?	The air cools as it rises. Dry air would cool at 3 degrees celsius/1000' altitude change, saturated air would cool at 1.5 degrees celsius/1000'. So basically temperature, pressure, and volume are related. Think of a piston in a diesel engine, during the compression stroke the amount of air shrinks, the pressure increases, and the temperature increases until the diesel burns Same idea. So as the parcel of air rises, there's less atmospheric pressure acting on it, and it expands, and cools because of that expansion. To answer the second part of your question, the point that the change would happen would depend on the temperature difference between a parcel of rising air and the air around it.
If plane wings are designed create lift in one direction, why doesn't a plane flying upside down plummet to the ground?	Stunt plane wings aren't designed to create lift in one direction. They're actually symmetrical top to bottom. Instead they rely on angle of attack to generate lift.
If two rockets move away from each other at 0.75 the speed of light, would each appear to be going faster than the speed of light from the other rocket?	Pretty sure this will have been answered much better elsewhere, but the basic idea is this : The speed of light is not really just a speed quotient. It represents a limit of space-time. In your example, imagine you're on one of those rockets. Since you're a travelling at a significant portion of the speed of light, you actually experience time at a different rate to others. The other ship is travelling through time much slower, while for you time still moves at what feels like a normal speed. An observer on the ground , would see each ship moving extremely fast, away from each other. If the ships were travelling directly away from the person on the ground, the light from their engines would reach them, but would be experienced very differently since its position is changing so quickly relative to how it is observed. I'm sure I've missed most of the nuance, but at relative speeds, things change drastically depending on the observer. If you want to experience this, have a go of this free game from the boffins at MIT. It's mind blowing. _URL_0_ Edit: a words.If Alice and Bob are zooming away from earth in opposite directions at speeds Valice and Vbob, then the speed Alice sees Bob zoom away at is not simply Valice + Vbob. It's actually: Vcombined = Valice + Lfactor * Vbob What is the Lfactor? And why don't we notice this normally? Lfactor is the "Lorenz factor" _URL_1_ and it's a number which is always a bit less than 1, but unless the speeds you're dealing with a significant proportion of the speed of light, it's so close to 1 that we don't notice the difference - so we "grew up" thinking you just need to add the speeds. And the way the Lfactor works is that no matter what Valice and Vbob are, adding them together will never get you a Vcombined bigger than the speed of light.
Why don't electrons stick to the nucleus?	Have you ever had really evasive piece of seafood or mushroom on your plate? You seem to pin it down, but it gets away every time. However, from general perspective, it's located on your plate and is not going anywhere. Well, particles have this sort of thing around them, their personal space. You can say that they are in this space, but try to pin them more accurately and they get really evasive. In fact, they not only have room in space, but in available momentums too. Imagine that you have some 2 m of guaranteed personal space on X axis and on Z axis which both go horizontally and also 3 m on Y axis which goes vertically. You'll have 2x2x3=12m^3 of personal space. If you also have 5$ of available money then you may say that you have 5x12=60$m^3 of personal space. Personal space of particles is described by momentum * coordinate and is strictly guaranteed to be no lower than a certain number, ever. This number is very low - that 12m^3 of space on a scale of Solar system wouldn't be even close - so from our, huge-world perspective, particles can be pinned down pretty accurately until certain limits and then things just get weird. If you push a particle into really tight space it gains huge freedom of momentum and will be gone pretty soon. You can operate with particle in our classic approaches as long as you leave it enough personal space, but try to get closer than that and you'll never know certainly where the particle will turn out to be. If electron was to stick to nucleus it would violate its personal freedom space, so that'll never happen. Works for other things too, but the more mass they have, the less their momentum freedom means because it fails to grant any noticeable speed difference.
What it would take for me to remain still while everything around me continues to spin with the planets rotation.	You could theoretically set up equipment on one of the poles to simulate this. Basically, you would design it up to rotate you counter to the earth's spin.
Why we have different blood types?	It has to do with what [type of antigens you have]. Someone who is AB+ has more antigens. To survive against little attackers it is helpful to have these, but why would you have a defense against something you have never had to deal with? If you don't have to deal with B attacker as much, you might no need that B, so nature in your area wouldn't care if you were AB+ or A+, you'd both make it though selection. This is why you see [groupings of blood types]. Notice that populations with higher Native American ancestry have fewer antigen types. There was much less passing of nasties from culture to culture until recently-revolutionary speaking-so they didn't need these. Now, look at Europe spreading that A around and how centralized B is. Edit: Forgot to add a link and a typo.Do we know that we have discovered all blood types or are there some rare varieties out there?
Answer an ELI5 FAQ - Why do planets, asteroids, rings, and other astronomical objects orbit, aligned, in the same plane?	One thing to note in all of this is that most asteroids and other things do not have orbits in the same plane as the other planets. There is an eccentricity to their orbits in both shape and angle. This [photo] shows how out-of-plane Pluto's orbit is. While these objects tend to settle into the same plane, it is not a hard and fast rule that one can apply universally. Quick edit for more examples: [Comet 2008 KV42] [Halley's Comet] [Asteroid 2004 BL86] These are just a few examples. There are millions of out-of-plane objects in our solar system alone.
What do the scientists mean when they say the universe is flat?	They mean that you can't travel so far in one direction that you end up back where you started, as is the case with traversing the globe. Also, right-angled triangles continue to obey Pythagoras even at a large scale, which again is not the case with the Earth. If you make a triangle with one corner at the pole and the other two on the equator, the corners won't add up to 180.
Why does the human body eat muscle before fat when it's in starvation mode?	I really thought it was the other way around. I'm pretty sure your body eats fat first, doesn't it? Otherwise why do bodybuilders still have a shitload of muscle after their cutting phase?
Why and how would a 1100 decibel sound make a black hole larger than the observable universe?	Decibels are a logarithmic scale. Logarithmic scales go up on orders of 10 instead of orders of 1. This means that going from 10 decibels to 30 doesn't mean that you're getting 3 times louder. It means that you're getting 100 times louder. As such, a 1100 decibel sound is close to 100^100 times louder than a 90 decibel sound . Sounds are essentially compressed air. Things vibrate which cause air in the vicinity to compress into waves and travel outward. A 1100 decibel sound would require so much air/matter and the compression would be so intense that all that mass would be compressed into a super massive black hole.So the decibel scale is logarithmic. 10 decibels is 10 times louder than 0. 20 is 100 times louder than 0. 30 decibels is is 1000 time louder than 0. A sound of 1100 decibels would be 10^110 times louder than a 0 decibel sound. That is a ridiculously huge number. If the amount of energy necessary to create a sound that loud were all in one are in space and time, general relativity dictates it would form a black hole. 4 × 10^69 J is the estimated energy density of the observable universe The amount of energy required to create this sound would be even higherBecause decibels is a logarithmic scale. 100 decibels is a loud noise. 1100 db is 10^99 times more powerful than a loud noise. Even at E=mc^2, you would need so much mass to create that much energy that the gravitational pull of that mass would be a black hole capable of devouring the universeThe decibel scale is a logarithmic scale. That means that increasing the amount of decibels by 10 increases the sound intensity by an order of magnitude. . When you input huge decibel levels, you receive ridiculous energies, and hence, massive black holes.
Why does squinting improve vision?	[Like this.] The cons of this is that everything becomes darker . That's why we chose to use 'lens' glasses as opposed to pinhole 'glasses'.This short [video] seems to do a good job of explaining why.
with the massive amount of gravity that the Suns has, why do the planets orbit the sun instead of being drawn into it?	They are being drawn into it, that's why they stay in orbit instead of flying away in a straight line. The gravitational tug of the Sun curves their path.
what is a 401(k)	It's a benefit to employees, like a bonus or healthcare. It's meant to attract better employees. It's basically a retirement savings account with extra benefits: If you deposit money in to it, your company will also deposit money in to it for you. Literally free money. Additionally, as long as you don't touch any of the money until you retire, you can skip paying any taxes on that money until you're retired. That doesn't sound that great on the outside, but it means you can use all the money you didn't pay as taxes and re-invest it over time and earn more. It ends up, after 40 years of investing, turning in to a really big extra chunk of money.
How is it that, according to special relativity, light always appears to move at the same speed, regardless of the speed of the observer?	It is taken as a postulate . It is one of the two postulates from which special relativity is formulated. But it's not just an arbitrary guess, it was motivated by Maxwell's equations. Maxwell's equations are the equations governing classical electric and magnetic fields. Maxwell's equations say that electromagnetic waves should move at the same speed regardless of reference frame. Einstein assumed that was true and derived special relativity.Light moves the same speed through a vacuum. When it goes through atmosphere or materials it does slow down. _URL_4_ And as for in a vacuum. Every test we have ever done has confirmed. We have also confirmed time dilation. _URL_3_
In days of American slavery, were Africans the only people who were forced into slavery, or were there other races as well? Why were some groups forced into slavery while others immune?	Systemic trade by companies that established a source of slaves were able to procure, distribute, and trade/sell Africans. Trade routes along African coast was already established. War slavery was normal in Africa still . Trading companies had wealth and capital. America had an industry that needed lots of cheap manual farm labor. Other groups didn't have the means to be sold into slavery en masse.Native Americans were enslaved. Though it was harder because they were able to run away more easily because they knew the landscape.
Escape velocity. Can't you escape earth's gravity at any speed as long as you had the power?	If you mean to ask if you can escape the Earth's gravity given constant propulsion, then it depends. As long as you're providing more force away from the planet than the pull of gravity at every point, then the answer is yes. You're still going to need a change in velocity of 11.2 km/s no matter what, though.
Why are there more right handed people than left handed people?	They're not just left-handed, there's also apparently a number of other slight differences in psyche and biology. One of theories is that many of them died out because of higher sensitivity to poisons. But nobody knows for sure because according to studies of hand-prints on cave walls even in stone age lefties were already a minority.
what would happen if all the other stars in the universe disapeered? Do they have any effect on the Earth?	I assume you're asking whether the gravitational effect of other stars would affect our own. The simple answer is that they're so far away that the force of gravity from even the closest star has an affect of just about an acceleration of 2*10^-13 m/s^2 on the sun.
Why do humans smell with with a long slow sniff, while most animals rapidly sniff several times.	this is a weird one. But it's a learned thing. there has been some research in scent tracking with humans. in the process of learning this people switched to fast sniffs. long and slow is good for breathing, short and fast is for getting as much of the scent through your nose as you can. tl;dr people are idiots and can also smell rapidly, which is better for smelling and locating a scent
If light cannot escape a black hole, doesn't it mean light is accelerated to faster than the speed of light inside the black hole?	No, inside a black hole all paths lead to the singularity at the center No matter which direction you go, you're headed inward", 'If it were capable of accelerating inside the black hole to speeds that were FTL, then it would be able to achieve an escape velocity.What's your reasoning? It seems likely to me that light, following ridiculously curved space-time, pretty much goes in circles. Why does it have to go faster?", 'I recommend anybody seriously interested in this to look up the PBS Spacetime video series on General Relativity on Youtube. The short of it is that while the explanation that "escape velocity in a black hole is greater than the speed of light" is an intuitive explanation in a Newtonian sense, it's not actually correct, or representative of the actual physics going on.I've been asking this question for the last 3 goddamn years in askscience and everytime it gets downvoted to oblivion right out of the gate. You fucking people.
When you have a cold, why does your nose clear up while you're sleeping, and immediately start running again when you wake up?	My nose blocks up quite quick, and is not quite so bad in the morning, but that's because it's now all in my throat. Tasty.
Why can't we tickle ourselves	Well technically you can but you are expecting that ticklish feeling to come so you're mind is prepared for it, however if someone else does it, you cannot anticipate where or how they will tickle you, hope this answers your question :)
What happens when a lung collapses.	I can answer this from a patient's perspective. I had a [Thoracotomy] to repair a crushed vertebra that resulted from a parachute accident. The chest tube that was inserted post surgery became clogged and my left lung slowly collapsed under the flow of the fluid that was accumulating in my chest. When the doctors realized what was going on, a new tube was inserted and the suction was turned back on. Imagine a balloon blowing up in your chest cavity that suddenly allowed you to draw breath again. Also, you could hear it inflate. It was awesome and gross.
People can't hear their own voice the same way others hear it. So, how is anyone able to do good and accurate impressions of someone else?	Hold your hands in front of your ears and you can hear your voice the same way that other people hear it, I'm sure they just do that while practicing impressions but I could be wrong. Hope this helps! [pretty much exactly like this except you can just use your hands :)]
Dark matter is constantly expanding faster and faster, what happens when it hits light speed?	It's not matter that is expending, it's space itself, thus, a given region of space can grow faster than light, without violating any law.
Why does the axis of the earth have a bigger role in its weather than the distance from the sun?	[This page] has an image that summarizing the effect very succinctly; basically, the greater off of 90 degrees the angle between the sun and the earth's surface is, the more atmosphere the sun's energy has to travel through and the larger the surface area it's spread over.The distance from the sun varies by only a couple of percent, while the angle of your part of the sun varies wildly between summer and winter.
Why is CGI so expensive?	CGI is expensive, because it requires a lot of time, expensive computers, and skilled people to operate them. Remember, the general goal of CGI is to not look like CGI, but to look 'real.' Making something fake look real is difficult. It's easy to get 80% of the way there--but 80%, 90%, even 98% is not going to be unacceptable, especially if it's of a person. We as people are very good at telling that a person is not real, and a fake looking person is rarely received well--it's called the [Uncanny Valley]. The more CGI in a movie, the more of all that you need, so it costs more.
What is the difference between petrol and diesel?	Both diesel and petrol consist primarily of chains of carbon atoms, with all the empty spots filled with hydrogen. The longer chains become diesel, the shorter chains become petrol . Now, the shorter the chain, the easier the fuel ignites. This has effects on how the engine is build. A petrol engine will compress fuel, and then ignite it with an electric discharge from a spark plug. A diesel engine will compress until the fuel explodes on it's own. The fact that diesel compresses the fuel more results in a more efficient engine, but also has it's environmental drawbacks . Now, this difference in engine construction also results in the fact that Diesel engines are used for heavy vehicles. The specific design results in high torque even at low engine speeds.The main difference between petrol and diesel is how it is refined from crude oil. Petrol and diesel are two different hydrocarbons, i.e. two substances made from different amount of hydrogen and carbon.
How do we know that gravity curves spacetime and is not a force?	The difference between gravity and EM is the the force is proportional to the mass rather than the charge. The fact that it is linear is a huge tell tale sign to its nature because the acceleration due to gravity is, therefore, independent of the mass. This leads to the equivalence principle: if you were in a system falling under a uniform gravitational field, there would be no local experiment that you could do to prove that you were accelerating because everything would be accelerating at exactly the same rate. This is unique to the gravitational force. It is this principle that leads to the idea that the cause of the acceleration is a property of space itself. Of course, there's a bit more to it but that's the first thing you learn about when you're starting on general relativity.
Why do humans need to learn how to swim while many other mammals seem to instinctively know how?	Compared to most animals, humans develop extremely slowly and are born very early in their development. The benefit of this is that we have much more potential--the learning we can achieve in our childhood is incredibly much more than any animal, and in large part this is because the young brain is highly adaptable. Were we born more developed, we wouldn't be able to take advantage of that. This evolutionary path is made possible because humans live in groups that can protect the young, where more solitary animals benefit from being able to go it alone early on. Thus, human children have only the most basic survival instincts such as holding their breath underwater or flailing about, and take a year to even walk, but can grow up to be superior to animals that are good swimmers or walkers in mere hours.
Why does hot water taste so different to cold water?	Iron bacteria and minerals accumulate in your water heater. That's part of the reason you are told to use cold water for cooking. Always use the cold water for drinking, and contact your water provider to take a free sample and give you a report on its contents. They should be very helpful.
Why does salt make ice so much colder	It doesn't. It makes an ice-water bath colder. Normally water and ice reach an equilibrium at 0 C or 32 F. At that temperature both ice and liquid water can exist perfectly fine, both can be at the same temperature. If you take energy out of the ice water bath you make more ice, if you put energy in you make more water, but they're in balance. Now if you put salt into the water, it depresses the freezing point. This is because in order to become a solid crystal the molecules have to fit together in a repeatable orderly pattern and introducing other things in, like salt ions, means you have to adjust the ideal pattern to fit. So they can't solidify as easily. So you bring the salt water to equilibrium with the ice at a lower temperature. If you have normal cold ice, then the part in contact with you melts and turns into water. If you have salted cold ice, then the part in contact with you melts and turns into very cold brine.
Why does water put out fire if...	Because of they way they are put together. Water has unique properties that allow it to both take away the heat and oxygen supply of the fire. Oxygen bound to hydrogen is not accessible as a fuel source. Combining elements gives them new properties that the single elements don't have
Why are different races still the same species of human?	Simply put, because race is a social construct and species is a biological construct; the two aren't really related. Humans are all the same species, period. It's important to understand that racial differences are very, very superficial.
Why is there only one species of humans?	There's an idea in studying animals called the competitive exclusion principle. I know that's a lot of words. But what it means is that because humans fought for the same food and living space as other human-like groups who tried to survive in the same space, humans were better at it. This means that humans got the food in an area and were better at driving out animals that wanted that food. This is also the reason there used to be many large mammals predators and there aren't anymore. Competitive Exclusion.The simple answer would be that our lifespan is too long and reproductive rate too slow. Also we have been too interconnected over the past hundred thousand years for our species to diverge into different species.
How do we relate time to the age of certain planets and the entire universe when the speed of "time" varies based on gravity?	I've thought about what you're asking quite a bit; and I think the answer is something along the lines of we're not physicists so we don't really understand the scale of what we're asking. Say you've got Jupiter, it is far more massive than the Earth so time should pass slower there. The Sun is even more massive, and then you have even larger bodies out there shouldn't time be slower around all of them? I think the answer is that, yes it is actually slower, but at scales humans use this slowness is negligible. It only becomes meaningful at theoretical scopes; black holes, neutron stars, etc All that said, there are probably some real-world brain breaking conclusions that could be drawn from this; but I don't have any of the maths to help find them.If we measure time in entropy then are larger mass objects younger than smaller mass objects?
How does a bank work?	A typical local bank does two things, in general. Takes deposits, and loans money. Deposits! This is money you have in your savings account. You give money to the bank, and they will give you some interest. This is because they need your money. What do they need your money for? To make loans Loans! Banks are in the business of loaning money to people. This is how a bank makes money, on the loan interest payments. That's the really basic way banks work. Money comes in from deposits, is loaned out to borrowers, and the bank makes the difference between interest charged and interest paid.You give the bank money - this is effectively a loan. The bank then pays you interest on that loan. That money comes from the bank. Of course, the bank is also taking that money and lending it out to other people at higher rates so really they are paying you a tiny fraction of what your money is worth but hey they gotta make money too right?Per rule 7, please remember to search ELI5 before posting. [Like this.]
If microwaves work by heating water molecules, how do they heat things without water molecules, like plates?	Beyond what's already been said, conduction. You heat the molecules that absorb microwaves, and these molecules then transfer heat to the molecules that don't absorb microwaves around them. Which is one of the main reasons why you should heat frozen things slowly in the microwave. Ice doesn't absorb microwaves significantly, but liquid water does, so if you heat a frozen dinner too quickly you can get a meal that is ridiculously hot in one section and frozen in another.
If a brain transplant was successful, wouldn't you be saving the donor and not the recipient, because you are literally your brain?	Is it really a stupid question? [Let's find out.] For science.In case anyone wants to read about a case: _URL_7_Is a brain transplant not actually a body transplant?
Is there any proof that we can't go faster than light? I mean we couldn't have the technology to do it, but theoretically why is it so impossible to ever do?	When we talk about speed, we normally talk about the rate at which we cover distance, which is distance divided by the time it takes to cover it. What Einstein discovered in his theory of relativity was that we do not just move in space. We also travel forwards through time, from one moment to the next. This might sound obvious, but the weird trick about relativity is that these speeds are actually connected. We always move through space-time at the speed of light . If we are sitting still in space, we are moving at the speed of light through time, and if we are moving at the speed of light through space, we are sitting still in time. The actual math behind this is complicated and really changed the way that we looked at the world, but what's important is that this law doesn't make any sense if things travel faster than the speed of light - if we have something like that and try to figure out the speed it moves through time, we end up taking the square root of a negative number and getting an imaginary result. EDIT: for clarity.
Why didn't American settlers enslave the Native Americans instead of killing them and importing African Slaves?	I've also read lots of slaves returned to Africa, guess what happened to many when they returned? Yep, they were turned into slaves by natives", 'The short answer, as touched on by many people: they tried and failed. Native Americans knew their land, and were being held prisoner in it.Because it's much more difficult to enslave an entire population than buying existing slaves

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.