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Physics is fascinating, but not remotely as mysterious as the popular science media makes it sound. Today, I want to debunk the 10 biggest physics myths because I hope that I won't have to repeat this until the end of my life. Starting with 10. Quantum particles can be in two places at once. This statement is both correct and isn't. It's a weird verbal expression of a mathematical expression. The mathematical expression is that the particles described by a wave function which is a sum of two places. That's what we call a superposition. Yes, a superposition is just a sum. But what does it mean for something to be in one place plus another place. I have no idea. Actually, I think no one has any idea what it means. But because we need to talk about it somehow, we say the particles in two places at once. Is that what the particle really does. Who knows what even is real. Nine. Entropies disorder. I know I've said this myself. It's because the statement makes sense if you have a careful definition of disorder. But in all fairness, it's not what we normally mean by disorder, which is why the statement is confusing. Let me give you an example. Suppose I drip dye into water. The dye will distribute almost evenly. Why. Because this almost perfectly even distribution is the state of maximum entropy. It's the most likely thing to happen. Whereas it's very unlikely that the die goes back into a drop. However, if you look in the early universe, you have an almost perfectly even distribution of matter and that has a very small entropy. Why is that. It's because in this case, the density of the matter is very high. So, you need to take into account the gravitational pull. The gravitational pull wants to clump the matter. It's therefore very unlikely that it's evenly distributed. So, the entropy is small. Now, I'm not sure whether you want to call an even distribution ordered or disordered. I think a case could be made for either, but regardless of which side you fall on, for one of those examples, entropy will not be described by disorder. Eight. Black holes suck in matter. A black hole has exactly the same gravitational pole as a star of the same mass at the same distance. The difference is that since a black hole has a much smaller radius than a star of the same mass, you can get closer to a black hole than you can get to the surface of a star. This means that the gravitational pull at the horizon of a black hole is stronger than at the surface of a star with the same mass. But the gravitational pull of any matter is set by the strength of gravity, which is a constant of nature. It's not like black holes attract matter more strongly than anything else. Are they any more dangerous. Well, if you've fallen to a star, that also kills you. Seven, we all move at the speed of light. This isn't so much wrong as just a meaningless statement. It's a weird way to say that if you look at our motion in space time rather than space, that's by convention normalized to the speed of light. What does that mean. That we move at the speed of light through spaceime per time. For all I can tell, it means nothing. You move through time at 1 second per second. And that's that. Six. The cosmological constant was the worst prediction ever. Wrong by 120 orders of magnitude. This is a catchy story that people keep repeating. Unfortunately, it's not true. There's never been such a prediction. What physicists actually mean when they talk about this is that they have a way to estimate what they think the cosmological constant should be. And that estimate is crudely wrong. What you can conclude from this is that their way to make this estimate is nonsense. But that's not a story they like to tell. I talked about this in more detail in a recent video. Five, time stops at the speed of light. That idea is a weird way to say that light doesn't have an internal notion of time. You see, for us, time passes at 1 second a second. As I said, it's called the proper time. But for anything that moves at the speed of light, the proper time is equal to zero always. This is why it's reasonable to say that for light itself, everything happens at once. I explained this in an earlier video, but it's not like if you run faster, then time runs slower. Time only runs slower if you accelerate. That said, I need to follow this up immediately with another common misunderstanding that time slows down in Einstein's theory is just an illusion or an apparent effect to do with measurements. That's not true. If you have a clock that's accelerated and you compare it to one that isn't accelerated, then the accelerated one tick slower. An important special case of this is sitting still in a gravitational field, as you probably do now, because that means you're accelerated. And the stronger the gravitational pull at your location, the slower you age. This means that for example time on the surface of earth passes a little bit more slowly than on the surface of the moon. It's a measurable real effect but it's so tiny that it doesn't matter unless you need to synchronize something to nanoc accuracy. This is why NASA wants to introduce a moon time that's separate from earth time because these two times can't be synchronized. They just run at different speeds. Four, quantum particles exchange information faster than light. No, they don't. I think the reason people get confused about this is because of all the talk about Einstein's spooky action at a distance that if you trust the popular science headlines has been proven to exist. But that's not the case. What's been proven to exist is entanglement. That's a correlation and it's not Einstein spooky action. No, entangled particles do not non-locally influence each other. No, they don't. And no, you can't use them to send information faster than light. No, the so-called quantum teleportation is not an exception. In fact, there is a mathematical theorem which formally proves that no matter what experiment you do or what protocol you use, you can't use quantum effects to send information faster than light. This brings me to three. Einstein was wrong about quantum physics. People who say this usually don't know what Einstein said in the first place. His famous remark that God doesn't play dice was for one thing clearly a joke, but also it's impossible to prove that the world is either deterministic or indeterministic. So this statement will never be shown to be either true or false. What Einstein did say about quantum mechanics is that he didn't believe that the collapse of the wave function is the physical process. This collapse is what he called a spooky action at a distance because it happens faster than light. There is to date no experiment that shows that the spooky action is actually physically real. So no, Einstein's beliefs about quantum physics have never been shown to be wrong. Second, dark energy is a sort of anti-gravity. Dark energy is what causes the expansion of the universe to speed up. Anti-gravity will require something that's repelled by our normal matter but attracted to itself. This means dark energy would clump which it doesn't. Hence, dark energy is not anti-gravity. I suspect that this misunderstanding comes from thinking that anti-gravitating mass or energy would just repel everything including itself. However, that can't be because one can calculate the behavior from the spin of the carrier force. You see, for electric charges, the carriers the photon that has spin one. It follows from this that unlike charges attract, like charges repel. For gravity, the career force has spin two and it's the other way round. Like charges attract, unlike charges repel, where the charge is now the mass. You find that calculation in the Fineman lectures. Why have we never observed anti-gravitating mass. Good topic for your PhD thesis, maybe. And finally, number one, faster than light travels incompatible with Einstein's theories. That isn't true. You can totally have faster than light travel in Einstein's theories. What is true is that Einstein's theory also tells you that it takes an infinite amount of energy to accelerate from below the speed of light to above the speed of light. Doesn't that kind of mean the same thing. Isn't Sabina just nitpicking here. No, I think this distinction matters because in any other instance in which physicists encounter something becoming infinitely large, they say that's not physically real. It just means that the theory breaks down. I think it's the same for faster than light travel. It's not impossible, just difficult. Did I miss any major physics myth. Let me know in the comments. The bigger message for today is that learning physics from the popular science media is not the best way to go about it. If you want to brush up your physics skills, I recommend you check out Brilliant. Brilliant offers courses on a large variety of topics in science, computer science, and mathematics. All their courses have interactive visualizations and come with follow-up questions. Whether you want to learn to think like an engineer, brush up your knowledge of algebra, or want to learn coding and Python, Brilliant has you covered. It's a fast and easy way to learn, and you can do it whenever and wherever you have the time, and they're adding new courses each month. I really enjoy the courses on Brilliant because they convey a lot of knowledge very quickly. If that sounds like the right thing for you, use my link, brilliant.org/sabina, org/subena to give it a try. First 30 days are free and with this link you'll get 20% off the annual premium subscription. It's an easy way to learn more and to support this channel. Thanks for watching. See you tomorrow.