url stringlengths 28 28 | title stringlengths 43 71 | published stringlengths 20 20 | id stringlengths 16 31 | videoId stringlengths 11 11 | text stringlengths 1 504 | start float64 0 7.84k | end float64 3.42 7.87k |
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https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2651.08 | Xwpd_z-ipu4 | Well, in quantum field theory, the answer is clearly infinity. They're an infinite number of degrees of freedom, but it's still an interesting question to address because there are different sources of infinity. So let me be clear here. | 2,651.08 | 2,665.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2665.08 | Xwpd_z-ipu4 | There's an uninteresting sense of infinity in this case, which is if you just have infinity times infinity, or infinity plus infinity, you still get infinity. | 2,665.08 | 2,676.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2676.08 | Xwpd_z-ipu4 | That's what you're going to get one way or the other, but it's not any bigger. Infinity plus infinity is the same infinity that you had when you added the two infinities together. | 2,676.08 | 2,685.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2685.08 | Xwpd_z-ipu4 | There's a whole complicated, well, not really complicated, but subtle and careful mathematical analysis about how big different kinds of infinities are. | 2,685.08 | 2,694.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2694.08 | Xwpd_z-ipu4 | There are more real numbers than there are integers, even though they're both infinitely big, but when you add them together, you get whatever the biggest infinity is. | 2,694.08 | 2,701.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2701.08 | Xwpd_z-ipu4 | You don't get a bigger infinity than you started with. | 2,701.08 | 2,704.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2704.08 | Xwpd_z-ipu4 | That's not what we're talking about here. That's how I'm going to worry about here anyway. | 2,704.08 | 2,707.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2707.08 | Xwpd_z-ipu4 | Whether the infinities we're talking about are discrete or continuous, etc. is not what I'm interested in. What I'm interested in is why are there infinities at all? | 2,707.08 | 2,716.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2716.08 | Xwpd_z-ipu4 | So there's actually three different sources for there being an infinite number of degrees of freedom in quantum field theory, and they're all kind of important and kind of different. | 2,716.08 | 2,726.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2726.08 | Xwpd_z-ipu4 | So one source of infinity is that space is infinite. That is one reason why there's an infinite number of degrees of freedom. | 2,726.08 | 2,736.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2736.08 | Xwpd_z-ipu4 | Just imagine that you have space and you divide it up into little sub-regions. | 2,736.08 | 2,743.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2743.08 | Xwpd_z-ipu4 | And you can remember we said in one of these videos, I don't know, I've done a lot of videos. It's in lockdown. | 2,743.08 | 2,752.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2752.08 | Xwpd_z-ipu4 | So that's a very important question. | 2,752.08 | 2,755.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2755.08 | Xwpd_z-ipu4 | I think it was the Q&A for fields that I talked about, the entanglement structure of empty space, of the vacuum for quantum fields. | 2,755.08 | 2,766.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2766.08 | Xwpd_z-ipu4 | And I said, you could divide up space. And you could say, well, here's what's going on in that region of space. | 2,766.08 | 2,771.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2771.08 | Xwpd_z-ipu4 | Here's what's going on in that region. I said they're entangled, etc. | 2,771.08 | 2,775.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2775.08 | Xwpd_z-ipu4 | So if I did that, even if I only had one degree of freedom per region of space, there's an infinite number of regions of space. | 2,775.08 | 2,784.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2784.08 | Xwpd_z-ipu4 | So that's a sort of simple and cheap infinity. This would be because it's large distances, large amounts of space that are contributing this infinite number of degrees of freedom. | 2,784.08 | 2,797.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2797.08 | Xwpd_z-ipu4 | This is what is called an infrared divergence, if you like. It's not quite abusing the notation a little bit here, but this is simply because space is big. | 2,797.08 | 2,808.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2808.08 | Xwpd_z-ipu4 | This is like saying if I have an infinitely big universe with a finite number of particles per cubic centimeter, I would have an infinite number of particles, even in classical mechanics. | 2,808.08 | 2,818.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2818.08 | Xwpd_z-ipu4 | So that's a kind of infinity, but it's not a specifically fundamental quantum mechanical or quantum field theory kind of infinity. Okay? | 2,818.08 | 2,827.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2827.08 | Xwpd_z-ipu4 | It's just because space is big. So we can say, let's look at a box. Let's look at a box of finite size. | 2,827.08 | 2,839.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2839.08 | Xwpd_z-ipu4 | This is called putting an infrared cut off on our theory. We're only going to look at a box of finite size. | 2,839.08 | 2,848.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2848.08 | Xwpd_z-ipu4 | So here is by a box, I just made a region of space. I don't mean a physical box. You don't need to bring cardboard or wood out or anything like that. | 2,848.08 | 2,854.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2854.08 | Xwpd_z-ipu4 | I mean, just consider hypothetically in your brain a region of space with some fixed size. Let's say L. We're not going to go into details here, but we're going to get rid of the annoying infinity because space is infinitely big by asking how many degrees of freedom are there in a box. | 2,854.08 | 2,872.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2872.08 | Xwpd_z-ipu4 | Let's say one centimeter on each side. Okay. Well, guess what? There's an infinite number of degrees of freedom inside the box. | 2,872.08 | 2,880.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2880.08 | Xwpd_z-ipu4 | And that is because there are an infinite number of wavelengths that you can fit inside that box. | 2,880.08 | 2,889.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2889.08 | Xwpd_z-ipu4 | So I can have, you know, I can fit this kind of wave inside that box that has sort of one full up and down wave from one side of the box to the other. | 2,889.08 | 2,900.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2900.08 | Xwpd_z-ipu4 | I can also fit this wave inside the box that does that twice. We can talk about whether or not you want to fit half integers or whatever inside the box, but the point is I can just keep going. | 2,900.08 | 2,914.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2914.08 | Xwpd_z-ipu4 | I can make all sorts of wavelengths and put them inside the box and you can't stop me. | 2,914.08 | 2,921.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2921.08 | Xwpd_z-ipu4 | And there's I can make the wavelength that I consider smaller and smaller and smaller until it goes to zero size. So if I count how many different wavelengths I can fit in the box. | 2,921.08 | 2,933.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2933.08 | Xwpd_z-ipu4 | They're an infinite number. So there are an infinite number of distinct modes in a box. So infinite number of modes in any box of size L. | 2,933.08 | 2,950.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2950.08 | Xwpd_z-ipu4 | So that's an infinity, and that is a more interesting infinity in some sense. It's not just because space is big. This is now an intrinsic feature of quantum field theory, because it comes from starting from the assumption that we have | 2,950.08 | 2,967.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2967.08 | Xwpd_z-ipu4 | an infinite number that we have a field that is smooth and continuous. Okay. That's redundant, a smooth field. That is to say, a field that exists with a different value at literally every point in space. | 2,967.08 | 2,979.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2979.08 | Xwpd_z-ipu4 | And that space itself is smooth. So the field is defined an infinite number of points. Therefore, if you decompose into wavelengths, there are an infinite number of wavelengths. | 2,979.08 | 2,988.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2988.08 | Xwpd_z-ipu4 | And this, I say, is more interesting because here you might begin to doubt that you actually believe what quantum field theory is telling you, right? We haven't added gravity into the game yet. | 2,988.08 | 2,999.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t2999.08 | Xwpd_z-ipu4 | But when we do add gravity in, there'll be something called the Planck length after Max Planck, the German physicist, who used his new constant of nature to make these fundamental units of energy and mass and time and so forth. | 2,999.08 | 3,013.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3013.08 | Xwpd_z-ipu4 | Without gravity, if gravity is not important, Newton's constant does not appear in the game, and you can't make the Planck length. You can't construct that number without Newton's constant. | 3,013.08 | 3,024.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3024.08 | Xwpd_z-ipu4 | So if you're just doing quantum field theory without gravity, which is what most quantum field theorists do, right, in all particle physicists, they just ignore gravity, there's no such thing as the Planck length and quantum field theory by itself extends down to arbitrarily small wavelengths down to zero wavelengths. | 3,024.08 | 3,040.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3040.08 | Xwpd_z-ipu4 | And remember, wavelengths are inversely proportional to energy, right, you know, very roughly speaking, the energy of a mode goes as one over the wavelength. I say very roughly because there are two pies, I'm not going to get right. | 3,040.08 | 3,053.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3053.08 | Xwpd_z-ipu4 | So, modes become higher and higher energy as their wavelengths become shorter and shorter, and there are an infinite number of them that you can talk about. | 3,053.08 | 3,062.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3062.08 | Xwpd_z-ipu4 | But you might suspect that once you include gravity, once you admit that gravity exists in the real world, this infinity might go away, right, this might be an artifact of taking quantum field theory seriously in a regime where you shouldn't be taking it seriously. | 3,062.08 | 3,080.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3080.08 | Xwpd_z-ipu4 | So that's why it's a more interesting infinity because it's a little more problematic, it's a little bit less certain that it exists in the real world. I mean, there's the formalism of quantum field theory that we use, do calculations, and we trust in a certain regime. | 3,080.08 | 3,095.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3095.08 | Xwpd_z-ipu4 | But then there's what happens in the real world outside that regime, okay, and quantum field theory says what happens, but it might not be right, it might not be correct. So this is an infinity, this is a source of an infinite number of degrees of freedom that may or may not be part of the real world. | 3,095.08 | 3,111.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3111.08 | Xwpd_z-ipu4 | So, you could say, okay, let's put a, so consider a smallest wavelength. In other words, let's just say by hand that we are only going to consider wavelengths between what should we call it. | 3,111.08 | 3,133.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3133.08 | Xwpd_z-ipu4 | So, you said lambda, we used L, yeah, I used all the good letters, K, I don't know, K is a wavelength, okay, and it is the smallest possible wavelength so all real wavelengths are between the size of the box, and this tiny little number K. So in other words, I'm now considering a box, which has a size L, across, my box... | 3,133.08 | 3,162.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3162.08 | Xwpd_z-ipu4 | But there's also sort of a smallest possible sub box inside, okay, and this has size K across. | 3,162.08 | 3,173.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3173.08 | Xwpd_z-ipu4 | I heard news K because K is what we use for the wave number, right, what is the number that we haven't used yet, Hijk, J, there you go, J. | 3,173.08 | 3,187.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3187.08 | Xwpd_z-ipu4 | People usually just use subscripts for this, but I'm trying to avoid subscripts as much as I can. So, there's a, I'm just inventing this, this is not part of quantum field theory, I'm just saying, let's contemplate what happens. | 3,187.08 | 3,197.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3197.08 | Xwpd_z-ipu4 | Let's contemplate when we have a smallest wavelength, we will allow ourselves to contemplate. | 3,197.08 | 3,202.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3202.08 | Xwpd_z-ipu4 | Maybe it's the Planck length, but we're just being open minded, we're saying there's a smallest possible wavelength, and there's a largest possible wavelength because we have a box that we're considering. | 3,202.08 | 3,211.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3211.08 | Xwpd_z-ipu4 | So you might think now that there's a smallest wavelength and a largest wavelength, there's a finite number of wavelengths that I need to consider inside the box, therefore there are a finite number of degrees of freedom. | 3,211.08 | 3,223.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3223.08 | Xwpd_z-ipu4 | But that's wrong, that's still wrong because there's a third source of, it's a third infinity, which is that each mode is a simple harmonic oscillator, right? | 3,223.08 | 3,237.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3237.08 | Xwpd_z-ipu4 | Or is mathematically equivalent to a simple harmonic oscillator. | 3,237.08 | 3,242.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3242.08 | Xwpd_z-ipu4 | And what that means is, just to be super duper clear here, pick a mode of a certain wavelength, certain fixed wavelength, let's say this one, okay, so that is a wavelength smaller than L, but larger than J. | 3,242.08 | 3,259.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3259.08 | Xwpd_z-ipu4 | So the wavelength here is this, okay, starting from here and going back to the same point. | 3,259.08 | 3,268.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3268.08 | Xwpd_z-ipu4 | So this is an allowed wavelength, therefore it's an allowed mode, but what we showed is that the quantum mechanical description of that mode is equivalent to a simple harmonic oscillator, which means that that mode of fixed wavelength has a lowest energy state. | 3,268.08 | 3,283.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3283.08 | Xwpd_z-ipu4 | It has a next highest energy state, a next highest energy state, and an infinite number of energy states, okay? | 3,283.08 | 3,289.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3289.08 | Xwpd_z-ipu4 | So every mode has an infinite number of energy states, and that implies an infinite number of degrees of freedom. | 3,289.08 | 3,302.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3302.08 | Xwpd_z-ipu4 | So this is a third way, how many we have here? | 3,302.08 | 3,306.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3306.08 | Xwpd_z-ipu4 | Yeah, a third way in which you can get an infinite number of degrees of freedom and quantum field theory. There's an infinite number of places the thing could be. | 3,306.08 | 3,315.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3315.08 | Xwpd_z-ipu4 | In any one place, in any one box, there's an infinite number of wavelengths the mode could have. | 3,315.08 | 3,321.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3321.08 | Xwpd_z-ipu4 | And for any one wavelength, there's an infinite number of energies that it could have, because it's like a simple harmonic oscillator. | 3,321.08 | 3,327.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3327.08 | Xwpd_z-ipu4 | Now this is also something that you might begin to doubt in the context of gravity, because if you have a box of fixed size and you put an infinite amount of energy in it, or some very, very large amount of energy in it, it will collapse to make a black hole. | 3,327.08 | 3,343.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3343.08 | Xwpd_z-ipu4 | And black holes, whatever we might know about them, black holes are not simple perturbations of flat spacetime, okay? Black holes are probably not even described by quantum field theory at all. | 3,343.08 | 3,354.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3354.08 | Xwpd_z-ipu4 | This is why quantum gravity is difficult and subtle, and you need to go beyond simple-minded quantum field theory to do quantum gravity. | 3,354.08 | 3,362.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3362.08 | Xwpd_z-ipu4 | So you can put another cut off, you can put an energy cut off, which was sort of invented by Jacob Beckenstein. | 3,362.08 | 3,369.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3369.08 | Xwpd_z-ipu4 | The Beckenstein bound, he phrased it in terms of an amount of energy, but it's the same basic idea, he said, don't include energies for wavelengths such that the amount of energy in the box would make a black hole. | 3,369.08 | 3,385.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3385.08 | Xwpd_z-ipu4 | There's a cut off there as well. | 3,385.08 | 3,388.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3388.08 | Xwpd_z-ipu4 | Again, we don't know if that's true or not. | 3,388.08 | 3,390.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3390.08 | Xwpd_z-ipu4 | I mean, this is right at the edge of what we understand in modern physics. We understand this, okay, space could be big. | 3,390.08 | 3,400.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3400.08 | Xwpd_z-ipu4 | Let's imagine that we just look at space piece by piece. | 3,400.08 | 3,403.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3403.08 | Xwpd_z-ipu4 | But here, for the number of wavelengths, the smallest wavelength, and the amount of energy per wavelength, these are different phenomena that only come up when gravity is important. | 3,403.08 | 3,414.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3414.08 | Xwpd_z-ipu4 | And we know that gravity is important, but we don't know what to do about it. We don't have the once and for all quantum theory of gravity. | 3,414.08 | 3,420.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3420.08 | Xwpd_z-ipu4 | So we make these sort of haphazard guesses, or we try to invent a quantum theory of gravity. | 3,420.08 | 3,425.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3425.08 | Xwpd_z-ipu4 | You could try to do string theory or loop quantum gravity and say that within those theories, there are specific answers to these questions, but we don't know which theory is right. | 3,425.08 | 3,434.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3434.08 | Xwpd_z-ipu4 | So we don't know what the final answer to these questions are yet. | 3,434.08 | 3,437.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3437.08 | Xwpd_z-ipu4 | So anyway, long story short, in quantum field theory, there are an infinite number of degrees of freedom, not just overall, but even in any one little sized box. | 3,437.08 | 3,447.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3447.08 | Xwpd_z-ipu4 | And that is a clue that quantum field theory is not the final story, that quantum field theory is not the way that nature works at a fundamental level. | 3,447.08 | 3,456.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3456.08 | Xwpd_z-ipu4 | I want you to be able to hold these two ideas in your head at the same time. | 3,456.08 | 3,459.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3459.08 | Xwpd_z-ipu4 | Quantum field theory is the best theory we currently have of the way nature works. | 3,459.08 | 3,464.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3464.08 | Xwpd_z-ipu4 | And quantum field theory is probably not the way nature works. This is part of this story that I've said before that we're in a situation where we have theories that fit the data really, really well, but are not the final answer. | 3,464.08 | 3,474.08 |
https://youtu.be/Xwpd_z-ipu4 | The Biggest Ideas in the Universe | Q&A 10 - Interactions | 2020-05-29T22:33:18Z | Xwpd_z-ipu4-t3474.08 | Xwpd_z-ipu4 | That's why physics is not done yet. That's why we have to keep going. That's why it's important to inspire new generations of young people to think about these big ideas, because I'm optimistic that eventually we will figure this stuff out. | 3,474.08 | 3,503.08 |
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