The philosophy of beauty in equations

49:45levels of an atom, the electron is in some energy state and then it goes to another energy state and >> and they're discreet. >> Yeah. And they're discreet. And when that transition happens, it lets out light. And by measuring the light, you can tell what kind of transition that happened. Well, he found that there's certain transitions that never happen. >> Okay. >> Okay. If the electron is in some state, it's never going to go to some of these other states. Okay. And Eugene Wignner created these things called selection rules. Okay. Turns out that atoms have different two kinds of energy levels. There's one that has even parody which means that if I flip the coordinates it's the same. That's the one like if it's symmetric about the y-axis, right?

50:26And if I flip it's like the Taj Mahal. And then there's another one where if I flip the parody, it's going to be the negative of that. It's like it's like a flippingness of the Taj Mahal. Okay. But there's one state that looks like the Taj Mahal and then there's another state that looks exactly the opposite. Okay. And what he found was that >> when these electrons switch energy levels, they have to conserve par. Okay. One of them is even, the other one is odd. You can assign them numbers that are even and odd. And the total par before has to equal the total par after. So it became and and everybody liked it, right? It's like, okay, it's like intuitive, right? If I made a clock that's in the that's in this opposite

51:09mirror world, then it works the same way. >> Conservation of par comes from not theorem. So, it's all nice. >> It's all tracking. >> It's all tracking. The universe the universe can't distinguish between left and right. We're in a nice universe that's just agnostic about what is left and right. It doesn't care. Okay. Then comes the puzzle of the theta and the toao. Okay. These are maison. Maison are um at the time they didn't know what it was but um this was at now we know that a maison is basically a quark and anti-quark bound together in a single particle at the time we didn't know what it was in the 1950s these physicists

51:49they found two particles the theta and the toao okay and they were same the same in every regard okay they had the same mass they had the same charge they had the same lifetime even the lifetime part is weird Okay? Cuz they got the same lifetime, but they're different in one tiny thing. Okay? And the one tiny thing is in how they decay. One of them decayed into two pions, and the other one decayed into three pions. It's not important what pions are. The main point is pions carry a par charge. Okay? You know how I was saying that we can assign par numbers to our states? Well, pions have par numbers. And all of a sudden you had two identical particles in every