Rotational symmetry → angular momentum

18:56experiment anywhere and the translation of space is going to work. But there is a fundamental scale, right? That has to do with like how big atoms are. If you want to get really really nitty-gritty about it, there's a fundamental scale that's the plank length that has to do with like how big how how how you know close I can get electrons before they turn into black holes. But but there is such a thing, right? There's some meter stick. Yes. That that's here. And so this is actually something that um was first found by Galileo um in Galileo's dialogue concerning two new sciences. He published this thing. Um he had a really funny cartoon. He he he thought about like animals and what would happen if I had like a Clifford sized dog. >> Okay.

19:36>> Okay. Remember Clifford the big red dog? Yeah. So it's like I got I got a normal dog and then I got a Clifford sized dog. What would happen? Well, the Clifford sized dog um your your mass your weight scales like your volume, right? So it's going to go like the length cubed. >> Okay? >> Right? Uh the how much stuff you have goes like length cubed because volume goes like length cubed. On the other hand, tensile strength goes like length squared because it has to do with the cross-sectional area of your bone. >> Yeah. Yeah. Yeah. >> You notice that? >> So, I was just watching a video about this person hanging from rubber bands and seeing how many rubber bands it took to hold their weight up. And part of the discussion was about the tensil strength

20:18that is in the rubber bands in order to enable >> Yeah. holding it up holding. >> Exactly. Like if he had a that guy if he had a chain of rubber bands that wouldn't really help him. On the other hand, if he had a bunch of rubber bands in parallel, that would help him because the rubber bands in parallel would increase the the cross-sectional area of how much is holding you up. Bingo, right? And so, um, Galileo has this really cool cartoon of like what what a superdog bone would look like compared to a normal dog where the normal dog is like this like small bone. This is one of his drawings. And then the super dog bone is just massive, [laughter] but not so much scaled in the in the along the bone length, but like the air

20:59the the thickness of the bone is way bigger.