#468 – Janna Levin: Black Holes, Wormholes, Aliens, Paradoxes & Extra Dimensions
Episode publishedPodcast: Lex Fridman PodcastLex Fridman Podcast
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The following is a conversation with Jenna Levin, a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves in space time. She has also written some incredible books, including how the universe got its spots on the topic of the shape and the size of the universe, a madman dreams of touring machines on the topic of genius, madness, and the limits of knowledge, black hole blues, and other songs from outer space, on the topic of LIGO and the detection of gravitational waves, and black hole survival guide,
Classic. Sydney was beloved.
I think all the best thoughts, honestly. Mhmm. Maybe the worst thoughts too are all come at night. There's something there's something about the night. Maybe it's the silence. Mhmm. Maybe it's the peace all around. Maybe it's the darkness, and you just Mhmm. You could be with yourself and you could think deeply.
I feel like there's stolen hours in the middle of the night because it's not busy. Your gadgets aren't pinging. There's really no pressure to do anything, but I'm often awake in the middle of the night. And so it's sort of like these extra hours of the day. I think we were exchanging messages at four in the morning.
Okay. So in that way, many other ways were kindred spirits. Mhmm. So let's go. In the one of the coolest objects in the universe, black holes, what are they? And maybe even a good way to start is to talk about how are they formed.
Yeah. In a way, people often confuse how they're formed with the concept of the black hole in the first place. So when black holes were first proposed, Einstein was very surprised that such a solution could be found so quickly, but he really thought nature would protect us from their formation. And then nature thinks of a way. Nature thinks of a way to make these crazy objects, which is to kill off a few stars. But then I think that there's a confusion that dead stars, these very, very massive stars that die, are synonymous with the phenomenon of black hole. And it's really not the case. Black
he
was an astronomer, who had enlisted in his forties. And he finds this really remarkable solution to Einstein's equations, and it's the first exact solution. He doesn't call it a black hole. It's not called a black hole for decades. But what I love about what Schwarzschild did is it's a thought experiment. It's not about observations. It's not about making these things in nature. It's really just about the idea. He sets up this completely untenable situation. He says, imagine I crush all the mass of a star to a point. Don't ask how that's done because that's really absurd. But let's just preten
maybe the purpose of the thought experiment was to find the limitations of the theory. So you you find the most extreme versions in order to understand where it breaks down. Yeah. And it just so happens in this case that might actually predict these extreme kinds of objects.
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