David Kipping: Alien Civilizations and Habitable Worlds | Lex Fridman Podcast #355

I think it's actually not that hard to imagine we are the only civilization in the galaxy right now.

Living.

Yeah, that's currently extant. But there may be very many extinct civilizations. If each civilization has a typical lifetime comparable to, let's say, AI is the demise of our own, that's only a few hundred years of technological development, or maybe 10,000 years if you go back to the Neolithic re- revolution, the dawn of agriculture, you know, hardly anything in cosmic time span. Um, that- that's nothing. That's the blink of an eye. And so it's not surprising at all that we would happen not to co-exist with anyone else.

Mm-hmm.

But that doesn't mean nobody else was ever here. And if other civilizations come to that same conclusion and realization, maybe they scour the galaxy around them, don't find any evidence for intelligence, then they have two options. They can either give up on communication and just say, "Well, it's never gonna happen, uh, we just, may as well just, you know, worry about what's happening here on our own planet," or they could attempt communication, but communication through time.

The following is a conversation with David Kipping, an astronomer and astrophysicist at Columbia University, Director of the Cool Worlds Lab, and he's an amazing educator about the most fascinating scientific phenomena in our universe. I highly recommend you check out his videos on the Cool Worlds YouTube channel. David quickly became one of my favorite human beings. I hope to talk to him, uh, many more times in the future. This is a Lex Friedman podcast. To support it, please check out our sponsors in the description. And now, dear friends, here's David Kipping. Your research at Columbia is in part focused on what you call cool worlds, or worlds outside our solar system where temperature is sufficiently cool to allow for moons, rings, and life to form, and for us humans to observe it. So can you tell me more about this idea, this place of cool worlds?

Yeah. The history of discovering planets outside our solar system was really dominated by these hot planets. And that's just because of the fact they're easier to find. When the very first methods came online, these were primarily the Doppler spectroscopy method, looking for wobbling stars, um, and also the transit method. And these two both have a really strong bias towards finding these hot planets. Now, hot planets are interesting. The chemistry in their atmosphere is fascinating. It's very alien. Um, an example of one that's particularly close to my heart is TrES-2b, whose atmosphere is so dark it's less reflective than coal. And so they have really bizarre photometric properties, yet at the same time, they resemble nothing like our own home. And so, they said there's two types of astrophysicists, the astrophysicists who care about how the universe works, they wanna understand the mechanics of the machinery of this universe, why did the Big Bang happen, why is the universe expanding, how are galaxies formed, and there's another type of astrophysicist which perhaps, um, speaks to me a little bit more, it whispers into your ear, and that is, why are we here, are we alone, are there others out there? And ultimately along this journey, the hot planets aren't gonna get us there. We- when we're looking for life in the universe, seems to make perfect sense that there should be planets like our own out there, maybe even moons like our own planet around gas giants that could be habitable. And so my research has been driven by trying to find these more treacherous globes that might resemble our own planet.