Episode #455
Adam Frank: Alien Civilizations and the Search for Extraterrestrial Life
Adam Frank is an astrophysicist studying star systems and the search for extraterrestrial life and alien civilizations. Thank you for listening ❤ Check out our sponsors: https://lexfridman.com/sponsors/ep455-sc See below for timestamps, transcript, and to give feedback, submit questions, contact Lex, etc.
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What this episode covers
Adam Frank is an astrophysicist studying star systems and the search for extraterrestrial life and alien civilizations. Thank you for listening ❤ Check out our sponsors: https://lexfridman.com/sponsors/ep455-sc See below for timestamps, transcript, and to give feedback, submit questions, contact Lex, etc.
Where to start
Introduction
If we don't ask how long they last, but instead ask what's the probability that there have been any civilizations at all, now matter how long they lasted. I'm not asking whether they exist now or not, I'm just asking in general about probabilities to make a technological civilization anywhere and at any time in the history of the university. That, we're able to constrain. What we found was basically that there have been 10 billion trillion habitable zone planets in the universe. What that means is those are 10 billion trillion experiments that have been run. The only way that we're the only time that this whole process from abiogenesis to a civilization has occurred is if everyone one of those experiments failed. Therefore, you could put a probability, we called it the Pessimism Line. We don't really know what nature sets for the probability of making intelligent civilizations, but we could set a limit using this. We could say, look, if the probability per habitable zone planet is less than 10 to the minus-22, one in 10 billion trillion, then yeah, we're alone. If it's anywhere larger than that, then we're not the first. It's happened somewhere else. To me, that was mind-blowing. It doesn't tell me there's anybody nearby, the galaxy could be sterile. It just told me that unless nature's really has some bias against civilizations, we're not the first time this has happened. This has happened elsewhere over the course of cosmic history.
Start at 0:00
Planet formation
You wrote a book about aliens. The big question, how many alien civilizations are out there? Yeah, that's the question. The amazing thing is that, after two-and-a-half millennia of people yelling at each other, or setting each other on fire occasionally over the answer, we now actually have the capacity to answer that question. In the next 10, 20, 30 years, we're going to have data relevant to the answer to that question. We're going to have hard data finally that will, one way or the other ... Even if we don't find anything immediately, we will have gone through a number of planets. We'll be able to start putting limits on how common life is.
Start at 1:58
Plate tectonics
Yeah, I think we can. I think we're learning how to do that now. One part is trying to just figure out how planets form themselves in doing the simulations. That cascade from dust grains up to planetary embryos, that's hard to simulate because you got to do both the gas, and you got to do the dust and the dust colliding, and all that physics. Once you get up to a planet-sized body, then you have to switch over to almost a different kind of simulation. Often what you're doing is you're assuming the planet this this spherical ball, and then you're doing a 1D, a radial calculation. You're just asking, "All right, what is the structure of it going to be? Am I going to have a solid iron core, or am I going to get a solid iron core with a liquid iron core out around it?" Like we have on Earth. Then you get a silicate, rocky mantle, and then a crust. All those details, those are beyond being able to do full 3D simulations from Ab Initio, from scratch. We're not there yet.
Start at 7:08
People and topics
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Key takeaways
- Introduction
- Planet formation
- Plate tectonics
- Extinction events