Adam Frank
speaker
594 appearances
1 recordings
1 series
first heard Dec 2024
last heard Dec 2024
Adam Frank’s voice in public audio — every appearance, attributed to the second.
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Appearances
He'd done the calculation in his head and he suddenly realized that, look, if one, if they're, you know, if intelligence is common, that even traveling at sub light speeds, a, a civilization could cross, you know, kind of hop from one star system to the other and spread out across the entire galaxy in a few hundred thousand years. And he realized this. And so he was like, why aren't they here now?
And that was the beginning of the Fermi paradox. It actually got picked up as a formal thing in 1975 in a paper by Hart, where he actually kind of went through this calculation and showed and said, well, there's nobody here now. Therefore, there's nobody anywhere that, you know. Okay, so that is what we will call the direct Fermi paradox. Why aren't they here now?
But something happened where people, after SETI began, where people started to, there was this idea of the great silence. People got this idea in their head that like, oh, we've been looking for decades now for signals of extraterrestrial intelligence and we haven't found any. Therefore, there's nothing out there. So we'll call that the indirect Fermi paradox.
And there absolutely is no indirect Fermi paradox for the most mundane of reasons, which is money. There's never been any money to look. SETI was always done by researchers who were kind of like scabbing some time, you know, some extra time from their other projects to, you know, look a little bit better. You know, at the sky with a telescope. Telescopes are expensive.
So Jason Wright, one of my collaborators, he and his students did a study where they looked at the entire search space for SETI. You know, and imagine that's an ocean. All the different stars you have to look at, the radio frequencies you have to look at, how when you look, how often you look. And then they summed up all the SETI searches that had ever been done. They went through the literature.
And what they found was if that search space, if the sky is an ocean and you're looking for fish, how much of the ocean have we looked at? And it turns out to be a hot tub. That's how much of the ocean that we've looked up. We've dragged a hot tub's worth of ocean water up, and there was no fish in it. And so now are we going to say, oh, well, there's no fish in the ocean, right?
So there is absolutely, positively no indirect Fermi Paris. We just haven't looked. Um, but we're starting to look, so that's what's, you know, finally we're starting to look. That's what's exciting. The direct Fermi paradox. There are so many ways out of that, right? There's a book called 77 solutions to the Fermi paradox that it just, you know, you can pick your favorite one.
It just doesn't carry a lot of weight because there's so many ways around it. We did an actual simulation, my group, Jonathan Carroll, one of my collaborators, we actually simulated the galaxy and we simulated probes moving at sublight speed from one star to the other, gathering resources, heading to the next one.
And so we could actually track the expansion wave across the galaxy, have one IABiogenesis event, and then watch the whole galaxy get colonized or settled. And it is absolutely true that that wave crosses, you know, Hart was right, Fermi was right, that wave crosses very quickly. But civilizations don't last forever, right? So one question is, when did they visit?
When did they come to Earth, right? So if you give civilizations a finite lifetime, let them last 10,000, 100,000 years, what you find is you now have a steady state. Civilizations are dying, they're coming back, they're traveling between the stars. What you find then is you can have big holes opened up. You can have regions of space where there is nobody. For, you know, millions of years.
And so if that, if we're living in one of those bubbles right now, then maybe we were visited, but we were visited a hundred million years ago. And there was a paper that Gavin Schmidt and I did that showed that if there was a civilization, whether it was like dinosaurs or aliens that was here a hundred million years ago, there's no way to tell. There's just there's no record left over.
The fossil record is too sparse. The only way maybe you could tell is by looking at the isotopic strata to see if there was anything reminiscent of an industrial civilization. But the idea that, you know, you'd be able to find, you know, iPhones or toppled buildings after 100 million years is there's no way.
Even a large civilization, even if it was a large. A hundred million years ago. And it lasted 10,000 years, fossil record's not going to have it. Yeah, yeah. The fossil record is too sparse, right? Most things don't fossilize. And 10,000 years is a blink in the eye of geological time.
So Gavin called this the Silurian hypothesis after the Doctor Who episode with the lizard creatures, the Silurians. But that paper got a lot of press. But it was an important idea. And this was really Gavin's. I was just helping with the astrobiology. To recognize that, yeah, we could have been visited a long time ago. There just would be no record. Yeah. It's kind of mind blowing.
Very short amount of time. Yeah. This is not to say that there was like, so whenever I gave, you know, I like what I was on Joe Rogan for exactly this paper. And I had to always emphasize, we're not saying there was a Silurian, you know, but we're just saying that if there was. That's why I love Gavin's question. Gavin's question was just like, how could you tell, right?
It was a very beautifully scientific question. That's what we were really showing is that you really, you know, unless you did a very specific kind of search, which nobody's done so far, that, you know, there's not an obvious way to tell that there could have been civilizations here earlier on.
Yeah, like the Amazon, like the Amazon problem. That was, you know, the conquisters came and wiped everybody out. And especially just even like the plague may have decimated. So yeah, how much of that civilization? And there's a lot of theories.
Yeah. Well, like the, the, the indigenous peoples of North America, there could have been like millions and millions. You know, we get this idea that like, oh, you know, this, the Europeans came and it was empty, you know, but it was, may have only been empty because the plague had swept up from the, you know, from the, what happened in Mesoamerica.
So, and yeah, and they didn't really build cities, but they had, they, I mean, they, they didn't build wooden or stone cities. They built wooden cities, you know,
Why does that apply?
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