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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And that's exactly where there are no planets in our solar system. So, um, the smaller ones of those we call super earths, the larger ones we call sub Neptunes. And they're anybody's guess. Like we don't really know what happens to material when you're squeezed to those pressures, which is like millions, tens of millions of times the pressure on the surface of the earth.
So those details really will matter of what's going on in there because that will determine whether or not you have, say, for example, plate tectonics. We think plate tectonics may have been really important for life on earth, for the evolution of complex life on earth.
So it turns out, and this is sort of the next generation where we're going with the understanding the evolution of planets in life. It turns out that you actually have to think hard about the planetary context for life. You can't just be like, oh, there's a warm pond, you know, and then some interesting, you know, chemistry happens in the warm pond.
You actually have to think about the planet as a whole and what it's gone through in order to really understand whether a planet is a good place for life or not.
There's a bunch of different things. One is that, you know, the Earth went through a couple of phases of being a snowball planet. Like, you know, we went into a period of glaciation where pretty much the entire planet was under ice. The oceans were frozen. You know, early on in Earth history, there was barely any land.
We were actually a water world, you know, with just a couple of Australia-sized planets. cratons, they called them, protocontinents. So those, we went through these snowball earth phases. And if it wasn't for the fact that we had kind of an active plate tectonics, which had a lot of volcanism on it, we could have been locked in that forever.
Like once you get into a snowball state, a planet can be trapped there forever, which is, you know, maybe you already had life form, but then because it's so cold, you may never get anything more than just microbes, right?
So what plate tectonics does, because it fosters more volcanism, is that you're going to get carbon dioxide pumped into the atmosphere, which warms the planet up and gets you out of the snowball Earth phase. But even more, there's even more really important things.
I just finished a paper where we were looking at something called the hard steps model, which is this model that's been out there for a long time that purports to say intelligent life in the universe will be really rare. And it made all these assumptions about the Earth's history, particularly the history of life and the history of the planet, or have nothing to do with each other.
And it turns out, as I was doing the reading for this, that Earth probably early on had a more mild form of plate tectonics. And then somewhere about a billion years ago, it ramped up. And that ramping up changed everything on the planet. Because here's a funny thing. The Earth used to be flat. You know what I mean by that, right? So all the flat earthers out there can get excited for one sec.
Clip it. Yeah.
what i mean by that is that there really weren't many mountain ranges right the beginning of i think the term is orogenesis mountain building the true himalayan style giant mountains didn't happen until this more robust form of plate tectonics where the plates are really being driven around the planet and that is when you get the crusts hitting each other and they start pushing you know into these himalayan style mountains the weathering of that
The erosion of that puts huge amounts of nutrients, things that microbes want to use, into the oceans and then what we call the net primary productivity, the bottom of the food chain, how much sugars they are producing, how much photosynthesis they're doing. shot up by a factor of almost a thousand, right?
So the fact that you had plate tectonics supercharged evolution in some sense, you know, like we're not exactly sure how it happened, but it's clear that the amount of life, the amount of living activity that was happening really got a boost from the fact that suddenly there was this new vigorous form of plate tectonics.
Yeah, that's actually really true because what happens is if you look at the history of life, that's a really, you know, it's an excellent point you're bringing up. If you look at the history of life on earth, we get, uh, you know, a biogenesis somewhere around at least 3.8 billion years ago. And that's the first microbes. They kind of take over enough that they really do.
You get a biosphere, you get a biosphere that is actively changing the planet. But then you go through this period they call the boring billion where like it's a billion years and it's just microbes. Nothing's happening. It's just microbes. I mean, microbes are doing amazing things. They're inventing fermentation. Thank you very much. We appreciate that.
But it's not until sort of you get probably these continents slamming into each other. You really get the beginning of continents forming and driving changes. that evolution has to respond to, that on a planetary scale, this turmoil, this chaos is creating new niches as well as closing other ones. And biology, evolution has to respond to that.
And somewhere around there is when you get the Cambrian explosion, is when suddenly every body plan, evolution goes on an orgy, essentially. So yeah, it does look like that chaos or that turmoil was actually very helpful to evolution.
Well, I think what's... I'm not sure if that's true. I don't know if it needs to be like an almost extinction event, right? Because it's certainly true that we have gone through... almost extinction events where we've had five mass extinctions. But you don't necessarily see that there was this giant evolutionary leap happening after those.
With the comet impact, the KT boundary, certainly lots of niches opened up And that's why we're here, right? Because, you know, our ancestors were just little basically rodents, rats living under the footsteps of the dinosaurs. And it was that common impact that opened the route for us. But it wasn't, I mean, that still took another, you know, 65 million years.
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