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.
Trend
recordings per month · last 12 monthsNo recordings in the last 12 months.Older appearances are listed below; set an alert to hear about the next one.
Appearances
Yeah, that's the question, right? 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. So 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, you know, 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 we are. life is. The one answer I can tell you, which was an important part of the problem, is how many planets are there, right?
And just like people have been arguing about the existence of life elsewhere for 2,500 years, people have been arguing about planets for the exact same amount of time, right? You can see Aristotle yelling at Democritus about this. You can see they had very wildly different opinions about how common planets were going to be and how unique Earth was. And that question got answered, right?
Which is pretty remarkable that in a lifetime you can have a 2,500-year-old question. The answer is they're everywhere. There are planets everywhere. And it was possible that planets were really rare. We didn't really understand how planets formed. And so if you go back to, say, the turn of the 20th century –
There was a theory that said planets formed when two stars passed by each other closely and then material was gravitationally squeezed out. In which case, those kinds of collisions are so rare that you would expect one in a trillion stars to have planets. Instead, every star in the night sky has planets.
That actually we're able to do now. There is, you can run simulations of the formation of planetary system. So if you run the simulation, really where you wanna start is a cloud of gas, these giant interstellar clouds of gas that may have a million times the mass of the sun in them. And so you run a simulation of that. It's turbulent. The gas is roiling and tumbling.
And every now and then you get a place where the gas is dense enough that gravity gets hold of it and it can pull it downward. So you'll start to form a protostar. And a protostar is basically the young star of this ball of gas where nuclear reactions are getting started. But it's also a disk. So as material falls inward, because everything's rotating,
As it falls inward, it'll spin up and then it'll form a disc. Material will collect in what's called an accretion disc or a protoplanetary disc. And you can simulate all of that. Once you get into the disk itself and you wanna do planets, things get a little bit more complicated, because the physics gets more complicated.
Now you gotta start worrying about dust, because actually dust, which is just, dust is the wrong word, it's smoke, really. These are the tiniest bits of solids. They will coagulate in the disk to form pebbles, right? And then the pebbles will collide to form rocks, and then the rocks will form boulders, et cetera, et cetera. That process is super complicated.
But we've been able to simulate enough of it to begin to get a handle on how planets form, how you accrete enough material to get the first proto-planets or planetary embryos, as we call them. And then the next step is those things start slamming into each other. to form, you know, planetary-sized bodies. And then the planetary bodies slam into each other.
Earth, the moon came about because there was a Mars-sized body that slammed into the earth and basically blew off all the material that then eventually formed the moon.
Yeah, so the temperature of the material in the disk depends on how far away you are from the star. So it decreases, right? And so there's a really interesting point. So like, you know, close to the star, temperatures are really high. And the only thing that can condense, that can kind of freeze out, is going to be stuff like metals.
So that's why you find mercury is this giant ball of iron, basically. Yeah. And then as you go further out stuff, you know, the gas gets cooler and now you can start getting things like water to freeze, right? So there's something we call the snow line, which is somewhere in our solar system out around between Mars and Jupiter.
And that's the reason why the giant planets in our solar system, Jupiter, Saturn, Uranus, and Neptune all have huge amounts of ice in them or water and ice. Actually, Jupiter and Saturn don't have so much, but the moons do. The
Yeah, I think we can. I think we're learning how to do that now. So, you know, one part is like trying to just figure out how to how planets form themselves and doing the simulations like that, that cascade from dust grains up to planetary embryos. That's hard to simulate because it's both you got to do both the gas and you got to do the dust and the dust colliding and all that physics.
Um, once you get up to a planet sized body, then, you know, you kind of have to switch over to almost like a different kind of simulation. They're often what you're doing is you're doing, you know, sort of, you're assuming the planet is this sort of spherical ball. And then you're doing what, you know, like a one D a radial calculation. And you're just asking like, all right.
How is this thing going to, what is the structure of it going to be? Like, am I going to have a solid iron core or am I going to get a solid iron core with that liquid iron core out around it like we have on Earth? And then you get, you know, a silicate, kind of a rocky mantle and then a crust.
All of those details, those are kind of beyond being able to do full 3D simulations from ab initio, from scratch. We're not there yet. How important are those details, like the crust and the atmosphere, do you think? Hugely important. So I'm part of a collaboration at the University of Rochester where we're using the giant laser. Literally, this is called the Laboratory for Laser Energetics.
We got a huge grant from the NSF to use that laser to, like, slam tiny pieces of silica to understand what the conditions are like at, you know, the center of the earth, or even more importantly, the center of super earths. Like the most common, this is what's wild. The most common kind of planet in the universe we don't have in our solar system. Which is amazing, right?
So we've been able to study enough or observe enough planets now to get a census. You know, we pretty, you know, we kind of have an idea of what, who's average, who's weird. And our solar system's weird because the average planet has a mass between somewhere between a few times the mass of the Earth. to maybe, you know, 10 times the mass of the earth.
Showing 1–20 of 594 · page 1 of 30
Next →