Distant Aliens & Space Dinosaurs with Lisa Kaltenegger
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So Matt, after that conversation, I'm ready for life to be discovered on exoplanets like tomorrow. I mean, I'm going to need lunch first, and then I think we're good to go, right? I'm excited. I'll feed you, and then we'll learn about life in the universe. No, just a salad. Just a salad. And then, you know, we've been learning a lot about methane and stuff. I don't want anything too big. Okay. All right. Me too. Looking forward to this. Life in the universe. Finally, with the methods, tools, and tactics to figure it out. And the James Webb Telescope. That's it.

lending its hand. Coming up on StarTalk. Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk.

Will deGrasse Tyson here, your personal astrophysicist. I got with me as today's co-host, Matt Kirshen. Matt! Hey! And I have you in person. I know, I know. It's been so long since I saw you not through a screen. Yeah, like it's real. You can put post-it notes on my actual face rather than just covering it on the screen like normal. Oh, is that what I do? I imagine. Well, welcome to town. Welcome to my office.

It's lovely to be back. At the Hayden Planetarium of the American Museum of Natural History. I mean, that's always exciting. It's fun to come to work. Does it get old? I hope it doesn't ever get old, the fact that you walk through the Natural History Museum to get to work. It never gets old when I pass little children seeing exhibits for the first time. And I just remember when I was a kid with that same experience. Plus, if you come through at night...

Yeah. Don't tell anybody, but all the animals come to life. I've heard the rumors. I've heard the rumors. It's really true. So today is going to be a Cosmic Queries. Great. And it's on, I think, everybody's favorite subject, the search for life in the universe.

Now, most people just talk about it. But some people have invested research time trying to figure this out. Some people have actual expertise in it rather than just... Maybe that's what I'm actually saying here. Yeah, rather than people like me just, you know, looking up at night and going, ah, there's got to be something, right? So I have with me Lisa Kautenegger. Did I say your name correctly? Kautenegger. Kautenegger.

Perfect. And it's so much fun to be here. And Neil, I have to tell you, even so, it's the small kids that do the wonder when I walk through those doors. I'm back as being the small kid. You're a kid again. And I do want to know if at night the dinosaurs come alive because I'm here. We're just going to record until night because I want to see that. You don't want to leave. No, no way. So you, I have your brilliant...

Background here. First, you're an astrophysicist, but more importantly, you're an astrobiologist. So there's a whole bio side of you. And any biology I know, it's like I have to pick it up on the side. But here is centerline with you. And you're Associate Professor of Astronomy at Cornell University.

Who else was at Cornell? Somebody else. I don't know. Was there anyone? Rhymes with Fagan. Is there? Reagan. Oh, oh, oh. Let me just cut in. Is there someone involved in like communication as well as research? Well, you know. Anyone who wrote books? There's this cool office on the third floor where Mrs. Kaltenegger is sitting right now, but it was the office that rhymed with Fagan. Oh. So it's who got Carl Sagan's office? There's an answer to that. Me, me, me.

- Wow. So I was- - No pressure. - I was in that office 50 years ago. - Wow. - 49 years ago, I was in that office. - You know what? If you come back and be in that office, just think about what's gonna happen then. - Oh. - When the first one- - What kind of sorcery will you be? So what you have to do is get your office set so that we can reprise what he did, okay? I'm in his office and he reached back, did a no look reach,

behind him. No Look Reach pulled out

a book that was one of the books he wrote and then handed it to me, signed it to me. So you're going to have all the books that you wrote on that shelf. And then my shelves are like old hickory, like I have like books piles. So I'm going to just pull one and then the whole thing's going to come towards you. Yeah, I feel like if I tried that, I'd somehow pull the bookshelf onto me. You are director of the Carl Sagan Institute. Absolutely. And like I said, the answer to the question, who got Carl Sagan's office and your research interests, you're, you,

You model habitable worlds. And so the great thing right now is we know more than 5,600 worlds around other stars, other suns, if you want. You know, of course, their name is not sun, but it's cool when you look up and you know that around every fifth one, there's a planet that's at the right distance, so not too hot, not too cold, and a rock so small enough

And so it could potentially be a habitat, as you said. And so we live in this time where with the James Webb Space Telescope, big telescope we put into space, for the first time we can catch enough light to figure it out. So why does the light tell you that there might be life?

So the light is a cosmic traveler. And the great thing about it is it's actually encoded information in it. That's how astronomers know how the universe works. Yes, we don't know anything without that, right? That's very true if it's dark. You can't go there. You can't put it in a Petri dish. Even so, I do have to say the engineers should do a bit more work, right? I've seen this on Star Trek and Star Wars. Engineers do enough for us. Now she wants them to go to the stars as well. You heard it here first. Engineers, you're all lazy. Every engineer. I'm just

saying abandon the other stuff all pulled together and make me an enterprise right I would like to go to these cool stars we found okay do you want to upset this fine scientist engineers can't satisfy us at all okay but you know what the thing is like I'm even doing the blinky eyes if somebody gets me a starship enterprise I will do that I can't do that okay

If that's what it takes. All right. So in the light, what's encoded there that is of value to you? So basically, when you have light, what we do as astronomers is called spectroscopy. We split up in its colors and we figure out if all the energy gets to us or if some of the energy hit the molecule or atom before it got to me. And that's even so I can set foot. I cannot set foot on these planets yet.

I can actually figure out what's in the air of these other worlds. Okay, so because each molecule has its own characteristic absorbing pattern, right? Yeah, okay. Exactly. It's like a barcode. And if you think back to high school, like each chemical has a different structure. Like water, H2O, right, has an oxygen atom and two hydrogen ones. It looks a little bit like a triangle, nearly.

And oxygen, two oxygen atoms, looks different. So the energy that needs to hit it to make it swing and rotate needs to be different. And light carries energy. So which one's missing tells me, like a stamp and a passport, what chemical is in the air of this other world without me being able to get there. What's kind of nearly as cool as... So what are you specifically looking for? What things are you hoping to find or expecting to find?

So what we're looking for is when you look at the earth and try to figure out if there's life on the earth, the combination of oxygen and a reducing gas like methane,

tells you that something is producing oxygen methane in huge amounts. So reducing means you take an oxygen away from where it once was. Exactly. Reducing basically means it reacts with oxygen. And it steals it. It steals it. Absolutely. It's a good stealer. And so it makes CO2 and water. So if you see it together in the atmosphere of a planet, you need two sources that produce it.

And for methane, could be life, but also could be volcanoes. What you're saying is that the methane and the oxygen, when left alone, are unstable.

And they will disappear unless somebody is cranking it out continually. Or something is cranking it out. Exactly. Just love each other. Think about this. They love each other so much that they will actually dance and go and make CO2 and water. So by them being together in the atmosphere, you can actually figure out that that's a fingerprint of life as we know it. Oh, because if it still exists, if it isn't disappearing and you don't have a volcano that's causing it,

So for the methane, the volcano could do it. But for the oxygen with the methane, the oxygen needs life to do it in those big quantities. But if it's just oxygen, it's not enough. Because you could think about the long time, like our planet's been around for 4.55 billion years, right? So if you had one oxygen ever so often, let's say one oxygen atom a week, then it would build up. So you need the methane to grab it. Did you say one per week? Yeah.

If you had one or one per month, you're 4.5 billion years, right? You can accumulate it. This is why you need the methane. This is why it's key to have the reducing gas. Other than that, it could just build up and you wouldn't know where it comes from. Did you put all that in your book? I did. Alien Earths, the new science of planet hunting in the cosmos. Ooh. Ooh.

And so the cool thing that when I think about these alien worlds, like some of them could be like ours. So they could be habitats as we just talked about. Hence alien Earths, not just alien aliens. No, and there's an S at the end because the other way is also think about it that way. When you look at our own planet through time, you wouldn't be able to say you and the Earth if you were a time travel. So that doesn't work like Einstein's show. We can go back in time. But if you could...

you would not be able to figure out it's the Earth and probably not, you know, Statue of Liberty hands sticking out or something to tell you. Wait, the Statue of Liberty shows up in every science fiction movie. I know. So you know it'll be there. Yeah, so what will be their equivalent on other planets? Is this one of the things that you research? Like, if they don't have the same kind of like hominid shape to their bodies, like their Statue of Liberty would look weird to us. It would look normal to them. It could be like lobster with a claw sticking out. Yeah, but still holding a torch. Okay.

a claw holding a torch. Yeah, exactly. I figured it would still have a torch and a crown. But like it would be maybe two crowns. It depends on how many heads it has and how many. But I think the good thing is like thinking about it might be easier to spot if it's like three legs or five legs. We only have one arm. Like how did they do it? Like this one arm stuck out. Wait, wait. So Lisa, how biased are you? How biased are we? I think we as scientists and you know, Neil, you also were thinking about life in the universe at one point, right?

So I think we're biased, but in a good way, because we have to be ultra conservative to tell you that we found life. We don't want to just make it up. And so what we do is we look for something that we cannot explain other than with life.

and keep our eyes open for things that are interesting, weird, and unexplained in terms of chemical makeup of a planet or some kind of features like art, space art that blocks out some part of the starlight. So lots of ideas are coming in, but we have to be conservative to find it for sure. And then we have to have an open mind for something we don't know what to expect yet.

And this is all because we can't actually see the surface of the planet to see if there are cities or people or whatever. So you got to do this secondary way to get in on there. Absolutely. But what's really cool is the next generation of telescopes that we're planning right now, the Habit of World Observer, for example, supposed to be really big so that you actually can block out the star's light, see the tiny, tiny planet next to it and catch the light from the surface.

And thus, you know that you said about the biology and my name, right? And my professional description. I actually have a bio lab where we go grow life in all the different colors from all different parts of the world, like deserts, like ice fields. Did she just say she creates life in her...

She grows it. She grows it. She grows it. I'm not... No, no, no, no, no. I'm just verifying. I mean, you've never seen my kitchen, but we've been growing life there for a while as well. I'm not proud of it. It's a bottom shelf of the refrigerator. Yeah, yeah. There's some different colors. Right, right, right, Matt. So if you have any colorful ones, send them our way. All right. Give me an address. Give me a mailing address. Can I ask you a question?

Someone like your equivalent on a different planet, on a different star, had a telescope pointing at Earth. What would be the markers of life that they would see from us? That's exactly the question I had about two years ago. And with an amazing person here at the American Museum of Natural History, Jackie Faharty, we actually went to figure that out because we know where the stars are. There's an amazing mission called Gaia that's up there right now that is having a look where all the stars around us are. And we're like, where would we be?

We be the aliens. And so we figured out that if you just have our level of technology, that means you need to have the planet go in front of the hot star so you see the star ever so slightly being less bright. For the Earth, that would be once a year for 12.8 hours.

Then there are within 300 light years, so light from there to us and the other way around about 300 years, there are 2,000 star systems where we could be the alien and people could be wondering...

Hopefully they're not bad aliens there. We're pretty bad aliens, I think. They won't think there's life around us unless they can see the Statue of Liberty sticking out of something. I'm strongly hoping that they also figured out that the gas combination will work because that lets you say that there's life on our planet for about two billion years. And that's how I got started in the field because I was part of the design team to build such a telescope to try to find other life.

on other worlds. And we were looking for 20%, 21% oxygen deaths right now, modern Earth. And I was like, but the Earth changed, right? And then people said like, well, yeah, if you think that's important to figure out, do it yourself. And I was like very young and naive. I was like, oh, you can do this.

Then I figured out how hard it was to do so nobody had done it before. And this is why we figured out it was 2 billion years. And you know, 4.55 billion years of history on the Earth. But for half of it, think about it, for the 24-hour clock, since lunchtime, you can actually spot signs of life on the Earth.

And so in a way, the news is out of the bag if they just figured out our level of intelligence. And I'm having high hopes that there's more out there than just our level. That assumes we are intelligent at all. Exactly. We redefine it. But let me lay some physics on what you just said. I think technically, if you want to be physics precise, it's not that methane and oxygen are signs of life. It's that methane and oxygen are signs of something out of equilibrium. And life itself is out of equilibrium.

Maybe we need to be more creative about other things that could be out of equilibrium other than life. Is anyone thinking that way? What's really fascinating, and that was where like in '65, they started out with this combination of oxygen and methane, right? So it's like old school science. '65, you mean? 1965, sorry, 1965. That's the Miller-Urey experiment.

Went around that time too. But the idea was then they said, well, it's just disequilibrium. But then we actually figured out that geology is super good in making disequilibrium. And sometimes life actually brings an atmosphere chemistry back to equilibrium.

So there's only some very specific pair of gases that in disequilibrium would actually only be explainable by life. And so that's like new, right? Because you'd say like, okay, 1965, they figured it out, right? We've done stuff since then. Even so, we haven't found life yet. But it's fascinating. This search tells us so much more about our planet too and how it works and how life works. So before we go to Q&A, because this is a Cosmic Queries,

One question before we hand it over to you, Matt. I'm in. I'm ready. You collected the questions from our Patreon members. And this is, unsurprisingly, this may not be a shock, but this was one that brought in a lot of questions. So I'm going to try and get through as many as I can. Of course it would. This is a biggie. I'm excited. Okay, so let me just ask, what is life?

Oh, such a good question and a whole chapter in the book and no answer. Oh, is it blank pages after the what is life question? It's just a shrug. It's just a picture of shoulders going up. It's just you shrugging, yes? It's really, really great because as an astronomer, I actually don't need to know what the basic tiny definition of what life is because I need a biosphere that changes my whole planet for it to spot it somewhere else around another star. So in a way...

I've put all the knowledge we have together, you know, that it basically can evolve, that it's during evolution, that it has information content and so on and so forth. And that's an entity that's encapsulated. So I put everything together from biology, Nobel Prize winners and other people I talked to. That one I didn't talk to. I actually read his book.

But I talked to the other people who do biology in the Carl Sagan Institute, and they're like, yes, no, no, yes. That's a good sign. It means it's a vibrant field. It's a vibrant field. So I distilled everything I know, and then I did put a blank page for your work here. Did you? Oh my gosh! We were just joking.

I'm going to be honest with you. I don't think my version of my work here is going to be much help to the field, but some other people might. Some other readers of your book might take that baton and run further than I can. I think mine's more likely to be a shopping list. Right, here we go. And the first page is pretty cool too because it has alien wannabes. Oh yeah, life on Earth that would... If you would show it to me, right, without DNA testing, I would be like, oh my God. And of course, here's the tardigrade.

Oh, yeah. Stuff on Earth that looks alien, basically, is what that is. And that survives things that it kind of, you don't know why it survives. We know it's desiccation for the tardigrades, but, you know, if you would sell it as like an alien, you'd get pretty far until... Desiccation means you remove the water. You remove the water. And leave it for dead.

Yes. And it just doesn't care. And it still has the ability to re… So here's the page where you've drawn your own planets and life and things. I gave you a couple of planets, but you can do all your own ideas here. Very thoughtful. See, this is what I want in a science book. I want facts and information, but I also want doodling space. Exactly, me too. And the really great thing is like when you write your own book, you can do what you want to a certain extent if you can sell it. That's right. That's right.

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Hey, Green Gobbler here. So you've got a clogged drain in your batch room. Water in the sink's overstaying its welcome. You're spitting today's toothpaste on top of yesterday's toothpaste. You hoped that it'd go away. Yeah, clogs don't just go away. I make 'em go away. I'm Green Gobbler, the only clog dissolver you need.

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So Matt, bring it on. Given that you've just brought up sea creatures and other creatures on Earth that look alien, Craig Cordwell from the UK, from my home planet, says... Wait, it's my home planet too.

The UK is not a planet unto itself. I was there last week. We have an ego. We have an ego there. You might think that, but not in New York City are you going to get away with saying that. Okay, go on. So Craig asks, how possible is it that life has landed on Earth from a meteorite and has just become another animal? He says, I'm pointing at the octopus here, but not exclusively. Oh, I'd love that. I love the show. Octopus don't look like nothing else on Earth. Eh.

And I've seen them land in the movie Arrival. So, you know, they kind of look octopus-likey. Octopus-y, right, right. But the cool thing about this, if you think about where they could come from and people think about Mars or other planets, actually, the Earth had the best bet. So,

so far because it had watered the longest on a rocky surface. So the question is more like if we were to find life on Mars, maybe we're going to find out they're actually Earthlings that became Martlings. But of course, it sounds cooler if we might be Marslings or some other things would be. Did you say the word Marslings?

Well, I did hypothesize. Didn't we invent a word for that already? Martian? There's a movie called Martian. I know, I know. Nobody calls Matt Damon Marsling. Well, that's why you're the scientoid. This is the key thing that we haven't found life on Mars, so I can't say Martian, so I say Marsling, just as a hypothesis. Okay. But the cool thing is like, if there were kind of different life, we would find it.

find out if we do our science-y thing, where we basically check everything and see if the DNA is made out of exactly like everybody else's DNA, chemistry-wise, right? Then you don't get away with calling it aliens, because for an alien creature, you'd hope that at least one chemical pair is going to be different to tell us. Right. Because it seems quite unlikely that even if life's on another world, what I hope,

that it is exactly the same chemistry it will use. Why is that unlikely when if you talk to geologists, they see similar minerals on other planets? Absolutely. Why do they get to have the same rock formation process, but you...

are not going to recognize that maybe biology is universal. I think biology is universal. I didn't want to say that. What I mean was like carbon scaffolding and water are probably really, really good basis for life. But what nuclear pairs you could have taken for the DNA, you have so many options or for proteins.

And there aren't so many options to make minerals. Oh, gotcha. And so I think this is why, because it's going to be so weird when, for example, we'd find it on Mars, right? Would it have been a hitchhiker we brought if it looked exactly like the Earth? Or is it life doing the exact same thing and a different environment down to the tiniest atom? I bet everyone would bet on the hitchhiker. Well...

This is why we're going to the icy moons and hopefully just fly through the plumes of Jupiter and Saturn so that we don't contaminate those pristine environments. And this is why it's the whole departments of NASA whose job it is to make sure we don't do that contamination, right? Exactly. It's a job, but it's so hard to do because life is very hard to kill. Good thing. It's a good thing. It's a good thing. Yeah.

Yeah, you should say that with like a… She's trying it. I've tried to kill her so frustratedly. I've got so many hammers. I've tried fire. There's nothing. That's what she does most of the time in her lab. The coolest thing is actually if you think about life on the Earth, you would actually have to melt our planet to about 10 kilometers down to actually eliminate life because there's life down to about 10 kilometers. That deep? That deep.

And so if you just sterilize... She's thought about how to get rid of life on Earth. This worries me. Does it worry you, Matt? How do we autoclave Earth? Here's how you get rid of life on Earth. Melt it down to 10 kilometers. Because we now know there are these extremophiles, right, that can survive in volcanic gases. Or tardigrades, right? Yeah. So you can't just boil Earth for...

Two minutes. I think about it as more hopeful because even if we were stupid enough, and I hope we're not, to actually destroy all of ourselves, destroying life is luckily so much harder than some other kind of bug might actually make it to the stars if we can make it. Plus, if you look at the extinction...

record, maybe we should be amazed we're all still here. There's a 90% extinction episode, the PT extinction, Permian Triassic, and then there's the famous one, the KT extinction. We lost 70% of species. I mean, the universe has been trying to kill life on Earth for years. And here we are doing a podcast. I remember

I really think this cool wonder that we hear and then we can actually figure out the secrets of the stars, right? We can do that. I actually think we should give this much more wonder and credit and thus, like kids seeing exhibitions for the first time, look at the stars anew. We figure out what they're like. The wonder and the majesty of it all.

So Torsten Diekhoff from Berlin says, "It took evolution quite a while to develop multicellular life on Earth. How likely is it that most planets are populated only by bacteria or similarly simple life forms?" Also great question. So this 2 billion years of oxygen and methane combination gives you a range of life.

What we don't know is how fast evolution could be on another world because we have only a sample of one, ours. But we think with more and more oxygen you get more and more complex life. Just think dinosaurs. There was more oxygen in the air actually when the dinosaurs were around, thus big creatures.

And so... Right now we're at 20, 21%. We're 21. What was it back then? We think 30 to 32. And so the coolest thing is like Jurassic Park worlds would actually be easier to spot than us. And so we published this. It was pretty funny. And then the headlines were like, alien dinosaurs. Like, whoa, whoa, we didn't talk about alien dinosaurs.

dinosaurs we just said? You can't put those two words in a title and have the press properly interpret it. But having said that, I saw it differently because if we now get everybody who loves dinosaurs to also love exoplanets, they have to if we're looking for alien dinosaurs, right? That gives us 100% of all kids. And I think that's exactly what we need to get to the stars.

I feel like we're stealing them from the anthropologists and the paleontologists, but I'm okay with that. Wouldn't they learn so much more if they had other dinosaurs on other planets? Yes, they would. See? It's just like we're helping out. Yeah. I mean, that is a way to get kids into science. Kids love space. Kids love dinosaurs. That's true.

Dinosaurs in space. There it is. And then if we tell them that you can go and talk to comedians who do funny things and be on the air and say, hi, mom, right? You know, what else is there that they would want? Maybe these superpowers. But you know, if you were on one of these other moons like Titan, because it has so much less gravity, but a dense atmosphere, you could flap your wings and you could actually fly on Titan. You couldn't breathe.

But you could fly. Yeah, you suffocate. But other than that, everything is fine. It'd be easy to fly, you're saying. You'd have a great 60 seconds or so as you chokingly fly in a panic. You could also come with a spacesuit. I'm not saying you can't do that. So what's the gravity on Titan then? It's just much less than here. Yeah.

Maybe it's a third. Moon is one-sixth Earth. So it'll be no more than half. Yeah. For sure. I think it's somewhere around a quarter, yeah. Sure. What do you weigh here on Earth? Pounds, dude. This is America. I have no clue about the pounds. 120? Yeah. So on the moon, you'd weigh 20 pounds. Just think about how high you could jump. And thus, we have all the kids back. We have superpowers we can give them. Damn, you want to give them superpowers, dinosaurs, and space. What more do you want?

Be kind to your fellow scientists. It does look fun bouncing around on the moon. I mean, that feels like... The funny part is like when you see the astronauts skipping, right? That's what I show my students when I teach. I'm like, look, this is real life skills. If you ever find yourself on the moon, you know that you have to skip.

And skipping, kids stop skipping like in middle school. Yeah, you shouldn't do that because you might find yourself on the moon at one point. Yeah, do they have to have skipping classes in NASA in training? I think they do. They do skip underwater. Is it part of selection? I don't know that. Neil, do you know that? Have you ever tried out for an astronaut? No, the underwater is just for zero G, not for low G.

Right, but did you ever try out for the astronaut program and actually try to figure out if you had to skip? No, no, I never did that. I never did that either. So, Matt, you have to go and become our token astronaut to figure that one out. I mean, I think I'm still a good skipper. I think I can still skip to a decent level. All right. But you will have to do it for the ESA, right? The European Space Agencies who will have to figure out about the American system. Well, how does it work? Because I'm on my way to getting citizenship, so I might be able to... Ooh, do both. Can I straddle both? U.S. citizenship. Can I get the two patches? Okay.

Why not? Why not? Yeah.

Science is international, so that must work too. Invite us to the launch. All right. It's a deal. You heard it here first. So there's a couple of questions about different types of life form and different environments. So Victor Ray Rutledge from Texas says, can there be entities, say life forms, which exist outside of any planetary boundaries? And then Jono from Iowa also says, what are the extremes of environmental conditions that we think life could exist in and we look for across the galaxy? I'd like that. So that would include planetary moons.

Maybe asteroids, comets, or just free-floating in space. Are these legit places? I think it's really great. So the first ones are absolutely legit places. So there's no reason a moon couldn't be a habitat. Or maybe even an asteroid, even though they're there, becomes a bit tricky because it gets really cold. So you have to dig down deep. And in a moon and a planet, you have residual heat from being actually formed. So you could do that. Wait, so the moon doesn't have heat...

left over from being formed but earth does right right earth style sorry so if you have a moon down under like the mid-ocean ridge and all these places exactly and the other moons in our solar system around the giant planets they are actually being molded so the other moons actually tack on them as well as jupiter or in the other system saturn and so there's tidal heat that gets generated so they actually get warm and this is why we have oceans

We have tides on Earth that move in and out, and we credit the sun and moon for that. So you're saying we have tides on moons of Jupiter. And what effect does that have on the… Absolutely. So we have tides on moons of Jupiter. And so what it does is basically we have these ice balls because it's so far away from the sun. Right, it's outside the Goldilocks zone. It's outside of the Goldilocks zone. But because of this pulling and pushing that actually deforms those moons, there's heat.

that melts the ice under the ice shell on top. And so we knew those ice shells actually swimming in liquid oceans. And so this is where we had hopes that maybe those oceans could also have kind of life. And so this is what you can do. No shortage of life in our oceans. No. That's a sensible thought. But it's a very different ocean. So this is why we're sending things there to investigate.

Oh, because it's much smaller and it gets like bent out of shape. And hopefully the bent out of shape has been since forever. But for some of the moons, they are a little bit smaller, like Enceladus that goes around Saturn.

And so it's a very not so deep ocean, but we think it has been around for millions of years. But the question is, has it been around for billions of years? And how long do you need an ocean to get life? And so I completely hijacked that question. So yes, life actually has some boundaries, as we know. It's when you destroy the cell walls.

And when you make it so hot or irradiated so much that everything breaks down, the structure that basically lets you concentrate chemistry in the inner part of a cell. I like the way you're saying that. So, I do know that molecules are held together by a certain binding energy. And if...

exterior to the molecule, there's more energy than that available. Just bust up the molecule. Exactly. And we are complex molecules. So you don't want to get busted up. You definitely don't want to get busted up. And it's actually even earlier because you need the cell walls because those allow you to get some chemistry in and some out.

And so if you were swimming in a huge ocean, one of the key problems you have is to concentrate the chemistry enough to get something like DNA and RNA started because you need concentration for that. Because you need the frequency of them bouncing into each other. Exactly. And the ocean is vast. And if there's like a couple of molecules, when are they ever going to meet, right?

And the other thing is like when it gets too cold, we think these reactions are starting to be so slow that it might take so long for any of them to take place. So there are some limits on life.

But so far, we think you need at least for starters, a rocky surface and some water where you can concentrate the chemistry and make these kind of vesicles that become cells. And then wherever you find those conditions, hopefully... But one of those questions was, we went how many...

Three and a half billion years with single-celled life? Is that somewhere around there, right? Absolutely. And the key point is that… That's a long time. That's a very long time, but there's two good things. So, there are stars that are older than us, and planets are as old as their stars. There's a star that's older. Well, that was older than the Earth is now when the Earth formed, and it has planets. But also, we have no idea what sets the evolutionary clock.

And so it could be faster evolution or slower evolution in other worlds. All I'm saying is, it seems to me, Lisa, that if Earth went three and a half billion years with single-celled life,

it could easily have gone another three and a half billion years. And this is why this lively discussion is so helpful in science, where people actually are now coming to the conclusion, or at least that's the best explanation we have right now, is that if you have enough energy available, and that was the oxygen content in our air, then you will make more and more complex life. And it's not completely done yet, but that's the best explanation we have for now. So get oxygen. So if you sneak some oxygen in early enough...

we might have had our explosion of complex life sooner in the timeline of the Earth. That's basically what the biologists are telling me. And so at that point, because I'm an astrophysicist, even an astrobiology-leaning one, my knowledge gets a little bit less complete. So I talk to people. But it kind of makes sense. If you had energy available that life could easily use, you could become more complex. So the life becomes...

-Opportunistic. -Absolutely. Opportunistic is, I think, a great word for life. So there's a kind of related question about the environment from Kevin Vale from Chester, New Hampshire, who says, "I've always wondered how massive of a rocky-type planet would carbon-based life still be possible? How much higher or lower gravity might affect life?" Ooh.

And so that's a great question. So generally, gravity should mostly affect the structure. Let's assume everything's equal. You have a rocky solid surface and you have some water. So then gravity affects your structure. You need enough pressure on top of your ocean not to evaporate the whole thing, right? So you need that. So chemically, what you're saying is

If there's just vacuum above the water, there'd be nothing to keep the water in its liquid state. Exactly. You need the pressure of the air in order to maintain that. Completely right. My in-laws live in Colorado. It's high altitude. Trying to boil something. Yeah, water boils off pretty quickly. You dry out very quickly. And that's a fraction of a vacuum. Right, right. Or you could have an ice layer like in the icy moons, right? That basically keeps your water below protected.

And so how small can you get? As small as you allow me to have liquid water on a rocky surface. And so those moons that get tidally heated, actually from the first principle without the tidally heating, they would be too small because everything would be frozen and cold.

But because they're tidally heated and physics works in the whole cosmos, you basically get this additional liquid water. So what's too small depends on the circumstances. Do you get pulled and pushed from your neighboring moons? Yes or no.

And so we're still learning the limits. But at one point, when it becomes so incredibly big, when it forms, it will actually grab onto all the gas that's around it and it will become one of these big planets like Jupiter or Saturn. And so at that point, we don't know how you could have liquid water with a rock interface where it's not super critical liquid water because there's so much pressure on it and so hot. You make an interesting point. So the more massive the planet is,

the more likely it would have retained gases that in Earth's history or Venus' history or Mars' history would have been long lost into space. Absolutely. So when we think about this, really it's like, why does the planet have an atmosphere and it's not the whole story? Then it's really the pull of gravity that the planet has versus the escape velocity, how fast you need to beat the molecules in the air. So there's no such thing as a jumbo rocky planet.

With only rocks? We don't think so. And so that's the really interesting thing, again, with the James Webb Space Telescope, because what we found, most of the planets, I said thousands of planets, right? One out of five, maybe like ours, 200 billion stars in our galaxy alone. Billions and billions of possibilities. Even so, of course, he never said it. But what's really interesting here is that the most common planets...

are some we don't have. They are bigger than the Earth and smaller than Neptune. So these super-Earths, great name, whether they're better is absolutely not clear. How are they like? This is what we're now figuring out. We don't know from first principles. We have some ideas, but the James Webb Space Telescope lets us look and confirm those.

You did say billions and billions. The man wrote a book called Billions and Billions. I know, after everybody kept saying it. And then he went on to the show, right? And said, okay, now I say it officially. Do you know who first said billions and billions? Who did? It was Johnny Carson. Johnny Carson, right? From The Tonight Show. But he basically interpreted it as saying that Sagan said it, right? Yeah, he was imitating Carl Sagan in an exaggerated way. He knew he said billions and billions.

And he said it so in a fun way. You got to double up on it. Plus, there was a cartoon where Carl Sagan as a child says, look at all the stars. There must be hundreds and hundreds of them. Perfect. It's part of pop culture. In 1976, Carl Sagan published a paper with Ed Saul Peter.

speculating on life in Jupiter's atmosphere. Until now, you've only been talking about rocky surfaces. And he was imagining predator-prey, a combination of life forms that could sustain themselves without any care at all about the surface of anything, like balloons that had buoyancy, these flying creatures living off the temperature gradients within the atmosphere. Is there much thought still given to that idea?

I love that paper just because it shows the creativity that you need at the edge of the forefront of science.

But we have learned more and more about the origin of life since then. Luckily, science always learns. It was 50 years ago. It was 50 years ago, and it was a visionary paper. But what we've learned so far is that you need a rocky surface and some kind of water to get this chemistry going, to start it. To start it. You can't just have molecules come together and convecting air cells. The chances that they're going to stick to each other and make it

kind of cell are just so small even if you give it 4.5 billion years. But having said that, once we have such floaty things, we could always bring them to Jupiter and reenact Carl Sagan and Salpeter's amazing paper. That'll be our atmospheric zoo. There's some kid watching that. That's your task. That's your... 50 years from now, that's going to be your job. That sounds great. I want to be a zookeeper there too. ... ...

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Hear that? That's what cooked when you order juicy beef sounds like. The steaming hug of two slices of melted cheese, the crunch of tangy pickles and sliced onions, all topped with a toasted sesame seed bun. That's the sound of a McDonald's quarter pounder with cheese. First Beef at participating U.S. McDonald's. Excludes Alaska, Hawaii, and U.S. territories.

So what else you got? Well, we've been dancing around this question and this idea a little bit. So let's just ask it directly. This is from Gavin Traber from Sacramento, soon to be Dr. Gavin Traber, RNA, biochemistry, and molecular medicine. Ooh, go for it. And...

Gavin wants to know, do you think the origins of human life on Earth, or at least the basic building blocks such as amino acids, came from the stars already formed from elsewhere, or were they originally synthesized in a prebiotic Earth? So let me offer a version of that question back at you, okay? You guys always talk the talk when the amino acids are discovered on meteorites being delivered from space. You talk the talk, okay?

But Earth is made of all these same ingredients. Why do we need any ingredients from space at all if the birth ingredients of Earth has all those ingredients

all by itself. I really think it's more the glamour from everything that comes from space. Because you can make the chemistry down here too, but it's kind of cool to find it on an asteroid or a meteorite or another moon, right? It's got a cool factor. I think it has a coolness factor. Is there even any way to necessarily know? Which one's which? Yeah, like how would we know whether this amino acid became... At that point, we need the TARDIS.

You, me, and Neil have to go in and then get back to that point. TARDIS as in Doctor Who's. In TARDIS, a Doctor Who's TARDIS. Yeah, the doctors. Not just to the right time, but to the right location. This is why I want the TARDIS, right? Because it gets you to where and when you want to be. Space and time. And figure out how life started here on the Earth. Then we could tell. I think I know the answer to this, though. Go ahead. I think. Many amino acids have a chirality to them where they are different in a mirror.

from what they are in real life. So there's a certain configuration of the atoms that is just not symmetric in a mirror. Am I right in thinking that one way is good and the other way is evil?

One has a goatee here. That's how we tell. That's how you know. One way is good and the other one is just blah. Like one is your favorite food and the other one is blah. So the amino acids that would have chirality on meteorites are 50-50. And all the ones on Earth are the left-handed or whatever is the handedness. So all life has only one handedness, but the ones from the meteorites have both. Exactly. But the key point is that

Did you need to bring them to the earth so life had enough to eat? So the theory would go that, you know, if we're starting out and we didn't have life yet, we probably had 50-50. And it's quite interesting that there are some researchers who say that it could have gone either way. Yeah. But life just picked one. And that's the one it picked.

And what's really fascinating too is that when we're trying to make life in the lab and we can't do that yet, that's the problem, right? We don't know how life started because we can't do it in the lab. And so, to all the amazing colleagues, because before that you said I don't like engineers. I love engineers. Married to one. But basically, just to say, it is really hard to make life in the lab. And what you would want to do is you would want to make it with a different chirality. So,

So you know you're making it from scratch. And that's so hard to do. But people are trying to do it. And then when the life escapes the lab, you can track. You know which ones to kill. We know which ones to kill. It's not going to kill you because you were blah, right? It doesn't want to eat you. You're not interested. It can't digest you. Exactly. It's a safety measure. But I bet if it's chasing you down the street, it won't know until after it's

your stomach that it couldn't digest you. That's evolution and we have like billions of people so hopefully just don't be the one that it eats first. First, right. So we have time for like one more. Okay well I like this question from Eduardo Lobato from Spain but living in Finland but asking the question in English.

And Eduardo says, does the discovery of dimethyl sulfide on planet K2-18b by the James Webb make us rethink how probable life is in other worlds? And also, what makes DMS a marker of life? So, what's really interesting, one supply… Let's back up for a minute. So, K2, that's in the Kepler's catalog. Is that right? K2-18b. Right. It's not like the other peak. Yeah.

Yeah, the other mountain. We've just discovered it. We've discovered life on that mountain. Yeah, it's a climber. It's a dead climber. He used to be alive. His name was Ben. He had feelings and family. Oh, no. Come on. Okay. Can we survive? That's his catalog ID. K2, keep going. A.

K2-18b. 18b, okay. So now tell me about this molecule. So basically it's DMS, dimethyl sulfur, and on the Earth, life makes it. But now we have these other planets, we were just saying these super-Earths and mini-Neptunes. We don't understand the geology, we don't understand the photochemistry. So even if we see gases that on the Earth in a chemistry like ours would actually indicate life, you have to be very careful not to misinterpret it.

And that specific case is interesting because it tells us something new about these weird worlds we don't have in our solar system. We definitely try to think about ways that life could be there. But if you have so much gravity, you would have kind of a supercritical ocean under a huge amount of hydrogen. And on the Earth, the bacteria that makes DMS needs light. And so there it would actually be dark. And so absolutely, we're thinking about this a lot. And you can deduce all of this?

from just the James Webb data. From the spectroscopy, from basically looking at the light. And so what's really important about these discoveries is that they make a thing. It feels almost voyeuristic. Yeah. I'm spying on you. Do these bacteria mind us? Well, this is the question, right? We haven't asked for the consent of spying on other potentially alien worlds, but we're doing it very kindly. No interaction. We're just looking. And then if we find something interesting…

- There's still probably a law against it. - I was about to say, but we don't know the laws there. So it's not just the engineers, it's also the lawyers who have to get up to speed. - Right, right, right. So it's intriguing. This planet is bigger than Earth, but not as big as Neptune. Is that right? - So it's bigger than ours, but not as big as Neptune. But the key point is it will be so different from the Earth that you shouldn't just go with the same conclusions when you find something that would indicate life on the Earth.

And that's where we're learning. The more interesting planets we find, the more patterns we will see, and the more we'll learn about geology, photochemistry, all these other worlds, what we just don't know because we never had one of those in our system. If it were an Earth-like planet, then you'd feel more confident. Oh my God, if it were an Earth-like planet, I'd be so much more excited about it. But if you have a mini Neptune with a huge hydrogen atmosphere, no light hitting a potential ocean, we don't even know if the ocean is there.

Then I'm just saying maybe intrigued, but not sold yet.

I like that. Intrigued but not sold. All right, we got to end on that note. That's a very hopeful note, I think. I think the wonder… A curiosity-stimulating note that you just ended on. I think what's really great is that we live in this time where for the first time we could figure out if we're alone or not and all of us get to live in it. So that wonder that we all bring to looking at the night sky… Childlike wonder. Childlike wonder. We could…

Point up, count to five, say one out of five might have another Earth. One out of five of the stars. Stars might host another Earth. But maybe in a couple of years, we could say, oh, that one.

That one shows signs of life. And then you realize that that one's actually just a plane flying over the edge. That shows signs of life too! It does have signs of life in it. Look at the Elon satellite that's going across, right. Oh my gosh, Lisa, thanks for coming to town. Thanks so much for having me. This was fun. And congratulations on the book, Alien Earths. You know what? Somebody called Neil deGrasse Tyson said it was good. It's on the back cover.

Whoa! Yeah! Who's that guy in that blurb? Hang on. Let me just see what that says there. Is that top blurb on the list? Of course, top. It's my duty if I'm asked to blurb a book to make the shortest blurb possible. It's still informative, and that usually ends up at the top. Lisa Kaltenegger's breezy narrative style invites you to experience with her the challenges and joys

of being a scientist on the frontier of discovery.

Who said that? Who said that right there? Some guy, Neil DeGrasse Tyson. Who's that guy? Lisa, congratulations on the book. Thanks for coming through town. Thanks so much for having me. All right. And next time I come to your office, we have to reenact some Carl Sagan things. Absolutely. I think it's going to be this year because it would have been Carl Sagan's 90th birthday. You should come. We should sit there and we both should think about what he'd want to do now.

All right, we'll work something out, I promise. And Matt, good to have you here in person. Oh, such a joy. Look at this. Look at this. Real, real. Can I do that to him? Matt exists. He's not a bot in Los Angeles. It's real. I'm not some avatar. And he's very happy he's sat in the middle of us. That's what I came here for. I came here for the physical touch. We've been lacking it in recent years. It's really a facial.

That's how you should think about it. A facial massage. A massage, yeah. And keep that podcast going. Bag it. Probably Science. That's it. Very good. Yeah. And I finally remembered it correctly. You got it dead on. Probably Science. That's the one. All right. All right. After this interview with Lisa Kautenegger, I'm reminded, explicitly reminded, that the best scientists out there are those who are still kids. What does a kid do? They...

Turn over rocks, look behind trees. They're curious about everything, everything, because the whole world is a frontier to them, a frontier of exploration. If you carry that into adulthood, then the universe is there for you to reach out, explore, discover. And then you have to pick up some math along the way so that you can speak the same language that the universe does. But when you do, oh my gosh, what a joy it is to be a child again.

Not many adults get to make that claim, but those adults on the frontier who are scientists do. That is a cosmic perspective. Until next time, this is our talk. Keep looking up.

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