Cosmic Queries – Silicon Aliens with David Grinspoon

Can there be life on planets without magnetic fields? Neil deGrasse Tyson and comedian Chuck Nice discuss exoplanets, extraterrestrials, and answer extraordinary questions from our fans with astrobiologist, David Grinspoon.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  On the next episode of StarTalk, it's a Cosmic Queries edition with, of course, Chuck Nice, and we have as our guest David Grin spoon, a friend and colleague. His expertise is on exoplanets, the search for life, and astrobiology. And we have some great questions coming up for you. Like, is carbon-based life the only kind of life that can exist? Is it the only kind of life we're searching for? Might we be missing something? And if we do find life, is there a protocol? Also, what would an Earth-like planet that sustained life be like if it had no atmosphere?

• 0:40Neil deGrasse Tyson?

  And will Earth ever become Venus? With a runaway greenhouse that's nearly 1,000 degrees Fahrenheit on this next episode of StarTalk.

• 0:55Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 1:09Neil deGrasse Tyson?

  David, welcome back to StarTalk.

• 1:10David Grinspoon?

  Hey, guys. Thank you. It's great to be here. Great to see you both.

• 1:15Neil deGrasse Tyson?

  Yeah, we count you as a friend. You've been on many, many times. And on your resume here, I've got you as Senior Scientist at the Planetary Science Institute, and that's in Arizona, is that correct?

• 1:26David Grinspoon?

  That's in Arizona. I'm in the Washington DC area through the magic of the interwebs. Where PSI, Planetary Sciences, to to sort of distribute it. We have people all over the place.

• 1:38Neil deGrasse Tyson?

  And I'm reminded, you're author of Chasing New Horizons. I see what you did there, because there is a mission to Pluto called New Horizons. And as well, Inside the Epic First Mission to Pluto. Like Chuck, you see what he did there? He's very expectant that there'll be more missions to Pluto.

• 1:56Chuck Nice?

  Right, right. By the way, the subtitle of that New Horizons was Screw You, Neil.

• 2:07Chuck Nice?

  That was, uh, that was the...

• 2:08Neil deGrasse Tyson?

  I see. It was implicated in the demotion of Pluto.

• 2:11David Grinspoon?

  Chuck, that's the implied subtitle, come on.

• 2:14Neil deGrasse Tyson?

  Oh, the actual subtitle.

• 2:16Chuck Nice?

  Okay, I'm sorry.

• 2:19Chuck Nice?

  Yeah, but let's not forget about, uh, my favorite Dr. Funky Spoon book, if I recall correctly, uh, is Earth in Human Hands, because it's all about how we are shaping this planet. And, uh, if you want to know some great information about climate change and the, uh, anthropocene, uh, you should check out that book, man, because it's, uh, it helped me. It's really very cool.

• 2:43Neil deGrasse Tyson?

  Wow, I didn't know you're now his agent. Okay, fine, I get to know that.

• 2:47David Grinspoon?

  No, Chuck's, Chuck's just my, my, my, like, prime audience. If, if, if he likes it, then I know I did something right, so...

• 2:54Neil deGrasse Tyson?

  Well, well, tell us about, tell us about that book. Because if you're, if you're a planetary expert, then Earth is simply another planet. Then you get to compare it, but, uh, you know, this, its strengths and weaknesses.

• 3:06Chuck Nice?

  Neil!

• 3:07Neil deGrasse Tyson?

  Susceptibilities.

• 3:08Chuck Nice?

  He does that in a book, actually.

• 3:10Neil deGrasse Tyson?

  That's what I meant. So I just want you to, so, let's take me there for a few minutes.

• 3:13David Grinspoon?

  Yeah, well, so, so I, I just thought it would be, I thought it would be cool to, uh, look at, um, sort of the question of, you know, the perennial question of what are humans and what makes us different, if anything, from the perspective of astrobiology and planetary science? And try to look at humans as this sort of thing that's happening to the planet? And how, how that fits into history? And then hopefully, how that view of ourselves can help us, uh, in a constructive way, think about our future, you know? So it's basically, it's the, uh, the astrobiologist's view of, you know, if you were an alien with a long attention span watching Earth,

• 3:53David Grinspoon?

  then in this recent stretch of time, you would have seen something really weird happen to our planet that has never happened to it before. You know, where the night side lights up and the atmosphere changes and every, everything changes. And, and what does that sort of look like from a planetary perspective? That was sort of the goal of, uh, Earth in Human Hands.

• 4:11Neil deGrasse Tyson?

  Okay, cool. And when, when was that published?

• 4:13David Grinspoon?

  That was published in, uh, 2017.

• 4:16Neil deGrasse Tyson?

  2017 and the date on the New Horizons book?

• 4:19David Grinspoon?

  That was um 2018. That was a busy little stretch for me.

• 4:25Neil deGrasse Tyson?

  Wow, okay, alright.

• 4:26David Grinspoon?

  I'm still recovering from all that.

• 4:30Neil deGrasse Tyson?

  Very, very cool. And we also have you listed here as a musician. Are you active or you just sort of play at home where no one's listening?

• 4:36David Grinspoon?

  Well, actually, one of the things that's wonderful for me, and I think for a lot of people about this stage where the pandemic maybe isn't over, but is easing up a little bit is the return of live music. And I've been really enjoying that both as a listener and fan and also as a performer. And I have been playing. I'm in a new band, actually, here in the DC area. We're called The Easy Way. And it's kind of a funk soul uh thing. And it's uh we've just started playing. We played, we played four gigs now.

• 5:09Chuck Nice?

  And are there any other scientists in the, in the band with you?

• 5:12David Grinspoon?

  No, but uh one, one of the other guys that our lead singer, he works at NASA. He's not a scientist, but he's a NASA dude.

• 5:20Chuck Nice?

  Okay.

• 5:21David Grinspoon?

  So we do NASA does represent.

• 5:23Neil deGrasse Tyson?

  So, so Chuck, you got questions for us? I haven't seen them yet. I don't know if David has.

• 5:28Chuck Nice?

  Uh, I'm sure I, uh, I, listen, I haven't. So I don't think anybody has.

• 5:33Neil deGrasse Tyson?

  This is a cosmic query, so tell us what you got.

• 5:36Chuck Nice?

  Here we go. You want to jump into this? Let's do it. Let's uh, let's pop things off with Trevor C. Mills. Trevor says, hey, Dr. Tyson, Dr. Grinspoon, as well as Chuck, uh, I hope this finds you well. This is Trevor from Augusta, Georgia. At what point in our search for extraterrestrial life do we start a church, a search for non-carbon based life? And what are some good candidates aside from silicone? So.

• 6:06Neil deGrasse Tyson?

  Okay.

• 6:07David Grinspoon?

  Yeah, good question. You know, the thing is, I would say there's not one specific point. It's almost like more a perspective we have to keep in mind and remember that this search needs to be conducted with the humility of the realization that we don't really know what we're looking for. We have some hunches about what's universal about life, and we know that carbon chemistry in water is a basis that can work, and we have good reason to believe that that could be functioning elsewhere because the conditions are available for it other places. So it's a good thing to look for because we know it can work, and we know, we sort of know how to look for it. But we should keep in mind that we

• 6:51David Grinspoon?

  don't have any solid reason to believe that that's the only kind of life. We haven't thought of any other, nobody's constructed or invented in a lab another kind of life that works as well, but that just, that could be because we're dumb, not because the universe doesn't know how to do it.

• 7:07Neil deGrasse Tyson?

  We do it in our movies. Our movies, we do it 100 times over.

• 7:09David Grinspoon?

  Yeah, it happens in movies. And you know, there is this move in NASA astrobiology to look for what we call agnostic biosignatures, which means not trying to assume as little as possible and looking for sort of more universal things that may not depend on carbon, you know. But then you get into this question, what do we even mean by life? And what does life do? But you could talk about, you know, chemical disequilibrium, life changing the chemical balance of its environment in a way that non-life probably doesn't. And if you go that route, it doesn't have to be carbon-based. It just has to be something that's multiplying

• 7:48David Grinspoon?

  itself and using energy. And so, so we do have ideas about how to look for non-carbon-based life, and I think we, it's good to be reminded, so thank you for the reminder, that we should keep that in mind as we search. But our search does tend to be focused on, quote, "life as we know it," partly because that's what we know how to look for.

• 8:11Neil deGrasse Tyson?

  So often people will swap, try to swap silicon in for carbon in the molecule. And many sci-fi movies that have attempted other chemically based life have done that with silicon. And can you tell me why silicon would be such a attractive next option?

• 8:31David Grinspoon?

  Yeah, because in some ways silicon is a lot like carbon in that, you know, if you look at the periodic table, we all remember the periodic table from the wall of our science classroom and it's got, you know, in the upper left, it's got hydrogen and below hydrogen are all the things that bond like hydrogen with like one electron. And sort of in the middle of that chart is carbon at the top and then below it are all the things that bond like carbon. Carbon makes four bonds with other things and that's the basis of organic chemistry, which is the basis of life. So you look right below carbon, the next thing down is silicon. You think, okay, silicon, that's gonna be kind of like carbon, maybe you can make biomolecules out of that.

• 9:12David Grinspoon?

  So there's a good logic to it, but the problem is silicon bonds are not like carbon bonds. What's great about carbon is not just that it bonds to four other things, so it can make this whole, you know, complex Lego set of molecules.

• 9:26Chuck Nice?

  Well, then it doesn't sound like it works. It doesn't sound like it. It sounds like it's people making a leap because it's similarities, but that's like me saying, you know, Obama has large ears, he's black, I could be president, you know? No, no Chuck, no you can't, you cannot.

• 9:49David Grinspoon?

  It is kind of like that. It depends on what features you're focusing on.

• 9:54Neil deGrasse Tyson?

  Don't agree with Chuck on that.

• 9:56David Grinspoon?

  Well, no, but I mean.

• 9:57Neil deGrasse Tyson?

  Don't egg him on.

• 9:58David Grinspoon?

  I'm sorry Neil, but Chuck has a point here. It depends on what characteristics you're focusing on.

• 10:03Neil deGrasse Tyson?

  You are under no obligation to agree with Chuck on this show.

• 10:04David Grinspoon?

  And the fact that silicon bonds to four other things makes it like carbon, but the problem is the nature of those bonds. Carbon bonds are also kind of floppy and loose and can, you know, carbon can get into all these like weird configurations which make proteins and things. Silicon bonds tend to be really stiff and, you know, they don't make those complex configurations the way carbon bonds do, so.

• 10:27Neil deGrasse Tyson?

  For those who can't see, David Greenstone was just vogueing in the last few moments. Shaping his hands around his face.

• 10:34David Grinspoon?

  Chemical voguing.

• 10:35Neil deGrasse Tyson?

  Imitating the flexibility or rigidity of carbon.

• 10:38David Grinspoon?

  Carbon? Silicon.

• 10:43David Grinspoon?

  Silicon likes to, silicon likes to strike a pose, stick to it, yeah.

• 10:47Neil deGrasse Tyson?

  Alright, okay, gotcha. And, and so that's less flexible when life is experimenting on the diversity of what it may need to thrive in an environment.

• 10:56David Grinspoon?

  Yeah.

• 10:57Neil deGrasse Tyson?

  That's a fair statement.

• 10:58David Grinspoon?

  And, and I don't think it makes like, carbon makes polymers, you know, the big molecules, where it's not just carbon, but it's attached to lots of other things. Silicon makes, you know, silicon oxygen chains and things like that, but I don't think it makes the kind of just diverse molecule set that makes carbon so good for life.

• 11:17Neil deGrasse Tyson?

  I, I would add, just from an astrophysical point of view, there's like five times as much carbon in the universe as there is silicon. So you don't even need to appeal to silicon because carbon is there for you and it's your friend.

• 11:31Chuck Nice?

  So to both of you, with respect to this, are there any conditions in the universe under which circumstances cause different reactions to these elements where they might behave in such a way to do something like make life? Or is the periodic chart the same no matter what, no matter where?

• 11:55David Grinspoon?

  The elements are going to be the same, but your question is good. Are there conditions in which the reaction types, the behavior is going to be different? And, and the answer is yes, there are conditions in which it's different. And that's why we have to be careful to not be too earth-centric. But has anybody come up with a set of conditions that we're likely to find somewhere where you can show that silicon's going to do the right thing to make life? The answer is no. But that may be just, again, be a limit on our imagination.

• 12:24Neil deGrasse Tyson?

  And as any, as any good scientist, you gotta sort of not only know your limits, but be prepared to shatter them as you, as you take every next step. Going forward. Chuck, you got another question for Dr. Funky's moon here?

• 12:37Chuck Nice?

  Yep, yep, yep. This is Emily, either Talis or Talias, one or the other. Uh, cause there's a double L. So, hi Chuck and Neil. Greetings from Paris, France. So maybe not either one of those pronunciations. Maybe not. Maybe not. And then she goes, uh, oh, look at this. Chuck, feel free to butcher my name. I can't wait to hear what you call it.

• 13:01Neil deGrasse Tyson?

  Oh, people setting you up. Oh.

• 13:04David Grinspoon?

  That was good preemptive, uh, consideration.

• 13:08Chuck Nice?

  Yeah, tell me about it. All right. She goes, I was wondering what would happen if we were to discover intelligent life outside of Earth, of course, but less advanced than we are. First, how would we discover it and confirm that it is indeed less intelligent? Well, that's pretty easy. And second, once confirmed, what would the next steps be? Is there a protocol for life discovery?

• 13:33David Grinspoon?

  Hmm. Yeah. First of all, I love the question and it's not one we think about very much because there's a set of assumptions, um, that are almost unspoken because of how long we've been assuming them and how frequently we assume them, which...

• 13:47Neil deGrasse Tyson?

  Actually, David, they'll remain unspoken until we come back from this break.

• 13:52David Grinspoon?

  They will remain unspoken a little longer.

• 13:55Neil deGrasse Tyson?

  Oh, just a little longer. Just a little longer. Let's find out about the unspoken protocol. That's the next installment of Mission Impossible. David's Unspoken Protocol About Encountering Life. Uh, we'll be right back after this first break.

• 14:19Speaker 03

  Hey, I'm Roy Hill Percival and I support StarTalk on Patreon, Bringing the Universe Down to Earth. This is StarTalk with Neil deGrasse Tyson.

• 14:36Neil deGrasse Tyson?

  We're back with StarTalk Cosmic Queries with David Grin spoon, a friend and colleague. And he's an expert on the solar system and astrobiology and all kinds of cool things such as that. David, how do we find you on social media?

• 14:52David Grinspoon?

  Uh, well, I'm, I'm still on Twitter, uh, at least today. And that's, that's, um, Dr. Funky Spoon.

• 14:59Neil deGrasse Tyson?

  Doctor, that's why we call you that, Dr. Funky Spoon.

• 15:03David Grinspoon?

  Yeah. And I'm on, I'm, I'm on, uh, Facebook, just under my name. And, and, uh, I'm on Mastodon now too, uh, which is I'm Dr. Funky Spoon at Qoto.org, Q O T O.

• 15:15Neil deGrasse Tyson?

  Funky or Funk Spoon?

• 15:16David Grinspoon?

  Funky, F U N K Y.

• 15:17Neil deGrasse Tyson?

  Oh, Funky, Funky Spoon, okay. All right, I'm Mastodon.

• 15:20David Grinspoon?

  I'm hedging my bets.

• 15:22Neil deGrasse Tyson?

  Okay. So Chuck, we left off with a question about what would happen?

• 15:28Chuck Nice?

  From, from Emily Talia.

• 15:30Neil deGrasse Tyson?

  Well, she's from France. Was Emily, how do you?

• 15:33Chuck Nice?

  Emily?

• 15:34Neil deGrasse Tyson?

  Emily, Emily. How do you Frenchify, Francophile Emily? But so, so she wants to know what happens when we find life that's less intelligent than us?

• 15:43David Grinspoon?

  Right.

• 15:44Neil deGrasse Tyson?

  That's hardly ever addressed in sci-fi storytelling.

• 15:47David Grinspoon?

  Yeah, or, because no one could imagine that we could be smarter. Well, it's hardly ever addressed in.

• 15:52Chuck Nice?

  Than anything else in the universe.

• 15:54David Grinspoon?

  Yeah, it's hardly ever addressed in sci-fi, but it's also hardly ever, uh, addressed in, um, in SETI itself, because there's always this assumption that anybody we find is going to almost surely be more quote, advanced than us, or have been around as a technological species or civilization much longer. And there's a good logic for that because, you know, on this, for one thing, on a cosmic timescale, we're just babies, right? You know, four and a half billion years of Earth, four billion years of life, depending on where you, you started, you know, a couple million years of being human and a few hundred years of being technological and less than a hundred years, or a hundred years of being

• 16:35David Grinspoon?

  radio friendly, you know? So, so we're babies. And so we always imagine that we are the neophytes and they're the wise ones and that there's an asymmetry in contact in that direction. And, you know, statistically, I think it's a pretty good argument, but it's an interesting question. What if we meet somebody who's, uh,

• 16:58David Grinspoon?

  You know, and there's a pretty narrow range there where they could be dumber than us and still considered, you know, still considered intelligent, but what if we, what if we did? And, and yeah, and how would we find them? Because presumably then they wouldn't have traveled here. So we have to stumble upon them.

• 17:15Chuck Nice?

  Or responded, or responded. So even, even if they're not traveling here.

• 17:20David Grinspoon?

  But what if we got, you know, what if we got lucky and sort of stumbled on a civilization that was sort of just becoming technological, but hadn't become interstellar yet. It seems unlikely.

• 17:31Neil deGrasse Tyson?

  No, that would just be a tech level. That's not an intelligent.

• 17:34David Grinspoon?

  No, that's a good point, too. Because, because you could argue there's, you know, there's always the whales, right? And the dolphins, they're really intelligent. They arguably have a civilization and a culture.

• 17:44Neil deGrasse Tyson?

  I saw that Star Trek movie, The Sable Whales, Star Trek movie.

• 17:47David Grinspoon?

  Yeah. So we could certainly find intelligent life that is not technological at the level we are. And, you know, as far as protocols, it's, there's, it's pretty vague. You know, there are protocols for SETI. If we think we found something, a radio signal, what do you do?

• 18:06Neil deGrasse Tyson?

  SETI, the Search for Extraterrestrial Intelligence, just the general term for that.

• 18:11David Grinspoon?

  Yeah. So, so the SETI, the Search for Extraterrestrial Intelligence community has protocols that if somebody thinks they've found a signal, then you don't announce it immediately to the public. First you verify it and you get another observatory to also find it. So you make sure it's not some weird mistake that your observatory is making and some local interference. But then once you're sure, then the, the protocol is complete transparency. You alert everybody, you know, so you're.

• 18:43Neil deGrasse Tyson?

  Unless the men in black get to you first.

• 18:45David Grinspoon?

  Yeah, that's right.

• 18:45Chuck Nice?

  Right.

• 18:46David Grinspoon?

  With a flashy thing. Yeah, that.

• 18:48Neil deGrasse Tyson?

  Yeah.

• 18:50David Grinspoon?

  So, you know, and then if, if somebody comes, you know, and lands a spaceship on Earth and contacts us, there's no real official protocol for that because it's not something that's just been, you know, you can argue whether it should be or shouldn't be, but it hasn't really been taken seriously enough by the, the sort of SETI and scientific community to develop a protocol for that.

• 19:16Neil deGrasse Tyson?

  All I know is that in today's world, if the aliens land and they say, take us to your leader, nobody's taking them to the White House.

• 19:25Chuck Nice?

  Yeah.

• 19:26David Grinspoon?

  That would really.

• 19:27Neil deGrasse Tyson?

  We'll take him, get a beer.

• 19:28David Grinspoon?

  It would present a conundrum. Where do you take them?

• 19:30Neil deGrasse Tyson?

  Yeah, you take him, get a beer at the corner pub. That's all you need to do.

• 19:34Chuck Nice?

  I imagine that my, my fantasy is that they would land and then we find out that we're so insignificant that they're actually filming a reality show.

• 19:46Neil deGrasse Tyson?

  Oh, oh, with them among us?

• 19:48Chuck Nice?

  Yes, exactly. Like, that is, that's what we rate as. Like, hey, let's go down there and like, like, basically, they're the Aston Kutcher of the universe and we're the ones that be.

• 19:59David Grinspoon?

  We're basically props.

• 20:01Chuck Nice?

  We're props. We're, we're straight up props.

• 20:03Neil deGrasse Tyson?

  Thank you, Chuck, for the, the happy thought there. Okay.

• 20:07Chuck Nice?

  All right, here we go.

• 20:09Neil deGrasse Tyson?

  By the way, I want to add something here. So David, I just want to add that if we count chimps as sort of the next smartest species to us, just, just for the sake of this, for this example, we can't have a meaningful conversation with them.

• 20:25Neil deGrasse Tyson?

  Think about it. And we got 99% identical DNA. So if, if we find another species that's sort of not as smart as us, what evidence do we have that we'd be able to communicate with them? Or worse yet, finding a species just that 1% smarter than us than we are to chimps, what hope do we have of them even being able to communicate with us because our simplest thoughts would transcend our most.

• 20:53David Grinspoon?

  Yeah, your, your example of chimps really is an interesting one and it kind of illustrates that something very recent has happened here on earth with humans that, for better or worse, where we have the, these qualities of, of language and culture and, and so forth. And, you know, not just, I mean chimps, you can argue have a kind of language, but the sort of syntactical language and ability to express abstract thoughts and all that, you know, it's pretty, it's pretty new. And it underscores how unlikely it probably is that we would connect with somebody else out there who seemed like an intelligent civilization,

• 21:33David Grinspoon?

  but also was less capable than us because, you know, it, it really illustrates that maybe we've just passed some kind of threshold. And on the other direction, yeah, so what if somebody is to us as we are to chimps? That may be possible, but it may also be that this sort of threshold is something that once you're over it.

• 21:54Chuck Nice?

  Then maybe you sort of can communicate even if you recognize that these guys are geniuses compared to us. It's an interesting question.

• 22:01Neil deGrasse Tyson?

  Chuck, that's his hu- that's David's human ego that just got into that. Yeah, we hit that threshold and we could communicate with any intelligent species smarter than us.

• 22:12Chuck Nice?

  I said maybe. Or maybe not. Maybe we're dumb as rocks compared to just about everybody in the universe.

• 22:21Neil deGrasse Tyson?

  Thank you. Thank you.

• 22:23Chuck Nice?

  I like that one. That's mine. That's the one I like.

• 22:26Neil deGrasse Tyson?

  All right, Chuck, keep them coming.

• 22:27Chuck Nice?

  All right, this is Sandra Bajani. Sandra Bajani says, "Good morning or evening, wonderful StarTalk hosts and listeners. This one came to me as I was flying to Seattle and looking out the window."

• 22:38Neil deGrasse Tyson?

  Love it. Love looking out the window.

• 22:39Chuck Nice?

  Yeah. "Why are black holes generally situated in the center of galaxies? Why that specific area? And yes, this is the kind of stuff that I think about while I'm on planes, looking out the window."

• 22:52Neil deGrasse Tyson?

  Yeah, that's good, because a whole lot of other stuff you can think about that create anxiety and things. And if you can think about black holes on a plane and not feel anxious, that's good.

• 23:01Chuck Nice?

  Yeah, I was gonna say that we actually have an astrophysicist here and it's not me.

• 23:09Neil deGrasse Tyson?

  So a black hole, our understanding of black holes tells us that you can get it from the death of a very high-mass star. The sun is not among them, and high-mass stars are very rare. So these would be stars that are dotted around the galaxy from a black hole that is the remnant of a supermassive star that lived out its life and died. And in the final collapse, it collapsed all the way to a black hole. We expect those black holes to be pretty much rare but everywhere, if you can picture that. So in other words, wherever you had stars being born, you'd have like maybe one of these. All right, so there are fewer of them than all the total stars by far.

• 23:54Neil deGrasse Tyson?

  But there's no part of the galaxy that would be without them. So that's for start. So that's one kind, those are called stellar black holes. Then, just empirically, we discovered that the centers of galaxies...

• 24:08Neil deGrasse Tyson?

  Have black holes in them. We just, it was a discovery in my life while I was in graduate school. This discovery took root. And we say, well, we've got one in our galaxy and one in a nearby galaxy. And then there's another galaxy over here. We, we can get data and we show a black hole. And so we extrapolated. We said, if it's in these three galaxies, it must be in all galaxies. It's hard enough to get those data. And those galaxies were very different from each other. So then we just went on the assumption that every big galaxy would have a supermassive black hole. And sure enough, Hubble telescope gets launched and every galaxy we look into and have the quality of data to know, they've all got a supermassive black hole. And we do not yet know how they were formed.

• 24:53Neil deGrasse Tyson?

  And the James Webb Space Telescope is exquisitely tuned to see the birth of galaxies. And from those data, we might be able to see material collecting in the middle to form the supermassive black holes that dot the center of every galaxy. And again, in a sense of it, a black hole, um, stellar black hole might be five, 10 times the mass of the sun. But the supermassive black holes in the centers of galaxies is hundreds of thousands, up to millions of times the mass of the sun.

• 25:23Chuck Nice?

  So, if it's, if, if it's consistent that it's the death of a star that makes that, do we see stars that have that mass in the universe? That might be able to create a supermassive black hole that coalesces a galaxy?

• 25:41Neil deGrasse Tyson?

  No.

• 25:42Chuck Nice?

  Do we see, no. Okay.

• 25:44Neil deGrasse Tyson?

  Yeah, stars give out at about 60 to 100 times the mass of the sun. We don't find stars more heavier than that. So we're not going to find a billion times mass of the sun star. We just have never seen that. And so that's why we think something else is making them.

• 25:58Chuck Nice?

  That's, has something else, that, that, that is, wow, that is a wonderful mystery.

• 26:03Neil deGrasse Tyson?

  Yeah, yeah, well, the universe brims with mysteries. That's why David and I have a job.

• 26:07David Grinspoon?

  And I, I, I love the fact that for the supermassive black hole, in, in our own galaxy, we can actually watch the stars orbiting it.

• 26:16Neil deGrasse Tyson?

  So. And at a Nobel Prize winning observations, uh, yes, we can, you, you're watching these stars do these loops and loops? And there's nothing there in the middle. Nothing.

• 26:27Chuck Nice?

  It's enough to make you really believe.

• 26:32Neil deGrasse Tyson?

  And you run the math on the orbits and the speeds and the distances and you get a black hole.

• 26:37Chuck Nice?

  You get a black hole.

• 26:38Neil deGrasse Tyson?

  Straight up.

• 26:39David Grinspoon?

  So cool.

• 26:39Chuck Nice?

  It's not, it's not a NASCAR track.

• 26:42Neil deGrasse Tyson?

  Nope.

• 26:42Chuck Nice?

  It's a black hole.

• 26:43Neil deGrasse Tyson?

  Ooh.

• 26:43Chuck Nice?

  That's very cool. Alright, here we go. Um, this is, his name is on another page, Gavin Mallow. And Gavin says, greetings from Beaver Creek. Hello, David, Neil, and Chuck. And that's Beaver Creek, Ohio. I forgot the Ohio part.

• 27:01Neil deGrasse Tyson?

  Okay.

• 27:02Chuck Nice?

  I'm curious about the possibility of life on an Earth-like planet that would lack the protective sleeve that Earth's atmosphere and magnetic fields supply us. What would life do to accommodate these relative extreme conditions? Could anything on Earth potentially be transmissible to an environment as such?

• 27:22Neil deGrasse Tyson?

  Ooh.

• 27:22Chuck Nice?

  Ha ha.

• 27:24David Grinspoon?

  Yeah.

• 27:24Neil deGrasse Tyson?

  Yeah, David, we got these, we got these protect, you know, our atmosphere protects us from meteors, it protects us from UV light, it's, you know, so we're here by the grace of the atmosphere. And so if there's a planet out there, Earth-sized, Earth-gravity, Goldilocks zone maybe, and doesn't have these protectorates, I mean, these protect, these protecting forces, what, what do we do?

• 27:50David Grinspoon?

  Yeah, that's, that's a great question. I'm, I'm less worried about the magnetic field part, which is the other thing that the questioner asked, because we're learning more that makes us wonder how important magnetic fields are in protecting the surface of a planet. Uh, we, we used to say that without, that it was the lack of magnetic field that made Mars lose its atmosphere, for instance, but more recent observations have made us question that, and the role of a magnetic field in protecting the atmosphere itself is not so clear. And then there's the example of, of one of my favorite planets, Venus, which has no intrinsic magnetic field, but because it has a thick atmosphere, it's still protected. In fact, Venus develops what's called an induced magnetic field, where just the, the

• 28:34David Grinspoon?

  solar wind itself sort of makes the upper atmosphere charged in such a way that it starts acting like it has a magnetic field.

• 28:43Neil deGrasse Tyson?

  And David, if memory serves, you wrote a book on Venus, too.

• 28:46David Grinspoon?

  This is correct, yes.

• 28:47Neil deGrasse Tyson?

  Wait, wait, you, sorry, you wrote a book on Earth about Venus.

• 28:49David Grinspoon?

  That's right, I was not on Venus when I wrote the book, but I wrote a book on the subject of Venus.

• 28:55Neil deGrasse Tyson?

  And the title of that book was what?

• 28:56David Grinspoon?

  That's Venus Revealed.

• 28:58Neil deGrasse Tyson?

  Revealed, there you go.

• 28:59David Grinspoon?

  Yeah.

• 29:00Neil deGrasse Tyson?

  Okay. You've been at this for a while.

• 29:02David Grinspoon?

  Yeah, yeah, so magnetic fields, I think life could, life would find a way, but, um, but an atmosphere fills so many roles, not only does it protect from dangerous radiation, ultraviolet light and cosmic rays, but of course it also serves to transport, um, you know, think of Earth and the role of oxygen and carbon dioxide in plants and animal life, the transporting of, um, chemicals that are involved in, in the metabolism of organisms, of, you know, trading energy between molecules and so forth. It's hard to imagine life evolving on the surface of a planet without an atmosphere.

• 29:45David Grinspoon?

  Now, of course, there are places in the solar system without atmospheres where we think there might be life on the inside, like, say, Europa. And so one could imagine an Earth-like planet without an atmosphere that still had the chemical stuff happening and the, and the, and the energy transformations on the inside so that maybe you'd have internal life, um, in, in, in the interior of the planet. But, but, but an atmosphere is so integral to the kind of life that we have on Earth that it really sort of stretches the imagination to, to think of how you would get a biosphere without an atmosphere.

• 30:23Neil deGrasse Tyson?

  And, and, and there's nothing wrong with stretching the imagination.

• 30:26David Grinspoon?

  This is true, that's why we like these kinds of questions.

• 30:28Neil deGrasse Tyson?

  Yeah, yeah, yeah. Chuck, we gotta take a quick break and

• 30:31David Grinspoon?

  Okay.

• 30:32Neil deGrasse Tyson?

  David will be back in just a moment for our third and final segment with David Flunky Spoon, Grin Spoon, on StarTalk.

• 30:53Neil deGrasse Tyson?

  We're back, StarTalk, Cosmic Queries, all about the solar system and searching for life and astrobiology with one of the world's leading experts on these very subjects, David Grin spoon, a friend and colleague at the Planetary Science Institute. It's self-based in Arizona, but he is distributed, he's part of the PSI At Large Community, based in Washington DC. Always good to have you, David. You're a friend of our show and thanks for responding.

• 31:20David Grinspoon?

  Always great to be here with you guys.

• 31:22Neil deGrasse Tyson?

  So, let's make this kind of like a lightning round, alright? And we'll speed it up as we go along. Because we only got through like five questions and we got more, tons of them. Let's keep going.

• 31:31Chuck Nice?

  Alright, here we go. Eric Sharakun, or Sharakun, says, "Hey, from Boston. What does Dr. David Grin spoon think about the James Webb Space Telescope's recent exoplanet discovery? Particularly that it appears similar to Earth in size and in composition."

• 31:55Neil deGrasse Tyson?

  Yeah, David, you know, when we designed the damn telescope, it was to look for galaxies at the edge of the universe. And then you planet people are starting to use it to like look at stuff right in front of our noses. So, who, when, what, in the dark of what night did that?

• 32:09David Grinspoon?

  Yeah.

• 32:10Neil deGrasse Tyson?

  Did that portfolio start?

• 32:11David Grinspoon?

  Who do you know? Who do you know that you were able to pull this off?

• 32:15Chuck Nice?

  When did that happen?

• 32:16David Grinspoon?

  Yeah. Alright, well, first of all, Boston, my hometown, yay, go Celtics. And, um, the, uh, it's wonderful what I think of that is, you know, like, as Neil implies, the, the, the Webb was not designed to look at exoplanets. It was designed for galaxies and other things like that, astrophysical targets. But, um, you know, I chalk it up to the fact that the universe is just so... Incredibly productive when it comes to planets, much more than we thought even when people started designing the web. And so in a way, it's luck. You know, there turns out, web is sort of marginal for exoplanets, but there's so many good targets that we're starting to find them. And the exciting prospect now is that we can start to see what their

• 33:01David Grinspoon?

  atmospheres are made of. Even though, again, web is not the ideal instrument for that, and we've got other ones, of course, we want to build in the future, that will be more ideal. We're going to learn some really cool and important things about our planets in nearby star systems. And that's just-

• 33:17Neil deGrasse Tyson?

  So you're being opportunistic. And that's-

• 33:19David Grinspoon?

  Absolutely.

• 33:19Neil deGrasse Tyson?

  That's a good thing.

• 33:20David Grinspoon?

  Absolutely. Yes.

• 33:21Neil deGrasse Tyson?

  All right, Chuck, keep it coming.

• 33:22David Grinspoon?

  All right, let's just keep going.

• 33:24Neil deGrasse Tyson?

  Succinct answer, David, for this third round. Okay, go.

• 33:28Chuck Nice?

  Keeping it moving, Kyle Marsden says, "Hey, yo, hey, yo, hey!" I didn't say that, he did. "How many Earth-like planets do we know about currently that reside in habitable orbits?" Is there a number?

• 33:41David Grinspoon?

  You know, there's a lot of marginal ones. I would say, I would say a handful, you know, which is, which is pretty good. Because when you come, when it comes to saying habitable orbits, some of them, we're sort of guessing, because it really depends on whether they have an atmosphere or not, and what the details of their climates. But there's a, you know, there's a good dozen or so that seem like pretty good candidates.

• 34:07Neil deGrasse Tyson?

  David, there are 5,000 planets in the catalog right now. You're telling me there's only like a dozen?

• 34:12David Grinspoon?

  Well, I'm saying, I'm saying-

• 34:13Neil deGrasse Tyson?

  Goldilocks planets?

• 34:14David Grinspoon?

  I'm saying ones that we, and it depends on what you mean by Earth-like, okay? These are all gray area terms. But I'm saying, I'm saying roughly Earth-sized, and definitely good candidates to be in the habitable zone, and maybe have liquid oceans and things like that. It's a small but growing number.

• 34:33Neil deGrasse Tyson?

  Okay, all right. So that would be if we did it in percentages, it was 10 out of 5,000. So what is it? It's 1 out of 500. So that's still pretty low. That's like a fifth of 1%.

• 34:44David Grinspoon?

  Yeah, but you know, but a lot of those 5,000 are ones that, that will, could be. These are, I'm giving a conservative number for ones that we can say, yes, that's Earth-sized, and yes, that is really-

• 34:57Neil deGrasse Tyson?

  So there's some in the, in the running, in the running?

• 34:59David Grinspoon?

  Absolutely.

• 34:59Neil deGrasse Tyson?

  Okay.

• 35:00David Grinspoon?

  But it's still big news. It's still big news when we find one. Yeah, that's why it's so exciting that, you know, this one that was just mentioned, because like, oh, yes, that's Earth-sized, and it seems to be in the habitable zone. That's, it's still news.

• 35:12Neil deGrasse Tyson?

  Yes, yes. Which is a good thing. It means that people are still excited and aren't enough of them to get bored with it yet. Chuck, keep it coming.

• 35:22Chuck Nice?

  Alrighty, here we go. This is Zeki Masjid. I think. I mean...

• 35:30Neil deGrasse Tyson?

  You're the reader here, so it's always what you think.

• 35:34Chuck Nice?

  Zeki Masjid. Okay, you're right. Exactly. Yeah. I'm gonna tell you the truth. I really don't think that, but that's about as close as I can come. Okay? He says, "Hey Neil, hey David, and Seth MacFarlane's The Orville 25th Century Life has progressed far into the galaxy, solved societal, health, and technological issues, and eliminated money as a form of currency. Do you think this future is viable? And what steps do present-day humans need to take individually, as well as on a larger scale, to walk towards that goal? How can we push for science literacy globally?"

• 36:08Neil deGrasse Tyson?

  Wow, okay. So David, answer that in three sentences.

• 36:11David Grinspoon?

  I would say, in three sentences, yes, I think it's possible, though not assured. And that the path is not gonna be smooth between here and there, and that the key is some sort of a globally enlightened society where we guide ourselves with the recognition that we are one planetary species, despite all of our wonderful differences.

• 36:43Neil deGrasse Tyson?

  Just as a guiding force, operating on our future decisions.

• 36:48Chuck Nice?

  Right. Well, there you go. Here's your answer. You were screwed.

• 36:52Neil deGrasse Tyson?

  And I think, just to remind people, I think the original Star Trek, after which so much of The Orville is, so much of it is inspired, forces operating within the storytelling of Orville. If I remember correctly, the reason why there's no money is because they... They someone developed a replicator where you if you need another one of something just make another one in it. So you didn't have to go out and buy it or earn money to obtain it.

• 37:18David Grinspoon?

  It's post scarcity.

• 37:21Neil deGrasse Tyson?

  Correct. A post scarcity world where anything could just come out of a box, a machine that you you create. And so that changes what people care about, what they value and all the rest. But one of them is you don't need money.

• 37:32David Grinspoon?

  It's interesting because money is just a belief system. Anyways, we all fool ourselves into thinking it has value. So it does have value. So we could always change our minds collectively about that.

• 37:42Neil deGrasse Tyson?

  Right, right, right.

• 37:43Chuck Nice?

  And the other thing too is once they got rid of money, they people started to do what they wanted to do, which so you naturally end up with a passion for life because everybody's doing what they want to do.

• 37:57Neil deGrasse Tyson?

  Rather than what they have to do in order to pay the rent.

• 38:00Chuck Nice?

  Exactly.

• 38:00David Grinspoon?

  Okay, but then how do you explain Ferengis?

• 38:04Chuck Nice?

  Well, yeah, they're greedy little bastards. That's how you explain them. They're just greedy little bastards. They don't care. They have it all and they still want more.

• 38:14Neil deGrasse Tyson?

  But Chuck, what you said is deep because it it what it would do, it would liberate the creativity of every citizen of the world to contribute in whatever way best floats their boat. And they'll probably be better at that than anything else they would have done, right? Because they'll do it because they want to.

• 38:30Chuck Nice?

  Right, because yeah, yeah, exactly.

• 38:31Neil deGrasse Tyson?

  They have to. Deep.

• 38:33David Grinspoon?

  I like it. I like it. I think I think we should just like start that world right now. What are we waiting for?

• 38:38Chuck Nice?

  No.

• 38:42Chuck Nice?

  Ah, that's great. And on January 17th, 2023, a revolution took hold, spread like wildfire across the base of the globe. All right. So this is Cameron Bellamy, who says, greetings from Baltimore, Maryland. What aspects of a planet's climate are planetary scientists looking for when evaluating planets for potential to support life? Additionally, how close to these planets need to be to Earth to look for these aspects in the planet's climate?

• 39:16Neil deGrasse Tyson?

  I like that. Yeah.

• 39:17David Grinspoon?

  Yeah. So that's it's it's a good question. So I mean, the basic. Factor that we're always very focused on is a climate in the range where water would be predominantly liquid. And again, that could just be our own bias because, you know, as we talked about it earlier, maybe we're not smart enough to think of other kinds of life that don't need water. But Earth, so much of what makes Earth the way it is, is because the climate balance is such that we live on a water planet. And that is, in every cell of your body, is liquid water interacting with organic molecules. So, so that's the number one thing. There's enough greenhouse gases, um, carbon dioxide. In a good way. Yeah, exactly. In a good way.

• 40:01David Grinspoon?

  A good amount of greenhouse gases, carbon dioxide, water, a little methane, sulfur dioxide. These are the gases that absorb infrared radiation and make a planet warm. But not so much that you have a Venus that's just too hot for liquid water. So that, that's the, the sort of prime directive, if you will, for, for habitability. Um, and what was the second part of the question? Um, what do we look for, um, to, um? Oh, how far away? How far away? How far away? Yeah. Again, you know, with the tools we have now, we can, there's, it's, it's very difficult to, um, tell what's in a planet's atmosphere unless it's not just distance, the geometry has to be right.

• 40:43David Grinspoon?

  If we have what we call a transiting planet, so it passes in its orbit right between us and its star, then you can look at the radiation coming from that star as it passes through the atmosphere and see how it's filtered out and what molecules are there. But it's easier to do that if you're, you know, within a few hundred light years than if you're thousands of light years. But. Holy crap. But if we, as we get better instruments, um, that we want to build in the future, we'll be able to greatly expand the number of planets we can do that for.

• 41:11Neil deGrasse Tyson?

  And just a quick addition here. I remember watching Star Trek and just, you ever notice, David, Chuck, they never wore spacesuits when they went down to planet surfaces?

• 41:20David Grinspoon?

  Right.

• 41:21Neil deGrasse Tyson?

  Have you ever thought about that?

• 41:22David Grinspoon?

  Yes.

• 41:26Neil deGrasse Tyson?

  No, they never worked, because at some point, Spock would say, "Oxygen/nitrogen atmospheres, Captain."

• 41:34David Grinspoon?

  Right, it's a class M planet, Captain.

• 41:36Neil deGrasse Tyson?

  But I would hear that, and it was as though, "All we have to do is find an oxygen/nitrogen planet to move to." And then I realized, and David, correct me if I'm wrong here, if it has oxygen, something's making the oxygen. So, so you are already looking for planets that have some kind of life forms on it, to create that atmosphere in the first place. It's not that there's all kinds of random atmospheres that exist on all the planets, and pick the ones that you happen to be able to breathe. There's, there's active stuff going on there.

• 42:07David Grinspoon?

  Yeah, the reason why, the reason why we have a breathable atmosphere is because there's life here.

• 42:13Chuck Nice?

  Right.

• 42:14David Grinspoon?

  And so, any planet you find with that kind of atmosphere would be very surprising. Like, like you say, Neil, what, what, what else would be making an atmosphere with just that mixture? It's hard to imagine that it's not brimming with life.

• 42:26Neil deGrasse Tyson?

  Right, right.

• 42:27Chuck Nice?

  So cool.

• 42:28Neil deGrasse Tyson?

  Okay, a couple more. Chuck, man, we're blowing through these, very nice.

• 42:31Chuck Nice?

  Right, yes we are, yes we are, here we are.

• 42:33Neil deGrasse Tyson?

  Now, we, we gotta speed up even more, so David, soundbite mode, okay? Remember, so ABC News just put a microphone in front of your lips, and they're gonna soundbite you for the evening news. So here it is, go Chuck.

• 42:46Chuck Nice?

  All right. Hello Chuck, hello Neil, hello Dr. Funky Spoon. Um, okay, here we go. Does weed still work in space? Or are the THC crystals too fragile for space? What temperature, what hemp crop would be best to grow on Mars?

• 43:09David Grinspoon?

  I'll say, I don't know that the experiment's ever been tried, but in all seriousness, one thing I wonder about is...

• 43:18Neil deGrasse Tyson?

  You told me NASA never took weed into the space station?

• 43:20David Grinspoon?

  Not that, not that I know of, but I, I will say, in all seriousness, one of the big problems with astronaut health is eye pressure, ocular pressure. And one of the things that is well-established that cannabis does medically, is good for glaucoma, because it reduces ocular pressure. So I've always thought, and I've kind of whispered this to a few people at NASA, but like, "Why don't you try that?"

• 43:46Chuck Nice?

  Right on.

• 43:47Neil deGrasse Tyson?

  Okay.

• 43:48Chuck Nice?

  Yeah, yeah, you don't, you don't have to, you don't have to smoke it. We have gummies.

• 43:52David Grinspoon?

  Exactly.

• 43:52Neil deGrasse Tyson?

  Tell me about the soils of Mars. Can you grow anything there?

• 43:55David Grinspoon?

  Yeah, I mean, if you could grow, uh, anything, I mean, the thing, uh, you know, cannabis is just another plant. So if you grow tomatoes, you're gonna be able to grow cannabis there. It's, uh,

• 44:05Neil deGrasse Tyson?

  Okay, so whatever.

• 44:06David Grinspoon?

  The soil by itself as of now probably isn't very, uh, isn't very fertile, you know, cause it doesn't, it doesn't have organic.

• 44:13Neil deGrasse Tyson?

  And you learn from the, from the book and movie, The Martian.

• 44:15David Grinspoon?

  Yeah, but it could certainly.

• 44:17Neil deGrasse Tyson?

  Add poop.

• 44:17David Grinspoon?

  You could certainly mix in, mix in a little, uh, either human generated or otherwise generated fertilizer and grow stuff on Mars.

• 44:26Neil deGrasse Tyson?

  Human generated fertilizer.

• 44:28Chuck Nice?

  Fertilizer, right on. Yeah.

• 44:31Neil deGrasse Tyson?

  I always knew you were full of fertilizer.

• 44:33David Grinspoon?

  Exactly. We call that HGF.

• 44:38Chuck Nice?

  Nice, nice.

• 44:39Neil deGrasse Tyson?

  One last one, Chuck. That's all we got time for.

• 44:41Chuck Nice?

  Here we go. This is, uh, Akshat.

• 44:48Chuck Nice?

  Oh, man.

• 44:50Neil deGrasse Tyson?

  Why does it take you as long to read the name as the question itself?

• 44:53Chuck Nice?

  Because I don't prepare.

• 44:55Neil deGrasse Tyson?

  Okay.

• 45:00Chuck Nice?

  Uh, uh, Patikar, that's it. Askap Patikar, who says this. Hey, hello and greetings from India. I was wondering whether Venus was once a habitable planet and their civilization was there, uh, living on the planet, but unfortunately they destroyed themselves due to extreme climate change.

• 45:21David Grinspoon?

  Yes.

• 45:22Chuck Nice?

  What does the climate history have to say about the evolution of the entire planet? Thanks, and I love the show.

• 45:28Neil deGrasse Tyson?

  Oh, and this is from, from India. Just wanna give a shout out.

• 45:30Chuck Nice?

  It's from India.

• 45:31Neil deGrasse Tyson?

  India's been growing their presence in space with satellites and space missions and things.

• 45:35David Grinspoon?

  Yeah, and they have a Venus mission that's announced, an Indian Venus mission that's going to be.

• 45:39Neil deGrasse Tyson?

  And maybe where that came from. Very good, okay. So, welcome to the company of spacefaring nations. I say to the nation of India.

• 45:46David Grinspoon?

  Yes, indeed. A short answer, I've often wondered that myself, but it's true that we think that Venus probably was habitable, although that's one of the motivations for our upcoming missions is to determine, was it really? We think it had oceans and lost them, but we wanna. Gather the evidence to be sure of that. Um, we generally don't talk about an ancient civilization on Venus, although one has to admit that we have not explored the planet well enough to rule that out.

• 46:12Chuck Nice?

  Okay.

• 46:13Neil deGrasse Tyson?

  Wait, wait, you said you don't talk about it. That implies you don't talk about it in public.

• 46:17David Grinspoon?

  No, no, no, I didn't.

• 46:18Neil deGrasse Tyson?

  You heard how he said that, Chuck. We don't talk about that.

• 46:20Chuck Nice?

  I did. We don't talk about that.

• 46:22David Grinspoon?

  No, I just made this. That's not amongst our...

• 46:24Chuck Nice?

  Like Bruno in that movie, in the Disney movie, we don't talk about Bruno.

• 46:28Neil deGrasse Tyson?

  Well, we don't talk about it.

• 46:29David Grinspoon?

  I meant that's not amongst our most favored hypotheses, but it's certainly not that thing we could rule out. Thanks for letting me clarify that.

• 46:38Neil deGrasse Tyson?

  Yes, thank you very much there. But clearly Venus does have a runaway greenhouse effect. And they're just worried. Maybe the Venus has knobs that got turned.

• 46:48Chuck Nice?

  Right.

• 46:50Neil deGrasse Tyson?

  Had it become what it is, and we should look at those very same knobs here on Earth.

• 46:53David Grinspoon?

  Yeah, no, I mean, a serious answer is that by studying what happened to Venus, we can be better prepared to understand changes in Earth's future. And that indeed is one of the big motivations for understanding what happened to the climate there.

• 47:06Neil deGrasse Tyson?

  You got it.

• 47:07Chuck Nice?

  Now, is that, is runaway greenhouse effect something that can happen under the conditions that we have? Like, our planet could undergo the same thing? Could that happen?

• 47:19David Grinspoon?

  It's a good...

• 47:20Chuck Nice?

  I'm just saying, like, not that we're make that, that it is going to happen, but is it possible here?

• 47:25David Grinspoon?

  People have, people have looked at this, and the answer is if you burned all the fossil fuels on Earth, of course, you would make things awful and uninhabitable for humans, but you probably would not trigger a Venus-style runaway greenhouse effect where all the oceans boiled off. But, but in the future, as the sun warms up, which it is slowly, in, you know, a billion years or so, um, then there probably will be a runaway greenhouse effect on Earth like there was on Venus in the past. So if we wait long enough, then the sun will help us do that.

• 47:57Neil deGrasse Tyson?

  So you hear that Chuck, when an astrophysicist says, "In the future." His next phrase was, "A billion years from now."

• 48:02Chuck Nice?

  A billion years. Always, yes.

• 48:05Neil deGrasse Tyson?

  That's some serious ass future that we're talking about here. Yeah, exactly.

• 48:08David Grinspoon?

  We have more immediate problems, but nonetheless, it's still interesting to picture that long-term future.

• 48:14Neil deGrasse Tyson?

  Let me add something and get David's blessing on this comment before we close it out. So, David, in all my readings on this, I agree that if you extracted all fossil fuels and burned them all, with none left, Earth would be hotter, but you would not have the runaway greenhouse effect experienced by Venus. What you would need to do is somehow dissolve all of the world's limestone and other repositories of carbon that's beyond just fossil fuels, or fossils, right? And if you put all of that carbon, add it to the carbon that the fossil fuel burning would have, then we could become a twin of Venus in that way. Is that fair?

• 48:56David Grinspoon?

  Yeah, I think that's right, because then, I mean, Venus has sort of, like, 100 bars, almost, of CO2, which is 100 times the atmospheric thickness of Earth. If you burned all of the fossil fuels, you're not going to get that much carbon in Earth's atmosphere. But yeah, if you dissolve all the limestone and sort of took all the carbon in Earth's crust and somehow put it in the atmosphere, I don't think anybody should try this, mind you.

• 49:20Chuck Nice?

  Yeah.

• 49:20David Grinspoon?

  Don't try this at home. Then I think you probably could turn Earth into Venus.

• 49:25Neil deGrasse Tyson?

  Yeah, okay. Alright, so we're not doing that, for sure. But anyhow.

• 49:29Chuck Nice?

  But the one thing we know for certain is that greenhouse effect is from carbon in the atmosphere. That is just the way it is.

• 49:39Neil deGrasse Tyson?

  Carbon dioxide.

• 49:40Chuck Nice?

  Carbon dioxide. So, carbon dioxide in the atmosphere, done deal, greenhouse effect. And we know that we are doing that through burning fossil fuels here, right now.

• 49:50David Grinspoon?

  Absolutely. We're going in that direction, and it's the wrong direction for us.

• 49:55Neil deGrasse Tyson?

  Okay, there you go. For our survival. Yes. All right, we gotta call it quits there on that down note. There, I was gonna say. I had a, Chuck, I had a good note, a high note. Kiss your kids goodnight. A couple of minutes ago, and then you had to just take it down. All right.

• 50:09David Grinspoon?

  I, wait, a few minutes ago, we were abolishing all money and like liberating human creativity.

• 50:14Neil deGrasse Tyson?

  We saved humanity in the last question. Oh, man. And then, of course, we destroyed it with this one. All right, that's, that's, that, those are the breaks. This is StarTalk Cosmic Query. It's one of our favorite variants on the StarTalk franchise. Neil deGrasse Tyson here, your personal astrophysicist. I want to thank David for coming back to StarTalk. He's a friend of the show. And of course Chuck Nice. Always good to have you there. Always a pleasure. As always, I bid you to keep looking up.