Bug Splat Galaxies with Mordecai-Mark Mac Low

What type of planets orbit black holes? Neil deGrasse Tyson and comic co-host Negin Farsad sit down with Mordecai-Mark Mac Low to crack open the mysteries of galaxy collisions, dark matter, and the massive planetary systems around black holes.

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

• 0:00Neil deGrasse Tyson?

  Negin, we learned all about colliding galaxies and the formation of planets.

• 0:04Negin Farsad?

  I had no idea how much banging and colliding and smashing there was in this universe.

• 0:09Neil deGrasse Tyson?

  All the time, coming right up on StarTalk.

• 0:14Neil deGrasse Tyson?

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

• 0:23Neil deGrasse Tyson?

  StarTalk begins right now.

• 0:30Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. This is going to be cosmic queries on the formation of planets in the universe.

• 0:44Neil deGrasse Tyson?

  I got with me my co-host Negin Fassad.

• 0:47Negin Farsad?

  Oh my God, hello.

• 0:48Neil deGrasse Tyson?

  Welcome back.

• 0:49Negin Farsad?

  I'm so excited. I have, I've, I've like peeped at some of these questions and they are.

• 0:55Neil deGrasse Tyson?

  Well, yeah, because they're already.

• 0:56Negin Farsad?

  Querylicious.

• 0:57Neil deGrasse Tyson?

  Ooh, querylicious. I love that. Very good. And just a reminder, you, you still have your Fake the Nation podcast.

• 1:05Negin Farsad?

  That's right.

• 1:05Neil deGrasse Tyson?

  Comes out every week, every week. And it's a delight anytime I hear you on Wait, Wait, Don't Tell Me.

• 1:11Negin Farsad?

  Thank you.

• 1:12Neil deGrasse Tyson?

  That's the NPR, right?

• 1:13Negin Farsad?

  Yeah.

• 1:13Neil deGrasse Tyson?

  It's a NPR mainstay.

• 1:14Negin Farsad?

  An NPR mainstay. I've got a lot of tote bags to prove it. We have a good time.

• 1:21Neil deGrasse Tyson?

  All right. Let me introduce you to my guest today. He's a longtime friend and colleague, Mordecai Mark McLough. Mordecai. Well, hello, Neil. It's weird to. It's only been thirty-seven years that we've known each other. Yeah. So we, I mean, we came up together, you know, through graduate school, not at the same graduate school, but we're about the same generation. And it was, he's one of the earliest hires into our brand new department of astrophysics. Number one. Oh, you were the number one hire. I am number one. Okay, that's another way to say it.

• 1:58Negin Farsad?

  Is that a way of saying that he's better than you?

• 2:02Speaker 02

  No.

• 2:02Negin Farsad?

  Is that what I'm understanding?

• 2:03Speaker 02

  He founded the department.

• 2:05Negin Farsad?

  Oh, gotcha.

• 2:05Speaker 02

  I was his number one hire.

• 2:08Negin Farsad?

  Oh, gotcha, gotcha.

• 2:08Speaker 02

  Let's be clear here.

• 2:09Negin Farsad?

  Okay, you're just better than everyone else here.

• 2:11Speaker 02

  Yeah, there we go.

• 2:13Negin Farsad?

  But Neil was still better than you.

• 2:14Speaker 02

  That's what we're looking for.

• 2:14Negin Farsad?

  Okay, got it.

• 2:15Neil deGrasse Tyson?

  Number one means he was hired first, not that he's the number one guy. We're all number one here. And what was a delight in your research profile is that you just need a powerful computer and the universe succumbs to you.

• 2:33Speaker 02

  Well, it's a good sandbox.

• 2:35Neil deGrasse Tyson?

  Tell me what you do, because most people's stereotype of the astronomer, astrophysicist, we're at the telescope, or maybe we're crunching numbers on, not numbers, but we're on a theorist's notepad, and you are in the middle of that.

• 2:51Speaker 02

  I'm a simulator.

• 2:52Neil deGrasse Tyson?

  Simulator.

• 2:53Speaker 02

  So I do, I run computer programs that...

• 2:57Neil deGrasse Tyson?

  That you write?

• 2:59Speaker 02

  Well, that I and my colleagues write.

• 3:01Neil deGrasse Tyson?

  Yes.

• 3:01Speaker 02

  That, um, that describe how parts of the universe behave using mathematical equations derived by theorists, but using the computer to derive consequences that would be absolutely impossible to do with pencil and paper mathematics. So when things get hairy, we pull out a computer.

• 3:25Neil deGrasse Tyson?

  Mmm.

• 3:26Negin Farsad?

  Do you ever like sim, use your powers of simulation for like, you know, a vision of a grilled cheese sandwich, or is it mostly just like space?

• 3:35Speaker 02

  Well, I would say that I may not do the grilled cheese sandwiches, but there is a simulator somewhere who does.

• 3:42Negin Farsad?

  Does, okay, okay.

• 3:43Speaker 02

  And they probably work for Kraft or someone.

• 3:46Negin Farsad?

  And they should be your next guest.

• 3:48Speaker 02

  There you go.

• 3:49Neil deGrasse Tyson?

  So, Mordecai, I remember when we were coming up, there was a catalog... Of galaxies, peculiar galaxies. In fact, it was called the Atlas of Peculiar Galaxies.

• 4:00Speaker 02

  Arpsworth.

• 4:00Neil deGrasse Tyson?

  Arp, yeah, Halton Arp. And we all scratched our heads, wondering, how would nature make objects that look like this?

• 4:09Speaker 02

  Like bug splats?

• 4:11Neil deGrasse Tyson?

  Yeah, the galaxies are just, what? What? And I think in our lifetime, bringing computers to bear on that problem, we would fully understand how you get a disturbed-looking galaxy.

• 4:28Speaker 02

  So that's actually an interesting story, because the very first simulation that was done of colliding galaxies that made a bug splat and reproduced these peculiar observations was done in the 1940s using lamps and photo detectors.

• 4:47Neil deGrasse Tyson?

  Hmm.

• 4:48Speaker 02

  And as an analog computer. Because the lamps simulated gravity, because light drops off in intensity just like gravity does. And that actually revealed the basic picture that you get these splats, these tidal tails, we call them. But then we came along and refined that insight.

• 5:10Neil deGrasse Tyson?

  With actual computers.

• 5:12Speaker 02

  Yes, but the first one was those photo detectors.

• 5:16Neil deGrasse Tyson?

  Interesting. That wouldn't be Holmberg, was it?

• 5:18Speaker 02

  I think it was.

• 5:19Neil deGrasse Tyson?

  Holmberg, yeah.

• 5:20Speaker 02

  You're right.

• 5:20Neil deGrasse Tyson?

  I remember that.

• 5:21Speaker 02

  Yes.

• 5:21Neil deGrasse Tyson?

  Yeah, so.

• 5:22Speaker 02

  You've written about this.

• 5:24Neil deGrasse Tyson?

  But I was just a triumph of the simulation modeling universe. Where, so there was a famous astronomer in the day. He would say, a Lexus that's wrecked in an accident is not a different kind of Lexus. It's just a wrecked Lexus. And so a wrecked galaxy could have been a perfectly nice galaxy, but then it collided with another galaxy. And with your computer, you can check what it looks like at every step.

• 5:57Speaker 02

  That's correct.

• 5:58Neil deGrasse Tyson?

  And then, and then look at the universe and find-

• 6:01Speaker 02

  Find those steps.

• 6:02Neil deGrasse Tyson?

  And all of those steps-

• 6:03Speaker 02

  Yes.

• 6:04Neil deGrasse Tyson?

  -being taken by colliding galaxies.

• 6:05Speaker 02

  And that's how we learned that bug splats turn into beautiful elliptical galaxies. Smooth, uniform, homogeneous, because they get complete- They're disk galaxies that get completely blenderized. And that's the origin of the elliptical galaxies. Furthermore, every galaxy in the universe has collided with other galaxies. That's how galaxies are made.

• 6:34Negin Farsad?

  Wait, so is it that like, when a ga- When two galaxies collide?

• 6:39Speaker 02

  Yes.

• 6:40Negin Farsad?

  Is it sort of like-

• 6:40Neil deGrasse Tyson?

  Say it more romantically, when two galaxies collide.

• 6:44Speaker 03

  When two galaxies collide.

• 6:46Speaker 02

  Come together.

• 6:48Negin Farsad?

  But when that happens, is it that like, they're at a stop sign and neither of them is willing to go? So then they just smash into each other?

• 6:55Speaker 02

  Well, it's like this. Galaxies are made of stars and gas and dark matter. And stars are very widely separated from each other. So the stars just go by each other. Maybe they tug each other a little gravitationally, but basically, they're not gonna run into each other.

• 7:15Neil deGrasse Tyson?

  If there were four bumblebees in the continental United States, flying randomly, there's a greater chance that two of them will accidentally bump into each other than two stars will collide.

• 7:27Speaker 02

  In galaxies. That's about right.

• 7:29Negin Farsad?

  Oh, I'm hearing there's a lot of space.

• 7:30Neil deGrasse Tyson?

  Yes.

• 7:31Negin Farsad?

  Is that what we're doing? Okay, got it, got it.

• 7:34Speaker 02

  However, gas is space filling. And so the gas runs into each other and lights up, huge shock waves, dust clouds running into each other, new stars forming, all that goes on during the collision.

• 7:48Neil deGrasse Tyson?

  I got a good analogy for colliding gas clouds.

• 7:50Negin Farsad?

  Okay.

• 7:51Neil deGrasse Tyson?

  Two hot marshmallows.

• 7:54Neil deGrasse Tyson?

  When they hit, they're stuck. Have you done this? You look at me like, what is he talking about?

• 8:01Speaker 02

  I am too.

• 8:02Negin Farsad?

  Have you roasted marshmallows and then like throw them at each other? Like, I have it, Neil.

• 8:08Speaker 02

  Neil, I don't know what kind of camping trips you went on. We ate the marshmallows.

• 8:13Negin Farsad?

  He's looking at us like we're the weird ones. Okay, so no, but I like this. So they don't, they, they, they stick together and then that's it. They become one marshmallow.

• 8:21Neil deGrasse Tyson?

  They become one marshmallow. And there's an edge between them and everything. So I, I, I'm bringing this up just as-

• 8:26Speaker 02

  But they don't emit X-rays.

• 8:27Neil deGrasse Tyson?

  No, they don't. Last I checked. So I, I'm bringing this up just as a triumph of the bringing-

• 8:33Speaker 02

  Numerical methods.

• 8:35Neil deGrasse Tyson?

  Numerical simulations to understanding the universe. And you made a career of doing just that. One of the, another great mysteries that we had to figure out was weird galaxies that had weird things going on in their, in their centers. And they give off a lot of energy and a lot of different wavelengths. And we came up with the unpoetic name, active galactic nuclei.

• 8:57Speaker 02

  Or quasars for the brightest ones.

• 8:59Neil deGrasse Tyson?

  Especially of late, this has been a big part of your, your, your objects of affection.

• 9:04Speaker 02

  It's one strand of my research, yes.

• 9:06Neil deGrasse Tyson?

  Oh, just one strand?

• 9:07Speaker 02

  Just one strand.

• 9:09Neil deGrasse Tyson?

  And so, so tell me about AGNs. What's the latest on them? Do they all have black holes?

• 9:15Speaker 02

  They all have black holes. That's what makes them so bright. Because black holes are the brightest objects in the universe.

• 9:23Neil deGrasse Tyson?

  This is where you come in and say, how could a black hole be bright?

• 9:25Negin Farsad?

  Yeah, how could a black hole be bright? I, I don't understand.

• 9:31Speaker 02

  Thank you for asking.

• 9:32Negin Farsad?

  And is there a way for the black hole in my soul to brighten up as well?

• 9:37Speaker 02

  Yes, yes, there is. Eat a lot. Because that's how black holes get bright. So you have gas. And we have already established that if you squeeze gas enough, it gets really, really hot. And if it's really, really hot, it emits a lot of radiation as the fourth power of the temperature. And so, what is better at squeezing things than a almost extremely tiny, extremely massive object, like a black hole? So, you have a black hole in gas, and particularly in the centers of galaxies, there's a lot of gas, because it all gets swept into the center, as you wish the vacuum cleaner would do, but anyway.

• 10:22Speaker 02

  So, here it is, all this gas falling onto the black hole, and there's not room for all that gas to fall in, so it gets squeezed, and squeezed, and squeezed, until it reaches a billion degrees Fahrenheit. And...

• 10:37Neil deGrasse Tyson?

  I was gonna clarify, is it Fahrenheit or Celsius?

• 10:40Negin Farsad?

  Yeah, no, thank God, okay.

• 10:41Neil deGrasse Tyson?

  You were wondering that too, right?

• 10:43Speaker 02

  Yeah, of course. So, when it's that hot, it's emitting in the X-rays, and the ultraviolet, and all that light is coming out, and that, a lot of it gets converted down into the visible, by running into dust clouds and stuff.

• 10:57Neil deGrasse Tyson?

  Just to back up on that, if you have an electric stove, when it's off, it just, it's just off.

• 11:03Speaker 02

  It's emitting in the infrared.

• 11:04Neil deGrasse Tyson?

  Yeah, just mildly, but then you turn it up a little higher, and then it feels warm, it's emitting more infrared, and then it becomes visible.

• 11:13Speaker 02

  But it's deep red.

• 11:14Neil deGrasse Tyson?

  Yeah, it's emitting visible light, but also still emitting all the more infrared than before, but it kind of stops there, at maximum.

• 11:22Speaker 02

  But if you keep cranking it up, it'll get orange hot.

• 11:25Negin Farsad?

  Wait, so you could have like a black hole in your kitchen?

• 11:28Neil deGrasse Tyson?

  Well, we're getting there, right.

• 11:29Speaker 02

  Not a good idea. X-ray emission is unhealthy for human beings.

• 11:34Negin Farsad?

  Oh, got it, yep.

• 11:34Neil deGrasse Tyson?

  So, you keep turning it up, if you could, it would then glow white hot, then blue hot.

• 11:39Speaker 02

  Like a welding torch?

• 11:40Neil deGrasse Tyson?

  Right, but then that's all you can see, but it'll keep, what's beyond violet?

• 11:46Speaker 02

  Ultra.

• 11:46Negin Farsad?

  Ultraviolet, ultraviolet, ultraviolet, yep, you got it.

• 11:49Speaker 02

  And now you're getting your sunburns.

• 11:52Neil deGrasse Tyson?

  Yeah, and so, at a billion degrees, you are way...

• 11:55Speaker 02

  You're way off into the X and gamma ray.

• 11:57Neil deGrasse Tyson?

  X-rays and gamma rays.

• 11:58Speaker 02

  So, you don't want to be too close to one of these.

• 12:00Neil deGrasse Tyson?

  Okay, so hence the word "active," in active galactic nuclei.

• 12:03Speaker 02

  So, these objects are literally the brightest objects in the universe, and so we can see them across the universe, out to, you know, 95% of the distance to the back, when you're looking across the universe, you're looking back in time, so 95% of the distance back to the Big Bang, we can see these things.

• 12:26Negin Farsad?

  Showoffs.

• 12:27Speaker 02

  Totally.

• 12:28Negin Farsad?

  The showoffs of the, of the milk galaxy.

• 12:31Speaker 02

  Of the universe.

• 12:32Negin Farsad?

  Of the universe.

• 12:33Speaker 02

  The Milky Way does have a very massive, supermassive black hole in its center, but it doesn't get a lot to eat, so it's kind of a wimpy, dim little thing.

• 12:44Neil deGrasse Tyson?

  But back then, were we that?

• 12:46Speaker 02

  Were we ever a quasar? There is actually evidence that quite recently, like just five million years or so ago, there was a much brighter outburst from our own galactic black hole. And there's now a shockwave like running out of the galaxy.

• 13:03Neil deGrasse Tyson?

  That's how you trace it, I guess.

• 13:04Speaker 02

  Yeah. It was first discovered using the Fermi gamma ray satellite.

• 13:09Neil deGrasse Tyson?

  Yeah, but, but do, is our black hole big? Do we have black hole envy here?

• 13:12Speaker 02

  Oh, yes. We only have a million solar masses. The biggest quasars can be a billion solar masses, a thousand times bigger.

• 13:20Negin Farsad?

  So. Yeah, it's embarrassing because like, once you go big black hole, you really don't go back. And that's like something that every astrophysicist says.

• 13:29Speaker 02

  That's right. Black holes do not give up mass easily. Putting them on a diet takes a very, very, very long time.

• 13:37Negin Farsad?

  Wait, can you do, can you tell me the size of these black holes in like the big, like continental United States analogy?

• 13:44Neil deGrasse Tyson?

  Oh, yeah, sure, sure.

• 13:45Speaker 02

  So, a billion solar mass black hole.

• 13:48Neil deGrasse Tyson?

  That's like the solar system, right?

• 13:49Speaker 02

  Is a little smaller than the solar system. A stellar mass black hole, like one solar mass, is, I want to say a kilometer or so?

• 14:00Neil deGrasse Tyson?

  Yeah, I think that's right.

• 14:02Speaker 02

  Yeah. A mile. A mile.

• 14:05Negin Farsad?

  Got it.

• 14:05Speaker 02

  It's not as big as Central Park.

• 14:07Negin Farsad?

  Okay.

• 14:07Neil deGrasse Tyson?

  Yeah, and if Earth were a black hole, which it would never be, but if it were, it would be the size of a plum.

• 14:12Speaker 02

  A marble.

• 14:12Negin Farsad?

  Oh, gosh, you're busy. So compressed.

• 14:15Neil deGrasse Tyson?

  Yeah, yeah, yeah, so compressed. But, but while this whole system is big, that's tiny compared to the whole galaxy. And gas clouds are way bigger than that.

• 14:22Speaker 02

  Oh, so much bigger.

• 14:24Neil deGrasse Tyson?

  When you talk about funneling them down to something as small as the size of our solar system.

• 14:28Speaker 02

  I mean, your average gas cloud is, let's say, a million times as big as the distance from the Earth to the Sun.

• 14:37Neil deGrasse Tyson?

  Space is big, big.

• 14:38Negin Farsad?

  Yeah, space is like, like angeringly huge.

• 14:42Speaker 02

  Well, some people could think that they'd like their space.

• 14:59Neil deGrasse Tyson?

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• 15:47Neil deGrasse Tyson?

  You have not stopped there, of course. You have explored the formation of planets in these environments.

• 15:56Speaker 02

  So I started out by working on the formation of planets around normal, boring stars. And I went so far as to...

• 16:05Neil deGrasse Tyson?

  Isn't that what we all care about?

• 16:06Speaker 02

  Well, I would think so, but you're bringing up weird planets.

• 16:09Neil deGrasse Tyson?

  Okay.

• 16:10Speaker 02

  Okay. So I started out just thinking about the thing we care about. How did the Earth form? And I went so far as to hire a postdoc, Vladimir Lyra, to study this with me. And we were going along, perfectly happy, studying planets moving around in the protosolar disk. And he made the mistake, or maybe the very wise decision, to talk to some of our City University, CUNY colleagues, who were doing research here on AGNs.

• 16:42Neil deGrasse Tyson?

  Oh, okay.

• 16:43Speaker 02

  Okay. On the disks.

• 16:45Neil deGrasse Tyson?

  Because we have here in our department, we have many frequent visitors from nearby universities with resident interests.

• 16:53Speaker 02

  In particular, we have an NSF-funded partnership with CUNY...

• 16:58Neil deGrasse Tyson?

  It's official. NSF official.

• 17:00Speaker 02

  NSF official, to bring students and faculty from campuses across the city to do research here at the research-intensive American Museum of Natural History.

• 17:11Neil deGrasse Tyson?

  Is that what pays for the pizza every Thursday? Seven boxes of pizza come in.

• 17:18Neil deGrasse Tyson?

  People only think when we're eating.

• 17:21Negin Farsad?

  Yeah, what's the favorite topping of the astrophysicist community? Is there like a way?

• 17:28Speaker 02

  I believe we may ensure that all diets have an option.

• 17:32Negin Farsad?

  Okay, yeah.

• 17:33Speaker 02

  Okay, but back to AGMs, which are kind of like pizzas because they have discs, very flat distributions of gas and dust around them. Because stuff falling onto an object, if that stuff can cool off, like gas can radiate and cool off, it will form not a ball around it, but a flat disk. Same thing happened in our solar system.

• 17:54Neil deGrasse Tyson?

  As a rotating disk.

• 17:55Speaker 02

  It's a rotating disk, not like a pizza, but like a pizza being made.

• 18:00Negin Farsad?

  Or like a sushi conveyor belt.

• 18:03Speaker 02

  Hmm, let's stick with the pizza being made.

• 18:08Neil deGrasse Tyson?

  I hate those because that means the sushi went in front of the nose and mouth of other people.

• 18:12Negin Farsad?

  Other people, yeah.

• 18:13Neil deGrasse Tyson?

  I don't know something about that.

• 18:14Speaker 02

  Big Japanese scandal.

• 18:17Speaker 02

  So you've got this flat disk, and there's stuff accumulating in the disk. It gets dirty and dusty, and that dust starts to stick together. And, well, if you're in a normal disk around a normal star like the sun, which isn't quite normal, it's bigger than average, there it makes planets, like, say, this one that I can observe under my feet. However, if you're in a disk around a supermassive black hole, a hundred million times as massive as the sun, there's an awful lot of dust in that disk, and it's awful large, and you don't form three planets or eight planets. You form a million planets!

• 19:01Neil deGrasse Tyson?

  So you made a million planet star system.

• 19:05Speaker 02

  Planetary system.

• 19:06Neil deGrasse Tyson?

  Planetary system.

• 19:07Speaker 02

  Planetary system. Around a black hole. And this was a paper that we just had accepted a couple, like, two weeks ago.

• 19:15Negin Farsad?

  Oh my god, breaking news!

• 19:17Speaker 02

  Yep.

• 19:17Negin Farsad?

  Okay.

• 19:18Speaker 02

  Although I will say, so Bu Prender Mishra was the lead author on that.

• 19:23Neil deGrasse Tyson?

  How many authors are there?

• 19:24Speaker 02

  Uh, let's see, I think there are six.

• 19:26Neil deGrasse Tyson?

  So this is typical when you have collaborations.

• 19:29Speaker 02

  Absolutely.

• 19:29Neil deGrasse Tyson?

  And some of them are CUNY professors as well.

• 19:32Speaker 02

  Some of them are CUNY, Barry McKernan.

• 19:34Neil deGrasse Tyson?

  University of New York.

• 19:35Speaker 02

  Yeah, Barry McKernan and Savik Ford, Vladimir Lyra, who was a postdoc but now is a professor.

• 19:40Neil deGrasse Tyson?

  Savik Ford is named for a character on Star Trek.

• 19:42Speaker 02

  Well, she named herself for it.

• 19:45Negin Farsad?

  I was gonna say, wow, her parents really figured that out.

• 19:48Speaker 02

  No, no.

• 19:49Neil deGrasse Tyson?

  Parents, no, she did. But I think it's official, I mean, I think it's official.

• 19:51Speaker 02

  Oh yeah, she publishes under that.

• 19:53Negin Farsad?

  She's committed, okay.

• 19:55Speaker 02

  K E Savic.

• 19:55Neil deGrasse Tyson?

  Savic, yes, okay.

• 19:57Speaker 02

  Anyway, we showed that if you take standard planet formation theory, and this is the same trick that Claude Berry and Savic did 15 years ago to realize that black holes could move around like planets. If you take standard planet formation theory and apply it to the dust, you find that it is very liable to go through all the stages that you would go through to make planets, except they're really big planets, because there's so much dust.

• 20:26Neil deGrasse Tyson?

  So how big, how big are the solid planets?

• 20:28Speaker 02

  Jupiter mass, solid rock planets, except they're probably not rock, because they're probably degenerate in the centers.

• 20:36Neil deGrasse Tyson?

  So, so our Jupiter is big, but it's mostly gas?

• 20:38Speaker 02

  It's mostly gas.

• 20:39Neil deGrasse Tyson?

  You can make a Jupiter-sized planet that's rocky?

• 20:41Speaker 02

  Out of silicates.

• 20:42Neil deGrasse Tyson?

  Ooh, ouch.

• 20:44Negin Farsad?

  So, does that mean also that its gravity is like extra annoying?

• 20:49Speaker 02

  Yes.

• 20:49Negin Farsad?

  Got it. Extra annoying being like, strong.

• 20:52Neil deGrasse Tyson?

  Yeah, yeah, no, we followed that.

• 20:54Speaker 02

  I understood that.

• 20:54Neil deGrasse Tyson?

  Yeah, we totally understood you again.

• 20:56Speaker 02

  Totally.

• 20:57Negin Farsad?

  You're so perfect, I just need to like, translate for this astrophysics.

• 21:00Speaker 02

  Right, because the gravity at the cloud tops of Jupiter, we won't call it the surface, but at the cloud tops of Jupiter is quite reasonable. It's not far off from Earth's gravity.

• 21:10Neil deGrasse Tyson?

  It was like 10 times gravity.

• 21:11Speaker 02

  No, no, no, no, no.

• 21:12Neil deGrasse Tyson?

  Not even?

• 21:13Speaker 02

  Not even. It's close to Earth's gravity, because Jupiter's so big and low density. But the gravity at the surface of one of these monsters would perhaps be 10 times Earth's gravity. I don't know, I haven't done the calculation.

• 21:25Neil deGrasse Tyson?

  It's an easy calculation.

• 21:27Speaker 02

  But you're very, you're, you're the same density and, you know, 10 times the radius.

• 21:32Neil deGrasse Tyson?

  We don't expect to find life on any of these, because there's no home star to give Uh, nourishing energy to-

• 21:40Speaker 02

  No, it's rather worse. There's a home center of the accretion disk glowing in X-rays and gamma rays. It will provide plenty of energy, but it might not be in a form conducive to life as we know it.

• 21:53Neil deGrasse Tyson?

  Hostile to biology.

• 21:55Speaker 02

  That would be my suspicion.

• 21:57Negin Farsad?

  Is there a biology that we don't know of that could maybe handle it?

• 22:01Speaker 02

  That is an excellent question that we don't know the answer to.

• 22:03Neil deGrasse Tyson?

  No, no, there is. The Hulk biology.

• 22:05Negin Farsad?

  Yeah, yeah, yeah, there it is.

• 22:07Speaker 02

  The gamma ray biology, yes.

• 22:08Negin Farsad?

  Can you add the Hulk into your simulator and see what happens?

• 22:14Speaker 02

  We're gonna have to get his specifications.

• 22:17Negin Farsad?

  Yeah, yeah. I wanna see this.

• 22:18Neil deGrasse Tyson?

  So if all you need is dust, which are the larger molecules, a larger gathering of atoms-

• 22:25Speaker 02

  Minerals.

• 22:26Neil deGrasse Tyson?

  Okay.

• 22:26Speaker 02

  These are silicates. These are dust like, kinda like we find on the earth, except it formed in space. Even though space is, as noted, very large, the rocky atoms of silicon and oxygen and magnesium tend to find each other, and once they find each other, they stick together. And so they form little tiny dust grains, like a nanometer in size in deep space. But when you collect all of them together, whether it be in a protostellar disk or a supermassive black hole disk, um, they can find each other and stick together. And actually, that's something else I've been working on recently, is showing that they might be a lot stickier than people have thought.

• 23:05Neil deGrasse Tyson?

  So when they stick together, they stay?

• 23:07Speaker 02

  They appear to stay, well, until they get big enough, and then they break apart when they slam into each other. And that's actually a-

• 23:14Neil deGrasse Tyson?

  That's a whole other process.

• 23:16Speaker 02

  That's a big question in planet formation theory is, how do you get them to stop beating each other up and fragmenting?

• 23:22Negin Farsad?

  Yeah, cuz is it also, I mean, partially what you're describing almost sounds like a sandcastle, like they're sort of sticking together like a sandcastle.

• 23:30Speaker 02

  That is an excellent description of an asteroid. We call them rubble piles, but it's really a sandcastle.

• 23:35Negin Farsad?

  But it's so that it's, so they're pretty vulnerable, yeah.

• 23:39Speaker 02

  They're totally fragile. How did we learn this? Back, oh, uh, thirty years ago, a comet swung too close to-

• 23:47Speaker 02

  Comet Shoemaker Levy nine, you're supposed to not just make faces.

• 23:54Neil deGrasse Tyson?

  This is the first ever observation of a comet slamming into one of our own planets.

• 23:59Speaker 02

  Yes.

• 24:00Neil deGrasse Tyson?

  Yes.

• 24:00Negin Farsad?

  Or do you memorize all of the comets?

• 24:02Speaker 02

  No.

• 24:03Negin Farsad?

  Just the like popular ones, okay, got you.

• 24:06Neil deGrasse Tyson?

  Just the popular ones.

• 24:06Negin Farsad?

  Cause I was very impressed if you had them all down, alright.

• 24:09Speaker 02

  No, no, no, there are thousands and thousands.

• 24:11Negin Farsad?

  I am no longer impressed, go ahead.

• 24:13Speaker 02

  Very good, act as you were.

• 24:16Neil deGrasse Tyson?

  And I have to just put in here, that duo, by the way, the Shoemaker Levy nine, okay?

• 24:22Speaker 02

  It's really Shoemaker Shoemaker Levy.

• 24:24Negin Farsad?

  Was there eight other ones?

• 24:25Neil deGrasse Tyson?

  Others that they're active bunch.

• 24:28Speaker 02

  Oh yeah.

• 24:29Neil deGrasse Tyson?

  And that collaboration had a leftover asteroid that they named in my honor.

• 24:36Negin Farsad?

  Oh.

• 24:37Neil deGrasse Tyson?

  Yes.

• 24:38Speaker 02

  Okay, I knew you had an asteroid, I didn't know it was a Shoemaker Levy asteroid.

• 24:41Neil deGrasse Tyson?

  Shoemaker Levy, and the plaque is right up there on the, on the, on.

• 24:45Negin Farsad?

  Sorry, quick question, who decides these things? Is it you?

• 24:50Neil deGrasse Tyson?

  The discoverer, but it has to be approved.

• 24:53Negin Farsad?

  Okay, yeah, yeah, yeah.

• 24:54Speaker 02

  He can't be rude.

• 24:56Neil deGrasse Tyson?

  So it was that, that duo, that's how, that's how.

• 24:59Speaker 02

  Trio.

• 24:59Neil deGrasse Tyson?

  Trio, that's how fertile a discovery, a group that, Gene Shoemaker, Carolyn Shoemaker and.

• 25:06Speaker 02

  David Levy.

• 25:06Neil deGrasse Tyson?

  And David Levy.

• 25:07Speaker 02

  Yeah.

• 25:07Neil deGrasse Tyson?

  They've discovered comets and asteroids and all the kind of things.

• 25:10Speaker 02

  And Gene Shoemaker also in, pretty much was the originator of the theory of craters. Like, what happens when something, a big rock slams into a planet? It makes a crater. He described how. And so that's.

• 25:24Neil deGrasse Tyson?

  It sounds obvious.

• 25:25Negin Farsad?

  I know, I was just gonna say, like, I can also ask my seven-year-old daughter about the theory of craters, I think she'd come up with the same thing.

• 25:32Speaker 02

  That's how, that's how fundamental his work was. Because before Gene Shoemaker, people looked at the moon and saw volcano craters.

• 25:42Negin Farsad?

  Right.

• 25:43Speaker 02

  Not.

• 25:44Negin Farsad?

  Not, not, okay.

• 25:45Neil deGrasse Tyson?

  Every crater was a volcanic caldera.

• 25:48Negin Farsad?

  Yeah.

• 25:49Speaker 02

  Like Crater Lake.

• 25:50Neil deGrasse Tyson?

  They're not completely crazy to think so.

• 25:53Speaker 02

  Well, Crater Lake is a volcanic caldera.

• 25:56Neil deGrasse Tyson?

  Right, they're not crazy to think so.

• 25:58Speaker 02

  They were just wrong.

• 26:01Neil deGrasse Tyson?

  It's possible to be, that makes complete sense, you're just wrong, okay? That happens in science all the time. It's very frustrating. But the reason is, the argument against them being asteroids, was every crater is a perfect circle on the moon. And no one is thinking asteroids are coming straight in. Surely some are coming at an angle. If you're coming at an angle, you'd expect an oval.

• 26:27Negin Farsad?

  Right.

• 26:27Neil deGrasse Tyson?

  Most of them should be ovals, but every one was a perfect circle. And so that's the tension between the two arguments and the two camps. And it wasn't until we had, like, we can model.

• 26:39Speaker 02

  Well, until Gene Shoemaker came along and said, no, they should be circles.

• 26:42Neil deGrasse Tyson?

  No, no, someone had to demonstrate on a computer, with a computer simulation, that a high-speed impact, when it hits, it explodes.

• 26:51Speaker 02

  It vaporizes.

• 26:52Neil deGrasse Tyson?

  Yeah, but that explosion makes a perfect circle, even if it comes in at an angle.

• 26:57Speaker 02

  Okay, but we're off the topic.

• 26:59Neil deGrasse Tyson?

  Yes.

• 26:59Speaker 02

  Which is that when Comet Shoemaker-Levy 9 passed close to Jupiter, it felt gravitational forces from Jupiter. But it was coming by at a fair distance, and those gravitational forces were not strong, massive planet gravitational forces. They were forces equivalent to one-eighth of an inch of water in Earth's gravity. How much pressure does that put on your plate? Not much. That's all the force that tore that comet apart into 21 pieces. That's how weakly bound it was, and that's why I say it was...

• 27:36Negin Farsad?

  Because sandcastle.

• 27:37Speaker 02

  Your sandcastle is exactly right.

• 27:38Negin Farsad?

  Oh, I feel so smart right now.

• 27:40Neil deGrasse Tyson?

  It's so validated.

• 27:41Negin Farsad?

  Yes, I love this moment.

• 27:43Speaker 02

  You're welcome.

• 27:44Neil deGrasse Tyson?

  Yeah, and so just to show, there's still a huge frontier for us to understand these objects.

• 27:49Negin Farsad?

  Yeah.

• 27:49Neil deGrasse Tyson?

  And you got people, good people, working on it.

• 27:52Negin Farsad?

  Including the guy that said, when a thing hits another thing, it forms a crater.

• 27:57Neil deGrasse Tyson?

  Yes.

• 27:58Speaker 02

  Yes.

• 27:58Negin Farsad?

  Which like, I can't believe somebody, yeah, somebody had to do it first, bless that guy.

• 28:03Neil deGrasse Tyson?

  Yeah, yeah. So we got questions from our audience, who've been specifically... Clued to your research profile.

• 28:10Speaker 02

  Okay.

• 28:10Neil deGrasse Tyson?

  And the questions will emanate from that. So what do you have here for us, Nagy? I haven't seen the question. You haven't seen them either.

• 28:15Speaker 02

  I have not seen them.

• 28:16Negin Farsad?

  And I've seen them. I think they're great. Here we go. Tatiana here, from Ottawa, Ontario. I'm 15 years old and finally asking my first StarTalk question.

• 28:27Speaker 02

  Congratulations.

• 28:29Negin Farsad?

  My question is, what are and how do supersonic turbulent flows and magnetic fields regulate star formation inside molecular clouds?

• 28:40Speaker 02

  How many hours do I get?

• 28:41Negin Farsad?

  And then she's not done. Do they work together to stabilize the process? Or does their interaction create chaos?

• 28:50Speaker 02

  Yes, yes, and yes.

• 28:51Neil deGrasse Tyson?

  Yeah, naively it feels like that would just mess up the whole thing.

• 28:55Speaker 02

  Absolutely.

• 28:55Neil deGrasse Tyson?

  You're getting coherent planets out of this, aren't you?

• 28:58Speaker 02

  Stars.

• 28:59Neil deGrasse Tyson?

  Stars.

• 29:00Speaker 02

  Stars.

• 29:00Neil deGrasse Tyson?

  Okay.

• 29:01Speaker 02

  Okay. Yes, the turbulence stirs things up. And it also squeezes some of the gas. And so the squeezed gas, gravity can take hold and start the collapse process. But the stirring prevents more gas from getting grabbed by gravity and collapse down to form stars. So it's both, both and. The stirring actually wins, so the more turbulence you have, the less star formation you have.

• 29:30Neil deGrasse Tyson?

  Okay, but when, when you have a little pocket that's slightly more dense, that attracts more material that makes it even more dense. And so it's a runaway.

• 29:38Speaker 02

  It's a runaway.

• 29:39Neil deGrasse Tyson?

  Once you, once you.

• 29:40Speaker 02

  Once you get started.

• 29:41Neil deGrasse Tyson?

  Once you get out of the starting gates.

• 29:42Speaker 02

  Yes.

• 29:42Neil deGrasse Tyson?

  Okay.

• 29:43Speaker 02

  Now, then what happens is that as you start forming stars, the biggest, most massive of them pump huge amounts of energy back into the gas, whether it be through jets or ionizing radiation, or stellar winds, or ultimately supernova explosions. And that chases the gas away, and then you don't get any more star formation.

• 30:07Neil deGrasse Tyson?

  Okay, now how do you know all this?

• 30:08Speaker 02

  Uh, because I've done simulations of it. And then I compared those simulations to what observers saw.

• 30:16Neil deGrasse Tyson?

  Cause you have nothing to compare to.

• 30:18Speaker 02

  And they weren't so bad.

• 30:20Neil deGrasse Tyson?

  So if you didn't have observations to compare it to, you're just kinda presuming your results are real?

• 30:26Speaker 02

  I'm playing in the sandbox without any constraints.

• 30:29Neil deGrasse Tyson?

  Oh.

• 30:30Speaker 02

  And then I can make...

• 30:32Neil deGrasse Tyson?

  More sandbox analogy here.

• 30:34Speaker 02

  Yeah, I'm running with it here.

• 30:36Negin Farsad?

  Do you, but you, like, so how much, like, what level of confidence percentage-wise is it?

• 30:41Speaker 02

  Okay, so, okay, so the, the, the point about constraints is important. Because otherwise, someone else can come along and say, "No, no, no, no, no. The magnetic fields are gonna hold everything up. And you're gonna have to wait for the neutral atoms to drift through the ions to ever, ever make a star." Without observations, we can't tell who's right.

• 31:02Neil deGrasse Tyson?

  Mm-hmm.

• 31:02Speaker 02

  Cause he can say, "Of course it works like this. I've written 20 papers on it." And I can say, "But my programs don't show that." But, well, you know, so I wrote my programs wrong.

• 31:13Neil deGrasse Tyson?

  One possible, um, you just went too quickly past that.

• 31:17Speaker 02

  I'm sorry.

• 31:18Neil deGrasse Tyson?

  What you just said was that your, your naysayer could be right. And maybe you, your, your software had bugs in it.

• 31:27Speaker 02

  No, approximations. Approximations.

• 31:30Neil deGrasse Tyson?

  Okay.

• 31:31Speaker 02

  We always, every model has approximations.

• 31:33Neil deGrasse Tyson?

  We don't know until...

• 31:35Speaker 02

  Until you compare to the observations.

• 31:37Neil deGrasse Tyson?

  There you go, okay. And...

• 31:39Negin Farsad?

  And then you get a reasonable level of confidence in it.

• 31:43Speaker 02

  Then you, then you build up your, your confidence. And of course, then you argue about what the observations mean. And whether there was noise in the telescope. And, you know, what assumptions went into the interpretation of the observations. But ultimately, this is how science progresses. You come up with an idea, and then you have to, then other people come up with different ideas. You argue about it. And you settle it by reference to the real world.

• 32:07Negin Farsad?

  A duel, oh, not a duel. Okay, sorry.

• 32:10Speaker 02

  We try to avoid that and most of the time we succeed.

• 32:14Neil deGrasse Tyson?

  Somebody shot him in the buttocks. But, but it's evidence that arriving at what is objectively true in the actual universe is messy.

• 32:24Speaker 02

  Totally. So messy.

• 32:26Neil deGrasse Tyson?

  So messy and the strength with which you argue your point ultimately is not the arbiter.

• 32:32Speaker 02

  No, unfortunately. It might be easier that way.

• 32:35Neil deGrasse Tyson?

  And it doesn't matter how articulate you are or how charismatic you are. We have the ultimate.

• 32:41Speaker 02

  Facts still have to win.

• 32:42Neil deGrasse Tyson?

  Judge, jury and executioner is nature.

• 32:44Speaker 02

  That is the agreement that people doing science have made with each other.

• 32:49Neil deGrasse Tyson?

  It's an implicit agreement.

• 32:50Speaker 02

  One hopes it's explicit, but is that we will settle our arguments ultimately by reference to reproducible experiments and observations.

• 33:02Neil deGrasse Tyson?

  Yes. So either I'm right and you're wrong, you're right and I'm wrong, or we're both wrong. It'll be decided by more data or better data.

• 33:10Speaker 02

  That's right.

• 33:11Neil deGrasse Tyson?

  Yeah, okay.

• 33:11Speaker 02

  And that, that is the, the central tenet of science.

• 33:17Neil deGrasse Tyson?

  Where does the magnetic field come from?

• 33:19Speaker 02

  The magnetic field comes from a dynamo. So dynamos happen when you get some sort of stirring of charged gas or charged things.

• 33:31Neil deGrasse Tyson?

  Oh, okay.

• 33:32Speaker 02

  So like a dynamo in a power station, the charge is running through wires.

• 33:36Neil deGrasse Tyson?

  And it's spinning.

• 33:37Speaker 02

  And it's spinning.

• 33:38Neil deGrasse Tyson?

  Yes, yes.

• 33:38Speaker 02

  And in the universe, or in, in the earth, the dynamo is turbulent swirling magma deep down in the earth that is kept molten by the pressure and radioactivity of the earth. And it swirls around and makes the earth's magnetic field and that's a dynamo. Well, same in the sun, except there it's plasma. In galaxies, the charged gas between the stars forms a dynamo stirred by supernova explosions and by gravity.

• 34:12Neil deGrasse Tyson?

  So if you didn't have the turbulence.

• 34:14Speaker 02

  You wouldn't get the dynamo.

• 34:16Neil deGrasse Tyson?

  You wouldn't have a magnetic field.

• 34:17Speaker 02

  You would not have a magnetic field.

• 34:18Neil deGrasse Tyson?

  So they go hand in hand.

• 34:19Speaker 02

  They, one is, one generates the other.

• 34:21Neil deGrasse Tyson?

  Okay.

• 34:21Negin Farsad?

  It's like they're in heat and then they give birth to this.

• 34:27Speaker 02

  Sure, maybe. I think you're stretching the field here. But if you stretch the field and twist it and rotate, you will get a dynamo.

• 34:37Negin Farsad?

  Great, thank you.

• 34:39Speaker 02

  Okay, so the first dynamos happen when the very, very first stars form. And ever since then, we've had significant magnetic fields running around, getting stretched and twisted and folded to make more magnetic fields.

• 34:55Neil deGrasse Tyson?

  There we are.

• 34:55Negin Farsad?

  There we are. Shall we move on to the next question?

• 34:58Neil deGrasse Tyson?

  Thank you for that.

• 34:58Negin Farsad?

  All right. Ismael Valdez here, asking my first question from Vina del Mar, Chile. Okay.

• 35:05Speaker 02

  Okay.

• 35:06Negin Farsad?

  In regards to stars and gas giants, if Jupiter were sufficiently massive, would the pressure ignite, would its pressure ignite its lighter components?

• 35:17Speaker 02

  Yes.

• 35:17Negin Farsad?

  Furthermore, do the sun or stars in general share elements with gas giants, like a rocky core, or is it fused gas all the way through? Which sounds like a tough meal at Taco Bell. I don't know. Go ahead.

• 35:31Speaker 02

  Okay.

• 35:32Neil deGrasse Tyson?

  Let me modify that just a little bit. If we had the capacity to dump mass onto Jupiter,

• 35:38Speaker 02

  Sure.

• 35:38Neil deGrasse Tyson?

  could we ignite it one day?

• 35:40Speaker 02

  He had two questions. First question is, if you increase Jupiter's mass, does it ignite? And the answer is yes. If you increase Jupiter's mass enough, like, well, if you get it up to about, I want to say 10 times the mass of Jupiter, you get the deuterium burning, the heavy hydrogen with extra neutrons. And that lasts for a little while, but there's not a whole lot of deuterium in the universe. It's like, I don't know, a part in 100,000, a few parts in 100,000. So that's, you get a little flash of light, you know, for a couple of, maybe a million, a couple hundred thousand years, and then it's gone. And that's a brown dwarf.

• 36:24Speaker 02

  And they exist, and we've got one of the world's premier research groups on the topic right upstairs here, run by Jackie Farady, and...

• 36:34Neil deGrasse Tyson?

  Because we just went down the hall to get Mordecai, right?

• 36:37Speaker 02

  Yeah, yeah, yeah. I traveled a long way. I want my per diem.

• 36:41Neil deGrasse Tyson?

  In the Department of Astrophysics of the American Museum of Natural History.

• 36:46Speaker 02

  That's a brown dwarf. Now, if you keep piling mass on and get up to ba ba ba ba ba ba in Jupiter masses, um... Like eighty times.

• 36:56Neil deGrasse Tyson?

  Oh, that ma- that much?

• 36:57Speaker 02

  Yeah, eighty times the mass of Jupiter.

• 36:59Neil deGrasse Tyson?

  That's a lot.

• 37:00Speaker 02

  Which is a little under a tenth of the mass of the sun.

• 37:04Neil deGrasse Tyson?

  You could just drop Saturn onto it.

• 37:05Speaker 02

  No, not not.

• 37:05Neil deGrasse Tyson?

  That would be amazing to watch.

• 37:07Speaker 02

  But not nearly enough.

• 37:08Neil deGrasse Tyson?

  That still wouldn't ignite it.

• 37:09Speaker 02

  No, no, no, not even close.

• 37:10Neil deGrasse Tyson?

  Not even close.

• 37:10Speaker 02

  Not even close.

• 37:11Negin Farsad?

  Well, so you, as you said earlier, like, something like that is just like a couple hundred thousand years. It's like dumb.

• 37:18Speaker 02

  That's what, that's the brown dwarf. Don't call brown dwarfs dumb around here.

• 37:22Negin Farsad?

  Okay, no, I'm just trying to understand, because you made that sound like not nothing, like it was.

• 37:26Speaker 02

  It's not nothing, it's fusion, but it's not a lot of fusion.

• 37:29Negin Farsad?

  Okay.

• 37:30Neil deGrasse Tyson?

  Even what he's about to say.

• 37:31Speaker 02

  Wait, wait, wait, wait.

• 37:32Neil deGrasse Tyson?

  That's a.

• 37:32Negin Farsad?

  That's okay.

• 37:33Speaker 02

  It's a flash in the pan.

• 37:34Negin Farsad?

  Got you.

• 37:34Speaker 02

  Okay, but if you get up to eighty times, then you can ignite hydrogen. And there's a lot more hydrogen, that's what Jupiter's mostly made of. Then you've got a very low mass star. And very low mass stars sit there and simmer for longer than the current lifetime of the universe. So that will keep going and going and going.

• 37:55Negin Farsad?

  So that's way more than two hundred thousand.

• 37:57Speaker 02

  It's way more than the life of the universe. It's like ten times the life of the universe. No, a hundred times the life, current life of the universe.

• 38:03Neil deGrasse Tyson?

  Yeah, but, but question. Right now Jupiter has a rocky core.

• 38:07Speaker 02

  Yes.

• 38:08Neil deGrasse Tyson?

  What happens to that rocky core? Because it's kind of related to this question.

• 38:11Speaker 02

  Absolutely, yes, yes, let's go. Let's go, let's go.

• 38:15Neil deGrasse Tyson?

  Bring it on.

• 38:15Speaker 02

  Okay, so what happens is, it gets completely overwhelmed by all the hydrogen and just gets mixed in, uh, because the hydrogen is sitting there fusing. So you have a little tiny rocky core. Now the sun, of course.

• 38:27Neil deGrasse Tyson?

  Why doesn't it just vaporize the rocky core?

• 38:29Speaker 02

  Yeah, that's what I'm saying. Okay, it's not rocky anymore, but it is, the elements of the former, of the rock, uh, core formerly known as rocky are now part of the fusing vaporized hydrogen in the center of the object. Because it's now, you know, far hotter than anything, any rock has any right to withstand. So it's vape, it's rock vapor.

• 38:50Neil deGrasse Tyson?

  It vaporized all the rock, got you.

• 38:51Speaker 02

  That's right. Um, now remember, the sun also has silicon and magnesium and aluminum and oxygen in it. It's just all mixed in with the hydrogen.

• 39:00Neil deGrasse Tyson?

  Right. So, you know, the sun, you might think would have a rocky core the way Jupiter did, but for that same reason, it's all

• 39:06Speaker 02

  It's too hot.

• 39:07Neil deGrasse Tyson?

  It can't be anything other than

• 39:09Negin Farsad?

  Plasmas.

• 39:10Speaker 02

  It lose ions and electrons even. Can't even be atoms, except on the very, very surface.

• 39:16Neil deGrasse Tyson?

  An atom is a nucleus plus electrons.

• 39:18Speaker 02

  Yes.

• 39:18Neil deGrasse Tyson?

  All the electrons are gone.

• 39:19Speaker 02

  Yes.

• 39:19Neil deGrasse Tyson?

  Yeah.

• 39:20Speaker 02

  In the center, they're all gone. They're just roaming freely away from their parent atoms.

• 39:25Negin Farsad?

  Got it.

• 39:25Speaker 02

  Here's your cue.

• 39:26Negin Farsad?

  Yeah.

• 39:29Negin Farsad?

  They're having a rebellious phase.

• 39:31Speaker 02

  Oh, they are long gone, never to return.

• 39:34Negin Farsad?

  Never to return. They're not just like TP'ing their geometry teacher's house or something.

• 39:38Speaker 02

  No, no, no.

• 39:39Negin Farsad?

  Okay.

• 39:39Speaker 02

  They have gone.

• 39:40Neil deGrasse Tyson?

  That's a trip. Toilet papering. Yes. Have you done that?

• 39:45Negin Farsad?

  I have.

• 39:49Negin Farsad?

  I TP'd once in my

• 39:51Neil deGrasse Tyson?

  This is stories you tell your offspring.

• 39:54Speaker 02

  I'm afraid we didn't do that in the center of New York City because a six-story apartment building is hard to TP.

• 39:59Negin Farsad?

  You're just like doing, you're just doing toilet paper on someone's door and it's a lot less, you know.

• 40:04Speaker 02

  Satisfying.

• 40:05Negin Farsad?

  Yeah. Can't imagine.

• 40:20Speaker 03

  I'm Nicholas Costella and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 40:39Neil deGrasse Tyson?

  Time for a few more questions. What do you have?

• 40:41Negin Farsad?

  Okay, let's see. Hello. How is dark matter incorporated into your simulations? Random distribution or what?

• 40:50Speaker 02

  Okay.

• 40:51Negin Farsad?

  Oh, sorry. And this question is from Ben Grund.

• 40:54Speaker 02

  Great question. And the answer is, um, any which way I can. So sometimes we actually put in particles in the simulation and watch them roam around under the force of gravity. And, well, they're very massive particles, but they still behave like dark matter because they don't interact with the gas, except by gravity. Other times

• 41:16Neil deGrasse Tyson?

  Well, she just said, since we don't actually know what dark matter is.

• 41:19Speaker 02

  Oh, no, no, no. We're not even going there.

• 41:22Neil deGrasse Tyson?

  No, but, but you know it has gravity.

• 41:24Speaker 02

  Yes.

• 41:24Neil deGrasse Tyson?

  Your simulation has to Get it somehow. So you sprinkle in, you invent a particle that interacts only by gravity.

• 41:33Speaker 02

  Yup.

• 41:33Neil deGrasse Tyson?

  And has enough.

• 41:35Speaker 02

  Mass.

• 41:36Neil deGrasse Tyson?

  Enough gravity to match.

• 41:39Speaker 02

  The observed dark matter.

• 41:40Neil deGrasse Tyson?

  Observe dark matter. Okay.

• 41:41Speaker 02

  Yes.

• 41:42Neil deGrasse Tyson?

  So this is by, as they say, by fiat you do this. Does that?

• 41:45Speaker 02

  Uh, no. I mean, you could say.

• 41:48Negin Farsad?

  If I understood what any of these things were, I could weigh in on if you used fiat correctly.

• 41:54Speaker 02

  I wouldn't say it's by fiat in the sense that the whole simulation by that definition is by fiat.

• 41:59Neil deGrasse Tyson?

  Okay.

• 42:00Speaker 02

  Right? I've added in a field of gas. I've added in star particles. So I'm, it's just one element of the simulation.

• 42:06Neil deGrasse Tyson?

  It's a way to get a source of gravity without having to worry about it after that.

• 42:11Speaker 02

  It behaves like dark matter.

• 42:12Neil deGrasse Tyson?

  Great.

• 42:13Speaker 02

  The simpler way to do this, which I also sometimes do if I can get away with it, is to simply put in a gravitational field that reproduces the dark matter distribution and then let that handle it without having to actually do.

• 42:27Neil deGrasse Tyson?

  Track particles.

• 42:27Speaker 02

  Without having to track particles and pay attention and do accounting and get bugs and all the rest.

• 42:35Neil deGrasse Tyson?

  Alright, so is it smoothly?

• 42:37Speaker 02

  It's.

• 42:38Neil deGrasse Tyson?

  It's a smooth field.

• 42:39Speaker 02

  Well, it's smooth if you're on a subgalactic scale. But if you're on a, you know, a galaxy forming scale, it's very, very clumpy because the clumps are the galaxies. So in that sense, um, in, you know, when I'm simulating the formation of the first galaxies, um, then we're seeing big clumps of dark matter that the gas falls into and then you've got a galaxy.

• 43:06Neil deGrasse Tyson?

  So I've heard this, I think it's right, that dark matter, whatever it is, is so prevalent that when you just, when we look at and describe stars and galaxies, this is the froth on an ocean.

• 43:21Speaker 02

  Well, one-sixth of the mass of the galaxy is in anything visible. Stars, planets, gas, comets, all of that. One-sixth of the mass.

• 43:30Neil deGrasse Tyson?

  So eighty-five percent of the gravity.

• 43:32Speaker 02

  Is from dark matter.

• 43:33Neil deGrasse Tyson?

  It's something you only know what is.

• 43:36Speaker 02

  We know it exerts gravity and we know it doesn't move at light speed. That's why it's cold dark matter.

• 43:42Negin Farsad?

  Well, is there like an area like that doesn't have any, like how Wyoming doesn't have people? Like, is there an area of the galaxy where like there's no dark matter?

• 43:52Speaker 02

  Like Wyoming doesn't have people, voids don't have dark matter. While clusters have lots of dark matter.

• 43:58Negin Farsad?

  Okay.

• 43:58Speaker 02

  And filaments have, well, intermediate amounts of dark matter. They're like interstates.

• 44:03Negin Farsad?

  Okay. So yeah, it's not so evenly distributed.

• 44:07Speaker 02

  It's absolutely not evenly distributed, not in the universe.

• 44:09Neil deGrasse Tyson?

  Right.

• 44:10Speaker 02

  That's why we call it the cosmic web. Because it looks like spider webs, like with thin filaments and then big spaces in between.

• 44:18Negin Farsad?

  Right.

• 44:19Neil deGrasse Tyson?

  So web is, we'd say web now, but I remember when a cross section of a sponge. Does a sponge still work as a?

• 44:25Speaker 02

  Sponge still works, yeah.

• 44:27Neil deGrasse Tyson?

  And sort of areas around it and places where you intersect?

• 44:30Speaker 02

  These days, we usually talk about webs.

• 44:32Neil deGrasse Tyson?

  Web, okay, that's fine.

• 44:34Negin Farsad?

  Ditch the sponge.

• 44:35Neil deGrasse Tyson?

  I was kinda into sponges, though.

• 44:37Negin Farsad?

  I mean, I know, you really got into it.

• 44:38Speaker 02

  Well, that was an analogy for the interstellar medium, too.

• 44:40Neil deGrasse Tyson?

  Yeah.

• 44:41Speaker 02

  You know, Chris McKee and Don Cox arguing about, is it a sponge? Or is it little round clouds?

• 44:47Neil deGrasse Tyson?

  I had a cameo in SpongeBob.

• 44:50Neil deGrasse Tyson?

  I was Neil deBass Tyson.

• 44:52Speaker 02

  Oh.

• 44:53Neil deGrasse Tyson?

  Astrofiscesis. So I just thought, I'm sticking to sponge.

• 44:59Speaker 02

  You got it.

• 44:59Neil deGrasse Tyson?

  Okay, thank you.

• 45:00Speaker 02

  You can have the dark, the cosmological sponge.

• 45:04Neil deGrasse Tyson?

  Yes, thank you, thank you. Time for a couple more, let's keep going.

• 45:08Negin Farsad?

  Okay, let's see.

• 45:09Speaker 02

  We're on a roll here.

• 45:10Neil deGrasse Tyson?

  Yes, we are.

• 45:10Negin Farsad?

  So Gavin Bamber from North Vancouver, please visit, they add. How long does it take to form a star or a planet? Is it the same process? We're both in the same stuff.

• 45:22Speaker 02

  Ooh. Okay. I believe the answer is yes and yes. And so how long does it take to form a star? The main formation phase, when most of this stuff comes down, is maybe 100,000 years, but it trickles along.

• 45:41Neil deGrasse Tyson?

  That quickly, even?

• 45:42Speaker 02

  Yeah, that's like the main accretion phase. But it's gonna trickle along with a disk and accretion more mass and forming planets for a million, a couple of million years.

• 45:54Neil deGrasse Tyson?

  So you'll form a star before you form the planets?

• 45:57Speaker 02

  Well, that's an ongoing controversy. That was the, that was the idea, that used to be the idea.

• 46:03Neil deGrasse Tyson?

  Wouldn't that be the case, right?

• 46:04Speaker 02

  You would think. But nowadays, the more we examine the question, the faster the planets seem to form. And so now I would actually say that the first planets form during that main accretion phase, very, very fast. But then you continue to form planets and planetary-like things for several million years.

• 46:25Neil deGrasse Tyson?

  And once again, you're forming planets in a disk.

• 46:28Speaker 02

  In a disk. It's all dust and gas in a disk.

• 46:31Neil deGrasse Tyson?

  I have an accretion disk right here.

• 46:32Speaker 02

  Yeah, yeah. If you wanna get brighter, eat more. Like a quasar.

• 46:37Negin Farsad?

  That's, that takes so long. It just like, everyone has to be really committed to that planet for it to form, you know what I mean?

• 46:45Speaker 02

  Cause it takes a few million years.

• 46:46Negin Farsad?

  Oh my gosh.

• 46:47Speaker 02

  Yeah, on the other hand, where are you gonna go? You're stuck in this disk going round and round and round.

• 46:52Negin Farsad?

  Yeah, yeah, yeah, yeah. Let's get it going. Eventually we'll have an Arby's here, whatever.

• 46:57Speaker 02

  Yeah, well, now, the development of Arby's takes a lot longer. That's billions of years. Observably.

• 47:06Neil deGrasse Tyson?

  Yeah, as Carl Sagan said, how do you make an apple pie? You start with a big bang.

• 47:14Speaker 02

  Go find the chicken.

• 47:17Negin Farsad?

  Time for another question?

• 47:18Neil deGrasse Tyson?

  Yeah, let's do it.

• 47:19Negin Farsad?

  After all the model runs, how often do planets form with a satellite as large by percentage of mass of the planet as our moon?

• 47:28Neil deGrasse Tyson?

  Good one.

• 47:29Speaker 02

  That's a very good one. And the answer is that the computer simulations aren't high enough resolution to really get a good answer to that yet. And so that is a current research question.

• 47:43Negin Farsad?

  But you can't see the moons?

• 47:45Neil deGrasse Tyson?

  Yeah, but we have all these planets with wimpy moons.

• 47:48Speaker 02

  Yes.

• 47:48Neil deGrasse Tyson?

  Right?

• 47:49Speaker 02

  Yes.

• 47:49Neil deGrasse Tyson?

  So we already know.

• 47:50Speaker 02

  Well, observationally, we know in one planetary system with one set of initial conditions that moons like the Earth are pretty rare. And that's all we know. How many planetary systems do we know of?

• 48:05Neil deGrasse Tyson?

  Well, it's growing now.

• 48:06Speaker 02

  Six thousand and counting.

• 48:08Neil deGrasse Tyson?

  It's growing.

• 48:09Speaker 02

  It's growing fast and it's gonna keep growing. And we don't know if any of those planets have moons because, observationally, we haven't been able to see them because it's really hard to see a moon around a planet. It's already really, really hard to see a planet, much less a moon. David Kipping up at Columbia thinks he's found a moon, but everybody else is staying on the fence and saying, maybe it's a moon.

• 48:33Neil deGrasse Tyson?

  David Kipping, we've had him on StarTalk.

• 48:35Speaker 02

  I'm sure you have.

• 48:36Neil deGrasse Tyson?

  He's got a lab, the Cool Worlds Lab, which is kinda cool.

• 48:39Speaker 02

  And he's got a podcast.

• 48:40Neil deGrasse Tyson?

  Yes.

• 48:41Speaker 02

  Which funds that lab.

• 48:42Neil deGrasse Tyson?

  Cool Worlds.

• 48:43Negin Farsad?

  So wait, your simulations will sometimes see like a hint of a moon?

• 48:49Speaker 02

  Uh, my, well, I don't do those simulations, but our simulations, the fields, you can make moons and we know, I mean, we certainly know how to make the Earth's moon, slam a Mars-sized planet into a proto-Earth. And that works shockingly well, as evidenced by the Apollo astronauts bringing back rocks that had the same composition as the Earth because they formed from that super collision.

• 49:18Neil deGrasse Tyson?

  To begin with.

• 49:21Speaker 02

  They left from the Earth to the moon.

• 49:23Negin Farsad?

  The movie studio.

• 49:25Speaker 02

  Thank you.

• 49:28Neil deGrasse Tyson?

  But that meant that the moon didn't form organically with the Earth.

• 49:33Speaker 02

  It formed afterwards.

• 49:34Neil deGrasse Tyson?

  Afterwards.

• 49:36Speaker 02

  But now, what the Earth is made of, of course, is also a mixture of proto-Earth and I think they call it Aries, the Mars-sized object.

• 49:44Neil deGrasse Tyson?

  No, no, it's, um...

• 49:46Speaker 02

  Thea?

• 49:47Neil deGrasse Tyson?

  Uh, Thea. Thea.

• 49:48Speaker 02

  Isn't Thea the proto-Earth and Aries the proto-moon?

• 49:51Neil deGrasse Tyson?

  Oh.

• 49:52Speaker 02

  I mean, the proto-moon.

• 49:54Neil deGrasse Tyson?

  I think Thea is the proto-slammer.

• 49:56Speaker 04

  Confirming now, uh, being asked that the ancient proto-planet that we collided with was Thea.

• 50:03Speaker 02

  Okay.

• 50:03Neil deGrasse Tyson?

  So shockingly successful is this model that we even named the object that doesn't exist anymore.

• 50:09Speaker 02

  That's right.

• 50:10Negin Farsad?

  The impact object.

• 50:11Neil deGrasse Tyson?

  Object, which is obliterated.

• 50:13Speaker 02

  Yes.

• 50:13Neil deGrasse Tyson?

  And became part of the...

• 50:14Speaker 02

  However...

• 50:14Neil deGrasse Tyson?

  We gave it a name.

• 50:15Speaker 02

  Yes.

• 50:15Neil deGrasse Tyson?

  That's kind of audacious.

• 50:17Negin Farsad?

  A cool name.

• 50:18Speaker 02

  We can do those sorts of calculations for planets elsewhere, but to get the frequencies, that's going... that means a lot of calculation. We don't have enough computers to do that currently.

• 50:30Neil deGrasse Tyson?

  Well, I love me my moon, because our moon is the same size on the sky as the sun, so we get beautiful eclipses.

• 50:36Negin Farsad?

  Oh, I love it.

• 50:36Neil deGrasse Tyson?

  Nobody else has eclipses like that. At Jupiter, it's got moons, but the sun is far, the moons are small, nothing matches up.

• 50:44Negin Farsad?

  Yeah.

• 50:45Neil deGrasse Tyson?

  The way our moon and our sun... So, what is it? The moon is 400 times closer and 1/400th the size.

• 50:54Speaker 02

  Yep.

• 50:54Neil deGrasse Tyson?

  So, everything ratios exactly.

• 50:56Negin Farsad?

  Exactly to the... Yeah.

• 50:59Speaker 02

  And that's how you get eclipse chasers.

• 51:01Neil deGrasse Tyson?

  Yeah. It's the greatest spectacle of nature, a total solar eclipse.

• 51:05Negin Farsad?

  Second only to Manhattan Henge, which is also something because...

• 51:07Neil deGrasse Tyson?

  You got you some Manhattan, huh?

• 51:08Negin Farsad?

  I love a Manhattan Henge!

• 51:10Speaker 02

  Oh, my gosh!

• 51:12Negin Farsad?

  Thank you. Uh, that's because of you. Yeah, I followed your dates.

• 51:16Neil deGrasse Tyson?

  Oh, okay. So, Mordecai, time for one more question.

• 51:19Speaker 02

  Okay.

• 51:19Neil deGrasse Tyson?

  We've been going.

• 51:20Speaker 02

  It better be a good one.

• 51:22Neil deGrasse Tyson?

  And you're a good question-answser.

• 51:23Negin Farsad?

  Yes, this is great.

• 51:26Neil deGrasse Tyson?

  And efficient.

• 51:26Speaker 02

  Okay, I will ramble.

• 51:28Neil deGrasse Tyson?

  No, no!

• 51:30Speaker 02

  Lay the question on us.

• 51:32Negin Farsad?

  Here we go. From Emil Rougeau, who describes himself as a man who has forgotten what curiosity is. As once said before by you, Dr. McLough, eight to 10 years ago, quote, "We live in a time where we have understood that the universe is far stranger than we would have thought. Have these thoughts changed over the years, or have they made more problems for you?"

• 51:54Speaker 02

  Um, I would have to say that if anything, these thoughts have intensified.

• 52:00Negin Farsad?

  Okay.

• 52:01Speaker 02

  The universe is far stranger than we once thought and far stranger, possibly, than we can imagine.

• 52:10Speaker 02

  Why do I say that? Because we live in a universe that is expanding, that is accelerating, that is forming stars, planets, black holes. And it all came from a almost perfectly smooth, homogeneous, hot, very, very hot, beginning. That's not a story that someone 100 years ago would have told. None of it. So, yeah, strange.

• 52:42Neil deGrasse Tyson?

  In fact, I have books, old books, that describe the universe as an ordered, majestic place. Everything in the right spot. Everything in stately orbits surrounding. And then we found out that things slam into each other. They blow up.

• 53:00Speaker 02

  It's full of turbulence and chaos.

• 53:03Neil deGrasse Tyson?

  Yeah, I mean, it's just a mess.

• 53:05Speaker 02

  Yes. Thank you for that cogent description of the modern understanding of the universe.

• 53:11Negin Farsad?

  Wait, so can I ask you both a question then? Now, you're both in the field of trying to understand the universe better. Right? Solving mysteries.

• 53:20Neil deGrasse Tyson?

  Aren't we all, at some level, trying to understand the universe better?

• 53:23Negin Farsad?

  I guess if, like, doing a tight 10 at the Chuckle Hudson Sheboygan makes, solves the universe in any way, I might be in that business. But, um, does it make either of you feel, I don't know, bad that, like, the more you study, the, like, more you find it chaotic? I don't mean, I don't-

• 53:46Speaker 02

  Let's just say it keeps me in a job.

• 53:50Neil deGrasse Tyson?

  Oh, I have a different way to answer that.

• 53:53Negin Farsad?

  Yeah.

• 53:53Neil deGrasse Tyson?

  If the universe were more and more chaotic, requiring equally as complex laws of physics to understand it, then what are we doing? But the real majesty is that it's just a few laws of physics.

• 54:13Speaker 02

  That generate all that chaos and mess.

• 54:15Neil deGrasse Tyson?

  That generate all that chaos. It's just a few laws of particle physics that account for all the particle zoo that we know and love.

• 54:27Neil deGrasse Tyson?

  Except for dark matter, we're not there yet. So.

• 54:30Speaker 02

  But we're working on it.

• 54:31Neil deGrasse Tyson?

  If to understand the universe required a complexity of theorizing that matched it, then all bets are off. I'll just go home, you know, go to the Bahamas. Give up on it. But if foundational understanding, like Mordecai, you said all this without even mentioning that you're an expert in fluid dynamics.

• 54:53Speaker 02

  I implied it by discussing the turbulent dynamo.

• 54:56Neil deGrasse Tyson?

  Yes.

• 54:57Speaker 02

  Which is absolutely an extreme fluid dynamics problem.

• 55:01Neil deGrasse Tyson?

  Yes, but fluid.

• 55:02Speaker 02

  Magnetized fluid dynamics.

• 55:04Neil deGrasse Tyson?

  Look, he's got a face. He made a face. He was like, I'm angry. So, so fluid dynamics is the study of fluids, which can be gaseous or liquid, and.

• 55:16Speaker 02

  Kitchen sink.

• 55:17Neil deGrasse Tyson?

  There's a whole set of rules just for fluid dynamics that works.

• 55:21Speaker 02

  Yep.

• 55:21Neil deGrasse Tyson?

  In water flowing through pipes as it does.

• 55:25Speaker 02

  In stars.

• 55:27Neil deGrasse Tyson?

  In stars. So that is.

• 55:29Negin Farsad?

  Wild.

• 55:29Neil deGrasse Tyson?

  That is the majesty of the universe.

• 55:31Negin Farsad?

  Right, because you're, you're, you're settled on some, on the rules and now you're just like watching to see how these rules play out on a universe basis and it's fun.

• 55:41Neil deGrasse Tyson?

  Yes.

• 55:41Speaker 02

  Yes.

• 55:42Neil deGrasse Tyson?

  Yes.

• 55:43Speaker 02

  I get that.

• 55:44Negin Farsad?

  I get that.

• 55:44Speaker 02

  We'll go with it.

• 55:45Negin Farsad?

  That's your tight 10 at the Sheboygan chuckle hut.

• 55:48Neil deGrasse Tyson?

  I, I, I, okay.

• 55:52Speaker 02

  He hasn't spent enough time in Sheboygan. Neither have I.

• 55:56Neil deGrasse Tyson?

  Mordecai, how will quantum computing help what you're doing?

• 55:58Speaker 02

  We don't know yet.

• 56:00Neil deGrasse Tyson?

  Is there a problem that is intractable now that you think will succumb to quantum computers?

• 56:06Speaker 02

  Well, certainly problems in atomic physics, like say the million different transitions in the molecule water that all produce different amounts of radiation of different colors, different spectral lines.

• 56:21Speaker 02

  Those may well be better done by quantum computing than by the poor guy who came from banking into astrophysics and ended up having to do that for his thesis. But, um, most of the problems we have, we don't yet know how to compute on a quantum computer. Give it a hundred years.

• 56:42Negin Farsad?

  A hundred? Oh.

• 56:44Neil deGrasse Tyson?

  Or ten. I mean.

• 56:46Negin Farsad?

  Yeah, I'm like, this is...

• 56:48Speaker 02

  I mean, look.

• 56:49Neil deGrasse Tyson?

  A hundred years ago, we were only inventing quantum physics.

• 56:52Speaker 02

  Yes, we had already invented quantum physics, and we're still figuring it out.

• 56:57Neil deGrasse Tyson?

  Yes, we're still figuring it out, yeah.

• 56:58Speaker 02

  It took, when Newton wrote down his laws of gravity, it took a century before we could explain the orbit of the moon.

• 57:05Neil deGrasse Tyson?

  Yeah, yeah, okay. That's all the time we have, Negin. Thank you for asking those questions. And Mordecai, brilliant answers, right on, right on brand.

• 57:14Speaker 02

  Well.

• 57:15Neil deGrasse Tyson?

  And you have some groupies.

• 57:17Speaker 02

  Are you saying that I'm fusing here?

• 57:18Neil deGrasse Tyson?

  I'm saying, plus you had at least one groupie there who was quoting your chapter and verse from ten years ago.

• 57:24Speaker 02

  I was impressed. Thank you.

• 57:26Neil deGrasse Tyson?

  Yeah, no, we, we, our people, our people go back.

• 57:29Negin Farsad?

  Yeah, no, they're like, no things, the listeners. Yeah.

• 57:34Speaker 02

  Right audience to have.

• 57:35Neil deGrasse Tyson?

  All right, uh, thank, this might be our first interview with you.

• 57:38Speaker 02

  This is my first time in this chair.

• 57:41Neil deGrasse Tyson?

  In that chair, but not your first time in my office.

• 57:43Speaker 02

  Not the first time in my, in this office.

• 57:46Neil deGrasse Tyson?

  He works just down the hall. All right. Negin, not your first rodeo here.

• 57:50Negin Farsad?

  No, my first time.

• 57:51Neil deGrasse Tyson?

  And look forward to your next time joining us.

• 57:52Negin Farsad?

  Ah, such a great time. Thanks for having me.

• 57:55Neil deGrasse Tyson?

  We'll find you on Wait, Wait, Don't Tell Me.

• 57:56Negin Farsad?

  If I'm in Wait, Wait, Don't Tell Me, if you're in Chattanooga, Tennessee, on June 24th, you can find me there too at the Comedy Cat.

• 58:01Neil deGrasse Tyson?

  Oh, Chattanooga, Tennessee. We'll look for you. Uh, and that's, uh, June 24th.

• 58:07Negin Farsad?

  June 24th, I'll be doing The Muslims Are Coming with Equally Threatening Friends, a night of stand-up comedy.

• 58:16Neil deGrasse Tyson?

  Okay.

• 58:19Neil deGrasse Tyson?

  Will that attract people or scare people away? If no one shows up in Chattanooga, Tennessee.

• 58:25Negin Farsad?

  I need Dr. Maclow to do a simulation and see what happens.

• 58:31Neil deGrasse Tyson?

  That's all the time we have. So again, Mordecai, thank you.

• 58:34Speaker 02

  You're very welcome.

• 58:35Neil deGrasse Tyson?

  Thank you.

• 58:35Speaker 02

  Great fun to be here.

• 58:36Neil deGrasse Tyson?

  This has been StarTalk: Cosmic Queries on the Formation of Planets with my friend and colleague, Mordecai Maclow. Until next time, keep looking up.