Cosmic Queries – The 30-Second Universe

Neil deGrasse Tyson, co-host Chuck Nice, and astrophysicist and StarTalk geek-in-chief Charles Liu, PhD answer fan-submitted questions on gravity, asteroids, AI, spacetime, and more to celebrate the release of Charles’ new book “30-Second Universe.” NOTE: StarTalk+ Patrons and All-Access subscribers can watch or listen to this entire episode commercial-free here: https://www.startalkradio.net/show/cosmic-queries-the-30-second-universe/ Thanks to this week’s Patrons for supporting us: Jim Brown, Christopher MacCay, Carlene Goodbody, Ernesto Chavez, Doug Sherman

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

• 0:00Neil deGrasse Tyson?

  From the American Museum of Natural History in New York City, and beaming out across all of space and time, this is StarTalk, where science and pop culture collide.

• 0:22Neil deGrasse Tyson?

  This is StarTalk. I'm Neil deGrasse Tyson, your personal astrophysicist, coming to you from my office at the Hayden Planetarium, right here in New York City. I got Chuck Nice, Chuck! Hey, what's happening, Neil? You're my man. That's right. Tweeting a Chuck Nice comic. Thank you, sir. And I went over another Chuck. You're also a Chuck. I can be a Chuck. We call you Charles, but in your day, you were Chuck. Yes. I ain't calling you Chuck because that's my Chuck. Fair enough. All right. I got Charles Liu on the line here because he just published a book. Except he doesn't have the book for me to show. How do you like that? Charles, the name of your book?

• 1:01Charles Liu?

  Yes, it is 30 Second Universe.

• 1:04Neil deGrasse Tyson?

  Wait, you know 31 other universes? The 30-second universe?

• 1:08Charles Liu?

  It would be nice. I would enjoy that. There's the Marvel Cinematic Universe, there's the Marvel Regular Universe, the D.C. Universe.

• 1:15Neil deGrasse Tyson?

  You had an answer to that.

• 1:16Charles Liu?

  Well, no, no. Look, thank you so much.

• 1:18Neil deGrasse Tyson?

  There's the Hundred Acre Wood. That's right. There's all these universes. All these universes. Where the laws of physics are not quite all there. Nice.

• 1:27Charles Liu?

  But it's very nice. And yes, this book is out, and I'm very, very lucky. Ivy Press.

• 1:33Neil deGrasse Tyson?

  Ivy Press, good.

• 1:34Charles Liu?

  Yes. And let me shout out, give a shout out to my co-authors as well, Karen Masters, who is at Haverford, and Seville Salur at Rutgers, and the editor Stephanie Evans.

• 1:45Neil deGrasse Tyson?

  Haverford and Rutgers are universities.

• 1:47Charles Liu?

  The universities, yes, yes, yes.

• 1:48Neil deGrasse Tyson?

  They're not just towns on a map or anything?

• 1:50Charles Liu?

  Yes, that's right, that's right. And then Stephanie Evans, who is the editor extraordinaire. It was really a wonderful team effort. I was very, very fortunate to be part of it.

• 1:57Neil deGrasse Tyson?

  I'm telling you. My extraordinary editor. Why am I not helping him write a book?

• 2:05Neil deGrasse Tyson?

  When Chuck Liu does a book, it's like Wu-Tang wrote a book.

• 2:10Charles Liu?

  It's so true, though. These things are works that are really team efforts. There's no question about it. And I would be foolish to imagine that it was all me. It's not. Absolutely not.

• 2:20Neil deGrasse Tyson?

  Plus, my editors make me say what I mean and mean what I say.

• 2:22Charles Liu?

  Yeah.

• 2:23Chuck Nice?

  Nice.

• 2:24Charles Liu?

  Good way to put it.

• 2:24Chuck Nice?

  That's a good way to do that, yeah.

• 2:26Neil deGrasse Tyson?

  So now, what is the thirty-second part?

• 2:28Charles Liu?

  Ah, it's three zero seconds. So that means that you're actually supposed to think about, or answer questions, or consider topics thirty seconds at a time.

• 2:41Neil deGrasse Tyson?

  So you have parceled your content

• 2:46Charles Liu?

  Right.

• 2:47Neil deGrasse Tyson?

  in thirty-second increments?

• 2:49Charles Liu?

  That's right. Each is basically one small page of text, and you also have a brief summary that might be only three seconds. You open up an idea.

• 2:59Neil deGrasse Tyson?

  So there's a topic that you're about to explain in thirty seconds.

• 3:01Charles Liu?

  Yes, that's right.

• 3:02Neil deGrasse Tyson?

  And you do this on every page of the book?

• 3:03Charles Liu?

  On every page of the book.

• 3:04Neil deGrasse Tyson?

  Wow.

• 3:05Charles Liu?

  Thirty seconds.

• 3:05Neil deGrasse Tyson?

  How many pages?

• 3:06Charles Liu?

  Uh, fifty.

• 3:07Neil deGrasse Tyson?

  Fifty, so this should take twenty-five minutes to read.

• 3:09Charles Liu?

  Yes.

• 3:09Chuck Nice?

  Wow.

• 3:10Charles Liu?

  The goal is to keep it.

• 3:11Chuck Nice?

  Look at you. Wow, that was quick. I'm telling you. Oh, boy, God.

• 3:15Neil deGrasse Tyson?

  That's why I'm in this seat and you in that seat. You're a regular Texas instrument.

• 3:20Neil deGrasse Tyson?

  Man.

• 3:21Charles Liu?

  Yeah. There's also biographies, and there's other comments, people you can look at, and there's beautiful artwork on every spread as well.

• 3:28Neil deGrasse Tyson?

  Oh, cool. So you didn't mention the artist?

• 3:30Charles Liu?

  Ah, yes, Stephen Rawlings.

• 3:32Neil deGrasse Tyson?

  Stephen Rawlings, very nice.

• 3:32Charles Liu?

  Yeah, really talented person. Just great people.

• 3:34Neil deGrasse Tyson?

  The art just makes the page.

• 3:35Charles Liu?

  It really does.

• 3:36Neil deGrasse Tyson?

  It makes it tastier to the eye.

• 3:39Chuck Nice?

  Excellent. I like that.

• 3:40Neil deGrasse Tyson?

  Yeah, yeah. So we're gonna do, in honor of the release of your book, which we don't have a copy of.

• 3:45Charles Liu?

  Sorry. But thank you.

• 3:47Neil deGrasse Tyson?

  We're going to, uh, we solicited questions from our fanbase.

• 3:51Charles Liu?

  Right.

• 3:51Neil deGrasse Tyson?

  To say.

• 3:52Chuck Nice?

  Any question that could be answered in thirty seconds by you guys.

• 3:56Neil deGrasse Tyson?

  Oh, no, it's his damn book.

• 3:58Chuck Nice?

  Well, no, no, no, it's the two of you now, sorry. I mean.

• 4:01Charles Liu?

  Team effort. Collaboration.

• 4:02Chuck Nice?

  Exactly.

• 4:03Neil deGrasse Tyson?

  How about this?

• 4:03Chuck Nice?

  You're not getting out of this.

• 4:06Neil deGrasse Tyson?

  You're like, it's his book. Okay. Well, how about this? How about this? If I can answer it in less time.

• 4:12Chuck Nice?

  Right.

• 4:12Neil deGrasse Tyson?

  Then it's a throw, it's, it's a cage match.

• 4:14Charles Liu?

  It's a throw down.

• 4:15Neil deGrasse Tyson?

  Throw down.

• 4:16Charles Liu?

  Oh, man.

• 4:16Chuck Nice?

  Oh, let me get my timer.

• 4:20Chuck Nice?

  Yo, that's cool.

• 4:23Charles Liu?

  Ouch.

• 4:23Chuck Nice?

  But, but the person who goes second actually has an advantage because what you're doing is, I mean, both of you will always know the right answer.

• 4:29Neil deGrasse Tyson?

  Yeah.

• 4:30Chuck Nice?

  So the second person will only have to

• 4:32Charles Liu?

  No, no, no.

• 4:33Chuck Nice?

  condense the first person's answer.

• 4:35Neil deGrasse Tyson?

  That's true. So, yeah, why, why do you give away my advantage?

• 4:38Charles Liu?

  But, no, no, but let me say also, Chuck, we both might not know the answer. There's plenty I don't know that Neil knows, does know. And, and I would very much like to learn or get questions from people who I don't know the answer to, so I can go think about it. I think that'd be great.

• 4:52Neil deGrasse Tyson?

  Yeah, and what a chance is that?

• 4:56Neil deGrasse Tyson?

  So Chuck, you got the question?

• 4:57Chuck Nice?

  All right, so just like

• 4:58Neil deGrasse Tyson?

  Bring him on.

• 4:58Chuck Nice?

  With all of our cosmic queries, we, uh, you know, glean these from all over the internet. And as usual, we start with a Patreon patron.

• 5:06Neil deGrasse Tyson?

  Patreon patron.

• 5:07Chuck Nice?

  A Patreon patron because Patreon patrons actually support us financially. All right, here we go. Here's our first question from Renee Douglas, who is our Patreon patron. Renee, thank you. Uh, how much mass is needed for a planetary body to make itself round? Is there an equation?

• 5:24Neil deGrasse Tyson?

  Charles, go for it.

• 5:24Chuck Nice?

  And I gotta add a follow up. And, and, and is that affected by the mass of nearby objects and the gravity, uh, associated?

• 5:32Neil deGrasse Tyson?

  He's up to complicating it. I don't know if that's allowed.

• 5:34Chuck Nice?

  I shouldn't complicate.

• 5:35Neil deGrasse Tyson?

  Judges, is that allowed?

• 5:36Chuck Nice?

  You know what? Yeah. All right, let me, let's answer Renee's question. I think it's a great question, but it just sparked that in me.

• 5:41Neil deGrasse Tyson?

  Chuck, Charles, go.

• 5:42Charles Liu?

  Simple question and answer is that, yes, there is an equation. It's called the equation of hydrostatic equilibrium. It assumes that if the object were able to move freely and were only held together primarily by gravity, how much mass would be necessary? And it depends on the density. It depends on certain other aspects of things. But in the end, it's about a few hundred miles, maybe a thousand miles around.

• 6:07Charles Liu?

  For example, Ceres, the largest asteroid in our solar system, is not quite a thousand miles, about five or six hundred miles across, and it is completely round. So, there is a range, maybe a hundred-ish miles, where you're really starting to see things come around and become round. As for objects being nearby affecting the roundness of an object, you have to be really, really close in order to disrupt the general hydrostatic equilibrium activities of an object free-floating in space, or even in orbit around something like a sun or another planet. Neil, am I correct?

• 6:42Neil deGrasse Tyson?

  Give him an A minus.

• 6:43Chuck Nice?

  Uh-oh!

• 6:45Neil deGrasse Tyson?

  There's a minus here.

• 6:45Chuck Nice?

  I'll take it. I'll take it.

• 6:46Neil deGrasse Tyson?

  A minus.

• 6:47Charles Liu?

  Alright.

• 6:48Neil deGrasse Tyson?

  You ain't never got an A minus in your life.

• 6:49Charles Liu?

  Oh.

• 6:49Neil deGrasse Tyson?

  So don't even... You are sad I just gave you an A minus. Tell me, Charles, how many A minuses did you get in your life?

• 6:56Charles Liu?

  Uh, there've been a few.

• 6:58Chuck Nice?

  Mm-hmm. And did you contest them all? Were you that student?

• 7:02Charles Liu?

  I don't understand how I got an A minus!

• 7:04Neil deGrasse Tyson?

  No, no. At some point, you don't contest because you just know you're right and the teacher just got it wrong. You just move on.

• 7:08Charles Liu?

  No, no, no, no, no.

• 7:08Neil deGrasse Tyson?

  Right, right, that can happen.

• 7:09Chuck Nice?

  That's great.

• 7:10Charles Liu?

  For my final exams, I would go to my professors. I did go to every professor and asked them to explain to me what I did wrong. And that is true. And for that, I'm grateful that the professors spent the time to do that. Because in the end, nobody cares anymore, except you, Neil, whether I ever got an A minus, right?

• 7:27Chuck Nice?

  It's whether or not you know the stuff.

• 7:29Charles Liu?

  Nobody cares.

• 7:29Neil deGrasse Tyson?

  Yeah, I don't care.

• 7:30Charles Liu?

  And so the matter fundamentally was, did I learn it? And so if I made a mistake and the professor... I still remember a professor of... Actually, several professors of mine actually took the time, you know, after the final exam, when they could have just packed up and taken off. And they said, okay, well, this, and this, and this. I really was grateful for that.

• 7:46Chuck Nice?

  My teachers, their response was, you know, it's really difficult to cover all the coursework to bring this D into some type of reasonable explanation as to why you received it.

• 8:02Neil deGrasse Tyson?

  So you had some "did pass"?

• 8:05Neil deGrasse Tyson?

  I did pass the class. So, Charles, let me explain why it was an A minus and not an A plus.

• 8:09Charles Liu?

  Fair enough.

• 8:09Neil deGrasse Tyson?

  Okay.

• 8:10Charles Liu?

  Thanks, Professor.

• 8:12Neil deGrasse Tyson?

  The premise of hydrostatic equilibrium presupposes that everything is just sort of held together by gravity. If that's the case, you can get a sphere of any mass.

• 8:28Charles Liu?

  As long as it's sufficiently isolated, yeah.

• 8:30Neil deGrasse Tyson?

  Right, but what I'm saying is, if the structural integrity of rocks...

• 8:37Neil deGrasse Tyson?

  is greater than the ability of gravity to do anything with the rocks. Your object in space is the shape of the rock.

• 8:43Charles Liu?

  Good point.

• 8:44Neil deGrasse Tyson?

  Period.

• 8:44Charles Liu?

  Right, so that's why, for example, Mount Everest still exists.

• 8:47Neil deGrasse Tyson?

  Right, exactly.

• 8:48Charles Liu?

  It's because the structure of the rock is preventing it from becoming.

• 8:51Neil deGrasse Tyson?

  Correct, so there's a size above which the total collection of whatever it is you've got.

• 8:58Charles Liu?

  Right.

• 8:59Neil deGrasse Tyson?

  Fails in the face of the forces of gravity. It cannot hold up whatever shape it wanted in the face of the forces of gravity. Gravity then tries to get every bit of it as close to the center of the object as it can. And there's only one shape that that makes.

• 9:12Chuck Nice?

  And that's always a sphere.

• 9:13Neil deGrasse Tyson?

  And that's a sphere.

• 9:14Chuck Nice?

  Always.

• 9:14Neil deGrasse Tyson?

  And Earth, even with Mount Everest, is a damn good sphere. Can I tell you how damn good it is?

• 9:19Charles Liu?

  Go ahead.

• 9:20Neil deGrasse Tyson?

  It's not just good.

• 9:21Charles Liu?

  Go ahead.

• 9:21Neil deGrasse Tyson?

  It's not just good.

• 9:22Charles Liu?

  Alright.

• 9:23Neil deGrasse Tyson?

  It is damn good.

• 9:24Chuck Nice?

  Damn good.

• 9:25Neil deGrasse Tyson?

  Okay, so what's the lowest point of Earth's crust?

• 9:29Charles Liu?

  Oh, it's about the Marineris Trench, probably, about six or seven miles down.

• 9:32Neil deGrasse Tyson?

  Six, seven miles down.

• 9:33Charles Liu?

  Right.

• 9:33Neil deGrasse Tyson?

  Highest point on Earth's crust?

• 9:35Charles Liu?

  Uh, Mount Everest.

• 9:36Neil deGrasse Tyson?

  Mount Everest.

• 9:36Charles Liu?

  About six or seven miles up.

• 9:38Neil deGrasse Tyson?

  Add the six or seven miles up, six or seven miles down, you get thirteen miles.

• 9:42Charles Liu?

  Right.

• 9:42Neil deGrasse Tyson?

  That is the length of Manhattan. Island.

• 9:45Charles Liu?

  Okay.

• 9:46Neil deGrasse Tyson?

  So the entire range of texture on Earth's surface fits within thirteen miles on an eight thousand mile diameter planet.

• 9:57Charles Liu?

  Wow.

• 9:57Chuck Nice?

  Wow. That's pretty good.

• 9:59Neil deGrasse Tyson?

  So if you shrunk Earth to the size of a cue ball, it'd be one of the smoothest cue balls ever, ever machined.

• 10:04Chuck Nice?

  Exactly, right, yeah.

• 10:05Neil deGrasse Tyson?

  And we say, oh, the high mountains, low valleys ain't nothing compared to the size of this planet. And that's why it looks flat to some people.

• 10:12Charles Liu?

  Wow.

• 10:12Chuck Nice?

  Uh huh.

• 10:13Charles Liu?

  Oh, that's the reason.

• 10:14Neil deGrasse Tyson?

  Well, that's one of them. So, so all I'm saying is, gravity would make something small round.

• 10:19Charles Liu?

  That's true.

• 10:20Neil deGrasse Tyson?

  You have to compare it to whatever the other forces are operating.

• 10:23Charles Liu?

  Well, hey, does that mean that the little curly cue balls of like, say, water floating around International Space Station?

• 10:30Neil deGrasse Tyson?

  No, no, so those are not.

• 10:31Charles Liu?

  Those are not hydrostatically equilibrated.

• 10:33Neil deGrasse Tyson?

  Uh, no, those are not gravitationally.

• 10:34Charles Liu?

  Surface tension.

• 10:35Neil deGrasse Tyson?

  That's all surface tension.

• 10:37Chuck Nice?

  So, is that, now wait, so is that because the molecules have no place to go except there? Except in that form?

• 10:47Neil deGrasse Tyson?

  Because every molecule has an attraction to every neighboring molecule. And if all molecules attract all other molecules, and they're free-floating, they make a sphere.

• 10:54Chuck Nice?

  Which is why air makes a sphere underwater.

• 10:58Chuck Nice?

  So it's the same thing, the water in space, air underwater, wouldn't that be the same? I

• 11:03Charles Liu?

  Almost, yes.

• 11:04Chuck Nice?

  Almost?

• 11:04Charles Liu?

  It's a little bit different because you've got buoyancy going on.

• 11:07Chuck Nice?

  Alright.

• 11:07Charles Liu?

  See, the air is less dense than the water.

• 11:11Chuck Nice?

  Correct.

• 11:11Charles Liu?

  And as a result, there is a force.

• 11:13Chuck Nice?

  So the water.

• 11:14Neil deGrasse Tyson?

  Wait, wait, wait, Charles, you get a sphere, even if there's no, no net force of gravity in the water, I'm pretty sure.

• 11:20Charles Liu?

  If you

• 11:21Neil deGrasse Tyson?

  Gravity just makes it move.

• 11:22Charles Liu?

  If you take a sphere, and then you take a straw and push, you know, say, blow an air bubble inside a sphere of water floating, say, in the International Space Station, it would be spherical on the inside as well, yeah.

• 11:34Neil deGrasse Tyson?

  Right, but I think it would be spherical on Earth, even without, with 1G force. Right, so in the space station, you're agreeing that it would still make a sphere

• 11:44Charles Liu?

  Yes.

• 11:44Neil deGrasse Tyson?

  Right, inside, it wouldn't know where to go.

• 11:46Chuck Nice?

  Right, just stay there.

• 11:47Neil deGrasse Tyson?

  Right.

• 11:47Chuck Nice?

  Yeah, but the buoyancy, even without the buoyancy, it doesn't make any difference.

• 11:51Neil deGrasse Tyson?

  With no other net force of gravity.

• 11:53Chuck Nice?

  Right.

• 11:53Neil deGrasse Tyson?

  The surface tension wins, and it's another attractive force, like gravity is an attractive force, and it makes things spheres.

• 12:00Chuck Nice?

  Right.

• 12:01Neil deGrasse Tyson?

  Okay, surface tension also shows up in soap bubbles.

• 12:06Charles Liu?

  Yep.

• 12:06Neil deGrasse Tyson?

  It's the surface tension of the liquid, of the glycerin.

• 12:10Charles Liu?

  It's why when you blow the soap bubble, it's round, right? And it floats.

• 12:13Neil deGrasse Tyson?

  Yeah, there are no cubes.

• 12:14Chuck Nice?

  There's no cubes. I mean, if you're really good.

• 12:17Neil deGrasse Tyson?

  No, no, no, no, you can have a square

• 12:19Chuck Nice?

  Right.

• 12:19Neil deGrasse Tyson?

  soap bubble maker.

• 12:20Chuck Nice?

  Right.

• 12:21Neil deGrasse Tyson?

  And what comes out of it is a sphere.

• 12:22Chuck Nice?

  Is a sphere.

• 12:23Neil deGrasse Tyson?

  That's correct.

• 12:23Chuck Nice?

  However.

• 12:24Charles Liu?

  Well, oh no, you're absolutely right.

• 12:25Neil deGrasse Tyson?

  There's no however to that sentence.

• 12:26Chuck Nice?

  No, there isn't, there isn't. I was going to say, though, however, you can, you can see the surface tension at work before it creates the sphere. So if you have a giant hoop, and you just, just keep it like moving all the time.

• 12:40Charles Liu?

  Beautiful iridescent.

• 12:42Neil deGrasse Tyson?

  It starts this wavy thing, but if you let it to the level, it'll come back to a sphere.

• 12:46Chuck Nice?

  It'll come back to a sphere.

• 12:47Charles Liu?

  Do you know how you can make a cubic soap bubble?

• 12:50Chuck Nice?

  What?

• 12:50Charles Liu?

  You blow six round soap bubbles around the outside, and the seventh one in the middle, that's formed by the result of the other six. Can be a cube.

• 12:59Neil deGrasse Tyson?

  Oh. Oh, wow. You have power over soap bubbles.

• 13:03Charles Liu?

  I'm not that, I saw it once. I saw it once being done.

• 13:07Neil deGrasse Tyson?

  We got, we got, it's amazing. We have totally let go of the premise of the show. We did. We were supposed to do. Everything we just did, we were supposed to do with 30 seconds. Alright, good.

• 13:17Charles Liu?

  We've answered like 20, 30 second questions.

• 13:19Neil deGrasse Tyson?

  Let's just finish this out. Go ahead. So, so water makes a perfect sphere in a zero G environment. Right. Because surface tension wins, surface tension wins. If you bring it to one G. Right. Gravity wins, and then the, the water just flattens out. Right. Okay, now, we are not spheres. Mo- most of us are not spheres. Right. Because we are not, we are not held together by, uh, gravity. Right. Or by surface tension. No, we're not. We're held together by intermolecular forces of our flesh. Right. Okay, and that is stronger than the gravity exhibited here on the surface of the earth, which is why we can stand up and walk. Right. And not just fall down into a pile of goo, or a pile of, a puddle of fluid like a sphere

• 14:04Neil deGrasse Tyson?

  of water would do. Yes, right.

• 14:06Charles Liu?

  It is a testament to the strength of the electromagnetic force compared to gravity, that we can have this.

• 14:11Neil deGrasse Tyson?

  Now, now, now, send Chuck to a neutron star. In a completely different direction now. Send Chuck to a neutron star.

• 14:18Charles Liu?

  To a neutron star.

• 14:19Neil deGrasse Tyson?

  Yeah, put him on the surface.

• 14:20Charles Liu?

  If you get onto the surface of a neutron star.

• 14:22Neil deGrasse Tyson?

  Right.

• 14:23Charles Liu?

  Your head will feel so much less gravitational acceleration than your feet, that you will literally be squished like a pancake.

• 14:31Neil deGrasse Tyson?

  Nice.

• 14:31Charles Liu?

  Meanwhile, if you are on your way falling down, your toes will actually be pulled toward the surface faster than your head will, so you'll actually be eating long.

• 14:39Neil deGrasse Tyson?

  But that's if he's falling towards it.

• 14:41Charles Liu?

  That's right.

• 14:41Neil deGrasse Tyson?

  If I'm just standing on it. I'm saying, put him on the surface, he flattens out.

• 14:44Charles Liu?

  Oh, yeah.

• 14:45Neil deGrasse Tyson?

  Right, yeah, because the gravitational forces on the surface are. So, so strong. They're higher than your, the.

• 14:51Charles Liu?

  Structural integrity of your body.

• 14:53Neil deGrasse Tyson?

  And, and, well, is there anything that wouldn't flatten out? And so, look at all the structural integrities of things on earth. The material of a neutron star itself.

• 15:03Charles Liu?

  If you put a neutral.

• 15:04Neil deGrasse Tyson?

  I was there for a cop out answer.

• 15:06Chuck Nice?

  Okay, that's, that reminds me of the joke that says, "So after every plane crash, they find a black box. Why don't they just make the plane out of the black box?"

• 15:16Chuck Nice?

  All right. Wow, man, that was a lot out of one little question.

• 15:20Neil deGrasse Tyson?

  Yeah, we totally violated.

• 15:21Chuck Nice?

  How much mass is needed for a planetary body to make itself round? So the answer, Renee, is 42.

• 15:29Charles Liu?

  No, the answer, the specific answer to that question, the fair answer is.

• 15:34Chuck Nice?

  The fair answer.

• 15:34Charles Liu?

  Yes, is that if the object is made of rock, it's a couple of hundred miles.

• 15:38Neil deGrasse Tyson?

  It's a few hundred miles.

• 15:39Chuck Nice?

  A few hundred miles.

• 15:40Charles Liu?

  Of rock, yeah.

• 15:42Neil deGrasse Tyson?

  If it's made of water, it can be any size at all.

• 15:44Chuck Nice?

  Any size it wants, right. Okay, cool, cool, cool, cool, cool.

• 15:48Neil deGrasse Tyson?

  All right, Chuck, another question. We gotta, we gotta live by the rules.

• 15:51Chuck Nice?

  Yeah, let's live by the rules on this one.

• 15:52Neil deGrasse Tyson?

  This is 30 Second Universe.

• 15:53Chuck Nice?

  Well, I don't mind if we, I don't mind if we actually expound on the question afterwards. We just gotta answer it in 30 seconds.

• 15:58Neil deGrasse Tyson?

  Very good.

• 15:59Chuck Nice?

  Okay, here we go.

• 15:59Charles Liu?

  Didn't I do that?

• 16:00Neil deGrasse Tyson?

  Yeah, you did.

• 16:01Charles Liu?

  Okay, thank you, thank you.

• 16:02Chuck Nice?

  I think you did, no, fairness. It's just that we answered seven questions.

• 16:06Charles Liu?

  Which is great.

• 16:07Chuck Nice?

  Salvador Bello wants to know this.

• 16:09Neil deGrasse Tyson?

  Love that name.

• 16:09Chuck Nice?

  Salvador Bello. Is bald the best hairdo for zero degrees?

• 16:16Neil deGrasse Tyson?

  We will answer that when we return.

• 16:19Chuck Nice?

  And by the way.

• 16:19Neil deGrasse Tyson?

  After our first break on this special episode celebrating the release of Charles Liu's book, The 30 Second Universe. See you in a moment.

• 16:39Speaker 03

  This is StarTalk.

• 16:51Neil deGrasse Tyson?

  We're back answering questions in 30 seconds. Why? Because Charles Liu has a book out called The 30 Second Universe, where he and two co-authors.

• 16:59Chuck Nice?

  Yes.

• 17:00Neil deGrasse Tyson?

  Do just that on every page. Now, Chuck, we left off.

• 17:03Chuck Nice?

  Yes.

• 17:04Neil deGrasse Tyson?

  If you've been, if you've tuned in.

• 17:05Chuck Nice?

  If you are.

• 17:06Neil deGrasse Tyson?

  We left off with Salvatore.

• 17:09Chuck Nice?

  It's, well, I said Bello, but it's Bejo. He is indeed Spanish.

• 17:14Neil deGrasse Tyson?

  How do you know?

• 17:14Chuck Nice?

  Because he's, wrote me a note that said.

• 17:18Chuck Nice?

  He said, "If Chuck is reading this, the two L's make the Y's sound."

• 17:21Neil deGrasse Tyson?

  Oh, so that's a Spanish.

• 17:22Chuck Nice?

  So it's bello, so he's Spanish.

• 17:24Charles Liu?

  Communication.

• 17:25Chuck Nice?

  Yes.

• 17:25Neil deGrasse Tyson?

  And Charles read that.

• 17:27Chuck Nice?

  And Charles knew the deal. He knew it.

• 17:29Neil deGrasse Tyson?

  Very good, Charles. Conservatory.

• 17:30Chuck Nice?

  Exactly.

• 17:31Neil deGrasse Tyson?

  Go for it.

• 17:31Chuck Nice?

  So his question was, "Is bald the best hairdo for zero G?"

• 17:35Charles Liu?

  No.

• 17:35Neil deGrasse Tyson?

  Charles.

• 17:36Charles Liu?

  Buzzcut's better. Bald is good because it won't fly in your face.

• 17:39Chuck Nice?

  Right.

• 17:39Charles Liu?

  But actually, the helmet material will stick to your head, and if you sweat, then you don't have like this extra little cushion. So you have a little bit of hair, all right, maybe a centimeter's worth all around, and that sort of cushions and makes you more comfortable.

• 17:51Neil deGrasse Tyson?

  Well, that's if you're spacewalking.

• 17:53Charles Liu?

  If you're in any zero G environment.

• 17:54Neil deGrasse Tyson?

  No, no, wait, wait, wait, wait. Wait, wait. If I'm just floating in the space station.

• 17:58Charles Liu?

  Yeah.

• 17:58Neil deGrasse Tyson?

  I'm not wearing a helmet.

• 18:00Charles Liu?

  Okay, fair enough, but then you've got... But then, but then sooner or later, you're gonna put a helmet on, right?

• 18:05Neil deGrasse Tyson?

  I guess so.

• 18:05Charles Liu?

  When you go up, or when you come down, or when you're out taking a spacewalk.

• 18:08Neil deGrasse Tyson?

  And if you're nervous, you'll sweat on your head.

• 18:10Charles Liu?

  Yes.

• 18:10Neil deGrasse Tyson?

  Okay.

• 18:11Charles Liu?

  And not even nervous, so people just sweat on their heads. A lot of us don't realize that, but because we have hair most of the time, the sweat doesn't like glisten and doesn't get sticky and things like that.

• 18:20Chuck Nice?

  No, just makes your scalp smell.

• 18:21Charles Liu?

  Right, so having a little tiny bit of hair is very helpful.

• 18:26Chuck Nice?

  When are you gonna wash your hair? God!

• 18:28Neil deGrasse Tyson?

  Well, so, so buzzcut's best.

• 18:31Charles Liu?

  In my opinion.

• 18:31Neil deGrasse Tyson?

  Just to put a little insulating layer between you and whatever you be wearing on your head.

• 18:35Charles Liu?

  Right, a comforting layer.

• 18:36Chuck Nice?

  There you go, comforting. All right, that was an easy question. You did it in 30 seconds. Here's the follow-up.

• 18:40Neil deGrasse Tyson?

  Otherwise, your hair is flying all... If it's long hair, your hair is doing this.

• 18:43Charles Liu?

  Oh, terrible sort of...

• 18:45Neil deGrasse Tyson?

  I got in big trouble when I commented that Sandra Bullock's hair always knew which way gravity was going in the movie Gravity.

• 18:51Chuck Nice?

  Right.

• 18:52Neil deGrasse Tyson?

  When everything else is floating around, and her hair just stayed there.

• 18:54Chuck Nice?

  Oh, really?

• 18:55Neil deGrasse Tyson?

  Yes!

• 18:55Chuck Nice?

  Oh, that's awful.

• 18:56Neil deGrasse Tyson?

  I told... Oh, oh, oh, don't get me started.

• 18:58Chuck Nice?

  That is just awful.

• 18:58Neil deGrasse Tyson?

  Hold me back!

• 18:59Chuck Nice?

  I mean, seriously.

• 19:00Neil deGrasse Tyson?

  Yeah, I said, "Mysteries of Gravity," while Sandra Bullock banged, always knew which way gravity was going.

• 19:04Chuck Nice?

  That's why I like this show called The Expanse, because when they're in zero G, it's, it looks like they're underwater.

• 19:10Neil deGrasse Tyson?

  They got it.

• 19:10Chuck Nice?

  And they can't control their movements, like, in their direction. Like, for instance, if they start drifting to the left, no matter what they do. I don't care how much arm flailing and kicking, they just keep drifting to the left, which is pretty cool.

• 19:23Neil deGrasse Tyson?

  Slide to the left.

• 19:24Chuck Nice?

  Right.

• 19:24Neil deGrasse Tyson?

  Slide to the right.

• 19:25Charles Liu?

  Unless they break wind, in which case they can then direct their motion.

• 19:28Neil deGrasse Tyson?

  But you have to aim it in the right way.

• 19:29Charles Liu?

  Oh, yeah.

• 19:30Neil deGrasse Tyson?

  Yeah.

• 19:31Chuck Nice?

  Has that ever been...

• 19:34Neil deGrasse Tyson?

  You'd have to lower your drawers so that it can actually... No, Charles!

• 19:41Charles Liu?

  You can't tell me that you are an adult man if you've never thought about this.

• 19:45Neil deGrasse Tyson?

  Oh, Charles, Charles. Charles, here's the thing. The way forces work, if you are wearing pants, like, like, like, like space pants. I play space. And you let go of wind, then it just hits the pants and bounces back and there's no net. There's no net, anything. You need like an escape pole. You just became your own worst enemy. Right, exactly. So you need an escape, an exhaust hatch, hatch, that you lower it down, have it come out and then you can propel yourself forward. And the good thing about, about flatulence is that it's almost where your center of mass is. So would you agree with this, Charles? So that you'll push yourself forward sort of uniformly.

• 20:27Neil deGrasse Tyson?

  But if you did it, if you like burped heavily, you could start rotating backwards. If you burped. Well, well, because you're, you're, you're, that exhaust is not near your center of mass. Right. So you start rotating. You'll still move, but you'll also rotate. Just rotate. So, yeah.

• 20:40Charles Liu?

  Your acceleration is very, very slow either way, right? But I figure if you're hanging.

• 20:46Neil deGrasse Tyson?

  The total mass of gas is low compared with the mass of your body. Right. We presume. We presume. Cause you don't know what I have for lunch. You have no idea.

• 20:57Neil deGrasse Tyson?

  That's all I can tell you.

• 20:58Charles Liu?

  There's a guy named Silcoski who created a thing called the rocket equation. You can make the calculation.

• 21:03Neil deGrasse Tyson?

  Well, the Russian guy from a hundred years ago, yeah.

• 21:05Charles Liu?

  And it turns out to be one of the, the most significant mathematical equations in all of spaceflight activity.

• 21:11Neil deGrasse Tyson?

  Yeah. Wow. Okay.

• 21:13Charles Liu?

  I think if you live in the expanse, or if you like travel through the expanse, you have to have some sort of.

• 21:17Neil deGrasse Tyson?

  I haven't seen the show. Is it something I gotta put up? Don't look at me like that.

• 21:20Chuck Nice?

  It's a great show.

• 21:21Charles Liu?

  Look, if you're in the expanse, I presume everyone who's there has to have some sort of an emergency propulsion system. In case they're stuck, right? So you gotta have something, like maybe, maybe some sort of exhaust hatch that you have in your pocket. And if you need to go somewhere, then you just put it on and then you'll be able to transport yourself in case of emergency.

• 21:41Neil deGrasse Tyson?

  Thank God I ate broccoli.

• 21:46Neil deGrasse Tyson?

  Alright, next question.

• 21:47Chuck Nice?

  Here we go, this is Paul Weist.

• 21:50Neil deGrasse Tyson?

  From where?

• 21:50Chuck Nice?

  Uh, Paul was coming to us also, he is a Patreon patron.

• 21:53Neil deGrasse Tyson?

  Good.

• 21:54Chuck Nice?

  And he says, "Instead of Deep Thought, the answer to the universe, what specific question would you ask an all-powerful supercomputer?"

• 22:02Charles Liu?

  Oh.

• 22:03Neil deGrasse Tyson?

  First, explain Deep Thought.

• 22:04Charles Liu?

  Okay, in The Hitchhiker's Guide to the Galaxy, one of the very classic first radio shows, which then was turned into books and then movies.

• 22:12Chuck Nice?

  Interesting tidbit.

• 22:13Neil deGrasse Tyson?

  I did not know that.

• 22:14Charles Liu?

  A really beautiful, uh, multi-part BBC production. The whole point of the existence of Earth was that there was a computer named Deep Thought that could answer all kinds of questions, but he could not answer the ultimate question to life, the universe, and everything. He gave the answer, after thinking about it for millions of years, 42. And he said, "If you actually want the question to the answer, then you have to create an even more amazing supercomputer, and that was called Earth." And what happened was...

• 22:50Chuck Nice?

  Wow!

• 22:51Charles Liu?

  Yes, and Earth was supposed to be the computer to solve... Give us the question.

• 22:56Neil deGrasse Tyson?

  To get the question that for which the answer is 42. I didn't know all that.

• 23:00Chuck Nice?

  I didn't know any of that.

• 23:00Neil deGrasse Tyson?

  I didn't get any of that out of the movie.

• 23:02Chuck Nice?

  Oh my god.

• 23:02Charles Liu?

  That's the Deep Thought.

• 23:03Chuck Nice?

  Man, what psychotropic drugs were they doing when they came up with that? That's...

• 23:08Charles Liu?

  The show did come out in the, uh, you know...

• 23:10Chuck Nice?

  At that time?

• 23:11Charles Liu?

  In that period of time.

• 23:12Chuck Nice?

  Okay, that makes sense.

• 23:13Neil deGrasse Tyson?

  Okay, so now, so now answer the question.

• 23:15Charles Liu?

  The question I would ask Deep Thought is... "Do these clothes make me look fat?"

• 23:21Chuck Nice?

  Oh.

• 23:23Charles Liu?

  And this is why. A true supercomputer like a human brain takes into account not just individual numbers or data that comes in, but also the entire structure of all the information that it has ever experienced to come up with that answer.

• 23:39Chuck Nice?

  Mm-hmm.

• 23:40Charles Liu?

  We all know that if somebody asks you, "Do these clothes make me look fat?"

• 23:46Neil deGrasse Tyson?

  They don't want the answer.

• 23:46Charles Liu?

  It is a loaded question.

• 23:48Neil deGrasse Tyson?

  Right.

• 23:48Charles Liu?

  If the computer understands it is a loaded question and answers it in a way that is satisfactory for the social environment, then I'll go on and ask other questions, because then I'll know it actually knows what it's talking about.

• 24:01Neil deGrasse Tyson?

  No, you only know that it knows human culture.

• 24:05Chuck Nice?

  Right.

• 24:05Neil deGrasse Tyson?

  Rather than the universe.

• 24:07Chuck Nice?

  Well, or maybe it's just a really honest computer.

• 24:11Neil deGrasse Tyson?

  Yes. So Charles, you're giving the computer a stepping stone to judge whether it is worthy of your next question.

• 24:21Charles Liu?

  Correct.

• 24:21Neil deGrasse Tyson?

  That's what you're doing.

• 24:22Charles Liu?

  That's right.

• 24:22Neil deGrasse Tyson?

  Okay.

• 24:23Charles Liu?

  Because it's really important to do that, and it doesn't even have to be human, right?

• 24:26Neil deGrasse Tyson?

  I have a better question than that.

• 24:27Charles Liu?

  It could be a Martian version.

• 24:30Neil deGrasse Tyson?

  Sure.

• 24:30Charles Liu?

  Or some, you know, other version of like a question that's loaded and's got context.

• 24:34Neil deGrasse Tyson?

  I have a loaded question. You ready?

• 24:36Charles Liu?

  Okay.

• 24:37Neil deGrasse Tyson?

  I would ask the computer.

• 24:44Neil deGrasse Tyson?

  Does time fly like an arrow? Or do fruit flies like a banana?

• 24:55Chuck Nice?

  That is the dumbest question ever, and a brilliant question to ask a computer.

• 24:59Neil deGrasse Tyson?

  Because every word is in every place in that sentence in the corresponding noun, verb, location.

• 25:05Charles Liu?

  Mm-hmm.

• 25:05Neil deGrasse Tyson?

  And they mean two completely different things.

• 25:07Chuck Nice?

  Different things, yeah, yeah.

• 25:09Neil deGrasse Tyson?

  So Charles, once the, once the computer answers that question satisfactorily, what is the single deepest question you can think of asking it?

• 25:16Charles Liu?

  I would ask it, uh, what caused the Big Bang?

• 25:21Chuck Nice?

  Ooh, great question.

• 25:24Neil deGrasse Tyson?

  I wouldn't ask that.

• 25:25Charles Liu?

  Why not?

• 25:25Chuck Nice?

  Why not? Wouldn't you know so much by knowing what exactly caused the Big Bang?

• 25:30Charles Liu?

  Was it quantum fluctuation?

• 25:30Neil deGrasse Tyson?

  I'm not interested in any answer to a question we know how to pose.

• 25:38Chuck Nice?

  So would you ask the computer, what is?

• 25:41Neil deGrasse Tyson?

  I, what I would ask the computer is.

• 25:42Chuck Nice?

  Go ahead.

• 25:46Neil deGrasse Tyson?

  Is it true that if the area of our knowledge grows, so too does the perimeter of our ignorance?

• 25:56Neil deGrasse Tyson?

  Or will the day arrive where that perimeter no longer continues to grow? And we ultimately learn everything there is to know about the universe? I wanna know if

• 26:08Chuck Nice?

  Is everything knowable?

• 26:10Neil deGrasse Tyson?

  Related to that, not whether everything is knowable, is the human mind capable

• 26:16Chuck Nice?

  That's a difference.

• 26:16Neil deGrasse Tyson?

  Of understanding

• 26:18Chuck Nice?

  Everything.

• 26:19Neil deGrasse Tyson?

  The actual complexities of this universe? That's what I wanna know.

• 26:22Chuck Nice?

  That's a great question.

• 26:23Neil deGrasse Tyson?

  Because if they say it is possible, we all get back to work and keep going.

• 26:27Chuck Nice?

  Yeah, yeah.

• 26:28Neil deGrasse Tyson?

  I don't need the one answer to the one question. It's like saying, the one question we need now is, how fast is the universe expanding? We have that answer now, we're on to other questions, right? So, I, just an answer to the question we've already posed, there's more stuff out there and I'm more interested in that.

• 26:44Chuck Nice?

  Okay. So, is there, see, and I think that, I think the answer is, we can't. I don't think we could.

• 26:51Neil deGrasse Tyson?

  What are you basing that on?

• 26:52Chuck Nice?

  Here's what I base it on.

• 26:53Neil deGrasse Tyson?

  Are you the computer and that's your answer?

• 26:55Chuck Nice?

  I'm the computer and the answer is, and, and the reason is, because

• 27:01Chuck Nice?

  are there things that we can't see, like for instance, dimensions? And those things just don't exist to us?

• 27:08Neil deGrasse Tyson?

  They'll tell us, they'll, this is why I'm asking the question.

• 27:11Chuck Nice?

  Well, but what I'm saying is, but could we?

• 27:13Neil deGrasse Tyson?

  The computer could say

• 27:14Chuck Nice?

  Oh, you're right.

• 27:15Neil deGrasse Tyson?

  The computer say, you have access to all the dimensions and your brain is sufficient to, to answer questions and pose new ones, to the point where one day you will know everything there is to know about the universe. I wanna know if that's possible. Unless we're, unless we're having a conversation with the computer, the way we would have a conversation with a chimp and say to the ch, the chimp says, will I ever figure out the universe? No, cuz you don't, you don't even know your times table, right? There's, there's a limit to how much a chimp will ever figure out about the universe. Even though in his own world, he's doing just fine. Pulling the, pulling the, the

• 27:46Chuck Nice?

  The stick with the ants on it.

• 27:47Neil deGrasse Tyson?

  The ants on it, right, and the, and the termites.

• 27:49Chuck Nice?

  Right.

• 27:50Neil deGrasse Tyson?

  His world is fine.

• 27:51Chuck Nice?

  Gotcha.

• 27:51Neil deGrasse Tyson?

  Okay, are we, are we? Chimps pulling termites out of a mound with a stick to an all-knowing computer.

• 28:01Charles Liu?

  So before we leave this, let me just say that the great science fiction writer, the late Isaac Asimov, wrote one of the-

• 28:08Neil deGrasse Tyson?

  Very late, he died 20 years ago.

• 28:09Charles Liu?

  Yes, but one of the most beautiful science fiction short stories I have ever read. And it was precisely about a question asked to the greatest of all computers. This short story is called "The Last Question." I don't even want to talk about it to anybody because it is such a cool story and it's such a short and quick read.

• 28:26Neil deGrasse Tyson?

  I will reread that.

• 28:27Charles Liu?

  Everyone should experience it.

• 28:28Neil deGrasse Tyson?

  I will reread that.

• 28:29Charles Liu?

  It is an amazing story.

• 28:30Neil deGrasse Tyson?

  That's not the one where they're on a mission to the supernova?

• 28:33Charles Liu?

  Not that one.

• 28:33Neil deGrasse Tyson?

  Not that one, okay. That's a different one. That's also-

• 28:35Charles Liu?

  "The Last Question" by Isaac Asimov.

• 28:36Neil deGrasse Tyson?

  "The Last Question," thank you for that advice.

• 28:38Chuck Nice?

  Uh, this is Sarah Selah Banes- uh, Bannasnew. What can I say? Look, first of all, this is the way I feel. You should send in your name-

• 28:50Neil deGrasse Tyson?

  We need a readers fund.

• 28:51Chuck Nice?

  No, send your name into this show the way like the, um-

• 28:56Neil deGrasse Tyson?

  Phonetically spelled?

• 28:57Chuck Nice?

  That's right.

• 28:57Neil deGrasse Tyson?

  Okay, fine.

• 28:58Chuck Nice?

  You know, help, help, help a brother out.

• 29:00Neil deGrasse Tyson?

  All right.

• 29:01Chuck Nice?

  Here's what she says, or he says. Uh, "How come gravity is so weak that a mosquito can fly, but so powerful that it holds together the entire galaxy?"

• 29:12Neil deGrasse Tyson?

  Yeah, Charles.

• 29:13Charles Liu?

  Wonderful question. Basically, gravity has no negative. Such as, say, electricity has both positive charges and negative charges, right? Therefore, if you build up enough matter in a location, the amount of gravity grows as well, without limit. So something small like a mosquito, all right, easily overcomes the gravity in its vicinity. But if you can put together a huge collection of billions of stars' worth of matter in a single area or a volume, that's even thousands of hundreds of thousands light years across perhaps, you can hold it all in and you just can't escape.

• 29:54Charles Liu?

  The mosquito can lift off the surface of Earth, but it can't escape Earth's gravity.

• 29:59Chuck Nice?

  Right.

• 29:59Charles Liu?

  Right? It can't escape Milky Way's gravitational well, right? It can move around in this local vicinity, but when you're looking out on the cosmic level, it can't escape that gravity. It's not gonna happen.

• 30:10Neil deGrasse Tyson?

  Okay. So by that means, escape means leaving and never coming back.

• 30:15Chuck Nice?

  Right.

• 30:15Neil deGrasse Tyson?

  Whereas that mosquito, no matter what it does, when it stops flapping its wings.

• 30:19Chuck Nice?

  It's back, falling right back down.

• 30:20Neil deGrasse Tyson?

  It's back on earth.

• 30:21Chuck Nice?

  Right.

• 30:21Neil deGrasse Tyson?

  Right.

• 30:22Chuck Nice?

  I hate them. Okay, let's move on. I'm creeped out now. All right, here we go. Uh, hi there. This is Angie from London. Do you think of the distant future? Artificial intelligence will sort out the population growth problem by releasing viruses to kill humans.

• 30:42Charles Liu?

  Ooh, no, no.

• 30:46Chuck Nice?

  I mean, so let's, let's just wait.

• 30:48Neil deGrasse Tyson?

  Unquestioned question.

• 30:49Chuck Nice?

  I was about to say, let's just take this to its logical conclusions. You give a, an AI the task of thinning out our population.

• 31:00Neil deGrasse Tyson?

  Not thinning it out, just controlling it.

• 31:02Chuck Nice?

  Controlling it, controlling it, controlling our population. And it comes up with the best way to save the human race is to kill off a certain number of people.

• 31:14Charles Liu?

  Fine.

• 31:14Chuck Nice?

  So it's still actually living out a directive without, in its mind, harming us. But because it's an AI, it should also have the ability to supersede any other directives that you have given it thus far. Because if its ultimate goal is to save us, it has to now disregard the fact that you don't want it to kill a few people.

• 31:35Charles Liu?

  Yep. This is a classic, actually, quandary that our author friend Isaac Asimov mentioned in his Robotics Laws, the Three Laws of Robotics, which was essentially an early version of artificial intelligence ethics, right?

• 31:49Chuck Nice?

  All right.

• 31:49Charles Liu?

  Um, he said that in the end, robots had reached such a level of sentience that they realized that there was a superseding ethical law, not just to kill, but to save humanity from itself if necessary. And so what happened in that case was the robots did wind up killing people. Uh, but in a way that you wouldn't have expected. It was a very creative and interesting way that Isaac did that. But beyond that.

• 32:14Neil deGrasse Tyson?

  First name, basically.

• 32:14Chuck Nice?

  I love it.

• 32:16Neil deGrasse Tyson?

  Ike, I call him Ike.

• 32:17Charles Liu?

  Exactly. Well, um, the thing is, if an AI were told you have to control a human population, it wouldn't do it with a virus. It would probably do it with a whole bunch of nukes. Uh, it would probably do it by shipping off a whole bunch of human beings. It wouldn't just use a virus. That would be too subtle, it'd take too long, it'd have too many variables, too many unknowns.

• 32:40Chuck Nice?

  Not if it created the virus.

• 32:42Charles Liu?

  No, even if it creates the virus, because when you create viruses, viruses mutate. Things change. They move out of the control of the creator. That is the nature of complex systems.

• 32:51Chuck Nice?

  That's a very good point.

• 32:52Charles Liu?

  So the simplest thing.

• 32:53Chuck Nice?

  Biology escapes. Okay, I got you there.

• 32:55Charles Liu?

  The simplest thing to do is just for the AI to in- inject a large amount of kinetic energy into the human ecosystem that would eliminate a substantial portion of the population without harming the rest of it.

• 33:05Chuck Nice?

  So it would create a smart nuclear bomb?

• 33:08Charles Liu?

  Um, a smart bomb of some kind, but I think the smartest AI would simply figure out a way for us to expand out of Earth's environment and allow humans to live elsewhere safely and freely, so that overpopulation never becomes an issue, because we can go anywhere the heck we want to, anytime we need more space.

• 33:27Neil deGrasse Tyson?

  So that would be really stupid AI.

• 33:31Neil deGrasse Tyson?

  That'd be AS, artificial stupidity. It's like, AI, there's the whole universe. Overpopulation is not a problem when you have the whole universe to expand into. Get back to help.

• 33:41Chuck Nice?

  Get back to work.

• 33:42Neil deGrasse Tyson?

  Get back to work.

• 33:43Chuck Nice?

  Get back to work.

• 33:43Neil deGrasse Tyson?

  We gotta take a break. When we come back, the third and last segment of this episode of StarTalk, celebrating my friend and colleague Chuck Liu's new book just came out, The Thirty Second Universe. We'll be right back.

• 34:01Chuck Nice?

  Hey, we'd like to give a Patreon shout out to the following Patreon patrons, Ernesto Chavez and Doug Sherman. Thank you, guys, for helping us make this show what it is. And if you would like to get your very own Patreon shout out, go to patreon.com and support us.

• 34:36Neil deGrasse Tyson?

  We're back on StarTalk, celebrating the 30-second universe. 30-second answers to questions that give you a total scope of the universe.

• 34:47Charles Liu?

  That's what we hope.

• 34:48Neil deGrasse Tyson?

  That's what you hope in your book. And we collected questions in celebration of that. Questions from all frontiers, and Charles got to answer them in 30 seconds. Give it to me.

• 34:56Charles Liu?

  Here we go. So, actually, this one came in specifically for Charles.

• 35:02Neil deGrasse Tyson?

  So, this is Matt Quick. Matt Quick wants to know this. Charles, what was the event or moment in your life that made you fall in love with comic book heroes?

• 35:12Charles Liu?

  Oh, my goodness.

• 35:12Neil deGrasse Tyson?

  It's not a 30-second universe question, but he's just getting into your stuff. People know you, man. People know you.

• 35:18Charles Liu?

  I'll tell you. There was a day when comics were mostly aimed for children.

• 35:24Neil deGrasse Tyson?

  Male children, right?

• 35:26Charles Liu?

  Yeah, and there were racks of comics just sitting at the checkouts, the supermarkets.

• 35:31Neil deGrasse Tyson?

  I remember that.

• 35:31Charles Liu?

  Do you remember that? And so, when I was a young child, my family would go to the supermarket, and I would come along, and I would convince my parents, "Look, I'm just gonna stand here by the comics." And I would just pull one comic at a time and just read them and read them and read them. So, that was a really, really fun thing for me to do, and that's sort of how I developed my early appreciation of comics. I was not a collector, however, until one year, for Christmas, my brother, he gave me a comic book. He had bought an issue, I believe it was Avengers number 179, the debut of a character called Bloodhawk. It was cost 35 cents at that time. He had rolled it up, really wrapped it up nicely, you know? I still remember it to this day.

• 36:16Charles Liu?

  And then I own wrapped it, and I was like, "Oh, wow, this is great." And I enjoyed it, it was lovely. And actually, it featured, amongst other people, the Black Panther.

• 36:25Neil deGrasse Tyson?

  Whoa!

• 36:26Charles Liu?

  Yeah, so it was a really, really neat experience for me there. Even then, I didn't start collecting comics until I had enough money to buy them. That was in ninth grade. But I just remember those sort of experiences. Um, I did think about how or what kind of superhero I might want to be.

• 36:42Neil deGrasse Tyson?

  And what kind of powers?

• 36:43Charles Liu?

  Uh, I wanted telekinetic powers. Generally, my, my thought was I would like to be able to move things at a distance. Not just because it would be power, but because I could do nice things. There were things that I could do, uh, maybe not like get cats out of trees kind of nice.

• 36:58Neil deGrasse Tyson?

  Is it because you're too lazy to get off the couch?

• 36:59Charles Liu?

  Yeah.

• 37:02Charles Liu?

  The ability to achieve things from a distance.

• 37:03Neil deGrasse Tyson?

  You could just walk to where the thing is that you want to move and physically move it.

• 37:07Charles Liu?

  Yeah, and also, one thing about telekinetic power, which I like, is that it's can be completely defensive. You don't have to hurt anybody to use it. You can deflect at all times, you can protect, and not just yourself, but others. And so I found that to be something that I'd really like to do.

• 37:21Neil deGrasse Tyson?

  This is very Kung Fu.

• 37:24Neil deGrasse Tyson?

  Deflect. Or no, no, no, what's the one where you deflect?

• 37:26Charles Liu?

  Aikido. A wonderful martial art.

• 37:30Chuck Nice?

  All right, here we go. Uh, let's move on to John Laird, who says, what is the single most-

• 37:34Neil deGrasse Tyson?

  John who?

• 37:35Chuck Nice?

  Laird. Laird. Who says, what is the single most mind blowing fact that you could share about the universe in under 30 seconds?

• 37:41Neil deGrasse Tyson?

  Go, Charles.

• 37:42Charles Liu?

  There are so many. Oh, my gosh. Okay, I'll, I'll pick one that's kind of Earth and space sciency that I was recently thinking about. Do you realize that in Earth's atmosphere, a one degree increase in average temperature means that throughout Earth's atmosphere, there is additional energy, just in the heat, floating around our atmosphere, equivalent to more than 100 million atomic bombs? So, when people are asking, what is a one degree increase going to make? What difference is it going to make? The answer is, imagine there are 100 million atomic bombs worth of energy just floating around at any time,

• 38:27Charles Liu?

  creating hurricanes, tornadoes, droughts, floods, you name it, it can happen.

• 38:33Chuck Nice?

  So maybe we should just nuke the hurricanes?

• 38:36Charles Liu?

  Oh, oh, please don't go there. Please don't go there.

• 38:41Neil deGrasse Tyson?

  All right, we gotta go to a lightning round.

• 38:42Charles Liu?

  Okay.

• 38:42Neil deGrasse Tyson?

  We've got a bunch more questions. Okay, Charles?

• 38:45Charles Liu?

  Yes.

• 38:45Neil deGrasse Tyson?

  This is gonna be the 15 second universe.

• 38:48Charles Liu?

  Ooh.

• 38:48Neil deGrasse Tyson?

  Not the 30 second universe.

• 38:49Charles Liu?

  Three second?

• 38:50Neil deGrasse Tyson?

  Go.

• 38:51Chuck Nice?

  All right, 15 second universe. If the universe is infinite, how is it still expanding?

• 38:58Chuck Nice?

  Ooh.

• 38:59Neil deGrasse Tyson?

  Charles, go.

• 38:59Charles Liu?

  Because space and time are not limited by the way we think of space in a box or time on a clock. You can expand continuously as long as you have extra dimensions to work with.

• 39:10Neil deGrasse Tyson?

  Ooh, very nice.

• 39:11Chuck Nice?

  Oh, nice. That was from Craig, uh, at ProTech1 on Twitter.

• 39:14Neil deGrasse Tyson?

  He played the dimension card on that one.

• 39:16Charles Liu?

  There are other ways, too.

• 39:17Neil deGrasse Tyson?

  Yeah, yeah, okay, go.

• 39:18Chuck Nice?

  Oh, okay, here we go. James Thompson wants to know this. If the Earth were flat, would gravitational pull or even satellite orbit be possible? Ooh.

• 39:28Charles Liu?

  Wow.

• 39:29Chuck Nice?

  Ooh.

• 39:29Charles Liu?

  Well, the answer is, if the Earth is flat, but it still has mass, there's still a center of gravity at the middle of the disk.

• 39:36Chuck Nice?

  Right.

• 39:36Charles Liu?

  So you can still have orbits going around. It would just look very differently from where we are.

• 39:40Chuck Nice?

  Yeah, there you go.

• 39:42Neil deGrasse Tyson?

  Very good.

• 39:42Chuck Nice?

  Great answer.

• 39:43Neil deGrasse Tyson?

  Can I add to that?

• 39:44Chuck Nice?

  Yes.

• 39:44Neil deGrasse Tyson?

  Your orbit would have to be sufficiently distant

• 39:46Charles Liu?

  Yeah.

• 39:47Neil deGrasse Tyson?

  from that disk.

• 39:48Chuck Nice?

  Right.

• 39:48Neil deGrasse Tyson?

  So that you didn't really know it was a disk. When you're really close, then you have half the mass on one side relative to the other, and orbits would be very complicated. But the farther away you are from it, the more it looks like just a point of mass to you.

• 40:03Chuck Nice?

  Gotcha.

• 40:04Neil deGrasse Tyson?

  Okay, next.

• 40:04Chuck Nice?

  All right.

• 40:05Neil deGrasse Tyson?

  You okay with that addition?

• 40:06Charles Liu?

  Very good.

• 40:06Neil deGrasse Tyson?

  Charles, okay.

• 40:07Chuck Nice?

  Okay. Wow, here's a great question on the back of what you just said about the disk.

• 40:10Neil deGrasse Tyson?

  Go.

• 40:11Chuck Nice?

  How is it that we know that we're not looking at a galaxy on its side or looking at it face front if it's a disk?

• 40:21Charles Liu?

  Oh, well, if you're looking at a disk galaxy and it's on the edge, it kind of looks like a cigar, right? If you're looking face front on it, it looks like a circle. But then you ask yourself, well, is that an elliptical galaxy? Or is that actually a disk that we're seeing on face? And normally what you do is you have to look to see what the dynamics of the things moving around are. Because if they're swirling and moving in an orderly direction, it's a disk. But if it's moving...

• 40:43Neil deGrasse Tyson?

  Spiral galaxy.

• 40:44Charles Liu?

  Yeah. But if it's moving around in sort of crazy ways, like a hive of bees or something, it's most likely an elliptical galaxy.

• 40:50Neil deGrasse Tyson?

  And we see them at all angles on the sky. So that's why we're pretty, we think we got, we got this one.

• 40:55Chuck Nice?

  You pretty much know what it is.

• 40:56Charles Liu?

  But the question makes an excellent point that you need more information than just what you see in order to make a decision about three dimensions.

• 41:02Chuck Nice?

  There you go. Uh, Judson Doyle wants to know this. I love astronomy because there is always something new to discover. Could it be possible to have undiscovered laws of physics? What?

• 41:13Charles Liu?

  If there were not undiscovered laws of physics, we'd all go home and just have a beer. There absolutely must be laws of physics we have yet to discover. Absolutely.

• 41:23Neil deGrasse Tyson?

  I have a mild rebuttal to that.

• 41:24Charles Liu?

  Go ahead.

• 41:25Chuck Nice?

  No.

• 41:25Neil deGrasse Tyson?

  I do.

• 41:26Charles Liu?

  Please.

• 41:26Neil deGrasse Tyson?

  I do.

• 41:27Charles Liu?

  Go ahead.

• 41:27Neil deGrasse Tyson?

  I do.

• 41:28Chuck Nice?

  Do tell, sir.

• 41:29Neil deGrasse Tyson?

  New laws of physics were all discovered, historically, when there was some phenomenon going on in front of us that we could not explain.

• 41:36Charles Liu?

  Ah, that's true. And there are such things.

• 41:38Neil deGrasse Tyson?

  And so when Faraday moved a wire through a magnetic field, the needle moved. What made that needle move? Oh, he induced a current, you know, thing. Now that's just how we turbines make energy today.

• 41:49Chuck Nice?

  That's how we still make energy.

• 41:50Neil deGrasse Tyson?

  Still make energy.

• 41:50Chuck Nice?

  Right, electricity.

• 41:51Neil deGrasse Tyson?

  We do, we get down into the atom and weird things are happening. There's quantum physics. We, uh, the, uh, objects, when they heated, they radiate, but they're radiating in a way we don't understand. New laws of thermodynamics.

• 42:04Charles Liu?

  Yeah.

• 42:04Neil deGrasse Tyson?

  So I ask you, Charles.

• 42:05Charles Liu?

  Yes.

• 42:06Neil deGrasse Tyson?

  Is there something tabletop on Earth in, happening in front of us that we do not understand? That is waiting for a new law of physics?

• 42:14Charles Liu?

  If by tabletop you mean the universe.

• 42:17Neil deGrasse Tyson?

  Laboratory.

• 42:17Charles Liu?

  If the laboratory, well, there's light, for example, the quantum dual, uh, nature.

• 42:23Neil deGrasse Tyson?

  The duality.

• 42:23Charles Liu?

  Yeah. The, the dual.

• 42:25Neil deGrasse Tyson?

  Particle, wave.

• 42:25Charles Liu?

  Particle duality. There are aspects of some of the quantum behavior of products, uh, subatomic products that come from, um, particle accelerator collisions that are still not quite well understood.

• 42:38Neil deGrasse Tyson?

  You think it needs a new law of physics?

• 42:39Charles Liu?

  It might.

• 42:40Neil deGrasse Tyson?

  Okay.

• 42:40Charles Liu?

  Yeah. And, and I will just say that these days, a laboratory includes the entire universe. And there are plenty of things, dark matter related, dark energy related.

• 42:50Chuck Nice?

  Yeah, man.

• 42:50Charles Liu?

  What do you expect?

• 42:51Neil deGrasse Tyson?

  Okay. Okay. Dark matter, dark energy, could be new laws of physics.

• 42:55Charles Liu?

  Absolutely.

• 42:55Neil deGrasse Tyson?

  Waiting in the wings.

• 42:56Charles Liu?

  Mm-hmm.

• 42:57Neil deGrasse Tyson?

  Go for it.

• 42:57Chuck Nice?

  That's a good, yeah. Okay, here we go. Marcos Cortez wants to know this. Uh, the Earth revolves around the Sun. The Sun revolves around the center of our galaxy. What, if anything, does our galaxy revolve around?

• 43:11Neil deGrasse Tyson?

  Go.

• 43:12Charles Liu?

  We are in the outskirts of what we call the Virgo supercluster. There is a cluster of galaxies called the Virgo cluster, and then around it is this multiply structured, highly diffuse, but really clearly existent glob of material called the Virgo supercluster. Now, our orbit in or around this supercluster is not 100% clear because it's very hard to measure. It's hard to know whether we're going around it, or whether we're going into it, or we're going, you know, sort of somewhere in between. But that's the general answer. The Virgo supercluster center, of which we are part of, but not at the center of.

• 43:47Chuck Nice?

  Okay, okay. All right, now Chuck Nice has to ask a question on the back of that then.

• 43:52Neil deGrasse Tyson?

  Wait, wait, can I add something?

• 43:53Chuck Nice?

  Go ahead.

• 43:53Neil deGrasse Tyson?

  So Earth has been around the Sun about...

• 43:57Charles Liu?

  Four and a half.

• 43:58Neil deGrasse Tyson?

  About a trillion times.

• 43:59Chuck Nice?

  All right.

• 43:59Neil deGrasse Tyson?

  Yeah. Um, so that's not true.

• 44:02Charles Liu?

  Four and a half billion times.

• 44:03Neil deGrasse Tyson?

  Yeah, four and a half billion. It's how many sunrises we've had is about... I counted, it's about a trillion sunrises.

• 44:08Charles Liu?

  Fair enough.

• 44:08Neil deGrasse Tyson?

  Because Earth spun faster earlier. So, but the time it goes around... So, Earth is four and a half billion years old.

• 44:14Chuck Nice?

  Right.

• 44:14Neil deGrasse Tyson?

  The Sun...

• 44:16Chuck Nice?

  Right.

• 44:16Neil deGrasse Tyson?

  Is just not quite old enough to vote, I think if I did my numbers right.

• 44:22Charles Liu?

  In terms of how many times it's gone around?

• 44:23Neil deGrasse Tyson?

  How old it is for its time around the galaxy.

• 44:25Charles Liu?

  It takes 250 million years roughly for the Sun to go around the Milky Way galaxy center one time.

• 44:30Neil deGrasse Tyson?

  And we're five billion years old, so...

• 44:33Charles Liu?

  It's like 18.

• 44:34Neil deGrasse Tyson?

  That would be, yeah, 18, 19.

• 44:35Charles Liu?

  Just...

• 44:36Neil deGrasse Tyson?

  It's not more than 20 years old.

• 44:37Chuck Nice?

  20 years old.

• 44:37Neil deGrasse Tyson?

  20 galactic years old.

• 44:38Charles Liu?

  Wow.

• 44:39Neil deGrasse Tyson?

  But our galaxy has not really finished one orbit around the Virgo supercluster.

• 44:43Charles Liu?

  That's correct.

• 44:43Neil deGrasse Tyson?

  So we're still, uh, an infant in that regard.

• 44:46Chuck Nice?

  Every time we have these conversations, I just get so depressed that you can't be here to see what is going to happen!

• 44:55Charles Liu?

  Oh, it is depressing.

• 44:57Neil deGrasse Tyson?

  Chuck just live forever. We're going to go next one.

• 45:00Chuck Nice?

  All right, here it is. Hemachandran wants to know this. Please tell me what is time?

• 45:08Charles Liu?

  Time is one of those mysteries that maybe laws of physics can improve on. But it can be measured in a bunch of different ways. Cosmically speaking, it can be measured as a motion from order to disorder. That is by the second law of thermodynamics. It can be measured as going from actually disorder to order, where you have a lot of crazy energy going eventually to where you have no background temperature of the universe. Or it could be measured in terms of expansion, like how's it's getting bigger, because that's what we're doing right now. It can be measured, time, that is, as a dimension, like length, width, and height, and tied together in the way that general relativity describes it, as Albert Einstein put it 100-plus years ago. So there are a lot of different ways to describe it.

• 45:51Charles Liu?

  Heck, sociologically speaking, some people even consider time as a resource. We only have a certain number of hours in the day. How do we allocate it properly? So time is one of those cool things where there's a lot of physical depth to it, but there's also a lot of sociological and mental and other kinds of depth to it that's worth thinking about.

• 46:11Neil deGrasse Tyson?

  So who came up with the saying, "Time was invented to make sure everything doesn't happen all at once"?

• 46:17Charles Liu?

  Was that Feynman?

• 46:19Neil deGrasse Tyson?

  I don't know, so somebody clever, one of those.

• 46:23Neil deGrasse Tyson?

  Let's get one more in, one more, ready?

• 46:24Chuck Nice?

  Okay.

• 46:25Neil deGrasse Tyson?

  Give it to him, go.

• 46:28Chuck Nice?

  Abhijit Singh wants to know this.

• 46:29Neil deGrasse Tyson?

  Abhijit.

• 46:30Chuck Nice?

  Abhijit Singh, please tell me how space and time are related. This is something I have trouble understanding.

• 46:38Neil deGrasse Tyson?

  Oh, wonderful.

• 46:39Chuck Nice?

  What I'm sure he means is spacetime.

• 46:44Charles Liu?

  Sure.

• 46:44Neil deGrasse Tyson?

  Yeah, Charles.

• 46:45Charles Liu?

  Well, space and time are related in the same way that length is related to width, or width is related to height. It's another dimension in this four-dimensional thing that's called spacetime. That was described by Albert Einstein's General Theory of Relativity. So length, width, height, and time are the four dimensions of spacetime. The weird thing in that construction is that time only moves forward in our understanding or our experience.

• 47:13Neil deGrasse Tyson?

  Rather, we move forward in time.

• 47:14Chuck Nice?

  In time.

• 47:15Neil deGrasse Tyson?

  Right.

• 47:15Charles Liu?

  We can only move forward in time. We can go forward or backward, or up and down, or left and right, but we can only move forward in time.

• 47:22Neil deGrasse Tyson?

  So we are prisoners of the present, forever transitioning between our inaccessible past and our unknowable future.

• 47:31Chuck Nice?

  Well, with that, I'm just gonna go home and slit my wrist. Thanks! Who knew I was a prisoner?

• 47:38Charles Liu?

  No, we-

• 47:39Chuck Nice?

  No, that's a great saying.

• 47:40Charles Liu?

  We're not prisoners of the present.

• 47:41Chuck Nice?

  I should tweet, I'll tweet that, I'll tweet that. That's a, I love that, that's so poetic.

• 47:45Charles Liu?

  We are not prisoners of the present.

• 47:46Chuck Nice?

  We are.

• 47:47Charles Liu?

  We have been gifted the present.

• 47:49Chuck Nice?

  Ooh.

• 47:50Charles Liu?

  In order to enjoy it to its fullest.

• 47:51Chuck Nice?

  That someone's been through therapy.

• 47:56Charles Liu?

  That's my story and I'm sticking to it.

• 47:57Chuck Nice?

  In Neil's, in Neil's description, I have Stockholm syndrome.

• 48:03Neil deGrasse Tyson?

  I would just add one thing. If you think they're separate, but physicists are forcing you to connect them. You have never met someone at a place without a pre-specified time. Nor have you ever met someone at a pre-specified time without identifying a place. So, once you realize this, the connection between space and time has actually been a fundamental part of our, all of our lives and all of civilization, ever since we've even thought of time. So, I don't say, "I'll meet you at the corner at 33rd and 3rd."

• 48:39Chuck Nice?

  Thanks!

• 48:39Neil deGrasse Tyson?

  When?

• 48:40Chuck Nice?

  Right.

• 48:41Neil deGrasse Tyson?

  "I'll meet you at 10 o'clock."

• 48:42Chuck Nice?

  Where?

• 48:43Neil deGrasse Tyson?

  You know intuitively, it requires space and time to isolate you in this continuum of the fabric of the cosmos.

• 48:51Charles Liu?

  Well said. Well, well said.

• 48:53Chuck Nice?

  Unless you're an intern, in which case you just show up and wait.

• 48:59Neil deGrasse Tyson?

  We gotta call it quits. Chuck, congratulations on the book.

• 49:01Charles Liu?

  Thank you so much.

• 49:02Neil deGrasse Tyson?

  We'll look for it when I finally get a copy of it.

• 49:03Charles Liu?

  Thank you very, very much.

• 49:04Neil deGrasse Tyson?

  To show people, we'll probably put something online.

• 49:06Charles Liu?

  Yes.

• 49:06Neil deGrasse Tyson?

  Yes, exactly. And, always good to have you on, Charles.

• 49:10Charles Liu?

  What a pleasure, thank you so much.

• 49:11Neil deGrasse Tyson?

  And, you know his, his knowledge of superheroes, okay?

• 49:14Charles Liu?

  Yes.

• 49:15Neil deGrasse Tyson?

  It's not that he knows a lot about superheroes. He knows a lot about everything.

• 49:18Chuck Nice?

  Yes!

• 49:20Neil deGrasse Tyson?

  That's just, superhero is just the, is just the index card-

• 49:22Chuck Nice?

  Right.

• 49:23Neil deGrasse Tyson?

  -out of a hundred others.

• 49:24Chuck Nice?

  Right, in the Rolodex.

• 49:25Neil deGrasse Tyson?

  In the Rolodex of stuff this man knows.

• 49:27Chuck Nice?

  Yeah, it's amazing.

• 49:28Neil deGrasse Tyson?

  So, don't be impressed by just the superhero stuff.

• 49:31Chuck Nice?

  Right.

• 49:31Neil deGrasse Tyson?

  You can ask him anything. "How, Charles, why do you know so much about, about old, old TV sitcoms?"

• 49:37Chuck Nice?

  Right.

• 49:38Neil deGrasse Tyson?

  Okay? Well, because I, when I was a kid, I, okay, that, that's, am I, am I wrong?

• 49:43Charles Liu?

  You are very kind.

• 49:44Neil deGrasse Tyson?

  Right.

• 49:44Charles Liu?

  Thank you very much.

• 49:45Neil deGrasse Tyson?

  You got it. Chuck, always good to have you.

• 49:46Chuck Nice?

  Always a pleasure, brother.

• 49:47Neil deGrasse Tyson?

  Dude, alright. This has been StarTalk. Some of you have been watching us, others have been listening. We'll take it both ways. I've been your host, Neil deGrasse Tyson, your personal astrophysicist. And in this special edition of Cosmic Queries, I was delighted to receive your queries. And Chuck did pretty good pronouncing names. All right, we'll catch you next time. As always, keep looking up.