When Black Holes Collide with Nergis Mavalvala

How do we detect ripples in spacetime? Neil deGrasse Tyson and comedian Harrison Greenbaum explore black hole collisions, quantum tricks, and how gravitational waves can help us uncover the early universe with MIT physicist and LIGO researcher Nergis Mavalvala.

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

• 0:00Neil deGrasse Tyson?

  So Harrison, I'm finally getting to the bottom of these gravitational waves.

• 0:04Harrison Greenbaum?

  I brought my gravitational surfboard. I'm ready.

• 0:07Neil deGrasse Tyson?

  I don't know if you can do that. Maybe?

• 0:09Harrison Greenbaum?

  I'm gonna try. I can barely surf in real life.

• 0:13Neil deGrasse Tyson?

  Yeah, so gravitational waves, black hole collisions, the Big Bang.

• 0:17Harrison Greenbaum?

  Sounds like big things.

• 0:19Neil deGrasse Tyson?

  With one of the world's experts on these very subjects.

• 0:22Harrison Greenbaum?

  So excited.

• 0:22Neil deGrasse Tyson?

  A quantum astrophysicist. In a few moments on StarTalk.

• 0:28Neil deGrasse Tyson?

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

• 0:41Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist. I got with me Harrison Greenbaum. Harrison, how you doing, man?

• 0:49Harrison Greenbaum?

  I'm good. Thanks for having me back. I'm so excited.

• 0:50Neil deGrasse Tyson?

  I know. This is not your first rodeo with us. All right. You know what we're gonna talk about today?

• 0:55Harrison Greenbaum?

  Space.

• 0:58Harrison Greenbaum?

  Stars.

• 1:00Neil deGrasse Tyson?

  Gravitational waves.

• 1:01Harrison Greenbaum?

  Ooh.

• 1:02Neil deGrasse Tyson?

  Yeah, I know.

• 1:03Harrison Greenbaum?

  I know about them separately.

• 1:04Neil deGrasse Tyson?

  Oh, gravity and waves?

• 1:05Harrison Greenbaum?

  Yes.

• 1:06Neil deGrasse Tyson?

  But not gravitational waves. I will totally hook you up on that.

• 1:09Harrison Greenbaum?

  All right, great.

• 1:09Neil deGrasse Tyson?

  So Harrison, you're a comedian, and I just learned you have an off-Broadway show.

• 1:13Harrison Greenbaum?

  Yeah, it's called Harrison Greenbaum, coincidentally.

• 1:15Neil deGrasse Tyson?

  Really? I wonder why.

• 1:17Harrison Greenbaum?

  Yeah, exactly.

• 1:18Neil deGrasse Tyson?

  So Harrison Greenbaum.

• 1:19Harrison Greenbaum?

  What just happened?

• 1:19Neil deGrasse Tyson?

  What just happened? It's on stage and it's a performance?

• 1:21Harrison Greenbaum?

  It's a comedy and magic show. I've been working on it for probably-

• 1:24Neil deGrasse Tyson?

  I forgot you do magic.

• 1:25Harrison Greenbaum?

  Yeah, yeah, yeah, yeah.

• 1:26Neil deGrasse Tyson?

  Oh, my gosh. That is so geeky.

• 1:28Harrison Greenbaum?

  Oh, yeah. I went to magic camp and space camp, so I really-

• 1:31Neil deGrasse Tyson?

  So you had no dates going through your entire career at school?

• 1:34Harrison Greenbaum?

  Yeah, my parents wanted breaks for me one week at a time.

• 1:38Neil deGrasse Tyson?

  So our guest today has a different expertise from you.

• 1:42Harrison Greenbaum?

  Really?

• 1:43Neil deGrasse Tyson?

  We have Nergis Mavalvala. Did I say that correctly? Yes. Excellent. And this is your second time on StarTalk. It is. You were last on StarTalk nine years ago. I'm hardly nine years old. Don't, don't, you know. At one of our live performances, StarTalk Live, in a Count Basie Theater in New Jersey. We occasionally take the show on the road, but regionally.

• 2:09Harrison Greenbaum?

  Nice.

• 2:09Neil deGrasse Tyson?

  Yeah, and that was back when our first results from gravitational waves came.

• 2:17Speaker 02

  Yeah, shortly after the first discoveries.

• 2:20Neil deGrasse Tyson?

  Yeah, very, very cool. Well, you are a quantum astrophysicist. That is the baddest assest thing you could ever put on a business card.

• 2:28Harrison Greenbaum?

  I feel like quantum is very small and astrophysics is very big.

• 2:30Neil deGrasse Tyson?

  That's another reason why.

• 2:35Neil deGrasse Tyson?

  You are a professor at MIT. Which department did they put you in?

• 2:37Speaker 02

  Physics.

• 2:38Neil deGrasse Tyson?

  Physics department. That makes sense, doesn't it?

• 2:40Harrison Greenbaum?

  It'd be weird if she was just teaching English.

• 2:44Neil deGrasse Tyson?

  And I'm sorry to learn, you're also dean of the School of Science. Sorry to hear that.

• 2:48Speaker 02

  Yes.

• 2:49Neil deGrasse Tyson?

  Yeah.

• 2:49Harrison Greenbaum?

  Can you get people in trouble?

• 2:51Speaker 02

  I can, but mostly, mostly I get myself in trouble.

• 2:56Harrison Greenbaum?

  Do you cheat on your own test? I have the answer key. It's not fair.

• 3:01Neil deGrasse Tyson?

  So a dean of the MIT School of Science. I say I'm sorry to hear that because that takes time away from like your studies, doesn't it? But they pay you more.

• 3:10Speaker 02

  They do.

• 3:10Neil deGrasse Tyson?

  Yeah, yeah.

• 3:11Speaker 02

  They do. And the other thing that's that comes with being dean is you actually get some administrative help. And as a result, I actually have a little bit more time to be in the lab than when, when I'm just being professor and running around doing too many

• 3:28Neil deGrasse Tyson?

  Trying to get things done. Now you get peep. You got peeps.

• 3:30Speaker 02

  Now I got, I got really, really talented peeps.

• 3:34Neil deGrasse Tyson?

  Okay, all right. That's how that should work. You are on the LIGO team. Let's test Harrison. Harrison, what is, it's an acronym. What does LIGO stand for?

• 3:42Harrison Greenbaum?

  Lord, I got options.

• 3:47Harrison Greenbaum?

  Is that, that works?

• 3:50Neil deGrasse Tyson?

  Nergis, I think that should be the new meaning of the, of the acronym LIGO.

• 3:55Speaker 02

  You know, there's a lot of changes coming to NSF proposals. That could be one of them.

• 4:00Neil deGrasse Tyson?

  Lord, I got options. Laser Interferometer Gravitational Wave Observatory. Did I get that correct?

• 4:07Speaker 02

  You did. You did.

• 4:08Neil deGrasse Tyson?

  Very good. And you're on the team that discovered these. So I understand they took a bunch of people to Stockholm for the Nobel Prize. Were you on, on that plane?

• 4:17Speaker 02

  Yes.

• 4:18Neil deGrasse Tyson?

  Excellent. She got all dressed up and everything?

• 4:20Speaker 02

  I kind of, yeah. Yeah. No, that's not my favorite.

• 4:23Neil deGrasse Tyson?

  What, what, what outfit would you have for some other occasion if not for the Nobel Prize?

• 4:29Speaker 02

  You know, I'm not a dress up type. And so, and, and, and, and I'm not a girly type, so they had to also decide, am I gonna wear like girly clothes or a tux?

• 4:38Neil deGrasse Tyson?

  Oh, you fell into a, a, a, a haberdashical gap.

• 4:42Speaker 02

  Yeah, a sartorial dilemma.

• 4:44Neil deGrasse Tyson?

  Sartorial, okay.

• 4:47Neil deGrasse Tyson?

  Interesting, not there.

• 4:49Harrison Greenbaum?

  So what did you end up doing? Just shorts?

• 4:54Harrison Greenbaum?

  I feel like that's the answer.

• 4:56Neil deGrasse Tyson?

  The king of Sweden is cool with that.

• 4:59Neil deGrasse Tyson?

  No, so I'm delighted that you got to see that. By the way, we just had on StarTalk, I hung out with Kip Thorne, the man himself, and we visited him at his home. And we gave, had a whole interview. It was largely about, you know, he was one of the executive producers on the film Interstellar.

• 5:17Harrison Greenbaum?

  Wow.

• 5:17Neil deGrasse Tyson?

  And it just had its 10th anniversary and it was a re-release, just in celebration of that fact. Because it had so many people talking about gravity physics and relativity and, and all the rest of that. So, anything out there that sort of ratchets up people's fluency in physics, I'm all for it. Well, even if they didn't understand what the hell they were looking at.

• 5:36Harrison Greenbaum?

  I was like, Matthew McConaughey, I think he's aging, I'm not sure. The thing with the daughter.

• 5:40Neil deGrasse Tyson?

  Yeah, the daughter and the thing, yeah, so that, we, we covered that. But let's get back to gravitational waves. You reminded me, I'd forgotten, that when we were on stage, we actually did a gravitational wave together.

• 5:54Speaker 02

  The gravitational wave danced.

• 5:56Neil deGrasse Tyson?

  Danced.

• 5:57Speaker 02

  Yes.

• 5:58Neil deGrasse Tyson?

  Yeah, I, I don't, I don't know if we have footage of that, but I hope not.

• 6:03Speaker 02

  Me too.

• 6:04Harrison Greenbaum?

  I'm trying to picture it.

• 6:06Neil deGrasse Tyson?

  So, Nergis, remind everybody, we've heard the term gravitational waves or ripples in spacetime. That's surely accurate, but I don't know that it helps. So how can you dig into that and unpack what's going on?

• 6:22Speaker 02

  Yeah, so I think one of the ways we, we can think about that is, it's very tempting to look out into space and think of empty space as A number of things that are just aren't true. Space isn't empty. Space doesn't do nothing. It actually has many, many dynamical properties. Things that like it can curve. It can ripple. It can tear. And so that's really the wavy part of spacetime. And the idea is, is that when we have objects that are massive, so they should have gravity. And if they just-

• 6:55Neil deGrasse Tyson?

  When you say massive, you don't mean a brick or a stone. You're talking about black holes.

• 7:00Speaker 02

  Well, you know, bricks and stones would do the same thing, except it would be just a much, much smaller effect.

• 7:06Neil deGrasse Tyson?

  And harder to measure.

• 7:07Speaker 02

  A way, way harder to measure.

• 7:08Neil deGrasse Tyson?

  So our threshold is for what? I mean, our measuring threshold today?

• 7:11Speaker 02

  Our measurements thresholds today are not even ordinary stars like our own sun.

• 7:17Neil deGrasse Tyson?

  Couldn't measure that.

• 7:17Speaker 02

  I know. So if we're looking for waves from, from these kinds of objects, they're more things like neutron stars and black holes.

• 7:24Neil deGrasse Tyson?

  So dense objects in the universe?

• 7:26Speaker 02

  Dense objects.

• 7:26Neil deGrasse Tyson?

  Where gravity is, is saying something.

• 7:28Speaker 02

  Yeah, so objects that have so much gravity packed into a small volume that really the space around those objects is very bent.

• 7:38Neil deGrasse Tyson?

  Okay. Have those objects tried Ozempic?

• 7:44Neil deGrasse Tyson?

  Oh, oh, oh. How do we end up doing, doing a commercial for a pharmaceutical company? And without getting paid for it? We're helping the black holes slim down a little bit. They're very dense. They're causing waves and gravity. That's actually-

• 7:56Speaker 02

  We don't want them to slim down.

• 7:58Neil deGrasse Tyson?

  For their work. But actually, isn't Hawking radiation a kind of Ozempic for black holes?

• 8:05Speaker 02

  Yeah, it'll help them evaporate.

• 8:07Neil deGrasse Tyson?

  Yeah, so we got a little mechanism. So tell everybody about Hawking radiation.

• 8:11Speaker 02

  So Hawking radiation, it comes about from the quantum mechanical properties of, of black holes. So the idea is that in quantum mechanics, we have a phenomenon where particles and antiparticles can, can be formed out of photons. And then they can crash together and become photons again. And Hawking radiation-

• 8:31Neil deGrasse Tyson?

  It's energy to matter, matter back to energy. That equals mc squared would prescribe how much of that is happening?

• 8:36Speaker 02

  Right.

• 8:37Neil deGrasse Tyson?

  In any moment, okay?

• 8:38Speaker 02

  And Hawking-

• 8:38Neil deGrasse Tyson?

  E on one side. M on the other side, so we good. And then C is speed of light? Speed of light squared.

• 8:44Speaker 02

  Yeah.

• 8:44Neil deGrasse Tyson?

  Yeah, okay.

• 8:45Speaker 02

  And so this is a phenomenon by which as you create these particles, some of that energy can get radiated away. Where does that energy come from? It comes from the properties of the gravitational properties of the black hole. What happens?

• 9:02Neil deGrasse Tyson?

  So you're stealing gravity, matter, out of the black hole and thereby taking away some of its gravity?

• 9:07Speaker 02

  Yes.

• 9:07Neil deGrasse Tyson?

  Okay. And it just does that. And so it's a very slow version of Ozempic for black holes. That's what started this.

• 9:14Speaker 02

  Very, very slow.

• 9:15Neil deGrasse Tyson?

  Finish it there. Right, okay.

• 9:17Speaker 02

  Yeah.

• 9:17Neil deGrasse Tyson?

  All right. So, Nergis, can I take you back to when I was 14? All right? I came to the Hayden Planetarium. Here's my office here. I became director of the planetarium. I came here as a kid. Not at 14. No, no, no. No, ultimately, I became director. So I came here and I, beyond that space show that I watched at the time, they would have programs at night, which we still do. And with speakers would come in and give lectures on modern astrophysics. So I would come in for that. And one of them was on black holes. That's when I first learned that gravity moves at the speed of light.

• 9:56Speaker 02

  You knew that when you were 14? I didn't learn that till I was much older.

• 10:01Neil deGrasse Tyson?

  That's when I learned it. That's when I learned it. 50. And then I thought about it and I said, if gravity travels at the speed of light, then how does gravity get out of a black hole? And the answer was a little fishy to me. They said, well, there's a gravitational field that's always there. And it's a change in the gravitational field that moves at the speed of light.

• 10:34Neil deGrasse Tyson?

  I don't know if that's accurate, but that's what the dude told me. And otherwise, he couldn't get gravity out of a black hole, where the black hole doesn't let anything get out, even the speed of light, and that the gravity moves at the speed of light. How's the gravity gonna get out of a black hole?

• 10:49Speaker 02

  I just don't think of it that way. I, I think about gravity as the geometry of, of spacetime. And the black hole is part of that geometry. And the things that we can know about, and this is true for light as well, are only things that are outside the horizon of the black hole. So what I've always been taught, and I think I learned this maybe even from Keith Thorne, uh, was that you, it's not meaningful to think about what happens inside the horizon, because we don't even know if our laws of physics would hold there or not. And so when I think about gravity traveling at the speed of light, what's actually traveling at the speed of light is a gravitational wave.

• 11:30Speaker 02

  And it's only really meaningful outside of the horizon.

• 11:35Neil deGrasse Tyson?

  She dodged that one. Yeah. We can't know what's in there, so who cares? She totally dodged that. No, no, that's good, that's good. That's, it's an important distinction that physics had to mature into as a field, to realize there are things that are beyond your knowledge, and therefore you, there's nothing you can say about it.

• 11:53Speaker 02

  Right.

• 11:54Neil deGrasse Tyson?

  At all.

• 11:55Speaker 02

  Uh, for now, I, you know, who knows which, what other forces we might discover that would describe something inside that horizon.

• 12:03Neil deGrasse Tyson?

  Okay, but right now, that's not, not happening.

• 12:05Speaker 02

  Right.

• 12:05Neil deGrasse Tyson?

  Okay, so, but a change in gravity would then be a ripple, a change in that sort of thing that I'm feeling out there.

• 12:12Speaker 02

  Right.

• 12:13Neil deGrasse Tyson?

  And, and we can just watch that at the speed of light. Because we'd say, if we plucked the sun from the center of the, of our solar system, you wouldn't know about it for eight minutes and 20 seconds. You'd still orbit, we'd still feel the heat, we'd still feel the gravity, everything would be normal. And then eight minutes, 20 seconds later, we fly off at a tangent in the dark.

• 12:31Speaker 02

  Right.

• 12:31Neil deGrasse Tyson?

  And freeze in interstellar space. Have a nice day.

• 12:36Neil deGrasse Tyson?

  How that's gonna happen. Those eight minutes before are amazing.

• 12:49Speaker 03

  Hello, I'm Alexander Harvey and I support StarTalk on Patreon. This is StarTalk with Dr. Neil deGrasse Tyson.

• 13:06Neil deGrasse Tyson?

  Did Einstein, I don't know that I've seen the paper that did this, did he predict gravitational waves?

• 13:12Speaker 02

  Yeah, so Einstein, when he was developing the theory of general relativity, and this was the theory of gravity. So the thing that, so we all learn in school, Newton's version of gravity, and Newton's law has been, it's easy to understand, it's intuitive, it says you have two objects that have mass, and they're gonna feel a force of attraction between them, and it was quite quantitative. He said the force of attraction will be proportional to their masses, and inversely proportional to the square of the distance separating them.

• 13:42Neil deGrasse Tyson?

  It's very clean, that's a clean operation.

• 13:44Speaker 02

  You know, we teach it in very early, sort of, first encounters with physics, and it was quite successful, it told us about how orbits would work, and it also had, pretty early on, places where it didn't work perfectly. Now, what Einstein, when he was formulating, thinking about gravity, he kind of turned it on its head, and he said, "Well, look, gravity's not really a force. Gravity is the geometry of spacetime." Big words. But he had a series of papers, two or three, from 1915 to 1918, in which he sort of formulated this theory of general relativity.

• 14:26Speaker 02

  He wrote down what are now known as Einstein's equations. They look not that much worse than, say, Newton's law, except they're quite beastly, they're very difficult to solve. But part of that work was that he did ask the question, "What happens if whatever object you're thinking of isn't just sitting still in space? What happens if it's moving?" And not just moving at constant velocity, what happens if it's accelerating? And then, out of his equations popped this wave-like object, which he called gravitational waves, and, and the other thing is-

• 15:06Neil deGrasse Tyson?

  You know, I want stuff like that to pop out of my equations. Do you have equations when stuff pops out?

• 15:12Harrison Greenbaum?

  No.

• 15:14Speaker 02

  Look, me neither.

• 15:17Harrison Greenbaum?

  I'm still stuck on the wave part.

• 15:19Neil deGrasse Tyson?

  The wave part, okay.

• 15:20Harrison Greenbaum?

  Was he gravitational surfing?

• 15:23Speaker 02

  I have a lot of analogies to that, because if you wanted to try and visualize what would this look like, one way that you could is you could think of spacetime as the surface of a still pond. And you drop a big rock in the middle, and there's a wave that travels, a ripple that travels on the surface. It travels outwards from where you dropped the rock. And if you were a little teeny tiny ant on a surfboard, you would surf that wave, right?

• 15:48Neil deGrasse Tyson?

  And the wavelength, so the distance between the crests,

• 15:51Speaker 02

  Right.

• 15:52Neil deGrasse Tyson?

  would be related to how big was the rock that you dropped in?

• 15:55Speaker 02

  Exactly, right.

• 15:56Neil deGrasse Tyson?

  Okay, so when you measure gravitational waves with LIGO or whatever other tools available to you, you try to measure the wavelength of that so that you can infer what created that wave. Because you don't, otherwise, you didn't see the thing happen.

• 16:10Speaker 02

  No, exactly, right. So we measure a number of things. We measure the wavelength, which is the spacing between the peaks, successive peaks. We also measure the amplitude, which is how big, what was the height of the wave.

• 16:23Neil deGrasse Tyson?

  Mm-hmm.

• 16:23Speaker 02

  And those, both of those things are changing with time, depending on what the source is. So by measuring sort of the shape of the wave,

• 16:33Neil deGrasse Tyson?

  As you go into it and as you come out of it.

• 16:35Speaker 02

  As it passes by you.

• 16:37Neil deGrasse Tyson?

  As it washes over the earth.

• 16:39Speaker 02

  Exactly. And as you do that, you can tell many, you can infer some of the properties of the system that emitted that wave. Sort of like if you just saw the ripple at the edge of the pond, and you have to kind of measure the frequency of the wave, you have to measure the amplitude of the wave, you have to know something about the density or the viscosity of the water that, of the pond.

• 17:04Neil deGrasse Tyson?

  That's right, because the medium, it would come through differently.

• 17:07Speaker 02

  Right. And once you have put those things together, without ever seeing the rock fall in the center of the pond, you can say something about the rock. And that's kind of what we're trying to do.

• 17:16Neil deGrasse Tyson?

  So that's very impressive, because you can, you get this measurement. And then out in the research papers, these are two black holes of thirty times the mass of the sun colliding a billion light years away. I mean, that's badass to make that kind of statement.

• 17:30Speaker 02

  It is. I think that the properties of the black holes are almost, I can't think of too many things that are more badass than that.

• 17:38Neil deGrasse Tyson?

  I agree.

• 17:39Speaker 02

  I have to tell you why. I mean, so, you know, one of the first gravitational waves that we measured with LIGO were from these thirty solar mass black holes. And you know what these monsters were doing? At the time that they collided, they were moving at half the speed of light.

• 17:56Neil deGrasse Tyson?

  Whoa.

• 17:57Speaker 02

  Okay. I just...

• 18:00Speaker 02

  You are speechless.

• 18:01Harrison Greenbaum?

  I'm trying to picture. I don't know if I can actually picture what that... I'm picturing a Godzilla movie. It's like a black hole with like little arms and legs. And they're both fighting each other. But instead of the city, it's space. That's where my brain is going.

• 18:15Speaker 02

  And instead of, you know, moving at sort of human or Godzilla speeds, they are moving at the speed of light. The amount of energy it takes to accelerate a little electron in our sort of, you know, experiments to the speed of light and to think we do it with something that's thirty times the mass of our sun.

• 18:36Neil deGrasse Tyson?

  So there's no greater particle accelerator than the universe itself?

• 18:40Speaker 02

  Indeed.

• 18:41Neil deGrasse Tyson?

  Ooh.

• 18:43Harrison Greenbaum?

  Is it making a sound when it happens?

• 18:46Speaker 02

  No. And the reason is that...

• 18:49Neil deGrasse Tyson?

  But wait a minute, you guys put a soundtrack to that wave.

• 18:52Speaker 02

  That's different than whether it made the sound.

• 18:55Neil deGrasse Tyson?

  Then get us out of that little, that media ploy because I always have to undo things that the media does or give context for it. Because people say, well, if space is a vacuum and because they knew that sound doesn't...

• 19:08Harrison Greenbaum?

  Right in space, no one can hear you scream.

• 19:09Neil deGrasse Tyson?

  Exactly. That's a legit call, right, for the movie, Alien. Alien. So, did you endorse this attachment of sound to it? How did you, as an educator and as a physicist, where were you on that?

• 19:22Speaker 02

  Yeah, so you know, I think of it as there are many, many phenomena as scientists or as humans and observers that we can't directly observe. Let's take light. So we love to look at pictures of even astronomical objects where they're emitting X-rays. We can't see X-rays, so we color it blue. And we can see blue and then the object looks blue and we imagine that's an X-ray. And so when I think about sound or the sound of these, you know, waves, it's an encoding. It's a way of of mapping it onto senses that we do have.

• 19:56Neil deGrasse Tyson?

  Okay.

• 19:57Speaker 02

  Right? So that's how, you know, because otherwise.

• 20:00Neil deGrasse Tyson?

  That's fair enough.

• 20:01Speaker 02

  You know, so I mean, I think about the way that we visualize a cell. We can't just look at a blob of stuff and say that, you know, that's the cell. We've used microscopes, we've used ways of observing, and then we put together a picture.

• 20:14Neil deGrasse Tyson?

  We've enhanced our feeble senses.

• 20:16Speaker 02

  Exactly.

• 20:17Neil deGrasse Tyson?

  To gain access to the universe that would otherwise lay forever invisible in plain sight.

• 20:22Harrison Greenbaum?

  But it's dangerous because if you pick the wrong sound, then nobody cares. Like, if you make a video of two black holes colliding and it goes.

• 20:28Neil deGrasse Tyson?

  Boing.

• 20:29Harrison Greenbaum?

  Exactly. You gotta pick the right sound.

• 20:32Neil deGrasse Tyson?

  Something out of a Tom and Jerry cartoon.

• 20:35Harrison Greenbaum?

  Exactly.

• 20:36Neil deGrasse Tyson?

  A ruka.

• 20:37Harrison Greenbaum?

  It doesn't work.

• 20:40Neil deGrasse Tyson?

  So with LIGO, all's well that ends well, but it didn't begin smoothly. I remember there were physicists called to Congress to defend the budget outlay to the National Science Foundation that was going to take huge chunks of money to pay for your laser toy.

• 20:57Harrison Greenbaum?

  How did you convince them you weren't building a Death Star?

• 21:00Speaker 02

  Yeah, so a couple of things. It is certainly part of the history of LIGO that, so what I know of the history is that Ray Weiss and Kip Thorne, two of the founders of LIGO, Ray Weiss was an experimentalist thinking about how you might measure gravitational waves.

• 21:18Neil deGrasse Tyson?

  And he shared the Nobel Prize.

• 21:19Speaker 02

  Right, and they shared the Nobel Prize. And Kip Thorne was thinking about the astrophysics. What would gravitational waves look like if two neutron stars or black holes collided? And they met somewhat accidentally in 1975. The story goes that they they had to share a hotel room because one of their bookings got messed up. And then they were up all night conjuring up. How one would make this measurement. And that's where the concept of this four kilometer long detector, two and a half mile long detector, LIGO, was born.

• 21:52Neil deGrasse Tyson?

  What intrigues me here is, at the time, because I remember, because I'm that old, there was someone at the University of Maryland, Joe Weber, who was building a gravitational wave detector. And it was a cylinder of aluminum with very highly sensitive servos, if that's the word, that monitored the position of this slab of aluminum. And if a gravitational wave washed over it, it would jiggle it in such a way that he would then measure it by way of these servos. So this method, conjured in the wee hours of the morning in a hotel room, is a completely different method.

• 22:29Speaker 02

  Correct.

• 22:29Neil deGrasse Tyson?

  And maybe, there's no way you could have detected it with a slab, a cylindrical slab of aluminum.

• 22:35Speaker 02

  I think now, in hindsight, we can say that would have been quite, I mean, we haven't done that yet, right?

• 22:41Neil deGrasse Tyson?

  Yes, okay.

• 22:41Speaker 02

  So it is true that Joe Weber at the University of Maryland had this big slab of metal, and it was instrumented with sensors that would see this big slab of metal ringing, just like if you hit a wine glass and it sort of rings a tone. So it would ring because of the gravitational wave that went through it. Now, it turned out that Weber's claim, people, so when Weber made the claim, a lot of people started to build similar instruments and to try to reproduce the measurements, and they couldn't. And eventually, people just didn't believe it.

• 23:14Neil deGrasse Tyson?

  If I remember correctly, he had a paper saying he had a measurement.

• 23:17Speaker 02

  He had a measurement, and if I recall correctly, the claim was, "We have a measurement, and not only do we have a measurement, but it seems like the wave is coming from the center of our galaxy", which was sort of seen as a preferred location for some gravitationally heavy object like a black hole. But people just couldn't reproduce it. But what it did do is it really sparked interest in the topic. And so a large number of people started to build these, and they weren't making a measurement.

• 23:48Neil deGrasse Tyson?

  Not all known results are bad, if they stimulate interest, is the lesson there.

• 23:52Speaker 02

  I think that's right, and even in Weber's case, though, eventually, it turned out...

• 23:58Speaker 02

  To be incorrect claims, he invented some techniques that even to this day, we still, we still use.

• 24:06Neil deGrasse Tyson?

  Okay, you mentioned something very important about science. One researcher's result does not make the truth.

• 24:14Speaker 02

  Yes.

• 24:15Neil deGrasse Tyson?

  You need verification. Because anything could have, they could be biased, their current could have fluctuated. Anything could have happened in one case, but if you have two, three, four, and if they give the same result, you got something good. If nobody can match the result, it's time to move on.

• 24:30Speaker 02

  That's right. And in Weber's case, I think it was even more interesting because he had two of these bar detectors, and it was only when people built third, fourth, fifth, and they were built with slightly different technologies, and perhaps even with slightly different expectations, that it was understood that no one was reproducing what Weber was saying.

• 24:52Neil deGrasse Tyson?

  So now, in LIGO, when you made your grand announcement, two black holes colliding, why should we believe you?

• 24:59Speaker 02

  Good question.

• 25:00Neil deGrasse Tyson?

  Because, is there another LIGO to check what you did?

• 25:02Speaker 02

  Yes.

• 25:03Neil deGrasse Tyson?

  Oh, there it is. How many of these lasers are there? Okay, yes, there is. Next, we're done there? Nice. No, there was foresight there, of course. The LIGO facility I visited was in Louisiana, outside of New Orleans, but you would have a whole other one if that one LIGO facility makes a detection. You would presume and expect another LIGO to make the detection as well.

• 25:29Speaker 02

  Correct.

• 25:30Neil deGrasse Tyson?

  Not necessarily in the same moment, separated by...

• 25:34Speaker 02

  Almost certainly not in the same moment, because there's another LIGO facility in Washington State, east of Seattle, and you can think about, sort of, if you think about a wave that's coming through the earth, a gravitation wave does that, if a gravitation wave is emitted by some distant source, light is actually quite difficult for astronomers, because light coming to us interacts with everything in between. Gravitational waves just pass through most things.

• 26:00Neil deGrasse Tyson?

  Ooh.

• 26:01Speaker 02

  So they are quite useful.

• 26:02Neil deGrasse Tyson?

  You have a pure expression of what happened at its source.

• 26:05Speaker 02

  Yes, but it's a double-edged sword, because by the same, you know, token, it doesn't interact very strongly with our detector either, so it's really pretty darn weak.

• 26:15Neil deGrasse Tyson?

  Be careful what you wish for. Right, right. This gravitational wave sounds rude. So the one in Washington, it's Hanford, I think, is that the one?

• 26:22Speaker 02

  Yes, in Hanford, Washington.

• 26:24Neil deGrasse Tyson?

  Washington, which I think used to be a place where they purified...

• 26:28Speaker 02

  Plutonium.

• 26:28Neil deGrasse Tyson?

  Yeah.

• 26:29Speaker 02

  Yeah.

• 26:30Neil deGrasse Tyson?

  So, are you giving emotions to the gravitational wave? You're declaring it's rude.

• 26:35Harrison Greenbaum?

  Yeah, the gravitational wave just walks through the party, says hi to nobody.

• 26:37Neil deGrasse Tyson?

  Nobody, right.

• 26:40Speaker 02

  Yes, you know, that is one of... So if you ask, one of the things that we haven't observed with gravitational waves is gravitational waves from the very early universe. Say, right after the Big Bang. And when we think about what we know about the Big Bang...

• 26:55Neil deGrasse Tyson?

  But just to be clear, you haven't observed them because you don't have the capacity to do so yet.

• 27:00Speaker 02

  Yes, our instrumentation just isn't sensitive enough.

• 27:03Neil deGrasse Tyson?

  Okay.

• 27:03Speaker 02

  Yeah. So, if you think about what we know about the Big Bang, what we know comes from light. Now, the light that we see from the Big Bang, this cosmic microwave background, actually comes to us from 400,000 years after the Big Bang. Now, what happened before that, we can't tell, because the universe was so hot and dense at the time, that the light couldn't escape. Now, what does that mean? It's exactly what you were saying, Harrison. So, the light is like going to a party with an extrovert. And you say, "Honey, I'm ready to leave." And it'll be an hour before you leave the party, because they're gonna stop, they're gonna say hi to people on the way to saying bye to people.

• 27:44Neil deGrasse Tyson?

  And top off their drink.

• 27:45Speaker 02

  Yeah, exactly. And they're not coming. Gravitational waves from the early universe have been streaming to us. If we could measure them in the LIGO band, they would be streaming to us from when the universe was 10 to the minus 22 seconds old. And the reason is just what you said. They're like going to the party with the introvert. You say, you know, "We're ready to leave." And you're lucky if they'll say goodbye to the host.

• 28:12Neil deGrasse Tyson?

  Right. So, this distinguishes our access to the early universe from what our normal telescopes can bring to us, which is this 400,000-year barrier, really. And the gravitational waves, which just plow right past that. They don't even care. They're moving right along.

• 28:31Speaker 02

  Right. And so, if you want to see the earliest moments of the universe, gravitational waves are your friend.

• 28:39Harrison Greenbaum?

  If we want to make them more sensitive, do we have to live with bigger lasers?

• 28:42Speaker 02

  That's a piece of it, but there's lots of other things you've got to make better, too.

• 29:05Neil deGrasse Tyson?

  I'm in conversation with Kip Thorne and I verified, because I'd read this, but he's the man, and I said, "You have all this apparatus, four meter, four kilometer long beam that reflects and they recombine, you look at a phase shift and look at a jiggle." And I said, "How big is that jiggle? How much did this apparatus move by virtue of this wave passing across?" And it is the width of one-twentieth the diameter of a proton. When it's cold, when it's nice outside.

• 29:43Speaker 02

  No, that's too big.

• 29:46Neil deGrasse Tyson?

  Too big? Wait, so, all right, so, so, so, let's just speak more broadly, a fraction the diameter of a nucleon of an atom, okay?

• 30:00Speaker 02

  A thousandth.

• 30:01Neil deGrasse Tyson?

  Okay, so, you want to make sure nothing else is responsible for what you're about to measure, otherwise you're measuring the wrong thing. And when I visited, they were telling me, if somebody's walking down the street, a mile away, those vibrations can be detected, and that's exactly how they described it, but they see all, so they have to isolate the experiment from anything that could be happening from the outside, okay? So then you isolate it, and then you put it in a vacuum so that air particles are not bumping into it. So now it's there, but then, it is at a temperature. It's not at absolute zero, so at any temperature, all, everything is vibrating.

• 30:44Neil deGrasse Tyson?

  And even if you tamp that down, there's always a quantum uncertainty about the position of a particle. Heisenberg told us this, okay? So, if you want to know exactly what a particle is doing, there's an uncertainty to that. So how are you making measurements that are smaller than the quantum uncertainty allows? And I, we had this conversation, and Kip Thorne said, "Well, we did blah, blah, blah, and we did this, and in that way, we cheated the quantum laws." And I said, "No, no!"

• 31:20Neil deGrasse Tyson?

  Then it's not a law if it bends at your will. So what was he talking about?

• 31:25Speaker 02

  Yeah, we do that.

• 31:26Neil deGrasse Tyson?

  No, the fact, no! That's not an answer!

• 31:31Neil deGrasse Tyson?

  So this is like Invasion of the Body Snatchers. Yes, he's one of us.

• 31:36Neil deGrasse Tyson?

  I think it's like one of us. We both can bend the rules of quantum physics. So, okay, for those of you who have such powers, please explain to me.

• 31:46Speaker 02

  Yeah.

• 31:47Neil deGrasse Tyson?

  It like, in its plain as English as you can.

• 31:49Speaker 02

  Yeah, so let me, let me, I can try to do that. So what quantum mechanics tells us is that if you measure two particular properties of a particle, and in, in, in one example would be the energy of, let's talk about photons, because it turns out in LIGO at the moment, we're limited by the quantum mechanics of the light. The quantum mechanics of the mirror isn't yet a problem, because the mirrors are still moving more than their quantum properties would allow. Okay, so let's, let's talk about the light. So, uh, the quantization of the light says a light has two properties. Light's made up of photons. And if I want to make a measurement of that, I want to know two things about it. What was the energy of the photons that I'm measuring? And when did they arrive on my detector?

• 32:34Speaker 02

  And you can't know those two things at the same time with infinite precision.

• 32:39Neil deGrasse Tyson?

  With perfect.

• 32:40Speaker 02

  Exactly, with perfect knowledge. But you can know one of those properties very, very well if you allow the other one to be very unknown. That quantum mechanics allows you to do. That's the trick we play. So if we are interested, as we are in our measurement, measuring the phase of the light wave.

• 33:00Neil deGrasse Tyson?

  The phase would be, because you have two light beams.

• 33:03Speaker 02

  Right.

• 33:03Neil deGrasse Tyson?

  And you have to see how they match up.

• 33:04Speaker 02

  That's right.

• 33:05Neil deGrasse Tyson?

  Because if they match up perfectly, nothing happened to one relative to the other.

• 33:09Speaker 02

  Right.

• 33:09Neil deGrasse Tyson?

  Gotcha. But if, if, if a wave washes over, then one jiggles a little differently and you will, the waves don't match up. The, the, you'll see the, yeah, okay.

• 33:18Speaker 02

  Right. That's exactly right. So say if you're interested in, in measuring the phase, then what you can do is you can create light with properties where you let the amplitude or the energy of, of, of the wave be very unknown, but you've, you've traded off, traded that off for precision in the phase. And we have learned how to make instruments that can do that.

• 33:42Neil deGrasse Tyson?

  Damn.

• 33:43Harrison Greenbaum?

  So they're instruments that increase uncertainty.

• 33:46Speaker 02

  They do.

• 33:47Neil deGrasse Tyson?

  In one variable.

• 33:48Speaker 02

  That's right.

• 33:49Neil deGrasse Tyson?

  And.

• 33:50Speaker 02

  And reduce it in the other variable. And that's really important. If you were reducing the quantum uncertainty in both variables at the same time, you would be violating the laws of physics. But that we are not doing.

• 34:03Neil deGrasse Tyson?

  Okay, you're just bending the laws.

• 34:05Harrison Greenbaum?

  Yeah. So we're not breaking the laws at all?

• 34:07Neil deGrasse Tyson?

  No, no, it's a fair bit of loophole.

• 34:08Speaker 02

  I like to say.

• 34:09Neil deGrasse Tyson?

  This is a quantum loophole. Admit it.

• 34:11Speaker 02

  What? No.

• 34:16Neil deGrasse Tyson?

  Oh, she got angry. She got a couple of attitude on that one.

• 34:19Harrison Greenbaum?

  So much for increasing the uncertainty.

• 34:21Speaker 02

  I call it manipulating the laws of quantum physics because we can't violate them. And loopholes are things that are just usually things you haven't thought of.

• 34:33Neil deGrasse Tyson?

  Yeah.

• 34:33Speaker 02

  Whereas this we've thought of. We're deliberately doing this and, you know, so that's the kind of things.

• 34:39Neil deGrasse Tyson?

  So it's not a problem if you don't know at all what the.

• 34:44Speaker 02

  So there's a price to pay.

• 34:46Neil deGrasse Tyson?

  Yeah.

• 34:46Speaker 02

  The price to pay is, look, if you're interested in measuring the phase, and if by accident, because your measurement apparatus isn't perfect, you start to collect a little bit of information about the altitude, it won't work for you anymore. Because remember, the altitude is now very, very noisy.

• 35:02Neil deGrasse Tyson?

  Wow, okay.

• 35:03Speaker 02

  So this is what we do. We reduce the noise in the quantity we're most interested in measuring. We stuff it into the quantity we're trying not to measure.

• 35:12Neil deGrasse Tyson?

  Okay.

• 35:12Speaker 02

  And then we try to do it as well as we can.

• 35:14Neil deGrasse Tyson?

  Grabbing quantum physics by the horns.

• 35:16Speaker 02

  Yes.

• 35:17Neil deGrasse Tyson?

  And making it bend to your will.

• 35:19Speaker 02

  You know, almost. We call it squeezing. We squeeze the light.

• 35:23Neil deGrasse Tyson?

  Ooh. Let's get the picture of this now. You have two beams.

• 35:26Speaker 02

  Yeah.

• 35:27Neil deGrasse Tyson?

  They're at right angles, I presume.

• 35:28Speaker 02

  Yeah.

• 35:29Neil deGrasse Tyson?

  Yes. And the round trip is eight kilometers? Is that right?

• 35:33Speaker 02

  Yeah.

• 35:34Neil deGrasse Tyson?

  Okay. And so it takes time for the very measured time for the light to do that. This is a single laser beam of light that has been split, correct?

• 35:44Speaker 02

  It has been split and not only does it go four kilometers down and come back, there's an added complication, if you will, which is that in that four kilometer span, we have a pair of mirrors that are facing each other. And just like when you put your own head between two mirrors and you see multiple images, the light is bouncing multiple times between those. It's a way of increasing the path length, if you will.

• 36:10Neil deGrasse Tyson?

  Alright.

• 36:11Speaker 02

  So, and so it bounces, in our case, in Lagos, it's about a hundred times.

• 36:15Neil deGrasse Tyson?

  Okay.

• 36:16Speaker 02

  So.

• 36:16Neil deGrasse Tyson?

  But then it has to come back through to recombine.

• 36:20Speaker 02

  Yes.

• 36:20Neil deGrasse Tyson?

  Okay, so you have your magic waves that you, it goes up and back a hundred times. Then, at some point, the light has to come back through and not reflect back.

• 36:28Speaker 02

  Correct.

• 36:29Neil deGrasse Tyson?

  And then you compare the waves of the light.

• 36:33Speaker 02

  From the two arms, yeah.

• 36:35Neil deGrasse Tyson?

  So, that's the shift. So how much different would one wave have to be from the other to be the gravitational wave, to be the effect of the gravitational wave?

• 36:47Speaker 02

  Yeah, so, so the way that you can think of it is that the output of our instrument, we're measuring, you think of the light as two sine waves, one from each arm, and we arrange the distances such that the two light waves cancel. So, the peak of one sits on the trough of the other, and in the ideal case, you would see no light, zero, right? And then if one arm is slightly different in light than the other arm, then they don't perfectly cancel, and now some light sort of trickles out.

• 37:17Neil deGrasse Tyson?

  Ooh, brilliant.

• 37:18Speaker 02

  Right, exactly.

• 37:19Neil deGrasse Tyson?

  They should get a Nobel Prize for that.

• 37:21Speaker 02

  They already did.

• 37:24Harrison Greenbaum?

  You're tied with Einstein.

• 37:28Neil deGrasse Tyson?

  So, it's always better to see a signal where there isn't otherwise a signal than to measure the difference between two large signals.

• 37:35Speaker 02

  Yeah, if you try to measure a tiny difference in a big number, it's really hard to measure. But you start with something that's very close to.

• 37:42Neil deGrasse Tyson?

  And error prone, too, yes, yes.

• 37:43Speaker 02

  You start with something that's very close to zero, and now you get anything, you got something.

• 37:47Neil deGrasse Tyson?

  Wow.

• 37:48Speaker 02

  So that's what we do.

• 37:50Neil deGrasse Tyson?

  And how strong is that extra signal compared with the amplitude of the waves to begin with? So what fraction of that amplitude is it?

• 37:56Speaker 02

  Yeah, so that's a sort of a technical detail because you start off with, you know, 100 watts of laser light. And by the time you-

• 38:07Neil deGrasse Tyson?

  That's a powerful laser.

• 38:07Speaker 02

  Yeah, that's a very powerful-

• 38:09Neil deGrasse Tyson?

  I believe it.

• 38:10Speaker 02

  Laser, particularly if it's a laser that's also, you know, as quiet, noise-free as ours.

• 38:17Neil deGrasse Tyson?

  What is my laser pointer?

• 38:19Speaker 02

  Your laser pointer is like a milliwatt.

• 38:21Neil deGrasse Tyson?

  Yeah. Oh, okay.

• 38:22Speaker 02

  A really bright one might be-

• 38:24Neil deGrasse Tyson?

  A few thousandths of a watt.

• 38:25Speaker 02

  Right.

• 38:26Neil deGrasse Tyson?

  Gotcha. And this is 100 watts.

• 38:27Speaker 02

  Yeah, so this is 100 watts at the laser and by the time the light has bounced between all the mirrors and so on, at any given instant in time, you could have, you know, hundreds of kilowatts of power circulating in the instrument. But at the time that we detected at the output, you know, we're trying to go for, you know, very little light, close to zero, we're measuring something around of order 10-ish milliwatts of light.

• 38:54Neil deGrasse Tyson?

  Okay. Relative to the hundreds of thousands of milliwatts that are moving around.

• 39:00Speaker 02

  That's right. The more interesting question is you can think about the output of the interferometer is itself just as, it has, it's a sinusoidal function. And so the way I like to think about it is we try to park ourselves at a trough.

• 39:15Neil deGrasse Tyson?

  In the bottom?

• 39:16Speaker 02

  At the bottom. And then we're asking, what is the smallest amount of light that you can distinguish, resolve? And that is how much of phase or distance path length you're resolving.

• 39:29Neil deGrasse Tyson?

  Mm-hmm.

• 39:29Speaker 02

  And so that's the number that corresponds to path length difference of 10 to the minus 18 meters.

• 39:37Neil deGrasse Tyson?

  Which is the fraction of the diameter of a proton that you were measuring.

• 39:41Speaker 02

  That's a thousandth the diameter of a proton.

• 39:42Neil deGrasse Tyson?

  Crazy talk.

• 39:43Speaker 02

  Yeah.

• 39:43Neil deGrasse Tyson?

  And so, so she slipped in a nice term in there, I want to like pull that out. She mentioned interferometer. Okay.

• 39:50Speaker 02

  Ooh.

• 39:51Neil deGrasse Tyson?

  That as a device.

• 39:55Neil deGrasse Tyson?

  Had to be invented. And it was invented at the turn of the century, the the previous century, by Mike Albert Michelson and Morley. What's his first name? I don't remember his first name. The famous Michelson-Morley experiment. They invented it to measure the speed of light. So the first truly accurate measurement of the speed of light was by Michelson and Morley using an interferometer where they had waves that either line up or they don't. And the amount that they don't line up will give you information about the speed of the light that they were measuring. So I mean, it's it's a hugely powerful. So they got the Nobel Prize for inventing that device.

• 40:36Harrison Greenbaum?

  It feels like they're just giving these things out. I think this is the third one we've heard about today. Just handing them out like candy.

• 40:44Neil deGrasse Tyson?

  So just I I'm I'm just impressed by how all this comes together.

• 40:48Speaker 02

  I think it's just a reminder to us that every discovery we make is built on everything that came before. Right? Because we we've talked about so many things that were invented 100 years ago that were important to the discoveries we made in 2015.

• 41:04Neil deGrasse Tyson?

  All right, so take us out with your prediction of what what discoveries await us to take the physics we now know into a new place? Or what new physics needs to arrive to take our understanding of the universe to a new place?

• 41:21Speaker 02

  Yeah, so I would say at the moment, the kinds of objects, astrophysical objects we've seen so far have been collisions of pairs of black holes or pairs of neutron stars, or maybe neutron stars and black holes in in the same binary system. And those were predicted. We kind of expected them, but even that has given us mysteries. Like, I'll give you an example. We've seen black holes that are around 100 solar masses. We don't know how nature forms those because if they're formed in the same way as black holes that are 20 or 30 solar masses are formed, stars don't do that.

• 42:01Neil deGrasse Tyson?

  Right, we don't that it means we don't understand how stars are born.

• 42:04Speaker 02

  That's right, or die.

• 42:05Neil deGrasse Tyson?

  Right.

• 42:06Speaker 02

  Right.

• 42:06Harrison Greenbaum?

  I always thought it's like you pick up an instrument and you practice a lot how how stars point.

• 42:13Neil deGrasse Tyson?

  Is that how that works?

• 42:13Harrison Greenbaum?

  I think there've been three films of that.

• 42:16Neil deGrasse Tyson?

  Yeah, they keep making the films. They keep remaking that one. How Star is Born. What I'm saying is, we've had three films to learn how a star is born. But let me just remind you that movie stars are called stars because we had stars first. Okay, we came first. Not because they're filled of gas.

• 42:32Neil deGrasse Tyson?

  Hot gas. They're named after objects in the universe, not vice versa, just to be clear.

• 42:38Speaker 02

  But Neil, I think this is a good idea for you. I think you need to make the ultimate Star is Born movie about real stars.

• 42:45Neil deGrasse Tyson?

  Oh, if we're gonna make the movie again, just make it right.

• 42:49Speaker 02

  Yeah, I agree.

• 42:51Neil deGrasse Tyson?

  I'll be the one in love with the star.

• 42:55Neil deGrasse Tyson?

  Well, thank you for enlightening us here with your insights and your expertise and your deanship.

• 43:04Speaker 02

  Oh, my gosh.

• 43:07Neil deGrasse Tyson?

  What I'd like to do is sort of take us out with a cosmic perspective, if I may. This is the part where I just talk to camera and you just pretend like you're paying attention.

• 43:18Neil deGrasse Tyson?

  Once again, we are exposed to major modern discoveries in science, physics in particular, that was enabled by creative thinking that preceded it, creative engineering, improvements in computational speed. These things happen, yeah, you can say, "I got a really fast computer," and you can be praised for that, but maybe someone can use that for something that they could not have solved before. "I have a new idea about how black holes work." Well, let others know about it because somebody could have another idea about how to apply

• 44:01Neil deGrasse Tyson?

  that to a discovery we're not even thinking about now. And so, this interconnectivity, this interdependence of cosmic discovery on these multiple frontiers is how science works. People ask, "Are we approaching the end of science?" Well, if you think everything that will ever be discovered has been discovered, then you probably think that. But my read of the history of this exercise tells me that...

• 44:35Neil deGrasse Tyson?

  If you think science is about to end, it's because you're not creative enough to imagine where else it could go. And look at all the dangling bits and pieces of all the scientific frontiers, and how they might one day come together with the next generation Einstein to take us into the next millennium of cosmic discovery. And that's a cosmic perspective. So, Inurges, thanks for coming back to StarTalk. We dovetailed another talk you were giving at NYU, sister institution downtown. Thanks for fitting us into your day. And again, it's ma vala vala. Yes, I did that correct.

• 45:16Speaker 02

  It is, it is. Thank you.

• 45:17Neil deGrasse Tyson?

  And Harrison, great to see you again. Same here. Good to hear about your show. Thank you. People can find you, Harrison Greenbaum. Dot com, at Harrison Comedy on social media. You got it. Neil deGrasse Tyson, your personal astrophysicist. As always, I bid you to keep looking up.