Deciphering Gravitational Waves, with Janna Levin

What is a gravitational wave? Janna Levin and comedian Matt Kirshen sit down with physicist Rainer Weiss to discuss LIGO, black holes, and the physics of gravitational waves.

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

• 0:01Neil deGrasse Tyson?

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

• 0:12Janna Levin?

  Welcome to StarTalk All-Stars. I'm Janna Levin, your All-Star host for the day. I'm an astrophysicist and author. Joining me as co-host is the funny Matt Kirshen, host of Probably Science. Hi, Matt.

• 0:27Matt Kirshen?

  How's it going?

• 0:28Janna Levin?

  Welcome back.

• 0:29Matt Kirshen?

  Thanks for having me back.

• 0:30Janna Levin?

  It's been like 10 minutes.

• 0:31Matt Kirshen?

  Yeah, it's nice to be here in space.

• 0:33Janna Levin?

  It's great to have you. And I also want to introduce one of my favorite people in the world. Joining us in the studio, Ray Weiss. Thank you, Jana. Otherwise known as Rainer Weiss, for long. Great to have you. Ray is Professor Emeritus from MIT. He is also one of the original architects of the LIGO detector, which announced the detection of gravitational waves last year. It was this year. Why does the prompt say "last year"? It happened last year. It happened last year. Sorry, guys. Now it's this year. It was one of the most groundbreaking discoveries of modern astrophysics and very personally important to me. Ray is one of the founders of the LIGO instrument and continues to work on the instrument all the time, as I know because I've been to the sites with you. You kindly let me perform.

• 1:18Janna Levin?

  You slog with me in the tunnel, I remember. Yes, in the heat of Louisiana. It was amazing. So it's so great to have you here. We're going to talk about LIGO, and gravitational waves, and black holes. So I think what we want to chat out is why this discovery was so important. I think that when people heard about it, it was so... the whole world stopped in February 11th, when the announcement was made. And for a minute, it was so exciting. Everybody was frozen. And then I felt like an hour later, people just weren't sure what it was all about. It's hard to understand.

• 1:49Matt Kirshen?

  I mean, I've got it covered because I'm obviously good on these things. But just for everyone else, if you could just kind of give a vague overview.

• 1:55Speaker 03

  Well, I'll try, but I was as mystified as you in the fact that it had this enormous public recognition.

• 2:02Janna Levin?

  Oh, yeah.

• 2:02Speaker 03

  I mean, you take other things.

• 2:03Janna Levin?

  Were you surprised?

• 2:04Speaker 03

  I was more than surprised. I was flabbergasted, to be honest with you.

• 2:07Janna Levin?

  Oh, really?

• 2:07Speaker 03

  I mean, my first real instinct that it had permeated the society was when I came to New York to come and visit you at the Pioneer Works. And I get in the subway, and there's this sign that says, you know, scientists can find gravitational waves, but you can't find an apartment in New York with an old walk-in closet.

• 2:26Janna Levin?

  Right.

• 2:26Speaker 03

  I said, where in the hell does that come from?

• 2:28Janna Levin?

  Exactly. It was a Jeopardy question.

• 2:30Speaker 03

  Is that what it was?

• 2:31Janna Levin?

  Yeah, no, also, as well.

• 2:33Speaker 03

  Oh, I didn't realize that. I didn't realize that.

• 2:35Matt Kirshen?

  Have you, has science now detected an apartment in New York with a walk-in closet?

• 2:39Speaker 03

  I haven't been looking lately. I don't live here.

• 2:41Janna Levin?

  If anyone can find it, Ray can. So, Ray, do you want to tell us what gravitational waves are? Because this is very hard for people to understand. They can say the words, but they really don't get what it's all about. And they certainly don't get why you played it to them as a sound.

• 2:55Speaker 03

  Well, let's start with what they might be, I mean, what they are. They're a result of Einstein's first thinking about how you measure things in space and time. In other words, he realized back in 1905 that the Newtonian theory we had, the theory that was, the theory that was, oh, we all learnt in high school, was inadequate. That you couldn't have things travel so fast that everybody knew about it instantaneously. There had to be some delay, because the fastest that things can move, even information, thought, is the velocity of light.

• 3:27Janna Levin?

  Right, so if the sun disappeared tomorrow, it should take us eight minutes.

• 3:30Speaker 03

  Well, that's right. If the sun disappears, well, yeah, it'll take about eight, nine minutes before we really know about it.

• 3:36Matt Kirshen?

  Which is great if you're like a magician or something.

• 3:38Janna Levin?

  Do you need the extra time?

• 3:39Matt Kirshen?

  Well, yeah, because David Copperfield made the Statue of Liberty disappear, but he had like seconds, really, to do that in.

• 3:45Janna Levin?

  If you had eight minutes to play with, anything.

• 3:48Matt Kirshen?

  You could be an amateur magician, still, kind of like, you have time to get some helpers to actually shove it out of place.

• 3:53Janna Levin?

  What'd you do with the sun, Matt?

• 3:54Speaker 03

  Yeah, but those eight minutes are damned important.

• 3:56Matt Kirshen?

  Right.

• 3:56Speaker 03

  Because they tell you that there has to be some mechanism for information to travel not infinitely quickly.

• 4:03Janna Levin?

  Right, so in Newton's theory, it would happen instantaneously.

• 4:05Speaker 03

  That's the first-order way of talking about gravitational waves. And specifically, what are they? Einstein had a different way of looking at gravity than Newton did. And he taught us all that space and time get distorted by gravity. You get curvatures, you get distortions of space and time. And what a gravitational wave is, is a traveling distortion of space and time, but we measure it as a distortion in space. And the very special thing, so you don't have, you can imagine what it is, it's not very hard to imagine, is that it's a stretching of space and a compression of space. And here's, just bear with me, here's what it is. Where the wave travels, let's say, toward you, and it does its dirty work perpendicular to the direction in which it's moving. So something's doing this.

• 4:45Janna Levin?

  Mm-hmm.

• 4:46Speaker 03

  And while it's doing this in one dimension-

• 4:47Janna Levin?

  Okay, Ray's oscillating his hands in and out.

• 4:49Speaker 03

  Oh, yeah, I gotta tell you, that's right. Waving my hands back and forth.

• 4:52Matt Kirshen?

  It's almost like a slinky spring.

• 4:53Speaker 03

  That's well, a slinky, let's say, a slinky in the x direction, but a slinky inverted in the y direction, it's doing the opposite.

• 4:59Janna Levin?

  I hope you all use right-handed coordinate systems.

• 5:01Speaker 03

  In one dimension, in the direction it's moving, perpendicular direction it's moving, it's stretching in one dimension, it's compressing in the other. And that continual compression, expansion, travels at the velocity of light toward you. And that's the way to imagine a gravitational wave.

• 5:14Janna Levin?

  Now, when you first started thinking about this,

• 5:16Speaker 03

  Yeah.

• 5:17Janna Levin?

  you were a young professor at MIT, and you had this whole gravity research program. And I know you confessed to me that they asked you to teach a class in general relativity.

• 5:26Speaker 03

  Well, I'll confess again. What Jana's referring to is a very big embarrassment. See, I come to MIT having been to Princeton, the hotbed of general relativity and gravity, and I come and I start a group, very expendable, I'm an experimenter. I'm not a theorist, like Jana. Jana's a true theorist. But I'm an experimenter, I deal with things with my hands and, and what happened-

• 5:47Matt Kirshen?

  You already, like, before the show even started-

• 5:49Janna Levin?

  He was using his hands wildly.

• 5:50Matt Kirshen?

  Well, yeah, before the show started, you were kind of looking at the microphone and like taking it apart, like you can't help yourself.

• 5:55Janna Levin?

  No, you can't.

• 5:57Speaker 03

  Yeah, you gotta do that, you gotta find out what you're, what you're surrounded by, come on, it's part of the world.

• 6:01Janna Levin?

  Palpate, palpate the world.

• 6:02Speaker 03

  So, you know, it's tactile and it's all sort of seeing things. But anyway, so as Jana says, that what happened is that I'm running this group that is supposedly about very complicated topics like cosmology, which is the history of the universe, and also gravitation. Okay, those were the two things I started. And then the department head comes to me and says, you know, "We would like you to teach a course in general relativity", which is a course of the new kind of gravity. And I couldn't tell him, I didn't know a damn thing about it. I mean, I really didn't know much about it. I didn't know the mathematics. I mean, the students, when I finally started teaching, were probably barely, I was barely half a day ahead of the students, if at all.

• 6:41Matt Kirshen?

  Right.

• 6:42Speaker 03

  So here I go, and they asked me a very hard question as we go along. The course has its ups and downs, as you can well imagine, and they asked me a hard question. They said, "Look, what is a gravitational wave?" And I tried to answer it, but what was going on at that time was that Joe Weber, who was a physicist at the University of Maryland, had begun to talk about that he might have discovered gravitational waves.

• 7:03Janna Levin?

  Mm-hmm, and this would have, his campaign started in the 50s to...

• 7:06Speaker 03

  No, this was started in the 60s.

• 7:08Janna Levin?

  Sixties to late 60s.

• 7:09Speaker 03

  Well, he started really quite early, in 62, and he made the announcement that he had discovered gravitational waves in 1969. That caused a tremendous furore.

• 7:18Janna Levin?

  He was incredibly famous.

• 7:19Speaker 03

  Well, yeah.

• 7:20Matt Kirshen?

  And he was lying? He was just...

• 7:21Speaker 03

  No, no, no, don't say lying. That's not the right word.

• 7:24Janna Levin?

  We're all very defensive about Joe now.

• 7:25Matt Kirshen?

  I don't want to brag, but I also did discover gravitational waves, like about a month before you guys.

• 7:30Speaker 03

  That's good, I'm glad of that. What did yours look like?

• 7:34Matt Kirshen?

  It was just like, I just put a cup on a, it kind of wobbled a bit.

• 7:37Janna Levin?

  And the water wobbled, and he knew that they were gravitational waves.

• 7:40Matt Kirshen?

  Jurassic Park.

• 7:42Speaker 03

  Well, like those two birds in the New Yorker cartoon. Probably saw that cartoon.

• 7:45Janna Levin?

  I didn't see it.

• 7:46Speaker 03

  Two birds sitting, this is right after the discovery, again. Two birds sitting on a branch. It was on the 12th of February. We announced on the 11th of February. So somebody had prior information.

• 7:55Janna Levin?

  Right.

• 7:56Speaker 03

  But these two birds, two birds are looking, one looking at the other, and the one says, "Hey, did I hear you, or was that a gravitational wave?" And that could have already, that's the kind of thing. Anyway, so let me get back to the story. The thing was that, they asked me about this, and I frankly, be honest with you, despite having trouble with the mathematics, I also had trouble with understanding Weber's experiment. It's not that he was lying or anything like that, it's just a way, too complicated for me to understand exactly what he was doing. So I spent a lot of time one night, thinking about how could I explain what a gravitational wave does, and how would you detect it in the most pristine, simple-minded way possible. And that's where this haiku, as you call it, came about. Which is the, I thought, well, you know, one way to do it is send some masses out there,

• 8:40Speaker 03

  put them out in outer space, put clocks on them, two clocks, one on one, clock on the other, and have a light beam go from one to the other and measure the time. That's all.

• 8:48Janna Levin?

  Yeah.

• 8:48Speaker 03

  Very straightforward measurement.

• 8:50Janna Levin?

  And they'd have to be sort of floating, so that when-

• 8:52Speaker 03

  Floating out there.

• 8:52Janna Levin?

  Like bobbing on the wave of the ocean, if something floats in the ocean.

• 8:56Speaker 03

  Well, they're actually just moving along without any forces on them. And then, all of a sudden, a gravitational wave comes along and it changes the time that light takes that goes between them. That's it.

• 9:06Janna Levin?

  Mm-hmm.

• 9:06Speaker 03

  Makes it shorter for a while and longer, does exactly what the gravitational-

• 9:09Janna Levin?

  But you started to build one.

• 9:10Speaker 03

  Well, yeah, yeah, yeah, but that's the basic idea. And by the way, that idea is the one that propagated into the later on LIGO and everything else.

• 9:17Janna Levin?

  Is this what you wrote about in your book? Is this what? Yeah, yeah, so I was fascinated with, you mentioned Ray looking at the microphones and all this stuff. I was fascinated that Ray said that he started life with one ambition, which was to make music easier to hear.

• 9:30Speaker 03

  That's right.

• 9:30Janna Levin?

  And then you dreamt up, which is basically a cosmic recording device, sort of insane gigantic cosmic recording device to record sounds from space.

• 9:39Speaker 03

  She was the only one in my whole life who ever made that analogy, and she was right. You know, I mean, I told her the story.

• 9:45Janna Levin?

  Awesome.

• 9:45Speaker 03

  Because I think you have a musical background, or around you is music, and understood this right away.

• 9:50Janna Levin?

  Yeah.

• 9:51Speaker 03

  It's absolutely true. It was-

• 9:52Janna Levin?

  Yeah, so- What's the book called? Black Hole Blues and Other Songs From Outer Space. Which, if I was Neil deGrasse Tyson, I would say in an awesome, deep DJ voice. I think I do have him recorded saying it. I should hear it. You just play that in at that point? Right, exactly. Just write, edit that in. But, so you, this is, okay, early 70s now we're talking about. Okay, so it's 50 years ago. And you started to build the first machine, but it was really quite small. And as I remember, you got a lot of flak for it because nobody thought you were going to succeed. They thought you were wasting your time.

• 10:27Speaker 03

  There was worse than that. This is sort of an interesting epic in the whole history of the field. Yes, I got some money from the military, by the way. It was funding my research. At the one time, military support was very, very good. You know, it was not had no had no onus associated with it in the society. And what happened was that they supported this. And what happened, I got about fifty thousand dollars to build a small prototype. And then, all of a sudden, everybody got very disenchanted with the military when the Vietnam War happened. And the funding for this.

• 10:58Janna Levin?

  There goes your funding.

• 10:59Speaker 03

  Funding stopped because the military was only supposed to support those things that were relevant to its mission. And gravitational waves weren't quite in the military's complement of things they had to worry about.

• 11:09Matt Kirshen?

  Right.

• 11:10Speaker 03

  So, and.

• 11:11Matt Kirshen?

  How can we use gravitational waves to kill our enemy? Like, how can we?

• 11:15Speaker 03

  Well, I'll tell if it gets there, I'll tell you later.

• 11:17Janna Levin?

  We'll do that in segment three.

• 11:18Speaker 03

  If you care to pursue it, if you want to pursue this, I'll tell you later.

• 11:20Matt Kirshen?

  Or at least just to like upset someone, like, how can I use it to upset a neighbor? Like, my neighbor's playing music too loud.

• 11:25Janna Levin?

  I'm gonna send gravitational waves towards them full blast.

• 11:29Matt Kirshen?

  You're now the master of gravity, right? That's what we're dealing with here?

• 11:32Janna Levin?

  Well, we're gonna come back. We're gonna come back to this discussion. And but before then, I think it's time for us to take some cosmic queries. So if you are out there in the ether.

• 11:41Matt Kirshen?

  All right.

• 11:41Janna Levin?

  Send us your messages. It's too late now, of course.

• 11:44Matt Kirshen?

  It is too late. Well, is it?

• 11:46Janna Levin?

  I don't know. It depends if we can time travel. Can gravitational waves help us time travel?

• 11:50Matt Kirshen?

  You know, might as well ask this question then. This is perfect unintentional timing here. But Jake the Guy on Instagram is asking, does any of this mean I can travel in time?

• 12:02Janna Levin?

  Ray, do gravitational waves help us travel in time?

• 12:06Speaker 03

  I don't know how they would, but maybe you have an idea. You're a theorist.

• 12:09Janna Levin?

  I don't think so. I don't think so. I can't think of a way in which they would help us travel in time. But, you know, you can always travel to the future. I mean, always, if you set things up.

• 12:20Matt Kirshen?

  That's a cop out, though.

• 12:21Janna Levin?

  I can travel towards your future, though. That's pretty weird. I could travel to a time when you are fifteen years older and I'm only like a couple of months older.

• 12:29Matt Kirshen?

  Okay, by going off to space and coming back?

• 12:31Janna Levin?

  Yeah, I can, you know, send you far from the earth, or I can go to a black hole or something like that. So I can always travel to somebody else's future. But traveling to the past is the hard part. That's pretty tricky.

• 12:42Matt Kirshen?

  All right, Taylor from Eugene, Oregon.

• 12:45Speaker 03

  We did a fairly lousy job of answering him. You know, it was a good enough.

• 12:48Janna Levin?

  Yeah. I think I'm pretty sure Ray just said, I gave a lousy answer.

• 12:53Speaker 03

  You did give a lousy answer.

• 12:54Janna Levin?

  And there's only one person in the world I would take that rather.

• 12:58Speaker 03

  Probably want something very deep.

• 13:00Janna Levin?

  It was, it was deep, you just weren't paying enough attention.

• 13:04Matt Kirshen?

  So, Taylor from Eugene, Oregon, asks, "Do gravitational waves have any direct effect on the physical environment? For example, if an event causing gravitational waves occurred close enough to Earth, would it have any discernible effect on humans or the planet?"

• 13:19Speaker 03

  Well, that's a question I can even answer. And in fact, if we measured this event from two black holes, and I have to start that way, which was, fortunately for us, 1.2 billion light-years away. But had we been, let's say, within a few tens of years of that, we would have measured something. And you would have measured exactly what we measure in our detectors. You wouldn't stretched in one dimension, then compressed in the other dimension, you would have felt that.

• 13:48Janna Levin?

  Now, we resist stretching and compression, but our, you know, auditory mechanism is designed to resonate in response. Do you think that we could technically hear a gravitational wave, even in the absence of air?

• 14:01Speaker 03

  I don't think that's, that's not because...

• 14:02Janna Levin?

  I've been saying this for months.

• 14:03Speaker 03

  Well, I don't think it's true. Well, I think, let me, let's get to that, this issue right away, because we've, we, not you, we have generated some confusion by saying this is listening to the universe, which is what a lot of people have said about this. And it's true, but it's nothing, it's not necessarily a sound wave that's exciting us, you see? And what is happening is that we are seeing these stretchings and compressions, and that's certainly going on in your ear, too. The compression and extension, even for that one mile, one, one year away, light year away, is still too small for your ear.

• 14:36Janna Levin?

  Right, so how close do you, oh yeah, I would agree with that.

• 14:37Speaker 03

  If you got close enough, you would feel it, you would feel it over your whole body, and you might hear something. But that's not what we're doing.

• 14:43Matt Kirshen?

  So, like, a sound wave is like the compression and expansion of the air around you?

• 14:47Speaker 03

  That's right.

• 14:48Matt Kirshen?

  And this is, actual space itself is doing that?

• 14:50Speaker 03

  Yeah, but, but be careful. What it is, is space, you're right, space is doing the expansion and the compression. On the other hand, our instruments, this is where it gets converted into sound, that's why I looked at your microphone, is that what we do is, we have a device that measures these very tiny displacements, we're using light and the timing of light, but then we convert that into a sound by amplifying it. And then that gets put into a loudspeaker, yes, and then it makes a sound.

• 15:13Janna Levin?

  It's a lot like an electric guitar.

• 15:15Speaker 03

  Exactly, but exactly like an electric guitar. You've got a very good analogy. Very good analogy. And the other thing is that it's an, the other, the other piece of it is that this phenomena, these phenomenas we're seeing, phenomena we're seeing, are things that have the frequency of our auditory system. That's the nature is making things with frequencies that run from the bottom of the piano to the top of the piano.

• 15:39Matt Kirshen?

  I mean, that's just by chance?

• 15:40Speaker 03

  Well, that's because the things we're looking at, well, it's a little more than that. What it is, is our instrument's only sensitive in that band, okay? And on top of that, nature's kind enough to give us something that does its wiggling and expanding and contracting and accelerating in that frequency band.

• 15:54Janna Levin?

  A couple of black holes collide, they happen to ring spacetime in the human auditory frequency.

• 15:58Speaker 03

  Yeah, okay, so it's not sound waves traveling through space. I just don't want to have that.

• 16:02Janna Levin?

  It's like an electric guitar string. It's not a sound wave traveling through space. But you had to build LIGO to build the body of the guitar.

• 16:08Speaker 03

  That's the guitar.

• 16:09Janna Levin?

  To record the shape of the wave.

• 16:10Speaker 03

  Absolutely. That's a beautiful analogy.

• 16:12Janna Levin?

  Excellent, and then we're gonna all break out into air style guitar. Give us another cosmic query.

• 16:17Matt Kirshen?

  From Florida, Sarah Garvijanser is asking, "When gravitational waves are recorded, is there a way to know which black holes collided to make them? And is there any other event out there that could cause gravitational waves? If so, how would they differ?"

• 16:31Speaker 03

  Boy, that's a profound question. And this has a lot of different pieces to it, that question. Let's first of all say, how do we know that we are even seeing black holes? Is that, I think that's one way, in our experiment, that we were seeing black holes. You have to do an analysis to find that out. It could be other systems that, you know, neutron stars, there are many, many things that oscillate and wiggle that can make gravitational waves. But it happens to be, and this is the important thing, the specific wiggles we saw, when you solve them, as trying to figure out what the motions are, that made those wiggles. You wind up with masses that are, in our case, the first one was too big. The masses are thirty, each one of the masses was about thirty solar masses.

• 17:11Speaker 03

  And we don't know of things, we know of ordinary stars that do that, but they're too big. Because what happens if you take an ordinary star?

• 17:18Janna Levin?

  It was surprising how big they were.

• 17:20Speaker 03

  They what?

• 17:20Janna Levin?

  It was surprising how big they were.

• 17:22Speaker 03

  Yeah, monstrous.

• 17:23Janna Levin?

  It's exciting.

• 17:24Speaker 03

  I mean, all the black holes people had seen, or, not, nobody's seen a black hole, but had evidence for, was around ten solar, and smaller, around there. No, the important thing is that, once you make the calculation that you know it's about thirty solar masses that are jiggling around, you then say, "My god, look how close they are," but from the equations, you can say, "They're much closer than any star, they would be inside of each other."

• 17:43Janna Levin?

  Yeah, they're a couple hundred kilometers across.

• 17:45Speaker 03

  These things are no bigger than the, just the size of Connecticut, maybe.

• 17:48Janna Levin?

  Yeah.

• 17:48Speaker 03

  You know, and, or even smaller, maybe.

• 17:50Matt Kirshen?

  The only thing's that big that can also be that close are black holes.

• 17:53Speaker 03

  Well, that's, that's the argument. That's fundamentally the argument.

• 17:56Janna Levin?

  That's the best we can do.

• 17:56Speaker 03

  Exactly the argument.

• 17:57Janna Levin?

  So maybe there's something else, that when we got close, we realized didn't have an event horizon, wasn't a complete shadow, wasn't really empty spacetime, that, you know, it can be different than what we think of a black hole as, but it's gotta be heavy and small.

• 18:21Speaker 04

  I'm Jasmine Wilson, and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 18:38Janna Levin?

  When you were talking about, in the last segment, running out of funding, because the military funding was cut, and you told me the next big event is I Met Kip. I loved that line.

• 18:50Speaker 03

  I'll tell you what the next event was. The next event was really trying to get money. That was the next event, to try to finish it. And that's what happened. Kip comes soon.

• 18:58Janna Levin?

  Mm-hmm.

• 18:59Speaker 03

  But the next event was really trying to get some money, and that's where I ran into the trouble.

• 19:02Janna Levin?

  Mm-hmm.

• 19:03Speaker 03

  Said there were trouble getting that money, getting that. The people were skeptical.

• 19:06Janna Levin?

  And your instrument was a meter and a half.

• 19:08Speaker 03

  Yeah, the initial prototype, it was a meter and a half. If we wanted to just demonstrate. It was never intended to make a detection.

• 19:15Janna Levin?

  Mm-hmm.

• 19:16Speaker 03

  In fact, nothing until LIGO was even ever able to contemplate making a detection.

• 19:19Janna Levin?

  Didn't somebody tell you I could do better by looking out the window? If the sun blew up, you couldn't detect it?

• 19:24Speaker 03

  Yeah. Well, one of my graduate students, the first time I ever put a graduate student on the project, had a terrible time with his, with my colleagues because they had no measurement of a real scientific result. They had a beautiful piece of technology, but that's not what you get a PhD for in physics, necessarily. But let's get away from that, because you asked the question. So what happened is they, the, um, I tried to get money and I didn't. And what happened is the National Science Foundation, which is what they do always, sends proposals to everybody who knows something about this. And what they did is they sent it to Europe.

• 19:55Janna Levin?

  Mm-hmm.

• 19:55Speaker 03

  And the Europeans don't have quite the same mores about an American proposal. And I had a very interesting conversation with a guy from the Max Planck Institute.

• 20:03Janna Levin?

  This is after your grant was declined.

• 20:05Speaker 03

  Yes. Well, yeah, that's right.

• 20:06Janna Levin?

  Yeah, it was declined. So here you are with no money.

• 20:08Speaker 03

  Yeah, yeah, here I am. In 1975 or so, we had started building the thing in 72.

• 20:12Janna Levin?

  Yeah.

• 20:13Speaker 03

  And I was trying to finish it. And so we got this wonderful call from a guy at the Max Planck. And he says, "You know, we've been working on Weber bars. We didn't see anything." And by the way, they had done a beautiful job of not seeing anything.

• 20:24Janna Levin?

  Right.

• 20:25Speaker 03

  Sometimes not seeing something is better than seeing something, especially if it's not there.

• 20:29Janna Levin?

  In that case, yeah.

• 20:31Matt Kirshen?

  I like to be talking about my dancing.

• 20:35Matt Kirshen?

  I think it's better to not see. It's better to not see. Every scientist will tell you that.

• 20:41Speaker 03

  So, because you make confusion if you see something that's there and that's not supposed to be there. And so, uh...

• 20:45Matt Kirshen?

  There are a lot of things there that are not supposed to be there.

• 20:47Speaker 03

  Yeah, yeah. And so what happened is, very good. So what they did is they asked me if they would mind if they would work on this. They thought it was a good idea. I said, "How can you mind?"

• 20:57Janna Levin?

  Mm-hmm.

• 20:58Speaker 03

  And they asked me if I had a graduate student. I could send them, or somebody that had been working on this.

• 21:02Janna Levin?

  Here they are. They're kind of pulling ahead on your idea.

• 21:05Speaker 03

  They pulled way ahead.

• 21:06Janna Levin?

  They pulled ahead on your idea. They had funding.

• 21:08Speaker 03

  They had funding and they were very good. Besides, give them credit. They were superb.

• 21:12Janna Levin?

  Right.

• 21:12Speaker 03

  And that also started, my colleague...

• 21:16Speaker 03

  The Ron Drever in Scotland, who also was doing Weber bars of a different kind, and then he got interested in this.

• 21:23Janna Levin?

  Mm-hmm.

• 21:24Speaker 03

  And both of those groups, I just have to say it and make sure people hear it.

• 21:26Janna Levin?

  Mm-hmm.

• 21:27Speaker 03

  They both.

• 21:28Janna Levin?

  Yeah.

• 21:29Speaker 03

  Did a spectacular job of making the thing better, the idea better, and getting the thing working.

• 21:33Janna Levin?

  Now, eventually.

• 21:34Speaker 03

  So that's, after that is when I met Kip.

• 21:36Janna Levin?

  Right, so eventually it becomes you, Kip, and this is now fast-forwarding 10 years, you, Kip, and Ron Drever become the three, the troika.

• 21:46Speaker 03

  That's right.

• 21:47Janna Levin?

  That initiate the development of LIGO. It even gets a name, it finally gets a name in like 1985. It didn't have the name before. Laser Interferometer Gravitational Wave Observatory.

• 21:55Matt Kirshen?

  So LIGO started 30 years ago.

• 21:57Speaker 03

  It started, well, LIGO started really, now it's a little earlier than that, in 83.

• 22:01Matt Kirshen?

  Okay.

• 22:02Speaker 03

  Because what happened is we did a study, this is that Kip getting the Kip.

• 22:05Janna Levin?

  Mm-hmm.

• 22:05Speaker 03

  Has a little prelude to it, yeah.

• 22:07Janna Levin?

  Mm-hmm.

• 22:08Speaker 03

  If we, I couldn't get the money for the prototype, eventually I got some money. But I decided by looking at the wonderful work that had been done in Europe, that I was not going to be in such a hurry to finish the prototype, but rather, I would rather do a study to find out what it really would take to build a LIGO.

• 22:23Janna Levin?

  Right, so here you had a 1.5-meter machine, and how big did you decide it had to be?

• 22:27Speaker 03

  It had to be, well, we started studying, and I did a whole study of it, it looked like it had to be over a kilometer.

• 22:31Janna Levin?

  Right.

• 22:32Speaker 03

  And I thought, I want to do 10 kilometers.

• 22:34Janna Levin?

  Thousand-fold.

• 22:34Speaker 03

  Yeah, well, I want to do 10 kilometers.

• 22:35Matt Kirshen?

  You had like something that was about like, yay, boo.

• 22:37Speaker 03

  Yeah, that's right.

• 22:38Janna Levin?

  Yeah, arm span to it doesn't fit on the MIT campus or even in Cambridge, Massachusetts anymore.

• 22:44Matt Kirshen?

  Right. Most of my experiments, like the size of a matchbox.

• 22:47Janna Levin?

  Right. They involve.

• 22:48Speaker 03

  Nowadays, they even get smaller, you know, these nanotechnology things, but you can't do gravitational waves for that way. Why? You can't do it because the amount of motion is bigger, the amount of motion the gravitational wave induces is proportional to the size of the system. See, what's constant in a gravitational wave is the strain, that's getting a little technical.

• 23:06Janna Levin?

  Mm-hmm.

• 23:06Speaker 03

  That's the ratio of the added displacement, the compression or expansion of the gravitational wave, divided by the distance that the object's already apart. And that hot, that number, that ratio is a constant.

• 23:17Janna Levin?

  Yeah, it's very small. So LIGO now has these mirrors suspended at the corners of this L-shaped, four kilometer long, two instruments on two different coasts, one in Louisiana, one in Hanford. By how much are the mirrors displaced? You're describing that that's the same, so for four kilometers.

• 23:33Speaker 03

  Do you mind if I use the exponential notation? I have to.

• 23:34Janna Levin?

  I can translate.

• 23:35Speaker 03

  You can translate. Well, it's 10 to the minus 18 meters.

• 23:38Janna Levin?

  Which is a million trillion.

• 23:40Speaker 03

  Okay. You like that? Fine.

• 23:42Janna Levin?

  A millionth of a trillionth of the size of the arm. So over four kilometers, it's very small. Which is how, it's like a...

• 23:51Speaker 03

  It's 10 to the minus 21 is the strain, and it's 10 to the minus 18 is the amount of motion in a four-kilometer arm.

• 23:57Janna Levin?

  Ah, right. So that comes to about a 10,000th of the width of a proton.

• 24:01Speaker 03

  Exactly. That's exactly right.

• 24:03Matt Kirshen?

  And you had to convince who to let you build this?

• 24:05Speaker 03

  Well, a lot of people. And that was the thing you see. When you tell, you tell somebody you're going to measure, tell an engineer, I mean, a solid, well-rounded engineer, that you're going to measure something at 10 to the minus 21, which is really the right number to use, because that's what the gravitational field strength is. They look at you like you were sort of a madman. And, you know, I mean, nothing gets measured at that, 10 to the minus 21. So that's the first problem you have. The second problem you have is you've got a nut like me, trying to convince some heavy that, you know, you can do this.

• 24:33Matt Kirshen?

  Right.

• 24:34Speaker 03

  Now, why should they trust me? You know? That's the other problem. I have no reputation for that.

• 24:38Janna Levin?

  Well, plus, people weren't even sure there were black holes out there for a large part of your initiative.

• 24:43Speaker 03

  And you, and what Jana just hit is the fundamental problem, that really the fundamental problem that we had, which was, nobody could tell us how much, how, what were the sources. So now we have three, a triple go. That's really bad. A triple no, let's put it that way. An insanely small number, a guy who's a little bit of a flake, okay, driving it.

• 25:02Janna Levin?

  That would be you?

• 25:04Speaker 03

  Yes, I'm afraid so. And then, nobody can attest that there's real sources. And people at MIT, where I was a, where I was a faculty, saying black holes didn't exist. See, that was a whole backdrop of this as well.

• 25:17Janna Levin?

  So what possessed you to keep going?

• 25:19Matt Kirshen?

  You're trying to persuade them to spend money to detect the effects of something that they don't think exists.

• 25:23Speaker 03

  That's right. And it's a lot of money, 100 million bucks about.

• 25:26Janna Levin?

  Well, Ray, you didn't know that they existed either. I mean, you didn't know. So what possessed you to keep going? I mean, it is insane.

• 25:34Speaker 03

  Well, I'm going to give you a very silly, silly answer, which is the truth.

• 25:38Janna Levin?

  Okay.

• 25:39Speaker 03

  A really silly answer. You think I'm a really profound scientist. That's baloney. Well, I enjoyed the work. And I enjoyed the people. And that was what drove it. I hate to tell you that. It was interesting work to do.

• 25:53Janna Levin?

  I think that's a great thing for people to understand. Scientists do what they do because they love it, not necessarily out of ego satisfaction.

• 26:00Speaker 03

  No, the end result was, it was an interesting result. Could we get such a result? It was a good gamble to take. But that wasn't the thing that drove me, I have to tell you that.

• 26:07Matt Kirshen?

  It is something that I get, because like, when I'm doing my experiments on the effects of paint drinking on blindness. Like, it's not, it's not the glory, I'm not going for the glory. It's actually, it's just about the work and it's fun, I enjoy it.

• 26:19Janna Levin?

  And you fully expect, though, that there will be glory at the end of the day.

• 26:22Matt Kirshen?

  Yeah, I expect that there might, there's a bit of me in the back of my mind that's like, yeah, it is gonna cause blindness.

• 26:27Janna Levin?

  You're gonna be the name of a paint color.

• 26:29Matt Kirshen?

  I will be able to write it up. But, at the time, you just do it. You just drink that paint and you write down your results as best you're able to write.

• 26:36Speaker 03

  So now we get to Kip, because, see, Kip was a different kind of person. Kip was a theorist, okay? And he had spent a lot of his life thinking about what might be the sources of gravitational waves. And in fact, he started writing some very elegant stuff already in the seventies, early seventies, about if there were a way to measure gravitational waves, what would be interesting to detect? And he started inventing a lot of very interesting ideas.

• 27:03Janna Levin?

  So Kip really pushed the science case. And you know, he was so cool-headed, he was just totally unflappable, in the sense that even when other people were saying, "We won't detect black holes, we won't detect black holes until 2020," some people told me. As recently as August, right? And Kip was like, "Nope, black holes first, black holes are gonna be first." So he, he really pushed that scientific case.

• 27:23Speaker 03

  Well, and he had a, and he had good reason, because you see, he had developed a very, probably one of the most prestigious groups in the country for the theoretical parts of gravitation. He, it's interesting, Kip and I, we didn't know, well, Kip tells me he thinks he remembers, but I don't. We were both at Princeton together at the same time. I was a postdoc, he was a grad student. And by the way, Joe Weber was there also, exactly the same time.

• 27:47Janna Levin?

  With John Wheeler.

• 27:48Speaker 03

  John Wheeler, exactly.

• 27:48Janna Levin?

  The American granddaddy of American relativists, yeah.

• 27:53Speaker 03

  So Kip was, the reason, I think, what's so important for Kip to be part of it, is he gave it a... A certain cache, I mean, the fact is, he showed people that it was possible that you could have sources besides the one that anybody, everybody knew about.

• 28:08Janna Levin?

  Supernova?

• 28:09Speaker 03

  Which was a supernova.

• 28:10Janna Levin?

  So when a star explodes, it can wobble spacetime, which we now think is probably the hardest thing to go for.

• 28:16Speaker 03

  It's a stinker.

• 28:17Janna Levin?

  Yeah.

• 28:18Speaker 03

  Very hard sources.

• 28:19Janna Levin?

  So, before we get to the discussion of the actual discovery, let's take some cosmic queries.

• 28:24Matt Kirshen?

  All right, so Gabriel Thielen, who's a Patreon patron, says-

• 28:28Speaker 03

  What kind of Patreon?

• 28:29Matt Kirshen?

  Patreon. It's a website that lets people give money.

• 28:32Janna Levin?

  They're supporters of the fabulous show.

• 28:34Matt Kirshen?

  Financial supporter of the show. And Gabriel asks, theoretically, is there anything stopping gravitational waves from traveling faster than the speed of light? It is the same phenomenon, is it not, as a theoretically, a theoretical localized artificial spacetime distortion or warp? Thank you very much.

• 28:53Janna Levin?

  Can I try this one? And then Ray, you jump in. So, just like there are light waves, electromagnetic waves, which is radiation, there is a particle complement to that, and that is a massless particle, and it travels at the speed of light. We think that that's exactly analogous to what's happening with gravitational waves, that there's a wave in the gravitational field, and that there is a particle called the graviton, which is massless in Einstein's theory. That might be wrong, but in Einstein's theory, it's massless. And in that case, like all massless things, it travels at the speed of light. No faster, no slower. But that could be wrong. It's very hard to test the speed of light by looking at gravitational waves. I'm sorry, the speed of the gravitational waves.

• 29:38Janna Levin?

  It's very hard to test, isn't it?

• 29:39Speaker 03

  Well, we try to make an attempt. Would you want to hear about that?

• 29:42Janna Levin?

  Yeah.

• 29:43Speaker 03

  I mean, if we ever get, I mean, there's a future and there's a current. I'll give you the future because it's easier to understand. Now that we are in the business finally of detecting things, people will try to look for not just bursts of gravitational waves, but rather ones that are very steady radiators, like, you know, an antenna on a transmitter blowing its waves out into space.

• 30:02Janna Levin?

  Like a neutron star with a bump on it.

• 30:04Speaker 03

  A neutron star with a bump on it that's rotating. And so it gives a nice continuous wave.

• 30:09Janna Levin?

  Like a monotone.

• 30:10Speaker 03

  Yeah, exactly. Well, it's slowly decaying, but that's, it's a monotone. You're absolutely right.

• 30:14Janna Levin?

  Over our time scale.

• 30:15Speaker 03

  And then what happens is a very interesting thing. You can do a very simple thing that even I can imagine. You can look at that source as we move around in our orbit in the solar system, and you will get, at a time, each time, you know, this source will be someplace in the orbit, outside of our orbit, and we go around, and it takes different lengths of time for the signal to get to us. And since we know our velocity, we can get the velocity of light, because we increased the distance to the object. We know how much we increased it by. So it's a very straightforward kinematic measurement. On the other hand, we already have sort of a quasi-measurement of the velocity of gravitational waves from a simple thing. We saw, I have to explain, as Jenna said, we have two of these detectors. One in Louisiana, another one in Washington State.

• 30:59Speaker 03

  And we saw the signal first, in Louisiana. And seven milliseconds later, we saw it in Hanford, Washington. That already tells you it's moving pretty damn close to the velocity of light.

• 31:10Janna Levin?

  Yeah, as it crosses the continent.

• 31:11Speaker 03

  As it crosses the continent. That's a pretty good way of...

• 31:13Janna Levin?

  It's pretty great. It's a, I love that the seven milliseconds are just clocked. It's fantastic.

• 31:19Matt Kirshen?

  So Nathan Kruger on Facebook says, "Are there currently any plans to conduct the double slit experiment using gravity waves?"

• 31:25Speaker 03

  Ah, that's an interesting question.

• 31:27Janna Levin?

  It's so, gravity is so weak, it's so hard to manipulate. Ray, what do you think?

• 31:33Speaker 03

  I'll tell you what the real problem is. Uh, two problems. One of those, you can't make us, you would have to make an artificial source to do that. And when you start doing that, you'll find out that you just don't have the power. You don't, you can't accelerate enough mass and move it fast enough so that you can even detect the waves.

• 31:50Janna Levin?

  Yeah.

• 31:50Speaker 03

  And Einstein said this in his very first paper on gravitational waves in 1916. He writes a lovely sentence at the end of the paper, saying, "Look..." He points to all the calculations, he says, "No, it's very unlikely," in fact, he doesn't even say unlikely, "it's impossible that these waves will have any physical consequence that we can measure." Because of that, that he tried to look at things like stars, what he knew about, or locomotives smashing into each other. I'm making that up because I don't know what he really thought about it. I mean, that piece of paper that says that's where he did his calculation.

• 32:19Janna Levin?

  Yeah, he didn't believe black holes were real, so...

• 32:21Speaker 03

  Well, the other thing is, black holes are not even going to be considered at that moment. But just the calculation where he came so pessimistic about this. I'd like to have to see a piece of paper that has that. He must have done it.

• 32:31Matt Kirshen?

  So the fact that Einstein didn't think black holes are real, and I do, makes me smarter than Einstein? Like, what are we...

• 32:37Speaker 03

  Just a little later, that's all.

• 32:40Janna Levin?

  If you time-traveled to before Einstein and believed in black holes, that would make you pretty smart.

• 32:48Janna Levin?

  Do we have one last? We've got a minute for our last cosmic theory, really quick.

• 32:51Speaker 03

  I didn't answer the question, but never mind.

• 32:53Janna Levin?

  I'm sorry, I know.

• 32:54Speaker 03

  I don't know, you need to make an artificial source to make an interference pattern. And that's why I was... I just don't think we can do it, unless, yeah.

• 33:00Matt Kirshen?

  So Mary, uh, not gonna tell ya, I don't think that's her real name, I'm almost guaranteeing that it's not, uh, says, "I asked this before as a silly question, but I've been thinking about it, maybe it's not so silly. If gravitational waves were represented by colors, what would they be and why or how?"

• 33:16Janna Levin?

  Hmm, well, yeah, I mean, the frequency of the sound can be translated directly to the frequency of light, which is a specific color.

• 33:23Speaker 03

  That's right.

• 33:24Janna Levin?

  So what colors would they be? They'd be, uh...

• 33:27Speaker 03

  Well, these would be way out of the eye. Completely out of the eye.

• 33:30Janna Levin?

  Your eye would have to be like the size of a huge radio, I don't know, very big.

• 34:01Janna Levin?

  Now, a lot of people are talking about the discovery, so let's give people a sense of what actually happened. It was about, what, 1.3 billion years ago? Two black holes collided. Now, those black holes might have lived together a long time. What about the gravitational waves when they were far apart, when they first formed black holes, when the stars died? What about those gravitational waves? You had an instrument up in 2000.

• 34:24Speaker 03

  Yeah. Well, let's be honest about why we didn't see it in the year 2000. That's what you're complaining about, right?

• 34:29Janna Levin?

  Well, it wasn't really a complaint.

• 34:31Speaker 03

  I think you are.

• 34:32Janna Levin?

  Those gravitational waves have been coming across us since multicelled organisms were fossilizing on the Earth.

• 34:37Speaker 03

  Let's start with what must have been the case with these. And I think this is probably going to hold, even though there are other ideas now about this. But, as you say, we saw the thing that happened about 1.2, 1.3 billion years ago. And we saw it at its end point, at the very end, when the two black holes were getting closer and closer. They were orbiting around each other. And then, all of a sudden, they hit each other, and they make a new black hole. That's what they do. They swallow each other as their event horizons come together. And you wound up with, let's say, there were two 30 solar mass stars to begin with, and you wind up with a 57 solar mass black hole when they make a new one. So the first thing you have to explain is where did that three solar mass?

• 35:19Janna Levin?

  They lost some mass.

• 35:20Speaker 03

  Well, they went someplace. Well, they went in the gravitational waves. And that's unbelievable when you think about it.

• 35:25Janna Levin?

  Right, so it's completely dark. None of it comes out as light.

• 35:27Speaker 03

  Nothing comes out in light.

• 35:28Janna Levin?

  If I pointed a telescope at these two black holes colliding, I would see nothing.

• 35:31Speaker 03

  See nothing, and that's one of the tragedies, because you'd love to be able to see something, so you could identify where it is. We don't have the faintest idea where it is in the sky, except for the fact that it hit Louisiana first.

• 35:45Janna Levin?

  From the southern sky.

• 35:46Speaker 03

  From the southern sky and went up. So we have sort of a banana in the sky where we think this thing comes from. But we have sort of 1,000 squared degrees of ignorance is what we have.

• 35:54Janna Levin?

  So now there's a black hole out there, and it's gone quiet, and we can't look at it either.

• 35:57Speaker 03

  Nope, it's gone. And you don't know where to tell people to go look for it. So that's sort of something we want to fix. But we'll get to how we fix that in a minute. But let's get back to what happened before we saw them, okay? And there, it's a tricky one. It depends how they got made.

• 36:12Janna Levin?

  Uh huh, yeah, how did those black holes form in the first place?

• 36:15Speaker 03

  And we don't know how it got made. And that's gonna be one of the more interesting scientific questions. As we, when we go back on the air and begin to see a lot of these things, we can begin to contemplate. But there are two ideas that people had right away. One thing is, a star collapses, that's called common envelope, and they come together and they make two black holes. By the way, Hans Peter explained to me many years ago, just like Kip, that that's the first thing we would see.

• 36:36Janna Levin?

  Oh.

• 36:37Speaker 03

  Okay, that was back in 1990. While he's still alive. Uh, so that's one thing. That's one method, that could be. Acquires a star that's pretty heavy, 60 solar, 70, 80 solar mass. A big star, a big mammoth star. So where did that come from? Okay, that's a question. But then the other possibility, which is not quite as dramatic, is that we have things which are called globular clusters. What are those? Those are regions in our galaxy, and every galaxy has places where a lot of star formation forms simultaneously. And so here, a bunch of stars all zipping around, and there's a lot of probability that maybe three of them will get together, bang into each other, and it has to be orchestrated properly, okay? And so they make a thing that's a black hole. Or maybe they have to make two black holes.

• 37:18Janna Levin?

  Now, why can't it just be a big star that died and made a black hole? It's too heavy.

• 37:22Speaker 03

  It's, well, it's, yeah, be careful, Jenna. It could be that, and people are thinking that. And some people even, let me now go on, these are the-

• 37:29Janna Levin?

  It's a decay into a very technical conversation.

• 37:31Speaker 03

  This gets into something really quite tricky, but let me say that's what-

• 37:33Janna Levin?

  What about the metallicity of this?

• 37:34Speaker 03

  Ah, no, no, no, no, come on, let's get away from that. That was about to be my question. No, but your question, you were gonna ask that, right? Yeah, I was gonna ask that. Okay, well, to hell with the metallicity for a moment.

• 37:42Janna Levin?

  So, so we only see the final fraction of a second. How much of that collision do you actually detect? Did LIGO detect?

• 37:48Speaker 03

  LIGO detected only about point two, let's say a quarter of a second of this whole thing.

• 37:53Janna Levin?

  A quarter of a second, so it was emitting the gravitational waves, it just didn't get loud enough until that final quarter of a second.

• 37:57Speaker 03

  Well, be careful, it's two reasons. Yes, you're right, but the real reason we didn't catch it is because our detector can't detect anything with very low frequencies. As I told you, it goes from the bottom of the piano to the top of the piano. So this is a rumble, once they're very far apart. Those stars, if they have been stars, if they started far apart, they might not have. You don't know that. Suppose, like every other thing, they started far apart. Then they would be going very slowly around each other. Hours, periods of hours.

• 38:25Janna Levin?

  And that would be low frequencies.

• 38:26Speaker 03

  That'd be very... We don't have any sensitivity, but something later in the history of man will have that sensitivity. It's called LISA. That's the space version of LIGO.

• 38:35Janna Levin?

  I love your optimism.

• 38:36Speaker 03

  Well, it's going to happen. Maybe not mine, but in your lifetime.

• 38:40Matt Kirshen?

  I'm building my own LIGO at home. What kind of scale should I aim for?

• 38:44Janna Levin?

  Do you know what actually happened to me? I went to the LIGO lab. I am not actually an experimentalist in the collaboration, so I haven't signed the memorandum of understanding. And there are certain things I'm not allowed to know. But I was looking at the schematic of the lab, and I was like, "Why am I allowed to see this?" And somebody said, "What, are you gonna go home and build one?"

• 39:00Matt Kirshen?

  Yeah, yeah, I am. Just you watch me. And then everyone's gonna be really embarrassed when you've done one for like...

• 39:06Speaker 03

  Well, I'll tell you, if you come up with a clever idea that doesn't need something so big. And people at one time thought, "Maybe optical fibers." I won't go into it all. None of these ideas have worked out, but people are all the time thinking about, "How could they make a small version of something like this?" That is as sensitive. Let me go back.

• 39:24Speaker 03

  What you have is these big things that they're very... Let's suppose they got started separately. And they are still bound to each other, and they eventually oscillate, and they get closer and closer. And they're losing energy to gravitational waves, which we're not detecting because it's outside of our band. Then we detect it just as it comes into our band.

• 39:40Janna Levin?

  I see.

• 39:40Speaker 03

  That's the most likely explanation, but there are others too.

• 39:44Janna Levin?

  Now, you were really hoping for the centenary, for the first detection. So here, you've been building this thing for 50 years, Ray. I can't tell you how many times somebody said to me, "We better go ask Ray." On-site, you're doing experiments, you're walking the beam tubes, and you want it to be 2015. You wanted that so badly, I know.

• 40:04Speaker 03

  16 or 15 was good, 16 was the latest.

• 40:06Janna Levin?

  Okay, so you were willing to take 16, and then if not that, you would find an Einstein paper that was, you know...

• 40:11Speaker 03

  2018 paper, but that was it.

• 40:13Janna Levin?

  No, a lot of people told me, "2018, don't expect a detection before 2018." But on September 14th, 2015, this struck. It must have blown your mind. I mean... What is the experience of waking up that morning and checking the logs?

• 40:30Matt Kirshen?

  I'm already thinking it was like it was the practice run that like that wasn't meant to be the run that detected anything, right?

• 40:35Speaker 03

  You're absolutely on the mark. That's correct, yeah. It's even worse than that. What happened is we didn't expect this and when, as Chana points out, I happened to be on vacation. I had been at the site the days before that and I almost screwed it up. Do you know that story?

• 40:50Janna Levin?

  Yeah.

• 40:51Speaker 03

  But I do want to tell you the story because I was sent by my boss, Peter Fritschel, who is the young student that I had now as a senior member of this thing. He says, why, so you gotta go down there, fix the RF interference.

• 41:02Janna Levin?

  Radio frequency.

• 41:03Speaker 03

  Radio frequency interference and because it'll disturb the whole run. So I went down there and I saw what was really a big mess. I mean FCC, you know, the Federal Communications Commission would have sent their truck there and shut us off because we put out so much RF. And then I found out the problem was and I said to Peter, look, this is gonna take a week to fix up. I can't, I don't. They had a big conference and the reason why they told me no was they had committed themselves to making a run two days later.

• 41:31Matt Kirshen?

  They just left it like it was?

• 41:33Speaker 03

  It was a run and you had to, and he said, look, we have all these people coming from all over the country, all over the world, coming to the sites. We don't want to jeopardize this and the RF, if it's a problem, well, it can't kill us. And I said, no, it won't kill us for impulsive source, but if you're looking for periodic sources, it might. And so we took that gamble and Peter said, let's come home. Okay? And I thank God I went on.

• 41:54Janna Levin?

  24 hours later.

• 41:55Speaker 03

  It was about three, two days later. It was a Thursday. The thing happened on a...

• 42:01Janna Levin?

  It happened on a Monday.

• 42:03Speaker 03

  It happened on Monday, so it was four days later.

• 42:04Janna Levin?

  So you checked...

• 42:06Speaker 03

  And so you asked, what did I think?

• 42:08Janna Levin?

  Yeah, you check the log, you wake up, 8 a.m. in Maine.

• 42:10Speaker 03

  Well, I'll tell you what happened. It was really cute. I went to log, we were on vacation. My wife and son were with me and her, and his, and his wife. And I was looking at the log, which I do every morning, and I see this thing, which was very cryptic. It says, we're canceling a fix-it day. Now, we have fix-it day every Tuesday. We have running, in the middle of a run, even in engineering, when we find all these things wrong, we don't want to mess with the apparatus, but we do it at a certain time so both sites are dead at the same time. And they said, "No, we're cancelling." And so I look at the other site, same damn thing. "We're cancelling fix-it day." So I call up, "What's the hell, what's going on?" And they say, "Well..." And then it didn't take long, I began to get email. And then very quickly, within about half an hour after that,

• 42:55Speaker 03

  I saw an absolutely magnificent curve. It was this signal, which now is on people's dresses, it's in everywhere. And it was this binary black hole, thirty solar masses. I look at it, "Holy mackerel, this has got to be a fake."

• 43:09Matt Kirshen?

  Really mackerel that you said?

• 43:10Speaker 03

  Yes. Well, maybe not. I'm trying to be careful.

• 43:13Janna Levin?

  He's cleaning it up for air. If I know you, Ray, that's not what you said.

• 43:18Matt Kirshen?

  Holy smokes, do you whiz?

• 43:19Speaker 03

  No, no, no.

• 43:20Matt Kirshen?

  You're a 1920's paper boy. Say, "Mister, mister, we got some scoops."

• 43:25Janna Levin?

  It was really something when in February, all these months later, the announcement was made, and everybody just shared in this incredible excitement. That was really a moment in history.

• 43:33Speaker 03

  It was. Well, we did a lot of work between the time we found it, and then because we didn't believe it. Let's be honest, I mean, Jana, that was such a big signal. We never expected such a big signal.

• 43:44Janna Levin?

  Right, amazing. Okay, we're gonna go quickly to the lightning round, are we ready?

• 43:49Matt Kirshen?

  All right.

• 43:49Janna Levin?

  Rapid fire.

• 43:50Matt Kirshen?

  Carl West on Instagram says, "Would it be possible for gravitational waves to alter matter as it passes through? E.g. if matter was too close to the source, the gravitational waves could have become damaged or altered by the sheer energy or force of the waves propagating through the fabric of spacetime."

• 44:04Speaker 03

  That's so easy to answer, so fast. Gravitational waves are the most penetrating things that man has ever encountered. They go through everything. Nothing's gonna stop them.

• 44:13Janna Levin?

  They go right through the earth.

• 44:14Matt Kirshen?

  All right. "Do gravitational waves cancel each other out like sound waves?"

• 44:19Speaker 03

  No.

• 44:21Speaker 03

  Beautiful. Unless let me be parenting, but they could, but it would be taking enormous amount of precision to do that. You could have a compression while the other one has a rare fraction.

• 44:33Janna Levin?

  Like water.

• 44:33Speaker 03

  It's not impossible, but my god, in the real world, it's not gonna happen.

• 44:37Matt Kirshen?

  All right.

• 44:39Matt Kirshen?

  If two black holes collided near us, would the gravitational waves be strong enough to disrupt our own magnetic field? What could happen because of that clash?

• 44:47Speaker 03

  Well, if that collision happened in our solar system, we would be, we might not even be here.

• 44:53Speaker 03

  And I'll tell you what happens.

• 44:54Janna Levin?

  In our solar system, yeah.

• 44:56Speaker 03

  Yeah, we would be stretched and compressed in such a ways that things could easily come apart.

• 45:01Matt Kirshen?

  That question, by the way, was from Mike Schneider on Facebook. David Norio on Facebook says, "Why are we referring to gravity as a force since it's the result of the curvature of spacetime? And what about the other forces? Are they also the result of something we can't see yet?"

• 45:16Speaker 03

  Well, that's an interesting question, and I can't answer it because it may very well be. We don't have the final theory, but maybe you should try that.

• 45:22Janna Levin?

  We're loose in this language. It's true that Einstein made us realize that in some sense, gravity's not a force, that we're falling freely in a curved spacetime. We're not actually being touched and pulled upon. But there's another way to look at it that makes it look like a lot of the other forces. So, electric fields permeate space and affect things. Gravitational fields permeate space and affect things. There's a way of making them sound more parallel. And there's always force carriers: gravitational waves, light waves, weak force carriers.

• 45:47Speaker 03

  You can recast gravitation, as Steve Weinberg did, for example, as a field theory, if you want. You don't have to use Einstein's beautiful theory.

• 45:55Janna Levin?

  Well, what people say is if Einstein hadn't discovered curved spacetime theory, we'd be talking about it in this much more particle physics-y sort of a way.

• 46:03Matt Kirshen?

  All right. The Scarlet Speedster on Twitter says, "How do gravitational waves affect time slash perception of time? What would need to occur to have significant changes?"

• 46:15Speaker 03

  Well, I don't know if I can answer that. The metric that I use does not have the clocks perturbed.

• 46:20Janna Levin?

  This is tricky.

• 46:20Speaker 03

  Either gravitationally.

• 46:21Janna Levin?

  Yeah, so it's like, what I call left isn't what you call left. It's a mixture of your left and right. We tend to orient our spacetime so it's only the space that changes, not the time. But you could orient your spacetime differently, where you would measure it being in the time direction. It's not easy stuff.

• 46:39Matt Kirshen?

  All right. Tony Hale on Facebook says, "Do gravitational waves reflect light? And if so, could you dial in an image like flipping a page in a book? If we can't see our galaxy in the past, but the light reflected from our galaxy is traveling faster than we are, would that mean we could see an image bounce back at us?"

• 46:56Speaker 03

  I don't think that'll happen, but let me tell you something. There's a very nice way of thinking about gravitational waves affecting the propagation of light. You don't have to have mirrors doing it. In other words, they interact to make sidebands on the light. That's a complicated way of saying it, but you... For example, some of the other ways of looking at gravitational waves do not use mirrors. Like, the pulsar timing does not use mirrors. So consequently, there's an interaction between gravitational waves and the propagation of light.

• 47:23Janna Levin?

  Yep, that is some hard stuff. I'm not even going to try to clear it up, because we're at the end of our show. Thank you so much for the excellent questions. It's been a great show today. Ray, always an honor and a pleasure to talk to you. Matt, so great to have you on. Thanks so much for being here with me. This has been StarTalk All-Stars. Thanks for listening. See you in the multiverse.