StarTalk Radio - StarTalk Live! LIGO and the Black Hole Blues (Part 1)

Episode Date: July 29, 2016

Everything you ever wanted to know about gravitational waves, explained by Neil Tyson, Eugene Mirman, cosmologist Dr. Janna Levin, LIGO astrophysicist Dr. Nergis Mavalvala, and comedian Michael Showalter. Recorded live at the Count Basie Theatre in Red Bank, NJ. Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. Welcome to StarTalk Live! I'm Eugene Merman. It is my great pleasure to bring on the amazing, the wonderful, Neil deGrasse Tyson! Neil deGrasse Tyson! Dude.

Welcome to StarTalk. This is StarTalk Live. Tonight's topic is everything you ever wanted to know and perhaps never wanted to know about gravitational waves moving through the universe, washing over Earth itself. Where'd they come from? How do we detect them? Who's doing the detecting? And what is the future of that exercise? And I have experts this evening to help us through.

Give a nice, warm New Jersey welcome to Jana Levin. Jana Levin, come on out. Jana Levin. There she goes. Jana. How you doing? She's professor of physics and astronomy at Barnard College and just came out with a book all about black holes.

Black hole blues. You're supposed to say it in a DJ voice. Black hole blues and other songs from outer space. This is the black hole blues and other songs from outer space. That is the title of her book. We talk about black holes trying to talk to us. Yeah, they're singing. With their soundtrack.

Yeah. Okay, very cool. And so not only that, someone who is an expert not only in cosmology and has written a book on this subject, we combed the land to find someone who actually worked at the facility, the Laser Interferometric Gravitational Wave Observatory, the actual place that made the discovery. Give a nice warm New Jersey welcome to Nergis Mabalvala. Where is she? Here she goes. She's a professor of physics at the Massachusetts Institute of Technology,

and you worked on the actual facility, at the actual facility. I did, I did. I've been doing this for 25 years. Yeah, okay. Did you start when you were eight or something? Before I was born. Before you were born. That's how you start. You got to start them early, people. So Eugene, who did you bring today? And today we have an amazing comedian, one of the writers or creators and stars of Wet Hot American Summer, Michael Showalter!

Michael? New Jersey Joe! Hi, do I go over there? Oh, you're sitting over there. Welcome home. It's good to be home. Yes, I'm a Jersey boy. Is that what you mean?

Yes. I got to ask, what exit? Nine. Thank you. That's the exit one takes to get to Princeton, New Jersey. That's where I'm from, Princeton, New Jersey. You are from Princeton. Okay. It's cool. Just showing off some Jersey flu flu. I grew up on the mean streets of Princeton So Nergis tell us all what gravitational waves are and in the green room I call them gravity waves and you said no they're not graduate the gravitational waves and that sounds kind of semantic to me and I don't know what you're talking about

There's a big difference Gravity waves are local to our Earth. They are actually waves, seismic waves. They're part of density movements in the Earth, whereas gravitational waves are cosmic. They come to us from the universe. You're telling me that the geologists got to the word gravity waves first. That's absolutely right. Although, actually, gravitational waves have been around for about 100 years as gravitational waves, but I think the geologists probably had gravity first. Yeah, but the universe has been making gravitational waves for billions of years.

Yes, right, since its inception. And the Earth's been doing it for a long time, too. You just noticed 100 years ago. To be fair... No, you're not going to say we're the geologists. Gravity didn't start around the time they killed McKinley. It's true, but gravitational waves started at the very beginning of the universe. Gravity waves came about when the Earth was formed, so much later.

Okay, agreed. So I think gravitational wave wins the race. Yeah, yeah, okay. I will promise I'll say gravitational wave so we don't confuse the geologists in the audience. Okay. Or the comedians. Now, Jana, I have some issues that I want to take up with you. You keep talking about waves. I get it. They're waves. But now you're talking about

the blues and music and sound. And we knew from the movie Alien that no one can hear you scream in space. Actually, we knew it well before the movie. That's when it became a publicly thing. So why this urge to always analogize it to sound? I think that's misleading the public. Yeah, it's actually stronger than an analogy. So let's say two black holes collide.

They actually cause- Just for instance. Just for instance. Yeah, okay. This is the kind of thing, you know, we spend our energy on. And they will literally ripple the shape of space-time. Space-time around the black holes will squeeze and stretch and emanate outwards as a wave, like fish swirling on a pond. I prefer mallets on a drum and the drum rings. And so these waves emanate outwards. Now now if you were close enough to the black holes

even though it's empty space and there's no air it's technically conceivable it would ring your eardrum and you would actually hear from the squeezing and stretching of your ear mechanism well no if it squeezes your cranium, you're just gonna die. Even if it squeezes it just a little bit. You don't want a sound to be so loud that it's squeezing your cranium. Yeah. Okay. But if it rings the eardrum mechanism, you would technically hear the black holes, and then you would die because you'd be too close to the collision of two black holes.

Right, you'd be incinerated. Right, right, right. If you hear a black hole... Eventually you die. And is it like a sonic boom where you're like, what's that? And then you go back in time and explode? I don't know what you're talking about. Do you go back in time with sonic booms?

No, but you said that it ripples time space, and I thought maybe time would be affected. Yeah, that's true. Your time... Ha ha! Your time relative to somebody else's would be affected. That's good enough. All right.

So, Nergis, you were part of the team that made a discovery. And so tell me about that discovery in particular. Okay. And it's recent. It's recent news. It's very recent. So I'll tell you the date. Go for it. It was September 14th, 2015, and our detectors

began to sing, just as Jana says. We recorded a signal that we could turn into a sound, and it turned out to be the sounds of two black holes colliding. Where? Quite far away, thankfully. Our eardrums would not ring from this because we were thankfully far away. 1.3 billion light years away. So quite far.

Okay, so... How many hours is that just to get a picture? So what you're saying... Wait, and how big were the black holes? So the black holes were 30 times more massive than our sun. So again, rather fat for those kinds of black holes. Okay, so it was two black holes, 30 times the mass of the sun, colliding 1.3 billion years ago

before the Cambrian explosion of life on Earth. So there were single-celled organisms swirming in tide pools, and that's when this event happened. And then this ripple moved through space. This disturbance in the fabric of space-time propagated at the speed of light, and it's been going for 1.3 billion years,

and in the interim, life evolved to make vertebrates and primates and humans. And then humans develop civilization and agriculture and technology and physicists and Einstein and the prediction and LIGO, the experiment, and you. And then you turn on the machine and you detect it. Yeah, that's about right. I do want to say it was me and a thousand other colleagues. Okay, but we got you here now. Yes. Tough luck.

What were you saying, Janet? Okay, but we got you here now. Yes, that's right. Tough luck. What were you saying, Janet? Well, I was just going to say, it was when the discovery hit, the experimentalists like Nergis were still doing tests on the instrument. So they're theorists and they're experimentalists. Yeah, I'm a theorist. In a world they work together.

Yeah, that's an ideal world. And are you guys in reality enemies? Well, we're often, sadly, in reality a little disconnected. So the interesting thing from me writing the book was I became so enamored of the experimentalists and what they were doing. I mean it's one thing to kind of pen and paper fantasize about black holes colliding. I was like, are you people seriously going to try to do this with like metal and glass? That's insane. And a lot of people thought they were insane. It was not a popular Seriously? Going to try to do this with metal and glass? That's insane." And a lot of people thought they were insane.

It was not a popular experiment. If you had asked people even in August, many people in astrophysics would have said, this isn't going to succeed. So it was really just a dramatic thing that happened that as soon as it went on, they weren't even ready, but as soon as it was on, bam. And when the the news hit it reached into pop culture it was page one banner headlines and in fact there's a storage company in Manhattan because Manhattan mini storage

and they have these clever ads on the sides of buildings and I've got it written here one of them said scientists found gravity waves in outer space. If only we're that easy to find an apartment in New York with a walk-in closet. Rent your own personal closet space. Manhattan mini stores. Did they pay you for that? No, no, that was not an advertisement. So they went right in to fold in the discovery into pop culture.

So I was very impressed by that. Did you have any clue it would be that popular? No. I actually was pretty sure that the scientific community would be very excited by it. But I don't think almost any of us could have predicted how much it moved people who just like to see science succeed. You don't have a machine that also detects how exciting certain breakthroughs will be to regular people?

I'm working on it. Yeah. have a machine that also detects how exciting certain breakthroughs will be to regular people. I'm working on it. Yeah, so I was impressed by it. I think people like big problems and cosmology and black holes. It had all the trappings of the news story that should make banner headlines. And when you were working on this, isn't it true that the the discovery paper was published, when was the paper published? The paper was published on February 11th 2016. Okay so there's a time delay between the detection and the paper. Why? It's a huge amount of work that had to be done from the time our instruments recorded the signal to the time the paper was ready,

here were the steps. We had to first make sure the signal was real, because these detectors, I mean, the signal is really, really weak, and there's all kinds of other things that masquerade as signal in our detectors. We had to make sure the signal was real. We had to make sure it was from the universe and not from one of our colleagues injecting it into our detector, which sometimes happens. We do that to ourselves. What does that mean? It's self-inflicted pain.

It's like a scientist outside the microphone going ahhhh So you might have just detected someone playing a guitar? You could but even more than that it's self-inflicted pain in that this we the scientists go into our own data and inject signals, fake signals, and then ask ourselves, could we find them? It's like being hide-and-seek with yourself. Yeah, it sounds normal. Now I get why if you ask people in August, they'd be like, those people are cuckoo. Okay, so you've got to make sure the signal is legit.

That's right. And then you publish. So the general public doesn't know until when? February 11th, when we announced it. Okay. And just FYI, I visited one of the LIGO facilities after apparently they had already made the detection. Nobody spilled anything to me. There was no winks and nods?

No, no, they didn't wink. They were very smiley though, I remember. Now, Janet, this search has been going on for decades. Yeah, for decades. And you chronicle this in your book, don't you? Yeah, so when I started becoming so enamored of the physicality of this machine that they were building, you know, these are huge machines. They're four kilometers long each, and there's two of them, one in Louisiana and one in Washington

State. The first prototype was built by somebody named Ray Weiss from MIT, who's a colleague of Nergis's in the late 60s. And that's when it started. He dreamt up this idea of building it, and the first one that was built was like a meter and a half. This is a guy on his own. And 50 years, people like Ray were working on this,

and slowly Kip Thorne comes in and Ron Drever and they're really just three of them. Kip Thorne is a cosmologist at Caltech, perhaps in pop culture best known for being a co-executive producer of the movie Interstellar, yeah. Yeah, so

right. Got all the right people on it. Yeah, you got right people on it. So before Kip was a movie producer, he was a very famous astrophysicist. So 50 years they pushed through from a one and a half meter long instrument, finally realizing, you know, Ray says he finally realized one day that this had to be big. And now it's four kilometers long and they're in vacuum which is just a very intense thing to do. You vacuumed out a four kilometer long tube.

That's right. In 1998 the vacuums have been there for this instrument is when they pulled the vacuum. So if the vacuum had broken between 1998 and now, people said we all would have gone home. Like that is an expensive and

difficult procedure so they this was a really arduous climb for them just to be just to clarify so the history of astrophysics probing the universe is one where we study light right initially visible light Roy G Biv you know Roy G Biv yes we know you know Roy eveniv? Yes, we know. You know Roy? Even I do. Yeah, yeah, yeah. Especially Biv. Red, orange, yellow, green, blue, indigo, violet. Seven colors named by Isaac Newton, but there are many more colors than that.

He had a mystical fascination with the number seven, so he just picked seven colors and attached it. So, then we find out there's colors outside of that range. There's infrared and ultraviolet and x-rays, gamma rays, radio waves. So, that becomes modern astrophysics and it's all forms of light. And now you guys have come up with another kind of telescope to find another kind of wave in the universe, the gravity wave. And this is just a stunning fact that we've opened up a whole new, the first ever discovered gravity wave.

And so now we're no longer restricted to light itself. Yeah, that's right. Everything we've known about the universe, more or less, I mean, very nearly everything comes to us from light since Galileo. We've made this silent movie of the universe through everything you've described, all those colors. When Nergis and her colleagues are working on the instrument in the control room they're listening to it through a speaker system. This is not light and what they recorded was not a picture. It's really something fundamentally different. It's like we've gotten the soundtrack. So you're saying this thing

sounds like something. It does and you know let me add if we had pointed a telescope at those black holes we would have seen nothing. Even a telescope that's beyond our imagination, the best telescope you could imagine, probably would have seen nothing. What if you had pointed a very powerful microphone? That's what they did. So I think we have that sound. We can play that sound. We have the sound? Yes, we have the power to push a button and play the sound.

We could sing it. Can we get that? Let's switch. I have no idea what that was. I believe that was from the third episode of Next Generation Star Trek. Right, right. The sound of the engine in the background. Yeah, exactly.

Wait, wait, so what was that low rumble? So there's two versions of the sound that you heard there. The low rumble was the sound as we recorded it in our signal. So what we do is we record a signal, and that signal actually you can make a graph of it on a computer, or you can actually port it out onto a loudspeaker and hear it. And that's what we just did. We turned the signal into a signal that the loudspeaker could play back.

So the low rumble is actually just the hum of noise in the detector, and superposed on that was the sound of these two black holes colliding. Now if there were no noise and if these were black holes that fit my voice range they would have sound like this. It would have been a low rumble that gets to a higher frequency and higher amplitude. It's gone and at the end they would have collided. That end would have been the colliding. So what we heard there initially was just the original sound, and they sound like a thump.

It was... Did you just imitate two black holes colliding? I just did. I was expecting applause. Give me a second to figure that out. Come on, people. I have a question, which is a very stupid question. This happened billions of years ago?

1.3 or so. 150 billion years ago? No, 1.3 billion years ago. Give or take a couple hundred million. Give or take a couple hundred million. So how then do you know that it was black holes colliding and not anything else colliding? In fact, you out there in space going... Like how, if this happened so long ago, how can you be so sure that it was black holes?

Yeah. Yes, all right. It's a good question. So Einstein 100 years ago gave us a theory of gravity in which you could start to predict what signals from black holes could look like. And in fact, Joanna has spent much of her career solving those equations that Einstein gave us and predicting what the signal from black holes should look like. And that signal looks different than signals from other kinds of stars. So...

Just if I can add there, so Einstein lays down the theoretical framework from which you can derive predictions for all manner of things, and that is a testament to the potency of what he laid to tracks 100 years ago. Absolutely. So continue. Yeah. Yes. And so maybe, Jan, you want to say a little bit about what the signals would look like

you actually calculate them. Yeah, well, I think one of the ways bit about what the signals would look like. You actually calculate them. I think one of the ways to answer that question is, let's say you heard a ringing drum. You would be able to reconstruct technically from the sound of that drum how the mallets were moving. And so the black holes are the mallets in this example. And you can tell if you're listening to an orchestra or you're listening to a band how they're hitting the drum.

And so if we're able to correctly predict, from Einstein's theory, the motions of the black holes, which we can do in great detail, and we can then predict how the drum rings, we actually can reconstruct the source from the sound. I just realized, we're talking like everybody knows what a black hole is, but let's just make sure we're on the same page.

Sure. Tell us. So a black hole is the death state of a very massive star, but we think of it as a thing. And I really would like to convince people it's not actually a thing. After the star collapses, what it does is it curves space-time so strongly around it that not even light can escape. That's the famous saying about the black hole. And then the material in the star keeps falling. So if you go up to the shadow of the black hole, and it's a shadow because no light can escape, there's nothing there. The black hole is not a hot, dense object.

It's actually a curvature in space time. It's completely dark. The stuff that made it is gone. If you want to find out where it went, you have to go in too. Does it move around or is it there? The black hole moves around like any other object, but it's kind of like a place. Does it go far? Like will it come and does it eat planets?

We are orbiting a supermassive black hole in the center of our own galaxy. And we are technically falling into it. How slowly? Like how worried should I be yeah is it is it really cold inside a black hole that's an interesting question to wear like a sweater yeah it is probably deathly cold yeah but it's not dark inside the black hole because the light from the universe can fall in behind you and you can see it it's only dark outside the black hole. Black holes are dark on the outside, not on the inside.

Plus, to be clear, when we use the word hole in modern and everyday parlance, it's like something you fall through and you just fall through. Whereas a black hole is a hole in every direction that you approach it. It's a spherical hole. It's a spherical hole. So you can fall into this hole no matter which way you approach it. It's a spherical hole. It's a spherical hole. So you can fall into this hole no matter which way you approach it. Yes, you would approach this region, this spherical region, where you'd have to travel faster than the speed of light to escape. So you have no

choice once you hit that sphere but to fall forward. In fact, it's almost like you're falling towards the future because space and time sort of switch places I'm not making this stuff up I'm not making this stuff up I'm not making this stuff up space and time switch places inside the black hole don't just say that and don't explain it yeah it's a way to go into the future

no problem next yeah I know we got that next yeah you want me to really explain that? I can try that. Okay, no, you wanna go, we can go forward without the material. No, no, we wanna know, I was kidding about this. We don't wanna know how time travel in a black hole works.

So famously, Matthew McConaughey went into a black hole in... In his career? Yeah. Word. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah.

Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah.

Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah stuff up? Yeah. Or is your space and time switching empower that?

I don't think the space and time switching empowers it, but I can say this much. The black hole, however big it is on the outside, can be very deceptive about what's on the inside. The black hole can be much bigger on the inside than it is on the outside. Really? Yeah. Like a TARDIS. It's a TARDIS. Like in Doctor Who. Oh, my gosh. Like a TARDIS. It's a TARDIS. Like in Doctor Who.

Oh my gosh. Like a TARDIS. So the TARDIS is, wait, so what's the? Wait, wait. For those who don't know the TARDIS reference, it's like. Get out. Get out. Wait, wait.

No, there are other references. Ready? It's like Mary Poppins' carry bag. Very good. But she pulled a whole plant out of the bag and pulls her like a... Okay. That's just evidence that Mary Poppins is herself. Wait, did you just describe a black hole? I described something that's bigger on the inside than on the outside.

But it's her bag. Okay, so thanks for that mini tutorial on black holes. We'll figure out how to invoke them. I'm really going to start working on this for real now. Did I interrupt you a second ago? I don't think so. It's just all very confusing. There was a moment in my life where I like people would say like how good Radiohead is and I would be and I didn't

Understand but then I got it and I Want to know I Want to know was there ever a moment where you didn't understand what a black hole was and then all of a sudden you go oh I get it now and will that moment ever occur for me I'm only gonna answer the first question now so I I before I started studying the mathematics of it was frustrated too because you're just taking somebody's word for too because you're just taking somebody's word for it and they're just saying these crazy insane things that are seem so

implausible and whenever we get crazy letters from people it's usually just stringing together words like this that sound kind of fancy but if you take the mathematics of Einstein's theory of curved space-time you start and you you just really spent a lot of your energy on it so it wasn't just a long process no and and it's and it's very and it's a spectacular I really think of my life as before I spoke general relativity and after okay so in the before yes. Yeah, you have to earn your fluency. Yes, yes, absolutely. Okay, and you too, Nergis?

You have to earn your fluency? Yes, and you know, the story's not over yet. I don't think we fully know what happens inside of black holes. We don't know how to explain the singularity. We have ideas, but any one of them could be true. What are like just six of them? Well, the one- What's the most popular? What's singularity?

Ah, the singularity. Oh my goodness. It's a point in space that's smaller than a point. Can't you see? Stupid. Such a stupid question. Everybody knew that. No, but in all seriousness, could you somehow connect it to Mary Poppins' handbag? I think there was a singularity in there. What do you think? At least she had access to a higher dimension. That's right. Before we go to our first break, let me just clarify something about the detection the the LIGO

detection the as I understand it you turned on the machine to start taking data and within a week you got the first detection yeah actually less than a week it's true how much time? About two days. We've been trying 50 years to detect gravity waves. Hey, I haven't been trying for 50 years. Give me a minute. We've been trying 50 years to detect gravity waves, and a wave born 1.3 billion light years away, traveling for 1.3 billion years, you flicked the switch and you detected two days later? Yes.

Okay. She's cocky about it. I know, right? Have you detected more since then? So we've certainly seen some small evidence of smaller black holes than the two that we're describing and there's more data in the can that we're still analyzing, so probably there's more there, Maybe not. That would be amazing if it's like a fluke that you found. No, so I think it's not just pure fluke.

I mean, we turned on this machine after a major upgrade. It was down for four years after the first phase, and it had quite a bit more sensitivity, particularly in certain frequency bands where you shouldn't detect such signals. So I don't think it's a total fluke that we turned it on and we'd never seen these before and suddenly we did. We've made a machine we'd never made before.

It was a damn good machine. Okay. She said damn. We'll have to bleep that. We made a damn good machine. But my issue is not that you detected it in two days, but that doesn't it tell us that 30 solar mass black holes

are colliding every couple of days somewhere in the universe? It should tell us that if we see enough of them over some observing period. So yes, you don't expect them to be at completely, at even time spacing. Of course not. They come sort of every now and then. I'm just saying after 50 years you turn it on, you detect it in two days, this stuff is going on all the time as far as I'm concerned. Yes, yes, I agree.

I think anybody... Because nobody talks about it. Okay. Okay, so we agree on that. Yes, we do. This has got to be a way more common phenomenon than people had imagined previously. Yes.

Okay, cool. Well, after the break, we'll find out more about the people behind LIGO and the incredible 50 year quest that led to this amazing discovery on StarTalk! Cool! We're live at the Count Basie Theatre in New Jersey. This is Start Off. We are talking about gravitational waves propagating through the cosmos.

And Jana, your book, you started this book not knowing that they were about to make a discovery and then they made a discovery. So did you have to change up your plans? Well, actually, I was two years late on delivering this book, which was perfect. It dovetailed. I printed the book out for Ray Weiss, one of the original architects, and Kip Thorne, who we've talked about. I printed a copy for each of them on September 14th, just by coincidence, and sent them drafts. And I remember Ray was kind of getting agitated, and he's like, what are you going to do if there's a discovery? But, you know, he's not allowed to tell me.

So I loved that I could write the book without knowing if they succeeded, because the book is really about the campaign. It's really about the tension. I mean, even in the close of the book, Ray's saying things like, if this doesn't detect black holes, the thing is a failure. I mean, that's an incredibly bold thing to say in August 2015 from the original designer of the machine. And so, but I got to write an epilogue of redemption, you know.

And so they included me in the discovery a few months earlier. And Nergis was telling me on the way over that there was a lot of discussion about when they could tell me which is really really sweet so before um before I went to press they gave me the chance to write the epilogue so I kind of love it because the book is as though you don't know the conclusion until you actually get to the close of the story and so how much money has been spent to make this happen? About a billion dollars integrated, the experiment costs. Okay, so a billion, we've got to say it in a Carl Sagan way, a billion dollars.

A billion dollars. It's a lot of dollars to say at the end of the story if we don't discover black holes as things of failure. Does it end with, imagine how many pants we could have bought. Right. So, as we said earlier, Albert Einstein, I,

you said he came up with his general relativity a hundred years ago, but I didn't see anybody talk about at the time, and I've been screaming loudly, that Einstein also laid the foundation for the laser, which is a fundamental part of the technology of LIGO.

Could you tell me how you're using lasers? Yeah, so it's the L in LIGO, it's laser. Yeah. Yep. So that was, you know, if you ask why was it that, I mean Einstein made this prediction a hundred years ago, why was it in the 1960s, in the late 1960s that Ray Weiss came up, and others, but he came up with sort of designing this instrument that could measure it. It was the invention of the laser in 1960, the laser was invented in 68, Weiss had started

to think about using it. And the laser is fundamentally our first foray into quantum light. And Einstein sort of laid some of the groundwork for quantizing light. So I think it's very incredible that he gave us not just his theory of gravity, he also gave us some foundational ideas for making lasers. So Einstein laid down general theory of relativity, which predicts the existence of gravity waves. It predicted, later discovered, the existence of black holes.

He then lays down the theoretical construct for lasers. Then 100 years later, you use lasers to detect gravity waves that had just been emitted by two colliding black holes. Yes. So that tells me Einstein is just the bad assest person there ever was. He's the man. I mean think about what, think about that. Just so you know it was you know it wasn't easy for for Einstein to do all of this. He kept changing his mind about whether or not gravitational waves are real. So he would write papers, say they were real, write papers, say they weren't real.

Does that mean he'd be right no matter what? Yeah, he'd write it. That's kind of cheap. I take it back, what I said about Einstein. It went on for decades. And at one point, he would write a paper saying gravitational waves don't exist. It would get accepted for publication. And he'd slip in a paper that said that they did.

Like, right as it went to press. So it was such a hard problem. And somebody once said, you know, Einstein, your name's going to be on this paper. You have to be very careful not to put your name on a wrong paper. And he thought that was hysterical. He said, my name is on plenty of wrong papers. So he wasn't afraid to be wrong. I wish my name were on as many wrong papers as his. So who were some of the key, so you mentioned Ray Weiss and Kip Thorne we've

heard and who else are key early players? So I think that as Jana's book tells us the Troika originally was Kip Thorne who was thinking about the theory and the astrophysics. How do you model signals of black holes or neutron stars that are orbiting and colliding into each other? Oh, by the way, in the movie Interstellar, co-executive produced by Kip Thorne, the name of one of the robots is Kip. That's what money gets you.

I'm just saying. I'm just saying. OK, go on. I interrupted. So that was K Skip thinking about sources and theory. There was Ray Wise who came up with the idea of using an interferometer, and actually, more importantly, that idea had been around at about the same time. What is that? What's an interferometer?

An interferometer is an optical device where you take a laser beam and you kind of split it in two paths. Nice. And the light travels along two paths and it comes back. Nice. And then it interferes. You can save your emotions for after she finishes. So you start with a laser, you break it up, you get them back together.

Yeah. And then you're like, now I get how gravity works. Yeah. But along the way, what happened, when you broke the two laser beams apart, if they travel different distances, then when they come back together, they act a little funny. They're a bit darker or a bit brighter. And why do they travel a different distance? Because the gravitational wave came through the detector.

Aha! See? I caught you! Now I get it. Right. So your two beams are otherwise identically the same length. Yes. Now a gravity wave washes across the detector

and makes the length of one different from the length of the other. Because it went into the future. And then you recombine the waves and now you have like a crest adding to a trough of these waves and they interfere with one another. And you can measure this.

We can measure that, and we can measure not just if crests line up with crests or crests line up with troughs, but lots of variations in between. So is it perfectly dark because troughs and troughs lined up, or is it perfectly bright or something in between? And that's how we make the measurement. We actually use the laser beam along one arm as a kind of a reference for measuring the light travel time

along the other arm. You just compare how long did the light take along this arm compared to the light along the perpendicular arm. Now, you've got two of these facilities. Why? Well, that's really important because the... And one is in Louisiana,

one is in Washington State. State, yes. So they're about 3,000 kilometers apart. Convert that to miles here, because we're Americans here. Eight. Eight miles. Trust me. So it's about 2,000 miles.

Yes, thereabouts. You say 2,000, okay. So why do we need two of them? In fact, there's actually a European detector in Italy as well called Virgo. And why do we need so many? So a couple of things. One is the signals are very weak. So how does this, can I say how the detector works?

Yeah. Do you want to know how the detector works? Okay. They don't get up and leave. No! Wait, wait, stop! Stop! As they start going for the exit. Yeah, we'd love to know how it works. So the way it actually works is that the gravitational wave comes through the detector.

It actually changes the distance between the laser and a mirror. In our case, in the case of LIGO the US detectors the mirrors and the lasers are separated by four kilometers so two and a half miles okay so and and what happens then is that our job then is simply to measure the change in distance between the laser and the mirror when the gravitational wave goes by compared to when it's not there. And now the problem is that the motion of these mirrors compared to the laser distance is tiny. The gravitational wave is really really really weak and so the motion we're trying to measure over

those two and a half miles is smaller than 1,000th the size of a proton. Okay, so it's a very small number. It's 10 to the minus 18 meters for those of you who think in those kinds of numbers. But really what you have to think about is that you start off with an atom and you get to something that's a thousand times smaller than the typical size of an atom. You have its nucleus in the center, a proton. And now we're thinking of something that's a thousand times smaller than the central nucleus of an atom.

And you measured that? We measured that. So you claim. Yes. Did you measure it with one of those rulers you get at Staples? Yes. And then at the end, they put a ruler. The little wooden ruler? No, it's more like one of the wheels, they put a ruler. The little wooden ruler.

No, it's more like one of the wheels that you use to measure more like the street. No, we measure that using the travel time of the laser. That's why the laser is so important. Okay, but you have two facilities. Yes, so why? Because the effect is so small. Now, we're trying to measure these tiny motions of mirrors, and everything on our planet wants to move those mirrors by more

than this passing gravitational wave. I remember when I visited one of the facilities, you come near the the beam, it says drive really slowly towards the facility because anything is going to jiggle, shake and bake your experiment. So how do you know you didn't detect me driving into the facility? That's why we have two because there's not two of you at, you know you didn't detect me driving into the facility? That's why we have two, because there's not two of you at 3,000 kilometers apart by the same time. How do you know? Or how do you know that there isn't another car with another person?

So the way that you know is that the detectors at the two observatories are instrumented with all kinds of other instrumentation, like seismometers that would measure you going by and so we take those we can remove those events from our signals and now what happens I think about the black holes we did detect what we saw was a signal that arrived in our Louisiana detector first and then seven milliseconds later that same set of wiggles and bumps that same signal seven thousandth of a second So seven thousandths of a second. Yes, seven thousandths of a second later, it arrives at our Washington detector.

And that told us something very important. It told us that the wave was coming in from the south, traveled through the Louisiana detector, and then continued on its way, and seven milliseconds later, which is about the light travel time, you know, these waves also go at the speed of light, and it registered in the Washington detector. So it's not like a thing moving through the air, it is the rippling of the fabric of space-time shaking and baking Earth being felt by one detector seven milliseconds after the other. Yes, that was what it was.

And that's what those two detectors are for. When you turned on the machine and you heard the signal and you were like, that's the real signal, did you guys then have a party? Yeah, so when, you know, in part because of the history of false starts in the field, many of us also have the psychology of, oh no, that can't be real. So we looked at this beautiful signal and we were trying to talk ourselves out of it. But eventually after we did enough testing, it was real. And then yes, we did have a party.

You realize it wasn't me driving down the street. Did everyone get drunk at the party? Did you all have to come home drunk and go like, no reason? Because the discovery paper has a thousand people on it. How are a thousand people going to keep a secret? Huge party. We did pretty well, not perfectly. You did damn well. I'm there and they're all just smiling ear to ear and nobody told me a damn thing. And what percentage sure were you that you were going to hear the signal? Yeah, so there's a real mathematical process by which you can ascribe a number to how sure you were

and in the case of this signal it was we were sure at the level of one in two hundred thousand years. Now what does that mean? It means if we ran our experiment for two hundred thousand years there was a chance of of once in those 200,000 years getting a signal that was like this. Getting a random signal. Just from the noise of the detector. But then you got it in less than a week. No, but the actual, you mean a false detection is what you're talking about.

What's the confidence then in the signal? How... Right, so I think what Nergis is saying, look, the chances that that was just false, that the two detectors just happened to ring like that, which is kind of related to... Was one in 200,000. Yes. Oh, so, okay, not the opposite.

No, but the prediction for how often do two black holes that big collide, the predictions were almost... were from, like, zero. But I'm saying before you turned it on, you're like, we're going to hear a signal. Not necessarily from two black holes. The predictions were zero to maybe a few per year.

Meaning that was our range of guessing. It literally could have been zero. But it wasn't, and so your predictions were wrong. Well, it's helping. Now we've done real astronomy. You're serious here. Just tell me your predictions were wrong. Yeah, I don't do that kind of theory, man. Oh, now the disclaimer.

Oh, I don't do that. I don't do that. No, honestly, that was saying we have some uncertainty in how stars are forming, how many of them are that big, and how many of them are in galaxies. And so that gives us an uncertainty. And the range of uncertainty was from like zero to 1,000. Oh, and two fits. One in two days fits in there.

Right, right, right. So just before we go to our next break, Nergis, what would you say was the biggest challenge over those years for LEGO? Was it just funding? Was it the engineering? Because you're predicting you're going to detect something with engineering that was not yet invented.

That's got, that takes gonads. I think the biggest... That's the gender neutral. Is it? I don't think so. Yeah, that's totally gender neutral, I think. I've been working on my gender neutral vocabulary. I don't get credit for that. It takes gonads.

All right. Okay, so I think the most different people will give you different answers. The most difficult thing was getting the instruments to be as sensitive as you could make them. And why is that so important? Because there was a huge amount of uncertainty, as Jana said, in the predictions of what was out in the sky, what would we see. So the only thing we really had control over was how good of an instrument can you make.

Because nature gives you what she does, and the better the instrument, the more likely you were to see something on the low end of those predictions. So I think just pushing on to getting better and better sensitivity was one of the hardest things to keep doing. So while physicists get all the attention, where are the

engineers? Of those thousand co-authors on the paper, I would say a good quarter are engineers. And I just want to add, we say, oh, thousand co-authors on the paper, I would say a good quarter are engineers. And I just want to add, you know, we say, oh, they just turned it on and in a couple of days, that's, you know, a little misleading. So the first generation of instruments was built in 2000 and those didn't hear anything. So there was an, LIGO has existed since then. And this is the second generation of machines. So they left this vacuum along the four kilometer long arms, but they replaced the components into a more advanced machine. So

technically this is advanced LIGO. It's a different machine. So they ran it for 15 years. Well, it wasn't quite 15. When did it turn off? So from 2000 to 2010, we ran what was called initial LIGO, the first phase. Okay, so what it means is your detection levels in that 10 years, nothing happened in the universe strong enough for you to detect in those 10 years. That's correct. And the instrument wasn't sensitive enough. It wasn't 10 years of data.

It was 10 years of operating, but probably between two and three years of data collected because we would take long breaks to make improvements to the instrument. Okay. So, okay. So it was turning on advanced LIGO, and you could feel it as I was on the ground at the sites visiting. You could feel that it was going really fast. You could feel it was going really well, that this was a new...

You could tell a lot of people had cut their teeth on the first instrument. And so the second instrument, you just had this sense that it was happening fast. But I want to clarify that all the experimentalists told me don't expect anything until 2018. And they really, the people who are telling me this really believe don't expect anything until 2018. So it was a surprise.

It went on, and it hit. We'll talk about how the detection of gravity waves launches an entire new era of astrophysics. And, of course, it an entire new era of astrophysics. And, of course, it opens a new window on StarTalk.