 If you pluck the string of an electric guitar, it makes no sound, right? It's only when the body of the guitar records the shape of the string and plays it back through an amplifier that you hear sound. Similarly, when let's say two black holes orbit and collide, they ring the three-dimensional drama of space-time. It's like the whole space rings like a drum. I am so thrilled to introduce tonight's event with Jenna Levin discussing her new book, Black Hole Blues and Other Songs from Outer Space. Jenna Levin is a professor of physics and astronomy at Barnard College of Columbia University. She has been awarded a Guggenheim Fellowship and has contributed to an understanding of black holes, the cosmology of extra dimensions, and gravitational waves in the shape of space-time. So, I did want to talk about the discovery. How many people heard on February 11th the announcement of what people touted as the discovery of the century? How many people heard about the announcement? How many people sat wrapped while it was being explained? Okay, same number of people. How many people within about an hour were like, yeah, I don't get it? Okay, that's probably all of you. No, it's not an insult, it's just an incredibly subtle and difficult subject. When the Higgs particle was discovered, how many people heard about the Higgs discovery? You know, it's hard to understand the role the Higgs plays in physics, but it's not hard to understand that a particle was created by smashing two things together. Right, you smash two things together, you make debris, you made a particle. The gravitational wave discovery is so esoteric. Here's how esoteric it is. In 1915, Einstein writes down his general theory of relativity. It's his lifetime accomplishment. That year, Carl Schwarzschild, who's a German infantry soldier, writes him from the front. It's actually the Russian front. I was going to say the Prussian front, but it was a Russian front during World War I and says, I've been reading the Prussian Academy of Sciences between calculating ballistic trajectories, as you do. I've been thinking about solutions to your equations and he wrote down the solution for the existence of black holes. Now, nobody called them black holes at the time, but it initiated a correspondence between Einstein and Schwarzschild and Einstein said to him, the most important topic for me to turn to at this time, isn't this mathematical solution beautiful, but nothing will allow something like that to form. So the most important topic is the existence of gravitational waves and he says to Schwarzschild, I don't really think they exist. So let me tell you what they are. The idea that Einstein comes up with is that space time around a massive object is curved. Now how do I know that? If I were to take like this book and I was to throw it. Was that bad grammar? I speak pretty good English. I write pretty well. I was to throw it. If I threw that book, would it travel a straight line? It would travel a curved path. It's that simple for Einstein. The earth is not pulling on the object. The object is falling freely around the earth. It must be that the space around the earth is curved and it's really intuitive actually if you think about it. And if I threw the book harder, it would take a straighter path but still curved. And if I threw it hard enough, it would actually go into orbit around the earth and it would be a circle. It would be falling all the time but always just clearing the horizon. And so Einstein comes up with this intuition for a curved space time but it takes him a long time to mathematics it. By 1915 he does. Now here's where gravitational waves come in. If I'm to move the earth, those curves must follow the earth, right? The International Space Station is in a circular orbit around the earth. If the earth moves, surely the circle has to move with it. But nothing can travel faster than the speed of light. So the waves in the shape of space time must communicate to the rest of the universe that the earth has moved and relocated. And that the circular orbit of the International Space Station has relocated with the earth. Those very waves are the gravitational waves. Now Einstein told Schwarzschild in 1916 he didn't think that they were real. It's really interesting. And then in 1937 he writes a paper saying, again, he goes back and forth on this for a while. He writes a paper saying, gravitational waves do not exist between acceptance of the publication and press. He sneaks in a different version that says that they do. And it goes on like this for a while. He says, you know, Professor Einstein, you have to be very careful. Your name is going to be on these papers. And he thinks my name is on plenty of wrong papers, you know? He said about himself, when I was a student, I was no Einstein. So this is going on for decades. This is such a subtle esoteric problem. If you felt after 15 minutes of exposure to the announcement of the discovery of the century that you didn't understand it, you shouldn't feel bad, right? So it took Einstein decades to feel secure in the knowledge that gravitational waves were real. By the late 60s, Ray Weiss, who's a dear friend and a beautiful person and works down the street at MIT, was a young professor at MIT. He was just hired and started a gravity research program. And they asked him to teach a class in this complex subject of general relativity. And he tells me what I knew about general relativity, you could stick in this finger, you know? But he says, yes. Because, you know, he has this whole gravity program. He can't say I don't understand general relativity. And he describes that he was bumbling. He says, I was bumbling, but the students didn't walk out. Because the whole while he was trying to imagine, how would you measure space-time? How would I understand this in a visceral way, in a physical way? And he dreams of this experiment. Let's say the sun blew up. And waves in the shape of space-time traveled eight minutes to get to the Earth to tell us that the sun wasn't where it used to be and that our orbit needs to adjust on the curves in space-time. And he imagines, what if I hung mirrors that would bob on the wave as it passed? And I shine, you know, I put a laser between them. And the laser would keep track of the location of the mirrors. And it would tell me if the mirrors were bobbing on the wave. This is much like something bobbing on the ocean. And he called it a haiku. It turns out there aren't clocks precise enough to do that. So he went one step further. He said, imagine I made an L-shaped instrument so that mirrors at the ends of the L bobbed in the wave. And I put the laser shining between the mirrors. When the laser recombined back at the apex, if the mirrors didn't move, it would recombine perfectly. If the mirrors oscillated on the wave, like things floating on the ocean, it would recombine imperfectly and you could measure that. And he called it a haiku. He said you would think nothing would come of it. He started to build an instrument that was one and a half meters long in the plywood palace. Do you all know about the plywood palace? This is part of your local history. The plywood palace, otherwise known as Building 20, was a shoddy structure thrown up on the MIT campus during the war effort. It was meant to encourage research and radar and microwave engineering. And it was meant to be up for ten years at most and torn down. It was a crappy structure that inspired its inhabitants to violate it liberally. And they were so inspired by being able to punch holes through walls and tap things from the pipes and puncture holes through the ceiling that nine Nobel Prizes came out of the plywood palace. Possibly a tenth with this discovery. And Ray started to build his one and a half meter little machine in the plywood palace dreaming of the sun blowing up and oscillating the mirrors. And one of his colleagues said, literally said, I do better looking out the window. And it was true. He realized he couldn't detect anything from the sun blowing up. And that's because gravity is incredibly weak. You know, the whole earth is pulling on me and I have no problem like resisting the earth. That's crazy. Gravity is phenomenally weak. And at this time, early 70s, people didn't even know black holes were real, let alone that gravitational waves were real, right? So what could possibly cause space time to ring energetically enough that it would be detectable? And people weren't sure there was anything. So Ray tries to get some money for his little machine and it's turned down by the National Science Foundation. And he finds out that people in Germany have heard about his idea and are building a better version and it's bigger and it's technologically more sophisticated and they're great scientists and they're great engineers. And he's got nothing. He's got no money. He has no backing from MIT, no offense MIT. Now he is backing from MIT, trust me. And he thinks to himself, I'm going to miss out. Now I have to tell you there's something else about the machine and that is that it is not like a telescope. If you think about everything we know about astronomy, we really know about things that come to us from light. We take pictures of the sky, right? The Hubble pictures, pictures in all these different wave bands. We have this kind of silent movie of the universe. It traces back 14 billion years. It's 92 billion years across, light years, sorry, rather across. But it's a silent movie. Gravitational waves are not light. It's like a ringing drum of space time itself. I likened the instrument ray dreamt up to an electric guitar. How many people play electric guitar? More of you play electric guitar. I know that you just don't want to admit it. If you pluck the string of an electric guitar, it makes no sound, right? It's only when the body of the guitar records the shape of the string and plays it back through an amplifier that you hear sound. Similarly, when let's say two black holes orbit and collide, they ring the three-dimensional drum of space time. It's like the whole space rings like a drum. And LIGO is like the body of the musical instrument. It records the ringing shape of the drum by these mirrors. And it plays it back through conventional amplifiers. The experimentalists literally listen to the detector in the control room. They listen to it. So this is not a telescope. It's different. It's like a recording. It's a recording of the sounds from space. So Ray's at this point where he says to me, you know, when I was a kid, I had one ambition in life and it was to make music easier to hear. It was to make a better circuit for FM systems so people could listen to the Philharmonic in my living room. And he had this dream of this crazy cosmic recording device to record the sounds of space. This was very integrated in who he was. And he said, I was about to lose out. I had no funding. I did not have the support of my colleagues. And he says to me, the next big event was I met Kip. So Kip Thorne is an iconic astrophysicist who at the age of 30 was already a professor at Caltech and super accomplished. And I feel like Kip dreamt of something bigger even than himself. And they began this campaign. Now we're going to fast forward 50 years. Everyone thinks that on February 11th when they heard the announcement, these people just turned on the machine and it succeeded. Ray is in his 80s. He is still walking the tubes, you know, looking for wasps. It turns out urine from the wasps corrodes the steel, stainless steel. Causes punctures and the vacuums. You know, he's there all the time. He's working on experiments. I cannot tell you how many times people have said to me, we better ask Ray, you know what's going on. So Ray says to me in August 2015, the advanced instrument has just been completely installed. Machines are locked. They know they've reached this experimentally remarkable achievement. The instrument is not one and a half meters. It's four kilometers long. Because as they said, with one and a half meters, you'd do better looking out the window. So they made the machine four kilometers long. There's two instruments, one on a remote site in Louisiana. It's not as remote as one would like because they're logging forests out there and that's not so good, but they've compensated for it and to their advantage actually. And there's another instrument in Hanford, Washington. Each one spans four kilometers. And it's a billion dollars later and now instead of just Ray and Kip and another person around Driever, who's a Scottish physicist who joined the team, there's a team of 1,000 people around the world who work on this committedly. And Ray says to me in August, if we don't discover black holes, this thing is a failure. Which was part of the inspiration for the title, Black Hole Blues. I was like, oh, there's my title. And people told me to be 2018 before there's a discovery. 2018, 2020. And instead in September, September 13th, 2015, they turned the instruments on, which just means that they're locked, which is no mean feat. It's not like flicking a switch. It's a big operation to get the laser locked so that it's really hitting the mirrors and everything's where it's supposed to be. But they decide that they're not ready yet. So they postpone the science runs. They're not ready yet. They're not in any big hurry. Before they make a discovery, after all. They're not in any big hurry. So they're interrupting the machine. Ray says, on Sunday night I was there looking for radio interference. Luckily, my wife told me I had to come home. So he gets on a plane and he goes back to Maine. Graduate students and scientists are working hard on the instrument. They're interrupting it. They're banging on it. It's constantly falling out of lock and they're purposefully doing this. And by four in the morning, Louisiana time two in the morning, Washington State, everybody just decides they're exhausted. They put down their tools. They go home. Within the span of an hour, the gravitational wave from the collision of two black holes, 1.3 billion years ago, was emitted at the time that multi-celled organisms were fossilizing on the Earth. Came from the southern sky, hitting a nearby navial at the time Einstein was born and sort of reveling about the notions of space-time. Hitting the outer solar system in the hours that Ray was disturbing the machine looking offline, looking for radio interference. Eventually rings at about 4.50 a.m. the machine in Louisiana and is recorded. Seven milliseconds later, skimming across the continent, it rings the machine in hand for Washington and is recorded. By the time Ray wakes up, eight something a.m. east coast time, it's billions of kilometers away. But he looks at the logs and he thinks, what the hell is that? He sees in the logs a signal candidate event. And it was the first human-procured recording of any sound from space. I liken it to a sound, not just because this is a recording device, but because if you were floating nearby those two black holes, your ear could technically ring in response. You literally could hear it ring. I mean, I'm not swearing to this because it's not an experiment I'm willing to perform. But if you were nearby the two colliding black holes, it's conceivable that your eardrum would ring in response and you would literally hear it. So it's very close to a sound. So it's the first human-procured recording from the sounds of space. And it was the collision of two black holes 1.3 billion years ago. One of them was 29 times the mass of the sun. One of them was about 35 times the mass of the sun. When they collided, we only saw the final one-fifth of a second. I shouldn't say saw. Recorded the final one-fifth of a second. It was too quiet before that final moment. So it's like mallets on a drum banging on space-time and not until they're going near the speed of light, each one a couple hundred kilometers across, and they collide. Was it loud enough that even for these remarkably sensitive instruments to record, it settled down and went quiet as a black hole about 62 times the mass of the sun. It was the single most energetic event we've ever recorded since the Big Bang. The power that came out in complete darkness in the gravitational waves exceeds the power of all the stars shining in the observable universe combined. It was absolutely not only a remarkable technological achievement, but it's the first time we've ever been able to record something utterly dark. It's the first time we've ever recorded two black holes colliding. And if you heard the news a couple of weeks ago, they announced another event that they heard on Boxing Day on December 26th. So I would actually just like to like have a moment of respect for the experiment. I'll give them a little applause. Yes. So I should clarify that I'm not actually in the experiment. I'm a theoretical physicist. I did get my degree from MIT, but I was working on more particle physics sort of things. And I'm not in the experiment. I'm not an experimentalist. I've been known to ruin boiling water more than once. And I'm rarely allowed into a lab. I was very grateful they let me anywhere near the instrument at all. So what happened in my path to writing this book was very much kind of a moment of admiration for the physicality of the experiment. My work is very pen on paper and it's very mathematical. And I truly believe in what we're doing. But it seemed like something else entirely to build something, right? It's a whole other level of commitment and a whole other level of sort of intensity of belief in the idea. And I just became very enamored of the experimentalists and their accomplishment. And so the book really tracks, it's like a climbing Mount Everest story. When I wrote the book, we didn't know if they would succeed. And I do have an epilogue about the actual detection. But I love that the book was written without the knowledge of the success because I think it really conveys the sort of intensity and insanity that's involved with a scientific endeavor like this. And I think it really epitomizes Ray's statement, you know, if we don't detect black holes, this thing is a failure. That's quite a thing to say at 83 after you've been doing this for 50 years. But it's an honest thing to say. So thank you very much and I'm happy to take questions at this point. The universe is 14 billion years old but how do we know that it translates to 92 billion light years across? That's because the universe is expanding at a particular rate over the history of the universe that we can track. It's expanding at a certain rate in the early history and that the expansion of the universe has accelerated, has picked up pace over the past little while. Like right now, we know that the universe is actually getting faster and faster in its expansion and that's the confirmation of the existence of dark matter. So we have to calculate it. It's not a simple equation. It's not like it is in flat space, I simply say if it's been 10 billion years, light has traveled 10 billion light years. But in an expanding universe, the expansion of the universe makes that bigger. So even though the universe is only 14 billion years old, it's bigger than 14 billion light years in each direction, which would be 28. It's actually 92 if you do the formal calculation. I mean 92 might not be exactly right. I mean the numbers change as we understand dark energy better. Would it be more fair to say that the observable universe has a diameter of 92 billion years? Absolutely. It would be more accurate to say the observable universe has a diameter of 92 billion light years because if you read my first book, How the Universe Got Its Spots, it's on the question of whether or not the universe is infinite or finite. All we know is the light travel time and the light travel distance. We don't know if the universe extends beyond that infinitely and in fact even in the observable universe we're not 100% sure the light hasn't made more than one trip around. So if you imagine you're here in Cambridge and you were to walk in a straight line and just never turn left or right, never slow down, you would eventually come back exactly where you're standing. It's possible that the universe itself is finite and connected in a funny way so that the light has traveled more than once around. But it's very unlikely. If we look at the universe, we cannot see any evidence on the large scale when we look for it and we take it seriously. We can't see any evidence that the light has wrapped around more than once but we do take seriously the idea that there are extra dimensions beyond north, south, east, west, up and down and that those dimensions are curled up very small and so it might be that when the universe is born it's born democratically with like ten spatial dimensions all of which are wrapped up but for some peculiar reason only three become large and so this is one of the intriguing questions why would six stay tightly small and three become large? Although even as we speak there's no observational data that says there's more than three spatial dimensions. Well, I have a theory that dark energy could come from the extra spatial dimensions so maybe dark energy is an observation of extra spatial dimensions or maybe I'm wrong. Those are both very valid possibilities. But you know I'm not attached to these theories like if it's wrong it's wrong. We're just grasping at straws at this stage. Second part of the question was, analogies are great, vital to understand things but this is one scientific experiment if you will that did receive light publicity. We reported these on a cable news guy. Yeah, it was amazing. I did Al Jazeera. Yeah, so the thing is, is it fair to say and I just want to know if I'm right or wrong is that I think that right now in this country you have millions of, let's say, lame and catwalkers walking around thinking, oh, scientists actually recorded sound where in fact it's no more sound than if you plug in headphones into a radio telescope. Oh, it is more sound than that. Yes, and I'll tell you I understand what you're saying. So if I can translate. So the Cassini mission which went by Saturn's rings and things like this recorded electromagnetic radiation which is a form of light in the radio band and simply opted to translate it into sound which you can do all the time. It's just like a cool thing you can do with filters. This is technically different in the following sense. If you were floating near the black holes and they were colliding you have to put yourself at an optimal distance. They actually ring space-time in the human auditory range. Your eardrum as a mechanism, at least it's conceivable. I haven't studied the anatomy in detail but at least it's conceivable would ring in response. Even in the absence of air you would hear the black holes. You wouldn't see them. Your eye is not a detector of gravitational waves. You would technically hear them at least conceivably. It's hypothetically possible. And so in that sense it's much closer to sound. It's much more like the electric guitar. So if I unplug an electric guitar and I play it there's some sense in which you know what I mean when I say it's making a sound. Even though I have to plug it into the amplifier to finalize it. So I do think it's much deeper than a crude sonification of data. But I've read somewhere that Stephen Hawking said that the mathematics of the black hole looks like you get it by understanding that it's a two-dimensional thing that is then projected with three dimensions. And that sounds like the black hole that the universe is a whole of it. Yeah, this is really due to Lenny Susskin and Gerard Asift. Yeah. Are you asking if that's true? Yes. The universe really has the possibility of being a whole of it because the mathematics is the two dimensions. It's very, very important stuff is what I can say now and it's clearly the case. It's a really deep stuff. The idea is this, that the event horizon of the black hole which is the region beyond which light cannot escape which is the shadow of the black hole that that area measures the amount of information that can be stored in it. Not the volume, okay? The amount of information you can store and this is due to technical reasons goes like the area, not the volume. So the argument is if you can encode everything on the area that's a lot like what a hologram does. A hologram takes the information and puts it on a surface but it looks very three-dimensional. So in our reality we think there's more information in three dimensions that you just don't capture in the hologram. You know, I've got an inside, I've got a heart and guts and this kind of stuff. But in black hole theory you can prove you cannot have more information in the volume that you can encode in the area which makes it sound very much like a real hologram as though nature forbids more information than can be encoded in the hologram. And that's due to again Gerard Atouft who is a Nobel Prize winning physicist and Lenny Susskind. He's an absolutely incredibly fascinating visionary guy. As far as we can tell, that may well be true but this is really forefront stuff that's in hot debate and it's not resolved. There's a lot of other reasons to plead that the universe is a hologram that you know stated wrongly and publicly then. Well we'd like to be able to do the same thing in cosmology. We'd like to be able to say that if I look out at the universe and I see that it's expanding which is what was sort of brought up earlier that all of the information in the entire volume of space can be encoded on the surface of this observable. Similar kinds of arguments. It hasn't been effectively translated to cosmology yet. That is something that everyone would like to do but have not done yet successfully. How did they know it was 1.3 billion years ago and it was two black holes? Plus or minus a couple hundred million years and you know, give or take a look. If you imagine hearing your iPhone you know the ringtone so well that you can tell if it's far away, right? And similarly we know we can predict incredibly well and this took decades of hard work on the theorists' behalf. Decades of hard work to be able to model the ringtone which actually you can get on mygo.org for your phone. So that we, you know, when they first got the recording it looked a lot like black hole collision but it took them time to analyze and get the masses right and fit it. So basically what you're fitting is sort of the note that's being played depends on the masses. How loud it is depends on the masses and the distance and you can fit these things to tell if it's two black holes that are 10 solar masses each and closer or 30 solar masses and farther and you can fit it within a certain error and we don't know the distance to better than a few hundred million years. We don't but, you know, that's not bad. We don't care so much about the distance and we might later as we get further along because it'll mean we're hearing them further in the past if they're further away and that might be relevant for us understanding the systems but it's a pretty easy thing to lock in after several decades of hard work. Are the speeds of the collision always the same when black holes are moving in space? And if not, then how do you determine their mass if the rings of different masses shoot? Yeah, the speed. So the black hole mass determines the size. So these black holes were a couple of hundred kilometers across which is pretty small, right? And they're nearly, they're roughly 30 times the mass of the sun but they fit into a couple hundred kilometers, you know, seriously intense objects. And so that means that you can tell how fast they're going around each other because they're really close together. If you had much, much bigger black holes in some sense they'd be going slower and they'd be further apart. So you can tell both how fast they're going and how far, how many orbits they take. That also helps you determine their sizes, right? So if you think about it, sorry? Yeah, because basically it's like mallets on a drum. It sort of oscillates once every full, it oscillates actually twice every full circle. So it tells us how fast they're orbiting which tells us how close together they are which tells us how small they are, right? And that tells us their masses. So the question, more abstract question is can I reconstruct the motion size of the mallets from the sound I hear of the ringing drum? And the answer is yes. Now there are some things we can't tell very well but the masses in the distance we can tell pretty well. They're also spinning and that's harder to determine. What would be needed to visualize a very visual wave? So you would rather visualize it than hear it. What? If you, do you have a stereo system? Do you ever see the wave like if they play the bass? You know how they do? That's the same thing, okay? So if you look at the data in a picture it looks like what you would look at if you're looking at garage band and you're turning down the bass. It's exactly what it looks like. It's like a wave and if it's loud it's got high amplitude and if it's high frequency, high notes it's oscillating faster and if it's low notes it's oscillating slower and that's exactly what it looks like. When they first told me about the detection they showed me a picture. They didn't play me the sound, right? And they showed me a picture which is exactly what you would look at in garage band at the bass. And what was amazing was not only did you see the black holes collide which was meaning they got louder and higher frequency, higher notes. That's why it's a chirp. It goes whoop and it scoops up because they're getting faster and closer together. It increases the frequency just like two mallets on a drum. And then you see them ring down to one black hole which is stunning. You see them collide and it makes this blobby thing which then sheds away its imperfections and becomes a flawless black hole. Black holes are not like anything else in the universe. They're more like fundamental particles and the black hole that settles down after the collision is perfectly flawless and it goes quiet. And you can actually see all of this in the waveform. It's pretty crazy. What do you think of Tegmark's mathematical and universe hypothesis? Sorry, Tegmark's? Max Tegmark's? Is Max here? Max is a fan of mine. I think when Max says something like... So Max Tegmark is a professor from MIT and a colleague and a friend and he says things like objects are mathematical. What do I mean by the electron? I mean a list of its mathematical properties. That's what I mean by the electron. I would agree with that. Absolutely. I don't know what else I would mean. So the electron is also a fundamental particle. It has a specific mass, a specific spin, a specific charge. There are no two electrons that are even slightly different. They're absolutely identical. This is also true about black holes. You cannot say that about anything else in the universe. You can't say that about a star. You can't say that about a book. You can't say that about two copies of my book that they are identical. But two black holes with the same mass, charge and spin are absolutely indistinguishable. It doesn't matter if you made them out of copies of the encyclopedia Britannica, or if you made them out of rhinoceri. Is that the right plural? I don't know why that came out. Who knows how the mind works. You absolutely could not tell the difference. Or antimatter for that. So in that sense, they're closer to electrons on the artist stars. Speak a little bit to what is next. With LIGO? So amazingly, not only did LIGO detect a gravitational wave before 2018, it detected black holes, which everyone told me would be last. So what's next for LIGO is to do old fashioned astronomy like we do with any other telescope. So we're starting to understand the black holes were bigger than we expected. And we're going to try to figure out why that is. There are more of them than we expected. Of the three notable events in the first science run, they all appear as far as we can tell from the whole collisions. We've heard nothing else. So not only are they the first, they seem to be all that we're detecting. Now that might just be that LIGO is working better in low notes. And as the experiment improves in the higher notes, we'll start to hear neutron stars collide, which are dead stars that didn't quite become black holes. We might hear neutron stars with little mountains on them, making monotones as they sort of paddle spacetime. We might hear stars explode. We might hear something we've never imagined before, but I hope, I would hope that we're going to detect something that we have no idea what it is. And that's every scientist's real naughty little hope, right? Like when they discovered the Higgs, people were like, yay, we did it. And they were like, oh, is that it? So it's sort of the same thing with LIGO. We really want to, you know, when Galileo pointed a telescope at Saturn, he did not foresee quasars and galaxies colliding. And so that's what we hope. It'll open up the universe for us. Less than 5% of what we know about the universe is luminous. The rest of it's dark. So the aspiration is that maybe we're going to record this soundtrack to this silent movie that we've mapped. How did you negotiate being there as a writer versus being a professional? That's a really good question. I started out writing a book about black holes, which is my bread and butter. I teach black holes all the time. I researched black holes. I've written many papers about them. I literally, I gave a TED talk in 2011 and when I came off the stage, somebody said to me, I heard you writing a book about black holes and I was like, it's my agent here. Sure enough, you know, he was already hawking the book and I thought, alright, I could do that in my sleep. Instead, I ended up doing something really different, a much more narrative book where these guys are like characters in a way to redirect. It's a lot like science. You set out with a certain hypothesis and then you have to realize that there's something more interesting in the other direction and it was really painful for me. It's why my book was two years late and it was also why it was perfectly timed with a discovery. So had I not been two years late, you all wouldn't be here. And it was hard because I have a long-term relationship with women and I didn't want to suddenly become the writer and not the scientist. And all I can say is that was difficult but the LIGO team has been very good to me and very generous and spent time taking me around the sites and you know, it's a long-term relationship to cultivate. I've cultivated that relationship for a very, very long time and I'm just relieved nobody stabbed me in the eye. I think that's a perfect note to end on. Thank you. GE being the green company it is, I think there's an opportunity for them to do something really creative and visionary here. Perhaps set an example for what the rest of the Boston Waterfront could be doing. Presumably their lawyers have checked the maps and know where they're going to locate.