The Road to LIGO
Last month, scientists at LIGO (the Laser Interferometer Gravitational-Wave Observatory) announced that they’d finally detected gravitational waves. The long-sought signal—which the world heard as a sonified “chirp”—represented the final moments of a cataclysmic collision: two black holes careening into each other and rippling the very fabric of spacetime. The detection required a billion dollars and more than a thousand scientific collaborators.
But as astrophysicist Janna Levin recounts in her new history of the LIGO project, Black Hole Blues and Other Songs from Outer Space, that isn’t the half of it. Over its 50-year-plus history, LIGO was threatened by personality clashes, management missteps, and the sheer scope and difficulty of the project itself. Levin joins Ira to talk about some of the scientists who shepherded LIGO on its long journey from thought experiment to reality.
Janna Levin is author of Black Hole Blues and Other Songs from Outer Space (Knopf, 2016) and a physics and astronomy professor at Barnard College in New York, New York.
IRA FLATOW: This is Science Friday. I’m Ira Flatow. Last month the science world was transfixed by a chirp. Remember that?
That little sound represents a big astronomical event. Two black holes slamming into one another 1.3 billion years ago. And the crash was so cataclysmic it rippled the fabric of spacetime. And it said scientists at LIGO, the signal that they had been waiting for– well, thinking about it for 50 years. The very first direct evidence of gravity waves.
So why did it take so long to get that sound? By the numbers, as I say, it took over 50 years, a billion dollars, over 1,000 scientists. But my next guest will tell you that ain’t the half of it.
Janna Levin is a Professor of Physics and Astronomy At Barnard College here in New York. Her new book, Black Hole Blues and Other Songs from Outer Space, tells the story of LIGO, one of the biggest physics experiments ever attempted. It is a tale of clashing egos, false starts, big machines, and teeny tiny signals. She joins me here in our New York studios to talk about it. Welcome back to Science Friday.
JANNA LEVIN: Thanks Ira, always good to be here.
IRA FLATOW: You know, it’s sort of a– the book is like, it’s entitled Black Hole Blues, but it’s really about gravity waves.
JANNA LEVIN: Yeah. Well, the title was really inspired by one of the original architects, Ray Weiss. He said to me in August just before this first detection was made, if we don’t detect black holes the whole thing is a failure. This is after he’s devoted 50 years to the experiment. And I thought that was such a bold statement to say that before the experiment had succeeded. So I thought about this Black Hole Blues being this long campaign and they still hadn’t succeeded. At least at that time.
IRA FLATOW: But you were there at the right time last fall. Was that by accident? Tell us what happened.
JANNA LEVIN: So what happened is I was two years late on a book. And I set out to write a very different book. I wanted to write a book about black holes, which I know very well that’s my bread and butter scientific research. And so I thought, oh, it’ll be a breeze. I’ll write it overnight.
But instead I got caught up in this LIGO story, which is an experiment that was really beyond my skill set. I mean, I don’t build things. I just do pen and paper and imagine.
IRA FLATOW: You’re a theorist.
JANNA LEVIN: I am a sad little theorist.
IRA FLATOW: You never get your hands dirty.
JANNA LEVIN: No. I mean, Ray once let me do an experiment with him, but it was kind of like how you might let a child. And I just became completely enamored of the ambition and the insanity of it.
IRA FLATOW: And so you– but they made the discovery while you were writing, finishing up the book.
JANNA LEVIN: Right. So I was hanging out a lot of the sites and hanging out the experimentalists a lot. And so when they had installed the advanced components of this machine and they were ready to start taking data, I sort of figured time to wrap up. And funnily enough, on the day that the detection was made, I printed a draft for Kip Thorne and Ray Weiss, two of the original architects. So they didn’t tell me though right away they let me sit and–
IRA FLATOW: Did they give a hint at all? Don’t publish it right now. Something big is going to happen.
JANNA LEVIN: There was sort– Ray was sort of like, what are you going to do if there’s a discovery? But they did take pity on me and tell me early. As soon as they were sure, which was very, very kind of them.
IRA FLATOW: How much of this was luck that they heard it? At that–
JANNA LEVIN: We’ll a lot of the experimentalists told me 2018. A lot, I would say everybody, told me 2018 would be the first detections. So they knew that the advanced machine was doing well, but I don’t think they anticipated– it’s really not at its full capability. I think they expected to have to have spent a couple of years beating the instrument down and making it more sensitive. Instead, during an engineering run, they weren’t even doing science runs.
They were still hammering at the machine, interrupting the data. People were there until the wee hours of the morning the morning that the signal hit from 1.3 billion years ago. And they were interrupting machines. Luckily, everyone puts down their tools, decides they’re too tired, and goes home.
IRA FLATOW: Yeah. Well you were almost– I’m reading the book. I’m seeing you’re like a prophet. You predict almost exactly, and you didn’t know this because it happened yet, exactly what was going to happen. And I have a little passage I’m going to ask you to read where you imagine the kind of signals LIGO might detect. Please, if you will.
JANNA LEVIN: Thank you. OK. So this is some way, midway through the book.
There must be black holes out there that we can never see. They are alone or they orbit another black hole. Nothing falls into them, nothing shines bright enough, close enough. We cannot make out the shadow, at least not yet. But if the black holes collide, we might hear them ring space and time, sending waves in the curves of space time through the universe traveling at the speed of light.
If the gravitational observatories succeed, and we just marginally make out the reverberations against the noise, we can record the sounds of stars exploding and their final seconds before collapse. We can record the sound of imperfections scraping spacetime as neutron stars spin. We can record the sounds of neutron stars colliding, possibly forming black holes. And we can record the sounds of black holes colliding to form heavier silent black holes, emitting a billion, trillion, trillion, trillion watts of power in gravitational waves.
And I should say that those aren’t my predictions. Kip Thorne has been predicting the signals since the late ’70s. And many– the entire theoretical scientific community threw themselves. I mean, not the entire community but those interest in gravitational waves, at predicting these sounds.
IRA FLATOW: And you actually expose the dark side of science research that people never get to see. Dark, literally in crawling through tunnels with spiders and rats. And also the clashing egos and personalities of the scientists.
JANNA LEVIN: Yeah. It is a climbing Mount Everest story. There are bodies left along the side of the road. It’s not all the glory of the announcement. It was a hard campaign and it did literally take 50 years. And there were times when the experiment was really under threat of not actually being built and succeeding.
So I didn’t want to tell that story though. I have to tell you the truth. I thin that’s why the book was two years late. I dreaded getting into all of that and I just had to admit that was a story I was really writing.
IRA FLATOW: And it is. But it’s fascinating. It’s because we don’t really think about science. I mean, I don’t think my audience– we’re a little more fluent in science. But we don’t really talk much about the personalities. That there are real personalities involved. You think, oh, a musician is they’re a little this way. Artists are a little this way. Scientists are the same way.
JANNA LEVIN: Yeah. The experiment would not have been built with if it were not for the individuals involved. It just wouldn’t have been accomplished.
IRA FLATOW: Let’s talk about the difference. So your main character are Ray Weiss, Kip Thorne, and Ron Drever. Tell us about their three different personalities.
JANNA LEVIN: Well, Ray I spent a lot of time with, recorded a lot of tape. And it was actually talking to Ray that convinced me that the book could kind of have this character driven tone. Ray’s just this amazing, direct, straight-talking kind of guy. He’s a no nonsense kind of scientist and he just tells the truth.
I remember there are parts of the book that he didn’t necessarily want to read. But he was like, all right. It’s true. You can keep it. You know? There was no sense of rewriting the past. Very straight-talking guy.
So ray has this beautiful line where he says to me, I started life with one ambition. I wanted to make music easier to hear. And he describes building these circuits to make music easier to hear. And then much later he becomes obsessed with this idea. He could record the sounds of spacetime ringing. And that the instrument he’s thinking about, or at least LIGO does now, it spans the same frequency range as the piano, actually. You can– it’s actually in the human auditory range.
So Ray fulfills this ambition in some kind of cosmic and glorious way by pushing through this instrument. And I should say he still works on the instrument. He’s still on the ground, in the tunnels, performing experiments.
IRA FLATOW: And Kip Thorne is one of the– he’s one of the original thinkers on this project.
JANNA LEVIN: Yeah. Kip is a very special person. I remember being very influenced by Kip when I was a young student and hearing him speak. He’s a real dreamer and his work can be very speculative, but it’s also extremely formal and mathematical and precise. And that combination, I think, made him very special. He was famous at 30, professor at Caltech.
And I talked to him about this a lot. I feel like Kip was looking for something bigger than just his own accomplishments. And when Ray and Kip sort of pooled their resources and banded together, they– that was when they could really realize bringing an experiment this big to Caltech. But that was Kip’s initiative. To bring an experimental ambition to detect gravity and gravitational waves to Caltech.
IRA FLATOW: But one of his great talents also, was his ability to soothe the egos, the competing egos and keep people happy.
JANNA LEVIN: Kip is totally unflappable. And he’s just, he’s really a very charming person. I mean, everybody loves Kip.
I had one part in the book that didn’t make it through the edits but there’s a point where I’m sitting at Caltech during a sabbatical. And Kip’s coming by. And people come to visit and I say, oh, I’m waiting for Kip. And everyone goes, oh, Kip. OK, Kip. He’s sort of a legend.
IRA FLATOW: He used to have a ponytail, if I remember. Years and years ago.
JANNA LEVIN: Yeah.
IRA FLATOW: He’s been around for a while.
JANNA LEVIN: He’s a free spirit.
IRA FLATOW: Yeah. And Ron Drever, the third part of the troika.
JANNA LEVIN: So when Kip decides– so Ray has already built this little prototype, which is maybe 3,000 times smaller than the actual machine. In the late ’70s he’s built this at MIT. But it’s just– it’s a tiny little thing. It can’t really compete with a real instrument which hasn’t been built.
And Kip wants to bring this to Caltech. And he decides– and Caltech decides to hire Ron Drever, who’s a Scottish physicist. Who is very ingenious, very clever, considered a very imaginative person. And I think Ray was second on the short list for this position.
So they hired Ron Drever. Ron comes in the early ’80s to Caltech. And he’s a visionary. He thinks in pictures, not in calculations. And he really does impress people that he can kind of see a solution when other people are taking days to do calculations. But he’s also kind of impossible. And doesn’t want to collaborate. And wants to push this through on his own.
And the three are sort of forced to form a coalition, which is nicknamed the troika. And it’s a good and important alliance but, as Ray says, we couldn’t make one decision as a group.
IRA FLATOW: Of course, you can’t do any of this huge project without the money.
JANNA LEVIN: Right.
IRA FLATOW: And that was a large part. Again, getting the National Science Foundation involved. And Congress had to be convinced of spending this money on something.
JANNA LEVIN: Yes. So eventually directors do come in. Robbie Voke. After him, Barry Barish. And they’re crucial in securing the money. And it starts with a couple hundred million dollars, a few hundred million dollars. But that’s really just R&D. And it’s not until 2000, so this is from the late ’60s to 2000, before the first generation of instruments are actually built.
IRA FLATOW: One of the characters in your book that you spent quite a while talking about is a sort of a tragic figure. Joe Weber. Yeah He created his first little detector and was not included in the final team. Tell us what happened there.
JANNA LEVIN: So I think Joe is a tragic figure. And I think he deserves credit now for starting the field. And even before Ray, and Kip, and Ron Drever, there was Joe Weber. And he sort of struck out alone.
People at this time, you have to realize, still didn’t believe black holes were real. So now this is the early ’60s. And people weren’t even sure gravitational waves were real. This was hotly contested. And Joe goes out he builds what’s called a Weber bar. It’s kind of like a tuning fork. If it’s struck by a gravitational wave of space and time as rippling, it will ring at a particular frequency.
And after about 10 years of doing this, more or less on his own, he makes an announcement that he has evidence for gravitational waves. He becomes the most famous scientist–
IRA FLATOW: Celebrated.
JANNA LEVIN: Celebrated. He’s on the covers of magazines. Before you know it, there are Weber bars everywhere, all over the world. And there’s even, not a Weber bar, but one of his machines is put on the moon. And he’s enormously famous.
But then in two years time all of these other detectors returned silence. They hear nothing from the universe. They don’t detect anything. And there’s also a concern that the rate at which his bars are ringing would suggest that the entire galaxy is just consuming itself and would disrupt entirely. So it doesn’t really seem to be hanging together. But Joe spends the next 30 years insisting.
IRA FLATOW: Let me just– but while we have a little break here, I’m talking with Janna Levin. Author of the terrific book, Black Hole Blues and Other Songs from Outer Space, on Science Friday from PRI, Public Radio International.
And so he sort of becomes disgraced, right?
JANNA LEVIN: Yes. It’s very painful.
IRA FLATOW: They make fun of him.
JANNA LEVIN: Yeah.
IRA FLATOW: They get up– he gets up– they get up at meetings and–
JANNA LEVIN: They try to trick him.
IRA FLATOW: Yeah.
JANNA LEVIN: Yeah. They try to trick him with– some people do– with false claims that he corroborates. And then it’s revealed that it was a false claim. It’s a terrible story. All his funding was withdrawn. He eventually supports his own observatory, he says, with his wallet. And he’ll kind of show his wallet for proof.
IRA FLATOW: Yeah.
JANNA LEVIN: But now Joe is going to come back around. I’m sure of it, in terms of in people’s minds. And if you read the LIGO paper that made the big announcement they discus Joe in the opening pages, which I really respect.
IRA FLATOW: Is the troika going to win the Nobel Prize?
JANNA LEVIN: I hope so. I’m going to get into a lot of trouble. I’ve already gotten into trouble.
IRA FLATOW: Is it bad luck?
JANNA LEVIN: Not up to me man, to say who gets the Nobel Prize.
IRA FLATOW: Phone going to ring at 3:00 in the morning? A little–
JANNA LEVIN: I’d be very happy with the troika. Maybe not everyone feels that way.
IRA FLATOW: You write so enthusiastically in this book.
JANNA LEVIN: Thank you.
IRA FLATOW: And you also insert yourself into the narrative. And you refer to everybody in their first name. Did you feel like that’s the level you had to know them? On first name basis?
JANNA LEVIN: Yeah, it’s interesting. I know Kip very well. Kip is a friend. And I got to know Ray very well. And so I know everybody in the book on a first name basis. It seemed awkward to falsely formalize it.
And I did go back and forth, though. I don’t know Ron personally. And Ron’s health isn’t good. And– Ron Drever. And so for a while I did refer to him as Drever, actually. But Kip called me on it. He said he should be Ron, too. And I thought, that’s right. There’s a certain intimacy. And I got to know his brother in communications.
And I think it lends a certain intimacy. Just the fact that I’m on the ground and a scientist involved with them. It’s both the reason I didn’t want to write about them but–
IRA FLATOW: But that’s the reason you got welcomed in.
JANNA LEVIN: That’s right.
IRA FLATOW: Because you’re a theoretical physicist.
JANNA LEVIN: Yes. That right.
IRA FLATOW: We’re going to have you come back and talk about black holes, which I know is your specialty because there’s so much there. And we all love to talk about them. And we want to know where everything goes once it goes into the black hole. Is the whole universe going to get sucked in? What’s going to happen to it?
JANNA LEVIN: I hope you don’t think I have the answer to that one. I’ll speculate.
IRA FLATOW: But that’s the thing, no one knows.
JANNA LEVIN: That’s right. Good speculation.
IRA FLATOW: Good speculation. All right. Thank you. It’s a great book. It’s called, Black Hole Blues and Other Songs from Outer Space. Janna Levin is the author. And it’s coming out right now, right?
JANNA LEVIN: Tuesday.
IRA FLATOW: Tuesday.
JANNA LEVIN: Officially.
IRA FLATOW: Officially Tuesday. We’ll we’re glad we could have you on in advance. It’s a great, great read.
JANNA LEVIN: Thank you so much.
IRA FLATOW: Janna Levin is the Professor of Physics and Astronomy at Barnard. And she is, as I say, author of Black Hole Blues and Other Songs from Outer Space. And we have an excerpt on our website that’s at sciencefriday.com/blackholes.