Latest / Daniel and Kelly’s Extraordinary Universe / Have we seen more or fewer gravitational waves than expected?

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Have we seen more or fewer gravitational waves than expected? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, has the Large Hadron Collider found fewer or
0:12
Speaker 1: more particles than expected?
0:15
Speaker 2: I guess it depends on what people expected. There were
0:18
Speaker 2: some physicists who thought we'd find zero, and some expected
0:21
Speaker 2: hundreds of particles.
0:23
Speaker 1: Hundreds that seems like a lot.
0:27
Speaker 2: Well, you know, in the sixties we had this era
0:29
Speaker 2: called the particle Zoo. Basically every time you turned on
0:32
Speaker 2: the collider you found something new. This time, unfortunately, we've
0:36
Speaker 2: only found the one particle.
0:38
Speaker 1: Why is it so hard to know how many particles
0:42
Speaker 1: you're gonna find? Don't you guys kind of have an
0:44
Speaker 1: idea of what you're doing?
0:46
Speaker 2: You know, research is exploration in the universe is full
0:49
Speaker 2: of surprises.
0:50
Speaker 1: Maybe it should be full of physicists who are also psychics.
0:56
Speaker 2: Maybe if we stuck physicists in the collider, they would
0:58
Speaker 2: turn into psychics.
1:00
Speaker 1: Have you ever tried sticking your head in the beam, Daniel?
1:03
Speaker 1: Did you get any premonitions?
1:05
Speaker 3: No?
1:05
Speaker 2: But if any listeners out there want to volunteer, write
1:08
Speaker 2: to me.
1:09
Speaker 1: There's going to be so many volunteers, the same volunteers
1:12
Speaker 1: who want to go set up the Mars colony.
1:14
Speaker 2: I don't know if getting your brain fried makes you
1:16
Speaker 2: more or less likely to volunteer to go to outer space. Hi,
1:34
Speaker 2: I'm Daniel. I'm a particle physicist and a professor at
1:37
Speaker 2: UC Irvine, and I definitely do not have the authorization
1:40
Speaker 2: to put your brain in the beam.
1:42
Speaker 1: Hi I am Katie. I am not a particle physicist.
1:46
Speaker 1: I am more interested, well not more interested, but more
1:49
Speaker 1: familiar with the animal sides of things. And I've put
1:53
Speaker 1: my head in a few beams and I feel great.
1:57
Speaker 4: Well.
1:57
Speaker 2: I have no comment about how you turned down, perhaps
2:00
Speaker 2: to ask your parents. But on a parent thing note,
2:02
Speaker 2: my wife is a biologist, and I have sometimes come
2:04
Speaker 2: home to discover that she's included our children in her experiments.
2:08
Speaker 1: Ah, the classic sort of using your own child as
2:12
Speaker 1: the labrat.
2:14
Speaker 2: We had to at some point lay down very strict
2:16
Speaker 2: guidelines about how many parents have to say yes before
2:20
Speaker 2: we could take samples from our children.
2:24
Speaker 1: She's doing some tongue scrapings or did she built like
2:27
Speaker 1: a maze for them?
2:29
Speaker 2: No, our children are not the subjects of psychological experiments.
2:32
Speaker 2: It's more like collecting samples to get data. So it's
2:35
Speaker 2: totally passive, and she was not really breaking any moral thresholds.
2:38
Speaker 2: But I did feel like, hey, we should have a
2:40
Speaker 2: conversation before you do any kind of experiments on our children,
2:45
Speaker 2: because you never know.
2:46
Speaker 1: Just ask permission before you do a cheek swap. That's
2:49
Speaker 1: my philosophy.
2:50
Speaker 2: And welcome to the podcast. Daniel and Jorge explain the universe,
2:54
Speaker 2: in which we explore all the sorts of surprises there
2:57
Speaker 2: are out there in the universe, the things we anticip
3:00
Speaker 2: made and the things we do not anticipate, including coming
3:03
Speaker 2: home to our wives experimenting on our children. My guest
3:07
Speaker 2: and normal co host, Jorge can't be with us today,
3:09
Speaker 2: but I'm very pleased to have with us Katie Golden. Katie,
3:12
Speaker 2: thanks very much for joining us again.
3:14
Speaker 1: Yeah, and I have a good idea and maybe should
3:17
Speaker 1: start having kids so that I can experiment on them.
3:21
Speaker 1: This is this is an interesting idea because right now
3:25
Speaker 1: I have a dog, and the only experiments I can
3:27
Speaker 1: do are treat based behavioral studies such as who is
3:32
Speaker 1: a good girl? Are you the good girl?
3:34
Speaker 2: Well, you know, to some extent, every step you make,
3:36
Speaker 2: every decision you make as a parent, you are kind
3:39
Speaker 2: of experimenting on your kids. You're saying, hmm, let me
3:42
Speaker 2: try this parenting technique and see if they grow up
3:45
Speaker 2: to be a serial killer or a Nobel Prize winner
3:47
Speaker 2: or both.
3:48
Speaker 1: It seems like the child is the one putting you
3:51
Speaker 1: in the skinner box, and you are just trying to
3:54
Speaker 1: modify your behavior such that the child is happy well.
3:58
Speaker 2: Like parenting, research is exploration, which means there are always surprises.
4:03
Speaker 2: You know, when we land a rover on Mars and
4:05
Speaker 2: drive around to see what's behind those rocks, we don't
4:08
Speaker 2: know what we're gonna find. When we train our telescopes
4:11
Speaker 2: on distant galaxies, we always find something new. The same
4:15
Speaker 2: is true and we turn on a particle collider trying
4:17
Speaker 2: to smash particles to create new, higher energies than have
4:21
Speaker 2: existed since the early moments of the universe. Research is exploration,
4:26
Speaker 2: which means that there are no guarantees about what you're
4:29
Speaker 2: going to learn. There's always something surprising out there to
4:32
Speaker 2: be discovered, which is one of the joys of research
4:35
Speaker 2: and exploration and also one of its frustrations.
4:39
Speaker 1: I mean, it sounds like your interest in research is
4:42
Speaker 1: maybe the same as your interest in parenting. Like new
4:45
Speaker 1: things happen, Little surprises happen. Sometimes they're great, and sometimes
4:49
Speaker 1: they're very frustrating.
4:51
Speaker 2: I do sometimes feel a sort of love for a
4:53
Speaker 2: really nice result that I spent a lot of time building, Like,
4:57
Speaker 2: oh wow, look at this little paper go out there
4:59
Speaker 2: into the world. I hope it doesn't get crushed.
5:03
Speaker 1: It's just cradling Matt Lab like a little baby.
5:05
Speaker 2: But there are a lot of other real connections between
5:08
Speaker 2: parenting and research, such as mentoring students. Just like every
5:12
Speaker 2: child needs a different kind of parenting, every student also
5:15
Speaker 2: needs a different kind of guidance. Some of them need
5:18
Speaker 2: almost no guidance and some of them need a lot
5:20
Speaker 2: of hand holding. Fortunately I haven't had to do much
5:22
Speaker 2: like actual disciplining when it comes to my students. But
5:26
Speaker 2: you know, it's a relationship for each individual one you.
5:29
Speaker 1: Have to sit in like the knotty corner if you
5:33
Speaker 1: describe a particle as a wave or a wave as
5:35
Speaker 1: a particle.
5:36
Speaker 2: And so when physicists are not at home at making
5:39
Speaker 2: parenting mistakes, we are at work trying to understand the
5:42
Speaker 2: nature of the universe the same way that you are.
5:45
Speaker 2: And for thousands of years, we had basically only one
5:47
Speaker 2: way to gather knowledge about the far flung corners of
5:51
Speaker 2: the universe. That was electromagnetic radiation. Light in all of
5:55
Speaker 2: its different flavors and kinds, from high energy gamma rays
5:59
Speaker 2: to long wavelength radio waves would come to the Earth
6:02
Speaker 2: and tell us what was going on in those other galaxies,
6:05
Speaker 2: the stars burning bright and creating those photons which would
6:08
Speaker 2: travel across the cosmos to us. But of course there
6:11
Speaker 2: are other ways to get information about what's happening in space.
6:15
Speaker 2: Sometimes actual particles made of matter and will fall to
6:18
Speaker 2: the Earth and we will gather them up cosmic rays
6:21
Speaker 2: and neutrinos and all sorts of stuff. But a few
6:24
Speaker 2: years ago, we pioneered a brand new way to listen
6:27
Speaker 2: to the universe to collect information about what's happening, to
6:31
Speaker 2: be able to see and hear kinds of things we
6:34
Speaker 2: had never seen and heard before.
6:36
Speaker 1: Was it a kind of form of intergalactic semaphore?
6:41
Speaker 2: In some sense, it kind of was. A few years
6:44
Speaker 2: ago we made the fantastical reel and develop the technology
6:47
Speaker 2: to be able to listen to gravitational waves to detect
6:51
Speaker 2: these tiny ripples in space itself. Today, on the episode,
6:55
Speaker 2: I want to look back to that time and think
6:57
Speaker 2: about what we expected to hear when we first turned
7:00
Speaker 2: on this new kind of eyeball or earball or whatever.
7:04
Speaker 2: Biological analogy you want to make for new technology.
7:08
Speaker 1: I mean, I'm very interested because I've had ears for
7:11
Speaker 1: pretty much my whole life, and I have never heard
7:15
Speaker 1: gravity before.
7:16
Speaker 2: So well, when the scientists finished building this apparatus, they
7:20
Speaker 2: didn't know what they were going to hear. And so
7:23
Speaker 2: today on the episode, we're going to answer the question
7:30
Speaker 2: have we seen fewer or more gravitational waves than we expected?
7:35
Speaker 1: Now, this is the thing, is that this is my
7:38
Speaker 1: first time learning about what a gravitational wave is, so
7:43
Speaker 1: I had no expectations how many we would see, given
7:48
Speaker 1: that this is my first time hearing about them at all.
7:50
Speaker 2: Well, for me, it's one of those really amazing moments
7:53
Speaker 2: when you create a new channel between the universe and
7:56
Speaker 2: humanity and you allow nature to speak to us when
8:00
Speaker 2: you had to ask a question and get an answer.
8:02
Speaker 2: There are very few moments like that when you really
8:05
Speaker 2: are hearing something from nature and answer to a question,
8:08
Speaker 2: especially in a new channel you've never opened up before,
8:11
Speaker 2: because it creates the possibility for great surprises, because the
8:14
Speaker 2: universe is often very different from the way that we
8:17
Speaker 2: thought it was, and the only way to make those
8:19
Speaker 2: discoveries is to explore it, is to gather this information.
8:23
Speaker 2: So I was wondering what people thought about this sort
8:26
Speaker 2: of history of gravitational waves. Was it a surprise that
8:29
Speaker 2: we saw some Have we seen more than we expected?
8:32
Speaker 2: Are the gravitational waves that we have seen the kind
8:35
Speaker 2: that we expected? Or is there something weird about them?
8:38
Speaker 2: So I went out there into the internet and asked
8:40
Speaker 2: our army of volunteers to give me their uneducated opinion
8:44
Speaker 2: on this question, which helps me understand what you listeners
8:48
Speaker 2: might have in your heads. So thanks very much to
8:50
Speaker 2: all the volunteers. If you'd like to participate for a
8:53
Speaker 2: future episode, please don't be shy. Write to me to
8:56
Speaker 2: questions at Danielandjorge dot com. So before you hear the answers,
9:00
Speaker 2: think to yourself for a moment. Have we seen fewer
9:03
Speaker 2: or more gravitational waves than we expected? Here's what people
9:08
Speaker 2: had to say.
9:08
Speaker 5: Maybe fewer because I know waves and particles, you know,
9:12
Speaker 5: they you know, act like one another. So if there's
9:14
Speaker 5: a gravitational wave, there have to be like a particle.
9:17
Speaker 5: Maybe we've seen a lot of waves but not the particles.
9:19
Speaker 5: Maybe I'm going to say as much as we expected,
9:21
Speaker 5: but we want to see more.
9:23
Speaker 6: I think we've seen more gravitational waves than we expected
9:26
Speaker 6: I remember correctly. I think Ligo detected the first one
9:29
Speaker 6: in twenty seventeen, and as far as I know, there's
9:32
Speaker 6: also been a few detections since then, so I think
9:34
Speaker 6: we've actually been able to discover more than we were expecting.
9:38
Speaker 7: I know that the ligo has been able to detect
9:41
Speaker 7: some gravitational waves, but it's a really hard task. So
9:45
Speaker 7: if it could.
9:46
Speaker 6: Have better detection equipment, I think we would be able
9:51
Speaker 6: to see even more detections.
9:53
Speaker 4: I would say that we have seen more because when
9:57
Speaker 4: we first before we first detected gravitational waves, I don't
10:03
Speaker 4: know if we were even expecting to see any. So
10:06
Speaker 4: since we detected some, I would say more.
10:09
Speaker 7: I'm not sure how many gravitational waves we expected. I
10:12
Speaker 7: think we may have discovered more than we thought we would,
10:17
Speaker 7: but I'm not sure if it's more than what we expected.
10:20
Speaker 1: I have a question, Daniel. Is it pronounced lego or lego?
10:25
Speaker 2: I think it's pronounced ligo, and this also one in
10:29
Speaker 2: Italy called rugo.
10:30
Speaker 1: I see, so I can't say lego, mylego.
10:34
Speaker 2: You can say that all you like, and you can
10:35
Speaker 2: even build your own ligo out of LEGOS, I.
10:38
Speaker 1: Believe what does logos stand for.
10:41
Speaker 2: LEGO stands for laser interferometer gravitational wave observatory where the
10:48
Speaker 2: W there is sort of suppressed. Otherwise it'd be like
10:51
Speaker 2: lig wo.
10:52
Speaker 1: That would be a little bit too like French. I
10:54
Speaker 1: guess sounding.
10:56
Speaker 2: I don't know lig who bro sounds a little somethings
11:01
Speaker 2: to me. Well, we've talked about gravitational waves a couple
11:06
Speaker 2: of times in the podcast, but maybe not everybody is
11:08
Speaker 2: really comfortable with this idea because frankly, it's a pretty
11:11
Speaker 2: weird concept and it's something that Albert Einstein predicted but
11:15
Speaker 2: also predicted we would never ever be able to detect.
11:18
Speaker 2: So it's worth taking a minutes to remind ourselves what
11:21
Speaker 2: are gravitational waves exactly?
11:23
Speaker 1: Yeah, because we're talking about like leg wobro and gravitational waves.
11:27
Speaker 1: Is this something I could surf on? Is this something
11:30
Speaker 1: I could see? Is it something where if I jump
11:33
Speaker 1: during a gravitational wave, I feel myself get pulled down
11:37
Speaker 1: to Earth faster. I'm ready to learn because this is
11:39
Speaker 1: an entirely new concept to me.
11:41
Speaker 2: Gravitational waves are one of the amazing predictions of general
11:45
Speaker 2: relativity and one of the coolest things about them is
11:47
Speaker 2: that they are waves, waves like we see in other things,
11:50
Speaker 2: meaning that they follow the same mathematical formula. It's incredible
11:54
Speaker 2: to me that the same sort of phenomenon appears in sound,
11:58
Speaker 2: and in water and in light, and also in the
12:01
Speaker 2: ripples of space itself. So that's what gravitational waves are.
12:05
Speaker 2: They're like updating information about gravity. They're wiggles in space.
12:10
Speaker 1: That sounds like a kid's program, wiggles in space. I
12:14
Speaker 1: guess I'm trying to wrap my head around the idea
12:16
Speaker 1: of what is a wiggle in space? How does space wiggle?
12:20
Speaker 2: Yeah, before we can answer how to space wiggle, we
12:22
Speaker 2: have to understand a little bit about what it means
12:24
Speaker 2: for space to bend at all, and they will put
12:27
Speaker 2: that together. To understanding wiggles and space bending is the
12:30
Speaker 2: fundamental concept of general relativity. It tells us that the
12:34
Speaker 2: force that we feel of gravity, the reason that you
12:37
Speaker 2: are held to the Earth and the Earth is going
12:39
Speaker 2: around the Sun, is not actually a force at all.
12:41
Speaker 2: It's an apparent force, something we describe as a force
12:45
Speaker 2: because we don't really understand what's going on, and apparent
12:48
Speaker 2: forces are not something weird or magical. We experience them
12:51
Speaker 2: all the time. If you're in a Merry go Round
12:53
Speaker 2: with your friends and somebody spins it, you feel this
12:56
Speaker 2: force outwards. You feel like somebody's trying to throw you
12:58
Speaker 2: off the merry go Round, But there is no force there.
13:01
Speaker 2: Nobody is pushing you outwards. It's just a consequence of
13:04
Speaker 2: the fact that you're spinning. There's this accelerated frame of reference.
13:08
Speaker 2: You want to keep going in the direction that you
13:10
Speaker 2: were going, and that looks to somebody on the Merry
13:13
Speaker 2: go Round as if you're being pushed, you know. Or
13:16
Speaker 2: if you try to throw a ball from one side
13:17
Speaker 2: of the Merry go Round to the other, it wouldn't
13:19
Speaker 2: move in what looks to you like a straight line
13:22
Speaker 2: because the Merry go Round is spinning. That's the concept
13:25
Speaker 2: of an apparent force. It's not a true force. It's
13:28
Speaker 2: something that comes out of the properties of the system
13:30
Speaker 2: that we're in. And so gravity is also an apparent force.
13:35
Speaker 2: Space itself curves, it bends, and when we say space bending,
13:39
Speaker 2: we're talking about the relative distances between two points. So
13:43
Speaker 2: as the Earth, for example, moves through space, the space
13:46
Speaker 2: in front of it is curved, and so it moves
13:49
Speaker 2: through what it seems to be the natural path which
13:52
Speaker 2: follows that curvature. But to us it looks like somebody
13:55
Speaker 2: is bending it because we can't see that curvature of
13:58
Speaker 2: space directly.
13:59
Speaker 1: So I I like jump from the top of the
14:02
Speaker 1: stairs down a few steps. It feels just like I'm falling.
14:06
Speaker 1: It's this normal, you know, I'm falling apart am I
14:09
Speaker 1: just traveling through sort of the path of space that
14:14
Speaker 1: has been created by the gravity of Earth.
14:17
Speaker 2: That's exactly right. Anytime you move according to gravity, you're
14:21
Speaker 2: in free fall. You're just following the curves of space.
14:24
Speaker 2: So for example, you get an airplane, you fly it
14:27
Speaker 2: pretty high, and you throw out a tennis ball. What
14:29
Speaker 2: happens to that tennis ball. Well, Newton would say it's
14:32
Speaker 2: accelerated by the force of gravity towards the center of
14:35
Speaker 2: the Earth. And Einstein would say, no, no, it's just
14:38
Speaker 2: following the curvature of space. It's just moving with space.
14:42
Speaker 1: It's interesting that the curvature of space often like winds
14:46
Speaker 1: up at the pavement and then I hurt myself. But
14:50
Speaker 1: good job, space. Why couldn't you wind up always at
14:53
Speaker 1: a nice soft mattress.
14:55
Speaker 2: And it's really a role reversal because Newton says, oh,
14:58
Speaker 2: that tennis ball is being accelerat, right, it's being pulled
15:01
Speaker 2: down towards the center of the Earth. And Einstein says, no,
15:04
Speaker 2: it's not. It's just free falling with gravity. And in fact,
15:07
Speaker 2: if you have an accelerometer or something which measures whether
15:10
Speaker 2: you're getting pushed or pulled on that tennis ball, then
15:13
Speaker 2: it won't notice any acceleration. It doesn't feel like it's
15:16
Speaker 2: being accelerated, because it's not. The acceleration comes when you
15:20
Speaker 2: splat on the pavement and the pavement accelerates you very
15:23
Speaker 2: rapidly upwards. Right, that's the acceleration. So Einstein reverses that
15:29
Speaker 2: because the.
15:30
Speaker 1: Pavement is just in the way of the way that
15:34
Speaker 1: space is now shaped for you, right, because you're following
15:37
Speaker 1: this sort of path carved out for you by gravity,
15:42
Speaker 1: and it just so happens that the pavement's right there
15:45
Speaker 1: in your way.
15:46
Speaker 2: Einstein says, if you jump off a building, you're not
15:49
Speaker 2: accelerating as you fall. You only accelerate when you hit
15:52
Speaker 2: the ground, accelerate very rapidly and destructively upwards. Newton says
15:57
Speaker 2: that if you jump off a building, yes, you're accelerated
16:00
Speaker 2: down towards the center of the Earth. So it's two
16:02
Speaker 2: very different pictures about how gravity works. And Einstein's picture
16:06
Speaker 2: is beautiful because it tells us that space itself has
16:09
Speaker 2: this feature which was invisible to us until now. Right,
16:12
Speaker 2: we can't see the curvature directly. It's not like a
16:15
Speaker 2: road you're following you can see it curving ahead of you.
16:17
Speaker 2: It's invisible to us, so it looks like there's this weird,
16:21
Speaker 2: mysterious force acting on things and changing their paths, when
16:24
Speaker 2: really things are just naturally following the invisible curvature of space.
16:28
Speaker 1: So before we actually had the abilities to see something
16:33
Speaker 1: like a gravitational wave, how did we know that Einstein
16:36
Speaker 1: was probably right and that Newton was probably wrong.
16:39
Speaker 2: Well, Einstein makes a very different prediction from Newton in
16:42
Speaker 2: some cases. In many cases they're totally exactly the same.
16:46
Speaker 2: But for example, Einstein predicts that photon, that light itself
16:50
Speaker 2: can be bent by gravity. Newton would say, well, photons
16:53
Speaker 2: have no mass, so there's no gravitational effect. But Einstein
16:56
Speaker 2: would say that space is curved and photons follow the curvature,
17:01
Speaker 2: so photons can get bent around heavy things. So he
17:04
Speaker 2: made this prediction for what we would see in eclipse
17:06
Speaker 2: as light got bent around those heavy objects. And he
17:10
Speaker 2: was right and Newton was wrong.
17:12
Speaker 1: So now I understand that space can basically bend, and
17:17
Speaker 1: this gravity is basically this bending of space. I just
17:21
Speaker 1: follow this path of space. So if I think about it,
17:25
Speaker 1: it's like I'm like on a sheet and someone's angling
17:28
Speaker 1: the sheet downwards, and I slide down the sheet. And
17:32
Speaker 1: so if you get a gravity wave, are you just
17:34
Speaker 1: sort of like wiggling that sheet a little bit.
17:37
Speaker 2: It's very tempting to use the sheet analogy, but I
17:39
Speaker 2: find the kind of problematic because the sheet is two dimensional,
17:43
Speaker 2: and now you're sliding down, which implies some sort of
17:46
Speaker 2: gravity in the third dimension. What's really happening is that
17:49
Speaker 2: you're changing the relative distances between things to make one
17:53
Speaker 2: path shorter and one path longer. But you're right that
17:56
Speaker 2: we can put this conception together to understand wiggling, because
17:59
Speaker 2: this the course of that bending is mass. It's not
18:02
Speaker 2: like space is just bent willy nilly here and there.
18:05
Speaker 2: It's bent around mass. So the Sun bends space around it. Now,
18:09
Speaker 2: what happens if you move the Sun You so of
18:12
Speaker 2: shift the Sun over a meter. Well, the bending of
18:14
Speaker 2: space has to follow, right, but that doesn't happen instantaneously.
18:18
Speaker 2: So if you shift the Sun over suddenly by one meter,
18:21
Speaker 2: then the bending of space propagates outwards. It's like a
18:24
Speaker 2: ripple in space. Now do the wiggles where you move
18:27
Speaker 2: the sun one meter to the right and then one
18:29
Speaker 2: meter to the left, and you know, then do the
18:31
Speaker 2: hokey poke and turn it all around. If you're going
18:34
Speaker 2: back and forth, then those ripples are constantly being generated,
18:37
Speaker 2: and what you get are wiggles in space. That's a
18:40
Speaker 2: gravitational wave.
18:42
Speaker 1: So if wiggles in space are caused by the movement
18:46
Speaker 1: of large masses, or I guess it would be caused
18:50
Speaker 1: by any mass size, right, would you just have a
18:53
Speaker 1: smaller wiggle for a smaller mass.
18:55
Speaker 2: Yes. Gravity is super duper weak, and so while everything
18:59
Speaker 2: generates grab vitational waves when it accelerates, only more massive
19:03
Speaker 2: things can generate gravitational waves that we have any chance
19:06
Speaker 2: of detecting, which is one reason why when we started
19:09
Speaker 2: out we looked for gravitational waves from huge black holes
19:13
Speaker 2: spiraling around each other super duper fast.
19:16
Speaker 1: So given that for any kind of like gravitational wave
19:22
Speaker 1: that we would observe, it would have to be from
19:24
Speaker 1: something pretty big, right.
19:26
Speaker 2: It have to be from something really big and not
19:29
Speaker 2: too far away.
19:30
Speaker 1: So given that, I would think that it might be
19:33
Speaker 1: kind of rare, because I don't know how many massive,
19:37
Speaker 1: sort of wiggly bodies are too close to Earth. But
19:41
Speaker 1: you know, so I my guess, now that I understand
19:44
Speaker 1: what a gravity wave is, would be that we would
19:46
Speaker 1: only see them every so often.
19:47
Speaker 2: Well, that was exactly the question they didn't know the
19:50
Speaker 2: answer to. They were building this new technology which could,
19:53
Speaker 2: for the first time listen to these things. What they
19:55
Speaker 2: didn't know was is the universe noisy in this new spectrum?
19:59
Speaker 2: Or is it totally quiet? Is there anything out there
20:02
Speaker 2: to here? They didn't know the answer because we don't
20:05
Speaker 2: understand the astrophysics of black holes. How often are they
20:09
Speaker 2: spiraling into each other and making this sound that we
20:12
Speaker 2: just built a new microphone for? That was the fundamental question.
20:16
Speaker 1: Well, I'm going to say it happens once a month.
20:21
Speaker 1: That's my production as a very very educated person. But
20:26
Speaker 1: when we will take a quick break, I'll do a
20:28
Speaker 1: little back of the envelope math see if I got
20:30
Speaker 1: that right, and then maybe you can tell me how
20:34
Speaker 1: often we've actually seen these gravity waves. So we are back.
20:51
Speaker 1: I drew this very demonstrative tic tac toe on the
20:56
Speaker 1: back of this envelope, and I think it will lead
20:59
Speaker 1: you to some pretty interesting revelations about gravity wells. But
21:04
Speaker 1: maybe I should actually ask the particle physicist how many
21:08
Speaker 1: of these gravitational waves have we actually seen.
21:11
Speaker 2: It's amazing to me that we've seen any You know,
21:13
Speaker 2: Einstein predicted that these things existed, but he was very
21:17
Speaker 2: skeptical that we could ever see them because gravitational waves
21:21
Speaker 2: are so weak. I mean, the effect they have on
21:23
Speaker 2: matter is really really tiny. You take a ruler, for example,
21:27
Speaker 2: and a gravitational wave passing through it would shrink it
21:29
Speaker 2: by one part in ten to the twenty or one
21:32
Speaker 2: part inten to the twenty one, which seemed so impossible
21:36
Speaker 2: to measure, and it took decades before anybody even really tried.
21:41
Speaker 2: We know now about the success of Lego and Virgo
21:43
Speaker 2: in twenty sixteen, but well before that people were thinking
21:47
Speaker 2: about the possibility, and there was some pretty colorful history
21:50
Speaker 2: about early attempts.
21:51
Speaker 1: Yeah, I mean, I can't even wrap my head around
21:54
Speaker 1: how you measure a gravitational wave.
21:56
Speaker 2: So what you're trying to do is see space wiggle
21:59
Speaker 2: back and forth. And so for example, if you have
22:02
Speaker 2: two objects at a fixed distance and a gravitational wave
22:05
Speaker 2: passes through it, what you'll see is those things get
22:07
Speaker 2: slightly closer and then further, and then closer and then further.
22:11
Speaker 2: So if you have some very precise ruler which doesn't
22:14
Speaker 2: shift also with the gravitational waves, right, it's like rigid
22:17
Speaker 2: where it uses laser beams, as we'll talk about later.
22:19
Speaker 2: Then if you could measure their positions super duper precisely
22:23
Speaker 2: and you have a way to avoid them otherwise wiggling,
22:26
Speaker 2: then you can detect gravitational waves. That's the key.
22:29
Speaker 1: Sounds like you need someone with incredibly steady hands.
22:33
Speaker 2: The first person is to take this seriously. It was
22:36
Speaker 2: a guy named Joseph Weber and in the late sixties
22:40
Speaker 2: he built this big rod made of aluminum, these huge
22:43
Speaker 2: aluminum cylinders that could vibrate a resonant frequency. And his
22:47
Speaker 2: idea was that gravitational waves passing through it would cause
22:50
Speaker 2: these things to resonate. And he attached these piezoelectric sensors
22:54
Speaker 2: to them to make them super duper sensitive to tiny,
22:56
Speaker 2: tiny wiggles in these cylinders, and so these are called
23:00
Speaker 2: Weber bars, and he actually made claims of discovering I mean,
23:03
Speaker 2: he saw wiggles in these things, and he thought, I'm
23:06
Speaker 2: seeing gravitational waves. Now, at the time, this was not
23:09
Speaker 2: taken very seriously because nobody thought gravitational waves were observable
23:14
Speaker 2: at all, and so the idea that this guy had
23:17
Speaker 2: seen them was like, very, very outlandish. Another problem was
23:20
Speaker 2: that nobody could reproduce his results. I mean, people were
23:23
Speaker 2: excited about it in principle, and a few other people
23:26
Speaker 2: tried building similar devices to see if they could see
23:29
Speaker 2: what he had seen, But nobody else ever saw the
23:31
Speaker 2: blips that Webber had seen.
23:33
Speaker 1: So this is kind of the equivalent of someone saying, hey,
23:37
Speaker 1: I just held a seance and found a cure for cancer, exactly.
23:40
Speaker 2: I had sort of a polarizing impact on the field
23:43
Speaker 2: of gravitational wave astronomy. It made some people feel like,
23:46
Speaker 2: oh my gosh, this feel is poisoned. It's filled with
23:49
Speaker 2: Charlatan's And you know, there was some really colorful and
23:52
Speaker 2: heated exchanges at conferences. You know, in June nineteen seventy four,
23:57
Speaker 2: this physicist Garwin aggressively confronted did Weber with a claim
24:01
Speaker 2: that they had found a mistake in his computer program
24:04
Speaker 2: that analyzed his data and said that Weber's model was insane, quote,
24:08
Speaker 2: because the universe would convert all of its energy into
24:11
Speaker 2: gravitational radiation in fifty million years or so if one
24:14
Speaker 2: were really detecting what Joe Webber was detecting. So this
24:18
Speaker 2: got pretty hot and heavy, and there were like letters
24:20
Speaker 2: written back and forth and physics today, this is like
24:23
Speaker 2: a real physics feud.
24:25
Speaker 1: I mean, it's very funny from the outside looking in
24:29
Speaker 1: that this kind of you know, very technical thing of
24:33
Speaker 1: detecting gravity waves would cause basically a physics riot, people
24:38
Speaker 1: turning over cars.
24:39
Speaker 2: Well, it was an outlandish claim, right, and so while
24:42
Speaker 2: people are excited to believe it, also scientists are skeptical
24:46
Speaker 2: and they got to be persuaded. And you're going to
24:48
Speaker 2: make a claim like this, it's got to be rock solid.
24:50
Speaker 2: And Weber continued to claim until his death that his
24:54
Speaker 2: gravitational wave discoveries were real. And so, on one hand,
24:58
Speaker 2: nobody believes that he saw grap vietational waves, and he
25:01
Speaker 2: sort of gave the whole field a bad name. On
25:03
Speaker 2: the other hand, he was kind of a pioneer. He
25:06
Speaker 2: had the courage to try something out there, something weird,
25:09
Speaker 2: something crazy, something nobody even thought was possible at all,
25:13
Speaker 2: and in that sense did inspire the next generation of
25:16
Speaker 2: gravitational wave astronomers, who in the end did figure it out.
25:20
Speaker 2: There's a quote from a famous physicist, Wheeler whose Fineman's
25:23
Speaker 2: grad school advisor, and he says, quote, no one else
25:26
Speaker 2: had the courage to look for gravitational waves until Weber
25:29
Speaker 2: showed that it was within the realm of the possible.
25:32
Speaker 2: So you got to give Weber's some props for like
25:34
Speaker 2: cracking this field open, even if his claims of discovery
25:37
Speaker 2: never were born out.
25:39
Speaker 1: It's definitely sort of a situation where nobody wants to
25:42
Speaker 1: be the first idiot to try something, and then once
25:46
Speaker 1: someone is the first idiot, it's like, well, at least
25:49
Speaker 1: I won't be as much of an idiot as that guy,
25:51
Speaker 1: so I get to try it this time. But that
25:54
Speaker 1: first idiot is often very brave, and as long as
25:58
Speaker 1: they don't die doing it by eating the wrong berries,
26:01
Speaker 1: they are I think heroes.
26:03
Speaker 2: Yeah, well, you know, just feed those berries to your
26:05
Speaker 2: dog or your kid or whoever else you're willing to
26:07
Speaker 2: experiment on. So this whole field is facing two big questions.
26:12
Speaker 2: One is is it technically possible to see gravitational waves right, like,
26:18
Speaker 2: can we build a device that can detect these things?
26:20
Speaker 2: And the second is are there any gravitational waves at all?
26:25
Speaker 2: And you know, now we are seeing gravitational waves from
26:27
Speaker 2: black holes. But remember that back in the sixties and seventies,
26:30
Speaker 2: the whole idea of black holes being real was kind
26:34
Speaker 2: of new.
26:35
Speaker 4: You know.
26:35
Speaker 2: Black holes were another prediction of general relativity, which for
26:38
Speaker 2: a long time people thought, nah, that can't actually exist
26:41
Speaker 2: in the universe. It wasn't until we found bright radio
26:44
Speaker 2: sources from the center of the galaxy and saw compact
26:47
Speaker 2: objects we couldn't otherwise explain. The whole idea of black
26:51
Speaker 2: holes went from crazy land to realistic. And so this
26:55
Speaker 2: whole field is facing these two challenges simultaneously. But Weber
26:58
Speaker 2: did inspire a bunch of other folks who had ideas
27:01
Speaker 2: for how to build gravitational wave detectors using lasers. One
27:05
Speaker 2: of the problems with Weber is that his device was
27:07
Speaker 2: just too small. I mean, gravitational waves are super duper weak,
27:11
Speaker 2: and so if you need to see a tiny increase
27:13
Speaker 2: in the length of something, that's easier to do if
27:16
Speaker 2: the something is really really big, bigger than like your
27:19
Speaker 2: basement laboratory. You want something which is like tens of
27:22
Speaker 2: meters or even kilometers long, so the effect of the
27:25
Speaker 2: gravitational wave is larger.
27:27
Speaker 1: I mean, it's sort of the blue whale model of physics,
27:30
Speaker 1: where if your prey is very very tiny, it actually
27:35
Speaker 1: helps to have a really really big net so that
27:38
Speaker 1: you can catch a whole bunch of them. The bigger
27:41
Speaker 1: the mouth, the easier it is to find the tiny
27:43
Speaker 1: things exactly.
27:45
Speaker 2: And so a bunch of folks at Caltech developed these
27:47
Speaker 2: ideas for using lasers. The idea is instead of building
27:52
Speaker 2: like a bar that's a kilometer long, just having use
27:56
Speaker 2: an interferometer, which means you don't have an actual physical device,
27:59
Speaker 2: you know, measuring the distance between two mirrors, for example,
28:03
Speaker 2: by shooting a laser beam back and forth. And essentially
28:06
Speaker 2: what you're doing is you're counting the number of times
28:09
Speaker 2: the laser has wiggled on its journey because light has
28:13
Speaker 2: a certain wavelength, As you actually split the beam and
28:15
Speaker 2: send it in two different directions, and so when those
28:18
Speaker 2: two beams come back, you interfere them and if they wiggle,
28:21
Speaker 2: the different number of wavelengths on their journey, then it
28:25
Speaker 2: changes the pattern of light that comes out in a
28:27
Speaker 2: way that you're very very sensitive to.
28:29
Speaker 1: Oh interesting, So when you split a beam right and
28:33
Speaker 1: neither of them changes when they rejoin, would they sort
28:37
Speaker 1: of go back to the original state that they were
28:40
Speaker 1: in when they had split exactly?
28:42
Speaker 2: If they both take exactly the same length journey, then
28:44
Speaker 2: when they come back, they're the same part of their
28:46
Speaker 2: wiggle and so they add back up to be their
28:48
Speaker 2: original beam. If instead one of them has like gone
28:51
Speaker 2: a half wavelength further, then now it's wiggling down when
28:55
Speaker 2: the other one's wiggling up, and they would cancel out,
28:57
Speaker 2: they would destructively interfere. By seeing that interference pattern, you
29:02
Speaker 2: can tell very precisely how far that photon has traveled.
29:06
Speaker 1: That's really clever. But you got to hold the mirrors
29:08
Speaker 1: like really stable right.
29:10
Speaker 2: Exactly, And that is the whole challenge is stabilizing these
29:14
Speaker 2: mirrors against like a truck driving down the highway or
29:17
Speaker 2: you know, a fly flying by, or seismic noise from.
29:21
Speaker 1: The under underground. I want to go underground.
29:26
Speaker 2: So they developed this prototypic caltech in their early eighties
29:30
Speaker 2: with these laser arms that were like forty meters long.
29:33
Speaker 2: Actually visited this thing when I went to Caltech to
29:35
Speaker 2: think about going to grad school there, and I remember thinking,
29:38
Speaker 2: this is a crazy experiment that's never going to work.
29:42
Speaker 2: And boy was I wrong. I'm very happy to be
29:45
Speaker 2: wrong about it. That experiment improved in principle that you
29:47
Speaker 2: could do this laser interferometry. Though there were all sorts
29:50
Speaker 2: of like crazy cost overruns and all sorts of shenanigans
29:54
Speaker 2: and the sort of how they actually got hundreds of
29:57
Speaker 2: millions of dollars to build legoineteen ninety four. NSF funded
30:02
Speaker 2: it at two hundred and seventy million dollars, this huge,
30:05
Speaker 2: scaled up version of the Caltech project with arms that
30:08
Speaker 2: were kilometers long. It's an amazing story of like the
30:12
Speaker 2: right person at the right time who happened to be
30:14
Speaker 2: really into this despite like crazy cost overruns and mismanagement
30:19
Speaker 2: in the original project. But somehow the NSF did it.
30:22
Speaker 2: It was the biggest project they've ever funded in their history.
30:26
Speaker 1: That person who wrote the grant deserves some kind of
30:30
Speaker 1: award because writing a grant where it's like, now, we
30:33
Speaker 1: don't know if these things exist, and it's very unlikely
30:37
Speaker 1: we would ever be able to detect them. However, money exactly.
30:42
Speaker 2: There's a guy the NSF, Isaacson, who said, quote, it
30:45
Speaker 2: should never have been built. There's a couple of maniacs
30:49
Speaker 2: running around with no signal having ever been discovered, talking
30:52
Speaker 2: about pushing vacuum technology and laser technology and material technology
30:57
Speaker 2: and seismic isolation and feedbacks systems orders of magnitude beyond
31:02
Speaker 2: the current state of the art, using materials that hadn't
31:05
Speaker 2: been invented yet.
31:06
Speaker 1: Grant writers who get their grants like rejected for a
31:09
Speaker 1: reasonable proposal just snapping their pencils in half in rage
31:13
Speaker 1: right now.
31:14
Speaker 2: Yes, exactly, and so what kudos to them? At the time,
31:17
Speaker 2: a lot of astronomers were furious because this was a
31:20
Speaker 2: huge chunk of money which could have gone to other projects,
31:23
Speaker 2: and this seemed like a real boondoggle and if it
31:25
Speaker 2: didn't see anything, it was going to kill the whole field.
31:28
Speaker 2: So it's very controversial decision at the time. You know, now,
31:31
Speaker 2: of course it's one Nobel prizes that were all grateful
31:33
Speaker 2: for it, but at the time it was a really
31:36
Speaker 2: really big risk for the NSF.
31:37
Speaker 1: It's like the saving private Ryan of the physics world.
31:41
Speaker 2: So the first iteration of the experiment LIGO ran from
31:43
Speaker 2: two thousand and two to twenty ten, and they didn't
31:46
Speaker 2: see any gravitational waves. And you know, they could have.
31:49
Speaker 2: They were sensitive to gravitational waves, but they weren't as
31:53
Speaker 2: good at like tamping down the noise and making everything
31:56
Speaker 2: really crisp and clean as the next version of LOGO
31:59
Speaker 2: was the one that actually made the discoveries. So for
32:01
Speaker 2: them to have seen something the gravitational waves would have
32:04
Speaker 2: to be like an elephant stampede. It was really more
32:07
Speaker 2: about the developing the technology than actually discovering anything.
32:10
Speaker 1: Two elephant shaped black holes crashing into each other.
32:15
Speaker 2: So they made that work and it meant a lot
32:16
Speaker 2: of stuff along the way, and then they shut down
32:19
Speaker 2: to build advanced LEGO, which meant like reducing the noise
32:23
Speaker 2: even further, because the quieter you can make the environment
32:26
Speaker 2: for your lasers, the smaller the wiggle you can actually
32:29
Speaker 2: detect and be confident in, which means you can hear
32:31
Speaker 2: fainter signals, which means you can hear signals from further
32:34
Speaker 2: out in the universe, so you're sensitive out to like
32:37
Speaker 2: larger distances.
32:39
Speaker 1: Now, as a podcaster, which is basically the same complexity
32:43
Speaker 1: as being a part of Cull physicist. I always struggled
32:46
Speaker 1: to get the sound quality good. I mean, right now
32:49
Speaker 1: I'm traveling, so I'm actually in a closet trying to
32:53
Speaker 1: reduce the amount of bouncing of audio waves. So how
32:57
Speaker 1: do you do this though with something like this, because
33:01
Speaker 1: you can't just put a bunch of foam around it.
33:04
Speaker 1: We're stuck on earth, Well we're not, but for this
33:07
Speaker 1: we are. And you have all this movement of the earth.
33:12
Speaker 1: How do you and like you can't even going underground,
33:15
Speaker 1: you still have I would assume some seismic movement underground.
33:19
Speaker 1: So what do you do to cancel that out?
33:22
Speaker 2: So they have a lot of different tricks they use.
33:24
Speaker 2: One is that they put it on a pendulum. They
33:26
Speaker 2: basically balance the whole thing on a string, which helps
33:29
Speaker 2: decouple it from the motion of the earth. But then
33:32
Speaker 2: they actually add another pendulum to that one, and another pendulum,
33:35
Speaker 2: so they have like four pendulum stages, so that you
33:38
Speaker 2: can like shove the top of this thing and the
33:40
Speaker 2: mirror itself will hardly move. On top of that, they
33:44
Speaker 2: have like active servos to reduce seismic noise, which is
33:49
Speaker 2: sort of like noise canceling headphones. You know, they detect
33:52
Speaker 2: wiggles in the earth, and then they unwiggle the mirror
33:55
Speaker 2: and sort of to move it the opposite direction to
33:58
Speaker 2: prevent the mirror itself from moving.
34:00
Speaker 1: Now, have they tried plugging in a chicken brain? Because
34:03
Speaker 1: chickens and other birds are really good at stabilizing their heads.
34:09
Speaker 1: You can grab a chicken, buy its body and move
34:11
Speaker 1: it around and its head stays perfectly stable. So it
34:15
Speaker 1: sounds like servos are just basically little robotic chicken brains.
34:19
Speaker 2: Yeah, that's actually the internal name they use in the
34:21
Speaker 2: experiment is robotic chicken head, you know, and that's how
34:24
Speaker 2: they referred to So they rebuilt this thing. It's much
34:27
Speaker 2: more powerful, it's much quieter. Now they're sensitive to gravitational
34:31
Speaker 2: waves from a much larger part of the universe, or
34:33
Speaker 2: just quieter gravitational waves. So this is like the end
34:36
Speaker 2: of twenty fifteen. It's in September, and they're turning this
34:39
Speaker 2: thing on and you know, nobody knows what they're going
34:42
Speaker 2: to hear. And incredibly, what they heard on September fourteenth,
34:46
Speaker 2: just before eleven in the morning was a huge, perfect
34:50
Speaker 2: gravitational wave It's basically like the first few days after
34:54
Speaker 2: they turned this thing on, they heard a perfect one.
34:58
Speaker 2: It was so nice that people thought they were being fooled.
35:01
Speaker 2: And the experiment had actually done test runs where they
35:04
Speaker 2: like injected fake gravitational waves into the data to see
35:07
Speaker 2: if people notice them, you know, just to like figure
35:10
Speaker 2: out if their systems were working. They keep people honest,
35:13
Speaker 2: So everybody thought, oh, this must be one of those
35:15
Speaker 2: test ones, ha ha ha. But it wasn't. It was real.
35:18
Speaker 1: Wow, that's amazing. That's like stepping outside and suddenly seeing
35:22
Speaker 1: like a new planet just like waving at you across
35:25
Speaker 1: the sky.
35:27
Speaker 2: Or it must have been something like you know, the
35:28
Speaker 2: development of vision. There were like hundreds of millions of
35:31
Speaker 2: years before anything on Earth, any kind of life, was
35:34
Speaker 2: sensitive to photons, right, and then once we opened those
35:37
Speaker 2: first primordial eyeballs, we're like, whoa, there's a lot to
35:40
Speaker 2: see out here.
35:41
Speaker 1: That little flatworm was probably wigging out, Like what is
35:45
Speaker 1: going on? I don't even have a brain yet, and
35:48
Speaker 1: yet my mind is blown. This sounds really incredible, Daniel.
35:52
Speaker 1: If only we could hear from someone who's actually studied.
35:56
Speaker 2: This, and fortunately we can. Well, I had a fun
36:02
Speaker 2: conversation with cosmologist Angelika van Son, who told us all
36:07
Speaker 2: about why it was the surprise to hear that first
36:10
Speaker 2: gravitational wave, how many we have seen, and what we
36:13
Speaker 2: have learned about how many black holes are out there.
36:16
Speaker 1: Well, why don't we take a quick break and when
36:18
Speaker 1: we get back, I think people would like to hear
36:22
Speaker 1: from the expert.
36:36
Speaker 2: Okay, we're back, and now we're going to hear from
36:37
Speaker 2: a real expert on gravitational waves. Here's my interview with
36:42
Speaker 2: cosmologist Angelika van Son. So it's my great pleasure to
36:46
Speaker 2: introduce to the program Leka van Son, a cosmologist at
36:50
Speaker 2: Harvard working on black holes and gravitational waves, and who
36:54
Speaker 2: recently wrote a paper with the phrase monstrous black holes
36:57
Speaker 2: in the title. Nika, welcome to the program. Thank you,
37:00
Speaker 2: Thank you.
37:01
Speaker 3: Daniel, very happy to be here.
37:03
Speaker 2: So we have some basic questions about gravitational wave astronomy,
37:06
Speaker 2: especially the first days. I remember when the first discoveries
37:09
Speaker 2: were made, everybody seemed sort of surprised, like they just
37:12
Speaker 2: turned this machine on and all of a sudden they
37:14
Speaker 2: were seeing a signal. Why was it such a surprise
37:17
Speaker 2: to everybody?
37:18
Speaker 3: Okay, so there's multiple aspects here. So first of all,
37:21
Speaker 3: they did just turn a machine on, but you have
37:23
Speaker 3: to take into account that the history behind us goes
37:27
Speaker 3: back much further, Like this was already advanced Lego that
37:31
Speaker 3: they were running, and so they've been already trying to
37:34
Speaker 3: detect black holes for like twenty five years. But inherently
37:39
Speaker 3: black holes are just very rare. So about one in
37:41
Speaker 3: every ten thousand stars forms a black hole, and that's
37:46
Speaker 3: just forming one black hole. What we were seeing with
37:48
Speaker 3: Lego Virgo with gravitational waves was two black holes smashing
37:52
Speaker 3: in together, forming a newer, more massive black hole. So
37:57
Speaker 3: this brings us actually to the second part of the problem,
37:59
Speaker 3: which WHI is what's called in the literature the separation problem.
38:04
Speaker 3: So dravity is actually a very weak force, and so
38:08
Speaker 3: to merge two black holes within the age of our universe,
38:13
Speaker 3: which within a huple time, we have to put the
38:15
Speaker 3: black holes very close together on a very very short orbit. However,
38:20
Speaker 3: the massive stars that come before these black holes, that
38:23
Speaker 3: are their progenitors, they are much bigger than a small orbit.
38:27
Speaker 3: They're like a thousand times or one hundred thousand times
38:30
Speaker 3: is big. And so this is what we call the
38:33
Speaker 3: separation problem. Which basically asks the question, how can we
38:38
Speaker 3: get two stars to form two black holes and such
38:42
Speaker 3: short orbits when they cannot have worn that bain. So
38:47
Speaker 3: this is basically the whole field of trying to understand
38:50
Speaker 3: how binary black hole mergers form. And this is exactly
38:54
Speaker 3: where all the uncertainties come from. But before the first detection,
38:58
Speaker 3: we thought this was very rare. This never happens most
39:02
Speaker 3: of the time. Stars they don't form black holes right
39:06
Speaker 3: at the right location to form merging black holes.
39:09
Speaker 2: So, just to make sure I understand, you're saying that,
39:12
Speaker 2: in order to make a black hole, a star has
39:13
Speaker 2: to be sort of already anomalously big, and that also
39:17
Speaker 2: to make a pair of black holes that will merge,
39:19
Speaker 2: they have to be close together. And it's hard to
39:22
Speaker 2: understand how you get two really big stars so close together,
39:25
Speaker 2: so they form two black holes which can end up merging.
39:28
Speaker 3: Almost The thing is, indeed, these two black holes have
39:31
Speaker 3: to be really close. But the stars, throughout their life
39:35
Speaker 3: they change in their size, so throughout their life before
39:39
Speaker 3: they die and form a black hole at one point,
39:42
Speaker 3: they will be really big stars. When they get older,
39:46
Speaker 3: they swell up, just like humans tend to do when
39:49
Speaker 3: they get older, they become much bigger, and so they
39:52
Speaker 3: become so big that they wouldn't fit next to each
39:54
Speaker 3: other anymore. And what would happen, what we expect would happen,
39:58
Speaker 3: is that these stars would merge as a stellar merger.
40:01
Speaker 3: But that didn't happen because we formed two black holes.
40:05
Speaker 3: So in some way, these stars managed to lose some
40:09
Speaker 3: of their weights, to exchange some of their angular momentum,
40:13
Speaker 3: and to put the stars on different orbits than they started.
40:17
Speaker 3: So they might have started out very wide, but then
40:20
Speaker 3: exchanged mass between each other to finally end up at
40:24
Speaker 3: as very much smaller orbit but much more compact, forming
40:28
Speaker 3: two black holes.
40:29
Speaker 2: I see. So we thought this sort of arrangement, this
40:31
Speaker 2: particular dance was pretty rare and it would be hard
40:34
Speaker 2: to see black hole mergers because this configuration didn't happen
40:38
Speaker 2: very often in.
40:38
Speaker 3: The universe exactly. And this really shows how little we
40:42
Speaker 3: actually know about binary interactions, which is this exchange of
40:46
Speaker 3: mass between stars and massive stars in general, because massive
40:51
Speaker 3: stars it was not a very popular field before gravitational
40:54
Speaker 3: waves came around. If you came to your supervisor or
40:58
Speaker 3: advisor twenty years of going, you'd said, hey, I want
41:01
Speaker 3: to go and study stars. They probably say, wow, stars,
41:05
Speaker 3: that's all figured out. We know that by now, we
41:07
Speaker 3: don't have to do anything anymore. Except then they figured
41:09
Speaker 3: out in twenty twelve that most stars don't live alone.
41:13
Speaker 3: They actually live in pairs in these binaries, which can
41:17
Speaker 3: then form binary black holes. And we also found out
41:22
Speaker 3: that massive stars are wildly different from low mass stars.
41:27
Speaker 3: And we don't have any idea how these high mass
41:30
Speaker 3: stars live their life and die.
41:33
Speaker 2: What are the mysteries there? I mean, they are hotter,
41:35
Speaker 2: they burn brighter, so they shorter lived. What are the
41:38
Speaker 2: questions people are still asking?
41:40
Speaker 3: This hotter and brighter part is actually what makes it
41:43
Speaker 3: so difficult to study these stars while they're alive, because
41:47
Speaker 3: basically they live fast and die young, and as I
41:50
Speaker 3: mentioned before, they're intrinsically rare. Most stars that form will
41:55
Speaker 3: form as lower mass stars, and only a few stars
41:58
Speaker 3: will form a very small fraction of all stars will
42:02
Speaker 3: form as high mass stars. Where with high mass I
42:05
Speaker 3: now mean something of about twenty times as massive as
42:09
Speaker 3: our sun, because that's what you need to form a
42:12
Speaker 3: black hole. But because they're so intrinsically rare and so
42:16
Speaker 3: short lived, we only have a handful of stars observed
42:20
Speaker 3: while alive of the order of fifty to one hundred
42:25
Speaker 3: solar masses. So that solar mass is this unit that
42:28
Speaker 3: we use for how massive stars are. And black holes,
42:32
Speaker 3: and even when you study them, they're often shrouded in
42:37
Speaker 3: all these clouds of dust literal dusts that they've expelled themselves,
42:42
Speaker 3: making it very hard to actually observe any of the
42:45
Speaker 3: internal properties or if any of the properties of these stars.
42:49
Speaker 3: So we don't know how big they get, we don't
42:51
Speaker 3: know how much of their fuel they will use, we
42:55
Speaker 3: don't know if they're spinning, we don't know how strong
42:58
Speaker 3: their winds are. And that's just for single massive stars.
43:02
Speaker 3: Then if you make two massive stars, it's double the trouble.
43:06
Speaker 3: And so we don't know when they interact with each other,
43:10
Speaker 3: when they interact, how it proceeds, like is it a
43:14
Speaker 3: stable or an unstable interaction. So there's a lot of
43:17
Speaker 3: question marks there, and we actually hope that gravitational waves
43:21
Speaker 3: can help us shed some light on the life of
43:24
Speaker 3: these stars because black holes are basically foss sales of
43:29
Speaker 3: massive stars, and so we can use them to learn
43:33
Speaker 3: something about stars that lived long ago.
43:36
Speaker 2: All right, So then take us back to September twenty fifteen,
43:39
Speaker 2: they just turned on advanced lego. Nobody ever seen a
43:42
Speaker 2: gravitational wave with this history of like Joseph Weber and
43:45
Speaker 2: all of his claims in the field, was sort of
43:47
Speaker 2: not the most exciting one, maybe not the one people
43:50
Speaker 2: thought would yield the discovery. And then they turn this
43:53
Speaker 2: thing on and they see a signal within days or
43:56
Speaker 2: weeks of their new telescope opening this eyeball to the universe.
43:59
Speaker 2: Is does that mean about our understanding of these massive
44:02
Speaker 2: stars and how often binary black holes form? Did we
44:05
Speaker 2: totally undershoot it? Were there some people who were predicting
44:08
Speaker 2: we would see something or was it a surprise to everybody?
44:11
Speaker 3: Yeah, basically before that we indeed definitely undershot the expectation.
44:17
Speaker 3: Our population models expected much lower rate of binary black
44:21
Speaker 3: hole and black hole nutron star, etcetera. And indeed, it
44:24
Speaker 3: was right on the first date that they turned the
44:27
Speaker 3: detector on they got this beautiful signal that was so
44:30
Speaker 3: beautiful that people thought they were still looking at a
44:32
Speaker 3: test signal and someone forgotten to put the test off.
44:36
Speaker 3: But yeah, we heavily undershot with the rates. But as
44:40
Speaker 3: I mentioned, the theory of massive stellar evolution is still
44:45
Speaker 3: very uncertain. There's lots of things we need to learn
44:48
Speaker 3: about how these stars live their life, and this causes
44:51
Speaker 3: the main uncertainty in how we predict what the rates
44:55
Speaker 3: of these events will be. And so currently we're still
44:59
Speaker 3: at the stage where our models have a rates prediction
45:03
Speaker 3: that varies over multiple orders of magnitude. So the rates
45:08
Speaker 3: of Likego virgo, the rates that we see today are
45:10
Speaker 3: within that error. But we also can heavily overshoot or
45:14
Speaker 3: heavily undershoot, depending on what parameters we adopt in our models.
45:20
Speaker 3: And so piece by piece, as we are getting more
45:23
Speaker 3: information about these gravitational waves, we can constrain parts of
45:27
Speaker 3: our models, and then not just using the rate right,
45:30
Speaker 3: but also using the masses, their spins, their mass ratios,
45:34
Speaker 3: all the properties that we can get our hands on.
45:37
Speaker 3: Using that, we can slowly understand our models better and
45:42
Speaker 3: constrain them as well.
45:44
Speaker 2: I see, so we've measured now a bunch of gravitational waves.
45:46
Speaker 2: We were surprised to see them so quickly, which means
45:49
Speaker 2: we undershot them, and now we sort of adjusted all
45:51
Speaker 2: of our estimates up to match what we've observed. Can
45:55
Speaker 2: we then make any predictions, or we just fitting these
45:58
Speaker 2: rates to the data, or do we have any other
46:01
Speaker 2: alternative way to make these predictions? Now, do we have
46:03
Speaker 2: like a deeper understanding of the internal mechanisms of the
46:06
Speaker 2: massive stars, any other handle on this.
46:09
Speaker 3: Yeah, so definitely what we were trying to do is
46:12
Speaker 3: approach us from multiple sides, right, We are trying to
46:15
Speaker 3: make these predictions from our knowledge up right, So we
46:21
Speaker 3: start with what we know about stars, and then we say, okay,
46:25
Speaker 3: we expect to see this many black holes, and then
46:28
Speaker 3: some of their models actually overshoot. Some of those models
46:32
Speaker 3: undershoot in the rate that we observed. But to make
46:36
Speaker 3: a full picture of massive stars and black holes and
46:39
Speaker 3: gravitational waves, we should use all the information that we have.
46:43
Speaker 3: So we can also tailor other transient events such as supernovae,
46:49
Speaker 3: which happens when a star dies, so that's a step
46:53
Speaker 3: before you form emerging black hole or any black hole.
46:59
Speaker 3: And the supernova rate is also something that we've observed
47:02
Speaker 3: through normal electromagnetic waves. But ideally we want to match
47:07
Speaker 3: all these different rates at the same time, which will
47:10
Speaker 3: give us stronger constraints on which of our models make
47:13
Speaker 3: some sense and which of our models don't make sense interesting.
47:16
Speaker 2: And so now we have this little sample, like you know,
47:19
Speaker 2: roughly one hundred or so gravitational waves from these mergers.
47:23
Speaker 2: What are their features in there? Like we can measure
47:25
Speaker 2: the masses. Are there surprises in the masses of these
47:28
Speaker 2: black holes that we're seeing, Are there like clumps or
47:30
Speaker 2: gaps or things in there that we didn't expect?
47:33
Speaker 3: This is one hundred percent the way that we're going.
47:36
Speaker 3: The distribution of masses contains more information than just the rate,
47:41
Speaker 3: and at this moment, we've seen two features certainly in
47:46
Speaker 3: the mass distribution of merging binary black holes. We've seen
47:50
Speaker 3: one feature at higher masses which has received by far
47:55
Speaker 3: the most attention and has been really in the news
47:59
Speaker 3: a lot, and that is because this feature has been
48:03
Speaker 3: this kind of bump in a mass distribution has been
48:06
Speaker 3: linked to something that we call parents stability supernova, and
48:11
Speaker 3: that's a type of supernova that basically causes the most
48:16
Speaker 3: massive stars that would form the most massive black holes.
48:20
Speaker 3: Instead of forming a black hole, they will die prematurely,
48:24
Speaker 3: so they will go into supernova prematurely. I mean they
48:27
Speaker 3: haven't finished all their burning cycles yet, and this causes
48:32
Speaker 3: them to explode without forming any black hole at all.
48:36
Speaker 3: And so theory predicted that single stars or massive stars
48:41
Speaker 3: couldn't form black holes with masses above about forty five
48:44
Speaker 3: solar masses, and that there should be a sort of
48:47
Speaker 3: bump in the distribution right below that gap. And so
48:52
Speaker 3: the bump that we saw in the mass distribution at
48:55
Speaker 3: thirty five solar masses, people were really excited because they thought, oh,
48:59
Speaker 3: that's that bump from the parent's stability. So that means
49:03
Speaker 3: that that is the limit where normal stars can form
49:07
Speaker 3: black holes. But we don't see a gap above this bump.
49:11
Speaker 3: We still see black holes. So basically these black holes
49:15
Speaker 3: shouldn't exist, but yet they are there. And so this
49:20
Speaker 3: intrigued a lot of people in trying to figure out
49:23
Speaker 3: how can you form black holes above this kind of
49:27
Speaker 3: cutoff mass from massive stars above this parent stability limits.
49:31
Speaker 3: And so that excited a lot of people coming up
49:34
Speaker 3: with all kinds of wild ideas going from bosone stars
49:38
Speaker 3: to just galaxy clusters where you have second order or
49:43
Speaker 3: second generation black holes. But more recent work actually points
49:49
Speaker 3: towards that bump not being related to the parents stability.
49:53
Speaker 3: So I think at this point we don't know what
49:58
Speaker 3: the bump is caused by and the real bump, the
50:02
Speaker 3: real parent's stability limit should be somewhere around sixty solar
50:06
Speaker 3: masses instead of thirty solar masses where we see it now.
50:11
Speaker 3: And so I'm quite excited for the next run to
50:13
Speaker 3: see if we will discover an extra feature at sixty
50:18
Speaker 3: solar masses. I see there will exactly, and I want
50:24
Speaker 3: to understand what the bump at thirty five is doing
50:26
Speaker 3: as well. And then there's also the low mass bump.
50:30
Speaker 3: So that bump actually is also really interesting because at
50:33
Speaker 3: the moment we're not really sure if it's a bump
50:36
Speaker 3: or if it's just a continuous line. And this bump
50:41
Speaker 3: is very much related to something that we've called the
50:44
Speaker 3: neutron star black hole mask gap, which was actually thought
50:49
Speaker 3: of twenty years ago. Twenty years ago, people were looking
50:52
Speaker 3: at black holes through X ray observations, so that's you
50:56
Speaker 3: can only see black holes through X ray observations if
50:59
Speaker 3: they are create mass. And they were looking at these
51:02
Speaker 3: black holes that were treating mass, and they said, hey,
51:04
Speaker 3: all of these black holes are significantly more massive than
51:09
Speaker 3: nutron stars. So there's a gap between the most massive
51:13
Speaker 3: nutron star and the least massive black hole that we
51:15
Speaker 3: can form. And since people came up with this observation
51:20
Speaker 3: twenty years ago, it has been heavily debated over the
51:24
Speaker 3: full twenty years. But the gravitational wave detections that are
51:29
Speaker 3: now rolling in are providing us with a new opportunity
51:33
Speaker 3: to measure if this gap is real. And there's a
51:37
Speaker 3: few observations that are already contradicting this gap between neutron
51:42
Speaker 3: stars and black holes, saying that, oh, maybe there isn't
51:46
Speaker 3: a gap between nutron stars and black holes, which tells
51:50
Speaker 3: us a lot about how nutron stars and black.
51:53
Speaker 2: Holes form, So why would there be a gap.
51:55
Speaker 3: So that's a good question. This was actually a case
51:59
Speaker 3: where the theory came after the observation, so people came
52:04
Speaker 3: up with theories to explain the observation and X ray
52:08
Speaker 3: binaries saying that maybe supernova for nutron stars are just
52:14
Speaker 3: very different than supernova for black holes. Whereas, if you
52:18
Speaker 3: have a supernova for a nutron star that forms a
52:21
Speaker 3: nutron star, you manage to blow all of the outer
52:24
Speaker 3: layers away and you only keep the core nutron star
52:28
Speaker 3: that's in the inner bit of your star, Whereas if
52:30
Speaker 3: you become slightly more massive and you have a core
52:34
Speaker 3: that will form a black hole. Then the explosion is
52:38
Speaker 3: no longer strong enough to really throw away all the
52:41
Speaker 3: outer layers of the star, and part of these outer
52:45
Speaker 3: layers fall back onto the proto black protein compact objects.
52:51
Speaker 3: And so these extra layers add on an extra fuel
52:54
Speaker 3: solar masses, bumping the mass up to by a few
52:59
Speaker 3: solar mass, thereby creating a gap in a random mass distribution.
53:04
Speaker 2: Wow. Fascinating. So what are you looking forward to seeing
53:08
Speaker 2: in this next run of Advanced Lego and Virgo and Carga,
53:12
Speaker 2: the one that's just starting.
53:13
Speaker 3: Yeah, So the most exciting observations are always the crazy outliers,
53:18
Speaker 3: because things that are outliers are things that we don't expect.
53:23
Speaker 3: So they mean that we have to readjust our theory
53:25
Speaker 3: or figure out something new, which as a theorist I
53:28
Speaker 3: love to do. I mean, something super fun would be
53:32
Speaker 3: something that contradicts both mask gaps. So something that is
53:35
Speaker 3: in the lower end this upper mask gap at the
53:37
Speaker 3: same time, that's something wild. I don't expect that to happen,
53:42
Speaker 3: which is exactly why you're so exciting, but.
53:45
Speaker 2: It sounds like you're secretly hoping for it, exactly.
53:48
Speaker 3: I always like when things have to be thrown over
53:51
Speaker 3: and we can start at the drawing table.
53:53
Speaker 2: Again. Those are the most fun moments in history, absolutely exactly.
53:57
Speaker 3: So what I'm more realistically excited about is, as I
54:04
Speaker 3: just mentioned, at the low masses, I would like to
54:07
Speaker 3: know if that's really truly empty or not. Is there
54:10
Speaker 3: a gap between neutron stars and black holes or not,
54:13
Speaker 3: And is there another feature at about sixty solar masses
54:18
Speaker 3: or not. These are things that we can probably hopefully
54:21
Speaker 3: see in the next four run. But also I've been
54:26
Speaker 3: talking a lot about the masses, but I'd be very
54:29
Speaker 3: excited if we got a certain observation of a system
54:35
Speaker 3: with a lot of eccentricity or with a lot of spin,
54:38
Speaker 3: because those barometers are more difficult to measure, so we
54:43
Speaker 3: kind of need a golden event in order to be
54:46
Speaker 3: able to make a proper observation there. So I would
54:49
Speaker 3: love if we have one or two golden events in
54:51
Speaker 3: the next run so that we can say something about
54:54
Speaker 3: these spins and eccentricities.
54:56
Speaker 2: What makes an event golden is the orientation of the
54:58
Speaker 2: system relative to Earth or something.
55:00
Speaker 3: Yeah, and it's location basically, So it's golden if it
55:04
Speaker 3: has a very high signals to noise ratio, and you
55:07
Speaker 3: can do that by being very loud and very nearby.
55:10
Speaker 3: So loud events are more massive events, and so you
55:15
Speaker 3: can also do things if they're more easily distinguished, things
55:19
Speaker 3: if they're quite of extreme. Right, So if you have
55:22
Speaker 3: a very extreme mass ratio and it's quite nearby, it's
55:26
Speaker 3: easier to constrain what that is.
55:28
Speaker 2: Extreme mass ratio means like a big black hole and
55:31
Speaker 2: a small black hole merging.
55:32
Speaker 3: Yes, so it's a very big black hole at a
55:34
Speaker 3: very small black hole.
55:35
Speaker 2: Cool. And what do you think are the prospects for
55:38
Speaker 2: these future facilities like the Einstein Telescope or Lisa, do
55:42
Speaker 2: you think we'll see those things in our lifetime or
55:44
Speaker 2: in your career?
55:45
Speaker 3: Yeah? I really really hope. So, because I'm extremely excited
55:49
Speaker 3: about third generator. We call all these new facilities, we
55:52
Speaker 3: call them third generation detectors. We're currently we're kind of
55:56
Speaker 3: at second generation, and they're going to be wildly exciting because,
56:00
Speaker 3: first of all, they're going to give us thousands of
56:03
Speaker 3: golden events, so we're going to be able to measure
56:06
Speaker 3: everything to extreme precision. Secondly, because these facilities like Cosmic
56:12
Speaker 3: Explorer and the Einstein telescope. They'll be much bigger, like
56:16
Speaker 3: ten times bigger than the experiments that we have today.
56:19
Speaker 3: They will allow us to see the very early universe,
56:23
Speaker 3: or how we would call it, the very high redshift. Especially,
56:27
Speaker 3: they would see black hole mergers at redshift one hundred.
56:31
Speaker 3: And to bubble your mind about what rechift one hundred means,
56:36
Speaker 3: if the universe were condensed into one year, then the
56:40
Speaker 3: Earth was born in August and humanity came around in
56:44
Speaker 3: the last I don't know, twenty minutes or so, then
56:46
Speaker 3: redshift one hundred would be ten am on January first,
56:51
Speaker 3: so that we'll be right at the beginning of the universe,
56:55
Speaker 3: and the first stars we expect to be born at
56:59
Speaker 3: January third, so later than where we could throwe the
57:03
Speaker 3: first merging black holes. Now, if you followed along a
57:08
Speaker 3: little bit, you might be thinking, wait, how are you
57:11
Speaker 3: forming a black hole without a star, And that'd be
57:14
Speaker 3: a good question. We don't know, but there is a
57:17
Speaker 3: theory that you can form black holes without stars, and
57:20
Speaker 3: we call them primordial black holes. And these are black
57:24
Speaker 3: holes that form out of the fluctuations of the birth
57:29
Speaker 3: of our universe. So it's very science fiction, kind of
57:32
Speaker 3: spacey but we would be able to detect these with
57:35
Speaker 3: next generation detectors, So there's just an endless possibility of
57:41
Speaker 3: things that we're going to see. Also, there's, of course,
57:45
Speaker 3: you have to keep in mind that we're seeing a
57:46
Speaker 3: whole new force of nature. Gravity is not electromagnetic lights,
57:51
Speaker 3: which we normally see. So there's just going to be
57:53
Speaker 3: a whole lot of unknown unknowns of things that we
57:56
Speaker 3: can't even predict that what they are, but we're probably
57:59
Speaker 3: going to see them. And then the third thing is
58:02
Speaker 3: that now all I've been talking about is earth based
58:06
Speaker 3: or ground based detectors, so detectors or gravitational waves that
58:10
Speaker 3: we put on the Earth. But if you really want
58:13
Speaker 3: to detect very different systems, you have to go to
58:18
Speaker 3: very different wavelengths, and you have.
58:19
Speaker 2: To go to space.
58:20
Speaker 3: Because gravitational waves work similar to sound. So if you
58:26
Speaker 3: want to see a more massive thing, you have to
58:30
Speaker 3: look at lower frequencies, just as if a very big
58:35
Speaker 3: bell will ring at lower frequencies than a very small bell.
58:39
Speaker 3: So big black holes low frequencies, just like big bells
58:42
Speaker 3: low frequencies, and the big frequencies that we want to
58:45
Speaker 3: go to are of the order of the size of
58:48
Speaker 3: the Earth. So LISA is this next generation space based
58:53
Speaker 3: experiment where we basically have three satellites following the Earth,
58:58
Speaker 3: shooting lasers at each other and working as a gravitational
59:01
Speaker 3: wave detector like that, and they will be able to
59:04
Speaker 3: see super massive black holes. So now we're seeing black
59:08
Speaker 3: holes with thirty times the mass of the Sun. Then
59:10
Speaker 3: we will see black holes but a million times the
59:13
Speaker 3: mass of the Sun.
59:14
Speaker 2: So the biggest black holes make the longest wavelengths gravitational waves,
59:18
Speaker 2: and to see them, we need a bigger detector to
59:20
Speaker 2: capture those long wavelengths.
59:22
Speaker 3: Exactly.
59:23
Speaker 2: Awesome. Well, that sounds like a lot of fun. Do
59:25
Speaker 2: you feel like in thirty years when graduate students have like,
59:29
Speaker 2: you know, thousands and thousands of golden events on their laptops,
59:32
Speaker 2: you're going to be like, in my day, we were
59:34
Speaker 2: lucky to get just one. I wrote my whole thesis
59:37
Speaker 2: on two.
59:37
Speaker 3: You remember when the first detection black holes was out there? Yeah,
59:42
Speaker 3: and they're going to be okay, hooomer or whatever.
59:47
Speaker 2: Yeah. Well I feel that way because I share with
59:50
Speaker 2: undergraduates these data samples from the Large Hadron Collider that
59:53
Speaker 2: have like tens of thousands of top quarks in them,
59:55
Speaker 2: and I literally wrote my PhD on four top quark events,
59:59
Speaker 2: so that's literally my experience. But it's wonderful. It's progress, right,
1:00:02
Speaker 2: I'm glad that everybody gets to marinate in all this
1:00:05
Speaker 2: data and hope we all find surprises in it.
1:00:08
Speaker 3: Yeah, it will be a very exciting time. I'm looking
1:00:10
Speaker 3: forward to the next thirty years so wonderful.
1:00:13
Speaker 2: Well, thanks very much for telling us about this exciting field,
1:00:16
Speaker 2: all the surprises in the past and some of the
1:00:18
Speaker 2: surprises that we can look forward to in the future.
1:00:20
Speaker 2: Really appreciate your time.
1:00:21
Speaker 3: Yeah, thank you very much for having me.
1:00:23
Speaker 1: I mean, you could have, instead of that amazing interview
1:00:27
Speaker 1: just ask me to guess a bunch of stuff. But
1:00:29
Speaker 1: you know that's fine. It's fine too to actually listen
1:00:33
Speaker 1: to someone who has studied this.
1:00:34
Speaker 2: I love how you can hear in her voice the
1:00:37
Speaker 2: joy at these discoveries, you know, hearing these discoveries from
1:00:40
Speaker 2: the universe, and also the excitement for the future. There's
1:00:44
Speaker 2: so many things we still have to learn about gravitational waves,
1:00:47
Speaker 2: the kind of things that we might learn from future
1:00:49
Speaker 2: gravitational wave experiments, These crazy plans they have to build
1:00:53
Speaker 2: future detectors that are much bigger or that are floating
1:00:57
Speaker 2: in space. It's exciting to think about all the things
1:01:00
Speaker 2: that we might learn.
1:01:01
Speaker 1: I mean, it really does sound like we have now
1:01:03
Speaker 1: discovered a new secret language of the universe.
1:01:07
Speaker 2: We are definitely building out our capacity to listen to
1:01:10
Speaker 2: the secrets of the universe, to eavesdrop on the universe
1:01:13
Speaker 2: and violate its price.
1:01:15
Speaker 1: That's a creepy way to put it, but I like it.
1:01:17
Speaker 2: Maybe we need to get the universe's consent, or at
1:01:20
Speaker 2: least the universe's parents consent before we do more experiments, before.
1:01:23
Speaker 1: We swab the universe's cheeks. We got to get consent.
1:01:27
Speaker 2: So there we go, folks. The answer is that we
1:01:29
Speaker 2: have discovered a lot more gravitational waves than anybody dared hope.
1:01:33
Speaker 2: As soon as we turned on this new kind of
1:01:35
Speaker 2: ear to the universe, we heard all sorts of stuff
1:01:37
Speaker 2: going on out there, and it hasn't quieted down ever since.
1:01:41
Speaker 2: So fortunately, the universe is a very noisy place when
1:01:44
Speaker 2: it comes to gravity.
1:01:45
Speaker 1: Like whoa dude, cow bunga serfs up on those gravitational waves.
1:01:51
Speaker 2: Bra All right, thanks very much Katie for going on
1:01:54
Speaker 2: this tour with us of the history of gravitational Wave Astronomy.
1:01:58
Speaker 1: Thanks for having me Brok.
1:02:00
Speaker 2: Thank everybody for listening. Tune in next time. Thanks for listening,
1:02:10
Speaker 2: and remember that Daniel and Jorge Explain the Universe is
1:02:13
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1:02:22
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