See all Lex Fridman transcripts on Youtube

Speaker 1

01:00:00

Low frequency. So, what you feel isn't, you feel it go smoothly, okay? All right. So,

Speaker 2

01:00:11

we also work at this frequency. So, we Basically, why do we have to do anything other than shock absorbers? So we made the world's fanciest shock absorbers, okay?

Speaker 2

01:00:25

Not just like in your car where there's 1 layer of them. They're just the right squishiness and so forth. They're better than what's in the cars. And we have 4 layers of it, so whatever shakes and gets through the first layer, we treat it in a second, third, fourth layer.

Speaker 3

01:00:39

So it's a mechanical engineering problem.

Speaker 2

01:00:41

Yeah, that's what I said. So it's a

Speaker 3

01:00:42

real thing. There's no weird tricks to it, like a chemistry type thing?

Speaker 2

01:00:47

No, no, just, well, the right squishiness, so you need the right material inside. And ours look like little springs, but they're.

Speaker 3

01:00:55

Springs, they're springs? So like legitimately like shock absorbers.

Speaker 2

01:01:00

Yeah.

Speaker 3

01:01:01

What?

Speaker 2

01:01:03

Okay. Okay, and this is now experimental physics at its limit. Okay, so you do this, and we make the world's fanciest shock absorbers, just mechanical engineering.

Speaker 3

01:01:13

Just mechanical engineering, this is hilarious.

Speaker 2

01:01:15

But we didn't test, we weren't good enough to discover gravitational waves. So, we did another, we added another feature, and it's something else that you're aware of, probably have 1. And that is to get rid of noise.

Speaker 2

01:01:34

You've probably noise, which is you don't like, and that's the same principle that's in these little Bose earphones.

Speaker 3

01:01:43

Noise canceling.

Speaker 2

01:01:44

Noise canceling. So how do they work? They basically, you go on an airplane and they sense the ambient noise from the engines and cancel it, because it's just the same over and over again, they cancel it.

Speaker 2

01:01:58

And when the stewardess comes and asks you whether you want coffee or tea or a drink or something, you hear her fine because she's not ambient, she's a signal.

Speaker 3

01:02:07

Are we talking about active canceling? Like where the

Speaker 2

01:02:09

action's different? Active canceling.

Speaker 3

01:02:12

This is, okay. So another. So tell me you have active canceling on this.

Speaker 3

01:02:17

Yeah, yeah. Besides the shock absorbers.

Speaker 2

01:02:20

So inside this array of shock absorbers, you asked for some interesting. This is awesome. So inside this, it's harder than the earphone problem, but it's just engineering.

Speaker 2

01:02:33

We have to see, measure not just that the engine still made noise, but the earth is shaking, it's moving in some direction. So we have to actually tell not only that there's noise and cancel it, but what direction it's from. So we put this array of seismometers inside this array of shock absorbers and measure the residual motion and its direction. And we put little actuators that push back against it and cancel it.

Speaker 2

01:03:08

That's awesome.

Speaker 3

01:03:10

So you have the actuators and you have the thing that is sensing the vibrations and then you have the actuators that adjust to that and do so in perfect synchrony.

Speaker 2

01:03:18

Yeah. What? If it all works right. And so how much do we reduce the shaking of the earth?

Speaker 3

01:03:25

I mean.

Speaker 2

01:03:26

1 part in 10 to the 12th.

Speaker 3

01:03:29

1 part in 10 to

Speaker 2

01:03:31

the 12th. So what gets through us is 1 part in 10 to the 12th. That's a pretty big reduction.

Speaker 2

01:03:38

You don't need that in your car, but that's what we do. And so that's how isolated we are from the Earth. And that was the biggest, I'd say, technical problem outside of the physics instrument, the interferometer. Can I

Speaker 3

01:03:50

ask you a weird question here? You make it very poetically and humorously. You're saying it's just a mechanical engineering problem.

Speaker 3

01:03:58

But is this 1 of the biggest precision mechanical engineering efforts ever? I mean, this seems exceptionally difficult.

Speaker 2

01:04:09

It is, and so it took a long time. And I think nobody seems to challenge the statement that this is the most precise instrument that's ever been built, LIGO.

Speaker 3

01:04:22

I wonder what listening to Led Zeppelin sounds on this thing, because it's so isolated. I mean, this is like, I don't know. No background noise.

Speaker 3

01:04:31

No background, it's wow, wow, wow. So when you were first conceiving this, I would probably, if I was knowledgeable enough, kind of laugh off the possibility that this is even possible. I'm sure, like how many people believe that this is possible? Did you believe

Speaker 2

01:04:53

this was possible? I did. I didn't know that we needed, for sure that we needed active when we started.

Speaker 2

01:05:00

We did just passive, but we were doing the tests to develop the active to add as a second stage which we ended up needing. But there was a lot of, you know, now there was a lot of skepticism. A lot of us, especially astronomers, felt that money was being wasted, as we were all so expensive. Doing what I told you is not cheap.

Speaker 2

01:05:24

So it was kind of controversial. It was funded by the National Science Foundation.

Speaker 3

01:05:31

Can you just linger on this just for a little longer, the actuator thing, the act of canceling? Do you remember little experiments that were done along the way to prove to the team, to themselves, that this is even possible? Because I work with quite a bit of robots, and to me the idea that you could do it this precisely is humbling and embarrassing, frankly.

Speaker 3

01:05:59

Because like, This is another level of precision that I can't even, because robots are a mess. And this is basically 1 of the most precise robots ever. Right, so is there, do you have any like small scale experiments that were done that just be like, this is possible?

Speaker 2

01:06:21

Yeah, and larger scale. We made a test that also has to be in vacuum too, but we made test chambers that had this system in it, our first mock of this system, so we could test it and optimize it and make it work. But it's just a mechanical engineering problem.

Speaker 3

01:06:42

Okay. I think. And humans are just ape descendants. I gotcha.

Speaker 3

01:06:46

I gotcha. Is there any video of this, like some kind of educational purpose visualizations of this active canceling?

Speaker 2

01:06:59

I don't think

Speaker 3

01:06:59

so. I mean, does this live on?

Speaker 2

01:07:05

Well, we work for parts of it, for the active canceling, we worked with, for the instruments, for the sensor and instruments, we worked with a small company near where you are, because it was our MIT people that got them, they were interested in the problem because they thought they might be able to commercialize it for making stable tables to make microelectronics, for example, which are limited by how stable the table is. I mean, at this point, it's a little expensive.

Speaker 3

01:07:36

So. You never know, you never know where this leads. So maybe on the, let me ask you just, sticking at it a little longer, this silly old mechanical engineering problem. What was to you kind of the darkest moment of what was the hardest stumbling block to get over on the engineering side?

Speaker 3

01:08:01

Like, was there any time where there was a doubt where it's like, I'm not sure we would be able to do this, a kind of a engineering challenge that was hit. Do you remember anything like that?

Speaker 2

01:08:10

I think the 1 that my colleague at MIT, Ray Weiss worked on so hard and was much more of a worry than this. This is only a question if you'd not do it well enough, you'd have to keep making it better somehow. But this whole Huge instrument has to be in vacuum.

Speaker 2

01:08:33

And the vacuum tanks are this big around. And so it's the world's biggest high vacuum system. And so how do you make it, first of all? How do you make this 4 meter long sealed vacuum system?

Speaker 2

01:08:50

It has to be

Speaker 3

01:08:50

made out of- 4 kilometers long.

Speaker 2

01:08:51

4 kilometers long, would I say something else? Meters. 4 kilometers long.

Speaker 3

01:08:56

Big difference.

Speaker 2

01:08:56

Yeah, but to make it, We started with a roll of stainless steel and then we roll it out like a spiral so that there's a spiral weld on it. Okay, so the engineering was fine, we did that. We worked through very good companies and so forth to build it.

Speaker 2

01:09:20

But the big worry was what if you develop a leak? This is a high vacuum, not just vacuum system. Typically in a laboratory, if there's a leak, you put helium around the thing you have and then you detect where the helium is coming in. But if you have something as big as this, you can't surround it with helium.

Speaker 3

01:09:44

So you might not actually even know that there's a leak and it will be affecting it.

Speaker 2

01:09:48

Well, we can measure how good the vacuum is so we can know that, but a leak can develop and then we don't, how do we fix it or how do we find it? And so that was, you asked about a worry, that was always a really big worry.

Speaker 3

01:10:06

What's the difference between a high vacuum and a vacuum? What is high vacuum? That's like some delta close to vacuum?

Speaker 3

01:10:15

Is it some threshold?

Speaker 2

01:10:16

Well, there's a unit, High vacuum is when the vacuum in the units that are used, which are TORs, there's 10 to the minus 9. Gotcha. And there's high vacuum is usually used in small places.

Speaker 2

01:10:31

The biggest vacuum system period is at CERN in this big particle accelerator, but the high vacuum where they need really good vacuum so particles don't scatter in it is smaller than ours. So ours is a really large high vacuum system.

Speaker 3

01:10:48

I don't know, this is so cool. I mean, this is basically by far the greatest listening device ever built by humans. The fact that like descendants of apes could do this, that evolution started with single cell organisms.

Speaker 3

01:11:04

I mean, is there any more, I'm a huge, theory is like, yeah, yeah. But like bridges, when I look at bridges from a civil engineering perspective, it's 1 of the most beautiful creations by human beings. It's physics, You're using physics to construct objects that can support huge amount of mass. And it's like structural, but it's also beautiful in that humans can collaborate to create that throughout history.

Speaker 3

01:11:27

And then you take this on another level. This is like, this is like exciting to me beyond measure that humans can create something so precise.

Speaker 2

01:11:40

But another concept lost in this, you just said, you started talking about single cell. Yeah. Okay, You have to realize this discovery that we made that everybody's bought off on happened 1.3 billion years ago somewhere.

Speaker 3

01:11:55

And

Speaker 2

01:11:55

then the signal came to us. 1.3 billion years ago, we were just converting on the Earth from single cell to multi-cell life. So when this actually happened, this collision of 2 black holes, we weren't here.

Speaker 2

01:12:09

We weren't even close

Speaker 3

01:12:10

to being here. And we're both developing

Speaker 2

01:12:11

slowly. Yeah, we were going from single cell to multi-cell life at that point.

Speaker 3

01:12:16

All to meet up at this point. Yeah. Wow, that's like, that's almost romantic.

Speaker 3

01:12:25

It is. Okay, so on the human side of things, it's kind of fascinating because you're talking about over a thousand people team for LIGO. They started out with around a hundred and you've for parts of the time at least led this team. What does it take to lead a team like this of incredibly brilliant theoreticians and engineers and just a lot of different parties involved, a lot of egos, a lot of ideas.

Speaker 3

01:13:02

You had this funny example, I forget where, where in publishing a paper you have to all agree on like, you know, the phrasing of a certain sentence or the title of the paper and so on. That's a very interesting, simple example. I'd love you to speak to that, but just in general, what does it take to lead this kind of team?

Speaker 2

01:13:23

Okay, I think the general idea is 1 we all know. You want to get where the sum of something is more than the individual parts, is what we say,

Speaker 3

01:13:39

right? Yeah.

Speaker 2

01:13:40

So, that's what you're trying to achieve.

Speaker 3

01:13:42

Yes. Okay.

Speaker 2

01:13:42

How do you do that actually? Mostly, if we take multiple objects or people, I mean, you put them together, the sum is less. Yes.

Speaker 2

01:13:52

Why? Because they overlap. So you don't have individual things that, you know, this person does that, this person does that, then you get exactly the sum. But what you want is to develop where you get more than what the individual contributions are.

Speaker 2

01:14:09

We know that's very common. People use that expression everywhere. It's the expression that has to be built into how people feel it's working. Because if you're part of a team and you realize that somehow the team is able to do more than the individuals could do themselves then they buy on in terms of the process.

Speaker 2

01:14:34

That's the goal that you have to have is to achieve that. That means that you have to realize parts of what you're trying to do that require, not that 1 person couldn't do it, it requires the combined talents to be able to do something, that neither of them could do themselves. We have a lot of that kind of thing. I think I'm going to build into some of the examples that I gave you.

Speaker 2

01:15:09

The key almost in anything you do is the people themselves. In our case, the first and most important was to attract, to spend years of their life on this, the best possible people in the world to do it. So the only way to convince them is that somehow it's better and more interesting for them than what they could do themselves. And so that's part of this idea.

Speaker 3

01:15:40

I got you, yeah, that's powerful. But nevertheless, there's best people in the world, there's egos. Is there something to be said about managing egos?

Speaker 2

01:15:48

Or that's the human problem is always the hardest. And so there's, that's an art, not a science, I think. I think the fact here that combined, there's a romantic goal that we had to do something that people hadn't done before, which was important scientifically and a huge challenge, enabled us to say, take and get, I mean, what we did just to take an example, we used the light to go in this thing comes from lasers.

Speaker 2

01:16:26

We need a certain kind of laser. So, the kind of laser that we used, there were 3 different institutions in the world that had the experts that do this, maybe in competition with each other. So, we got all 3 to join together and work with us to work on this as an example. They had the thing that they were working together on a kind of object that they wouldn't have otherwise, and were part of a bigger team where they could discover something that isn't even engineers.

Speaker 2

01:17:01

These are engineers that do laser, so, and they're part of our laser physicists.

Speaker 3

01:17:07

So could you describe the moment or the period of time when finally this incredible creation of human beings led to a detection of gravitational waves?

Speaker 2

01:17:21

It's a long story. Unfortunately, this is a part that

Speaker 3

01:17:25

we started. Failures along the way kind of thing?

Speaker 2

01:17:28

All failures, that's all, it's built into it. If you're not a,

Speaker 3

01:17:32

if you're not. Mechanical engineering.

Speaker 2

01:17:35

You build on your failures, that's expected. So we're trying things that no one's done before. So it's technically not just gravitational waves.

Speaker 2

01:17:43

And so it's built on failures. But anyway, we did before me, even the people did R&D on the concepts. But starting in 1994, we got money from the National Science Foundation to build this thing. It took about 5 years to build it.

Speaker 2

01:18:04

So by 1999, we had built the basic unit. It did not have active seismic isolation at that stage. Didn't have some other things that we have now. What we did at the beginning was stick to technologies that we had at least enough knowledge that we could make work or had tested in our own laboratories.

Speaker 2

01:18:34

And so then we put together the instrument, we made it work. It didn't work very well, but it worked. And we didn't see any gravitational waves. Then we figured out what limited us and we went through this every year for almost 10 years, never seeing gravitational waves.

Speaker 2

01:18:54

We would run it, looking for gravitational waves for months, learn what limited us, fix it for months, then run it again. Eventually, we knew we had to take another big step, and that's when we made several changes, including adding these active seismic isolation, which turned out to be a key. And we fortunately got the National Science Foundation to give us another couple hundred million dollars, a hundred million more, and We rebuilt it, or fixed, or improved it. And then in 2015, we turned it on.

Speaker 2

01:19:43

And We almost instantly saw this first collision of 2 black holes. And then we went through a process of do we believe what we've seen?

Speaker 3

01:20:00

Yeah, I think you're 1 of the people that went through that process. Sounds like some people immediately believed it. Yeah.

Speaker 3

01:20:06

And then you were like, so it's disgusting.

Speaker 2

01:20:07

So as human beings, we all have different reactions to almost anything. And so quite a few of my colleagues had a eureka moment immediately. I mean, it's the- It's amazing.

Speaker 2

01:20:19

The figure that we put in our paper, first is just data. We didn't have to go through fancy computer programs to do anything. And we show next to it the calculations of Einstein's equations. It looks just like what we detected.

Speaker 2

01:20:39

Wow. And we did it in 2 different detectors halfway across the US. So it was pretty convincing, But you don't want to fool yourself. So we had a, being a scientist, we had a, for me, we had to go through and try to understand that the instrument itself, which was new, I said we had rebuilt it, couldn't somehow generate things that look like this.

Speaker 2

01:21:04

That took some tests. And then the second, you'll appreciate more, we had to somehow convince ourselves we weren't hacked in some clever way.

Speaker 3

01:21:14

Cyber security question.

Speaker 2

01:21:15

Yeah, even though we're not on the internet. Yeah,

Speaker 3

01:21:20

no, it can be physical access too. Yeah, that's fascinating. It's fascinating that you would think about that.

Speaker 3

01:21:26

I mean, not enough. I mean, because it matches prediction. So the chances of it actually being manipulated is very, very low. But nevertheless.

Speaker 2

01:21:40

We still could have disgruntled old graduate students who had worked with us earlier.

Speaker 3

01:21:46

I don't know how that's supposed to embarrass you. I suppose, yeah, I suppose I see. But about what I think you said, within a month you kind of convinced yourself.

Speaker 3

01:21:56

Within a

Speaker 2

01:21:57

month we convinced ourselves. We kept 1,000 collaborators quiet during that time. Then we spent another month or so trying to understand what we'd seen so that we could do the science with it instead of just putting it out to the world and let somebody else understand that it was 2 black holes and what it was.

Speaker 3

01:22:18

The fact that a thousand collaborators were quiet is a really strong indication that this is a really close-knit team.

Speaker 2

01:22:25

Yeah, and they're around the world. Or either strong-knit or tight-knit or had a strong dictatorship or something.

Speaker 3

01:22:36

Yeah, either fear or love. You can rule by fear or love.

Speaker 2

01:22:39

Yeah, right. Or you

Speaker 3

01:22:39

can go back to Machiavelli. All right, well, this, I mean, this is really exciting that that was, that's a success story, because it didn't have to be a success story. I mean, eventually, perhaps you could say it'll be an event but it could have taken it over a century to get there.

Speaker 2

01:23:00

Oh yeah, yeah. And it's only downhill now.

Speaker 3

01:23:09

What do you mean it's only, you mean with gravitational waves?

Speaker 2

01:23:12

Well, yeah, we've now, we now, well now we're off because of the pandemic, but when we turned off, we were seeing some sort of gravitational wave event each week. Now we're fixing, we're adding features where it'll probably be, when we turn back on next year, it'll probably be 1 every couple of days. They're not all the same.

Speaker 2

01:23:37

It's learning about what's out there in gravity instead of just optics. It's all great. We're only limited by the fantastic thing other than that this is a great field and it's all new and so forth is that experimentally, the great thing is that we're limited by technology and technical limitations, not by science. So, another really important discovery that was made before ours was what's called the Higgs boson, made on the big accelerator at CERN.

Speaker 2

01:24:21

You know, this huge accelerator, they discovered a really important thing. It's, you know, we have Einstein's equation, E equals MC squared. So energy makes mass or mass can make energy and that's the bomb. But the mechanism by which that happens, not vision but how do you create mass from energy was never understood until there was a theory of it about 70 years ago now.

Speaker 2

01:24:54

And so, they discovered it's named after a man named Higgs. It's called the Higgs boson. And so, it was discovered. But since that time, and I worked on those experiments, since that time, they haven't been able to progress very much further.

Speaker 2

01:25:09

A little bit, but not a lot further. And the difference is that we're really lucky in what we're doing, in that there, you see this Higgs boson, but there's tremendous amount of other physics that goes on, and you have to pick out the needle in the haystack of physics. You can't make the physics go away, it's there. In our case, we have a very weak signal, but once we get good enough to see it, it's weak compared to where we've reduced the background.

Speaker 2

01:25:39

But the background is not physics, it's just technology. It's getting ourselves better isolated from the Earth or getting a more powerful laser. And so, each time, since 2015, when we saw the first 1, we continually can make improvements that are enabling us to turn this into a real science to do astronomy, a new kind of astronomy. It's a little like astronomy.

Speaker 2

01:26:07

I mean, Galileo started the field. I mean, he basically took lenses that were made for classes And he didn't invent the first telescope, but made a telescope, looked at Neptune, and saw that it had 4 moons. That was the birth of not just using your eyes to understand what's out there. And since that time, we've made better and better telescopes, obviously, and astronomy thrives.

Speaker 2

01:26:39

And in a similar way, we're starting to be able to crawl, But we're starting to be able to do that with gravitational waves. And it's going to be more and more that we can do as we can make better and better instruments. Because as I say, it's not limited by picking it out of others. Yeah, it's not limited by the physics.

Speaker 3

01:27:02

It's something about engineering. So you have an optimism about engineering, that as human progress marches on, engineering will always find a way to build a large enough device, accurate enough device to detect the signal.

Speaker 2

01:27:19

As long as it's not limited by physics, yeah, they'll do it.

Speaker 3

01:27:25

So you, 2 other folks, and the entire team won the Nobel Prize for this big effort. There's a million questions I can ask for, but looking back, Where does the Nobel Prize fit into all of this? You know, if you think hundreds of years from now, I venture to say that people will not remember the winners of a prize, but they'll remember creations like these.

Speaker 3

01:28:03

Maybe I'm romanticizing engineering. But I guess I wanna ask how important is the Nobel Prize in all of this?

Speaker 2

01:28:13

Well, that's a complicated question. As a physicist, it's something, if you're trying to win a Nobel Prize, forget it, because they give 1 a year. So, there's been 200 physicists who have won the Nobel Prize since 1900.

Speaker 2

01:28:37

And so, things just have to fall right. So, your goal cannot be to win a Nobel Prize. It wasn't my dream. It's tremendous for science.

Speaker 2

01:28:49

I mean, why the Nobel Prize for a guy that made dynamite and stuff is what it is.

Speaker 3

01:28:55

It's

Speaker 2

01:28:55

a long story. But it's the 1 day a year where actually the science that people have done is all over the world and so forth. Forget about the people again, you know, it is really good for science.

Speaker 3

01:29:08

Celebrating science.

Speaker 2

01:29:10

It celebrates science for, you know, several days, different fields, you know, chemistry, medicine and so forth. And everybody doesn't understand everything about these. They're generally fairly abstract, but then it's, you know, it's on the front page of newspapers around the world.

Speaker 2

01:29:28

So it's really good for science. It's not easy to get science on the front page of the New York Times, it's not there. Should be, but it's not. And so the Nobel Prize is important in that way.

Speaker 2

01:29:43

It's otherwise, you know, I have a certain celebrity that I didn't have before.

Speaker 3

01:29:52

And now you get to be a celebrity that advertises science. It's a mechanism to remind us how incredible, how much credit science deserves and everything.

Speaker 2

01:30:03

Well, it has a little bit more. 1 thing I didn't expect, which is good, is that we have a government, I'm not picking on ours necessarily, but it's true of all governments, are not run by scientists. In our case, it's run by lawyers and businessmen.

Speaker 2

01:30:23

Okay? And at best, they may have an aide or something that knows a little science. So our country is, and all countries, are hardly to take into account science in making decisions.

Speaker 3

01:30:42

Yes.

Speaker 2

01:30:43

Okay. And Having a Nobel Prize, the people in those positions actually listen. So, you have more influence. I don't care whether it's about global warming or what the issue is.

Speaker 2

01:30:59

There's some influence which is lacking otherwise. And people pay attention to what I say. If I talk about global warming, they wouldn't have before I had the Nobel Prize.

Speaker 3

01:31:12

Yeah, this is very true. You're like the celebrities who talk. Celebrity has power.

Speaker 2

01:31:19

Celebrity has power.

Speaker 3

01:31:20

And that's a good thing. That's a good thing, yeah.

Speaker 2

01:31:23

Singling out people, I mean, on the other side of it, singling out people has all kinds of, whether it's for Academy Awards or for this, have unfairness and arbitrariness and so forth and so on. So, you know, that's the other side of the coin. Just

Speaker 3

01:31:41

like you said, especially with the huge experimental projects like this, you know, It's a large team and it does the nature of the Nobel prizes, singles out a few individuals to represent the team. Nevertheless, it's a beautiful thing. What are ways to improve LIGO in the future, increase the sensitivity?

Speaker 3

01:32:01

I've seen a few ideas that are kind of fascinating. Are you interested in them? I'm not speaking about 5 years, perhaps you could speak to the next 5 years, but also the next hundred years.

Speaker 2

01:32:13

Yeah, so Let me talk to both the instrument and the science. Sure. So, they go hand in hand.

Speaker 2

01:32:20

I mean, the thing that I said is if we make it better, we see more kinds of weaker objects and we do astronomy, okay? We're very motivated to make a new instrument, which will be a big step, the next step, like making a new kind of telescope or something. And the ideas of what that instrument should be haven't converged yet. There's different ideas in Europe.

Speaker 2

01:32:47

They've done more work to develop the ideas, but they're different from ours and we have ideas. But I think over the next few years, we'll develop those. The idea is to make an instrument that's at least 10 times better than what we have, what we can do with this instrument, 10 times better than that. 10 times better means you can look 10 times further out.

Speaker 2

01:33:14

10 times further out is a thousand times more volume. So you're seeing much, much more of the universe. The big change is that if you can see far out, you see further back in history.

Speaker 3

01:33:28

Yeah, you're traveling back in time.

Speaker 2

01:33:30

Yeah, and so we can start to do what we call cosmology instead of astronomy or astrophysics. Cosmology is really the study of the evolution of the-

Speaker 3

01:33:43

Oh, interesting, yeah.

Speaker 2

01:33:45

And so then you can start to hope to get to the important problems having to do with how the universe began, how it evolved and so forth, which we really only study now with optical instruments or electromagnetic waves. And early in the universe, those were blocked because basically it wasn't transparent, so the photons couldn't get out when everything was too dense.

Speaker 3

01:34:19

What do you think, sorry on this tangent, what do you think an understanding of gravitational waves from earlier in the universe can help us understand about the Big Bang and all that kind of stuff?

Speaker 2

01:34:28

Yeah, yeah, that's,

Speaker 3

01:34:30

So. But it's a non, it's another perspective on the thing. Is there some insights you think could be revealed just to help a layman understand?

Speaker 2

01:34:41

Sure. First, we don't understand, we use the word Big Bang, we don't understand the physics of what the Big Bang itself was. So, I think my, and in the early stage there were particles, and there was a huge amount of gravity and mass being made. So, I'll say 2 things.

Speaker 2

01:35:06

1 is, how did it all start? How did it happen? And I'll give you at least 1 example that we don't understand, but we should understand. We don't know why we're here.

Speaker 3

01:35:17

Yes, no, we do not.

Speaker 2

01:35:20

I don't mean it philosophically. I mean it in terms of physics, okay? Now what do I mean by that?

Speaker 2

01:35:27

If I go into my laboratory at CERN or somewhere and I collide particles together or put energy together, I make as much antimatter as matter.

Speaker 3

01:35:36

Right.

Speaker 2

01:35:37

Antimatter then annihilates matter and makes energy. So in the early universe, there you made somehow, somehow a lot of matter and antimatter, but there was an asymmetry. Somehow there was more matter and antimatter.

Speaker 2

01:35:55

The matter and antimatter annihilated each other, at least that's what we think, and there was only matter left over, and we live in a universe that we see, it's all matter. We don't have any idea, we have an ideas, but we don't have any way to understand that at the present time with the physics that we know.

Speaker 3

01:36:15

Can I ask a dumb question? Does antimatter have anything like a gravitational field to send signals? So how does this asymmetry of matter, antimatter, could be investigated or further understood by observing gravitational fields or weirdnesses in gravitational fields?

Speaker 2

01:36:37

I think that in principle, if there were, you know, anti-neutron stars instead of just neutron stars, we would see different kind of signals. But it didn't get to that. We live in a universe that we've done enough looking, because we don't see matter, antiprotons anywhere, no matter what we look at, that it's all made out of matter.

Speaker 2

01:37:01

There is no antimatter except when we go in our laboratories. So, but when we go in our laboratories, we make as much antimatter as matter. So there's something about the early universe that made this asymmetry. So we can't even explain why we're here, that's what I meant.

Speaker 3

01:37:18

Yeah.

Speaker 2

01:37:20

Physics wise, not in terms of how we evolved and all that kind of stuff.

Speaker 3

01:37:27

So there might be inklings of the physics that gravitational waves will put down.

Speaker 2

01:37:36

So gravitational waves don't get obstructed like light. So I said light only goes to 300,000 years. So it goes back to the beginning.

Speaker 2

01:37:44

So if you could study the early universe with gravitational waves, we can't do that yet. Then, it took 400 years to be able to do that with optical, but then you can really understand the very, maybe understand the very early universe. So in terms of questions like why we're here or what the Big Bang was, we should be, we can in principle study that with gravitational waves. So to keep moving in this direction, it's a unique kind of way to understand our universe.

Speaker 3

01:38:20

So you think there's more Nobel Prize level ideas to be discovered in relation to gravitational waves?

Speaker 2

01:38:25

I'd be shocked if there isn't, not even going to that, which is a very long range problem. But I think that we only see with electromagnetic waves 4% of what's out there. There must be, we looked for things that we knew should be there.

Speaker 2

01:38:47

There should be, I would be shocked if there wasn't physics, objects, science, and with gravity that doesn't show up in everything we do with telescopes. So I think we're just limited by not having powerful enough instruments yet to do this.

Speaker 3

01:39:10

Do you have a preference? I keep seeing this E-LISA idea.

Speaker 2

01:39:17

Yeah.

Speaker 3

01:39:19

Do you have a preference for earthbound or space-faring mechanisms for?

Speaker 2

01:39:26

They're complementary. It's a little bit like.

Speaker 3

01:39:29

A

Speaker 2

01:39:29

signal. It's completely analogous to what's been done in astronomy. Right. So, astronomy from the time of Galileo was done with visible light.

Speaker 2

01:39:40

Yeah. The big advances in astronomy in the last 50 years are because we have instruments that look at the infrared, microwave, ultraviolet, and so forth. So looking at different wavelengths has been important. Basically going into space means that we'll look at, instead of the audio band, which we look at, as we said, on the Earth's surface, we'll look at lower frequencies.

Speaker 2

01:40:05

So it's completely complementary, and it starts to be looking at different frequencies, just like we do with astronomy.

Speaker 3

01:40:14

It seems almost incredible to me, engineering-wise, just like on Earth, to send something that's kilometers across into space. Is that harder to engineer?

Speaker 2

01:40:26

It actually is a little different. It's 3 satellites separated by hundreds of thousands of kilometers. And they send a laser beam from 1 to the other.

Speaker 2

01:40:38

And if the triangle changes shape a little bit, they detect that from a passage.

Speaker 3

01:40:46

Did you say hundreds of thousands of kilometers? Yeah. Sending lasers to each other.

Speaker 3

01:40:55

Okay.

Speaker 2

01:40:56

It's just engineering.

Speaker 3

01:40:59

Is it possible though? Yes. Is it doable?

Speaker 3

01:41:02

Yes. Okay. That's just incredible, because they have to maintain, I mean, the precision here is probably, there might be some more, what is it, maybe noise is a smaller problem? I guess there's no vibration to worry about, like seismic stuff.

Speaker 3

01:41:21

So getting away from Earth, maybe you get away from-

Speaker 2

01:41:23

Yeah, those parts are easier. They don't have to measure it as accurately at low frequencies, but they have a lot of tough engineering problems. In order to detect that the gravitational waves affect things, the sensors have to be what we call free masses, just like ours, are isolated from the Earth.

Speaker 2

01:41:47

They have to isolate it from the satellite. And that's a hard problem. They have to do that pretty, not as well as we have to do it, but very well. And they've done a test mission, and the engineering seems to be, at least in principle, in hand.

Speaker 2

01:42:05

This'll be in the 2030s when it floats. 2030s?

Speaker 3

01:42:08

Yeah. This is incredible. This is incredible. Let me ask about black holes.

Speaker 3

01:42:16

Yeah. So what we're talking about is observing orbiting black holes. I saw the terminology of binary black hole systems. That's when they're dancing.

Speaker 3

01:42:32

Okay.

Speaker 2

01:42:33

They're both going around each other just like the Earth around the sun.

Speaker 3

01:42:36

Okay, is that weird that there's black holes going around each other?

Speaker 2

01:42:40

So, the finding binary systems of stars is similar to finding binary systems of-

Speaker 3

01:42:45

Of Black holes.

Speaker 2

01:42:46

Well, they were once stars. So we haven't said what a black hole is physically yet.

Speaker 3

01:42:55

Yeah, what's a black hole?

Speaker 2

01:42:56

So black hole is, first it's a mathematical concept or a physical concept, and that is a region of space, so it's simply a region of space where the curvature of space-time, meaning the gravitational field, is so strong that nothing can get out, including light. And there's light gets bent in gravitation, if the space-time is warped enough. And so even light gets bent around and stays in it.

Speaker 2

01:43:29

So that's the concept of a black hole. So it's not a, and maybe you can make, Maybe it's a concept that didn't say how they come about. And there could be different ways they come about. The ones that we are seeing, there's a...

Speaker 2

01:43:48

We're not sure. That's what we're trying to learn now is what they, but the general expectation is that they come, these black holes happen when a star dies. So what does that mean that a star dies? What happens?

Speaker 2

01:44:05

A star like our sun basically makes heat and light by fusion. It's made of... And as it burns, it burns up the hydrogen and then the helium and then slowly works its way up to the heavier and heavier elements that are in the star. And when it gets up to iron, the fusion process doesn't work anymore.

Speaker 2

01:44:30

And so the stars die and that happens to stars and then they do what's called a supernova. What happens then is that a star is a delicate balance between an outward pressure from fusion and light and burning and an inward pressure of gravity trying to pull the masses together. Once it burns itself out, it goes, and it collapses, and that's a supernova. When it collapses, all the mass that was there is in a very much smaller space.

Speaker 2

01:45:04

And if a star, if you do the calculations, if a star is big enough, that can create a strong enough gravitational field to make a black hole. Our sun won't.