Barry Barish: Gravitational Waves and the Most Precise Device Ever Built
嘉宾：Barry Barish
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The following is a conversation with Barry Barish,
a theoretical physicist at Caltech,
and the winner of the Nobel Prize in Physics
for his contributions to the LIGO detector
and the observation of gravitational waves.
LIGO, or the Laser Interferometer
Gravitational Wave Observatory,
is probably the most precise measurement device
ever built by humans.
It consists of two detectors
with four kilometer long vacuum chambers
situated 3,000 kilometers apart,
operating in unison to measure a motion
that is 10,000 times smaller than the width of a proton.
It is the smallest measurement ever attempted by science,
a measurement of gravitational waves
caused by the most violent and cataclysmic events
in the universe,
occurring over tens of millions of light years away.
To support this podcast,
please check out our sponsors in the description.
This is the Lex Friedman Podcast,
and here is my conversation with Barry Barish.
You've mentioned that you were always curious
about the physical world,
and that an early question you remember stood out
where you asked your dad,
"Why does ice float on water?"
And he couldn't answer.
And this was very surprising to you.
So you went on to learn why.
Maybe you can speak to what are some early questions
in math and physics that really sparked your curiosity?
- Yeah, that memory is
kind of something I use to illustrate
something I think that's common in science,
is that people that do science somehow have maintained,
maintained something that kids always have.
A small kid, eight years old or so,
asks you so many questions usually,
typically that you consider them pests,
tell them to stop asking so many questions.
And somehow our system manages to kill that in most people.
So in school, we make people do study and do their things,
but not to pester them by asking too many questions.
And I think, not just myself,
but I think it's typical of scientists like myself
that have somehow escaped that.
Maybe we're still children,
or maybe we somehow didn't get it beaten out of us.
But I think it's, I teach in college level,
and it's, to me, one of the biggest deficits
is the lack of curiosity, if you want,
that we've beaten out of them,
'cause I think it's an innate human quality.
- Is there some advice or insights you can give
to how to keep that flame of curiosity going?
- I think it's a problem of both parents,
and the parents should realize
that's a great quality we have,
that you're curious and that's good.
Instead, we have expressions like curiosity killed the cat.
And more, but I mean, basically,
it's not thought to be a good thing.
You get, curiosity killed the cat means
if you're too curious, you get in trouble.
- I don't like cats anyway, so maybe it's a good thing.
- Yeah, yeah, that, to me, needs to be solved,
really, in education and in homes.
That realization that there's certain human qualities
that we should try to build on and not destroy,
one of them is curiosity.
Anyway, back to me and curiosity,
I was a pest and asked a lot of questions.
My father generally could answer them at that age.
And the first one I remember that he couldn't answer
was not a very original question,
but basically that ice is made out of water,
and so why does it float on water?
And he couldn't answer it.
And it may not have been the first question,
it's the first one that I remember.
And that was the first time that I realized
that to learn and answer your own curiosity or questions,
there's various mechanisms.
In this case, it was going to the library
or asking people who know more and so forth,
but eventually you do it by what we call research.
But it's driven by,
if you're, hopefully you ask good questions,
if you ask good questions
and you have the mechanisms to solve them,
then you do what I do in life, basically.
Not necessarily physics,
and it's a great quality in humans and we should nurture it.
- Do you remember any other kind of, in high school,
maybe early college, more basic physics ideas
that sparked your curiosity
or mathematics or science in general?
- I wasn't really into science until I got to college,
to be honest with you.
But just staying with water for a minute,
I remember that I was curious
why, what happens to water?
You know, it rains and there's water in a wet pavement
and then the pavement dries out.
What happened to this water that came down?
And I didn't know that much.
And then eventually I learned in chemistry or something,
water's made out of hydrogen and oxygen.
Those are both gases,
so how the heck does it make this substance, this liquid?
(both laugh)
- Yeah, so that has to do with states of matter.
I know perhaps LIGO and the thing
for which you've gotten the Nobel Prize
and the things much of your life work
perhaps was a happy accident in some sense
in the early days,
but is there a moment where you looked up to the stars
and also the same way you wondered about water,
wondered about some of the things
that are out there in the universe?
- Oh yeah, I think everybody looks and is in awe
and is curious about what it is out there.
And as I learned more, I learned, of course,
that we don't know very much about what's there.
And the more we learn, the more we know we don't know.
I mean, we don't know what the majority
of anything is out there.
It's all what we call dark matter, dark energy.
And that's one of the big questions.
20 years when I was a student, those weren't questions.
So we even know less in a sense
the more we look.
So of course, I think that's one of the areas
that almost it's universal.
People see the sky, they see the stars
and they're beautiful and see it looks different
on different nights.
And it's a curiosity that we all have.
- What are some questions about the universe
that in the same way that you felt about the ice,
that today, you mentioned to me offline,
you're teaching a course on the frontiers of science,
frontiers of physics.
What are some questions, outside the ones
we'll probably talk about, that kind of,
yeah, fill you with, get your flame of curiosity up
and firing up, fill you with awe?
- Well, first I'm a physicist, not an astronomer.
So I'm interested in the physical phenomenon, really.
So the question of dark matter and dark energy,
which we probably won't talk about,
are recent, they're in the last 20, 30 years,
or certainly dark energy.
Dark energy is a complete puzzle.
It goes against what you will ask me about,
which is general relativity
and Einstein's general relativity.
It basically takes something that he thought was,
what he called a constant, which isn't,
and if that's even the right theory,
and it represents most of the universe.
And then we have something called dark matter,
and there's good reason to believe
it might be an exotic form of particles.
And that is something I've always worked on,
on particle accelerators and so forth.
And it's a big puzzle, what it is.
It's a bit of a cottage industry
in that there's lots and lots of searches.
But it may be a little bit like,
looking for a treasure under rocks or something.
It's hard to, we don't have really good guidance,
except that we have very, very good information
that it's pervasive and it's there.
And that it's probably particles, small,
that evidences all of those things.
But then the most logical solution doesn't seem to work,
something called supersymmetry.
- And do you think the answer could be
something very complicated?
- You know, I like to hope that,
think that most things that appear complicated
are actually simple, if you really understand them.
I think we just don't know at the present time,
and it isn't something that affects us.
It does affect, it affects how the stars
go around each other and so forth,
'cause we detect that there's missing gravity.
But it doesn't affect everyday life at all.
I tend to think and expect, maybe,
and that the answers will be simple,
we just haven't found it yet.
- Do you think those answers might change
the way we see other sources of gravity, black holes,
the way we see the parts of the universe that we do study?
- It's conceivable.
The black holes that we've found in our experiment,
§02Transcript · 10:01–20:09
and we're trying now to understand the origin of those,
it's conceivable, but not, doesn't seem the most likely
that they were primordial,
that is, they were made at the beginning.
And in that sense, they could represent
at least part of the dark matter.
So there can be connections.
Dark black holes, or how many there are,
how much of the mass they encompass
is still pretty primitive, we don't know.
- So before I talk to you more about black holes,
let me take a step back to,
I actually went to high school in Chicago,
and would go to take classes at Fermilab,
watch the buffalo and so on.
- Yeah. (laughing)
- So let me ask about, you mentioned that Enrico, for me,
was somebody who was inspiring to you
in a certain kind of way.
Why is that, can you speak to that?
- Sure.
He was amazing, actually.
He's the last, this is not the,
I'll come to the reason in a minute,
but he had a big influence on me at a young age.
But he was the last physicist of note
that was both an experimental physicist
and a theorist at the same time.
And he did two amazing things within months.
In 1933, we didn't really know what the nucleus was,
what radioactive decay was, what beta decay was,
when electrons come out of a nucleus.
And near the end of 1933,
the neutron had just been discovered,
and that meant that we knew a little bit more
about what the nucleus is,
that it's made out of neutrons and protons.
The neutron wasn't discovered till 1932.
And once we discovered that there was a neutron and proton,
and they made the nucleus,
and then there are electrons that go around,
the basic ingredients were there.
And he wrote down not only just the theory,
a theory, but a theory that lasted decades
and has only been improved on of beta decay,
that is, the radiation.
He did this, came out of nowhere,
and it was a fantastic theory.
He submitted it to "Nature" magazine,
which was the primary best place to publish even then.
And it got rejected as being too speculative.
And so he went back to his drawing board in Rome
where he was, added some to it, made it even longer,
'cause it's really a classic article,
and then published it in the local Italian journal
for physics and the German one.
At the same time, in January of 1932,
Giulio and Curie, for the first time,
saw artificial radioactivity.
This was an important discovery
because radioactivity had been discovered much earlier.
And they had X-rays, and you shouldn't be using them,
but there was radioactivity.
People knew it was useful for medicine.
But radioactive materials are hard to find,
and so it wasn't prevalent.
But if you could make them, then they had great use.
And Giulio and Curie were able to bombard aluminum
or something with alpha particles
and find that they excited something
that decayed and had some half-life and so forth,
meaning it was the artificial version,
or let's call it not a natural version,
an induced version of radioactive materials.
And Fermi somehow had the insight,
and I still can't see where he got it,
that the right way to follow that up
was not using charged particles like alphas and so forth,
but use these newly discovered neutrons
as the bombarding particle.
Seemed impossible.
They barely had been seen.
It was hard to get very many of them.
But it had the advantage that they don't,
they're not charged, so they go right into the nucleus.
And that turned out to be the experimental work
that he did that won him the Nobel Prize.
And it was the first step in fission,
discovery of fission.
And he did this two completely different things,
an experiment that was a great idea
and a tremendous implementation,
because how do you get enough neutrons?
And then he learned quickly that not only do you want
neutrons, but you want really slow ones.
He learned that experimentally,
and he learned how to make slow ones,
and then they were able to make,
go through the periodic table and make lots of particles.
He missed on fission at the moment,
but he had the basic information,
and then fission followed soon after that.
- Forgive me for not knowing,
but is the birth of the idea of bombarding neutrons,
is that an experimental idea?
Was it born out of an experiment,
he just observed something,
or is this an Einstein-style idea
where you come up from basic intuition?
- I think it took a combination,
because he realized that neutrons had a characteristic
that would allow them to go all the way into the nucleus
when we didn't really understand
what the structure was of all this.
So that took an understanding or recognition
of the physics itself of how a neutron interacts
compared to say an alpha particle
that Giulio and Curie had used.
And then he had to invent a way to have enough neutrons,
and he had a team of associates,
and he pulled it off quite quickly.
So it was pretty astounding.
- And probably, maybe you can speak to it,
his ability to put together the engineering aspects
of great experiments and doing the theory,
they probably fed each other.
I wonder, can you speak to why we don't see more of that?
Is that just really difficult to do?
- It's difficult to do, yeah.
I think in both theory and experiment,
in physics anyway,
it was conceivable if you had the right person to do it,
and no one's been able to do it since.
So I had the dream that that was
what I was gonna be like, Fermi.
- So you love both sides of it, the theory and the experiment.
- Yeah, I never liked the idea that you did experiments
without really understanding the theory,
or the theory should be related very closely to experiments.
And so I've always done experimental work
that was closely related to the theoretical ideas.
- I think I told you I'm Russian,
so I'm gonna ask some romantic questions.
But is it tragic to you that he's seen
as the architect of the nuclear age,
that some of his creations led to potentially,
some of his work has led to potentially still
the destruction of the human species,
some of the most destructive weapons?
- Yeah.
I think even more general than him,
I gave you all the virtues of curiosity a few minutes ago.
There's an interesting book
called "The Ratchet of Curiosity."
You know, a ratchet is something that goes in one direction.
And that is written by a guy who's probably a sociologist
or philosopher or something.
And he picks on this particular problem, but other ones,
and that is the danger of knowledge, basically.
You're curious, you learn something.
So it's a little bit like curiosity killed the cat.
You have to be worried about whether you can handle
new information that you get.
So in this case, the new information had to do
with really understanding nuclear physics.
And that information, maybe we didn't have
the sophistication to know how to keep it under control.
Yeah, and Fermi himself was a very apolitical person.
So he wasn't very driven by,
or at least he appears in all of his writing,
the writing of his wife,
the interactions that others had with him
as either he avoided it all or he was pretty apolitical.
I mean, he just saw the world through
kind of the lens of a scientist.
But he asked if it's tragic.
The bomb was tragic, certainly on Japan,
and he had a role in that.
So I wouldn't want it as my legacy, for example.
- I mean, but brought it to the human species
that it's the ratchet of curiosity that we,
we do stuff just to see what happens.
That curiosity, that in sort of my area
of artificial intelligence, that's been a concern.
There, on a small scale, on a silly scale,
perhaps currently, there's constantly
unintended consequences.
You create a system and you put it out there
and you have intuitions about how it will work.
You have hopes how it will work,
but you put it out there just to see what happens.
- Yeah.
- And in most cases, because artificial intelligence
is currently not super powerful,
it doesn't create large-scale negative effects.
But that same curiosity, as it progresses,
might lead to something that destroys the human species.
And the same may be true for bioengineering.
There's people that engineer viruses
to protect us from viruses, to see how do,
§03Transcript · 20:14–30:00
how close is this to mutating so it can jump to humans?
Or going, or engineering defenses against those.
And it seems exciting, and the application,
the positive applications are really exciting at this time,
but we don't think about how that runs away
in decades to come.
- Yeah, and I think it's the same idea
as this little book, "The Ratchet of Science,"
the ratchet of curiosity.
I mean, whether you pursue, take curiosity
and let artificial intelligence or machine learning
run away with having its solutions to whatever you want,
or we do it, is, I think, a similar consequence.
- I think, from what I've read about Enrico Fermi,
he became a little bit cynical about the human species
towards the end of his life,
both having observed what he observed.
- Well, he didn't write much.
I mean, he died young.
He died soon after the World War.
There was already the work by Teller
to develop the hydrogen bomb,
and I think he was a little cynical of that,
pushing it even further, and the rising tensions
between the Soviet Union and the US,
and it looked like an endless thing.
But he didn't say very much, but a little bit,
as you said, that--
- Yeah, there's a few clips to sort of maybe pick
on a bad mood, but in a sense that,
almost like a sadness, a melancholy sadness,
to a hope that waned a little bit about that,
perhaps we can do, like, this curious species
can find the way out.
- Well, especially, I think, people who worked
like he did at Los Alamos and spent years of their life
somehow had to convince themselves
that dropping these bombs would bring lasting peace.
- Yes, and it did.
- And it didn't, yeah.
- As a small interesting aside,
it'd be interesting to hear if you have opinions on this,
his name is also attached to the Fermi Paradox,
which asks if there's, you know,
with, it's a very interesting question,
which is, it does seem, if you sort of reason, basically,
that there should be a lot of alien civilizations out there
if the human species, if Earth is not that unique,
by basic, no matter the values you pick,
it's likely that there's a lot of alien civilizations
out there, and if that's the case,
why have they not at least obviously visited us
or sent us loud signals that everybody can hear?
- Fermi's quoted as saying, sitting down at lunch,
I think it was with Teller and Herb York,
who was kind of one of the fathers of the atomic bomb,
and he sat down and he says something like,
"Where are they?"
- Yeah.
- Which meant, where are these other,
and then he did some numerology where he calculated,
you know, how many, what they knew about how many
galaxies there are and how many stars
and how many planets there are like the Earth
and blah, blah, blah.
That's been done much better by somebody named Drake,
and so people usually refer to the,
I don't know whether it's called the Drake formula
or something, but it has the same conclusion.
The conclusion is it would be a miracle
if there weren't other, you know,
the statistics are so high that how can we be singular
and separate?
That, so probably there is,
well, there's almost certainly life somewhere.
Maybe there was even life on Mars a while back,
but intelligent life, probably white,
or we saw, so, you know, the statistics say that.
Communicating with us, I think that it's harder
than people think.
We might not know the right way to expect the communication,
but all the communication that we know about,
travels at the speed of light,
and we don't think anything can go faster
in the speed of light.
That limits the problem quite a bit,
and it makes it difficult to have any
back and forth communication.
You could send signals like we try to or look for,
but to have any communication, it's pretty hard
when it has to be close enough that the speed of light
would mean we could communicate with each other,
and I think, and we didn't even understand that.
I mean, we're an advanced civilization,
but we didn't even understand that
a little more than 100 years ago.
So, are we just not advanced enough, maybe,
to know something about that's the speed of light?
Maybe there's some other way to communicate
that isn't based on electromagnetism.
I don't know.
Gravity seems to be also have the same speed.
That was a principle that Einstein had,
and something we've measured, actually.
- So, is it possible, I mean,
so we'll talk about gravitational waves,
and in some sense, there's a brainstorming going on,
which is like, how do we detect the signal?
Like, what would a signal look like,
and how would we detect it?
And that's true for gravitational waves.
That's true for basically any physics phenomena.
You have to predict that that signal should exist.
You have to have some kind of theory
and model why that signal should exist.
I mean, is it possible that aliens
are communicating with us via gravity?
Like, why not?
- Well, yeah, it's true, why not?
For us, it's very hard to detect
these gravitational effects.
They have to come from something pretty,
that has a lot of gravity, like black holes.
But we're pretty primitive at this stage.
There's very reputable physicists
that look for a fifth force,
one that we haven't found yet.
Maybe it's the key.
- What would that look like?
What would a fifth force of physics look like, exactly?
- Well, usually, they think it's probably a long-range,
longer-range force than we have now.
But there are reputable colleagues of mine
that spend their life looking for a fifth force.
- So, longer-range than gravity?
Is it like super long?
- It doesn't fall off like one over r-squared,
but maybe separately.
Gravity, Newton taught us, goes like inversely,
one over the square of the distance apart you are.
So, it falls pretty fast.
- That's okay.
So, now we have a theory of what consciousness is.
It's just the fifth force of physics.
- Yeah.
- There we go.
That's a good hypothesis.
Speaking of gravity, what are gravitational waves?
This may be start from the basics.
- We learned gravity from Newton, right?
You and you were young.
You were told that if you jumped up,
the Earth pulled you down.
And when the apple falls out of the tree,
the Earth pulls it down.
And maybe you even asked your teacher why,
but most of us accepted that.
That was Newton's picture,
the apple falling out of the tree.
But Newton's theory never told you
why the apple was attracted to the Earth.
That was missing in Newton's theory.
Newton's theory also,
Newton recognized at least one of the two problems,
I'll tell you.
One of them is, there's more than those,
but one is, why does the Earth,
what's the mechanism by which the Earth pulls the apple
or holds the moon when it goes around, whatever it is?
That's not explained by Newton,
even though he has the most successful theory of physics ever
went 200 and some years with nobody ever seeing a violation.
- But he accurately describes the movement of an object
falling down to Earth, but he's not answering why that,
what's, 'cause it's a distance, right?
- He gives a formula, which it's a product
of the Earth's mass, the apple's mass,
inversely proportional to the square
of the distance between,
and then the strength he called capital G,
the strength he couldn't determine,
but it was determined 100 years later.
But no one ever saw a violation of this
until a possible violation, which Einstein fixed,
which was very small,
that has to do with Mercury going around the sun,
the orbit being slightly wrong,
if you calculate it by Newton's theory.
But so, like most theories then in physics,
you can have a wonderful one like Newton's theory,
it isn't wrong, but you have to have an improvement on it
to answer things that it can't answer.
And in this case, Einstein's theory is the next step.
We don't know if it's anything like a final theory
or even the only way to formulate it either,
but he formulated this theory, which he released in 1915.
He took 10 years to develop it,
even though in 1905, he solved three or four
of the most important problems in physics
in a matter of months,
§04Transcript · 30:01–39:38
and then he spent 10 years on this problem
before he let it out, and this is called general relativity,
it's a new theory of gravity, 1915.
In 1916, Einstein wrote a little paper
where he did not do some fancy derivation,
instead he did, what I would call it,
he used his intuition, which he was very good at too,
and that is he noticed that if he wrote the formulas
for general relativity in a particular way,
they looked a lot like the formulas
for electricity and magnetism.
Being Einstein, he then took the leap
that electricity and magnetism,
we discovered only 20 years before that,
in the 1880s, have waves.
Of course, that's light and electromagnetic waves,
radio waves, everything else.
So he said if the formulas look similar,
then gravity probably has waves too.
- That's such a big leap, by the way,
I mean, maybe you can correct me,
but that just seems like a heck of a leap.
- Yeah, and it was considered to be a heck of a leap.
So first, that paper was, except for this intuition,
was poorly written, had a serious mistake,
it had a factor of two wrong in the strength of gravity,
which meant if we used those formulas, we would,
and two years later, he wrote a second paper
and in that paper, it turns out to be important for us
because in that paper, he not only fixed his factor
of two mistake, which he never admitted,
he just wrote it, fixed it like he always did,
and then he told us how you make gravitational waves,
what makes gravitational waves.
And you might recall in electromagnetism,
we make electromagnetic waves in a simple way,
you take a plus charge and minus charge,
you oscillate like this
and that makes electromagnetic waves.
And a physicist named Hertz made a receiver
that could detect the waves and put it in the next room.
He saw them and moved forward and backward
and saw that it was wave-like.
So Einstein said it won't be a dipole like that,
it'll be a four-pole thing,
and that's what, it's called a quadrupole moment
that gives the gravitational wave.
So he saw that again by insight, not by derivation.
That set the table for what you needed to do to do it.
At the same time, in the same year,
Schwarzschild, not Einstein,
said there were things called black holes.
So it's interesting that that came the same.
- So what year was that?
- 1915.
- It was in parallel.
I should probably know this,
but did Einstein not have an intuition
that there should be such things as black holes?
- That came from Schwarzschild.
- Oh, interesting.
- Yeah, so Schwarzschild,
who was a German theoretical physicist,
he got killed in the war, I think,
in the First World War two years later or so.
He's the one that proposed black holes,
that there were black holes.
- That feels like a natural conclusion
of general relativity, no?
Or is that not?
- Well, it may seem like it,
but I don't know about a natural conclusion.
It's a result of curved space-time, though.
- Right, but it's such a weird result
that you might have to, it's a special--
- Yeah, it's a special case.
So I don't know.
Anyway, Einstein then,
an interesting part of the story
is that Einstein then left the problem.
Most physicists, because it really wasn't derived,
he just made this, didn't pick up on it,
or general relativity much,
because quantum mechanics became the thing in physics.
And Einstein only picked up this problem again
after he immigrated to the US.
So he came to the US in 1932,
and I think in 1934 or '35,
he was working with another physicist called Rosen,
who he did several important works with,
and they revisited the question.
And they had a problem that most of us as students
always had, that studied general relativity.
General relativity's really hard
because it's four-dimensional instead of three-dimensional.
And if you don't set it up right,
you get infinities, which don't belong there.
We call them coordinate singularities as a name.
But if you get these infinities,
you don't get the answers you want.
And he was trying to derive now,
general relativity from general relativity,
gravitational waves.
And in doing it, he kept getting these infinities.
And so he wrote a paper with Rosen
that he submitted to our most important journal,
Physical Review Letters.
And that when it was submitted to Physical Review Letters,
it was entitled, "Do Gravitational Waves Exist?"
A very funny title to write
20 years after he proposed they exist.
But it's because he had found these singularities,
these infinities.
And so the editor at that time,
and part of it that I don't know is peer review.
We live and die by peer review as scientists
send our stuff out.
We don't know when peer review actually started
or what peer review Einstein ever experienced
before this time.
But the editor of Physical Review sent this out for review.
He had a choice.
He could take any article and just accept it.
He could reject it or he could send it for review.
- Right, I believe the editors
used to have much more power.
- Yeah, yeah.
And he was a young man, his name was Tate.
And he ended up being editor for years.
But so he sent this for review
to a theoretical physicist named Robertson
who was also in this field of general relativity
who happened to be on sabbatical at that moment at Caltech.
Otherwise his institution was Princeton
where Einstein was.
And he saw that the way they set up the problem,
the infinities were like I make it as a student
'cause if you don't set it up right in general relativity,
you get these infinities.
And so he reviewed the article and gave an illustration
that if they set it up
on what are called cylindrical coordinates,
these infinities went away.
The editor of Physical Review
was obviously intimidated by Einstein.
He wrote this really not a letter back
like I would get saying,
you're screwed up in your paper.
Instead, it was kind of,
what do you think of the comments of our referee?
Einstein wrote back, it's a well-documented letter,
wrote back a letter to Physical Review
saying I didn't send you the paper
to send it to one of your so-called experts,
I sent it to you to publish.
I withdraw the paper.
And he never published again in that journal.
That was 1936.
Instead, he rewrote it
with the fixes that were made,
changed the title and published it
in what was called the Franklin Review
which is the Franklin Institute in Philadelphia
which is Benjamin Franklin Institute
which doesn't have a journal now but did at that time.
So the article is published.
It's the last time he ever wrote about it.
It remained controversial.
So it wasn't until close to 1960, 1958
where there was a conference
that brought together the experts in general relativity
to try to sort out whether there was
whether it was true
that there were gravitational waves or not.
And there was a very nice derivation
by a British theorist from the heart of the theory
that gets gravitational waves.
And that was number one.
The second thing that happened at that meeting
is Richard Feynman was there.
And Feynman said, well, if there's typical Feynman,
if there's gravitational waves,
they need to be able to do something.
Otherwise, they don't exist.
So they have to be able to transfer energy.
So he made a idea of a Gedanken experiment
that is just a bar with a couple of rings on it.
And then if a gravitational wave goes through it,
distorts the bar.
And that creates friction on these little rings.
And that's heat and that's energy.
So that meant--
- Is that a good idea?
It sounds like a good idea.
- Yeah, it means that he showed
that with the distortion of space-time,
you could transfer energy just by this little idea.
And it was shown theoretically.
So at that point, it was believed theoretically
then by people that gravitational waves should exist.
§05Transcript · 39:43–48:02
- No, we should be able to detect them.
- We should be able to detect them,
except that they're very, very small.
- So what kind of, there's a bunch of questions here,
but what kind of events would generate gravitational waves?
- You have to have this, what I call quadrupole moment.
That comes about if I have, for example,
two objects that go around each other like this,
like the Earth around the Sun or the Moon around the Earth.
Or in our case, it turns out to be two black holes
going around each other like this.
- So how's that different
than basic oscillation back and forth?
Is it just more common in nature to have--
- Oscillation is a dipole moment.
- So it has to be in three-dimensional space
and kind of oscillation.
- So you have to have something that's three-dimensional
that'll give what I call a quadrupole moment
that's just built into this.
- And luckily in nature, you have stuff--
- And luckily, things exist.
And it is luckily because the effect is so small
that you could say, look, I can take a barbell
and spin it, right, and detect the gravitational waves.
But unfortunately, no matter how much I spin it,
how fast I spin it-- - Oh, interesting.
- So I know how to make gravitational waves,
but they're so weak, I can't detect them.
So we have to take something that's stronger
than I can make.
Otherwise, we would do what Hertz did
for electromagnetic waves, go in our lab,
take a barbell, put it on something, spin it.
- Can I ask a dumb question?
So a single object that's weirdly shaped,
does that generate gravitational waves?
So if it's rotating?
- Sure, it-- - But it's just
much weaker signal. - It's weaker.
Well, we didn't know what the strongest signal would be
that we would see.
We targeted seeing something called neutron stars,
actually, because black holes,
we don't know very much about.
It turned out we were a little bit lucky.
There was a stronger source, which was the black holes.
- Well, another ridiculous question.
So you say waves.
What does a wave mean?
Like the most ridiculous version of that question is,
what does it feel like to ride a wave
as you get closer to the source?
Or experience it?
- Well, if you experience a wave,
imagine that this is what happens to you.
I don't know what you mean by getting close.
It comes to you.
So it's like this light wave or something
that comes through you.
So when the light hits you, it makes your eyes detect it.
I flashed it.
What does this do?
It's like going to the amusement park,
and they have these mirrors.
You look in this mirror, and you look short and fat,
and the one next to you makes you tall and thin, okay?
Imagine that you went back and forth
between those two mirrors once a second.
That would be a gravitational wave
with a period of once a second.
If you did it 60 times a second, go back and forth.
And then that's all that happens.
It makes you taller and shorter and fatter back and forth
as it goes through you
at the frequency of the gravitational wave.
So the frequencies that we detect
are higher than one a second, but that's the idea.
So, and the amount is small.
- Amount is small, but if you're closer
to the source of the wave, is it the same amount?
- Yeah, it doesn't dissipate.
- It doesn't dissipate.
Okay, so it's not that fun of an amusement ride.
- Well, it does dissipate, but it doesn't,
it doesn't, it's just, it's proportional to the distance.
- Right, it's not--
- It's not a big power or something.
- Gotcha, so, but it would be a fun ride
if you get a little bit closer, or a lot closer.
I mean, like, I wonder what the,
okay, this is a ridiculous question, but I have you here.
(laughs)
Like, the getting fatter and taller,
I mean, that experience, for some reason,
that's mind-blowing to me,
'cause it brings the distortion of space-time to you.
I mean, space-time is being morphed, right?
Like, this is a wave. - That's right.
- That, how, that's so weird.
- And we're in space, so we're affected by it.
- Yeah, we're in space, and now it's moving.
I don't know what to do with it.
- I mean, does it, okay.
How much do you think about
the philosophical implications of general relativity?
Like, that we're in space-time,
and it can be bent by gravity?
Like, is that just what it is?
Are we supposed to be okay with this?
'Cause, like, Newton, even Newton is a little weird, right?
But that at least, like, makes sense.
That's our physical world.
You know, when an apple falls, it makes sense.
But, like, the fact that entirety
of the space-time we're in can bend.
- Well-- - That's, that's,
that's really mind-blowing.
- Well, let me make another analogy.
- This is a therapy session for me at this point.
- Yeah, right, another analogy.
- Thank you.
- So, imagine you have a trampoline.
- Yes.
- Okay.
What happens if you put a marble on a trampoline?
Doesn't do anything, right?
- No.
- Just sit. - Maybe a little bit,
but not much.
- Yeah, I mean, just if I drop it,
it's not gonna go anywhere.
Now, imagine I put a bowling ball
at the center of the trampoline.
Now, I come up to the trampoline,
and I put a marble on, what happens?
- It'll roll towards the bowling ball.
- All right, so what's happened is the presence
of this massive object distorted the space
that the trampoline did.
This is the same thing that happens
to the presence of the earth, the earth and the apple.
The presence of the earth affects the space around it,
just like the bowling ball on the trampoline.
- Yeah, this doesn't make me feel better.
I'm referring from the perspective of an ant
walking around on that trampoline.
Then some guy just dropped a ball,
and not only dropped a ball, right?
It's not just dropping a bowling ball.
It's making the ball go up and down,
or doing some kind of oscillation thing,
where it's like waves.
And that's so fundamentally different
from the experience on being on flatland
and walking around and just finding
delicious sweet things as ant does.
And it just feels like, to me,
from a human experience perspective,
completely, it's humbling.
It's truly humbling.
- It's humbling, but we see that kind of phenomenon
all the time.
Let me give you another example.
Imagine that you walk up to a still pond.
- Yes.
- Okay?
Now I throw, you throw a rock in it, what happens?
The rock goes in, sinks to the bottom, fine,
and these little ripples go out, and they travel out.
That's exactly what happens.
I mean, there's a disturbance, which is these safe,
the bowling ball, or black holes,
and then the ripples, they go out in the water.
They're not, they don't have any,
they don't have the rock, any pieces of the rock.
- You see, the thing is, I guess,
what's not disturbing about that is it's a,
I mean, it's a, I guess, a flat, two-dimensional surface
that's being disturbed.
Like, for a three-dimensional surface,
three-dimensional space to be disturbed feels weird.
- It's even worse.
It's four-dimensional, because it's space and time.
- Yeah.
- So that's why you need Einstein,
is to make it four-dimensional.
- To make it okay?
- No, to make it.
- To make it four-dimensional?
- Yeah, to take the same phenomenon
and look at it in all of space and time.
Anyway, luckily for you and I and all of us,
the amount of distortion is incredibly small.
So it turns out that if you think of space itself,
now this is gonna blow your mind too,
if you think of space as being like a material,
like this table, it's very stiff.
You know, we have materials that are very pliable,
materials that are very stiff.
§06Transcript · 48:03–57:23
So space itself is very stiff.
So when gravitational waves come through it,
luckily for us, it doesn't distort it so much
that it affects our ordinary life very much.
- No, I mean, that's great.
That's great, I thought there was something bad coming.
No, this is great. - No, not bad.
- That's great news.
So I mean, perhaps we evolved as life on Earth
to be such that for us, this particular set
of effects of gravitational waves is not that significant.
Maybe that's why-- - It is.
You probably used this effect today or yesterday.
So it's pervasive.
Well-- - You mean gravity
or the way, or external?
'Cause I only-- - Curvature of space
and time. - Curvature of space, how?
I only care personally as a human, right?
The gravity of Earth.
- But you use it every day almost.
- Oh, it's curving. - Because, no, no, no.
It's in this thing.
Every time it tells you where you are.
How does it tell you where you are?
It tells you where you are because we have 24 satellites
or some number that are going around in space
and it asks how long it takes the being
to go to the satellite and come back the signal
to different ones and then it triangulates
and tells you where you are.
And then if you go down the road,
it tells you where you are.
Do you know that if you did that with the satellites
and you didn't use Einstein's equations--
- Oh, no, you wouldn't-- - You won't get
the right answer, that's right.
And in fact, if you take a road that's say 10 meters wide,
I've done these numbers, and you ask how long
you'd stay on the road if you didn't make the correction.
For general relativity, this thing you're poo-pooing,
'cause you're using every day, you'd go off the road
a minute. - You'd go off the road.
Well, actually, that might be my problem.
- So you use it, so don't poo-poo it.
- Well, I think I'm using an Androids,
and maybe, and the GPS doesn't work that well,
so maybe I'm using Newton's physics,
so I need to upgrade to general relativity.
So, gravitational waves and Einstein had,
wait, Feynman really does have a part in this story?
Was that one of the first kind of experimental
proposed detect gravitational waves?
- Well, he did what we call a Godunkin experiment,
that's a thought experiment, okay, not a real experiment.
But then, after that, then people believe
gravitational waves must exist.
You can kind of calculate how big they are, there's tiny.
And so, people started searching.
The first idea that was used was Feynman's idea,
oh, a variant of it.
And it was to take a great big, huge bar of aluminum,
and then put around, and it's made like a cylinder,
and then put around it some very, very sensitive detectors
so that if a gravitational wave happened to go through it,
it would go (mimics electric shock)
and you'd detect the extra strain that was there.
And that was this method that was used until we came along.
It wasn't a very good method to use.
- And what was the, so we're talking about
a pretty weak signal here.
- Yeah, that's why that method didn't work.
- So what, can you tell the story of figuring out
what kind of method would be able to detect
this very weak signal of gravitational waves?
- So, remembering what happens when you go
to the amusement park, that it's gonna do something like
stretch this way and squash that way,
squash this way and stretch this way.
We do have an instrument that can detect that kind of thing.
It's called an interferometer.
And what it does is it just basically takes usually light,
and the two directions that we're talking about,
you send light down one direction
and the perpendicular direction.
And if nothing changes, it takes the same,
and the arms are the same length.
It just goes down, bounces back.
And if you invert one compared to the other, they cancel.
So there's nothing happens.
But if it's like the amusement park
and one of the arms got, you know, it got shorter and fatter
so it took longer to go horizontally
than it did to go vertically.
Then when they come back, when the light comes back,
that comes back somewhat out of time.
And that basically is the scheme.
The only problem is that that's not done very accurately
in general, and we had to do it extremely accurately.
- So what's the difficulty of doing so accurately?
- Okay, so the measurement that we have to do
is a distortion in time.
How big is it?
One, it's a distortion that's one part in 10 to the 21.
That's 21 zeros and a one.
Okay? - Wow.
And so this is like a delay in the thing coming back?
- It's one of them coming back after the other one,
but the difference is just one part in 10 to the 21.
So for that reason, we make it big.
Let the arms be long.
Okay, so one part in 10 to the 21.
In our case, it's kilometers long.
So we have an instrument that's like kilometers
in one direction, kilometers in the other.
- How many kilometers are we talking about?
Four kilometers?
- Four kilometers in each direction.
If you take then one part in 10 to the 21,
we're talking about measuring something
to 10 to the minus 18 meters.
(Lex laughing)
- Okay.
- Now to tell you how small that is,
the proton thing we're made of,
which you can't go and grab so easily,
is 10 to the minus 15 meters.
So this is one 1,000th the size of a proton.
That's the size of the effect.
Einstein himself didn't think this could be measured.
Have you ever seen?
Actually, he said that,
but that's because he didn't anticipate modern lasers
and techniques that we developed.
- Okay, so maybe can you tell me a little bit
what you're referring to as LIGO,
the Laser Interferometer Gravitational-Wave Observatory.
What is LIGO?
Can you just elaborate kind of the big picture view here
before I ask you specific questions about it?
- Yeah, so in the same idea that I just said,
we have two long vacuum pipes,
10 to four kilometers long, okay?
We start with a laser beam and we divide the beam
going down the two arms,
and we have a mirror at the other end,
reflects it back.
It's more subtle, but we bring it back.
If there's no distortion in space-time
and the lengths are exactly the same,
which we calibrate them to be,
then when it comes back,
if we just invert one signal compared to the other,
they'll just cancel.
So we see nothing, okay?
But if one arm got a little bit longer than the other,
then they don't come back at exactly the same time.
They don't exactly cancel.
That's what we measure.
So to give a number to it,
we have to do that to,
we have the change of length
to be able to do this 10 to the minus 18 meters
to one part in 10 to the 12th.
And that was the big experimental challenge
that required a lot of innovation to be able to do.
- You gave a lot of credit to, I think,
Caltech and MIT for some of the technical developments
within this project.
Is there some interesting things you can speak to
at the low level of some cool stuff that had to be solved?
Like what are we talking?
I'm a software engineer, so all of this,
I have so much more respect for everything done here
than anything I've ever done.
So it's just code.
- So I'll give you an example of doing
mechanical engineering at a better,
at a basically mechanical engineering and geology
and maybe at a level.
So what's the problem?
The problem is the following,
that I've given you this picture of an instrument
that by some magic, I can make good enough
to measure this very short distance.
But then I put it down here, it won't work.
And the reason it doesn't work
is that the earth itself is moving all over the place
all the time.
You don't realize it, it seems pretty good to you.
- I get it.
- But it's moving all the time.
So somehow it's moving so much that we can't deal with it.
We happen to be trying to do the experiment here on earth,
but we can't deal with it.
So we have to make the instrument isolated from the earth.
- Oh no.
- At the frequencies we're at, we've got to float it.
That's a mechanical, that's an engineering problem,
not a physics problem.
§07Transcript · 57:24–1:06:49
- So when you actually, like we're doing,
we're having a conversation on a podcast right now,
there's, and people who record music work with this,
how to create an isolated room.
And they usually build a room within a room,
but that's still not isolated.
In fact, they say it's impossible to truly isolate
from sound, from noise and stuff like that.
But that's like one step of millions that you took
is building a room inside a room.
You basically have to isolate all.
- Now this is actually an easier problem.
It's just have to do it really well.
So making a clean room is really a tough problem
because you have to put a room inside a room.
You have to, this is really simple engineering, our physics.
Okay, so what do you have to do?
How do you isolate yourself from the earth?
First, we work at, we're not looking at all frequencies
for gravitational waves.
We're looking at particular frequencies
that you can deal with here on earth.
So what frequencies would those be?
You were just talking about frequencies.
- I mean, I don't-- - We know by evolution.
Our bodies know, it's the audio band, okay?
The reason our ears work where they work
is that's where the earth isn't going,
making too much noise.
- Okay, so the reason our ears work the way they work
is 'cause this is where it's quiet.
- That's right.
So if you go to one hertz instead of 10 hertz,
it's the earth is really moving around.
So somehow we live in a, what we call the audio band.
It's tens of hertz to thousands of hertz.
That's where we live, okay?
If we're gonna do an experiment on the earth--
- Might as well do it in the-- - It's the same frequency.
That's where the earth is the quietest.
So we have to work in that frequency.
So we're not looking at all frequencies, okay?
So the solution for the shaking of the earth
to get rid of it is pretty mundane.
If we do the same thing that you do
to make your car drive smoothly down the road.
So what happens when your car goes over a bump?
Early cars did that, they bounced.
Okay, but you don't feel that in your car.
So what happened to that energy?
You can't just disappear energy.
So we have these things called shock absorbers in the car.
What they do is they absorb,
they take the thing that went like that
and they basically can't get rid of the energy
but they move it to very, very low frequency.
So what you feel isn't, you feel it go smoothly, okay?
All right, so we also work at this frequency.
So we basically, why don't we have to do anything
other than shock absorbers?
So we made the world's fanciest shock absorbers, okay?
Not just like in your car where there's one layer of them.
They're just the right squishiness and so forth.
They're better than what's in the cars.
And we have four layers of it.
So whatever shakes and gets through the first layer,
we treat it in a second, third, fourth layer.
- So it's a mechanical engineering problem.
- Yeah, that's what I said.
So it's a real--
- There's no weird tricks to it
like a chemistry type thing or--
- No, no, just well, the right squishiness,
you need the right material inside.
And ours look like little springs, but they're--
- Springs, they're springs?
So like legitimately like shock absorbers?
- Yeah.
- What?
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.
- Just mechanical engineering, this is hilarious.
- But 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 one, and that is to get rid of noise.
You've probably noise, which is you don't like.
And that's the same principle
that's in these little Bose earphones.
- Noise canceling?
- 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 'cause it's just the same
over and over again, they cancel it.
And when the stewardess comes and asks you
whether you want coffee or tea or a drink or something,
you hear her fine 'cause she's not ambient,
she's a signal, so.
- Are we talking about active canceling?
Like where the actual-- - Active canceling.
- So-- - This is, okay.
- So another-- - Don't tell me
you have active canceling on this.
- Yeah, yeah. - Besides the shock absorbers.
- So inside this array of shock absorbers,
you asked for some interesting--
- This is awesome. (laughs)
- So inside this, it's harder than the earphone problem,
but it's just engineering.
We have to see, measure not just
that the engines 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.
- This is awesome.
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.
- Yeah. - What--
- If it all works right.
And so how much do we reduce the shaking of the earth?
- I mean-- - One part in 10 to the 12th.
- One part in 10-- - So what gets through us
is one part in 10 to the 12th.
That's pretty big reduction.
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 ask you a weird question here?
You make it very poetically and humorously.
You're saying it's just a mechanical engineering problem,
but is this one of the biggest precision
mechanical engineering efforts ever?
I mean, this seems exceptionally difficult.
- 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.
- I wonder what listening to Led Zeppelin sounds
on this thing, 'cause it's so isolated.
I mean, this is like, I don't know.
- No background noise. - No back, 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 this was possible?
- I did.
I didn't know that we needed,
for sure that we needed active when we started.
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 also expensive.
Doing what I told you is not cheap.
So it was kind of controversial.
It was funded by the National Science Foundation.
- Can you just linger on this just for a little longer?
The actuator thing, the active canceling.
Do you remember like little experiments
that were done along the way to prove to the team,
to themselves that this is even possible?
So from our, 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.
Because like, this is another level of precision
that I can't even, 'cause robots are a mess.
And this is basically one of the most precise robots ever.
Right, so like, is there,
do you remember any like small-scale experiments
that were done that just made this as possible?
- 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.
- Okay. (laughs)
Humans are just ape descendants, I gotcha.
I gotcha.
Is there any video of this?
§08Transcript · 1:06:51–1:17:01
Like some kind of educational purpose visualizations
of this active canceling?
- I don't think so.
- I mean, does this live on?
- Well, we worked for parts of it, for the active canceling,
we worked for the instruments,
for the sensor and instruments,
we worked with a small company near where you are,
'cause it was our MIT people that got them,
that were interested in the problem
because they thought they might be able to commercialize it
for making staple 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.
- 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?
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?
- I think the one 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're not doing well enough,
you have to keep making it better somehow.
But this whole huge instrument has to be in vacuum.
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 four meter long sealed vacuum system?
It has to be made out of--
- Four kilometers long.
- Four kilometers long, would I say something else?
- Meters.
- Four kilometers long.
- Big difference.
- Yeah, and so, but to make it, yeah,
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.
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.
- So you might not actually even know that there's a leak
and it will be affecting--
- 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.
- What's the difference between a high vacuum and a vacuum?
What is high vacuum?
That's like some delta close to vacuum?
Is it some threshold?
- Well, there's a unit, high vacuum is when the vacuum
and the units that are used, which are TORs,
there's 10 to the minus nine.
- Gotcha.
- High vacuum is usually used in small places.
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.
- 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.
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 one 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.
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.
- 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.
And 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 two black holes, we weren't here.
We weren't even close to being here.
- And we're both developing slowly.
- There were single, yeah, we were going from single cell
to multi-cell life at that point.
- All to meet up at this point.
- Yeah.
- Wow, that's like, that's almost romantic.
- It is.
- Okay, so on the human side of things,
it's kind of fascinating 'cause you're talking about
over a thousand people team for LIGO.
- Yeah.
- You 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.
You had this funny example, I forget where,
where in publishing a paper, you have to all agree
on like 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,
how, what does it take to lead this kind of team?
- Okay, I think the general idea is one we all know.
You wanna get where the sum of something
is more than the individual parts is what we say, right?
- Yeah.
- So that's what you're trying to achieve.
- Yes.
- Okay, 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.
- Why?
Because they overlap.
So you don't have individual things that,
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.
We know that's very common.
People use that expression everywhere.
And it's the expression that has to be kind of 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 kind of in terms of the process.
So that's the goal that you have to have is to achieve that.
And that means that you have to realize parts
of what you're trying to do that require,
not that one person couldn't do it.
It requires the combined talents to be able to do something
that neither of them could do themselves.
And we have a lot of that kind of thing.
And I think, I mean, build into some
of the examples that I gave you.
And so how do you then, so the key almost
in anything you do is the people themselves, right?
So in our case, the first and most important was to attract,
to spend years of their life on this,
and 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.
- 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?
- Oh, that's, the human problem's always the hardest.
And so 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.
We need a certain kind of laser.
So the kind of laser that we used,
there were three different institutions in the world
that had the experts that do this,
maybe in competition with each other.
So we got all three to join together and work with us
to work on this, as an example.
So that you had, and 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.
These are engineers that do lasers,
§09Transcript · 1:17:03–1:26:53
and they're part of our laser physicists.
- 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?
- It's a long story.
Unfortunately, this is a part that we started--
- Failures along the way kind of thing, or what?
- All failures, that's all, it's built into it.
- Okay.
- If you're not--
- Just mechanical engineering.
(both laughing)
- 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,
and so it's built on failures.
But anyway, we did, before MEVE,
and 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 five years to build it.
So by 1999, we had built the basic unit.
It did not have active seismic isolation at that stage.
It 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.
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.
We would run it, looking for gravitational waves for months,
learn what limited us, fix it for months,
and 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,
and we almost instantly saw this first collision
of two black holes.
And then we went through a process of,
do we believe what we've seen?
- Yeah, I think you're one of the people
that went through that process.
Sounds like some people immediately believed it.
- Yeah.
- And then you were like, "It's disgusting."
- 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--
- It's amazing.
- 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 showed next to it the calculations
of Einstein's equations, and it looks just like
what we detected.
- Wow.
- And we did it in two different detectors
halfway across the US, so it was pretty convincing.
But you don't wanna fool yourself.
So we had, being a scientist, we had, 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 looked like this.
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.
- Cybersecurity question.
- Yeah, even though we're not on the internet.
- Yeah, no, it can be physical access too.
Yeah, that's fascinating.
It's fascinating that you would think about that.
I mean, not enough.
I mean, 'cause it matches prediction,
so the chances of it actually being manipulated
is very, very low, but nevertheless.
- We still could have disgruntled all the graduate students
who had worked with us earlier that--
- Who want you to, 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 yourselves officially.
- Within a month, we convinced ourselves.
We kept 1,000 collaborators quiet during that time.
Then we spent another--
- That's funny.
- 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 two black holes and what it was.
- The fact that 1,000 collaborators were quiet
is a really strong indication
that this is a really close-knit team.
- Yeah, and they're around the world.
- Well, either strong-knit or tight-knit
or a strong dictatorship or something.
- Yeah, either fear or love.
You can rule by fear or love.
- Yeah, right.
- You can go back to Machu Belly.
All right, well, this, I mean,
this is really exciting that that was,
that's a success story 'cause it didn't have
to be a success story, right?
I mean, eventually, perhaps you could say it'll be an event,
but it could have taken it over a century to get there.
- Oh, yeah, yeah.
It's, and it's only downhill now, kind of.
(both laughing)
- What do you mean it's only,
you mean with gravitational waves?
- 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 fixing,
we're adding features where it'll probably be,
when we turn back on next year,
it'll probably be every one every couple of days,
and they're not all the same.
So it's learning about what's out there in gravity
instead of just optics.
And so 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 the, another,
a really important discovery that was made before ours
was what's called the Higgs boson,
made on the big accelerator at CERN.
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.
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,
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 kind 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,
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 since 2015, when we saw the first one,
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.
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 four 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.
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 gonna be more and more that we can do
as we can make better and better instruments,
§10Transcript · 1:26:55–1:36:54
because as I say, it's not limited by-
- Physics. - Picking it out of others.
Yeah, it's not limited by the physics.
- 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-
- As long as it's not limited by physics,
yeah, they'll do it.
- So you, two 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?
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.
Maybe I'm romanticizing engineering.
But I guess I wanna ask,
how important is the Nobel Prize in all of this?
- 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 one a year.
So there's been 200 physicists
who have won the Nobel Prize since 1900.
And so that's, you know,
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.
I mean, why the Nobel Prize for a guy
that made dynamite and stuff is what it is,
it's a long story.
But it's the one day a year where actually the science
that people have done is all over the world and so forth.
Forget about the people again.
It is really good for science.
- Celebrating science.
- It celebrates science for several days,
different fields, chemistry, medicine, and so forth.
And everybody doesn't understand everything about these.
They're generally fairly abstract,
but then it's on the front page
of newspapers around the world.
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.
It's otherwise, you know,
I have a certain celebrity that I didn't have before.
- 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 in everything we do.
- Well, it has a little bit more.
One 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.
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.
- Yes. - 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.
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.
- Yeah, this is very true.
You're like the celebrities who talk.
Celebrity has power.
- Celebrity has power.
- And that's-- - And that's a good thing.
- That's a good thing, yeah.
- 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 that's the other side of the coin.
- Just like you said,
especially with the huge experimental projects like this,
it's a large team and it does,
the nature of the Nobel Prize is 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?
I've seen a few ideas that are kind of fascinating.
Is, are you interested in them?
Sort of looking, I'm not speaking about five years.
Perhaps you could speak to the next five years,
but also the next hundred years.
- Yeah, so let me talk to both the instrument
and the science, okay?
Since that's, they go hand in hand.
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.
They've done more work to kind of develop the ideas,
but they're different from ours and we have ideas.
So, 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.
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.
- Yeah, you're traveling back in time.
- 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-
- Oh, interesting, yeah.
- 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.
- 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?
- Yeah, yeah, that's, 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?
- 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.
And so the big, so I'll say two things.
One is, how did it all start?
How did it happen?
And I'll give you at least one example
that we don't understand, but we should understand.
We don't know why we're here.
- Yes, no, we do not.
- I don't mean it philosophically.
I mean it in terms of physics, okay?
Now, what do I mean by that?
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.
Antimatter then annihilates matter and makes energy.
So in the early universe, you made somehow,
somehow a lot of matter and antimatter,
but there was an asymmetry.
Somehow there was more matter and antimatter.
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 this all matter.
We don't have any idea.
We have an ideas, but we don't have any,
we don't have any way to understand that
at the present time with the physics that we know.
- 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?
- 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 'cause we don't see matter,
§11Transcript · 1:36:57–1:46:24
anti-protons anywhere, no matter what we look at,
that it's all made out of matter.
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.
- Yeah.
- Physics-wise, not, you know,
not in terms of how we evolved and all that kind of stuff.
So-
- So there might be inklings of,
of some of the physics that gravitational-
- 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.
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.
- Do you think there's more Nobel Prize level ideas
to be discovered in relation to-
- I'd be shocked if there-
- Gravitational waves.
- 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.
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.
- Do you have a preference?
I keep seeing this E. Lisa idea.
- Yeah.
- Do you have a preference for earthbound
or spacefaring mechanisms for-
- They're complementary.
It's a little bit like-
- A signal.
- It's completely analogous
to what's been done in astronomy.
So astronomy from the time of Galileo
was done with visible light.
- 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.
So it's completely complementary
and it starts to be looking at different frequencies
just like we do with astronomy.
- 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?
- It actually is a little different.
It's three satellites separated
by hundreds of thousands of kilometers.
And they send a laser beam from one to the other.
And if the triangle changes shape a little bit,
they detect that from a passage.
- Did you say hundreds of thousands of kilometers?
- Yeah.
- Sending lasers to each other.
(laughing)
Okay.
- It's just engineering.
- Is it possible though?
- Yes. - Is it doable?
- Yes.
- Okay.
That's just incredible 'cause 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.
So getting away from earth, maybe you get away from--
- 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.
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.
This'll be in the 2030s when it--
- 2030s? - Yeah.
- This is incredible.
This is incredible.
Let me ask about black holes.
So what we're talking about is observing
orbiting black holes.
I saw the terminology of binary black hole systems.
- Binary black holes.
- That's when they're dancing?
Okay.
- They're both going around each other
just like the earth around the sun.
- Okay, is that weird that there's black holes
going around each other?
- So the finding binary systems of stars
is similar to finding binary systems of--
- Of black holes.
- Well, they were once stars.
So we haven't said what a black hole is physically yet.
- Yeah, what's a black hole?
- 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
in the gravitational field is so strong
that nothing can get out, including light.
And there's light gets bent in the gravitation,
if the space-time is warped enough.
And so even light gets bent around and stays in it.
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, 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?
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, and 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.
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.
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.
It's too small. - Too small.
- And we don't know exactly what,
but it's usually thought that a star has to be
at least three times as big as our sun
to make a black hole, but that's the physical way there.
You can make black holes.
That's the first explanation
that one would give for what we see,
but it's not necessarily true.
We're not sure yet.
- What we see in terms of, for the origins of black holes?
- No, the black holes that we see in gravitational waves.
- But you're also looking for the ones
who are binary solar systems.
- So they're binary systems,
but they could have been made from binary stars,
so there's binary stars around, so that's--
- Gotcha, so the first explanation
is that that's what they are.
- Gotcha.
- Other explanation, but what we see has some puzzles.
This is kind of the way science works, I guess.
We see heavier ones than up to,
we've seen one system that was 140 times
§12Transcript · 1:46:28–1:55:33
the mass of our own sun.
That's not believed to be possible
with the parent being a big star
because big stars can only be so big,
or they are unstable.
It's just the fact that they live in an environment
that makes them unstable.
So the fact that we see bigger ones,
they maybe come from something else.
It's possible that they were made in a different way
by little ones eating each other up,
or maybe they were made,
or maybe they came with the Big Bang,
what we call primordial,
which means they're really different,
they came from that.
We don't know at this point.
If they came with the Big Bang,
then maybe they account for what we call dark matter
or some of it.
- Hmm, like there was a lot of them,
if they came with, 'cause there's a lot of dark matter.
- Yeah.
- But will gravitational waves give you
any kind of intuition about the origin of these oscillating?
- We think that if we see the distributions,
enough of them,
the distributions of their masses,
the distributions of how they're spinning.
So we can actually measure
when they're going around each other,
whether they're spinning like this or--
- The direction of the spin?
Or no, the orientation.
- Whether the whole system has any wobbles.
- What?
So this is now, okay.
We're doing that.
- And then you're constantly kind of crawling back
and back in time.
- And we're crawling back in time
and seeing how many there are as we go back.
And so do they point back to--
- So you're like, what is that discipline called?
Cartography or something?
You're like mapping the early universe
via the lens of gravitational waves.
- Not yet the early universe,
but at least back in time.
- Earlier, right.
So black holes are this mathematical phenomenon,
but they come about in different ways.
We have a huge black hole
at the center of our galaxy and other galaxies.
Those probably were made some other way.
We don't know when the galaxies themselves
had to do with the formation of the galaxies.
We don't really know.
So the fact that we use the word black hole,
the origin of black holes might be quite different
depending on how they happen.
They just have to in the end have a gravitational field
that will bend everything in.
- How do you feel about black holes as a human being?
There's this thing that's nearly infinitely dense,
doesn't let light escape.
Isn't that kind of terrifying?
Feels like the stuff of nightmares.
- I think it's an opportunity.
- To do what exactly?
(laughing)
- So like the early universe is an opportunity.
If we can study the early universe,
we can learn things like I told you.
And here again, we have an embarrassing situation in physics.
We have two wonderful theories of physics,
one based on quantum mechanics, quantum field theory.
And we can go to a big accelerator like at CERN
and smash particles together
and almost explain anything that happens beautifully
using quantum field theory and quantum mechanics.
Then we have another theory of physics
called general relativity,
which is what we've been talking about most of the time,
which is fantastic at describing things at high velocities,
long distances, and so forth.
So that's not the way it's supposed to be.
We're trying to create a theory of physics,
not two theories of physics.
So we have an embarrassment
that we have two different theories of physics.
People have tried to make a unified theory,
what they call a unified theory.
You've heard those words for decades.
They still haven't.
That's been primarily done theoretically
or people actively do that.
My personal belief is that like much of physics,
we need some clues.
So we need some experimental evidence.
So where is there a place?
If we go to CERN and do those experiments,
gravitational waves or general relativity don't matter.
If we go to study our black holes,
elementary particle physics doesn't matter.
We're studying these huge objects.
So where might we have a place
where both phenomenon have to be satisfied?
An example is black holes.
- Inside black holes.
- Yeah.
So we can't do that today.
But when I think of black hole,
it's a potential treasure chest
of understanding the fundamental problems of physics
and maybe can give us clues
to how we bring the embarrassment
of having two theories of physics together.
That's my own romantic idea.
- What's the worst that could happen?
It's so enticing.
Just go in and look.
Do you think, how far are we away from figuring out
the unified theory of physics,
a theory of everything?
What's your sense?
Who will solve it?
Like what discipline will solve it?
- Yeah.
I think so little progress has been made
without more experimental clues, as I said,
that we're just not able to say that we're close
without some clues.
The most popular theory these days
that might lead to that is called string theory.
- Yeah.
- And the problem with string theory is it works,
it solves a lot of beautiful mathematical problems
we have in physics.
And it's very satisfying theoretically,
but it has almost no predictive,
maybe no predictive ability
because it is a theory that works in 11 dimensions.
We live in a physical world of three space
and one time dimension.
In order to make predictions in our world
with string theory,
you have to somehow get rid of these other seven dimensions.
That's done mathematically
by saying they curl up on each other
on scales that are too small to affect anything here.
But how you do that, and that's okay,
that's an okay argument,
but how you do that is not unique.
So that means if I start with that theory
and I go to our world here,
I can't uniquely go to it.
- Which means it's not predictive.
- It's not predictive.
- And that's actually--
- And that's a killer, that's a killer.
- And string theory is,
it seems like from my outsider's perspective
has lost favor over the years,
perhaps because of this very idea.
- Yeah, it's a lack of predictive power.
I mean, science has to connect to something
where you make predictions as beautiful as it might be.
So I don't think we're close.
I think we need some experimental clues.
It may be that information
on something we don't understand presently at all,
like dark energy, or probably not dark matter,
but dark energy or something might give us some ideas.
But I don't think we're,
I can't envision right now in the short term,
meaning the horizon that we can see
how we're gonna bring these two theories together.
- A kind of two-part question,
maybe just asking the same thing in two different ways.
One question is,
do you have hope that humans will colonize the galaxy,
so expand out, become a multi-planetary species?
Another way of asking that,
from a gravitational and a propulsion perspective,
do you think we'll come up with ways
to travel closer to the speed of light,
or maybe faster than the speed of light,
which would make it a whole heck of a lot easier
to expand out into the universe?
- Yeah.
Well, I think,
that's very futuristic.
I think we're not that far from being able
to make a one-way trip to Mars.
That's then a question of,
whether people are willing to send somebody
on a one-way trip.
- Oh, I think they are.
There's a lot of, the Explorer's burned bright
§13Transcript · 1:55:36–2:05:11
and with their hearts.
- Yeah, yeah, exactly.
- There's a lot of people willing to die
for the opportunity to explore new territory.
- Yeah, so, you know,
this recent landing on Mars is pretty impressive.
They have a little helicopter that can fly around.
You can imagine,
you can imagine in the not too distant future
that you could have,
I don't think civilizations colonizing,
I can envision,
but I can envision something more like the South Pole.
We haven't colonized Antarctica,
'cause it's all ice and cold and so forth,
but we have stations.
So we have a station that's self-sustaining
at the South Pole.
I've been there.
It has--
- Wow, really?
- Yeah.
- What's that like?
'Cause there's parallels there to go to Mars.
- It's fantastic.
- What's the journey like?
- The journey involves going,
the South Pole station is run in the US
by the National Science Foundation.
I went because I was on the National Science Board
that runs the National Science Foundation.
And so you get a VIP trip if you're healthy enough
to the South Pole to see it,
which I took.
You fly from the US to Australia,
to Christ Church in Australia, Southern Australia.
And from there you fly to McMurdo Station,
which is on the coast.
And it's the station with about a thousand people
right on the coast of Antarctica.
It's about a seven or eight hour flight,
and they can't predict the weather.
So when I flew from Christ Church to McMurdo Station,
they tell you in advance,
you do it in a military aircraft,
they tell you in advance
that they can't predict whether they can land
'cause they have to land on--
- That's reassuring.
- Yeah, and so about halfway the pilot got on and said,
"Sorry, this is a," they call it a boomerang flight.
You know, a boomerang goes out and comes back.
So we had to stay a little while in Christ Church,
but then we eventually went to McMurdo Station
and then flew to the South Pole.
The South Pole itself is,
when I was there, it was minus 51 degrees.
That was summer.
It has zero humidity.
And it's about,
11,000 feet altitude
because it's never warm enough for anything to melt.
So it doesn't snow very much,
but it's about 11,000 feet of snowpack.
So you land in a place that's high altitude,
cold as could be,
and incredibly dry,
which means you have a physical adjustment.
The place itself is fantastic.
They have this great station there.
They do astronomy at the South Pole.
- Nature-wise, is it beautiful?
What's the experience like?
Or is it like visiting any town?
- No, it's very small.
There's only less than 100 people there
even when I was there.
There were about 50 or 60 there,
and in the winter there's less, half of that.
Their winter.
- It gets real cold.
- It gets really cold, yeah.
But it's a station.
I mean, we haven't gone beyond that.
On the coast of Antarctica,
they have greenhouses and they're self-sustaining
in McMurdo Station,
but we haven't really settled more
than that kind of thing in Antarctica,
which is a big country,
or a big plot, a big piece of land.
So I can't envision kind of colonizing
at people living so much,
as much as I can see the equivalent
of the South Pole Station.
- Well, in the computing world,
there's an idea of backing up your data,
and then you wanna do off-site backup
to make sure that if your whole house burns down,
that you can have a backup off-site of the data.
I think the difference between Antarctica and Mars
is Mars is an off-site backup.
That if we have nuclear war,
whatever the heck might happen here on Earth,
it'd be nice to have a backup elsewhere.
And it'd be nice to have a large enough colony
where we sent a variety of people,
except a few silly astronauts in suits,
have an actual vibrant,
get a few musicians and artists up there,
get a few, maybe one or two computer scientists.
Those are essential.
Maybe even a physicist, but I'm not sure.
- Yeah, maybe not.
So that comes back to something you talked about earlier,
which is the Fermi's paradox,
because you talked about having to escape.
And so the missing, one number you don't know how to use
in Fermi's calculation, or Drake, who's done it better,
is how long do civilizations last?
- Yeah.
- We've barely gotten to where we can communicate
with electricity and magnetism,
and maybe we'll wipe ourselves out pretty soon.
- Are you hopeful in general?
Like you think we've got another couple hundred years
at least?
Are you worried?
- Well, no, I'm hopeful,
but I don't know if I'm hopeful in the long term.
If you say,
are we able to go for another couple thousand years?
I'm not sure.
I think we have where we started,
the fact that we can do things
that don't allow us to kind of keep going,
or there can be, whether it ends up being a virus
that we create, or it ends up being the equivalent
of nuclear war, or something else.
It's not clear that we can control things well enough.
- So speaking of really cold conditions,
and not being hopeful, and eventual suffering,
and destruction of the human species,
let me ask you about Russian literature.
You mentioned, how's that for a transition?
I'm doing my best here.
You mentioned that you used to love literature
when you were younger, and you were even,
or hoping to be a writer yourself,
that was the motivation.
And some of the books I've seen that you listed
that were inspiring to you was from Russian literature,
like I think Tolstoy, Dostoevsky, Solzhenitsyn.
- Yeah, right.
- Maybe in general you can speak to your fascination
with Russian literature, or in general,
what you picked up from those.
- Not surprised you picked up on the Russian literature.
- I'm sorry. - With your background,
but that's okay.
(both laughing)
When I--
- You should be surprised I didn't make
the entire conversation about this.
That's the real surprise.
- I didn't really become a physicist,
or want to go in science, until I started college.
So when I was younger, I was good at math,
and that kind of stuff, but I didn't really,
I came from a family, nobody went to college,
and I didn't have any mentors.
But I liked to read when I was really young.
And so when I was very young, I read,
I always carried around a pocketbook and read it.
And my mother read these mystery stories,
and I got bored by those eventually.
And then I discovered real literature,
I don't know at what age, but about 12 or 13.
And so then I started reading good literature,
there's nothing better than Russian literature, of course.
- Thank you.
I heard you. - Reading good literature.
So I read quite a bit of Russian literature at that time.
And so you asked me about, well, I don't know,
I'll say a few words, Dostoevsky.
So what about Dostoevsky?
For me, Dostoevsky was important in,
I mean, I've read a lot of literature
'cause it's kind of the other thing I do with my life.
And he made two incredible,
and in addition to his own literature,
he influenced literature tremendously by having,
I don't know how to pronounce, polyphony.
So he's the first real serious author
that had multiple narrators.
And he absolutely is the first.
And he also was the first,
he began existential literature.
So the most important book that I've read in the last year
when I've been forced to be isolated
§14Transcript · 2:05:14–2:14:44
was existential literature.
I decided to reread "Camus, The Plague."
- Oh yeah, that's a great book.
- It's a great book, and it's right now to read it.
It's fantastic. - I think that book
is about love, actually.
Love for humanity, for all men.
- It has all the, if you haven't read it in recent years,
I had read it before, of course,
but to read it during this, 'cause it's about a plague,
so it's really fantastic to read now.
But that reminds me of, he was a great existentialist,
but the beginning of existential literature was Dostoevsky.
- Dostoevsky, yeah.
- So in addition to his own great novels,
he had a tremendous impact on literature.
- And there's also, for Dostoevsky,
unlike most other existentialists,
he was, at least in part, religious.
I mean, religiosity permeated his idea.
I mean, one of my favorite books of his is "The Idiot,"
which is a Christ-like figure in there.
- Well, there's Prince Mishkin, is that his name?
- Prince Mishkin, yeah.
- Yeah, Mishkin.
- Yeah, Mishkin.
- Yeah.
- That's one thing about,
so you read it in English, I presume?
- Yeah, yeah.
- Yeah, so that's the names,
that's what gets a lot of people,
is there's so many names, so hard to pronounce,
you have to remember all of them.
It's like, you have the same problem.
- But he was a great character, so that, yeah.
- I kind of, I have a connection with him,
'cause I often, the title of the book, "The Idiot,"
is, I kind of, I often call myself an idiot,
'cause that's how I feel, I feel so naive about this world,
and I'm not sure why that is,
maybe it's genetic or so on,
but I have a connection,
a spiritual connection to that character.
- To Mishkin.
- To Mishkin, yeah, that you're just--
- But he was far from an idiot.
- No, in some sense, in some sense.
But in another sense, maybe not of this world.
- In another sense, he was, yeah.
I mean, he was a bumbler, a bunker.
- But you also mentioned Solzhenitsyn,
very interesting, did--
- And he always confused me, of course,
he was really, really important
in writing about Stalin,
and first getting in trouble,
and then later he wrote about Stalin in a way,
I forget what the book was,
in a way that was very critical of Lenin.
- Yeah, he's evolved through the years,
and he actually showed support for Putin eventually.
It was a very interesting transition he took,
no, journey he took through thinking about Russia
and the Soviet Union,
but I think what I get from him is basic,
it's like Viktor Frankl has this "Man's Search for Meaning,"
I have a similar kind of sense
of the cruelty of human nature,
cruelty of indifference,
but also the ability to find happiness
in the small joys of life,
that's something, there's nothing like a prison camp
that makes you realize you could still be happy
with a very, very little.
- Well, yeah, his description of how to make,
how to go through a day and actually enjoy it
in a prison camp is pretty amazing.
- Yeah.
- Oh, and some prison camp,
I mean, it's the worst of the worst.
- The worst of the worst.
And also just, you do think about
the role of authoritarian states,
in hopeful, idealistic systems
somehow leading to the suffering of millions.
And I, you know, this might be arguable,
but I think a lot of people believe that Stalin,
I think genuinely believed that he's doing good
for the world, and he wasn't.
This is a very valuable lesson that
even evil people think they're doing good.
Otherwise it's too difficult to do the evil.
The best way to do evil is to believe,
frame it in a way like you're doing good.
And then this is a very clear picture of that,
which is the Gulags.
And Solzhenitsyn is one of the best people to reveal that.
- Yeah.
The most recent thing I read, it isn't actually fiction,
was the woman, I can't remember her name,
who got the Nobel Prize about within the last five years.
I don't know whether she's Ukrainian or Russian,
but their interviews, have you read that?
- Interview of Ukrainian survivors of--
- Well, I think she may be originally Ukrainian.
The book's written in Russian and translated into English,
and many of the interviews are in Moscow and places.
But she won the Nobel Prize
within the last five years or so.
But what's interesting is that
these are people of all different ages,
all different occupations and so forth,
and they're reflecting on their reaction
to basically the present Soviet system,
the system they live with before.
There's a lot of looking back by a lot of them with,
well, it being much better before.
- Yeah.
I don't know what,
in America, we think we know the right answer,
what it means to build a better world.
I'm not so sure.
I think we're all just trying to figure it out.
- Yeah, there's-- - We're doing our best.
- I think you're right.
- Is there advice you can give to young people today,
besides reading Russian literature at a young age,
about how to find their way in life,
how to find success in career or just life in general?
- Uh, I just,
my own belief, it may not be very deep,
but I believe it.
I think you should follow your dreams,
and you should have dreams,
and follow your dreams if you can,
to the extent that you can.
And we spend a lot of our time
doing something with ourselves,
in my case, physics, in your case, I don't know,
whatever it is, machine learning and this.
(chuckles)
We should, yeah, I should have fun.
- What was, wait, wait, wait, wait,
follow your dreams, what dream did you have?
'Cause there's-- - Well, originally I was--
- 'Cause you didn't follow your dream.
I thought you were supposed to be a writer.
- Well, I changed along the way.
I was gonna be, but I changed.
- What happened? - That was what happened?
Oh, I read, I decided to take
the most serious literature course in my high school,
which was a mistake.
I'd probably be a second-rate writer now.
- Could be a Nobel Prize-winning writer.
- And the book that we read,
even though I had read Russian novels,
I was 15, I think, cured me from being a novelist.
- Destroyed your dream? - Yes.
- Cured you, okay, what was the book?
- "Moby Dick." - Okay.
- So why "Moby Dick?" - Yeah, why?
- And so I've read it since, and it's a great novel.
Maybe it's as good as the Russian novels.
- I've never made it through.
I, well, it was too boring, it was too long.
- Okay, your words are gonna mesh with what I say.
- Excellent. - And you may have
the same problem at a older age.
- Maybe that's why I'm not a writer. (laughs)
- It may be, so the problem is, "Moby Dick" is,
what I remember was there was a chapter
that was maybe 100 pages long,
all describing this, why there was Ahab and the white whale,
and it was the battle between Ahab
with his wooden peg leg and the white whale.
And there was a chapter that was 100 pages long,
in my memory, I don't know how long it really was,
that described in detail the great white whale
and what he was doing and what his fins were like
and this and that, and it was so incredibly boring,
the word you used, that I thought,
if this is great literature, screw it.
- Oh, fascinating. - Okay?
Now, why did I have a problem?
I know now in reflection, because I still read a lot,
and I read that novel, you know,
after I was 30 or 40 years old,
and the problem was simple, I diagnosed what the problem was.
I, that novel, in contrast to the Russian novels,
which are very realistic and, you know, point of view,
is one huge metaphor.
- Oh, yeah.
- At 15 years old, I probably didn't know the word,
and I certainly didn't know the meaning of a metaphor.
- Yeah, like, why do I care about a fish?
Why are you telling me all about this fish?
- Exactly, it's one big metaphor,
so reading it later as a metaphor, I could really enjoy it.
§15Transcript · 2:14:48–2:22:49
But the teacher gave me the wrong book,
or maybe it was the right book,
'cause I went into physics, and so,
but it was truly, I think, I may oversimplify,
but it was really that I was too young to read that book,
because, not too young to read the Russian novels,
interestingly, but too young to read that,
because I probably didn't even know the word,
and I certainly didn't understand it as a metaphor.
- Well, in terms of fish,
I recommend people read "Old Man and the Sea,"
much shorter, much better, still a metaphor, though, so,
but you can read it just as a story
about a guy catching a fish, and it's still fun to read.
I had the same experience as you, not with Moby Dick,
but later in college, I took a course on James Joyce.
Don't ask me why.
I was majoring in computer science,
I took a course on James Joyce,
and I was kept being told that he is widely considered,
by many considered, to be the greatest literary writer
of the 20th century.
And I kept reading, I think, so his short story is,
"The Dead," I think it's called, it was very good.
Well, not very good, but pretty good.
And then, "Ulysses." - It's actually very good.
- It is very good.
I mean, "The Dead," the final story,
still rings with me today.
But then, "Ulysses" was, I got through "Ulysses"
with the help of some Cliff Notes and so on, but,
and so I did "Ulysses" and then "Finnegan's Wake."
The moment I started "Finnegan's Wake,"
I said, "This is stupid.
That's when I went full into, I don't know,
that's when I went full Kafka, Bukowski,
like people who just talk about the darkness
of the human condition in the fewest words possible,
and without any of the music of language.
So it was a turning point as well.
I wonder when is the right time
to appreciate the beauty of language.
Like even Shakespeare, I was very much off-put
by Shakespeare in high school,
and only later started to appreciate its value
in the same way.
Let me ask you a ridiculous question.
- Okay.
- I mean, because you've read Rush Literature,
let me ask this one last question.
I might be lying, there might be a couple more,
but what do you think is the meaning of this whole thing?
You got a Nobel Prize for looking out
into the, trying to reach back
into the beginning of the universe,
listening to the gravitational waves,
but that still doesn't answer the why.
Why are we here?
Beyond just the matter and antimatter.
The philosophical question.
- The philosophical question about the meaning of life
I'm probably not really good at.
I think that
the
the individual meaning,
I would say rather simplistically,
is whether you've made a difference,
a positive difference, I'd say,
for anything besides yourself.
Meaning you could have been important to other people,
or you could have discovered gravitational waves
that matters to other people or something,
but something beyond just existing on the Earth
as an individual.
So your life has meaning if you have affected
either knowledge or people or something beyond yourself.
- Do you-- - That's a simplistic
statement, but it's about as good as I can have.
- That may, in all of its simplicity, it may be very true.
Do you think about,
does it make you sad that this ride ends?
Do you think about your mortality?
- Yeah.
- Are you afraid of it?
- I'm not exactly afraid of it, but saddened by it.
And
you know, I'm old enough to know that
I've lived most of my life,
and
I enjoy being alive.
I can imagine being sick and not wanting to be alive,
but I'm not.
And so
I'm--
- It's been a good ride.
- Yeah, and I'm not happy to see it come to an end.
I'd like to see it prolong.
But
I don't,
I don't fear the dying itself,
or that kind of thing.
It's more I'd like to prolong
what is, I think, a good life
that I'm living and still living.
- That's kind of,
it's sad to think that the fineness of it
is the thing that makes it special.
And also sad to,
to me at least, it's kind of,
I don't think I'm using too strong of a word,
but it's kind of terrifying, the uncertainty of it.
The mystery of it, you know.
- The mystery of death.
- The mystery of it, yeah, of death.
When we're talking about the mystery of black holes,
that's somehow distant, that's somehow out there.
And the mystery of our own--
- But even life, the mystery of consciousness,
I find so hard to deal with too.
I mean, it's not as painful.
I mean, we're conscious, but the whole magic of life,
we can understand, but consciousness,
where we can actually think and so forth, it's pretty--
- It seems like such a beautiful gift
that it really sucks that we get to let go of it,
we have to let go of it.
What do you hope your legacy is?
As I'm sure they will.
Aliens, when they visit,
and humans have destroyed all of human civilization.
Aliens read about you in an encyclopedia
that we'll leave behind.
What do you hope it says?
- Well, I would hope they,
to the extent that they evaluated me,
felt that I helped move science forward
as a tangible contribution,
and that I served as a good role model
for how humans should live their lives.
- And were part of creating
one of the most incredible things humans have ever created.
- So yes, there's the science,
that's the Fermi thing, right?
- And the instrument, I guess.
- And the instrument.
The instrument is a magical creation,
not just by a human, by a collection of humans.
The collaboration is,
that's humanity at its best.
I do hope we last quite a bit longer,
but if we don't, this is a good thing to remember humans by.
At least they built that thing.
That's pretty impressive.
Barry, this was an amazing conversation.
Thank you so much for wasting your time
in explaining so many things so well.
I appreciate your time today.
- Thank you.
- Thanks for listening to this conversation
with Barry Barish.
To support this podcast,
please check out our sponsors in the description.
And now, let me leave you with some words
from Werner Heisenberg, a theoretical physicist
and one of the key pioneers of quantum mechanics.
"Not only is the universe stranger than we think,
"it is stranger than we can think."
Thank you for listening and hope to see you next time.
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