Josh Chamot: It has been a big year.
I mean you guys are talking about the Nobel Prize,
you are talking about multi messenger.
You are talking about major lifetime accomplishments
for yourselves and for the scope
and now we are looking at the future.
So what comes next for LIGO? What do you see happening next?
Rainer Weiss: Well, I will give you the near term-
Josh Chamot: Yeah.
Rainer Weiss: In the near term,
we have to get to design sensitivity
for the apparatus that's in, that's now has been installed.
That isn't the best thing we can make,
it is just that apparatus that is in there now
is not working at exactly where we expect it to.
Josh Chamot: So the potential for the instrument
that is already there-
Rainer Weiss: There is another,
somewhere around the factor of two,
let's say maybe, which is big as you know
when you start talking about distance
and you talk about the rate of events.
That is a factor of 10 almost in events.
That is a big factor-
I mean now we are seeing an event every month,
maybe every couple of months.
So you know, eight weeks you have an event a week,
maybe a little less than that.
Now, that doesn't get us all what we want.
I mean we can have more events
but there are parts of the events for example,
just let's say the black hole events by themselves.
We'd love to see for example what happens
at the very end of that collision.
Right now, the data if you look carefully at the data,
for a single event you can't tell very much
about a wonderful new thing that happens
when the black holes finally merge,
and they make a new black hole. The geometry around that,
the geometry itself has normal modes of its own.
It sings, it rings like a bell, we never see that.
That's been calculated for years,
and you would love to see those normal modes exist.
Do they have the right frequencies?
The other thing we love to know more about this system
is for example is we would love to know more about the spins.
The individual spins.
Just take the thing we already know
and even for those it would be nice to have some improvements
even above where we are now
or where we will be when we make that factor of two improvement,
and people are thinking of sort of closer term improvements,
that each will have a scientific goal of sorts.
For example; if we get another factor of two above
that you might get a chance to see the ring down, okay.
Josh Chamot: The ring down
after the collision of the two black holes-
Rainer Weiss: The collision, yeah, I mean depends on,
close one you could see very easily.
Josh Chamot: Yeah, now that is-
Kip S. Thorne: But, if you could see several normal modes
of vibration you can really test,
is this black hole really the type that was described
by the mathematics of general relativity
or the so called Kerr black hole.
If the frequencies and the ring down rates are not quite right
then something is fundamentally different.
Josh Chamot: So you have been calculating
and you have been exploring all the ideas of what could be-
Kip S. Thorne: Well, my colleagues have been-
Josh Chamot: Or your colleagues have been
and you have been helping with the theory.
But what have you been hoping to see,
so when we get to this next level of instrumentation-
Rainer Weiss: Be careful that you get the thing right.
I'm talking about small increments.
Josh Chamot: Okay.
Rainer Weiss: There are other things to talk about.
Josh Chamot: Right. Right, yeah.
Kip S. Thorne: Yeah, I mean [crosstalk].
Rainer Weiss: And these are things near term,
let's say within the next five years.
Josh Chamot: So, say within the next thirty years ...
Rainer Weiss: That's something else.
That's a very different story. [crosstalk]
Kip S. Thorne: Within the next 30 years,
with a new instrument, starting over again.
A huge, huge improvement.
Going, seeing out say ten or thirty times farther than LIGO,
than the current instruments of design sensitivity.
Maybe a hundred times
farther than the current instruments today.
Josh Chamot: So you're getting a whole bunch of-
Kip S. Thorne: And a hundred times farther means
the volume of the universe a million times bigger.
Josh Chamot: That's huge.
Kip S. Thorne: A million times bigger.
That means seeing black hole mergers,
every one that occurs in the universe
out to what we call a Red Shift of 15,
and we think almost all of them are younger than that.
That there were perhaps none, or hardly any,
ever formed earlier than that. Seeing basically everything.
Josh Chamot: So when you get that scope at that scale of
seeing all of these collisions in all of this space,
what sorts of events might you expect to find
that we just can't see now?
Things that are at that earlier stage.
Kip S. Thorne: They'll have extremely strong signals
that will enable you to test the dynamics
of curved space-time when it's oscillating wildly.
The shape of space is oscillating wildly.
The rate of flow of time is oscillating wildly.
Sort of the most extreme thing short of quantum gravity,
the most extreme thing that can occur in terms of space
and time in the universe.
To study it with exquisite precision.
Josh Chamot: So-
Kip S. Thorne: To me that's the most exciting thing.
But beyond that,
to do a census of all the black holes in the universe,
or the colliding black holes in the universe,
below about a few hundred solar masses.
And, yeah, I mean, it's,
and do a census with very high precision.
And then thereby to work out, observationally,
the history of black hole formation and evolution
in the universe. When did they first form?
Were there black holes that formed in the very,
very first population of stars?
Do some of them precede the first population of stars?
Do most of them form through hierarchical mergers
inside globular clusters. You form little black holes,
they collide, make bigger black holes,
they collide, make bigger black holes.
And what is the history? How does this happen?
Josh Chamot: So at that scale
you're talking about fundamental processes
that we can't explore in other ways yet.
Okay, that's great.
And then Barry, how are we going to make this happen?
Kip S. Thorne: First we gotta know
how to make it happen, technically.
Josh Chamot: Right.
Barry C. Barish: I think that's the real challenge now.
And that's hard work, it takes a long time
to develop the technologies and you have to start early.
Josh Chamot: And this is fundamental engineering,
in the sense that we don't even know how to do it yet.
Barry C. Barish: Yeah, well first we have to pick
what are the priorities. You can make all the plans,
but they make take very different kinds of instruments,
or optimization of the instruments.
So what we have to do is understand
what kind of instruments conceptually we can make.
We're just starting to do that,
they've done more in Europe than we have.
And then we have to ask what it means in terms
of developing the technologies and cost, things like that.
So the technologies that we talk about for example,
are cooling the whole thing to reduce the thermal effects,
and that's hard. The materials you use change
when you cool it introduces shaking
and so it's a difficult problem.
Josh Chamot: So when you change one part of the system,
you've then gotta accommodate, and you're the engineer too,
so you change one part of the system,
you've got to accommodate for the changes
that are going to happen elsewhere.
Rainer Weiss: Well there are a lot of different things,
I mean there's a whole set of things that we already now know.
We would like to be able to do.
Let's put it this way, on paper we can see what Kip was saying.
If cooling using quantum tailored light,
using new kinds of test masses, new kinds of coatings,
a whole bunch of steps have to be taken.
Kip S. Thorne: Conceptually
Rainer Weiss: But it's all conceptual at this moment.
But if you can achieve, there's no fundamental reason
we shouldn't be able to do this.
Kip S. Thorne: Each of the conceptual ideas appear
to be doable in this time scale, but the difference between that
and really pulling it off is enormous.
Even I, as a theorist, know that.
Rainer Weiss: I mean that's the difference between why
when in the beginning of LIGO we could have already
anticipated a lot of stuff, we did in fact.
But then to make it actually happen and build the things,
and not get into trouble with something you forgot about,
or something which was more difficult
to build than you thought.
Or a noise that you hadn't ever even anticipated.
And that's sort of that kind of thing that happens.
And that's what takes the time,
but you have to have the ability to do that.
You have to have some funds to do that,
and you have to have places to do that, and to try it out.
So these are things which we can lay out now a program
of how you might get a factor of a hundred,
but now you have to go and say,
"Okay, let's start working on them, one after the other."
Josh Chamot: But then you've already gotten to
this milestone here, and what is that like to kind of
arrive at a point where you know,
there were all the sleepless nights, all the unknowns
and you had decades of that.
Rainer Weiss: The idea for all of this,
sort of, started to level when our technology was good
to strains of 10^-14, maybe. Maybe.
So now we're at strains of 10^-21.
Kip S. Thorne: And we knew that's where we had to go.
Rainer Weiss: And we knew we had to go there.
Because Kip told us we had to be there
Kip S. Thorne: No, my, the community I come from
were targeting 10^-21 as early as 1978.
Josh Chamot: Wow, okay,
so you knew and that was unimaginable at the time.
Rainer Weiss: Well of course, yeah.
But we could see how to do it maybe.
And, now the point is it gets harder and harder.
The thing that we're talking about now,
we're already at a point where you know;
if you now want another factor of ten for example,
or even let's say 100.
You can see, ten is, let's start there.
You already have steps which are in some regards
are a little more difficult than the ones you took earlier.
For example, one of the things that are being testing now
is we're trying to use Quantum Tailored Light.
That's been done by people in Europe.
Josh Chamot: And what is Quantum Tailored Light?
Rainer Weiss: It's called Squeeze Light.
It's light that does not have the same probability
distribution for making noise than the ordinary light
we've been using out of lasers. It's tailoring lights.
So it has less noise in certain frequency bands.
That's an elegant technique
and we're pushing that very hard,
but that's going to get us, we have to learn
how to use more intensity. How to, that's another thing.
We have to learn how to make the coatings
so that they themselves are not making thermal noise
as much as it is now.
Cooling everything is one way to go.
It may not be the only way to do it.
You may in fact want to use crystalline coatings
if you want a specific,
so, there's all these branch points and people [crosstalk]
Kip S. Thorne: Looking back to the part where we came from,
the key step was turning this thing into a real project
with a real leader which is Barry,
who could develop a program to pull this off
step-by-step-by-step-by -step-by-step.
That's a big part.
It's the R&D but it's also developing
a very wisely defined program
that Barry is the world expert at.
Josh Chamot: You know, that's an interesting point in that -
that's not the sexy point.
You know, you're getting everybody organized -
Rainer Weiss: Well be careful.
Yeah, it gets pretty damn interesting.
Josh Chamot: That's what I'm getting at is that,
And yet that's so critical for projects large and small
is you can envision whatever you want,
but if you can't execute it
then it's just still on the drawing board.
So, dive into that a little bit.
I mean, how do you get from wrangling thousands of people;
at least hundreds of people and all of this crazy engineering
and concept into something that actually happened.
Barry C. Barish: Well, I think if you have a clear goal
it's easier.
Right now what we are talking about is harder,
which is that we want to develop the techniques
that can move us to the next step
and you're not sure which ones will pan out.
There's not an easy kind of programmatic way
to make them hierarchical before you do it.
Like you do when you do something in your life,
you pick priorities.
It's hard to do that at this stage.
We know the different areas that can get us
this factor of 100
and you have to make some choices
and try to pursue them.
That's why it's hard, important to start as early as possible
so that when we start doing the project
which becomes very difficult, we have all the tools
and we have the concepts and we know.
So we have the ideas now, or the concepts,
but we don't know which ones are problematic,
which ones can be realized. They interact with each other.
If you cool it, because that's quieter,
then you have to use different materials.
We don't which materials and so forth.
Josh Chamot: Right. And then you have to be flexible
when things don't go the way you expect.
Rainer Weiss: Well you have parallel developments.
I mean, you try and do that.
Josh Chamot: Yeah. Rainer Weiss: If you can. Yeah.
Barry C. Barish: So, in a sense,
we know more about what we can gain scientifically.
What we need is an aggressive program
to develop the techniques.
Josh Chamot: Right.
Barry C. Barish: We've done the easy stuff.
Josh Chamot: Right. Well, what do you think ...
Rainer Weiss: Easy.
Josh Chamot: At this point, you've also reached
a certain point in terms of the science.
In terms of matching the theory to the observations,
and then getting to a level of understanding
of what's happening and getting excited about what's being seen.
Can you, this may be something you may not want to answer,
but is there a way to, if you could really arm wave,
anticipate some of the things that you may not expect?
Barry C. Barish: It's a good question,
because we try to look for the unexpected.
We have a whole group that looks at that.
We have algorithms, but that's almost impossible
to do that without some biases.
So, we use a certain mathematical technique
called wavelets to develop a way
that doesn't have a physical origin to look for it.
In fact, it was that method that saw the first event
rather than the method where we were looking exactly
for what we found. But, that's got biases in it.
So how to look at our data for the unexpected
is a big challenge.
I actually think some new techniques might be helpful.
For example, deep learning.
Where, in a sense, we can look at the data and look for things
that don't look like the patterns
we see with lots and lots of data normally.
Josh Chamot: Is it a big data problem
that we're all happy about here, because that's [crosstalk].
Barry C. Barish: Well, the question is,
when you look for something
and you don't know what you're looking for,
because that's exactly how we want to do it.
You have to have ways to do it that don't have the biases built
in that almost have to built in for us to look at data.
Rainer Weiss: Let me give you, since Kip isn't speaking up,
I'm going to do it for him.
He's made this analogy over and over.
I'll do it for him and he'll probably say
I didn't do it right, but let me try.
That is, if you look at what we're doing with this field,
we're now looking at something really quite different
than other astronomies have done.
The source of gravitational waves are accelerating mass.
Okay?
What almost all of our knowledge of the universe is based on
is accelerating charge. That's electromagnetic.
Josh Chamot: Yeah, yeah.
Rainer Weiss: Okay? Josh Chamot: Yeah.
Rainer Weiss: So, I'll give you a good example in a minute.
One example that I know
where that is going to make a profound difference.
But, the fact is that if you just look at the story
of even the one where we understood more.
Maybe charges be accelerating.
Each time we looked with a different instrument
in terms of the different wavelength,
or a different set of conditions at the source
which then radiated at a different wavelength,
you learn new stuff.
I mean, for example you found out that the universe
wasn't this placid thing as you look up
and it's never doing anything interesting.
I mean it's a hell of a place,
I mean it's crazy stuff going on everywhere,
but you learned that from x-ray astronomy, from radio astronomy.
You didn't learn that so much from optical astronomy.
So the thing is that, and this is sort of the way
Kip sort of made us all feel, and he's right,
here we're looking at it with a completely new way
of what nature's shaking is doing.
The mass shaking, would you expect not to find things
that you haven't thought of before?
I mean you're clearly already in a state,
the state we're already in.
We have already seen things which we now see,
which we knew about, in a new way.
In other words, we knew about black holes,
we didn't know they were in pairs.
We expected them to be in pairs, but nobody could tell you
how many pairs there were per unit volume.
That's one of the things we didn't know.
And the other thing is, we knew about neutron stars,
and now we've seen the crash and all that,
but we now can see things which we didn't see before,
but they are still in the context of things we knew about
but seeing them in a new way because of this new medium.
So now, is there a thing which is the other, the converse,
seeing things you don't know about
and because you have a new way to look.
I think it's gotta be something like that.
I can't prove it to you, but if it goes by analogy,
I fully expect it.
Now how to look for that is another problem.
Kip S. Thorne: Well now, my favorite place to look
is in the first one second of the life of the universe.
You can't see that electromagnetically,
because the universe is too hot and dense,
and electromagnetic waves, photons, wouldn't propagate.
Even neutrinos wouldn't propagate
in that first one second, gravitational waves
are the only thing that does. They're our ideal tool
and the physics that was going on in there,
we know pretty well back to when the universe
was a trillionth of a second, we don't know before that.
It gets more and more speculative
the farther back you get, so I just want to look and see.
And most likely, whatever this comes from then
is a stochastic background,
and so to be able to dig deep, after a stochastic background
that may come from the earliest moments of the universe,
is to me a huge goal for the future.
The third-generation instruments we talk about for the 2030's
would be able to do that at a rather amazing level,
a level that the amount of energy that we could detect,
the energy density in the universe
that you could detect is 10 to the minus 13,
a tenth of a trillionth of the amount
required to close the universe, is the way people measure it.
This is just a very impressive number.
There may or may not be something of that level,
but this will be the first attempt to really go after that,
up in our frequency band with gravitational waves.
Josh Chamot: It's pretty incredible
being at this milestone
to kind of think that we might be getting within decades
of seeing that far back into that early universe.
Rainer Weiss: Well, we were seeing
electromagnetically pretty far back.
Josh Chamot: Right. Rainer Weiss: Yeah.
300,000 years after the explosion,
that's just pretty damn close to the explosion.
Josh Chamot: It is.
Rainer Weiss: I mean, the expanse example which is
a little more pedestrian that I want to tell you.
Is in fact if, and this is going to happen.
It may not today but we're going to see
a Super Nova there's no doubt.
That is the sort of thing where nobody has ever seen inside one.
Gravitational waves allow you that because they don't scatter,
they just come right out.
Kip S. Thorne: And the theoretical simulations
cannot explain what's seen.
Rainer Weiss: Yeah.
Kip S. Thorne: We don't know what causes
the explosion to occur. There are ideas,
but different models give different predictions
and people have been struck, the theorists, the simulators,
have been struggling since the early 1960s.
And the combined observation of gravitational waves,
neutrinos and electromagnetic waves
will very likely solve that problem
when we see the first one or several supernovae.
Josh Chamot: It's incredible.
I think even from every level of the public's
understanding of science, I think it's the sort of thing
that people are really going to be moved by.
Thank you very much for joining me.
I know we're running out of time.
Rainer Weiss: That's good. Well thank you for having us.
Josh Chamot: Absolutely.