(MUSIC) (MUSIC) On September 14th, 2015.
These long arms of the LIGO Laser Interferometer Gravitational-wave
Observatory in Livingston, Louisiana, and its twin detector, 1,900 miles away
in Hanford, Washington, appeared to make the first detection of
a wave of what is known as warped space created by a massive collision
of two black holes unlike anything astronomers had ever
seen in the visible universe. It would be just as 100 years of Einstein’s
general theory of relativity predicted, And the first time we on Earth
experienced and measured a remnant of the violent warping of
space and time that is a gravitational wave. If true LIGO's discovery would open up
the 95% of the universe that's dark to our existing observatories and
space-based telescopes. Until now, we have only seen warped spacetime --
we as scientists have only seen warped spacetime when it is very calm. As though we had only seen
the surface of the ocean on a very calm day
when it's quite glassy. We had never seen the ocean broiled
in a storm with crashing waves. The colliding black holes that
produced these gravitational waves created a violent storm in the
fabric of space and time. We began filming a documentary about LIGO
one month earlier, in August 2015. And we were there, at the LIGO Livingston
Observatory outside of Baton Rouge. We arrive on Sunday, September 13th,
three days before the planned launch of Advanced LIGO, the five year, $200 million
upgrade to the two exquisitely complex detectors, which even before the upgrade
were the most sensitive instruments for measurement the world had
ever known. What do they hope to measure? Ray Weiss is the creator
of the LIGO detectors. He describes the footprint, so to speak,
of a gravitational wave. Everybody who has contemplated it,
especially if they're engineers and
have their feet on the ground, that's when they throw you
out of the room. And they say that's not possible.
Now, how do I, let's put it into
some sort of context that you understand better. It's not easy to make a context
where it's understandable. But let's take the distance between
us and the sun. And so we want to measure that
to a precision of putting one extra atom, one extra atom,
in the path between the light that goes from the earth to the sun.
That is a tiny, tiny amount. Or another way of thinking about it is
it's like measuring the distance from the earth to the nearest star to a
precision of the width of a human hair. It's ridiculous, right? How will LIGO know and measure the waves?
The space between its mirrors is warped, stretched and distorted by the wave
as it passes through. The magic to do that is that if you
measure the size of something, you're measuring some absolute size. Interferometry measures the
difference in two distances. So we have a pair of mirrors that
are four kilometers apart. The gravitational wave has changed
the way you measure space between those two objects.
It has distorted the space. We send laser light into the interferometer
and that light bounces back and forth in the arms. But if they change their length for any reason,
including the passage of a gravitational wave, then that leaks a little light through
onto these in-vacuum photodiodes. And that's where we can read out the
signals. So the interferometer is designed to be sensitive to the differential
changes of the arm lengths. Gravitational waves are really hard
to understand, because there's no -- what's the medium, you know, what's
the thing, that's not like water waves or sound waves that propagate through air.
It's literally space itself that's fluctuating. And it turns out that space is really stiff.
So you need a really big force to be able to get that space to jiggle
back and forth to ripple. The crew and I knew all of this. And the fact that because the mirrors
are set 2.5 miles or four kilometers apart in two long vacuum tube arms,
LIGO had to take into account the curvature of the earth when placing
the mirrors and pointing the laser beams. We knew this, but we weren't prepared
for what we found when we arrived that Sunday. LIGO Livingston had been
knocked offline by an earthquake in Mexico 2000 miles away. We understood immediately that we
had walked into a different realm of the physical world. But looking back, it was an almost
perfect introduction. It was topped off a year and a half later
when we were in the control room of the Hanford detector
the moment it was knocked offline by an earthquake in Africa on the
other side of the world. We didn't feel the earthquake.
It wasn't the shaking. It was the low frequency aftershocks
that traveled around the world and knocked the fragile complexity
of this instrument out of lock. Distant, extremely large-magnitude quakes,
magnitude eight and above, they can have us offline for several hours
while the earth rings down and those waves travel around and around,
loop around the earth. LIGO hopes to measure a wave of
1 billion year old warped space in the most precise measurement
ever made in history. If successful. Yet an earthquake
you couldn't feel, from thousands of miles away
could knock them offline. Let's not even talk about the logging trucks
that rumbled past Livingston every day, or wind across the high desert of
eastern Washington that pushed and tilted the buildings
enough to throw the laser beams off track. Or even what they called
"ice craving ravens." But the loss of lock at Livingston
that Sunday is good for us. We were able to go down
one of the vacuum tube arms to interview Gabriela Gonzalez,
the Argentinean physicist who is the spokesperson
for the LIGO scientific collaboration, elected by the 1000 physicists and engineers
around the world who make up the collaboration. Some of them, like Rai Weiss
and Kip Thorne, have been working
on it for half a century. It has been Gaby Gonzalez's
life's work for 25 years. We are very excited about starting this run,
because it's the first time we'll do it with Advanced LIGO detectors.
We'll see farther than ever before, three times farther than we did
with Initial LIGO. But we are making it short.
We're only taking data for three months compared to the years we did before,
because we don't think that we have enough sensitivity to see events,
even if we wait for a year or so until we get better. So we don't have
high expectations of having a discovery. But we could! We could be lucky.
I mean, these events happen rarely, so we could be lucky and see an event.
Or there are some theories that are very optimistic theories that say that we
should be seeing coalescences of black holes, and who knows, they might be right! So gravitational waves, we like to
think of them as audio signals, because the frequency of the signals
we're looking at with these detectors are in the human audio range.
And we call this signal that these binary systems make before merging a "chirp"
because it's something like Whoop! I'm not good at doing that,
but it's something that goes up in pitch and amplitude
until it coalesces. I think that the fact that one
can use instruments of this precision to look at the structure of
of spacetime, it's a challenge that will put science and technology
at the forefront of everybody’s mind. Every child, every person will reading about this
in the newspaper and saying, "What? You can really measure these things
with lasers and mirrors and you're talking about black holes
and spacetime. That's amazing!" And that
is the change of mind that I really want. It's that amazing vision
of science and scientists and technology that makes us understand
the universe better. Just before leaving for Louisiana,
we learned that the formal launch of Advanced LIGO, after more than
a decade of development and five years of installation in the two
detectors, is being pushed back. They aren't ready. All of the
systems still aren't in place. Twelve hours after we talked with
Gabby Gonzalez, at 4:45 a.m. in Livingston Parish
on the morning of September 14th, William Parker is in the operator's chair
in the Livingston Control Room. He is alone that night. Nutsinee Kijbunchoo, the operator at Hanford,
also is alone. No one else is on site. Unknown to them, at 4:50 a.m. Louisiana time,
the LIGO computers register a spike in data coming from both detectors. And an algorithm
developed over more than a decade for just this purpose sends out an email alert
to only a handful of the data analysts. The voice alert system that would
have notified William and Nutsinee isn't working yet. As I understand it, and I'll
preface that by saying that I was not involved in this
particular chain of emails, but as I understand it,
emails went out to three or four people: Marco Drago at the AEI
in Hannover, Germany, Reid Essick at MIT and Sergey Klimenko at the
University of Florida. And there may be one or two
others who I’m not aware of. Basically there was an email alert
sent out by the algorithm itself, basically automated saying,
“Look, something interesting!" Marco looks at it and goes,
"Wow, this is significant. This is a very loud trigger,”
as we call it. This was a representation
from the data. And actually we have the two
detectors in the two rows. So this is the data
of the two detectors. And here we can see in both
the what is the signal. It was about, I think 11:30 a.m.
when Marco came running in. I did know that just a few days before, we'd had
problems with the hardware injection system. So we put in signals to test the instrument.
So what we did for the first 30 minutes was just try to figure out whether
this was a hardware injection. There was a little bit into that when
when we decided to just call the sites. because you can talk
to the control rooms. And Livingston told us it was middle of the night.
Nothing was happening there. People had already gone home.
I still thought they might have been doing a blind injection, which means that
they do a test, but they don't tell anyone, just to make sure that we can detect it.
We did that in the last science run and it was six months
before they told us. We had to get to the point where
we wrote a paper on it. Sergey Klimenko, I think,
was the next person. Sergey looked at it and said, "This is
not only an interesting loud trigger, it has to be a binary
black hole merger. When I saw this email,
I kind of woke up instantly. It was kind of so beautiful
that it was hard to believe it's true. You know, LIGO is
a discovery instrument. It looks at this unexplored
side of the universe. And therefore it's absolutely necessary
to look for something surprising. And this is what I do.
I like to do. And I have to say that it's not very simple
to search for unknown. It's like trying to find a black cat
in a dark room. Okay? This is a big challenge. So we're adjusting all our plans, because we've
seen an event in the data earlier this morning. In many ways, it looks
too good to be true. We're trying to keep our excitement
level down that this is a real event. It was 5 a.m.
this morning our time. So it's all still very new.
Lots of people are looking at this. And we see this beautiful wave form
in both detectors. It's so nice looking,
but we're so skeptical. We, of course, worry that we're being
pranked or tested somehow. But it really, really looks nice.
So it would have to be malign, So we're checking off those boxes. So that leaves the quote everybody
likes to use is the Sherlock Holmes quote: "Once you've eliminated the impossible,
whatever remains, no matter how improbable, has got to be the truth."
And so we're eliminating the impossible. So then the question is, can someone,
or someone's, interfere with the data stream, either in the hardware at the detectors,
or in the software later, and put in a signal
that looks like this? There are only, I don't know, you could count,
I don't think I need my two hands to count the people who could do that.
I could not do that. And these are all people
we talk to all the time. So you just, we just trust.
I mean, we just trust the core team of people that have that
knowledge of the instrument. We have been working
on this for decades. You know, I mean, there's this
wonderful thing that goes around, you know, is there some evil genius
that has laid this into us? This sort of Pandora's Box of questioning.
What if someone was maliciously trying to manipulate the gravitational
wave signal? How might they do it? This evil genius gets to be more and more
complicated, and more and more skilled as you delve into this in a
deeper and deeper way. So it's not just one evil genius.
It's a multiple group of evil geniuses. One of the hypotheses was that someone
could have taken a little iPod or some kind of music device and put one
in Hanford and another one in Louisiana, and then had some software which timed
an interaction to go out into electronics. In fact, two young LIGO scientists
had just been at both detectors, at Hanford last week, and they
had been working here late last night. They were here all weekend? Before every science run we do a set
of ambient noise coupling checks. Takes about a week to run all over the detector
and blast everything we can think of: magnetically, acoustically, vibrationally,
because we optimize for what hurts us the most. Is it possible that they left
something at both sites, because they were there last week, right? We have shakers and speakers and big
magnetic coils and even a pirate radio station. And we inject all of these
environmental signals to see what they might produce on
the gravitational wave channel. We're thinking about, okay, we see
a disturbance in a detector. Is it a gravitational wave, or is it just
some truck on the road or something? It would be astonishing. Astonishing,
if they left something at both sites.. Maybe they left some timed... So on the night of September 14,
that was our last day. Actually, probably September 13
was our last day, but we were counting the night as ours as well.
Nobody was here to stop us anyway. So at 4:00 in the morning we said,
“Should we do more measurements?” So we looked at our list and
one of the things we wanted to do was drive some cars around very close to the buildings, brake really hard every few seconds,
just to see if we need to limit traffic around the site. And we used
a little GPS synchronized watch to sync our so-called
injections to the data. So we say, "Okay, we're going to brake
every 5 seconds, start at zero." We're going to break six times
and then look for that comb of six kind of fingers of
noise into the data. But the GPS watch had desynchronized
and it was four in the morning and Robert at his flight probably at like
ten or noon or something. And we said, "Fine, You know, it's just not
that important. Let's just leave." Luckily, I think, because the
next day the emails started. They were here all weekend? Where were you? When did you leave?
What were you doing? I know for sure I was in the car
driving at 4:35 in the morning, and the event was at 4:50.
So everyone breathed a sigh of relief that I wasn't secretly climbing
on something at the time. This is the only experiment... Matt Evans led a team that eventually
would prove beyond any doubt that the detectors could not
have been compromised by what they called a "rogue injection.” Hello, everybody. We've all been asking
ourselves, "How could this signal, which appears so perfect, and so loud,
have appeared in the data so early in the run, and it all seems a bit improbable."
So I think it's reasonable for people to ask,
was it somehow fake? In the process of investigating
for rogue injections I went through and talked to people
all the way along the chain. And what I found was that
everywhere I looked along the way, there was somebody who had actually taken
great care to make a very secure system. Turns out the data spreads from
the interferometer very quickly, and so it's hard to add anything consistently
through all the copies that exist. And the security actually on the
computer systems is quite high -- which I didn’t expect for a science project.
So by the end, I was thoroughly convinced that it would have
required some large internal conspiracy of evil geniuses
to pull this thing off. I think it really verges on crazy
to think this was injected. I didn't feel that way when
I started the investigation. I thought there were ways
it could have been faked. The idea this might have been
a blind injection or some sort of, rogue injection, some hack
of the system. It wasn't that. But Anamaria and Robert's
clandestine night at Livingston will become one of the legends of LIGO,
not because they turned out to be Weiss and Evans' elusive evil geniuses,
but because, had they not stopped working only 15 minutes before the signal arrived,
history might have been very different. What we had been planning on doing
would have taken us right across the time when we made the detection, which was
only like 50 minutes after we stopped. It would have meant that people
weren’t looking for that signal, because we essentially say,
"Hey, we're injecting now. Don't believe anything you see." Had they had a burst of energy late at night,
they might have continued working through the time when the signal came.
That would have been a pity, because we wouldn’t have been able
to claim a detection if they had been up to no good at the time
in making injections. So the idea of the event is
we don't talk about the event outside of the collaboration.
We're trying to keep a secret, if you want to call it that,
with a thousand people. So we're inevitably going to get rumors
and there probably will be some questions. They might be unexpected. I thought,
I keep thinking, that somebody will say, “Oh, wait, I found something.
It's not it's not a real event." This is looking more and more real.
So this could be the real thing. It was either a double secret committee
that is testing us all, or this is ... We asked for a fire drill! I think everybody has heard that chirp noise and
all the people that have made the chirp noise.. This is a -- Time, Frequency.
And it goes, "Boop." It's a chirp.
It's very speculative right now. A lot of people don't believe this
because it looks so good. The degree of reality has gone up and up.
And so it will be very, very bad if we find out that this is something
you know, that, you know... So, I'm just now looking at the chat windows
and everyone is starting very fast. We've looked at a lot of the obvious places
already and we don't see this. And so right now we're in this unplanned mode
of essentially freezing status. And rather than have to apologize
for what we do months from now, it'll be good to know now whether people
are confident writing a paper with more data. This is the time to do the math, I think. But it's new territory.
We have an event. We have hundreds of people
looking at the event. People are going to look for any kind
of way to poke holes in this. There's going to be a lot of devil's advocacy
going on over the next couple of months, especially for something this big.
You would say, "What if we're wrong? What if it's a mistake?" When you're detecting something,
or claiming to detect something that's never been seen before, you have
to have a certain degree of certainty. If this was the 10th event we were seeing,
maybe we wouldn't care so much. We know they're out there.
Maybe we can live with an uncertainty, you know,
a lower confidence level. But for the first one, you've just got
to be sure that this didn't occur due to some other artifact, that this
is really a message from nature. You worry that in any complicated
experiment like this, that you may have made a discovery, but
you're not sure that discovery is really true. And, I mean, there's many situations
in my life where that's happened. You know your apparatus
better than anybody else. How could, you know, what could mess it up?
The main thing we're concerned with is just sealing off all the avenues of doubt,
which, of course, in science you do by being your own worst enemy. Gravitational wave detection is,
in some sense, a statistical statement, There's a possibility, for example,
that the interferometers could misbehave in such a way that that particular signal
could show up almost simultaneously on both interferometers.
So the job of the data analysts is now to understand how often that happens.
With what frequency, we might expect a false event to show up
and look like a real event. So the real challenge now,
now everybody's scrambling to try and vet this candidate -- to look at it.
And in some sense the job of the people that are analyzing the data
is to try and kill it. They want to do everything they can
to prove that this is not a real event. And if all of their efforts fail,
then it becomes something that we would announce the world
as gravitational wave detection. (MUSIC) Good morning, everyone.
I'm coming here at a time when everything's kind
of crazy in many ways. So I appreciate you taking an
hour out of your busy lives to listen to something that
I think is pretty important. But it's really, really an exciting time.
And I think everybody in this room should be pretty happy about all the hard
work that they've put in to get us here. So this is something that I took
from the Detchar summary pages, and this is certainly getting
everyone's attention. What you're looking at is the first possible
detection of a gravitational wave. And this was the signal that came into the
Livingston detector Sunday morning. There's still a long way to go before we
call this a gravitational wave signal. One of the questions that has come up,
many of you know we have this thing called a “blind injection challenge",
where there’s a team of people that surreptitiously inject signals into the detector. I have been asked a number of
times, "Is this a blind injection, a double super secret blind injection?"
The answer is no. This is not a blind injection. No one on my authority, on Gaby's authority,
or the authority of anybody in the senior management of the LIGO Laboratory did this.
So this could be the real deal. All right? I think we're still coming to terms with the
fact that we have seen a gravitational wave. For many of us, it's something that we've been
waiting for for decades and decades, and it almost had taken on a mythical
sense that will it ever happen? “Oh, it probably will, but it won't be
tomorrow or the next day. It'll be next year or five years later." And to see
that we've actually crossed that threshold is something that still gives me a shiver of
pleasure when I wake up in the morning and still gives me a shiver of fright that
we've fooled ourselves in some way. I don't think it's hit me yet. If the true and profound implications
of the September 14th candidate were slow to sink in among the many
hundreds of LIGO engineers and scientists, understandable because they risked their careers
on finding just such a highly theoretical and impossibly faint detection.
There was one young physicist at the Max Planck Institute for Gravitational
Physics, in Potsdam, Germany, for whom there would be nothing theoretical
or intuitively challenging about the candidate. September 14th was Serguei Ossokine's
first day in his new postdoctoral fellowship in numerical relativity: The field whose
calculations, using Einstein’s equations, are our only way to understand the
last few violent, chaotic moments of a binary black hole
or neutron star collision. Serguei started his postdoc on September 14.
It was clear that it was possible to do some numerical relativity simulation to
follow up the event and understand whether what we had seen really agreed
with the solution of the Einstein equations. I came in and of course met everyone,
all the postdocs, etc. got acquainted and talked
to the director, Alessandra, and then she told me
to come to my office. I tried to explain to him also
the importance of the confidentiality, before even telling him the story. And at the end I told him we might have
detected a very interesting signal. I was almost immediately asked, "Would you
be willing to do numerical simulations if we think that this is correct?" I was
thrilled, but also a bit anxious, of course. He took the work beautifully, and he started
soon after to run the first simulation. So I was, of course, one of
many people who did so, part of a big collaboration, which
has this numerical relativity code that hundreds of people have contributed to.
We know that numerical relativity takes some time to run on a supercomputer.
Depending on the configuration it can be anywhere between weeks and
months before you have an answer. Of course, numerically, I mean,
if we solve it on a computer, the only output is just numbers.
This is so far the only way to really understand what happens around
the moment of merger and afterwards. And to understand it better, intuitively
we decided to make some animations. So the movies in principle are based on
numerical relativity simulations. So this is really the simulation.
This is really the data. This is what it hopefully will look like
and hopefully will be seen. The problem with these computations
is that the computations just produce millions of numbers and there's
no way for the human brain to absorb these millions of
numbers and understand what's going on without
some sort of visual aid. And that's why the movies are made.
They're not just made for non-scientists to "ooo and ah" over. They're made in order
to enable the physicist, the researcher, to comprehend what's going on. If we hadn't had computer simulations
that told us what the predictions are for this domain, we wouldn't have had any
confidence in understanding the observations, because you could not compute those
waves emitted from that first merger using any technique except brute force
numerical relativity on a computer. Kip really helped spur the field
of numerical relativity and getting people to take Einstein's
equations and put them into software and simulate what would happen when
two black collide of different masses, two neutron stars, black hole-neutron star,
and so forth. Without those simulations, we wouldn’t
have a clue what those waveforms meant. But they have so much information in them. And they have information because of
the mathematics and the computation. The way that Einstein's equations are
written in textbooks is not the way that you can actually solve
them easily on a computer. The problem with Einstein's is it's more like
50 equations that you're dealing with. There were tremendous obstacles,
both in terms of understanding Einstein's equations well enough
to be able to solve them on a computer without having
the computations blow up. So in terms of understanding the mathematics,
but also in terms of the coding. You're trying to compute not how something
behaves in space and time, but how spacetime itself behaves when
it is highly nonlinear, highly dynamical. We're building a catalog of simulations of
black hole collisions that tell us just precisely what is the shape of the wave,
the so-called waveform. That catalog then will enable us to look
at an observed wave form and say, "Yes, that was a black hole where this
black hole has a mass ten times the mass of the sun, that one has a mass
17 times the mass of the sun." The issue of reverse engineering,
of seeing some waveforms and figuring out what's going on in them,
that's going to be exceedingly difficult. And we don't know
how to do that yet. Because we don't know in advance what the
masses of both black holes are going to be, we have to generate a bank of
templates that spans that space, that have many, many combinations
of masses so we'll have a template that is close enough to any possible
signal we might get in the data that the search pipelines can
accurately recover it. To do that means that we have to
generate these templates quickly and in the software. We can’t do
that with numerical relativity, because it would be too expensive. So instead, we use pencil & paper
methods and that allows us to generate very accurate waveforms. But it's not
perfect. It's not a complete model. It's not the full general relativity solution.
It's a close approximation to it. So the model search that
found the event used on the order of 200,000 templates. The last two weeks have been really
pretty exciting, you know, from the time when these online searches
picked up this very loud trigger, we've been through a whole series of
exercises to figure out what this was. And many of them, underlying them,
are self-doubt. We're like, "Could we have caused this
by our own ignorance or anything from accidents to, you know, to malpractice?"
And every check we've done has kind of come back saying, “No, this really came from
some astrophysical origin,” we believe. And so then you start almost believing it!
And that's pretty cool. The real difficulty with making the
first discovery was the history of -- I think there's probably been something like
15 papers published over the 50 years that we’re talking about, where claims to have
seen gravitational waves have been made and all of them have gone
into the waste bin. And for that reason, for these 50 years,
gravitational wave detection physics, or terrestrial gravitational wave detection
physics, has been a sort of orphan field. Everybody thinks that the people in it are
idiots. They’re doing something impossible. And year after year, they
demonstrate that it's impossible. And in the meantime they've got people
who are claiming to have seen the things and haven't seen them.
So it's had a very bad reputation. And so the whole field knows -- knew --
that to make the first discovery, they really had to do it right. Well, there was there was a moment
when I basically broke down in tears with the happiness of it all.
And it was a precise moment. It was the so-called "box opening" ceremony. We're going to listen to the Compact
Binary Coalescence Group, who’ve collected their data together in
this little snippet of an observation run. And they've done two things.
They've looked at the data when there's no gravitational wave signal.
And they've also looked at the same times for the two detectors.
And this foreground measurement, where you look at the synchronized
data from the two instruments, that's where a signal shows up.
So the collaboration, I, among others, are really impatient to see what's in the box. And
so we're going to probably open the box today. The first thing we're going to do though,
at 11:00, another half hour or so, is look at the closed box. We'll talk
about whether or not we understand the statistics of the detector
data to date well enough to draw any conclusions
from what we see. The opening of the box is a
process of them actually just walking over to their computer,
clicking on a button, and opening this data file and looking
to see what it says. So if there's nothing sort of further to say
on all that I will hand directly over to... We actually broke the teleconferencing
software that day, because it was set up to take 50
people and 400 people joined. And Alex Nitz will walk through
the upper box page. And then we have a discussion of what we do
about possible quieter events in the data. The thing which I think is really
maybe electrifying here is that there may be other
events in the data. There's always gravitational waves in our data.
This event is an extremely loud one, but the further you go away in space,
the more sources there are. These sources are constantly
producing gravitational waves and these are constantly in our data.
The problem is to this point, the noise of the detector, the terrestrial
noise, the noise of Earth, has been loud enough that it
covers up these these events. For people who are aren't CBC
or BRAK attendees, this is the primary offline deep
search for neutron star-black hole, binary black hole, binary
neutron star binaries. In the last few years I expect
that LIGO and Virgo will detect many more of these events.
Either black hole-black hole, hopefully also neutron star-black hole,
neutron star-neutron star. From each of these sources, we can learn
something different about the universe, about nuclear matter in extreme conditions,
general relativity, and so on and so forth. So when this happens, I think the most
important fact will be the transition between finding gravitational waves,
which is what we are doing now, what people are rightly focusing on
in the last several years, okay, So from finding of gravitational waves, to doing
something with gravitational waves, which is the exciting part. To prepare for the box opening, we wanted
to go back and have a high-level review of the entire code. So the review
started about over a year ago. The things that are the most kind of rewarding
are sometimes the things that are simplest. And that’s, you know, kind of the opposite
of what people think is interesting. I started out with things like trying
to stabilize lasers very precisely. And trying to build electronics that have
very, very little noise. And things like that. But some of the really most difficult
stuff is kind of the dumb stuff like vacuum -- getting a good enough
vacuum for the beams to go through, getting a good enough vacuum so the
mirrors don't get contaminated. It's been a huge amount of time on that.
And that is really, really hard, because it's got all kinds of things:
The history of the steel. it's got all this kind of stuff that
you just can't control well enough. And it falls into one of these domains
that is sort of a black art. We are signing off on being okay
with the box being opened? So during the telecon, people were just
sort of presenting the background, or the work they had done to come up with the
background estimates they had come up with. And then when everybody's confident,
"Yeah, that looks good." They don't see any real errors or issues
with the way you set up your analysis. "Pipeline A, yeah looks good." Same kind of thing:
"Pipeline B yeah, that looks good." Then everybody says,
"Okay, now that we're all satisfied with the way you've
set up your analysis, we're ready to actually see what your
analysis has come up with." And that's the opening of the box part. For the box opening we've reached a strong
consensus that we're ready to open the boxes with no major objections
from the folks on the call. Then yeah, we said,
"Okay, we're ready." Let's take one final round of
questions from anyone on any of the things
you've heard so far. We asked for objections:
"Does anyone have any reason why we shouldn't be
looking at this?" And everyone said, "No."
So we went ahead. I guess now, unless there are any objections
we can go ahead with the box opening. So Alex NItz, if you could take us
through then the opening. We flip the switch. So there was like a precise moment.
We could probably time it to the second when everyone saw how how strong
the signal was compared with the noise. And we could scroll down to one particular graph,
a histogram of the strength of the signal... Yeah. And there it is. ...versus the strength of all possible noise events,
shown in such a way that you could see how unlikely it was that
noise made this event. We'd all had enough practice at box openings.
We knew exactly what criterion would say, "There's not even one chance in a million
that noise was responsible for the signal." And that's the standard that physicists
have developed for saying, "Okay, if it's better than one chance in
a million, it's alright to say it's real. You found it." And it was right there. It was like a dream. So when the box opened today,
well, there were two boxes. So the first box was opened and there
was the event loud as can be. But my eyes went immediately
to all the events below it, because we expect somehow that nature
wouldn't give us just this one loud event. But there'd be this whole popcorn of
smaller, less loud, events lurking about. And there wasn't much evidence of that.
So I was thrilled the event was there, and I was a little disappointed
that was the only one. This is a little bit spooky.
But we have to make one step at a time. Take what nature
gives us. But keep those questions alive. Well, look, to be honest with you
what's the disappointment? Why do I have a disappointment?
It's not just me. Everybody in the room is very proud that it was there.
But the thing many of us were looking for is the fact that, my God, if you have this very
sensitive way of looking for this, there should be a population
of all of these things. They're not just, why only one of them? I think this is one of the biggest mysteries
that we have to actually solve in the weeks to months to maybe years.
I don't know how long it'll take before we see more events and can start understanding
what does nature really have out there? You know, right now we've seen one event.
It’s tantalizing. It's actually magnificent. It's loud. It's a system that we haven’t seen
before. So nothing could be better, except if we had more of them. No, but I think that discovery isn't the
measurement of the gravitational waves. I have to tell you that.
It's the black holes. That's absolutely spectacular. And not just solar massey ones,
but tens of solar massy ones. No! And this exists. And if you see a couple more
then you could say something about the universe. It's something new we're going to be
able to say about it, which is spectacular. To me, that's the big discovery. Yeah, but then it's going to be hard to say,
"Well, but the universe only has one of these!" I think the remarkable thing is not so much
that we saw a gravitational wave. I mean, that's remarkable enough,
but it isn't the real centerpiece of this whole discovery. That centerpiece
is the fact that we saw a particular source that nature seems to have given us,
which a lot of us have thought about over the years. It's the best source
we could have imagined. It's the source that says Einstein is right
on every goddamn detail almost. In other words, this is a source
that doesn't require any other physics than general relativity.
Let's think of that. The idea of LIGO came to me
in a course where I was trying to explain to the
students general relativity. I barely knew anything. I mean they knew
more than I did in most of the course. There was a revolution going on in the
whole idea of gravitation in the early 60s, and I wanted to be part of it. And
because I had spent time at Princeton, they thought I knew something about
general relativity, which was absurd. The trouble was, I couldn't admit to the guy
who asked me to teach GR here at MIT that I didn't know anything about it.
I mean, I came to MIT with this whole big program of doing things in
gravity, and then to admit that I didn't know what the
hell the theory was about was probably more than I
should have admitted, right? So I was one day
ahead of the students, in many cases just about
equal with the students. So it was an interesting term, let me
tell you. And I learned a lot. Rai did an analysis of all the noise sources
that such a gravity wave detector would have to deal with. Basically
created a blueprint for the future. But it is probably the most powerful
paper of its sort that I've ever read in terms of a vision for the future.
And this is 1972, after he's been thinking about this for a few years. What then happened was
sort of an interesting thing. I was at that time deeply connected
with NASA because I was doing ballooning for the cosmic background radiation
and stuff like that. So they asked me to run a committee in 1975
to look at what the space program could do for gravitation and what at that
time was called experimental relativity. Kip Thorne, who I'd never met before,
came to tell us about what he was interested in, in experimental gravitation. I picked him up in the middle of the
summer. This was in Washington. I don't know if you ever go to Washington,
you realize you can't find any place to stay in the
middle of the summer. So he and I spent an evening and a
night together in one motel room. And we talked all night.
And I mean literally all night. And what was Kip up to at that time?
Kip had probably, as far as I was concerned, the premiere group in the world
on general relativity. If you look at the names of the
people that were in Kip's group, they now illuminate the whole field.
A spectacular group that he had put together. He had not heard of interferometric
detection of gravitational waves. It was new to him. I was very skeptical because
I didn't really understand at all how this was going to be done
to reach the levels of sensitivity that we needed. You're trying to make a
measurement of the motion of a mirror at a level of accuracy that is
one-ten billionth the wavelength of light. Ten to the minus 21 was a number
which we designed LIGO for, which means a change in length
between the two mirrors. Okay? It’s a frightening number. People looked at that and they thought
"This is ridiculous." And I looked at that when I first heard about it,
and I thought it was so ridiculous that I wrote a little sentence in a textbook,
a classic textbook, that I had coauthored called Gravitation with Charlie
Misner and Johnny Wheeler, which said, it seems unlikely
this is ever going to work. And then I spent much
of the rest of my career trying to help the experimenters
make it work, because I looked in depth at Rai's
analysis of 1972 and I saw it is feasible, but it's going to
be extremely difficult. The estimate was that we had
in 1978 was ten-to-the-minus 21 would be where pay dirt is. The
gravitational waves that were discovered, the announcement made
precisely one month ago. The strength of those waves was
ten-to-the-minus 21. It was right on the money. We even
had t- shirts at this conference where we agreed on what is our goal:
"ten-to-the-minus 21 or bust." This is 1978. Seventy eight. That's basically
40 years ago. 78, 88, 98. Now that's the only way I
can do math. 40 years ago. The book that Thorne, Misner and
Wheeler wrote, “Gravitation,” has been the Bible of gravity
wave science even longer. It first came out in 1973.
John Wheeler had helped launch the search for gravitational waves,
among his many pioneering achievements. But it was a different, more primitive technology
than Rai and Kip talked about that night. It was called a resonant bar detector, and its
most famous experimenter, Joseph Weber, would become both one of the most
famous physicists of the late 1960s and early seventies and then a pariah
among his physics colleagues. You'll get different opinions on this,
but my opinion is that without Joe Weber, we wouldn't be here. There would
have been no gravitational -- nobody would have done
anything as mad as try to detect gravitational waves with terrestrial
detectors. It's basically impossible. So this is an artifact. It's one of the bars
that Joe Weber used in the 1960s. Joe was the first person to take seriously,
as an experimentalist, to try to actually make a detection of gravity waves.
And so what we have here is a very large aluminum bar, which is suspended.
You can actually see it moving. The theory was that if a gravity wave comes
by and space expands and contracts, that energy would be released
as a sound wave in the bar. Joe was a controversial character,
and people don't give a lot of credence to his claims that he had actually
detected gravitational waves. But to me, Joe is a hero because even though
he's a model of what not to do in data analysis, he was the person who had the chutzpah
to go and make this first attempt. If it wasn't for that pioneering work,
we might well not be here. And he did think of many of the ideas that
we would later incorporate into our practice. The laser Interferometers really
started in the early 70s and there were developments
in many places in the world. The first real prototype of a gravitational wave
detector with laser interferometers, suspended mirrors, and all the major parts,
was built in Munich by the Max Planck group. My predecessor in my Max Planck
job, Heinz Billing, was one of the first one, two,
three people were actually tried to experimentally detect gravitational
waves half a century ago. Heinz Billing was already famous in Europe
for having designed the first magnetic storage system for computers. And then in 1952,
building Germany's first electronic computer. Billing got involved in gravitational wave
detection when he was asked to test Joe Weber's claims in the U.S. That's what he did. He said, "I will copy the
Weber cylinder just as closely as is possible.” At the same time, at the University
of Glasgow in Scotland, Jim Hough and Ron Drever also
built and tested a bar detector. And with all of this effort, no
gravitational waves were detected. So the outcome was, of course, clear:
Something needs to be done to make these detectors more sensitive.
And Billing said. "Why not try what Rai Weiss is proposing at M.I.T.” Rudiger was the last senior member of the
German group that was so important in developing the techniques. They made the first,
really, I would say, well-tested prototypes. So what happened?
I'll tell you what interesting happened. They, the German group, took
that whole idea and ran with it. And with my blessing by the way.
Billings, who was the head of the group, calls me up and says, "Have you
got any graduate students who are working on this
very good idea you have." And I couldn't believe it. But then
I said, "Well, at the time I don't have any graduate students working out,
because there's no money for it." "Well, is there anybody?" And it turns
out later on there's David Shoemaker, an exquisite experimenter,
I mean, superb experimenter. David went to Europe and
actually worked with the Germans. I had been working here in the lab
with Rai and colleagues on a small gravitational wave
interferometer in the early 80s. It was clear that he really grasped all the technical details very quickly.
And so made his very good contributions, due to his ingenuity
and due to his youth. Honestly, they were a little bit
tired of working together. They've been working so long on these projects
that they'd just lost a bit of the spark. And I was the ingredient that they needed.
I knew nothing. I was full of questions. And I was full of energy. And I was
able to just fall into the group. So I often found myself
working all alone on weekends. The Germans were not working on weekends.
And would surprise them on Monday morning with a bunch of findings that
I couldn't explain -- and they could. And he was the guy who
actually got them going again. And there's an absolutely wonderful paper
that he wrote with all of them. He's the lead author of that paper. The collection of noise sources that Rai
had mapped out in 1972 as a guide, trying to measure each one of those in this
instrument, we were able to come up with something that really brought
the field forward, I think, in a way, and gave people a lot more confidence
that we could build sensitive instruments. Very important: The German
confirmation of these ideas, that they could make a thing work
at the theoretical limit. It was really spectacular
what they did. I felt confident that you could
take it and extrapolate it. I saw nothing that would stand
in the way of that, short of money. In the summer of 1988,
Kip Thorne, after a number of years, convinced me to move to Caltech
to take on this type of research. Kip was an extraordinary popularizer.
He would go around and grab everybody and beat them over the head
and point out to them that this was such an important problem.
It was like going to a revival meeting with this incredible preacher
throwing fire and brimstone at you. And you had to go away convinced that this
was really worthwhile and exciting and hard. We took a lot of great work that had
been done long before I joined and used that understanding
to write the construction proposal to build this big, gigantic,
monumental thing. And we faced all the problems of, you know,
trying to get NSF to bet the farm on this, which is what they did.
Very brave people took this on -- a project that was ten times bigger than anything
NSF had ever done before. Very high risk. The thing that surprised me the
most n all of this has been how the National Science Foundation
came to support this, to take such a big risk
and then to stick with it. The 1989 proposal was written by Robbie Vogt,
who had been a provost of Caltech and came on as the LIGO project director.
He was joined by Kip, Rai, Fred Raab and Ron Drever, who had been a leader of the
important Glasgow gravitational Wave group and had come to Caltech to join Kip
and Rai as one of the founders of LIGO. And then what happened was that
there was a significant falling out between Ron Drever and Robbie Vogt,
which was most unfortunate. So what happened is that caused
all sorts of hell to break out loose. It was in every newspaper that this terrible
thing had happened to the LIGO project. It got busted up. The director of the NSF informed the Congress
that they were halting, interrupting the funding for the project,
which is a very serious act. And they told Caltech that the leadership
of LIGO needed to be changed. So Barry was asked to be
the new director of LIGO. Barry was a absolute breath of fresh air,
in the sense that he had been through it. He'd been through the SSC.
He knew how to run a big project. He knew how to deal with people.
He just knew exactly what he needed. And little by little, the thing took on
the feeling of a real project. I think it's quite clear that if Barry hadn’t come
along and brought his talents and skills to LIGO, it would have crashed and burned.
We were in a in a crisis. We were approved in 1994 to build LIGO.
And it took five years to do the physical building, which is maybe only a year longer than I thought.
It took five years to make it work, which is five years longer than I thought,
really, because it's very, very difficult and there was no precedent. At that time we knew that the technology
didn't exist. It would have to be invented. Advanced LIGO uses glass which is so
beautiful I don't even have an analogy for it. But it's so purely made
that if you set it to ringing, not that you would do this,
but If you whacked it like this, it would ring 100 million times
before it stopped vibrating. And that's because it's so pure.
The energy doesn't go anywhere. In order to detect gravitational waves,
we had to push technology so far that the risks of not succeeding right away
were great enough that we didn't have the nerve to try to sell the whole thing at the beginning.
And I don't even think the NSF, which is the only funding agency
that would fund this thing anyway, would have taken it on.
So what we proposed was to build a first phase of LIGO
that had the whole infrastructure for the eventual LIGO. And had
all the techniques that you need and sensitivity to take it seriously.
Sensitive enough so detection of gravitational waves was possible.
So the keyword was possible. And it's really what was behind us
doing it in two stages, too. It is not just the risk in selling it, but the risk in
ourselves learning how to do it and doing it. Initial LIGO ran until 2010. Then LIGO would virtually tear out
the insides of the two detectors and build Advanced LIGO from the
ground up, inside the vacuum chambers. Let's start from a baseline
that we did initial LIGO, which wasn't sensitive enough.
Gravitational waves weren't detected. What did we have to do to get
to where Advanced LIGO is? There's a lot of little things,
but there were three big things. One was that in order to get more sensitivity,
we wanted to have a laser that was at least ten times or 20 times more powerful
than the laser we used in initial LIGO. This high power laser is unusual,
it's very highly stabilized. You're hitting a target that's about
this big after four kilometers. And you don't want just to hit it somewhere.
You want to hold the beam very stable. There are no lasers on the shelf that do that.
So we had to develop that in the laboratories. It still may not be solved,
but we think it is. So that's the first. The second is that
at the lowest frequencies, we're limited by the shaking of the earth,
what we call seismic background. Our mirrors are sitting on the earth
in one way or another and are shaken by seismic noise, whether
it really comes from earthquakes and waves on ocean shores, or from people walking by,
or trucks rumbling down the street, or airplanes going overhead. And all
of those things need to be filtered out. The very first stage of that is this HEPI system,
the Blue cross beams you see and actuators. Each one of these four piers effectively
holds up the 6,000 pound payload inside the vacuum envelope.
And that system can move. If the ground moves one way, they move
the chamber the opposite direction. And now under our Advanced LIGO system,
we actually have all of these chambers linked so that if the ground is moving one direction,
they’ll move the chambers the opposite direction and keep everything
still relatively. The third is to try to make the mirrors themselves
not a noise source. This was done beautifully by Jim Hough and our Scottish collaborators
at University of Glasgow. The mirror themselves in LIGO
have to be delicately suspended, isolated from all sources of noise. My work on that was in the area
of the silica suspensions to make these super low-noise, all-fused
silica, all ultra-pure glass suspensions to hold the mirrors
of the interferometers almost motionless, just waiting for
a gravitational wave to pass by. There's a little thread coming down here.
Can you see that? Right, right on the tip of my hands.
It's hard because it's glass and it's so tiny. It's a little bit less thick than a human hair.
But these things have crazy tensile strength. So these are the suspensions
of our LIGO mirrors. But that itself has to hang from
several stages of isolation, because one stage isn't enough to isolate
from all the noise to hold that mirror steady. So the Advances LIGO suspension is,
in fact, a quadruple pendulum. So that's four stages
to get the necessary isolation from seismic noise,
or seismic vibrations. Norma did a lot of work and took responsibility
in the whole collaboration for being the head of looking after that process.
Norna doing important parts of the design of the global picture,
bringing it together to make the four-stage pendulum,
which was one of the things that we in the UK, Glasgow, helped deliver
as our contribution to Advanced LIGO. For me, I have to say that this is a very exciting
time that we might finally achieve something which I was hoping to see when I started off
in gravitational waves many years ago. We're where I thought would be
maybe ten years ago. (MUSIC) We've talked about the displacement
of the arms and how small it is. That might make you think
that the event is very weak. But when the signal reaches us, it does
produce this tiny distortion in spacetime. And part of that is because
the source is so distant. But nonetheless, it carries a lot of energy,
this gravitational wave. The actual source of these two
roughly 30 solar-mass black holes in the final last milliseconds
of that system's life, the black holes are racing
around each other, distorting up spacetime, merging
and forming another black hole. And in the process converts about three times
the mass of our sun, three solar masses, in about two tenths of a second
into gravitational wave energy. So that makes it, we think, the most energetic
astrophysical object ever detected. Take every star in the universe,
add up all of its power that it produces. In every galaxy, so I'm talking
about the whole universe here. The event that we saw on September 14th
was 50 times, 50 times more powerful. Basically, the universe got 50 times
brighter in gravitational waves during that brief instant
where it came together. If you imagine that every star in the universe
had a planet orbiting around it that was similar to the earth.
There’s about, I think there’s about a billion galaxies in the universe.
There's about a billion stars in each one of those galaxies. So if
each one of them had an earth orbiting it, and if each of those earths, if the populations
on those used about as much energy as the earth's population used in 2014,
in every form, this single event that gave us this little burst
that lasted a fraction of a second put out enough energy to supply all of
those earths for over a billion years. We've done something different than
has been done before, right? This is certainly the first time that we've seen
the stretching and squeezing of spacetime due to a passing gravitational wave,
or any other effect for that matter. It's the first time we've had an instrument
sensitive enough to make that measurement. And it's the first time we've been
fortunate to have a source that had the force needed to make the
signal that we could measure. Earthlings have experienced
quiescent warped space before and the warping of space
in the form of the deflection of starlight going past the sun, for example,
and other experiments in the solar system. What we've never had until
LIGO is any information whatsoever, observationally,
about this highly, highly dynamical warping of space and time associated
with these gravitational waves. There you see the black holes
going around each other. It's a beautiful display
of gravitational lensing as they go around each other. They're going
to collide and merge into one black hole. And they're getting close. The collision
and merger is extremely violent, but you don't see the violence
so much in this movie. The collision has occurred.
It's ended. Gravitational waves were emitted and
they're traveling to Earth. To really see what was going on,
you have to go up into a higher dimension, go up into the fifth dimension,
look in on the warped space in the orbital plane
of the black holes. Here are the black holes, these funnels. The color
coding, as before, represents the slowing of time. And this is the gravitational wave form
that is being emitted. You see the blue point is where it is on the shape of the
waves of stretching and squeezing. And we're going to watch the warping
of space become very extreme, end of time become very extreme
during the merger. I'll pause it completely at the moment of merger.
That's what it looks like at the moment of merger: Tremendously warped space and time. About half the stars you see in the
night sky are actually binaries, pairs of stars revolving around
each other. And so people thought there may be binary black holes in the universe.
They had never been detected before. But this is what was detected
on September 14th. It's a significant event, let's put it this way.
And nobody has this yet dissuaded us of that. That's the elegant part of it.
I mean there are enough skeptics in a group of 900 people like we call
the LIGO Scientific Collaboration that there would be somebody
who says, "Look, this is all baloney." And I haven't heard that yet from anybody.
I talked with Kip Thorne a couple nights ago about this. This is the best thing
that could have happened to us, rather than seeing a neutron star.
We'd like to see those for other reasons. But here is the thing we really
want to see is a black hole, a pair of black holes
making a new black hole. These theories are pretty extreme.
Black holes are very extreme. There are all these kind of spooky
aspects of the black holes, which from a physics perspective
makes them fascinating, a little terrifying. So a black hole is an object that's not
made from matter like you and I. It's made from warped space
and warped time. And yet it is an interesting richness of structure
like you have in things that are made from matter. When two black holes collide, they create
a real storm in the fabric of space and time, with wildly oscillating rate of flow of time,
with vortices of twisting space. We're essentially seeing them up close.
150914 was an event where we took two of these and we crashed them into
each other at almost the speed of light. That's a really good way to figure
out what they're made out of and whether they really are
what you think they are. And they are! They are exactly
what Einstein said they should be. Unbelievable. You can't ask for more.
It's the vindication of everything. It was this massive cataclysmic event,
billions of light years away in space. These two massive, dense, giant objects in
space, they were black holes billions of years old, Each one weighed more
than 30 solar masses. They were hundreds of kilometers apart,
revolving around each other hundreds of times a second,
until a third of a second later -- not even time to blink, they collided. They were
brighter than the rest of the universe. It was the most cataclysmic event
that I can think of! In mid-October, a second far weaker signal
sweeps through the two detectors. When we got that second weak signal,
that's when I really finally accepted, "Oh my goodness, there is actually a
population of binary black holes out there. And this is happening for real.
And we're making real discoveries." We're opening a brand new field of astronomy.
We're discovering binary black holes that electromagnetic astronomy could
never have seen before. And the only way to discover this population
is through gravitational waves. And I'm part of this
historic discovery. And I just couldn’t believe this was actually
happening and I was experiencing it. It is definitely another candidate,
but it doesn't meet LIGO's threshold of one chance in a million
being a false alarm. The second signal was never
claimed as a strong detection. And the reason is that October event had a
roughly 85% probability of being astrophysical. And that sounds like a high probability.
On the other hand, that leaves about 15% probability
that it is noise. And from a scientific point of view, 15%
probability of this being noise is too high. We discovered for the first time
a pair of two black holes colliding. We opened a brand new field of astronomy,
and we're making this claim based on one source that nobody has ever seen before.
No independent other team has seen, and no other team can ever see again,
because this signal reached our detectors, it lasted point two seconds
and it's gone. Nobody can come a year later,
look at that part of the sky and say, “Oh, yeah, I see that signal, too,"
because that signal is gone. So we were in a position
of having to make this amazing claim, changing
the field of astronomy the way we know it, and
all based on one source. So what do you do? You go by what
you are trained to do as a scientist based on your statistics. You can't let
yourself ignore the statistics and go with, "Oh l'd love to
have two sources, so I'm going to use the low
statistical significance signal just because I'd rather have
two to make my claim." You have to be honest, based on what
the data are telling you, of course. The October event is not claimed as a detection,
even though LIGO faces the prospect of announcing to the world its first detection
without having found another. A prospect many in the collaboration
view with very real concern. But then a week after our interview with
Mike Landry at Hanford, Christmas night in the U.S. or Boxing Day in Europe,
the two photodiodes at both detectors light up within just over a
millisecond of each other. And LIGO makes a second
verifiable detection. (SOUND OF THE TWO “CHIRPS”) You know, it wasn't 100% sure.
It wasn't even 90% sure that we should have another.
But when we got the second one, we all said, "Ah, this is for real!"
I mean, we all felt, not just excited, but relieved, too. It's difficult to describe
that because everything was different, but also so reassuring.
Both of these systems were at a similar distance,
1.3 billion light years away. Very, very far in the past
and far in distance. So, the second detection really tells us
the first detection wasn't a one-off thing. It wasn't lucky.
It wasn't a fluke. We can see these things with LIGO.
LIGO is real. We're no longer a physics experiment
detecting a gravitational wave. We're doing astronomy. That's
a transition to a new world. Kip Thorne wrote in his book on
the science of the movie "Interstellar," a film he was instrumental in creating:
"When the shape of space is oscillating wildly and the rate of flow of time
is oscillating wildly, for me, this is a fascinating
frontier of knowledge." LIGO is now on that frontier. So where is this heading?
Well, we've painted over the years a picture which is pretty complete.
And that is indeed a picture that a lot of it depended on Kip. Kip was sort of the visionary
in what sources might there really exist. If we look into the future of gravitational wave
science, we will have a future that involves studying things like colliding black holes
that exist in the universe today. We also have a future of observing what was
going on in the earliest moments of the universe. The ultimate holy grail of gravitational wave
astronomy is probing the Big Bang. Gravitational waves are the only
form of radiation that is so penetrating that it would travel unscathed
through the very, very hot and dense material in the earliest fraction of a
second of the life of the universe. So if we are ever going to actually
see the Big Bang, the only way we will actually see it
is through gravitational waves. To see this signal from the early universe will be
certainly the greatest discovery ever, because we will bring back a snapshot
of the universe at a very, very early time. At a time much earlier than when the
Cosmic Microwave Background radiation was emitted that today
we measure very well. We can see back to when the universe
was about 400,000 years old, 380,000. Before that the matter in
the universe was so hot and so dense that photons,
light, was trapped. So with light, we can only
see the universe back to an age of 380,000 years. Gravitational waves are produced basically in a
fraction of a second after the Big Bang. And so we will have a snapshot of
what the universe was at the time. This is absolutely phenomenal.
This is the ultimate form of cosmology. Understanding the beginning. Perhaps the most exciting is the unknown. In the era when we were trying to convince
people that LIGO should be built, for me, this was the most exciting thing:
Is the likelihood that we will see waves from a phenomena that we never dreamed of.
After all, every time a new window has been opened on the universe,
unexpected things have been seen. And this will surely
not be an exception. This is such a bizarre window
compared to everything else that... It's like Galileo you can say opened up the
window of optical telescopes. But we can see! We have eyes! Perhaps safe to say that no
creature on earth has ever observed gravitational waves before, or experienced it
through their senses or any other way. So this is completely something
which is outside of our intuition. The wonderful thing about LIGO is
because it's new, we're going to see things that we don't know about.
And my hope, and sorry Albert Einstein, but my hope is that we're going to find out
why your theory isn't quite right. Okay? We're going to be able to break
your theory at some level. And I'll be honest with you,
I'm not going to bet against you. But, Albert, at some point your
theory is not going to be right. And I'm hoping we're
the ones to prove it. I don't think it's likely
we will discover that. But things that I thought
were extremely unlikely have come to pass during my career, such as
the discovery of what's called the dark energy, the accelerated expansion of the universe.
Tremendous surprise to me. So I've been wrong before.
I could be wrong now. I think the odds are not high. But boy
it would be exciting if that happens. The dream of every scientist is to
break through a barrier, to be able to see for the first time things
people couldn't do before, you know? And so moments like that are the
first look through a telescope. The first look
through a microscope. And for us, the first touching
of space and time, if you will. I thought I was in a dream.
It was just fantastic. I cannot yet believe it. For five
months we kept this secret. And during the last few days, I was
thinking I don't want to give it away, because it was so nice
to just have it there and explore it and look at it
and analyze it. But I think it's the right time now
to, you know, let it go so that other people
can know about this. Good morning. Without a doubt the reason
so many of us are here today is because we believe in the potential of the Laser
Interferometer Gravitational-wave Observatory. Opening a new observational window
would allow us to see our universe and some of the most violent phenomen
within it in an entirely new way. Ladies and gentlemen, we have detected
gravitational waves. We did it! I am so pleased to be able
to tell you that. It's really, really exciting. I couldn't be more excited.
My flight got canceled last night, so I was stuck down in New Orleans.
And I thought, "I could rent a car. I could get here." And one of the fellows
next to me in the waiting area says, "Oh, but you'll fall asleep.'
I said, "Oh, no, I won't." Oh, I have waited 22 years for this.
I am not going to fall asleep. The frequencies of these waveforms
are in the human hearing range. We can hear gravitational waves,
we can hear the universe. Now, I wanted to play the gravitational
wave for you to hear. (SOUND OF THE GRAVITATIONAL WAVE) Did you hear the chirp? There's the rumbling noise.
And then there's the chirp. That's the chirp
we've been looking for. We're seeing something that has
never been seen before. And today, a lot of people's
dreams have come true. What we do is we suspend
the mirrors from a pendulum. Here is a sort of demonstration pendulum.
And here's the mirror. And my hand will be the ground motion.
And you notice if I move it very slowly, or at low frequencies,
the pendulum follows me. It follows the ground motion completely.
Now, let me wiggle it fast, and you'll notice the pendulum
stands still while I'm wiggling. That's the basis of the idea. Now that's
done with a tremendous elegance and, you know, with
cunning in this picture. This is what's actually in the apparatus.
You see it on the screen now. Okay? And by the way, the principle I just showed you
is very much like the principle in a car. It makes you comfortable in a Cadillac
and sort of bumping in a truck. Colliding black holes are not the only source
of gravitational waves that LIGO will see. We will see gravitational waves
from spinning neutron stars, stars the size of Washington, D.C.
made of pure nuclear matter weighing more than the sun,
with little mountains on their surfaces that, as the stars spin, those mountains
generate continuous gravitational waves, long lasting gravitational waves.
We'll see gravitational waves from black holes tearing neutron stars apart.
Gravitational waves from neutron stars colliding. We are searching for gravitational waves from
the central core engines of supernova explosions. And amazingly we're searching for gravitational
waves, and have some hope of finding them, from cosmic strings: Giant strings
that reach across the universe. Einstein would be beaming, wouldn't he?
This is obviously a very, very special moment. It's a very special moment for me personally
to be able to hug a faculty mentor when I was a graduate student at Caltech
and hearing Kip and Virginia Trimble, the spouse of Joseph Weber, inspire us
students with stories of black holes, which seemed imaginary at the time. And look,
look where we've come now, just amazing. So this thing stood out like a sore thumb, and
that made us all, and me certainly, suspicious. Personally, I wanted to represent the engineers
and physicists who are female and strong and bright, and I wanted to
stand up for Girl Power. You know, this represents 16 days of
coincident data at the start of the run. And you get one source that's a real home run.
Then imagine an instrument much more sensitive that's supposed to run for
six months, let's say. You know, we're not going to
know what to do with it. Nine months later, LIGO began
its second observing run. But by July 2017, 22 months
after the first detection, the euphoria of February's historic announcement
and its wide international media coverage had faded a bit. And it had also given way
to a disquiet, even fear, for LIGO's future. There had been another detection of
colliding black holes back in January, an event nearly 3 billion light years away.
And then one in June. But nothing more. And the detectors were plagued
by unexpected setbacks: Unanticipated flaws in the high-power laser,
and disturbingly, in the mirrors. And then there were the whims of nature
and even unexplained mysteries. We almost blew it. We were going to
shut off our detectors in June of 2017, and a decision was made to,
after a lot of careful consideration, a decision was made to run through August.
And that decision was influenced by a number of things, one of which was
we wanted to run with Virgo and have Virgo be able to say, "Okay."
You know, they participated in O2. I think that was very, very
important for them. Virgo is the three kilometer Italian-French
interferometer outside of Pisa. Its second generation, Advanced Virgo,
was late coming online. It was now scheduled to launch in early
August, joining for just a few weeks LIGO's second run, before its
planned shut down on August 25th. With multiple detectors about the globe,
they will be seen in one detector first, another second, another third.
And that time of arrival allows you to triangulate where that object
would exist in the sky. And the promise of doing that,
and localizing it in the sky, means that we can follow up with other
observational instruments: Light telescopes, radio waves,
x-rays, gamma rays. But LIGO's difficulties weren't over. On July 6th, a 5.8 magnitude
earthquake in Montana hit the Hanford detector.
Hanford was not only knocked offline, it suffered damage that could not easily
be explained or quickly be repaired. Hanford is broken at some level.
I mean, it's not performing anywhere near where it should be performing.
We don't completely know why yet. And so we're going to have
a lot of work to do. Virgo went ahead and came online
three weeks later, on August 1st. And then, amazingly, in further proof that
LIGO was on a truly charmed roll, on August 14, Hanford, Livingston & Virgo made
the first three-way gravitational wave detection. And that was only the prelude.
On August 17, just a week before LIGO's second run was coming to
an end the spectacular happened. What we know is there was this loud ping
in the gravitational wave detectors at the same time as there was
this burst of gamma rays. And this bright thing came up
in the optical and is now fading. And that's what we
know at this point. A month earlier, Virgo wouldn't
have been part of this. We would have had a large area of the sky
and we might have missed it. A short two months later, France
Cordova and Dave Reitze took the world stage again at the National
Press Club in Washington. Today we're thrilled to announce that scientists
have detected gravitational waves coming from the collision of two neutron stars,
the smallest and densest stars. This event occurred 130 million light years
from Earth in a galaxy far away. We have, for the first time, seen
both gravitational waves and light from the collision of two dense
dead stars called neutron stars. However, to do it this time,
we joined forces with thousands of astronomers and many,
many observatories. We saw a signal at 8:41 a.m.
Eastern Time on August 17th. (SOUND OF THE SIGNAL) The signal was much different from the
black holes that we had detected before. It was much longer.
We analyzed this signal and what we found was that
it was a neutron star approximately 1.6 solar masses
colliding with a second neutron star approximately 1.1 solar masses.
So this graphic that you're seeing here is just the brief second where they collided.
Binary neutron star systems have been predicted for decades, and we
knew that we would see them. What makes this event so amazing is
what came next: The emission of light across the entire electromagnetic spectrum,
revealed to us by a campaign involving 70 observatories, including
seven space-based observatories and every continent on the planet.
So if you look at the graphic carefully that I'm showing, you'll even see there's a
dot in Antarctica. So this is quite dramatic. We were able to identify it quickly and then
have astronomical partners following it up. You know, here we are, they happen
once a day somewhere in the universe. And we don't really understand how,
you know, what the inner engine is. What’s really powering them.
They’re tremendously bright. We see them to the edge of the
universe, just this burst of light. Where is it coming from?
And the gravitational waves teach us. The gravitational waves let us, in effect,
peer in right to the heart of them. And that's what we're doing. So we’ve now
looked right to the heart of one of these things. And we can tell you it's definitely
these two objects colliding, and that's what caused it.
They collided, two seconds later there was
this burst of gamma rays. So, I mean, that's remarkable
that we've had that. We've never had a picture
like that before, where we're looking to
the very inside of the event. Now, let me tell you what we saw
was two neutron stars, which are stars that are
the weight of the sun, about the weight of the sun,
about the size of Manhattan. Okay? That means you're dealing with
something that's enormously dense. And a teaspoon of it, If you
stuck it in the in that material, would weigh millions of tons,
You couldn't lift it. Astronomers have thought for a long time
that the collisions of these neutron stars produce heavy elements.
And there's been hints of that. As these neutron stars come together,
you begin to see that it looks like maybe all, maybe not all, but certainly most of the
very heavy elements are made in those collisions of two neutron stars, like for
example, platinum, gold, lead, uranium. They just didn't easily make in stars.
People had guessed at that before, but now they saw that
it was two neutron stars. They got that from the
gravitational wave research. This is my great grandfather's gold watch.
It's about 100 years old. The gold in this watch was very likely produced
in the collision of two neutron stars approximately billions of years ago.
We don't know exactly when. The universe has been expanding since
the Big Bang. And the bigger it gets, the faster is expands.
The Hubble Constant is the quantity that sets the scale for this expansion.
And astronomers have been trying to pin down this number
for more than 80 years. What LIGO and Virgo have done,
using this latest data, is to introduce a new method
completely independent. This is a method that was first proposed
30 years ago by Professor Bernard Shutz who is here in the audience
with us today. And the idea is to use the signal,
the gravitational wave signal from the two neutron stars,
to measure its distance from Earth. And so now we have a new yardstick
that's going to allow us to measure the expansion of the universe. Yeah, that was something I did in 1986.
So we've been waiting for a long time to be able to apply it. At the time
it was a very big thing in astronomy to measure the rate of expansion of the universe.
And I realized that we had another tool for measuring the Hubble Constant.
So that was what I wrote in my paper: Here's how to measure distances
and here's how to use it to measure the expansion of the universe. So
ever since then I've been waiting! Each of those individual
discoveries is a big deal. Putting them all together
just transforms that discovery. I think there's no doubt at this point
this is by far the most studied astronomical event ever in the history of
the universe. Well, that's very earth-centric, certainly in the history of our
human civilization. This binary neutron star event is going
to tell us things for the next ten years. This wonderful event. it’s sort of like in two years
we’re once again changing scientific history. (MUSIC) (MUSIC) (APPLAUSE) My call came just before Barry's.
Mine was at about 2:15 a.m. It was surprising how long they talked to
each of us. I was sound asleep and so the phone rang, I knew it was
the wee hours of the morning, I knew it had to be coming from Stockholm.
I struggled out of bed and took the call. I had thought, you know,
we've been expecting this. I had hoped it would go to the team.
It didn't. It went to us. But we had been expecting it.
So I thought, well, I'll be blasé, but in fact I was overwhelmed. So my call came after Kip's, but
enough after so that I had already -- we were warned this may happen, so we
were ready, not ready, but prepared. And so I had set the alarm for 2:40 a.m.
Knowing that 2:45 is when it was supposed to be live streamed.
I got up at 2:40 from the alarm. There had been no phone calls, (LAUGHTER) so I assumed they had
passed us over. Instead, I went to my
laptop to try to see, "Well, who did they
give it to or what?" And then my cell phone
started ringing, and whoever here can tell me
how they got my cell phone number that I give to nobody,
I don't know. But they called on my cell phone
and then was like Kip. My feelings at the time, I think
were a mixture between -- a complicated mixture between
being thrilled and being humbled. I told Samoan, “I'm going to go take
a shower,” which I did. And when I came out of the shower,
this guy that Caltech had posted was in our dining room. He had
two cell phones of his own, my cell phone,
my wife’s cell phone, and our house phone, and
his laptop, all open. And he was fielding all this stuff.
And they called all night long. About six in the morning, I think,
Reuters came and they took a whole bunch of pictures
on my front porch. And actually the pictures
that kind of quickly went in various newspapers
around the world were those Reuters pictures on our front porch. (MUSIC) Professor Weiss, Professor Barish,
Professor Thorne, you have been awarded the 2017
Nobel Prize for Physics for your decisive contributions to the
detector of the Laser Interferometer Gravitational-wave Observatory and for
the observation of gravitational waves. On behalf of the Royal Swedish
Academy of Sciences, it's my honor and my great pleasure to
convey to you our warmest congratulations. Ultimately this is about,
this really is about the curiosity, the ingenuity, the creativity of the best
that the human species has to offer. So that is the beautiful story that you have
enabled us to celebrate tonight and tomorrow. Let me just focus on Rai for a moment,
partly because he's the reason I'm here. Or partly because I want
to say I don't know a most humble human being
on the face of planet. But Rai one day needs to understand,
and Kip described that story beautifully yesterday, that without him
we wouldn't be here. You started with this. And yes,
it took someone smart like you, to smart someone perhaps
even smarter like you, like that guy, to convince him
that this is worth pursuing. And you assembled an amazing team,
including Barry and the rest of you to accomplish an amazing,
and achievable goal. So Rai one of these days,
you just have to accept, accept, that you
received a Nobel Prize. (APPLAUSE) I now ask you to step forward
to receive your Nobel Prizes from the hands of
His Majesty the King. (MUSIC) (APPLAUSE) In 2007, Barry was given an honorary PhD
degree by the University of Florida. He came and he gave this wonderful talk,
a very commanding presentation. And at the end of it, I have to remind you
at this time, 2007, the United States was deeply involved in the Iraq War, and
it wasn't going well for the United States. One of my senior colleagues, a very
distinguished physicist himself, a gentleman by the name of John Klauder,
comes up to me and says, "Dave, that guy, Barry Barish, if he were
leading the Iraq War, it would be over!" (APPLAUSE) The fact that it took that long,
that it took generations of scientists to get us where we are,
is of course a sign that it was not easy. The field has had supporters who kept
it going through those four decades. But of course not everybody was a supporter.
You heard a little bit of that in Barry's talk. And in Scotland we have a drinking
toast for such occasions, which I thought I would give to you.
"May those who love us, love us, and those that don't love us,
may God turn their hearts. And if he doesn't turn their hearts,
may he turn their ankles so we will know them
by their limping." (APPLAUSE) Kip, in his talk yesterday, was
inspiring about the future, about where we're going
after this discovery. So on behalf of the generations
of scientists to come, who are going to be able
to take advantage of that, thank you to the laureates for
all the work that they've done in getting us to the point that
we are tonight. Thank you. (APPLAUSE) In terms of Nobel Week, it's hard If you ask me
what's the most meaningful part of that? Sitting next to the Queen, which I did,
or walking with this beautiful princess, or all this, that's all great fun. It's hard
to say that anything is more meaningful than the actual ceremony, where you're
handed the medal and document, the certificate, by the king. But I
would say that another part of it actually got to me much more,
and was totally unanticipated. The ceremony, afterwards what people
don't realize is they come up and they take away your medal
and take away your certificate. Not for good, but because
they don't want you to lose it. Each of us have an appointment where
you went to the Nobel Foundation offices. And one of the things, you sit down,
and, you know, they give you the medal and this and that. And then a book opened
up to a page that had 2017 on the top. And you just signed it.
So there's nothing else but signing it, except that if you look back at
the page before it was 2016, the page before that 2015,
and so forth. So I could look back to see Feynman's
signature, or Bohr, or Shelly Glashow or anybody that I knew. To actually
feel that I'm in the same book as these guys had a huge impact
kind of emotionally on me. It was paging back, which
I did, that really got to me. We have a question from our
webcaster overflow room here. We have about 90,000 watching via
webcast, and it's actually a question that's been echoed throughout the Web:
Questions about what that means for us here on Earth. And will this
bring us further in the science of things like time travel
and high-speed traveling? Oh, Kip, this is tailor-made for you.
This is your question. I think it brings us a much
deeper understanding, by the combination of the
theory and the observation, a much deeper understanding of
how warped spacetime behaves when it is extremely warped.
I don't think it's going to bring us any closer to being able to do time travel.
I wish it would, but that's a different direction. LIGO's direction is really understanding the
wild dynamics of highly warped spacetime. When we look back on the era of the
Renaissance and we ask ourselves, "What did the humans of that era give
to us that's important to us today?" I think we would all agree it's great art,
great architecture, great music. Similarly, in a few hundred years,
when our descendants look back on this era and they ask themselves,
"What are the great things that came to us culturally from this era?"
I believe they will be an understanding of the fundamental laws
that control the universe and an understanding of what
those laws do in the universe, an exploration of the universe. LIGO is a big part of that.
