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00:00You had to admire people that would devote years and years and years to trying to do it with the likelihood being that they would fail.
00:08More than two decades ago, two teams decided to try what seemed impossible, to prove the existence of black holes.
00:19Both of these kind of converged at almost the same time, but coming about it in very different ways.
00:24We're crazy optimists in this business. You have to be.
00:27If you look at all the things that could go wrong, then why would you dedicate your career to it?
00:32One team called LIGO planned to use giant instruments called laser interferometers to detect tiny ripples in space-time called gravitational waves caused by the merger of two black holes.
00:47Albert Einstein thought that it will be impossible to ever detect them.
00:51We're looking for motions that are about a thousandth of the size of a proton inside the nucleus of an atom.
01:00The other team, called the Event Horizon Telescope, would try to capture an actual image of a black hole, a task comparable to seeing a tennis ball on the moon.
01:11And so you need a telescope the size of the entire Earth.
01:17But obviously, you know, we couldn't build a telescope the size of the Earth.
01:20But in radio astronomy, you can play this near magical trick where you take two telescopes separated by some distance, bring the data that they receive together to form a telescope as though you had one as large as the distance between these telescopes.
01:34Finding black holes, either by taking an image of one or by detecting them with gravitational waves, would be among the most difficult challenges in the history of science.
01:50I was sort of trembling in front of the challenge.
01:54It was hopeless because the technology would never be there.
01:57We staged experiments that went nowhere.
02:00We tried and we failed.
02:01And if they found what they were looking for, could they keep it secret until they were sure?
02:08Many people had a eureka moment.
02:10I was completely blown away by how clear-cut this signal was.
02:14And I had a moment of panic.
02:16We all kept the results secretly.
02:18Because I knew if that was right, we would be writing history.
02:22All I could do was figure out how we had gone wrong.
02:25How are we fooling ourselves?
02:28It's important to have to stop.
02:31And just listen to the universe.
02:45Black holes were born of theory.
02:48They might really exist.
02:50But there was no direct proof.
02:53Many felt that the idea itself must be fatally flawed.
02:56An extremely massive object will curve the space-time around it so much that anything that passes by will actually fall into that object and will not be able to escape.
03:13Even light wouldn't be able to escape.
03:16And that's basically a black hole.
03:18But is this real?
03:21Clearly, something like this would not occur in nature.
03:26No one felt that nature would be that crazy.
03:28These cosmic objects are more extraordinary than we could ever have dreamt up.
03:37At the center of a black hole, the laws of physics as we know today, they break down.
03:43There's no matter there.
03:44The structure that we see is a vacuum structure.
03:47It's like a tornado in space-time.
03:49In their purest form, the concept of black holes starts with Albert Einstein.
04:01For physicists, the great year for Einstein was 1905, when he solved several of the biggest problems in physics for the matter of months.
04:09And then he spent 10 years developing his theory of gravity, which is general relativity.
04:15What we see coming out of general relativity is that matter and energy has the ability to affect the space-time around it.
04:26Space-time is a mathematical concept that unites time with three dimensions of physical space,
04:32so that they are intimately woven together into what is called the fabric of space-time.
04:37If you send a light beam past, say, a star or a planet, the reason it bends is because it's trying to follow the straightest path possible
04:52in a geometry that is now curved, and thus, that is what gravity is.
04:58It's basically the geometry of space-time.
05:03Within weeks of Einstein publishing his revolutionary theory of gravity,
05:07people began trying to figure out what it all meant.
05:11One of the first was a German physicist called Carl Schwarzschild.
05:16Despite being in his 40s, Carl decided to volunteer to fight in the First World War,
05:21and he worked as an artilleryman.
05:23He was able to predict how space and time would look like around a point mass.
05:31And he realizes if you compact matter into a small enough volume,
05:35that there's this event horizon at what we can now call the Schwarzschild radius,
05:39where the speed of escape is larger than the speed of light,
05:43where even light cannot make it out.
05:45A one-way boundary where information and light can only go in but never can come out again.
05:50That's the moment when black holes really were born.
05:55Of course, completely crazy idea. This wouldn't exist.
05:59Neither man realized that it was anything more than a mathematical construct
06:03that they didn't really have to worry about because no one felt that nature would allow it to happen.
06:08Poor Carl Schwarzschild, he died very quickly after finding the solution
06:16due to an illness that he got in the trenches there.
06:20Throughout the 20th century, the theoretical study of black holes
06:24became vibrant and popular among scientists.
06:27They had theories for how they might form,
06:30and astronomers had even started to speculate
06:33about where they might lurk in the cosmos.
06:35So there are two varieties of black holes.
06:39There's a stellar variety, which are born during the death of stars,
06:43and they weigh a few or ten times what our sun does.
06:47Stellar-mass black holes are thought to have a Schwarzschild radius
06:51of around the size of a small modern city.
06:55Even though they have a mass of ten or twenty suns,
07:00they are tiny in comparison to the stars from which they were born.
07:03Supermassive black holes, however,
07:07would contain the combined mass of millions or even billions of suns.
07:12They could have a Schwarzschild radius the size of an entire solar system.
07:19Astronomers wondered if stellar black holes were hiding in all galaxies,
07:24and that supermassive black holes might be found at the heart of many.
07:27They even named the supermassive black hole that they suspected might lie at the heart of our galaxy,
07:34Sagittarius A-star.
07:38Are they out there?
07:39The theory predicted it, but are they really real?
07:43To try and answer that question,
07:45the team called LIGO would try to find the smaller black holes with gravitational waves,
07:50while the Event Horizon team would hunt the supermassive black holes
07:56using a type of astronomy that uses radio waves.
08:01If you have optical light, the wavelengths are tiny, tiny, tiny.
08:05But if you study radio emission, the wavelengths are actually big.
08:09And so you have a gigantic dish that can reflect radio waves.
08:14It was intense radio emissions coming from the center of galaxies
08:18that first made astronomers suspect that supermassive black holes must be the culprit.
08:25So we had to think a little bit about these emission mechanisms.
08:28What would cause is glow in radio waves.
08:31And so what can power something like that is gravitational accretion onto a supermassive black hole.
08:36It's the only way we know of to power something like this.
08:40In the 20th century, the idea of capturing an image of a black hole
08:45with these radio emissions was far beyond the realms of possibility.
08:49But some people did dare to dream.
08:53Many times in science, you wind up in a situation where somebody makes an initial discovery
08:58and it goes underappreciated.
09:00And this is the case with Jean-Pierre Lumenae.
09:03I mean, this was a real visionary.
09:04In 1979, he came with the first full simulation of what a black hole would look like
09:10if you were there, like if you could really see an infinite detail.
09:14To capture an image of a real black hole in the way that Jean-Pierre Lumenae imagined
09:19would require a radio telescope with a dish as big as the planet Earth
09:23and technologies that simply didn't exist yet.
09:27However, for the gravitational wave team, they had an even more fundamental problem to solve.
09:34Nobody even knew if gravitational waves were real at all.
09:40The theory behind them originated with Albert Einstein
09:43from around the same time that Carl Schwarzschild was formulating his ideas of black holes.
09:49In 1916, Einstein wrote a little paper, five pages long maybe.
09:55He looked at the equations of general relativity that he had developed
09:59and he noticed it had a great similarity, if you put it in a certain way,
10:04to the equations of electricity and magnetism.
10:07And since electricity and magnetism have waves,
10:10he conjectured that gravity must also have waves.
10:14By the 1930s, Einstein had written a further two papers
10:18on the subject of gravitational waves.
10:21According to Einstein, this phenomenon of gravitational waves
10:25is very interesting from a theoretical point of view,
10:28but any real effect on Earth will be so small
10:31that it will be very likely always impossible to ever detect them.
10:37They were never fully accepted during this whole period and beyond,
10:41even until his death.
10:44The great Albert Einstein died in 1955.
10:48Black holes and gravitational waves,
10:50ideas that were rooted in his theories,
10:52were far from being considered a reality.
10:55But in 1958, 50 of the world's greatest experts
10:59in general relativity had a meeting.
11:02So at this now-renowned conference,
11:04the question of whether gravitational waves
11:07really do exist and produce something
11:11that could be measured was raised.
11:13Richard Feynman was there.
11:15He said, if gravitational waves really exist,
11:18they have to be able to do something.
11:20They can't just exist.
11:21They have to be able to transfer energy.
11:23And so he made a, what we call a Gedanken experiment,
11:26just a thought experiment.
11:27And that was, if you have a bar
11:29and you put a couple rings on it and then a gravitational wave goes through the bar,
11:34it'll take the bar and it'll expand it and contract it and expand it and contract it
11:40at the frequency of the gravitational wave.
11:42As it expands, it, of course, pushes on the rings and they would move.
11:47But what's happening is that they're transferring energy friction to the ring.
11:51This clever thought experiment inspired one of the people at the meeting
11:57to actually build such a device.
12:00His name was Joseph Weber,
12:02and the machines he created are called Weber bars,
12:05the first ever gravitational wave detectors.
12:08It's accepted today that his bar detectors were not sensitive enough
12:14to be able to make any detections,
12:17but he played a very important role in sparking the rest of the world's interest
12:22into what a different type of detector might look like
12:26that could ultimately be more sensitive.
12:30So gravitational waves, if they exist,
12:33how do they manifest themselves?
12:34If I take just a place and a gravitational wave comes through,
12:41it distorts the space and time such that it stretches it in one direction
12:47and squashes it in the other direction.
12:49The easiest way to think about it is what happens
12:52when you go to the amusement park and you see these mirrors.
12:55You look in one and you get tall and thin.
12:57You go to the next one and you get short and fat.
13:00If you imagine that you're now a detector,
13:03it's basically going back and forth between those two mirrors.
13:07You're getting taller and shorter and fatter
13:09at the frequency of the gravitational wave.
13:12So maybe the gravitational wave is 60 hertz.
13:15So 60 times a second, you're going...
13:17And that's what we have to measure.
13:20So how are we going to measure that?
13:22So we had to find out a way to be able to detect here on Earth
13:28some very, very small perturbations.
13:30And it turned out that the most sensitive instrument
13:33that we could make and design
13:35is what is called a laser interferometer.
13:39So what does an interferometer do?
13:41I take a beam of light
13:42and I get to a place where there's a mirror
13:46that sends half the light in one direction
13:48and half the light in the perpendicular direction.
13:51If somewhere down the way I put a mirror,
13:54it'll bounce back.
13:56And if I've calibrated it so that the same length,
13:59they'll come back at exactly the same time.
14:01If I invert the signal from one to the other,
14:04they'll exactly cancel.
14:06I have a little photodetector.
14:08It sees nothing.
14:09Okay.
14:10But now imagine the gravitational wave
14:12went through the same thing.
14:14And 60 times a second,
14:15one arm's going to get a little longer than the other.
14:18The light will come back at a slightly different time.
14:21And the light will go 60 times a second,
14:24depending on how strong the gravitational wave was.
14:27And that's all we have.
14:29We have a detector that's measuring
14:30the length of these two arms.
14:33That's called interferometry.
14:35Two of the people who believe that interferometry
14:38might be the solution for finding gravitational waves
14:41and therefore for finding black holes
14:43were Rainer Weiss from MIT
14:46and Kip Thorne from Caltech.
14:50I started on the faculty at Caltech
14:52as a particle physicist.
14:54At the same time,
14:55Kip Thorne started as a general relativist
14:57and we were close friends.
14:59By the 1980s,
15:01several groups from around the world
15:02would start to consider building interferometers
15:05to search for gravitational waves.
15:06The British and Germans formed a collaboration.
15:10The Italians and French
15:12started a collaboration called Virgo.
15:15And in the U.S.,
15:17Rainer Weiss,
15:18Ron Drever,
15:19and Kip Thorne
15:20formed LIGO.
15:22But getting funding to build such a venture
15:24was not going to be easy.
15:26What was pointed out in the U.S. Congress
15:29about whether to appropriate funds
15:32was just how extraordinarily sensitive
15:34these detectors would have to be.
15:36You would need to be able to measure
15:39these mirrors moving at distances
15:42that were some 10,000 times smaller
15:45than the diameter of an atom.
15:48And when thinking about that
15:49in astronomical terms,
15:51that's maybe, say,
15:52the same as being able to measure
15:55the distance to the nearest star
15:56and being able to say definitively
15:59whether that distance has changed
16:01by the width of a human hair.
16:03And so these mind-boggling ideas
16:05were used as a way to cast doubt
16:08on the plausibility of such an experiment.
16:13In 1990,
16:14the National Science Foundation
16:16approved the construction of two detectors,
16:19Livingston, Louisiana,
16:21and Hanford, Washington State.
16:23But LIGO was going to need a lot of money
16:25and firm leadership
16:27if it was to stand a chance
16:29of finding stellar black holes
16:30with gravitational waves.
16:35The Event Horizon Telescope team
16:37that would try to take an image
16:39of a supermassive black hole
16:40would not officially form
16:42for many more years,
16:44though the ideas upon which it would be based
16:46were beginning to emerge.
16:49When I was in graduate school,
16:50I had the great fortune
16:51to work with Dr. Alan Rogers,
16:53who was one of the pioneers
16:54of radio astronomy.
16:55And he got me hooked
16:56on using interferometry
16:58to make the most detailed images of the sky
17:01that we could make at the time.
17:02And we started doing this
17:04with Sagittarius A star,
17:06which we thought was a supermassive black hole
17:08in the center of our Milky Way galaxy.
17:10So there's a technique out there
17:11that helps us with increasing the resolution
17:14that we can get from a telescope,
17:17which is not to use a single one,
17:19but to use pairs of telescopes
17:22and look at the distant object
17:25at the same time
17:27with these pairs of telescopes,
17:29record the incoming light.
17:31And because we time tag
17:32exactly when each signal arrived,
17:35we can, after the fact,
17:37combine these signals using supercomputers,
17:39just match them up
17:40and pretend we had the resolution
17:44of a telescope
17:45that's as big as the separation
17:47between the two.
17:49We call it very long baseline interferometry.
17:53And the key thing here
17:54is that we interfere the signals
17:58that we receive
17:59on different parts of the Earth.
18:00To use very long baseline interferometry
18:04or VLBI
18:06to actually capture an image
18:08of a supermassive black hole
18:10was going to require
18:11a radical leap forward
18:13in our understanding
18:14of how matter
18:15spins around a black hole
18:17that is feeding
18:18the so-called accretion disk.
18:21I think any revolution
18:22requires a group of people
18:24sorting out the ideas
18:26that they have,
18:26figuring out what's the best way
18:28to move forward.
18:28I met DeVetrios
18:30when we were both at Harvard.
18:33In fact,
18:33our first paper together
18:34is on Sagittarius A star,
18:37the emission from it,
18:38and whether the accretion flow
18:41around the black hole
18:42would allow us
18:43to see down to the horizon.
18:45It was a time
18:46where we had just started
18:47thinking differently
18:48about how do black holes
18:50accumulate matter
18:52from their surroundings.
18:53For about 20, 30 years,
18:54there was a paradigm,
18:55but then it became obvious
18:57sometime in the 90s
18:58that that paradigm
18:59was not right.
19:01So it was that small group
19:02that started building
19:03a new paradigm.
19:05We were doing this
19:06theoretically.
19:07You know,
19:08we were thinking about
19:09where does this radio emission
19:10come from in black holes?
19:12Some people proposed
19:13that this would come
19:14from the matter
19:15that shoots out
19:16from the plasma jets,
19:17and other colleagues
19:18were calculating
19:19that the radio emission
19:20would come from the matter
19:21falling into the black hole.
19:22We had group meetings
19:24that lasted eight hours.
19:26We just had coffee,
19:26we just had a whiteboard,
19:28and we were trying out ideas.
19:29And most of them were wrong,
19:31most of them failed.
19:32But a few of them
19:33turned out to be really important.
19:35One of those questions
19:36that we wanted to ask
19:37is what would the black hole
19:38look like
19:39if I were to take a picture?
19:41Will it be a big,
19:42fuzzy fluff of cloud,
19:44or will it be something
19:45really small,
19:46as small as the event
19:47horizon of the black hole?
19:48So we spent about 10 years
19:50learning how to tweak the theory
19:52and make predictions
19:54of black holes
19:55that were not the same
19:56as the ones
19:57that Albert Einstein predicted.
19:59And lo and behold,
20:01we always saw
20:02this dark shadow
20:04in the very center.
20:07Irrespectively of how
20:08the matter was rotating,
20:10whether it was falling in,
20:11whether it was flowing out,
20:12whether the black hole
20:13was rotating,
20:14as long as the mass
20:15was known as the black hole,
20:16the shadow had to be there.
20:18So in year 2000,
20:20I realized that
20:21at certain wavelengths,
20:23the entire accretion flow
20:25is actually transparent
20:27and allows us to see
20:28all the way down
20:29to the horizon of the black hole,
20:31which is what we are after,
20:32that shadow.
20:33How would that look like?
20:35Could we actually see that?
20:37It turns out that
20:37the answer depended
20:38on how did I take the picture,
20:40what wavelengths of light
20:41did I use?
20:42This new multinational community
20:47of radio astronomers
20:48and theorists realized
20:50that the key
20:51was to push
20:52very long baseline interferometry
20:53to see higher frequencies of light.
20:55The higher frequency you observe,
20:58the finer your angular resolution.
21:00Your pictures get much crisper
21:01and you can see the details
21:03that you want to see.
21:04But the second thing is
21:05that as you move higher in frequency,
21:08you can see more deeply
21:09into all the hot gas.
21:11So you really want to see
21:12all the way to the event horizon.
21:14You want to get sharper images
21:15and that pushed us
21:16to higher frequencies.
21:17The target that everyone
21:19was focusing on
21:20was the suspected
21:21supermassive black hole
21:22at the center of our galaxy,
21:25Sagittarius A-star.
21:27I was convinced
21:28we would be able
21:29to see the black hole
21:31at the center of our Milky Way
21:32with a global telescope array.
21:34But that required
21:35a lot of money,
21:37new telescopes,
21:38new receivers,
21:39and it required
21:40a big community
21:41to work together.
21:47There's a transition
21:48that many areas of science
21:50go through
21:50in terms of moving
21:52from things
21:52in the laboratory,
21:53taking those ideas
21:54and concepts
21:55and scaling them up
21:56to turn those
21:58into a large-scale project.
22:00It's a skill in itself.
22:02Barry Barish
22:02had been working
22:03in particle physics
22:04at the superconducting
22:06supercollider in Texas.
22:08The U.S. Congress
22:09canceled the supercollider
22:11at a time
22:12when LIGO needed somebody
22:14that was capable
22:15of taking it
22:16to get both the funding
22:18that was needed
22:19and be able
22:20to put it together
22:21in a way
22:21that would make it work.
22:23In 1994,
22:25the National Science Foundation
22:26made Barish
22:27the laboratory director
22:29of LIGO.
22:30About six months later,
22:31went to the National Science Board
22:33that oversees
22:34the National Science Foundation
22:36and convinced them
22:37that they funded this.
22:39I think the real hero
22:41is not me.
22:42It's the NSF.
22:43For me,
22:44the big issue
22:44was to get a strong enough team.
22:47As good as these two institutions are,
22:49Caltech and MIT,
22:50for our problem
22:51as hard as gravitational waves,
22:52we needed to tap
22:53the best people in the world.
22:55The underlying technologies
22:57that are relevant
22:58for gravitational wave detection
23:00were being developed
23:01in different places.
23:02In 1997,
23:04Barish established
23:05the LIGO Scientific Collaboration,
23:08which merged
23:08several international groups
23:10into LIGO.
23:11This meant
23:12there were now
23:13two major multinational groups
23:15vying to build detectors,
23:17LIGO and VIRGO.
23:20The group that would become
23:21the Event Horizon Telescope
23:23were also making progress.
23:27So we all started to work together
23:29at three-millimeter wavelength.
23:30And then we realized
23:31that to push it even further,
23:33we had to go to
23:33one-millimeter wavelength.
23:34And that's when we began
23:35this real race,
23:37a competitive,
23:38but also a collegial race.
23:40Could we push this technique
23:42to its real limits?
23:44And that was a great time.
23:46And then we ran
23:47into this roadblock.
23:50For many years,
23:51we were stymied.
23:53We were just stuck
23:53because we didn't have
23:54the sensitivity we needed
23:56to make these observations
23:57at high frequencies.
23:58As soon as you go
23:59to high frequencies,
24:00everything becomes harder.
24:01The atmosphere reduces
24:03the signal coming
24:04from black holes.
24:06The superconducting cameras
24:08that we mount
24:09on each of our telescopes
24:10to receive the radio waves
24:12from the black hole,
24:13they become more noisy.
24:14So everything is working
24:15against you.
24:16The one thing that we had,
24:18our secret weapon,
24:19was that we could increase
24:20the bandwidth.
24:23Starting in around 2000
24:24and going until about 2006,
24:26there was this explosion
24:28in capabilities
24:29that happened
24:30because we started building
24:32our instruments
24:33out of commercial electronics.
24:34Imagine that.
24:36Up until that point,
24:37we had been developing
24:39specialized instrumentation
24:41that took a decade
24:42to design and manufacture
24:44and get into the field
24:45because it was so
24:46exquisitely specialized.
24:48Graphics processing units,
24:50or GPUs,
24:51are specialized computer chips
24:53that are used primarily
24:54for video graphics.
24:57We weren't pushing
24:58the development of GPUs.
25:00In fact,
25:00the gaming industry was.
25:02But we thought,
25:04hey,
25:04we can solve
25:05ice-sized equations
25:06on these things
25:07and we can do it
25:08much faster
25:09than with traditional CPU.
25:11The same was true
25:13for data storage.
25:14Consumer hard drives
25:15were becoming
25:16ever faster
25:17and greater in capacity.
25:19All of a sudden,
25:20we could go to the store,
25:21buy components,
25:22hook them together,
25:23and we could make something
25:24that was 10 times
25:26more capable,
25:2710 times lower cost,
25:28and we could design it
25:2910 times faster.
25:30It was nothing short
25:32of a mirror.
25:37The LIGO detectors
25:39had to be the most
25:40sensitive scientific
25:41instruments in the world.
25:43And it's all because
25:44our planet
25:45is such a noisy place.
25:48Much of the good work
25:49happens at night.
25:50And that's simply because
25:52the environment around you
25:53is quieter at night.
25:55There are fewer cars
25:56driving on the road,
25:57hitting bumps
25:58and causing the ground
25:59to shake people
26:00felling trees
26:01that are falling down
26:02in the forest.
26:03The operation of heavy
26:04machinery nearby
26:05is also lower at night.
26:08There's also natural effects.
26:10Of course, earthquakes
26:11are an obvious consideration
26:13that might jump
26:14to many people's minds.
26:15Believe it or not,
26:16even if you're in the center
26:17of a continent,
26:18there is a peak
26:19of motion
26:20that occurs
26:21at very low frequency
26:22due to waves
26:23beating on the ocean shore.
26:26The reason that
26:28all of these sorts
26:28of things matter
26:29is because ultimately
26:31these mirrors
26:32that we're trying
26:33to detect
26:34very small motions of
26:36are connected
26:36to the ground.
26:38The earth,
26:38the ground,
26:39is shaking
26:40all the time
26:41by about a millionth
26:42of a meter,
26:43which is a million
26:44of a millionth
26:45times more
26:46than what we're
26:46trying to measure.
26:47So this is one reason
26:49that our system
26:50cannot just sit
26:51on the ground
26:52but our mirrors
26:53are the most
26:54quiet place
26:55on earth.
26:57The beam splitter
26:57itself is a mirror,
26:59a big piece of glass
26:59suspended on wires.
27:01That has to be
27:02isolated
27:03from external disturbances
27:05so it's housed
27:06inside a vacuum tank.
27:07That vacuum tank
27:08is inside a big building.
27:12Out from that building
27:13go two arms.
27:15Inside that arch
27:16there's a vacuum pipe.
27:18Inside that
27:19travel the laser
27:20tribunes
27:20that travel
27:21the length
27:21of these
27:22four kilometer arms.
27:23The ends
27:23of the arms
27:24inside those buildings
27:25there are vacuum tanks.
27:28Inside those tanks
27:29are some isolation systems
27:31that isolate
27:33from ground vibrations
27:34mirrors that are
27:35suspended
27:35in the initial incarnation
27:37of LIGO
27:38on metal wires.
27:41But it's not
27:42just vibrations
27:43and noise
27:44that LIGO
27:44has to fight against
27:45but barely imaginable
27:47quantum effects.
27:49To measure precisely
27:50how the two waves
27:51get together
27:52you have to measure
27:53how many photons
27:54hit your detector.
27:55But since the number
27:56of photons
27:57is what we call
27:58a quantum variable
27:59there's an intrinsic
28:00uncertainty there.
28:01We cannot do better
28:02than what the
28:03Eisenberg uncertainty
28:04principle dictate.
28:06That's one reason
28:06we need very powerful lasers.
28:08As we increase
28:09the laser power
28:10the force exerted
28:13by the light
28:13on the mirrors
28:14also increases
28:15proportionally.
28:17So that becomes
28:17one of the big challenges
28:18of increasing
28:19the laser power.
28:21Every time a photon
28:22bounces off
28:23our suspended mirror
28:24it transfers
28:25some momentum
28:27to the mirror.
28:27It gives it a kick.
28:28If it were to strike it
28:30off center
28:31it's going to actually
28:32create a torque.
28:33The light causes
28:34the mirrors to twist.
28:35In an ideal situation
28:37you would have
28:37the light striking
28:38the center of the mirror.
28:41So to be able
28:42to understand more
28:43about black holes
28:44and big stuff
28:45out there in the universe
28:46we need to understand
28:47very well
28:47the physics
28:48of the quantum mechanics
28:50and the thermal motion
28:51of the atom
28:51which is very small scale physics.
28:55In 2006
28:57we fielded
28:58these new
28:58electronic systems
29:00for the first time
29:00and we took them
29:01to two sites
29:02one in Arizona
29:03Mount Graham
29:03and one to
29:04Mauna Kea
29:05in Hawaii.
29:06We set up
29:07this experiment
29:08but we were really
29:09flying a bit
29:09by the seat
29:10of our pants.
29:11So back
29:12at the core later
29:13we played
29:14these data streams
29:15from Hawaii
29:15and Arizona
29:16back again
29:17and again
29:17and again
29:18and we searched
29:19for months
29:20and it was
29:20a heartbreaker.
29:22After months
29:22we threw in the towel
29:24and we realized
29:24that we were just
29:25not going to be able
29:26to detect
29:26Sagittarius A star.
29:29Later
29:30we found out
29:30why
29:31a small little
29:32chip of metal
29:33had fallen
29:34into the heart
29:35of the superconducting junction
29:37in the receiver
29:39of the Caltech
29:40submillimeter observatory.
29:44We were able
29:44to go back
29:45the next year
29:45adding a new site
29:46in California
29:47and this time
29:49we were successful
29:50we got the detections
29:52and that showed us
29:53immediately
29:53that we were seeing
29:54horizon scale structure.
29:56That's the moment
29:57we knew
29:57that we could make
29:58an image
29:58to a black hole.
30:02The LIGO team
30:04were sure
30:04they had detectors
30:05that were working well
30:06but if black holes
30:08were spiraling
30:09into one another
30:10somewhere in the universe
30:11they were not hearing it.
30:14You don't know
30:15that you don't see something
30:16until you look
30:17for a while
30:17and so it would run
30:19for six months
30:21or a year
30:22and wouldn't see
30:24any events.
30:26We'd turn off
30:27lick our wounds
30:28put in some improvements
30:29and then run again.
30:31But I think that was also
30:32maybe part of the excitement
30:33so there was years
30:34and years and years
30:35of continually improving
30:36the detectors
30:37collecting data
30:38improving them
30:38collecting data
30:39and no detection
30:40no detection
30:41no detection.
30:42There were times
30:43where myself
30:45or the community
30:45thought that maybe
30:46we got ourselves
30:48into something
30:48to be.
30:50The initial version
30:50of LIGO
30:51wasn't good enough
30:52to see gravitational waves
30:53it turns out.
30:56In 2010
30:57the detectors
30:58were scheduled
30:58to shut down
30:59in preparation
31:00for a big upgrade
31:01called
31:02Advanced LIGO.
31:04The team
31:04trying to make
31:05an image
31:05of a black hole
31:06realized
31:07that the friendly
31:08competition
31:08between several
31:09European and US
31:11institutions
31:11wasn't going
31:12to be enough.
31:14We would need
31:15many more dishes.
31:16We would need
31:17the European dishes
31:17we would need
31:18the American dishes.
31:19So it was clear
31:20at some point
31:21those different efforts
31:22had to come together
31:23and merge
31:24into a global
31:25collaboration.
31:27And so there was
31:28a meeting in 2009
31:29in California
31:30and I was sitting there
31:32at a coffee break
31:33together with
31:33Chef Dolman
31:34and was saying
31:34if we want to get
31:36this funded later
31:37we can't just keep
31:38talking about
31:39sub-millimeter
31:39VLBI array
31:40blah blah blah
31:41nobody will understand
31:42what it is
31:42we have to give
31:43it a flashy name.
31:44What about
31:45if we call it
31:46Event Horizon Array
31:48or something
31:49like this
31:49and in the end
31:50we came down
31:51to Event Horizon
31:52Telescope
31:52and that's how
31:53it started.
31:55The Event Horizon
31:56Telescope
31:57was finally
31:58and officially
31:59born.
32:01Meanwhile
32:01LIGO
32:02was in the middle
32:03of its upgrade
32:04from initial LIGO
32:05to advanced.
32:07We wanted to build
32:08a very sensitive
32:08instrument
32:09and that meant
32:10that we had
32:12to take
32:12some risks
32:13if you want.
32:14Much of the effort
32:15that went into
32:16the advanced
32:17LIGO upgrade
32:17involved the mirrors
32:19and how they
32:20were isolated
32:21from the outside world.
32:23So instead
32:24of suspending
32:24these mirrors
32:25on metal wires
32:26we were actually
32:27suspending them
32:28on glass fibers
32:30fused silica fibers.
32:34Those fibers
32:35they're very strong
32:35if you pull them
32:36but if a grain
32:37of dust
32:38hit them
32:39they shatter.
32:40Perhaps
32:41the greatest
32:41secret weapon
32:42that the LIGO
32:43team employed
32:44to isolate
32:45their detectors
32:45from unwanted
32:46vibrations
32:47was the same
32:48technology found
32:49in noise cancellation
32:51headphones.
32:53You put on
32:54these earphones
32:54on an airplane
32:55and the roar
32:56of the engines
32:57goes away
32:57and you still
33:00hear the stewardess
33:00ask you
33:01do you want coffee?
33:03So what it does
33:04is measure
33:04the ambient noise
33:05of the engines
33:06and cancel it
33:08but the stewardess
33:10talking to you
33:10is not ambient
33:11and it's a signal
33:12and so you hear
33:13that fine.
33:14So the idea
33:14was to bury
33:15inside of
33:16these shock absorbers
33:17little seismic
33:18sensors
33:19that measured
33:20any residual motion
33:21of the earth
33:22and then we just
33:23push back
33:24against it
33:25you know
33:25make little
33:26actuators
33:26that push
33:27and cancel
33:27the residual motion
33:28that's there
33:29after the shock absorbers
33:30and that gained
33:32us a factor
33:33of 10
33:33in sensitivity.
33:37The Event Horizon
33:39Telescope Group
33:40had begun
33:40to consider
33:41trying to image
33:42another supermassive
33:43black hole
33:43as well as
33:44Sagittarius A star.
33:47There was another
33:48black hole
33:49out there
33:50which was
33:50a thousand times
33:51further away
33:52but also
33:52a thousand times
33:53more massive.
33:55M87
33:56is a galaxy
33:57about 53 million
33:58light years
33:59from earth
33:59and just like
34:01the Milky Way
34:01we suspect
34:02it has a supermassive
34:04black hole
34:04at its center
34:05only one
34:07that is much bigger.
34:09M87 is so massive
34:10that it doesn't change
34:11during the course
34:12of an evening
34:13whereas Sagittarius A star
34:14is speedier
34:15and during the course
34:17of a night
34:17it changes
34:18its appearance.
34:20The advanced
34:21LIGO detectors
34:22were now successfully
34:24upgraded
34:24and showing
34:25much higher sensitivity
34:26than anything
34:27achieved before.
34:28When we start
34:30a data run
34:31each year
34:32when we do this
34:32there's a little
34:33period of time
34:34when people
34:35who are expert
34:36on particular things
34:37can still decide
34:39to make some
34:39changes of settings
34:40so we call it
34:41an engineering run
34:42it happened
34:42during that period.
34:45You can imagine
34:46that I can remember
34:46very well
34:47that day
34:48so it was a Monday
34:49and I remember that
34:50because that was
34:51the day after
34:52I ran my first marathon
34:53so I was thinking
34:54that that was enough
34:55excitement for a while
34:56right?
34:57I remember
34:58quite vividly
34:59in my office
34:59in Glasgow
35:00when our colleague
35:01suddenly said
35:01you do know
35:02the signal
35:02had just arrived
35:03and we were like
35:04no.
35:05My colleague
35:06came to tell me
35:07that it seems
35:08there's been a detection
35:09I just brushed
35:10this comment off
35:12to me it seemed
35:13oh we're not even
35:14in the observation
35:15run yet
35:16it's too early
35:17for this to actually
35:18happen.
35:21When that event
35:22happened
35:23it happened
35:24seven milliseconds
35:25earlier
35:25in Louisiana
35:27than in
35:27Hanford
35:28and my first
35:32thought was
35:32this can't be real
35:33this is too good
35:34to be real
35:35and you have to
35:37imagine
35:37for people
35:38who've spent
35:38decades
35:39measuring noise
35:40and being very good
35:42at measuring noise
35:43to have a signal
35:45arrive
35:46and it be large
35:47it really did
35:47take people
35:48by surprise.
35:49the detection
35:51made on the 14th
35:52of September
35:532015
35:54was calculated
35:55to have been
35:56created by the
35:57merging of two
35:58stellar mass
35:58black holes
35:591.3 billion
36:01light years
36:02from earth.
36:02we were expecting
36:06to have to fight
36:07our way
36:08through a lot
36:09of justification
36:09to convince people
36:11that we really
36:12had seen
36:12gravitational waves
36:13but that was
36:14exactly what
36:15you would expect
36:15out of a textbook
36:16so the first thing
36:19I thought is
36:20this is not real
36:21somebody did this
36:22because at the time
36:23we had a program
36:24which was called
36:25blind injections
36:25to test if you
36:27were actually able
36:27to detect
36:28gravitational waves
36:28some people
36:29without telling
36:30anybody
36:31would add
36:32on purpose
36:32fake signals
36:34so all I could
36:35think is that
36:36great
36:36this is an
36:37artificial signal
36:38but we got
36:39words from
36:40whoever was in
36:41charge
36:41of this
36:42blind injection
36:42saying no
36:43we didn't have
36:44time to set up
36:45this whole system
36:45sorry we're late
36:46so this is not
36:47a blind injection
36:48but that was not
36:51the end of the
36:52story
36:52that was the
36:53beginning of
36:53maybe six months
36:54of very hard work
36:56to try and prove
36:58that we didn't do
36:59anything wrong
37:00because you don't
37:03want to cry wolves
37:03the first time
37:04you detect the
37:06gravitational wave
37:07because that had
37:07happened in the
37:08history in the past
37:09so we don't want
37:10to do that
37:10because then you
37:11lose credibility
37:11of course
37:12I think for many
37:15people justifiably
37:16after many years
37:17they had a eureka
37:19moment and I had
37:21a moment of panic
37:22all I could do
37:24is figure out
37:24how we had
37:26gone wrong
37:26there then
37:29followed a frantic
37:30and intensely
37:31busy period
37:32of forensically
37:33analyzing whether
37:34they believed
37:34their own data
37:35after a month
37:38we met
37:38and we decided
37:39it was real
37:39and I thought
37:40it was real
37:41that moment
37:42of looking at
37:43the data
37:43really kind
37:44of made me
37:45jump
37:45we kept it
37:46quiet
37:47even though
37:47we have a
37:47thousand people
37:48we had one
37:49office with
37:50several students
37:50in it
37:51and all of them
37:52apart from one
37:53were in the
37:53LIGO collaboration
37:54so this poor
37:56one student
37:56for about six
37:58months
37:58every time he
37:59walked into the
37:59office
38:00everybody stopped
38:00talking
38:01and he just
38:02must have been
38:02wondering
38:03what he had
38:04done wrong
38:05was it him
38:05was it me
38:06Barry and his
38:09team agreed
38:10that they would
38:10publish their
38:11results in the
38:12journal
38:12physical review
38:13letters
38:13before Christmas
38:142015
38:15we had our
38:17final meeting
38:18to decide
38:19that it was
38:19ready to go
38:20but it hung up
38:21in that meeting
38:21we couldn't
38:22agree to
38:22publish it
38:23so why
38:24basically we
38:26argued over
38:26adjectives
38:27is the title
38:28discovery of
38:29gravitational waves
38:30is the title
38:31evidence for
38:32anyway we hung
38:33up on this
38:34and so it took
38:35us another
38:35I don't know
38:36week
38:36and then we
38:37called physical
38:38review letters
38:38and they said
38:41oops it's too
38:42late
38:42it's too close
38:43to Christmas
38:44so we said
38:45okay then we
38:45are not giving
38:46it to you
38:46until after
38:47Christmas vacation
38:48I tell this
38:49story because
38:50on December
38:5026th
38:51Boxing Day
38:52we saw our
38:53second event
38:54only three and a
38:56half months
38:57after the first
38:57one another
38:58black hole
38:59merger has been
39:00detected
39:01and even though
39:02I had gone
39:03through all this
39:04intense fall
39:05and was absolutely
39:06I thought
39:07convinced
39:08seeing the
39:09second event
39:10was a sigh
39:11of relief
39:11in me
39:12I didn't
39:13anticipate it
39:14but there's
39:15something about
39:16confirmation
39:16no matter how
39:17much you look
39:18at something
39:18and believe
39:19what you've
39:19done
39:19in February
39:222016
39:23LIGO
39:24in collaboration
39:25with Virgo
39:26told the world
39:27ladies and
39:28gentlemen
39:28we have
39:32detected
39:32gravitational
39:34waves
39:34we did it
39:36the discovery
39:43of gravitational
39:44waves
39:44probably the
39:45greatest
39:45discovery
39:46since we
39:47first learned
39:47that the
39:47universe was
39:48expanding
39:49not only do we
39:50now have to
39:50believe in black
39:51holes
39:51we have to
39:52believe that
39:52they collide
39:53too
39:53seeing the
39:54first detection
39:55of gravitational
39:56waves
39:56while we were
39:57still in the
39:58thick of doing
39:58the event horizon
39:59telescope observations
40:00was awesome
40:00was remarkable
40:01there's always
40:02been a little
40:03bit of friendly
40:03competition with
40:04the LIGO team
40:06although I would
40:07say that I think
40:08people didn't
40:08appreciate how
40:09close we came
40:10we accreted new
40:13partners from
40:14Europe
40:14new partners
40:15even from Asia
40:16and we all began
40:17to work together
40:18and finally in
40:202017
40:20we were ready
40:21but a telescope
40:23that covers the
40:24whole planet
40:25has some uniquely
40:26frustrating problems
40:28with normal
40:29astronomy
40:29you need good
40:30weather
40:30at just the
40:31telescope
40:31that you're
40:32observing with
40:32but for very
40:33long baseline
40:33interferometry
40:34you need weather
40:35to be good
40:36all over the
40:36globe
40:37and I was
40:38going up
40:39to the 30
40:41meter dish
40:41at IRAM
40:42but it was
40:43perfect weather
40:44and it was
40:46perfect weather
40:47all around the
40:48world
40:48at the other
40:49places
40:49and I said
40:50this can't be
40:51we have good
40:51weather here
40:52and I was just
40:53nervously looking
40:54at the hard drives
40:55and the equipment
40:56but all the
40:56equipment was working
40:57at each of
41:01these telescopes
41:01we have what's
41:02called a hydrogen
41:03maser
41:03that time tags
41:05the data
41:05it's digitized
41:06stored on a
41:07hard disk drive
41:08and they're sent
41:08by trucks
41:09by planes
41:10to a central
41:11facility where
41:12they're played
41:12back
41:12the first data
41:14was coming back
41:14to haystack
41:15and they were
41:15doing the first
41:16correlations
41:17and the first
41:18success
41:18and messages
41:19came
41:19these two
41:20telescopes
41:20work together
41:21these two
41:21telescopes
41:21work together
41:22and after a
41:23few weeks
41:24and months
41:25we knew
41:25it probably
41:26worked
41:27we didn't know
41:27what it was
41:28showing us
41:29that moment
41:31of joy
41:32and epiphany
41:33came when
41:34we saw
41:35the data
41:36making this
41:36ringing pattern
41:38and it was
41:39a curve
41:39of data
41:40going down
41:41going up
41:42again
41:42just looking
41:43at it
41:43we thought
41:44we have a
41:45ring
41:45if that's
41:46true
41:46we're really
41:47lucky
41:48oh my god
41:49this works
41:49once
41:51once all
41:52the data
41:52from all
41:53the radio
41:53telescopes
41:54are collected
41:54the process
41:55of creating
41:56an image
41:57can begin
41:57and so
41:59what they do
42:00is they take
42:00the light
42:01that has been
42:02frozen at
42:02every one
42:03of these
42:03telescope sites
42:04and they
42:04play them
42:04back together
42:05and they
42:06average it
42:06and average
42:07it down
42:07so much
42:08because there's
42:08only a tiny
42:09little signal
42:10riding on
42:11a huge amount
42:11of noise
42:12you get a
42:12little nugget
42:13of information
42:14that's passed
42:14on to the
42:15imaging algorithms
42:15and that
42:16little nugget
42:16is what we
42:17use to make
42:18the picture
42:18but the
42:20problem is
42:21we're not
42:21collecting light
42:22from everywhere
42:22there's a lot
42:23of holes now
42:24and so
42:25the big
42:25challenge
42:25was taking
42:26that sparse
42:27and noisy
42:28data
42:28and using
42:30it to recover
42:31an image
42:31it's very
42:32similar to
42:33if you're
42:33listening to
42:34a song
42:34being played
42:35on a piano
42:35that has
42:36a lot
42:36of broken
42:36keys
42:37and even
42:37though a lot
42:38of the keys
42:38are broken
42:39a lot
42:39of times
42:40you can
42:40still try
42:40to make
42:41out what
42:41the song
42:41is
42:42the problem
42:43is what
42:43we call
42:43ill post
42:44there are
42:44many different
42:45kinds of
42:45images
42:46that correspond
42:47to the same
42:47data
42:48that we
42:48measure
42:48and so
42:49we wanted
42:49to put
42:49all that
42:50aside
42:50and just
42:51say
42:51ignoring all
42:52of our
42:52ideas
42:53of general
42:53relativity
42:54and all
42:54the ideas
42:55that we
42:55believe right
42:56now
42:56as far as
42:57what we think
42:58a black hole
42:58should look
42:59like
42:59and just
43:00see what
43:00is the data
43:01telling us
43:01does the data
43:02say that there
43:03should be a ring
43:03how about a disc
43:04how about
43:05you know
43:05an elephant
43:06it would be very
43:11easy within a
43:12collaboration of
43:13this size
43:14to have three
43:14different imaging
43:15techniques for
43:16example
43:16and to decide
43:17that one of
43:18them was the
43:18way to go
43:19but that would
43:20have created
43:20a problem
43:21because proponents
43:22of the other
43:22two methods
43:23which might be
43:23also very very
43:24good would have
43:25felt left out
43:26so we adopted
43:27this method
43:28of using all
43:30of these
43:30different techniques
43:31as checks
43:32and balances
43:32we allowed
43:34everyone to
43:34proceed with
43:35their particular
43:36algorithm
43:37their particular
43:38imaging method
43:39and we worked
43:40in isolation
43:41with our teams
43:42for seven weeks
43:43trying to make
43:44what we thought
43:45was the best
43:45image from the
43:46data
43:46and after those
43:48seven weeks
43:48we actually all
43:49gathered together
43:50in Cambridge
43:50Massachusetts
43:51and we revealed
43:52those images
43:53to each other
43:53but no matter
43:54what even though
43:55the different teams
43:56resulted in
43:57slightly different
43:57images
43:58the same
43:59underlying structure
44:00was there
44:01this ring
44:01of roughly
44:0240 micro arcseconds
44:03that was brighter
44:03on the bottom
44:04than the top
44:04but even at that
44:06point we weren't
44:07sure
44:08and so what we did
44:09is then we spent
44:10the next couple months
44:11essentially trying
44:11to break our images
44:12so we took the data
44:15and we trained
44:16our methods
44:16we figured out
44:17what were the
44:18hyperparameters
44:18what were the knob
44:19settings of our
44:20methods
44:20to recover things
44:22like disks instead
44:23so we generate
44:24a disk on the sky
44:25as if the event
44:26horizon telescope
44:26were seeing a disk
44:27with no hole
44:28in the center
44:28and then we'd
44:30transfer those
44:30exact parameters
44:31onto the real
44:32M87 black hole
44:33data
44:33and although
44:34we had tried
44:35our hardest
44:35to find parameters
44:36that would recover
44:37a disk
44:37with no hole
44:38in the center
44:38we saw that
44:39when we used
44:40those parameters
44:41on the real
44:41black hole data
44:42the data forced
44:44us to put a hole
44:45there
44:45although each
44:46individual image
44:47looks slightly
44:47different
44:48that ring structure
44:49is consistent
44:49across all of them
44:50that's when we knew
44:52that we could then
44:53come with a real
44:54scientific publication
44:55and a real
44:56press release
44:57to announce
44:58that we'd seen
44:59the first image
44:59of a black hole
45:00the image
45:04had to be released
45:05all around the world
45:06at the right moment
45:08was all timed
45:09to the second
45:10and for that
45:11professor Heino Falke
45:13is here
45:14still have to
45:15we all knew
45:19in July of 2018
45:20what we had
45:21Dr. Shep Doleman
45:23EHT's director
45:24and from that time
45:26until April
45:27of the following year
45:28nobody breathed
45:29a word of it
45:30we all kept
45:31the results secret
45:32now I have to
45:33fill the time
45:34actually until we
45:35allow it to actually
45:35you know
45:36start the unveiling
45:37despite all the
45:39struggle
45:39all the exhaustion
45:41we kept it
45:42under the lid
45:43until we were able
45:44to really release it
45:45and even up to
45:47the day we made
45:48the announcement
45:48everyone thought
45:49that we were going
45:50to say something
45:51about Sagittarius A star
45:52when in fact
45:53we had imaged M87
45:54in April of 2017
45:57all the dishes
45:58in the Event Horizon
45:59Telescope swiveled
46:00turned and stared
46:02at a galaxy
46:0255 million light years
46:04away
46:04it's called
46:05Messier 87
46:06or M87
46:07and there's a
46:09supermassive black hole
46:10at its core
46:11and we are delighted
46:12to be able
46:13to report to you
46:14today
46:14that we have seen
46:16what we thought
46:17was unseeable
46:18we have seen
46:20and taken a picture
46:21of a black hole
46:23here it is
46:25this is
46:28the first ever image
46:29of a black hole
46:30we all expected
46:39a lot of good reaction
46:41from the public
46:41but I think
46:42we're all extremely
46:43surprised
46:44by how quickly
46:46it became
46:46a classic
46:47it became
46:48the iconic image
46:49of a black hole
46:49and this is the
46:52strongest evidence
46:53that we have to date
46:54for the existence
46:55of black holes
46:56when I saw that picture
46:59I just thought
47:00that that was
47:01the most beautiful
47:02photo I've ever seen
47:03I picked up
47:08the New York Times
47:08as I do every morning
47:09but there was
47:10this beautiful picture
47:11of a black hole
47:12but I just
47:15didn't
47:16see it coming
47:17and then suddenly
47:19there were these pictures
47:20and I was like
47:20nobody had ever seen
47:31a black hole
47:31at some point
47:33seeing is believing
47:34some people think
47:40of black holes
47:40as being frightening
47:41and confusing objects
47:43but I don't
47:44I'm in love with them
47:45I have no problem
47:47cozying up
47:48to black holes
47:49for the simple reason
47:51that they are
47:52the one way
47:53we'll be able
47:53to understand
47:54how gravity
47:54and quantum mechanics
47:56ultimately
47:58have to join forces
48:00physics is a terribly
48:02embarrassing field
48:03we've got two wonderful theories
48:05and never the twain shall meet
48:06one works very well
48:08predicts almost anything
48:09that you can do
48:10it's short distances
48:11and the other one
48:12predicts almost anything
48:13we see
48:14in relativistic astronomy
48:15most of the time
48:18gravity is completely
48:19separate from quantum mechanics
48:21gravity is so much weaker
48:22than the quantum forces
48:24on the nuclear level
48:25the black hole
48:26is the one place
48:27where gravity
48:28plays with all the other forces
48:30on an equal footing
48:30when you're getting close
48:32to the singularity
48:33maybe you actually
48:35never get to the point
48:36where you have
48:37an infinite density
48:38because in quantum mechanics
48:41you cannot have
48:42something infinitely small
48:43because it will always have
48:44space-time kind of fuzzy
48:45around that size
48:46but maybe
48:49what's happening there
48:50have some effect
48:51at the level
48:52of the event horizon
48:53and that's where
48:55we can probe
48:56with gravitational waves
48:57because when
48:58two black holes collide
48:59the two event horizons
49:01they merge
49:02and they are
49:03very excited
49:04and are shedding
49:05a lot of energy
49:06the shape of the gravitational waves
49:07that come out
49:08might carry
49:09a little bit of information
49:10of what's going on inside
49:12might
49:13we don't know
49:13but
49:15maybe we will find out soon
49:16Einstein didn't think
49:19we could detect
49:19gravitational waves
49:21and he didn't believe
49:22black holes existed at all
49:24even though they were born
49:25from his own theories
49:26now we know for sure
49:28that they do exist
49:30and they may reveal
49:31the inner workings
49:32of the universe
49:33and that's why
49:35black holes draw us
49:36because they represent
49:37what we don't know
49:38and they represent
49:40what we could know
49:41if I were
49:45to meet Einstein today
49:47I would tell him
49:47hey Albert
49:49Albert
49:49I'm sorry
49:50we proved you wrong
49:52I'm sorry
50:22you
50:26you
50:27you
50:32you
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