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  • Amanda Hallberg Greenwell: Okay.

  • Welcome to today's press conference brought to you

  • by the National Science Foundation

  • and the Event Horizon Telescope Project.

  • Thank you all for joining us today.

  • My name is Amanda Hallberg Greenwell,

  • I am the head of the National Science Foundation's

  • Office of Legislative and Public Affairs.

  • I would like to introduce today's distinguished panel.

  • Dr. France Cordova, Director of the National Science Foundation.

  • Sheperd Doeleman,

  • is the Event Horizon Telescope Project Director

  • of the Center for Astrophysics, Harvard and Smithsonian.

  • Dan Marrone is an Event Horizon Telescope

  • Science council member

  • and an Associate Professor of Astronomy

  • at the University of Arizona.

  • Avery Broderick is a member of the Event Horizon Telescope

  • Board and Wheeler Chair of Theoretical Physics

  • at the Perimeter Institute and Associate Professor

  • at the University of Waterloo. And Sera Markoff is a member

  • of the Event Horizon Telescope Council,

  • a professor of theoretical physics

  • at the University of Amsterdam

  • and she coordinates the EHT multi-wavelength workshop.

  • We will have time for questions after the panel concludes

  • so please hold all questions until that time.

  • I will now turn it over to Dr. Cordova.

  • Dr. France Cordova: Good morning.

  • Thank you for joining us at this historic moment.

  • I would like to give a special welcome

  • to the Director of the White House

  • Office of Science and Technology Policy,

  • Dr. Kelvin Droegemeier.

  • And from the National Science Board,

  • the current chair, Diane Souvaine and former chair,

  • Maria Zuber.

  • Today, the Event Horizon Telescope Project

  • will announce findings that will transform

  • and enhance our understanding of black holes.

  • As an astrophysicist, this is a thrilling day for me.

  • Black holes have captivated the imaginations of scientists

  • and the public for decades.

  • In fact, we have been studying black holes so long,

  • that sometimes it is easy to forget

  • that none of us have actually seen one.

  • Yes, we have simulations and illustrations.

  • Thanks to instruments

  • supported by the National Science Foundation,

  • we have detected binary black holes,

  • merging deep in space.

  • We have observed the episodic transfer of matter

  • from companion stars onto black holes.

  • Some massive black holes create jets of particles and radiation.

  • We have spotted the subatomic neutrinos

  • those jets can fling across billions of light-years.

  • But we have never actually seen the event horizon,

  • that point of no return after which nothing,

  • not even light can escape a black hole.

  • How did we get here?

  • Through the imagination and dedication of scientists

  • around the world willing to collaborate

  • to achieve a huge goal.

  • Through a large pool of international facilities,

  • and through long-term financial commitments from NSF

  • and other funders willing to take a risk

  • and pursuits of an enormous potential payoff.

  • Without international collaboration among facilities,

  • the contributions of dozens of scientists and engineers

  • and sustained funding,

  • the event horizon project would have been impossible.

  • No single telescope on earth has the sharpness to create

  • an un-blurred definitive image of a black hole's event horizon.

  • So this team did what all good researchers do, they innovated.

  • More than five decades ago,

  • other NSF funded researchers helped lead the development

  • of very long baseline interferometry,

  • which links telescopes

  • computationally to increase their capabilities.

  • This team took that concept to a global scale.

  • Connecting telescopes to create a virtual array,

  • the size of the Earth itself. This was a Herculean task,

  • one that involved overcoming numerous technical difficulties.

  • It was an endeavor so remarkable

  • that NSF has invested $28 million

  • in more than a decade,

  • joined by many other organizations in our support,

  • as these researchers shaped their idea into reality.

  • I believe what you are about to see

  • will demonstrate an imprint on people's memories.

  • The event horizon project shows the power of collaboration,

  • convergence, and shared resources,

  • allowing us to tackle the universes biggest mysteries.

  • Now I'm going to hand over this to our distinguished panel

  • starting with Dr. Shep Doeleman, EHT's Director.

  • [Applause]

  • Dr. Sheperd Doeleman: Thank you assembled guests,

  • black hole enthusiasts.

  • Black holes are the most mysterious objects

  • in the universe,

  • they are cloaked by an event horizon

  • where their gravity prevents even light from escaping,

  • and yet the matter that falls onto the event horizon

  • is superheated so that before it passes through,

  • it shines very brightly.

  • We now believe that super massive black holes, millions,

  • even billions in times the mass of our sun,

  • exist in the centers of most galaxies.

  • And because they are so small that we have never seen one,

  • they are though that they can outshine the combined starlight

  • of all the constituent stars in those galaxies.

  • The best idea we have of what they can look like come

  • from simulations like this.

  • The infalling gas that is superheated lights

  • up a ring of light where photons orbit the black hole,

  • and interior of that is a dark patch

  • where the event horizon itself prevents light from escaping.

  • The event horizon telescope project is dedicated to the idea

  • that we can make an image of this black hole.

  • That we can set a ruler across this shadow feature,

  • measure the photon ring and test Einstein's theory

  • where they might break down.

  • It also allows access to a region of the universe

  • we can study precisely the energetics

  • and how black holes dominate the cores of galaxies.

  • To do this, we worked for over a decade

  • to link telescopes around the globe

  • to make an Earth-sized virtual dish.

  • The event horizon telescope

  • achieves the highest angle resolution

  • possible from the surface of the earth,

  • it is equivalent of being able to read the date

  • on a quarter in Los Angeles

  • when we are standing here in Washington DC.

  • In April 2017, all the dishes in the event horizon telescope

  • swiveled, turned, and stared at a galaxy

  • 55 million light-years away, it is called Messier 87 or M87.

  • There is a super massive black hole at its core,

  • and we are delighted to be able to report to you today

  • that we have seen what we thought was unseeable.

  • We have seen and taken a picture of a black hole.

  • Here it is.

  • [Applause]

  • This is a remarkable achievement.

  • What you are seeing here is the last photon orbit,

  • what you are seeing is evidence of an event horizon,

  • by laying a ruler across this black hole,

  • we now have visual evidence for a black hole.

  • We now know that a black hole that weighs 6.5 billion times

  • what our sun does exists in the center of M87

  • and this is the strongest evidence that we have to date

  • for the existence of black holes.

  • It is also consistent, the shape of the shadow,

  • to the precision

  • of our measurements with Einstein's predictions.

  • The bright patch in the south that you see tells us

  • that the material moving around the black hole

  • is moving at light speeds,

  • which is also consistent with our simulations and predictions.

  • This image forges a clear link

  • now between super massive black holes

  • and the engines of bright galaxies.

  • We now know clearly that black holes

  • drive large scale structure in the universe

  • from their home in these galaxies.

  • We now have an entirely new way of studying general relativity

  • and black holes that we never had before

  • and as with all great discoveries,

  • this is just the beginning.

  • The imaging of a black hole doesn't come easily,

  • I can tell you that from personal experience

  • as can many people here in the audience.

  • It has required long-term developments, a committed team,

  • but it also required some very interesting cosmic coincidences.

  • Take for example the maelstrom you see before you,

  • the hot gas swirling around the black hole.

  • A photon has to leave from close to the event horizon,

  • travel through the hot gas infalling to the black hole,

  • and light rays of a millimeter length,

  • radio waves can make that journey.

  • Not all of them can.

  • Then that radio wave has to propagate 60,000 years

  • through the M87 galaxy, and then another

  • 55 million years through intergalactic space.

  • Then it winds up in the Earth's atmosphere

  • where it's greatest enemy, the greatest danger,

  • is that it'll be absorbed by water vapor

  • in our own atmosphere.

  • So the event horizon telescope uses telescopes at high,

  • dry sites so that we can see allows us

  • to see the photons that have traveled to us so far.

  • So far so good, we have the photons.

  • But the M87 shadow is very, very small

  • compared to the galaxy that surrounds it.

  • So in order to see it, we needed to build a telescope

  • as large as the Earth itself given the wavelength of light

  • we were trying to observe.

  • And to do that, we use a technique

  • called very long baseline interferometery

  • which you can see a schematic of here.

  • Radio waves from the black hole hit radio telescopes,

  • where they are recorded with the precision of atomic clocks

  • that lose only one second every 10 million years.

  • When you've registered these radio waves so precisely,

  • you can then store them on hard disk drives,

  • send them to a central facility

  • where they can be combined precisely.

  • It's exactly the same way that a mirror

  • used in an optical telescope

  • reflects light perfectly and in synchronicity to a single focus.

  • When we do this, we can synthesize a telescope

  • that has the resolving power as though we had

  • one the size of the distance between these telescopes,

  • truly turning the earth into a virtual telescope.

  • All of the sites that we used can be seen here.

  • We have telescopes from Hawaii to Arizona to Mexico to Chile,

  • the South Pole, and in Spain.

  • But even these, even this broad global network

  • is not enough by itself to make an image.

  • You can think of them being silvered spots

  • in a large global mirror.

  • The key is that the earth turns. During a night of observing,

  • we are able to sweep out more baselines,

  • more coverage of this virtual mirror to make our image.

  • So on the left, you will see the earth turning.

  • Every pair of telescopes

  • provides us with one point on the center panel,

  • which fills in the Earth-size virtual lens and

  • on the right you see the evolving image.

  • The more and more data we get,

  • the more we fill in this virtual mirror,

  • the sharper our view of the black hole becomes

  • until you wind up

  • seeing what we have as the final image there.

  • So we have taken advantage of a cosmic opportunity,

  • it is remarkable when you think about it.

  • Light that left near the event horizon

  • traveled all the way through intergalactic space,

  • it hit our telescopes.

  • The earth just happens to be the right size

  • so we get resolving power

  • so that we can see the black hole and M87,

  • whose mass and distance let us observe it.

  • And then the earth turns to fill in our mirror

  • so that we can make this image. It is truly remarkable,

  • it is almost humbling in a certain way.

  • We are four members of a large collaboration

  • and it is our distinct honor

  • to be here to represent that collaboration.

  • We are 200 members strong, we are 60 institutes,

  • and we are working in over 20 countries and regions.

  • We consider ourselves really to be explorers,

  • through international cooperation and innovation,

  • we have exposed part of the universe

  • that we thought was invisible to us before.

  • It is our responsibility to report these findings

  • and we are doing that today to the National Science Foundation,

  • to our funding agencies, international and foundations,

  • and to all people who support pioneering research,

  • and also to the taxpayers.

  • Nature has conspired to let us see

  • something that we thought was invisible.

  • This is a long sought goal for us and we find it tremendous,

  • and we hope that you will be inspired by it, too.

  • Thank you, and now let me introduce Dan Marrone

  • who has literally gone to the ends of the earth

  • to collect some of the data we've seen here today.

  • [Applause]

  • Dan Marrone: Thanks Shep.

  • So the heart of our measurement is, of course, the EHT array.

  • It would have been an expensive

  • and enormous undertaking to build a dedicated array

  • just to do this experiment, so we didn't do that.

  • Instead we built an international partnership

  • that allowed us to use submillimeter telescopes

  • are over the world,

  • in fact we used basically all of the submillimeter telescopes

  • in the world to make this measurement.

  • One that none of them could have done on their own.

  • When you take a heterogeneous collection of telescopes

  • and build them into one giant telescope,

  • it provides a lot of technical challenges.

  • So In the years leading up to our 2017 experiment,

  • we went telescope by telescope all over the world,

  • installing the specialized hardware we needed to do this.

  • Most had detectors we could use,

  • but almost none of them had the atomic clocks we need,

  • and certainly none of them had the very fast data recorders

  • that we use.

  • Some places, we had to do even more.

  • A good example is the ALMA telescope in Chile,

  • It's a 66 telescope array,

  • it's by far our most sensitive telescope

  • and its sensitivity is transformational

  • for our experiment. But in order to use it,

  • we didn't just need the basic hardware,

  • we also needed a special piece of hardware

  • that can sum the light from all the telescopes

  • before we send it to our reporters.

  • This alone was a many year project

  • using an international collaboration of people

  • from the EHT and also from the ALMA project.

  • Another good example is the South Pole telescope.

  • The South Pole is a special place in our array.

  • It is so far south that it doubles

  • the resolution of EHT for sources it can see.

  • But the SBT was designed

  • to do a completely different kind of measurement,

  • it studies the cosmic microwave background,

  • so its detectors are not the detectors we need.

  • So in addition to bringing down an atomic clock

  • and all of the tens of crates of hardware that we needed,

  • we had to build a special receiver

  • that would detect the light the way we needed it detected,

  • special optics to relay the light,

  • and install it and get it to work in the cold

  • and sometimes harsh Antarctic environment.

  • This was many years of work for many of us,

  • many trips down for myself and graduate students

  • and post doc and other engineers in the EHT team,

  • but at the end of it, we had a South Pole telescope

  • that could be an EHT station.

  • Now getting the sites to work isn't the end of the process.

  • We also had to test them all because in VLBI

  • you really only get one shot, everything has to be working

  • exactly right when the script starts.

  • So we spent years taking site by site, pairing them up

  • and making sure that our VLBI observations would work.

  • The last of these observations was in January 2017.

  • By March 2017, we knew that test had worked,

  • and we were ready to go.

  • The image that Shep showed was from April 2017,

  • from that campaign,

  • we sent our team to the telescopes all over the world,

  • their job was to turn everything on, do very extensive testing,

  • and then be there to do the observations.

  • But even with all of that in place,

  • we still had to wait for weather.

  • And my experience with ten years of doing these observations

  • is that the weather is usually the place where we fail,

  • we have to have good weather in Hawaii and Spain

  • at the same time, in Arizona and in the South Pole.

  • That is a lot to ask.

  • But in 2017, we were very lucky.

  • Our first three days of observations

  • were some of the best weather we have ever seen.

  • For a ten day campaign, we were done in only seven,

  • taking all of the data that we wanted.

  • At the end of that we had five petabytes of data recorded.

  • It was recorded on more than 100 of these modules,

  • and it amounts to more than half a ton of hard drives.

  • Five petabytes is a lot of data.

  • It is equivalent to 5000 years of MP3 files,

  • or according to one story I read,

  • the entire selfie collection

  • over a lifetime for 40,000 people.

  • The image you saw though isn't five petabytes in size,

  • it is a few hundred kilobytes,

  • so our data analysis has to collapse

  • this five petabytes of data into an image

  • that is more than a billion times smaller.

  • We do that in many steps, the first of those steps

  • is to get these modules to our correlators in Westford,

  • Massachusetts and Bonn, Germany.

  • The fastest way to do that is not over the internet

  • it's actually to put them on planes,

  • there is no Internet

  • that can compete with petabytes of data on the plane.

  • Once they are there, the correlators job is to find

  • the exact same wave front of light

  • arriving from the black hole at each telescope.

  • Once it's found,

  • small timing corrections that line up those waves,

  • we can condense our data, we can average it,

  • and we reduce the volume by 1000.

  • Now we're at terabytes, a much more familiar unit.

  • But we have a lot more work to do,

  • the data still has imperfections at that point,

  • both from the instruments themselves,

  • and from the atmosphere above the telescopes.

  • And so we do something called fringe fitting,

  • we do this in the cloud with cloud

  • computing which lets us do it in days, instead of weeks.

  • We calibrate the data

  • so that we know exactly how bright our sources are.

  • And I'm speaking of this as though it is just computer work,

  • but this was actually a very significant project

  • for a subset of our team,

  • primarily junior people, postdocs and graduate students

  • and they deserve an enormous amount of credit

  • for their diligence and dedication

  • because without it we couldn't have made an image.

  • Once we are done with that,

  • we can finally go to the imaging stage.

  • Now, imaging with an interferometer

  • isn't as simple as downloading a picture from your camera.

  • Fortunately, the math that we use for it

  • has been around for more than 200 years,

  • the principle is well understood.

  • The methods though, as with everything with this project

  • are a little tricky for our data,

  • so in order to get the image,

  • there has been years of image algorithm development

  • that has been essential to our results.

  • At this point in history,

  • we have many different image algorithms to choose from,

  • they have different strengths and weaknesses,

  • it just depends on the character of the data.

  • And so the way we approached the imaging stage,

  • is we set up four teams all over the world,

  • they were collaborating,

  • each team is representing many parts of the world,

  • and we told them, don't talk to each other or anyone else,

  • choose with whichever algorithms you think are best

  • and make images of these data.

  • Then, in the summer of 2018,

  • we brought everyone back together.

  • Had a very exciting meeting at the EHT imaging workshop

  • in Cambridge, Massachusetts. If you couldn't be there,

  • you certainly called in from the Internet

  • because you wanted to see the presentation.

  • And in a very exciting presentation

  • we revealed to the other teams

  • and to ourselves what we'd found.

  • And what we saw in those images were four very similar pictures,

  • looking almost exactly like the one you see today.

  • An emissive ring surrounding the shadow of a black hole.

  • It was a wonderful day of science

  • and I'm glad that after a few more months

  • of very careful checking and paper writing,

  • that we are finally able to share with you today.

  • I would like to hand off to my colleague,

  • Avery Broderick, to talk about the interpretation.

  • [applause]

  • Avery Broderick: Thank you Dan.

  • It is an enormous pleasure to be with you this morning

  • to share in this extraordinary moment.

  • As Shep said, we have now seen the unseeable,

  • now what does it all mean?

  • Every photon in these first EHT images

  • began its journey in a churning maelstrom

  • embedded in the most extreme environment

  • in the known universe, the vicinity of a black hole.

  • And M87 the crucible in which these photons were born,

  • was empowered by the black hole in two distinct

  • but related ways.

  • First, via necretion flow. A violent disc of orbiting gas

  • driven inextricably toward the event horizon.

  • By the time the material was making its final plunge

  • it is crashing into itself at nearly light speed,

  • transforming the gas into 100 billion degree plasma.

  • Second, through astrophysical jets.

  • Narrow beams of outflowing material speeding away

  • from the black hole at nearly the speed of light.

  • These jets are powered by black hole spin,

  • rotating black holes drag everything,

  • gas, magnetic fields and photons about themselves,

  • driving these paradoxical structures

  • whose cosmic importance will be discussed by my colleague,

  • Sera Markoff.

  • In M87, one of these jets is pointed very nearly toward us.

  • The EHT images are influenced both

  • by these bright emitting regions,

  • the rotating accretion disk and outflowing jets

  • and by gravity itself.

  • In general relativity, radio waves fall just as apples do,

  • typically this effect is exceedingly small,

  • but black holes are gravity run amok.

  • The radio waves we see in these first images

  • orbited the black hole

  • before beginning their 55 million year journey towards us.

  • This results in the dark shadow or silhouette

  • cast by the black hole's event horizon upon the emission

  • from the accretion flow in the jet.

  • Importantly, the size and shape of the shadow

  • is determined by gravity alone.

  • General relativity makes a clear prediction

  • for both of these features.

  • To within 10%, the shadow should be circular.

  • With the diameter determined solely by mass,

  • multiplied only by fundamental constants.

  • However, as with all voyages of discovery,

  • when we began this expedition of the mind,

  • we did not know what we would find.

  • Were Einstein wrong,

  • were the heart of the M87 not a black hole,

  • its silhouette could have been very different, misshapen,

  • mis-sized, like those seen here, or even simply missing.

  • Changing gravity changes how light bends,

  • and thereby changes the shape of the shadow.

  • In April, 2017, this was the dog that did not bark.

  • The shadow exists, is nearly circular,

  • and the inferred mass matches estimates

  • due to the dynamics of stars 100,000 times farther away.

  • Today general relativity has passed another crucial test.

  • This one spanning from horizons to the stars.

  • The shadow is surrounded

  • by a bright ring of enhanced emission,

  • those photons that just escaped the black hole's clutches.

  • The properties of this ring like feature result

  • from the astrophysical drama that unfolds on gravity's stage.

  • To understand these dramas, over the past three years,

  • the EHT collaboration has undertaken an unprecedented

  • simulation effort at research institutions across the globe.

  • This has generated the largest collection of simulations

  • ever assembled of the accretion flow

  • and jet launching region in M87.

  • The southern brightness excess arises directly from near

  • light speed rotational motions near the black hole.

  • Regions that move toward us

  • at nearly the speed of light are bright.

  • Those that are moving more slowly or away are dim.

  • From these,

  • we have inferred the sense of rotation of the black hole.

  • In M87, the black hole spins clockwise.

  • Moreover, the excellent quantitative agreement

  • between the EHT images and generic theoretical expectations

  • of a bright crescent like feature

  • with a dark interior provide significant confidence

  • in our interpretation. The object of the heart of M87,

  • the object that powers M87's jets,

  • is a black hole like those described by general relativity.

  • Importantly in combination with infrared

  • and optical flux measurements,

  • we can now rule out a dim but otherwise visible surface.

  • That is, this does appear to have the defining feature

  • of a black hole,

  • the event horizon, that point of no return.

  • Today, several complementary windows

  • have opened upon black holes,

  • science fiction has become science fact.

  • Together, two of these windows, the EHT and LIGO,

  • which reported the first detection of gravitational waves

  • a short three years ago,

  • have verified another key prediction

  • of Einstein's theory of gravity.

  • Despite varying across of factor of billion en masse,

  • known black holes

  • are all consistent with a single description.

  • Black holes big and small are analogous in important ways.

  • What we learn

  • from one necessarily applies to the other.

  • At this point, I would like to hand the story off

  • to Sera Markoff,

  • who will describe the broader astrophysical implications

  • of these first EHT images. Thank you.

  • [Applause]

  • Sera Markoff: Thank you Avery.

  • So black holes may be the most exotic consequence

  • of general relativity but these bizarre sinkholes

  • in the actual fabric of space-time turn out to be,

  • have a lot of consequences of their own,

  • which I'm going to talk about today.

  • That is because black holes

  • are major disruptors of the cosmic order

  • on the largest scales in the universe,

  • they are helping mold to the shape of galaxies

  • and clusters of galaxies.

  • What we've now confirmed, as Avery was saying,

  • that general relativity itself does not change

  • when we look at different black hole masses,

  • it turns out the impact of a black hole

  • will actually change a lot. And so if we want to understand

  • the role of black holes in the universe,

  • then we need to have accurate determinations

  • of the black hole masses.

  • This has been a problem up until now.

  • So, our mass determination

  • by just directly looking at the shadow has helped resolve

  • a long-standing controversy in measuring the mass of M87.

  • There's been two independent methods,

  • one, both, basically looking at the motion of either

  • gas or stars,

  • but they ended up giving different answers.

  • Our determination of 6.5 billion solar masses lands

  • right on top of

  • the heavier mass determination from stellar motions

  • so this will also help resolve the discrepancy

  • that can lead to better mass determinations

  • for other more distant black holes

  • when we can actually see the shadow.

  • So getting to the impact of this is important because

  • M87's huge black hole mass makes it really a monster,

  • even by super massive black hole standards.

  • So you're basically looking at a super massive black hole

  • that is almost the size of our entire solar system.

  • And in fact that's part of the reason why we can see it,

  • even though it is so far away.

  • But now if we zoom back out to the more cosmic perspective

  • of the host galaxy of this black hole,

  • the galaxy is made of billions of solar systems,

  • so on those scales the black hole itself is minimally small,

  • it is about 100 million times smaller than the galaxy.

  • And if it were a dormant black hole

  • like the super massive black hole

  • in the center of our own galaxy, Sagittarius A*,

  • then the galaxy would have no way of knowing it is there,

  • it would basically be like a pebble in a shoe.

  • But when the black hole is activated

  • by gravitationally capturing material,

  • it starts to convert that fuel into other forms of energy,

  • with the efficiency that can be almost 100 times better

  • than nuclear fusion that powers stars like our Sun.

  • So when that happens in these active phases,

  • black holes temporarily become

  • the most powerful engines in the universe,

  • and they go very quickly from being a pebble in a shoe

  • to a thorn in the side of the galaxy, literally.

  • And the thorns in this case being the jets

  • that Avery was mentioning.

  • In the most extreme cases, these jets can actually

  • penetrate into the entire galaxy and well beyond.

  • But the power that is coming out,

  • we can't see with our own eyes, so if we want to understand them

  • we have to look in other wavelengths,

  • so we look with telescopes

  • across the electromagnetic spectrum.

  • So I'm going to give you an example of this.

  • This is another very active black hole system,

  • and it is a combined image,

  • so you see in white from NASA's Hubble telescope,

  • the elliptical galaxy, Hercules A, in the center,

  • and then overlaid in blue is the radio waves

  • from the National Science Foundation's

  • very large array, and these radio waves

  • are basically tracing magnetic fields in space,

  • so that tells us that these jets are enormous fountains

  • of magnetized material

  • that are being sprayed out from the black hole,

  • not the black hole itself, but near the black hole,

  • nearly at the speed of light.

  • And these particular jets are 100 million times bigger

  • than the black hole that launches them.

  • Now if we add another layer, we are going to look

  • in the X-rays now from NASA's Chandra telescope,

  • and X-rays are probing extremely hot gas,

  • like billions of degrees

  • so we're seeing the entire system

  • is embedded in a halo of hot gas.

  • And we can use this information to calculate how much energy

  • the jets have to have to bore through all this material.

  • What we find is that the jets are carrying the equivalent

  • of 10 billion supernova in energy

  • deposited over one of these active cycles.

  • So this is,

  • these kinds of interactions are basically very important

  • because this tiny black hole on these scales

  • is somehow launching these structures

  • and also managing to heat the gas

  • to prevent stars from forming.

  • And since galaxies grow by forming more stars,

  • this has the effect of truncating galaxy growth

  • and we think it is through these types of interactions

  • that black holes help shape the largest structures,

  • galaxies, and clusters of galaxies

  • and make them look the way they do today.

  • Now M87 is in a much more modest active state but as you can see,

  • this is also from Hubble,

  • it is still managing to launch the magnificent jets,

  • these jets are emitting across the electromagnetic spectrum

  • as well, so we need this information

  • to be able to fully understand the system.

  • But if we zoom way out now to the cluster of galaxy scales,

  • this is another combined image where you see red

  • in radio and blue in X-ray,

  • you just see just a mess of structures,

  • and we think this is telling us

  • about M87's black hole's past interactions,

  • really affecting the cluster scales,

  • timescales on hundreds

  • or tens of hundreds of millions of years.

  • So until now we always thought that black holes were behind

  • these large structures driving these engines,

  • but we never knew. And now we with EHT

  • we have direct evidence of the root of these problems,

  • and we can look at this and we can now start to make,

  • to understand combining strong gravity, magnetic fields

  • and looking at atomic level processes to understand

  • how these processes interplay and conspire

  • to make these enormous structures

  • that are basically affecting the larger scales of the universe.

  • And so to capture all of this information,

  • we need to combine our observations

  • with those across the multi-wavelength spectrum.

  • As you heard from Dan, there are a lot of complexity

  • in these observations, and we added to that

  • by doing a complicated Sudoku of coordination

  • with many facilities across the globe and also in space.

  • This is similar to the campaign

  • that was run with LIGO for gravitational waves.

  • It's very important to combine signals

  • both from photons and particles,

  • so by doing this, we expect EHT is going to play an active role

  • in this new era of international multi-messenger astronomy.

  • So looking to the future, the same observations we took

  • in 2017 for M87 also included this dormant black hole

  • in our galactic center, Sagittarius A*.

  • And by looking at two black holes at opposite extremes

  • in activity range,

  • especially combining this with multi-wavelength information,

  • we can better understand

  • the ebb and flow of influence of black holes

  • in the long course of our history in the universe.

  • Anyway, thank you very much,

  • I'm going to hand this back over to Shep

  • who's going to say a few words.

  • [Applause]

  • Dr. Sheperd Doeleman: Thank you everyone,

  • I just want to point out that

  • when we first started the event horizon telescope project,

  • the group was small and I think it had to be small and nimble

  • to carry out precursor experiments

  • and develop the first kinds of techniques and instrumentation

  • that enabled us to move the field forward.

  • But, over the past decade,

  • the greatest accomplishment has been the building of a team,

  • and as I said before, we're more than 200 people strong,

  • many institutes, over 20 countries and regions.

  • If you want to reduce petabytes of data,

  • if you want to develop new imaging algorithms,

  • if you want to image a black hole,

  • then you need a large team.

  • It has included many early career scientists,

  • senior scientists, and many of them were here with us today.

  • So I would like to ask everyone who is associated

  • with the event horizon telescope

  • to please stand up so everybody in the media

  • can see who has done this work.

  • [Applause]

  • It is a true pleasure and privilege

  • to work with this crew.

  • I urge all the media to go seek them out

  • to learn how the sausage was actually made,

  • how the black holes were actually imaged.

  • I also want to say something in particular

  • about funding and support,

  • this has been a high risk but high payoff endeavor,

  • sometimes you have to kiss a lot of frogs

  • before you get to the Prince,

  • before you get to the black hole image.

  • You need supporters, you need funders who will stand by you

  • for long periods of time, who take the long view,

  • who understand that basic science,

  • never goes out of style.

  • and who also understand that basic science,

  • you never know when it is going to pay off,

  • but ultimately it usually does,

  • and you have to play the long game.

  • We have wonderful partners with the National Science Foundation,

  • with our international funding agencies and foundations

  • and our hat is off to them for sticking by us for so long,

  • and we look forward to greater things with EHT

  • as we continue to sharpen our focus on black holes.

  • Thank you.

  • [Applause]

  • Amanda Hallberg Greenwell: Thank you all very much.

  • One note before we take questions,

  • several of our panelists and many of their EHT collaborators

  • will appear this week in a documentary

  • which has followed efforts of the EHT for the past 2 years.

  • The film will show viewers how Shep Doeleman and his team

  • reached the groundbreaking moment.

  • The documentary is called Black Hole Hunters

  • and it will premiere this Friday,

  • April 12, at 9 PM Eastern on Smithsonian channel.

  • We will now take questions from the audience until 10 a.m.

  • Please raise your hand, wait for a microphone,

  • and identify yourself and who you are with you

  • before asking your question.

  • Seth Borenstein, The Associated Press:

  • Two part question, please.

  • First, this is M87, you have two targets initially.

  • Have you seen anything,

  • have you captured any images of Sagittarius A* yet

  • and have not released them for whatever reason?

  • Or have you not gotten those images?

  • Second, one of the keys I understand,

  • when you look at this distinct edge of the photon ring,

  • not being a scientist, this looks fairly fuzzy,

  • how distinct is this edge to you?

  • is it distinct enough to notice

  • the effect of gravity or not?

  • How close does it pass to whatever measurement you use

  • for sharpness of that edge?

  • Dr. Shep Doeleman: I will start off with the first part.

  • Sagittarius A* is also very interesting target,

  • we can see the event horizon, we should be able to resolve it.

  • It is complex. M87 was in some sense

  • the first source that we imaged so we went with that.

  • It is a little bit easier to image

  • because the timescales are such that it doesn't change much

  • during the course of an evening.

  • So we are very excited to work on Sagittarius A*.

  • We are doing that very shortly, we are not promising anything

  • but we hope to get that very soon.

  • On the point about the circularity of the image, NGR,

  • I would like to ask Avery answer that.

  • Avery Broderick: Your question

  • was on the sharpness of the edge.

  • So we have actually spent a considerable amount of time

  • trying to ascertain the particular details of this ring

  • like or crescent like feature.

  • And the sharpness, it falls off in less than 10% of the radius,

  • that's about the instrumental resolution

  • that we practically have.

  • So insofar as we can tell, it drops off nearly instantly

  • and does look then very much like a black hole shadow.

  • Seth Borenstein: So even though it looks fuzzy, it isn't.

  • Avery Broderick: That's right.

  • Alan Boyle, GeekWire: Hi, I'm Alan Boyle with GeekWire.

  • I wanted to ask, following up on that idea of the image,

  • are there things you might be doing

  • to enhance further the quality of the image?

  • Might there be more telescopes added to the network,

  • or are you using different data processing techniques

  • to get an even sharper image?

  • Dr. Sheperd Doeleman: I will answer the first part of that.

  • We think we can make the image

  • perhaps sharper through algorithms

  • and I'll leave that to Dan.

  • But we are embarking on a wonderful new series

  • of putting new telescopes in different places on the Earth,

  • so if you add more telescopes,

  • you build out that virtual Earth-sized mirror.

  • And it goes to N-squared,

  • so if 'n' is your number of stations,

  • then the number of points you get in your virtual mirror

  • goes to n-squared so even adding two or three more stations

  • in just the right places will increase

  • the fidelity of the image a lot. The other thing I would add is

  • that if you have higher frequencies,

  • which the EHT is going to do soon,

  • then you get an even higher angular resolution.

  • Dan Marrone: I think the biggest improvement

  • we'll make will be through adding new telescopes,

  • and the higher frequency observations

  • will be very exciting. As I said, in my section,

  • the methods of imaging are complicated.

  • So depending on what you are interested in,

  • if you're interested in the sharpness of the ring,

  • you can approach the imaging process slightly differently

  • and make a less blurry looking picture.

  • Tariq Malik, Space.com: Thank you very much.

  • Tariq Malik with Space.com. I think for Shep.

  • You said in your opening,

  • that this was seeing the unseeable,

  • and it's been a good long time to prove this concept out.

  • I'm just wondering for a moment, as a scientist,

  • what you, what your team members,

  • what it felt like to see that image for the first time.

  • Did you have a party? Did someone cry?

  • It is an amazing achievement, how would you relate that?

  • Dr. Sheperd Doeleman: That is a great question.

  • We have been at this for so long,

  • there was such a buildup,

  • there was a great sense of release, but also surprise.

  • When you work at this field for a long time,

  • you get a lot of intermediate results.

  • We could have seen a blob and we've seen blobs.

  • You could have seen something that was unexpected,

  • but we didn't see something that was unexpected.

  • We saw something so true,

  • we saw something that really had a ring to it.

  • If you can use that term of phrase

  • and I think it was just astonishment and wonder,

  • and I think any scientist in any field

  • would know what that feeling is,

  • to see something for the first time.

  • To know that you've uncovered part of the universe

  • that was off-limits to us.

  • When that happens, it is an extraordinary feeling.

  • I think for every one on the team.

  • Dr. France Cordova: I will just add,

  • as an astrophysicist,

  • this is the first time that I saw this image right now

  • because they wouldn't let NSF see it.

  • It did bring tears to my eyes so this is a very big deal,

  • I didn't really know what to expect.

  • It was so cool. It is an amazing image.

  • Congratulations.

  • Hi, Jay Bennett with Smithsonian Magazine.

  • You mentioned just now that this was kind of the perfect image,

  • there wasn't really any surprises to it,

  • it was the exact ring

  • that you expected from general relativity.

  • Was there anything about it at all

  • that was surprising or unexpected?

  • Or was it really just kind of what you were looking for?

  • Dr. Shep Doeleman: Well in broad brush, as Avery said,

  • it has verified Einstein's theories of gravity

  • in this most extreme laboratory.

  • But, there are some very interesting things

  • that we want to follow up with,

  • there are asymmetries around the ring,

  • the brightness in the southern part,

  • so there will be a lot of future work on this

  • to sharpen our focus on gravity.

  • Avery Broderick: So, first, I have to admit,

  • I was a little stunned that it matched

  • so closely the predictions that we had made.

  • It is gratifying, sometimes frustrating.

  • But this is the beginning, we are asked a moment ago

  • about how we felt and I think it was a cathartic release

  • that finally things are working,

  • but also the anticipation and the amazing science

  • that we are going to do by studying this image closely,

  • and by repeating the experiment.

  • In that sense, we will be able to improve the precision

  • with which we can probe general relativity, etcetera,

  • and there we may find these unanticipated surprises.

  • Chris Lintott, The Sky-At-Night: Chris Lintott

  • from BBCs The Sky at Night.

  • Thank you for releasing the papers

  • alongside the press images. The first image on the paper

  • there shows four different images from four different days,

  • and it seems to me there are hints of changes from day today,

  • are those real?

  • Can you say anything about time variability at this point?

  • Dan Marrone: There are two sets of four images,

  • the earliest image in the imaging paper

  • shows those four preliminary images that I spoke about.

  • The four different teams presenting their results.

  • Those differ slightly from the final answer

  • partially because that was still an engineering data release,

  • it wasn't the final data.

  • From day-to-day, we have tried to establish

  • how well we can trust the differences between the days,

  • they seem real but at the moment,

  • it is hard for us to interpret them.

  • So we hope, the timescale for variation from M87 is very slow,

  • so we hope that by looking at the data we got in 2018

  • we will be able to see if anything important has changed.

  • Dr. Shep Doeleman: Can I add to that?

  • I would also add that Sera pointed out,

  • the multi-wavelength is a key piece of the puzzle,

  • so when we observed with EHT on the very smallest scales,

  • we also want to observe the multi-wavelength,

  • x-rays and the longer waves of radios on the larger scales.

  • Sera, did you want to expand on that?

  • Sera Markoff: We actually didn't highlight that

  • in these first six papers.

  • We did use information from the x-rays

  • to help constrain some of the models

  • but we have an enormous amount of multi-wavelength data

  • that goes with these data sets

  • and so I think you can expect to see quite a lot of studies.

  • They'll help us understand some of the variability

  • that you're asking about as well.

  • M87, we're actually catching it in a quiet point.

  • We can tell this from historical multi-wavelength data

  • and compared it with what we've got.

  • So I think in a lot of ways it comes back

  • to the fact that we just got lucky.

  • Had it been flaring,

  • we might be seeing something a lot different.

  • It might have blocked the hole as well.

  • It was flaring even about seven years ago or so.

  • Arthur Friedman: My name is Arthur, [unclear] reporter.

  • I have a general question about black holes.

  • We are talking about the density and mass of the black holes,

  • do you have any sense of the general length

  • and width of the different black holes?

  • Are we talking like billions of light-years

  • across in terms of the width,

  • or is it billions of miles? What is the size?

  • And what keeps the density together in each black hole?

  • Do you think that larger black holes have a harder time

  • keeping the density intact versus smaller black holes?

  • Avery Broderick: The answer to your first part

  • of your question, how big is the black hole?

  • It is about 1 1/2 light days across.

  • So, not light-years, measured in a day.

  • That means that practically it appears

  • to evolve on week timescales,

  • so we see substantial changes in principle

  • in timescales of maybe two weeks, 1 1/2 weeks.

  • What holds it all together?

  • All black holes are the same in this regard.

  • It's all gravity. Black holes are all about gravity.

  • And, once you get that much mass

  • collected into that smaller region,

  • and how small depends on the mass, okay.

  • So if I make a black hole ten times more massive,

  • the region I have to reach it is ten times larger.

  • If I make it a billion times less massive,

  • the region is a billion times smaller.

  • Once you have gotten that much mass that close together,

  • gravity runs the show and there's no other force

  • that we know of that will stop it.

  • And everything collapses down in the center in principle

  • to a singularity but behind it, the horizon,

  • it is hard to reach.

  • When you go there, you don't get to come back

  • and tell us what you've seen.

  • Emilio Rodriguez, Nature Magazine: I'm just wondering

  • if these images can help us understand

  • how black holes produce jets and also,

  • do you see this thing evolving over time,

  • is it changing over time or do you just see it as fixed?

  • Sera Markoff: I think this comes back

  • to one of the earlier questions.

  • What we are seeing is effectively,

  • when you look in different wavelengths,

  • you're picking out different scales of the system

  • and then also the fact

  • that we are using a planet-sized telescope,

  • means we have the extreme precision

  • to see the route very close to the black hole.

  • That region is all magnetized plasma,

  • and we think that the jets are being launched

  • effectively by some sort of squeezing of the magnetic plasma

  • towards the black hole and then maybe an enhancement

  • from the spin of the black hole itself.

  • We are looking directly at this region,

  • so we do anticipate that this image,

  • we haven't really begun to see the full analysis

  • but we've done a lot of work so far, different groups

  • within the team have been doing simulations.

  • And the effect, the expectation of that

  • is that we will be making models

  • and comparing them again especially again

  • also to multi-wavelength data on the larger scales,

  • and looking for variability.

  • Looking for any hints at the underlying physics

  • that is really going on.

  • We have a pretty good idea in the broad

  • stroke of what is happening but there is a lot of debate

  • about the actual processes near the black hole.

  • And so that is going to be the next steps,

  • I think you can expect quite a lot coming out

  • in the coming period on that.

  • Anna Humphrey, TCWilliams High School: I was wondering,

  • this is obviously an incredible feat of global collaboration

  • in the scientific community,

  • and do you see this as being a model for science going forward?

  • If so, what are the challenges

  • and what are some of the things we can hope to accomplish?

  • Dr. Sheperd Doeleman: I'd like to say something about that.

  • That's a great question.

  • VLBI, Very Long Baseline Interferometry,

  • which as Dan explained is the whole technique that we use is,

  • by its very nature, a cross-border activity.

  • We don't pay attention to where the telescopes are,

  • just that they are high enough and above the water vapor.

  • And that they're manned by scientists

  • who share our common vision.

  • In that sense, we built this team,

  • this 200+ member team

  • by selecting experts from everywhere.

  • I think it is a really good model

  • for how we can do distributed science.

  • We spend a lot of time on video cons.

  • We have published papers with people

  • that we have never met before,

  • but we consider them our true and trusted colleagues.

  • That happens because we have the ability to reach out

  • and form a distributed network of scientists.

  • So I think it is a good model.

  • Question: Thank you for taking my question.

  • My name is...from NHK Japanese Public Broadcasting.

  • I have a question about international collaboration.

  • I understand this is the enormous work of collaboration,

  • but can you tell me more about the detail

  • of each country's contribution? Especially Japan.

  • Dr. Shep Doeleman: I can say something about that,

  • I work very closely with many people

  • at the National Astronomical Observatory of Japan and others.

  • Japan has played a very key role,

  • as have a number of countries.

  • Japan, for example, was one of the key members

  • for the project that phased up ALMA,

  • that took all the dishes in the ALMA array

  • in the high Atacama desert

  • and then made them essentially one dish,

  • that we can record on one set of equipment, that was huge.

  • They have been a key partner in the imaging techniques

  • and pushing that forward, too.

  • But, the key is that each country, each region,

  • each group, each institute brought something in kind

  • and they brought their expertise and they brought their work.

  • At the end of the day, you just need this stuff to get done.

  • Everyone came with a full heart really,

  • and the expertise and the energy to make this image

  • that we presented to you today.

  • Question: [unclear] from Wakefield High School:

  • I was wondering, if nothing travels

  • into the black hole

  • at the speed of light, other than light itself,

  • how does the black hole pull light into itself, I guess?

  • And also, you guys have mentioned how the M87

  • is 55 million light-years away,

  • then how does the time work from capturing the light

  • from here to itself?

  • Dr. Shep Doeleman: It just takes light 55 million years

  • to get here,

  • so when we see M87 and the image you saw,

  • that is what it looked like 55 million years ago.

  • That is the last part of your question.

  • The first part, anyone?

  • Avery Broderick: So light can't escape the horizon

  • because in some sense, space-time itself

  • is flowing through the horizon

  • at the speed of light at that point.

  • This is one of the beautiful elements

  • of Einstein's theory of gravity,

  • is that space is no longer a static stage

  • on which things happen but a dynamical participant.

  • And you can think about it moving and flowing,

  • and black holes drag it around when they spin

  • and flows through the horizon when they are,

  • even when they're static.

  • So those photons trying to climb

  • out of the gravitational potential well,

  • outside the horizon can do so because they can go faster.

  • But once you cross the horizon, they're dragged in,

  • just like sound waves across a waterfall.

  • Hi, Emily Converse, Science News: I was wondering

  • if you could talk

  • in just a little bit more detail in your future plans.

  • I know you mentioned adding some telescopes

  • and other frequencies.

  • Maybe you could just give some more detail

  • about when and what you are looking at.

  • Dr. Sheperd Doeleman: Well, I would point out that April,

  • 2017 we had eight telescopes in six geographic locations.

  • And in 2018, we added another telescope,

  • the Greenland Telescope which dramatically increased

  • our coverage of the north of M87.

  • And we are going to add a new telescope in Dan's backyard,

  • the Kitt Peak Observatory in Arizona.

  • These will all increase the imaging fidelity.

  • They will fill out that virtual mirror

  • that we are trying to build.

  • That is important for something that Sera described,

  • which is the jets.

  • We see this ring, but it's difficult for us

  • to make the firm connection

  • to the larger scaled jets that Sera showed.

  • By adding more telescopes,

  • at intermediate and longer baselines

  • we'll be able to extend the image of that shadow out

  • to where it connects to that jet where we know it has to.

  • So that is one area that we are expanding into

  • and the increased frequency of observation.

  • We observed a one millimeter wavelength,

  • now we want to move to .87 millimeter wavelength.

  • It sounds like a small jump

  • but it increases your angular resolution,

  • the resolving power by over 30%, 50%.

  • So, you wind up sharpening your image

  • just by observing at higher frequencies.

  • And then of course, world domination is not enough for us,

  • we also want to go into space.

  • If we could put a space based radio telescope

  • in an orbit around the Earth,

  • it would sweep out even more of that virtual mirror

  • and do it much more quickly.

  • Amanda Hallberg Greenwell:

  • We only have time for a couple more.

  • Let's go right here.

  • Tom Costello, NBC News: Hello, Tom from NBC news,

  • congratulations for all of you.

  • I have a question for Sera or Avery.

  • Both of you being such devoted scientists

  • and having devoted your lives to this,

  • I'm wondering what are your thoughts about Einstein,

  • who predicted much of this so long ago.

  • I wonder what your thoughts are about his genius today

  • and what you verified.

  • Sera Markoff: Well, I do spend time thinking about how it is

  • that somebody could have sat down in a patent office

  • a hundred-something years ago

  • and come up with a theory that has turned into something.

  • I mean, it is great that we can see it

  • verified with black holes,

  • but in fact we use this everyday for satellite communication.

  • It's a very integral part of our understanding of the universe.

  • But to me, I feel like there are bigger mysteries afoot.

  • I'm fascinated by Einstein

  • and that level of understanding in the universe.

  • It doesn't happen in isolation, of course, there were many

  • other people also thinking that fed into this.

  • But I'm fascinated by the fact

  • that we're now at the threshold of understanding black holes

  • as maybe the best clues about quantum gravity,

  • and what's going on. How does gravity actually work?

  • Is this some emergent process coming out of space-time?

  • What is space-time?

  • I think there is a lot more, it is just the beginning for me.

  • Avery Broderick: Sometimes the math looks ugly but really,

  • there is a strong aesthetic in theoretical physics generally,

  • and the Einstein equations are beautiful.

  • So often in my experience, nature wants to be beautiful

  • and that's one of the striking elements

  • about the Einstein equations,

  • about Einstein's description of gravity

  • is it is fundamentally

  • one of the most beautiful series theories we have.

  • For that reason alone,

  • and the long history of Einstein being proven right here,

  • I suppose we are not terribly surprised.

  • But I can't, I can't lie to you,

  • the most exciting thing we could possibly do

  • would be to supplant Einstein,

  • to find that in this extreme gravitational laboratory

  • that there is something a little new.

  • And as Sera pointed out,

  • mysteries abound around black holes.

  • And we do know that there must be something more.

  • The problem of quantum gravity remains unsolved

  • with the current tools that we have and black holes

  • are one of the places to look for answers.

  • Amanda Hallberg Greenwell: Okay. Right here.

  • Michael Greshko, National Geographic: Hi,

  • Michael Greshko, National Geographic.

  • Shep, you mentioned seeing the unseeable

  • with regards to black holes, but I want to talk about

  • another aspect of our universe, dark matter.

  • Avery, you co-authored a paper in 2017,

  • pointing out that M87 in particular

  • with the event horizon telescope

  • would be a unique probe into dark matter,

  • the degree to which it annihilates its interactions

  • with other patterns.

  • Can you say anything at this point

  • about how this measurement changes or constrains

  • what we know about dark matter?

  • Avery Broderick: The quick answer is not yet.

  • We have been very focused on making the first interpretation

  • of this groundbreaking image,

  • so we have not yet gotten to that particular topic.

  • Amanda Hallberg Greenwell: Thank you all for attending,

  • if you have further questions,

  • staff from the National Science Foundation

  • are here to help, also you have an email address

  • inside your press packets for any follow-up questions,

  • thank you for joining us today, this concludes our live stream.

  • [Applause]

Amanda Hallberg Greenwell: Okay.

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National Science Foundation/EHT Press Conference Revealing First Image of Black Hole

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    李京穎 に公開 2019 年 05 月 08 日
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