(ambient music) - [Narrator] Black holes,
where time and space converge under gravity's immutable power. These extremes of nature,
once considered improbable, are now giving up their secret. In fact, scientists have been able to imagine the impossible, the black hole at the
center of our galaxy. We can now peer into the abyss. (dramatic upbeat music) (spacecraft whooshing) (satellite whooshing) (rocket rumbling) (particles hissing) (graphic whooshing) (graphic whooshing) (dramatic music) The con
cept of black
holes was first proposed by the German astronomer and
physicist Karl Schwarzschild, barely a year after Albert
Einstein had published his works on the field equations
of gravitation in 1915. Schwarzschild wrote to Einstein
from the German trenches of the First World War, detailing
his mathematical results of his gravitational equations. Sadly, the brilliant scientist
later succumbed to a skin disease he contracted in the
trenches at the age of 42. The existence of these so-called
f
rozen stars was written about and debated for 50 years. In 1967, physicist John
Wheeler coined the term black hole to describe
these impossible objects and the conditions that would create them. New Zealander Roy Kerr
advanced the concept by publishing a solution to the equations which would require that black hole spin, like all other astronomical bodies. Then Stephen Hawking and Roger Penrose theorized that black holes
could emit radiation, now called Hawking radiation. The theory; if a black
hole
had no material to absorb and grow, then a black
hole could evaporate, effectively shrink, and die. All scientists had to do
was find one to study. Quasars, the tremendously
bright distant objects, were factored in as a strong
case for black hole accretion, the only imaginable energy source capable of such incredible luminosity. In 1964 astronomers discovered
one of the brightest X-ray sources in the sky, in the constellation Cygnus,
and labeled Cygnus X-1. The powerful source didn't coinci
de with any bright optical
(rumbling) or radio source, leaving
it in the mystery basket of observations. Before long, with advancements
in computers and space-based telescopes like Hubble,
black holes were eventually detected, or their effect on
their surrounds were detected, as black holes, by their
nature, can't be seen. - Black holes are these
incredibly fascinating but mysterious objects, we
know they sit at the hearts of galaxies, and they drive
how those galaxies grow, and how those galaxi
es die. They swallow gas and stars up. They're also these incredibly
enigmatic and mysterious objects that live at the
boundary between our two great theories of physics; general relativity, which describes gravity,
and quantum mechanics, which describes the smallest
things in the world. - Black holes are
literally gravity run amok, they are purely gravitational
objects predicted by Einstein's theory
of general relativity. And their most notable
and terrifying feature is that things go in and
th
ey never come back out. - Wonder comes to my mind first. Such objects were never expected to exist in nature until very recently. As a matter of fact, I
was a complete skeptic about black holes as
recently as 20 years ago. - Black holes are places
where Einstein's theory of general relativity is the whole story, not merely a perturbation
on top of Newton's theory, which explains the dynamics of
planets in our solar system. As a result, black holes
provide a unique environment in which to probe g
eneral
relativity, specifically, and strong gravity, generally, and its implications across the cosmos. - If you want to make a test
of the fundamental theories of the universe, you want
to go to the most extreme laboratories in the universe,
and a black hole is that. - Seeing a black hole
actually allows us to not only know they exist, and not only know an event horizon exists, it also allows us to test some
of the very basic predictions of the theory of general
relativity of Albert Einstein, w
hich really describes space and time in its completeness, and that
has never been tested before. - If you like Einstein's
theory of gravity, then black holes are, you know, one of the most interesting
examples of this theory, and this is my role within this project, I am a theorist, I work with, you know, equations and simulations,
and my role is to try and understand whether
the image that we produce corresponds to the predictions
of Einstein's theory, or maybe to something else. - From the phy
sics side I find that more an interesting
question, that this is basically some kind of rent or
terror, maybe, in space time, and a place where we don't
understand the physics and have a lot of serious questions
about information theory. - I was very excited the first
time I saw the first image. For a long time this
was purely theoretical. We were predicting that we
would see certain features in the image, but we didn't
really know was it really there, and now we know. And it was exciting that
a
ll of that uncertainty collapsed in that moment. (dramatic music) - So as the magnetized gas is
falling onto the black hole, it heats up, and therefore
generates the light that we then see. Now, from our daily experience,
we expect that light travels on straight paths and
straight trajectories, we call them rays. Here, the situation is very different, we have a black hole sitting right there. So what the black hole is doing, it is deflecting and bending
the light rays away from the straight path
s that we
understand in our daily life. (particles fizzing) And in fact, it can be so strong that we can see things that
are behind the black hole that we thought are obstructed by it, just because the black hole
is bending the light rays into our line of sight. (dramatic music) - [Narrator] Scientists began running simulations on supercomputers. Multiple computational
models were visualized to better understand what they might find in the data collected
from their observations. - After we compu
ted
the radiative signature of our simulations we have to compare them
to the observations, and this can be imagined
as you are in a stadium during a football match,
and you have an image, and you want to figure out
if this person, or whatever is on this image, is among
the spectators in the stadium, so what you do is, you take
this image and try to match it with all the 60,000
spectators in the stadium, and you do this while you
rotate it, you scale it, you increase the contrast, and
you try to
figure out first what is on your image; is it a person, is it a cat, or whatever? And try to match this to the spectators. And this seems trivial, but it's not. It's a highly computational,
demanding process. So we need a super computer,
which we have in Frankfurt, and we developed a
so-called genetic algorithm, which is a very smart way
running through these images and try to adjust them. And this takes roughly a month. And after this calculation time we have maybe 10 of those
spectators which
match your image. And this is very similar
to what we do in the EHD. So we try to compare and
match our observations with the theoretical predictions. - So what is most surprising
of this experience is that we managed to get a
very good image the first time we tried to synchronize
all of these telescope at the same time. It is not so surprising
that we obtained the image that we had predicted through simulations, because while we believe
our simulations are correct, and because we believe that
the theory of Einstein's general
relativity is the correct one. (dramatic music) - In 2019, they achieved their result, an image of the shadow
of a massive black hole in the distant M87 galaxy. It was a world first achievement celebrated around the globe. - I think we had been extremely lucky. I'd expected that we have
to work for years and years through many observations
until we get a final image. And then we look at our first
source and we see that ring, we see the event horizon,
and we see t
hat shadow, that dark region, and
you know immediately, we are looking at an event horizon, at a black hole from all
sides at once in this thing, we see at a region where time stops. This is very different
part of the universe that we're seeing for the very first time. - We want you to take an
image of a black hole. And the problem with black holes is that they are very small. So you want to take a very big black hole, which unfortunately is
very far of away from us, and so you need a big telesc
ope. This telescope is a
hundred meter in diameter, but is not enough, you
want a bigger telescope, and of course it's impossible to build. But you can create a virtual telescope by joining different telescope
in different locations. And so you can build a telescope which is as big as the Earth. And in fact, that's
exactly what we've done, we joined telescope like this with telescope on the United States, and in one even in the South Pole to get a very sharp image. Actually, an image is comparab
le to seeing an orange on the moon. (dramatic music) Black holes tell you that
are regions inside them that cannot be explored. And for a physicist,
this is very disturbing and attractive at the same time because, you know, we don't like to have
doors which we cannot cross. And in particular, inside black holes, physics is even expected
to to fail completely. And so, this even adds
fascination to these objects. - The future of the project
will hopefully going towards a new understanding of more
fundamental questions in physics. If this is true, that black
holes are the extreme objects where we can study gravity, and we know that general relativity, which describes black
holes in the outer part, up to the event horizon, breaks
down at the event horizon. So the big hope is that with
more data we might be be able to study the physics
beyond general relativity. So maybe there might be
quantum physics ruling beyond the event horizon,
or the combination of quantum physics and general relativ
ity, which would be the theory
of quantum gravity, which is nonexistent at the moment, but we might learn more about this with the help of studying black holes. (people chattering) - Our experiments are like an
arctic expedition; we have to plan for months, and months,
and months in advance, gather our equipment, and then
we have this great migration of people to observatories
all around the world. We stay up all night,
we run our telescopes, and then we have this
terrible period of waiting wher
e we don't know if it's all worked. We send all of our data together, and only when it's truly combined
do we know if it's worked. And then the even harder
part begins of analyzing that data, and being very, very careful, doing all the checks and balances to know that we got it right. (dramatic music) - Data analysis, imaging black holes, and doing simulations is very exciting, it's also very difficult and
requires a lot of patience, it's a very long process, but seeing the final
product is very
satisfying. - The Event Horizon
Telescope Collaboration is this amazing group of fantastic people from all around the world,
Americans, Europeans, people from Asia, who've come together with all their technical
expertise and scientific expertise to make this image of a
ring around the black hole. (people chattering) The future of this project
is amazing, because now that we've seen what we're after,
we have so many more questions to ask about it, to
push into the regime of, can we decide, is Ei
nstein right? Can we study how gas really gets swallowed by the black hole? Can we see a giant eruption of radiation, of particles coming out of the system? So many things to do, we've
really only just begun. - Now we wanna make the first movie. Now we want to understand how spacetime rotates around the black hole. We'll do that by putting more
telescopes around the world to make our virtual lens even better. - It was a fantastic way of combining talent from different people in a way that otherw
ise
would have not been possible. In order to take this picture
you need the cooperation, the simultaneous observations, of many radio telescopes
across the planet. You need to have the
largest possible network of telescopes taking the
same image at the same time. (dramatic music) - [Narrator] New goals for
the Event Horizon Telescope were quickly set. The M87 massive black hole
is far away from earth. Scientists wanted to get a closer look, and decided to image another black hole at the center
of a
galaxy, one much closer, but also much smaller, and
shrouded in gas and dust. (dramatic music continues) - So if you try to look
into the center of galaxies it's usually blocked from
you by dust and other stuff, and the radio you can look through. Like here, today we can look through rain, you can look through clouds,
and we can look through dust. And with combining radio
telescope like this together with other telescopes in the world, you can peer right into
the center of the galaxy and se
e this black hole. (dramatic music) - The science result, it's
just one point in time, in the project, and we
are always learning more about how the instrument
works, how people work, how new theories come about. And so this is an evolution,
in my perspective. It's not just one point in time where you say,
"This is it, that's done." It always continues. - So we still have a lot
of mysteries to be solved, you know, problems to be tackled. There are still many
questions about black holes. So I wou
ld like to study
farther in the black holes. (dramatic music continues) - [Narrator] The Event
Horizon Telescope targeted the black hole in Sagittarius
A, which is the location of the center of our very
own Milky Way galaxy. - The long term future of experiments like the Event Horizon Telescope
is moving this kind of instrument into space and
starting imaging black holes from space, which improves a
lot this kind of observation, because it allows us to have
even higher angular resolution than wh
at we have now. So we will be able, maybe
in 20 years, 30 years, make a very accurate images of the event horizon of a black hole. (ethereal music) - Not only did scientists
image the black hole, they sampled the radio emissions from the surrounding hot gases giving us an audio impression;
the sounds of a black hole. (black hole whirring) (dramatic music) - So far we've been looking at the closest massive black hole, but quasars, they are
very distant from us. With gravity, we can
see the motion
of gas, and resolve the sizes of these regions, and thereby measure
then the mass precisely. So if you can do this
for many, many quasars, many distant objects, then you
can solve perhaps the riddle how massive black holes play the role in the evolution of galaxies. We now know that basically
every galaxy has at its center a massive black hole of different masses. We'd like to understand that in detail. There is, if you like, a symbiosis between these black holes and galaxies, and we need to un
derstand
that in order to understand the evolution of the universe. (eerie music) - Studying the data from
the Event Horizon Telescope continues to reveal more detail. In this case, X-ray emissions reveal magnetic lines of force through
the orbiting gas clouds. Further study of the X-ray
emissions is currently underway with a new space based X-ray observatory, the imaging X-ray polar
imagery explorer, or IXPE. (IXPE whirring) Launched in 2021, IXPE
is designed to observe extreme cosmic objects,
like pulsars, neutron stars, and black holes. This satellite is able
to study X-ray radiation which is polarized or oscillating
in a particular direction. This reveals more detail of the physics of these high temperature environments, particularly around black holes. - But there are two other
parameters that we could look at if we only had
the tools to do that, and those have to do
with the polarization, the degree of polarization,
and the position angle, the angle associated
with the polarizati
on. So by doing this mission, we're opening up two more degrees of freedom to
be able to try to understand how are the X-rays produced,
what are the models we have to be able to predict the polarization that we
will turn out to measure. So it's really exciting. Our science working
group has studied it all. We have seven different teams
studying different classes. So for example, the the radio pulsars, supernova remnants, et cetera. And so we have, we're gonna
be looking at seven different classe
s, and several
examples of those classes, so that we get a good preliminary survey of what polarization is out there. (upbeat music) (star whirring) (star exploding) - [Narrator] The extreme
environments created by black holes are an opportunity to
study many other phenomena. Neutrinos, the most abundant
particles in the universe, have almost no mass, and very
rarely interact with matter. They seem to be generated
in extreme objects like exploding stars and
the fast particle jets ejected by supe
r massive black holes. (jets hissing) Colliding black holes are
another event closely watched, as they generate gravity waves that ripple through space time and can be detected here on Earth. Another recent event
detected, was the flipping of the magnetic field
surrounding a massive black hole. The reversing polarity
caused the visual brightening of the material
surrounding the black hole, and the reduction of its X-ray emissions, during this time, the
X-ray corona disappeared, and only when the
flipped
magnetic field gained strength did the X-ray's emissions recover. Another black hole has
been observed devouring a star that wandered too close, (black hole crackling) The ejected super fast jets of material interacting with nearby dust clouds, and aiding to form planets
within the material. These singularities appear
to be an intrinsic part of both the destruction and
creation of stars and planets. While we don't have all the answers discoveries like this one set us on a path to unders
tanding more about the universe. (spacecraft whirring) (graphic whooshing)
Comments
Since we have to go off the "Playlist" to figure out which Episode Order. This is Episode 02
Am I the only one who thinks that the whole universe is like a tornado and black holes are only the bottom of the tornado, like looking down inside a tornado? Would explain gravity?
It's not space and time, it's spacetime, It,s one thing! You can't have one without having the other. Get a grip!