supermassive black holes are an incredibly destructive force they warp
incredibly destructive force they warp
incredibly destructive force they warp space-time around them and they can
space-time around them and they can
space-time around them and they can swallow even light itself they’re the
swallow even light itself they’re the
swallow even light itself they’re the ultimate exit doors to our universe and
ultimate exit doors to our universe and
ultimate exit doors to our universe and what I’d like to convince you of today
what I’d like to convince you of today
what I’d like to convince you of today is that they haven’t really deserved
is that they haven’t really deserved
is that they haven’t really deserved this sinister reputation that even
this sinister reputation that even
this sinister reputation that even though they can swallow light black
though they can swallow light black
though they can swallow light black holes at least some of the time can be
holes at least some of the time can be
holes at least some of the time can be the brightest objects in the whole
the brightest objects in the whole
the brightest objects in the whole universe and that they play an
universe and that they play an
universe and that they play an incredibly important role in shaping our
incredibly important role in shaping our
incredibly important role in shaping our cosmos the evolution of galaxies and
cosmos the evolution of galaxies and
cosmos the evolution of galaxies and allowing maybe even for the development
allowing maybe even for the development
allowing maybe even for the development of life like our own itself what is a
of life like our own itself what is a
of life like our own itself what is a black hole a black hole is actually a
black hole a black hole is actually a
black hole a black hole is actually a very very simple object any object can
very very simple object any object can
very very simple object any object can become a black hole the only difference
become a black hole the only difference
become a black hole the only difference between say our earth or our galaxy and
between say our earth or our galaxy and
between say our earth or our galaxy and a black hole is the density so if we
a black hole is the density so if we
a black hole is the density so if we collapse say our own earth our planet
collapse say our own earth our planet
collapse say our own earth our planet down into a mathematical point it
down into a mathematical point it
down into a mathematical point it becomes what we call a black hole in
becomes what we call a black hole in
becomes what we call a black hole in fact the black hole really is is this
fact the black hole really is is this
fact the black hole really is is this mathematical point at the center which
mathematical point at the center which
mathematical point at the center which we call the singularity and this point
we call the singularity and this point
we call the singularity and this point Einstein’s general theory of relativity
Einstein’s general theory of relativity
Einstein’s general theory of relativity tells us becomes the point with infinite
tells us becomes the point with infinite
tells us becomes the point with infinite density
density
density now of course quantum mechanics tells us
now of course quantum mechanics tells us
now of course quantum mechanics tells us that’s impossible and so the singularity
that’s impossible and so the singularity
that’s impossible and so the singularity is actually one of the places where our
is actually one of the places where our
is actually one of the places where our knowledge of modern physics breaks down
knowledge of modern physics breaks down
knowledge of modern physics breaks down now this isn’t really a problem because
now this isn’t really a problem because
now this isn’t really a problem because the singularity is always hidden behind
the singularity is always hidden behind
the singularity is always hidden behind what we call the event horizon and more
what we call the event horizon and more
what we call the event horizon and more of that later so any object can become a
of that later so any object can become a
of that later so any object can become a black hole can collapse into the
black hole can collapse into the
black hole can collapse into the singularity and that means our black
singularity and that means our black
singularity and that means our black holes are very very simple objects they
holes are very very simple objects they
holes are very very simple objects they just have three simple properties they
just have three simple properties they
just have three simple properties they can have a mass how much mass did fall
can have a mass how much mass did fall
can have a mass how much mass did fall into that black hole they can have a
into that black hole they can have a
into that black hole they can have a spin that means that the black hole can
spin that means that the black hole can
spin that means that the black hole can spin to some degree and then
spin to some degree and then
spin to some degree and then least in principle it can have an
least in principle it can have an
least in principle it can have an electric charge and in general and
electric charge and in general and
electric charge and in general and Astrophysical applications the kinds of
Astrophysical applications the kinds of
Astrophysical applications the kinds of things that any study we ignore the
things that any study we ignore the
things that any study we ignore the charge there’s really just the mass and
charge there’s really just the mass and
charge there’s really just the mass and the spin so why does nothing able to
the spin so why does nothing able to
the spin so why does nothing able to escape from a black hole why do things
escape from a black hole why do things
escape from a black hole why do things even like itself get stuck near a black
even like itself get stuck near a black
even like itself get stuck near a black hole well let’s take the difference to a
hole well let’s take the difference to a
hole well let’s take the difference to a normal object like our earth so I put a
normal object like our earth so I put a
normal object like our earth so I put a baseball player Babe Ruth on the surface
baseball player Babe Ruth on the surface
baseball player Babe Ruth on the surface of the earth and he can hit a ball and
of the earth and he can hit a ball and
of the earth and he can hit a ball and if he hits the ball really hard the ball
if he hits the ball really hard the ball
if he hits the ball really hard the ball will go up and then the pull of gravity
will go up and then the pull of gravity
will go up and then the pull of gravity from the earth will pull it back down to
from the earth will pull it back down to
from the earth will pull it back down to the surface now in principle if babe
the surface now in principle if babe
the surface now in principle if babe hits the ball really really hard that
hits the ball really really hard that
hits the ball really really hard that ball can escape the gravitational well
ball can escape the gravitational well
ball can escape the gravitational well of the earth and go off into infinity
of the earth and go off into infinity
of the earth and go off into infinity can escape the earth itself
can escape the earth itself
can escape the earth itself if we now collapse the earth into a
if we now collapse the earth into a
if we now collapse the earth into a black hole and put Babe Ruth right next
black hole and put Babe Ruth right next
black hole and put Babe Ruth right next to the singularity we can repeat the
to the singularity we can repeat the
to the singularity we can repeat the experiment but the difference is that no
experiment but the difference is that no
experiment but the difference is that no matter how hard he hits the ball it will
matter how hard he hits the ball it will
matter how hard he hits the ball it will never escape it will always fall into
never escape it will always fall into
never escape it will always fall into the singularity the reason for that is
the singularity the reason for that is
the singularity the reason for that is that the escape velocity near the
that the escape velocity near the
that the escape velocity near the singularity exceeds that of the speed of
singularity exceeds that of the speed of
singularity exceeds that of the speed of light
light
light and nothing can move faster than the
and nothing can move faster than the
and nothing can move faster than the speed of light so there’s no way you can
speed of light so there’s no way you can
speed of light so there’s no way you can get out of the vicinity of the black
get out of the vicinity of the black
get out of the vicinity of the black hole and the event horizon is simply the
hole and the event horizon is simply the
hole and the event horizon is simply the point where the escape velocity is
point where the escape velocity is
point where the escape velocity is exactly the speed of light so your event
exactly the speed of light so your event
exactly the speed of light so your event horizon isn’t really a surface it’s just
horizon isn’t really a surface it’s just
horizon isn’t really a surface it’s just the ultimate point of no return
the ultimate point of no return
the ultimate point of no return once you cross it no matter how fast you
once you cross it no matter how fast you
once you cross it no matter how fast you go you can never get away again and
go you can never get away again and
go you can never get away again and that’s why it’s a black hole there are
that’s why it’s a black hole there are
that’s why it’s a black hole there are also other important differences to what
also other important differences to what
also other important differences to what happens near a black hole compared to a
happens near a black hole compared to a
happens near a black hole compared to a normal object so again imagine we
normal object so again imagine we
normal object so again imagine we collapse the earth into a black hole and
collapse the earth into a black hole and
collapse the earth into a black hole and an astronaut tries to orbit it so this
an astronaut tries to orbit it so this
an astronaut tries to orbit it so this astronaut she’s trying to orbit this
astronaut she’s trying to orbit this
astronaut she’s trying to orbit this black hole and unlike around the earth
black hole and unlike around the earth
black hole and unlike around the earth where a stable orbit is perfectly
where a stable orbit is perfectly
where a stable orbit is perfectly possible around a black hole once you
possible around a black hole once you
possible around a black hole once you get close enough there is no more stable
get close enough there is no more stable
get close enough there is no more stable orbit and so she’ll have a inevitably
orbit and so she’ll have a inevitably
orbit and so she’ll have a inevitably fall into the black hole and it’s worse
fall into the black hole and it’s worse
fall into the black hole and it’s worse than that because the tidal force is the
than that because the tidal force is the
than that because the tidal force is the gravitational field near the black hole
gravitational field near the black hole
gravitational field near the black hole is so strong
is so strong
is so strong that the force of gravity on her head is
that the force of gravity on her head is
that the force of gravity on her head is not as strong as the force of gravity on
not as strong as the force of gravity on
not as strong as the force of gravity on her feet as she falls towards the black
her feet as she falls towards the black
her feet as she falls towards the black hole and so as she falls into the black
hole and so as she falls into the black
hole and so as she falls into the black hole she’ll be stretched and torn apart
hole she’ll be stretched and torn apart
hole she’ll be stretched and torn apart further and further and the technical
further and further and the technical
further and further and the technical name for this process is
name for this process is
name for this process is spaghettification so what kind of black
spaghettification so what kind of black
spaghettification so what kind of black hole would we actually get if we took
hole would we actually get if we took
hole would we actually get if we took the earth and collapsed it into a black
the earth and collapsed it into a black
the earth and collapsed it into a black hole so your office you know we know
hole so your office you know we know
hole so your office you know we know it’s kind of big but if we turn it into
it’s kind of big but if we turn it into
it’s kind of big but if we turn it into a black hole how big do you think it
a black hole how big do you think it
a black hole how big do you think it would get well shrinking keeps shrinking
would get well shrinking keeps shrinking
would get well shrinking keeps shrinking the animators worked on this for quite a
the animators worked on this for quite a
the animators worked on this for quite a while and it keeps shrinking keep
while and it keeps shrinking keep
while and it keeps shrinking keep shrinking well nine millimeters so a
shrinking well nine millimeters so a
shrinking well nine millimeters so a black hole with the mass of the Earth
black hole with the mass of the Earth
black hole with the mass of the Earth it’s just about nine millimeters across
it’s just about nine millimeters across
it’s just about nine millimeters across if we take the Sun instead and collapse
if we take the Sun instead and collapse
if we take the Sun instead and collapse the Sun into a black hole we get
the Sun into a black hole we get
the Sun into a black hole we get something that’s about three kilometers
something that’s about three kilometers
something that’s about three kilometers across and so our Milky Way galaxy is
across and so our Milky Way galaxy is
across and so our Milky Way galaxy is full of these stellar-mass black holes
full of these stellar-mass black holes
full of these stellar-mass black holes that have maybe a few solar masses these
that have maybe a few solar masses these
that have maybe a few solar masses these are the the corpses of massive stars
are the the corpses of massive stars
are the the corpses of massive stars that died and supernovae and if the
that died and supernovae and if the
that died and supernovae and if the cannibalizing a companion star they
cannibalizing a companion star they
cannibalizing a companion star they light up in x-rays and gamma rays and we
light up in x-rays and gamma rays and we
light up in x-rays and gamma rays and we see them in the sky and we can study
see them in the sky and we can study
see them in the sky and we can study them but that’s kind of still too small
them but that’s kind of still too small
them but that’s kind of still too small for me so I study supermassive black
for me so I study supermassive black
for me so I study supermassive black holes that live at the Centers of
holes that live at the Centers of
holes that live at the Centers of galaxies so this is now a supermassive
galaxies so this is now a supermassive
galaxies so this is now a supermassive black hole and it’s got a mass of four
black hole and it’s got a mass of four
black hole and it’s got a mass of four million times that of our Sun and I
million times that of our Sun and I
million times that of our Sun and I chose that number specifically it’s an
chose that number specifically it’s an
chose that number specifically it’s an oddly specific number and I’ll get back
oddly specific number and I’ll get back
oddly specific number and I’ll get back to why I picked that number in a second
to why I picked that number in a second
to why I picked that number in a second so this black hole now has a radius of
so this black hole now has a radius of
so this black hole now has a radius of 0.08 astronomical units an astronomical
0.08 astronomical units an astronomical
0.08 astronomical units an astronomical unit is simply the distance from the
unit is simply the distance from the
unit is simply the distance from the earth to the Sun so now we have a kind
earth to the Sun so now we have a kind
earth to the Sun so now we have a kind of sizable object but actually the
of sizable object but actually the
of sizable object but actually the universe makes even bigger monsters so
universe makes even bigger monsters so
universe makes even bigger monsters so the largest black holes the most massive
the largest black holes the most massive
the largest black holes the most massive black holes that we know are about ten
black holes that we know are about ten
black holes that we know are about ten billion solar masses so these are the
billion solar masses so these are the
billion solar masses so these are the truly supermassive black holes and I’ve
truly supermassive black holes and I’ve
truly supermassive black holes and I’ve indicated here the orbit of Pluto so
indicated here the orbit of Pluto so
indicated here the orbit of Pluto so that means we could fit our entire solar
that means we could fit our entire solar
that means we could fit our entire solar system comfortably inside this
system comfortably inside this
system comfortably inside this supermassive black hole so as I said we
supermassive black hole so as I said we
supermassive black hole so as I said we think that most galaxies maybe or
think that most galaxies maybe or
think that most galaxies maybe or galaxies contain a supermassive black
galaxies contain a supermassive black
galaxies contain a supermassive black hole
hole
hole the center and in fact we’re not even
the center and in fact we’re not even
the center and in fact we’re not even sure what was there first the black hole
sure what was there first the black hole
sure what was there first the black hole of the galaxy it’s of one of these
of the galaxy it’s of one of these
of the galaxy it’s of one of these chicken-and-egg problems and there’s one
chicken-and-egg problems and there’s one
chicken-and-egg problems and there’s one galaxy that has a four million solar
galaxy that has a four million solar
galaxy that has a four million solar mass black hole very specifically and
mass black hole very specifically and
mass black hole very specifically and that’s this galaxy which I think you
that’s this galaxy which I think you
that’s this galaxy which I think you will recognize it’s our own it’s the
will recognize it’s our own it’s the
will recognize it’s our own it’s the Milky Way so the center of the Milky Way
Milky Way so the center of the Milky Way
Milky Way so the center of the Milky Way lurks a supermassive black hole in fact
lurks a supermassive black hole in fact
lurks a supermassive black hole in fact if we zoom in what you see here is a as
if we zoom in what you see here is a as
if we zoom in what you see here is a as a reconstruction or a model of the
a reconstruction or a model of the
a reconstruction or a model of the motions of a couple of dozen stars or so
motions of a couple of dozen stars or so
motions of a couple of dozen stars or so at the center of the Milky Way and you
at the center of the Milky Way and you
at the center of the Milky Way and you can see they all orbit this empty spot
can see they all orbit this empty spot
can see they all orbit this empty spot in space and so using actually just
in space and so using actually just
in space and so using actually just Newton’s gravity you don’t even need
Newton’s gravity you don’t even need
Newton’s gravity you don’t even need relativity for this you can work out how
relativity for this you can work out how
relativity for this you can work out how much mass don’t need to put at this
much mass don’t need to put at this
much mass don’t need to put at this empty spot to fling around these stars
empty spot to fling around these stars
empty spot to fling around these stars like crazy and it turns out that number
like crazy and it turns out that number
like crazy and it turns out that number is exactly four million solar masses and
is exactly four million solar masses and
is exactly four million solar masses and so this is work that was done by
so this is work that was done by
so this is work that was done by astronomers in California and in Germany
astronomers in California and in Germany
astronomers in California and in Germany and you know that’s is our supermassive
and you know that’s is our supermassive
and you know that’s is our supermassive black hole and this is why we know it’s
black hole and this is why we know it’s
black hole and this is why we know it’s there now an important point here is
there now an important point here is
there now an important point here is that this is maybe a few dozen maybe a
that this is maybe a few dozen maybe a
that this is maybe a few dozen maybe a few hundred stars that really feel the
few hundred stars that really feel the
few hundred stars that really feel the gravitational pull of the black hole now
gravitational pull of the black hole now
gravitational pull of the black hole now a milky way has something like a hundred
a milky way has something like a hundred
a milky way has something like a hundred billion stars including our own Sun and
billion stars including our own Sun and
billion stars including our own Sun and so virtually none of the stars in the
so virtually none of the stars in the
so virtually none of the stars in the Milky Way
Milky Way
Milky Way really feel the gravitational pull of
really feel the gravitational pull of
really feel the gravitational pull of the central black hole this is an
the central black hole this is an
the central black hole this is an important point to remember we’re not
important point to remember we’re not
important point to remember we’re not about to fall in to the Milky Way black
about to fall in to the Milky Way black
about to fall in to the Milky Way black hole now the Milky Way black hole
hole now the Milky Way black hole
hole now the Milky Way black hole currently is quiescent it’s sort of
currently is quiescent it’s sort of
currently is quiescent it’s sort of flaring on occasion but it doesn’t
flaring on occasion but it doesn’t
flaring on occasion but it doesn’t really do very much but when
really do very much but when
really do very much but when supermassive black holes feed they light
supermassive black holes feed they light
supermassive black holes feed they light up and they become a quasar as we call
up and they become a quasar as we call
up and they become a quasar as we call them quasars
them quasars
them quasars he’s a artists concept of what this
he’s a artists concept of what this
he’s a artists concept of what this might look like we can’t really image
might look like we can’t really image
might look like we can’t really image this directly yet but we believe happens
this directly yet but we believe happens
this directly yet but we believe happens is that the material starts spiraling
is that the material starts spiraling
is that the material starts spiraling into the black hole and forms an
into the black hole and forms an
into the black hole and forms an accretion disk that accretion disk gets
accretion disk that accretion disk gets
accretion disk that accretion disk gets enormously hot and radiates light and
enormously hot and radiates light and
enormously hot and radiates light and you might form relativistic Jets that
you might form relativistic Jets that
you might form relativistic Jets that come out at the poles and so a
come out at the poles and so a
come out at the poles and so a supermassive black hole when it turns
supermassive black hole when it turns
supermassive black hole when it turns into a quasar becomes enormously bright
into a quasar becomes enormously bright
into a quasar becomes enormously bright so here’s a real image of a galaxy
so here’s a real image of a galaxy
so here’s a real image of a galaxy merger galaxy collision where we now
merger galaxy collision where we now
merger galaxy collision where we now have a central
have a central
have a central supermassive black hole the black holes
supermassive black hole the black holes
supermassive black hole the black holes of merge and you can see the star like
of merge and you can see the star like
of merge and you can see the star like object at the center of this merging
object at the center of this merging
object at the center of this merging galaxies and that’s the quasar and so in
galaxies and that’s the quasar and so in
galaxies and that’s the quasar and so in this galaxy murder is something like a
this galaxy murder is something like a
this galaxy murder is something like a hundred billion stars put together doing
hundred billion stars put together doing
hundred billion stars put together doing nuclear fusion you know the holy grail
nuclear fusion you know the holy grail
nuclear fusion you know the holy grail of energy policy 100 billion stars doing
of energy policy 100 billion stars doing
of energy policy 100 billion stars doing nuclear fusion and that’s supermassive
nuclear fusion and that’s supermassive
nuclear fusion and that’s supermassive black hole at the center it’s about a
black hole at the center it’s about a
black hole at the center it’s about a billion solar masses or so is putting
billion solar masses or so is putting
billion solar masses or so is putting out more energy than a hundred billion
out more energy than a hundred billion
out more energy than a hundred billion stars put together and all that from a
stars put together and all that from a
stars put together and all that from a volume may be the size of our solar
volume may be the size of our solar
volume may be the size of our solar system and the reason for that is that
system and the reason for that is that
system and the reason for that is that deep gravitational wells black holes are
deep gravitational wells black holes are
deep gravitational wells black holes are the most efficient engines in the
the most efficient engines in the
the most efficient engines in the universe so you all know Einstein’s
universe so you all know Einstein’s
universe so you all know Einstein’s famous equals MC squared so mass is the
famous equals MC squared so mass is the
famous equals MC squared so mass is the same as energy but C squares have very
same as energy but C squares have very
same as energy but C squares have very very large numbers so a little mass gets
very large numbers so a little mass gets
very large numbers so a little mass gets you a lot of energy this quasar this
you a lot of energy this quasar this
you a lot of energy this quasar this black hole is currently feeding
black hole is currently feeding
black hole is currently feeding on something like a solar mass per year
on something like a solar mass per year
on something like a solar mass per year and turning a good fraction of that
and turning a good fraction of that
and turning a good fraction of that straight back into energy there were
straight back into energy there were
straight back into energy there were solar mass appears a bit of a esoteric
solar mass appears a bit of a esoteric
solar mass appears a bit of a esoteric quantity you probably don’t use it in
quantity you probably don’t use it in
quantity you probably don’t use it in your daily life and so one evening over
your daily life and so one evening over
your daily life and so one evening over some drinks we try to come up with a
some drinks we try to come up with a
some drinks we try to come up with a with a more tangible number what a solar
with a more tangible number what a solar
with a more tangible number what a solar mass per year is and it turns out to be
mass per year is and it turns out to be
mass per year is and it turns out to be almost exactly one moon per second so
almost exactly one moon per second so
almost exactly one moon per second so this quasar is turning one moon one
this quasar is turning one moon one
this quasar is turning one moon one earth moon per second into pure energy
earth moon per second into pure energy
earth moon per second into pure energy and that’s why black holes are the
and that’s why black holes are the
and that’s why black holes are the brightest things in the universe so what
brightest things in the universe so what
brightest things in the universe so what does all this energy liberated by black
does all this energy liberated by black
does all this energy liberated by black holes do is it just you know pretty do
holes do is it just you know pretty do
holes do is it just you know pretty do we see it in the sky do we get to study
we see it in the sky do we get to study
we see it in the sky do we get to study it and admire it or does it have a
it and admire it or does it have a
it and admire it or does it have a deeper function does it have a deeper
deeper function does it have a deeper
deeper function does it have a deeper role in shaping our cosmos and many
role in shaping our cosmos and many
role in shaping our cosmos and many astrophysicists including me believe the
astrophysicists including me believe the
astrophysicists including me believe the answer to that is yes it’s actually
answer to that is yes it’s actually
answer to that is yes it’s actually really important to shaping our universe
really important to shaping our universe
really important to shaping our universe our Milky Way but to explain to you why
our Milky Way but to explain to you why
our Milky Way but to explain to you why this is I have to give you a brief
this is I have to give you a brief
this is I have to give you a brief introduction to galaxy formation galaxy
introduction to galaxy formation galaxy
introduction to galaxy formation galaxy formation 101 if you will so as you all
formation 101 if you will so as you all
formation 101 if you will so as you all know the universe started with a big
know the universe started with a big
know the universe started with a big bang and right after the Big Bang all we
bang and right after the Big Bang all we
bang and right after the Big Bang all we had were tiny little quantum
had were tiny little quantum
had were tiny little quantum fluctuations which were
fluctuations which were
fluctuations which were vastly enlarged by this epoch we call
vastly enlarged by this epoch we call
vastly enlarged by this epoch we call inflation and when that was over the
inflation and when that was over the
inflation and when that was over the universe developed further simply under
universe developed further simply under
universe developed further simply under the influence of gravity and so what I’m
the influence of gravity and so what I’m
the influence of gravity and so what I’m showing you here is a simulation done by
showing you here is a simulation done by
showing you here is a simulation done by scientists at MIT and other institutions
scientists at MIT and other institutions
scientists at MIT and other institutions of you know all the physics all the
of you know all the physics all the
of you know all the physics all the knowledge we have our galaxy formation
knowledge we have our galaxy formation
knowledge we have our galaxy formation you can see these structures start
you can see these structures start
you can see these structures start building so these are these tiny quantum
building so these are these tiny quantum
building so these are these tiny quantum fluctuations that blew up and now
fluctuations that blew up and now
fluctuations that blew up and now collapse under gravity and so they form
collapse under gravity and so they form
collapse under gravity and so they form halos of dark matter they become larger
halos of dark matter they become larger
halos of dark matter they become larger and larger and they collapse and then
and larger and they collapse and then
and larger and they collapse and then the gas the normal matter streams into
the gas the normal matter streams into
the gas the normal matter streams into these halos and when the gas gets to the
these halos and when the gas gets to the
these halos and when the gas gets to the center and it cools down and gets denser
center and it cools down and gets denser
center and it cools down and gets denser and denser it starts to form stars it
and denser it starts to form stars it
and denser it starts to form stars it makes stars and of course around stars
makes stars and of course around stars
makes stars and of course around stars we make planets like our own this is
we make planets like our own this is
we make planets like our own this is where we like to live
where we like to live
where we like to live the problem is in simulations like this
the problem is in simulations like this
the problem is in simulations like this if you just let them proceed your
if you just let them proceed your
if you just let them proceed your collapse under gravity the galaxies get
collapse under gravity the galaxies get
collapse under gravity the galaxies get too big there’s too much star formation
too big there’s too much star formation
too big there’s too much star formation and so what we need is a thermostat and
and so what we need is a thermostat and
and so what we need is a thermostat and you start to see it acting here we need
you start to see it acting here we need
you start to see it acting here we need a way to dial down the cooling and the
a way to dial down the cooling and the
a way to dial down the cooling and the star formation and we believe the
star formation and we believe the
star formation and we believe the mechanism that does that are the
mechanism that does that are the
mechanism that does that are the supermassive black holes so physicists
supermassive black holes so physicists
supermassive black holes so physicists love slightly pretentious names for
love slightly pretentious names for
love slightly pretentious names for problems so this runaway star formation
problems so this runaway star formation
problems so this runaway star formation runaway galaxy formation we call the
runaway galaxy formation we call the
runaway galaxy formation we call the over cooling problem or the over cooling
over cooling problem or the over cooling
over cooling problem or the over cooling catastrophe and we believe that black
catastrophe and we believe that black
catastrophe and we believe that black holes solve this problem you see these
holes solve this problem you see these
holes solve this problem you see these explosions these are the supermassive
explosions these are the supermassive
explosions these are the supermassive black holes going off putting all this
black holes going off putting all this
black holes going off putting all this energy back out stopping the gas from
energy back out stopping the gas from
energy back out stopping the gas from cooling throwing it back out of the
cooling throwing it back out of the
cooling throwing it back out of the galaxy and so regulating the formation
galaxy and so regulating the formation
galaxy and so regulating the formation and evolution of galaxies including
and evolution of galaxies including
and evolution of galaxies including galaxies like our own Milky Way so I’m
galaxies like our own Milky Way so I’m
galaxies like our own Milky Way so I’m an observational astrophysicist I use
an observational astrophysicist I use
an observational astrophysicist I use data I observe the universe and I try to
data I observe the universe and I try to
data I observe the universe and I try to find evidence for this process for this
find evidence for this process for this
find evidence for this process for this regulatory role of supermassive black
regulatory role of supermassive black
regulatory role of supermassive black holes and so what I’m showing you here
holes and so what I’m showing you here
holes and so what I’m showing you here is the deepest image of the x-ray sky
is the deepest image of the x-ray sky
is the deepest image of the x-ray sky ever taken it’s actually a tiny tiny
ever taken it’s actually a tiny tiny
ever taken it’s actually a tiny tiny patch on the sky but it was taken by the
patch on the sky but it was taken by the
patch on the sky but it was taken by the Chandra x-ray Observatory which is a bus
Chandra x-ray Observatory which is a bus
Chandra x-ray Observatory which is a bus is x-ray telescope in space it’s
is x-ray telescope in space it’s
is x-ray telescope in space it’s launched by the space shuttle and it’s
launched by the space shuttle and it’s
launched by the space shuttle and it’s stared at this tiny patch of the sky for
stared at this tiny patch of the sky for
stared at this tiny patch of the sky for more than a month to record all these
more than a month to record all these
more than a month to record all these little points that you see all these
little points that you see all these
little points that you see all these little light sources so these are x-ray
little light sources so these are x-ray
little light sources so these are x-ray sources and almost all these points that
sources and almost all these points that
sources and almost all these points that you see here are black holes feeding on
you see here are black holes feeding on
you see here are black holes feeding on materials so you see the the final death
materials so you see the the final death
materials so you see the the final death scream of the material as it falls into
scream of the material as it falls into
scream of the material as it falls into a black hole and some of these black
a black hole and some of these black
a black hole and some of these black holes active black holes are in our
holes active black holes are in our
holes active black holes are in our neighborhood they’re near to us and some
neighborhood they’re near to us and some
neighborhood they’re near to us and some of these are at the other end of the
of these are at the other end of the
of these are at the other end of the universe so what you’re seeing here
universe so what you’re seeing here
universe so what you’re seeing here really is a full record of the growth
really is a full record of the growth
really is a full record of the growth the formation and growth of black holes
the formation and growth of black holes
the formation and growth of black holes together with their host galaxies from
together with their host galaxies from
together with their host galaxies from the beginnings of the universe until
the beginnings of the universe until
the beginnings of the universe until today and I want to understand how this
today and I want to understand how this
today and I want to understand how this process works so the kind of research we
process works so the kind of research we
process works so the kind of research we do the kind of new approaches that we
do the kind of new approaches that we
do the kind of new approaches that we take to this problem include things like
take to this problem include things like
take to this problem include things like trying to understand the full lifecycle
trying to understand the full lifecycle
trying to understand the full lifecycle of black holes so galaxies are very
of black holes so galaxies are very
of black holes so galaxies are very large objects the Milky Way has a
large objects the Milky Way has a
large objects the Milky Way has a characteristic time scale so if you poke
characteristic time scale so if you poke
characteristic time scale so if you poke the Milky Way it will respond on a time
the Milky Way it will respond on a time
the Milky Way it will respond on a time scale of about a hundred million years
scale of about a hundred million years
scale of about a hundred million years which to me is an astrophysicist is
which to me is an astrophysicist is
which to me is an astrophysicist is actually kind of short but if you think
actually kind of short but if you think
actually kind of short but if you think about it that’s longer than the time
about it that’s longer than the time
about it that’s longer than the time since the dinosaurs died out so galaxies
since the dinosaurs died out so galaxies
since the dinosaurs died out so galaxies are kind of slow-moving things but black
are kind of slow-moving things but black
are kind of slow-moving things but black holes aren’t black holes may be acting
holes aren’t black holes may be acting
holes aren’t black holes may be acting on much shorter time scales and so I’m
on much shorter time scales and so I’m
on much shorter time scales and so I’m showing you here is a work in progress
showing you here is a work in progress
showing you here is a work in progress that my students and postdocs and I at
that my students and postdocs and I at
that my students and postdocs and I at ETH are doing these are Hubble images of
ETH are doing these are Hubble images of
ETH are doing these are Hubble images of merging galaxies what you see in green
merging galaxies what you see in green
merging galaxies what you see in green here is gas that’s being lit up by an
here is gas that’s being lit up by an
here is gas that’s being lit up by an active black hole by a quasar so imagine
active black hole by a quasar so imagine
active black hole by a quasar so imagine you have a fog bank at night and you
you have a fog bank at night and you
you have a fog bank at night and you take a flashlight and you shine it on
take a flashlight and you shine it on
take a flashlight and you shine it on that fog bank now you see the fog this
that fog bank now you see the fog this
that fog bank now you see the fog this is essentially the same idea except the
is essentially the same idea except the
is essentially the same idea except the flashlight is a supermassive black hole
flashlight is a supermassive black hole
flashlight is a supermassive black hole and the fog bank is a gas cloud the size
and the fog bank is a gas cloud the size
and the fog bank is a gas cloud the size of a galaxy and because it’s so large
of a galaxy and because it’s so large
of a galaxy and because it’s so large it’s tens or hundreds of thousands of
it’s tens or hundreds of thousands of
it’s tens or hundreds of thousands of light years across that means the light
light years across that means the light
light years across that means the light from the quasar took an awfully long
from the quasar took an awfully long
from the quasar took an awfully long time to get to the cloud and light it up
time to get to the cloud and light it up
time to get to the cloud and light it up which means we now have a record
which means we now have a record
which means we now have a record of the accretion history of the shining
of the accretion history of the shining
of the accretion history of the shining of the energy output of the black hole
of the energy output of the black hole
of the energy output of the black hole over time over the last ten two hundred
over time over the last ten two hundred
over time over the last ten two hundred thousand years and that’s really
thousand years and that’s really
thousand years and that’s really exciting and so this is starting to
exciting and so this is starting to
exciting and so this is starting to allow us to reconstruct the accretion
allow us to reconstruct the accretion
allow us to reconstruct the accretion history the the flickering the
history the the flickering the
history the the flickering the variability of supermassive black holes
variability of supermassive black holes
variability of supermassive black holes and timescales
and timescales
and timescales beyond that of a PhD thesis and so what
beyond that of a PhD thesis and so what
beyond that of a PhD thesis and so what we’re hoping to see in the end there’s
we’re hoping to see in the end there’s
we’re hoping to see in the end there’s something like this behaviour in this
something like this behaviour in this
something like this behaviour in this case I’m showing you as data from a star
case I’m showing you as data from a star
case I’m showing you as data from a star and the star gets brighter and fainter
and the star gets brighter and fainter
and the star gets brighter and fainter it goes up and down and up and down you
it goes up and down and up and down you
it goes up and down and up and down you can see the echoes of these activity
can see the echoes of these activity
can see the echoes of these activity pulses moving out across the gas and
pulses moving out across the gas and
pulses moving out across the gas and dust surrounding the stars and so we’re
dust surrounding the stars and so we’re
dust surrounding the stars and so we’re trying to do something like that but for
trying to do something like that but for
trying to do something like that but for entire galaxies and where the source
entire galaxies and where the source
entire galaxies and where the source isn’t just a star but a quasar so I hope
isn’t just a star but a quasar so I hope
isn’t just a star but a quasar so I hope I’ve convinced you that supermassive
I’ve convinced you that supermassive
I’ve convinced you that supermassive black holes aren’t just you know a dark
black holes aren’t just you know a dark
black holes aren’t just you know a dark force of destruction but that they’re
force of destruction but that they’re
force of destruction but that they’re actually really important that they’re
actually really important that they’re
actually really important that they’re the brightest things in the universe and
the brightest things in the universe and
the brightest things in the universe and they’re essential to shaping our
they’re essential to shaping our
they’re essential to shaping our universe what you’re seeing here is what
universe what you’re seeing here is what
universe what you’re seeing here is what it would look like in full gr if we fell
it would look like in full gr if we fell
it would look like in full gr if we fell into the black hole and near the center
into the black hole and near the center
into the black hole and near the center of the Milky Way and you can see these
of the Milky Way and you can see these
of the Milky Way and you can see these distortions as the universe recedes from
distortions as the universe recedes from
distortions as the universe recedes from us and I believe at this point we’ve
us and I believe at this point we’ve
us and I believe at this point we’ve already passed the event horizon so
already passed the event horizon so
already passed the event horizon so there’s no way back we’re already inside
there’s no way back we’re already inside
there’s no way back we’re already inside we’re already doomed and so now there’s
we’re already doomed and so now there’s
we’re already doomed and so now there’s really nothing left to do but wait until
really nothing left to do but wait until
really nothing left to do but wait until we hit the singularity which will be any
we hit the singularity which will be any
we hit the singularity which will be any moment now that’s it thank you very much
moment now that’s it thank you very much
moment now that’s it thank you very much [Applause]
[Applause]
[Applause] [Music]
[Music]
[Music] you
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