All language subtitles for How the Universe Works (2023) - S11E03 - The Most Violent Event in the Universe_track3_[eng]

ROWE: You might have seen
a boxing match on TV.

Maybe you've even
seen one live.

But you have never seen
a contest like this.

Take your ringside seat to
the fight of the cosmos.

This is gonna be a wonderful
fight to witness.

But you'll want to be a few

million billion
light-years away.

It's like being punched by
the ghost of Muhammad Ali.

You don't even see it coming.

You don't even see it coming.

ROWE: Our fighters don't float
like a butterfly or sting like

a bee, but they can deliver
the ultimate knockout blow.

It is a soul-chilling,
mind-crushing amount of energy.

It's just unbelievable.

ROWE: It's a fight between
two supermassive black holes.

Forget about the world
heavyweight championships.

This is the universe's
heavyweight championships.

ROWE: Get ready
for the heavyweight

championship of the universe.

championship of the universe.

2021,
scientists detect

a gigantic rumble
deep in space,

a tsunami of
gravitational waves,

giant ripples racing
across the universe.

giant ripples racing
across the universe.

MINGARELLI: Gravitational waves
that big have to

come from a giant,
cataclysmic event.

The universe is immense
and full of very

violent events that are
happening every single day.

The universe
is a scary place.

There is violence
everywhere we look.

ROWE: The growls and roars
are clues about

the ultimate cosmic brawl,

the most violent event in
the universe.

the most violent event in
the universe.

But we don't know
where they're coming from.

SUTTER: Imagine
a storm is coming

in the middle of the night.

You can't see the storm,

you can't see the lightning,
but you can hear that rumble of

the distant thunder,
and you know that it's coming.

ROWE: This distant rumble
of gravitational waves

is like the footwork
of heavyweights

pounding the canvas
of the boxing ring.

The waves are caused
by something massive

The waves are caused
by something massive

throwing its weight around.

It's not the first time we've
detected gravitational waves.

Our experiments
have picked up

the signal of
two small stellar mass

black holes colliding.

These waves are high-pitched
and ring like a boxing bell.

The deep space growl
is a much lower frequency,

like the roar of a crowd.

like the roar of a crowd.

[crowd chanting]

MINGARELLI:
The difference in frequencies

would be even more exaggerated
than the difference

between a sparrow chirping
and the sound coming from

a blue whale underwater.

It would be orders of magnitude
more different than that.

ROWE: The low frequency
of the deep space rumble

tells us that
the waves are colossal.

MINGARELLI: Imagine throwing
a stone in the water

and watching the little
ripples come out.

and watching the little
ripples come out.

Now imagine throwing
in a boulder a billion times

more massive

and watching the huge waves
that come from that.

Those are the waves
that we're looking at.

These are more
difficult to detect,

because the waves are
so big.

One of their wavelengths is
about 15 light-years.

You could wait for 15 years

and only have one wavelength
go by the Earth.

ROWE: The waves are too big
for an earthbound detector

to pick up.

to pick up.

So, to search for the source
of these giant waves,

Chiara Mingarelli
and her team

use a detector
already in space,

something large enough
to pick up

these galactic heavyweights,

spinning dead stars
called pulsars.

MINGARELLI: Our galaxy
is awash with pulsars.

Now, they're called pulsars
because they pulsate

very regularly -- they're
like cosmic lighthouses.

ROWE: The lighthouse beams
are so regular,

ROWE: The lighthouse beams
are so regular,

you can set your watch
by them.

But when a huge gravitational
wave hits them,

the timing gets knocked out
of whack.

PLAIT: That pulsar is going to
basically rock back and forth

and that's going
to change the timing

of the pulses that
we measure from that object.

ROWE: To identify the source
of the gravitational waves,

Chiara and her team measure
the wobbles of 100 pulsars,

spread across light-years
of space.

spread across light-years
of space.

MINGARELLI: It's like a tsunami,
and the pulsars are

like the buoys on the surface
of the ocean.

And as the tsunami passes by,

we can watch
all of them moving

and shifting up and down.

So our pulsar timing array

is a gravitational wave
warning system.

ROWE: The pulsar array
has identified

the source of the tsunami
of gravitational waves.

The only thing we know
of that can make these

very long wavelength,
[deep voice] very low pitch

very long wavelength,
[deep voice] very low pitch

[normally] gravitational waves
would be the collisions

of supermassive black holes.

MINGARELLI: They're massive,
they're huge,

and they know how
to throw their weight around.

Supermassive black hole
binaries produce the loudest

gravitational waves in
the universe.

ROWE: The gravitational wave
signal revealed

something extraordinary.

MINGARELLI: It's not just
gravitational waves coming

from one black hole
binary pair.

It's actually from the cosmic

population of supermassive
black hole binaries.

population of supermassive
black hole binaries.

ROWE: Chiara and her team
think there may be

tens of thousands of
heavyweight bouts going on.

Now, the scientists want to
pick out the sound of one

single collision between two
supermassive black holes from

the background roar.

MINGARELLI:
If we were to hear

a supermassive
black hole merger,

it would sound like a very
low frequency growl.

it would sound like a very
low frequency growl.

This "ooooooh"

that would last
about 25 million years.

ROWE: To date, we haven't
witnessed two supermassive

black holes trading blows
in real time.

But we have seen events
leading up

to the championship bout.

We've watched galaxies merge.

We've seen stars explode.

We've seen so many violent
events in the universe.

But we haven't seen
this one.

It's odd if you think
about it.

We haven't seen
the biggest one.

We haven't seen
the biggest one.

We haven't seen mergers between
supermassive black holes.

ROWE: But that may be
about to change.

Chiara predicts there are
112 fighters who are

pumped up and ready
to enter the ring.

MINGARELLI: In the next
five years,

we should be able to detect
at least one

supermassive
black hole merger.

ROWE: It'll be the most violent
event in the cosmos.

ROWE: It'll be the most violent
event in the cosmos.

Let's put that in context.

We talk about how supernova
are some of the most explosive,

energetic things in
our universe.

Well, colliding supermassive
black holes

are a billion,
billion, billion,

billion times more energetic
than a supernova.

Think about all of the light
being emitted by everything in

the universe,
every star, every galaxy.

In one instant,
two supermassive black holes

colliding could release
100 million times that energy.

colliding could release
100 million times that energy.

Imagine being
punched in the face by

the biggest, baddest
heavyweight of all time.

Ouch.

This is way bigger than that.

ROWE: Where does
all this energy come from?

Surprisingly,
it originates in

the smallest atoms in
the cosmos,

in a story that dates back
billions of years,

all the way to the birth of
the universe.

ROWE:
We're taking our seats for

the most violent event
in the universe,

the collision of two
supermassive black holes.

We've never witnessed
this cosmic

heavyweight championship,

but we can build up a picture
of this epic fight by studying

other weight classes
with lighter fighters.

2020 -- the earthbound
gravitational wave detector,

2020 -- the earthbound
gravitational wave detector,

LIGO, picks up

the distinctive signal of
a stellar mass

black hole merger.

What we saw was a black hole
of 85 times the mass of our sun,

and another black hole of
66 times the mass of our sun,

smashing together to create
a combined black hole.

MINGARELLI: As someone who
studies black hole mergers,

this was a really
exciting event.

We're talking about

the largest, the heaviest,
the most massive

the largest, the heaviest,
the most massive

black holes we have seen
collide to date.

ROWE: It may be
the largest detection,

but on a universal scale,

it's still a small fry --
like lightweight boxers,

the two black holes
circle each other

and emit low energy
gravitational waves.

This energy loss causes
the black holes

to spiral in together.

Finally, they collide in
a cosmos-shattering event,

forming a single black hole

and releasing a huge blast
of gravitational waves.

But when astronomers examine
the single merged black hole,

something doesn't add up.

PONTZEN: If you take
the combined mass of

the two black holes,
you get to 150 times

the mass of our sun.

But actually, the black hole
that's left only has

a mass of 142 times
the mass of our sun.

a mass of 142 times
the mass of our sun.

So the mass you have
before the event does

not equal the mass you have
after the event.

What happened to that missing
eight solar masses?

The way these black hole mergers
work is very roughly 5 percent

of the total mass of
the system gets converted

into energy.

ROWE: It all comes down to
E equals MC squared.

This is that beautiful
equation that Einstein

told us --
E equals MC squared.

E is the energy,
and M is the mass.

E is the energy,
and M is the mass.

Einstein taught us that mass
and energy are related.

In fact, much of what we call
mass is actually energy.

ROWE: In this case,
the violence of the collision

transforms 18,000 trillion
trillion tons

of matter into an explosion
of gravitational waves.

SUTTER: In just
a fraction of a second,

eight suns worth of matter is
converted into pure

eight suns worth of matter is
converted into pure

unadulterated energy.

The amount of energy released
was so great, that if you add

up all the energy of all
the stars burning in

the universe,

it was bigger than that.

ROWE: This event was a collision
between relative lightweights,

two stellar mass black holes.

To understand
heavyweight bouts,

we need to scale up to
supermassive black holes.

we need to scale up to
supermassive black holes.

In the universe of sports,

supermassive black holes are
the heavyweight contenders.

With these big black holes,
size matters.

The bigger the better.

More mass means
more energy,

which means more
destructive power.

ROWE: We don't need to look
too far to find

this devastating muscle.

This is M87 star,

one of the largest
supermassive black holes

in our cosmic zip code.

in our cosmic zip code.

M87 star is huge.

It weighs about six billion
solar masses,

about six billion suns,

and it's the size
of our solar system.

ROWE: A collision between two
6-billion solar mass

supermassive black holes would
release around five

times 10 to the power of
56 joules.

So what's that mean
in real world terms?

It's hard to use words to
express how much energy this is,

and the numbers are so huge,
they are almost meaningless.

and the numbers are so huge,
they are almost meaningless.

The only way I can really
explain this is...

[exaggerated scream]

In physics,
we have these comparisons

so we can get a mental picture,

but for something like this,
there is no mental picture.

That is so freaking big.

ROWE: So where does
this destructive

mass and energy come from?

It starts with
the simplest ingredient --

It starts with
the simplest ingredient --

hydrogen.

Hydrogen is the basic
building block of the universe.

Each atom is tiny, but it
contains a lot of energy.

Hydrogen atoms contain a huge
amount of energy,

just like all matter does.

And if it's unlocked in

a certain way,
there can be huge explosions.

I mean, you take the mass
contained simply in my hand,

I mean, you take the mass
contained simply in my hand,

and you could blow up
pretty much the entire Earth.

ROWE: Matter has energy
because it formed from

energy in the early moments
of the universe.

In many ways,
atoms are reservoirs

of stored energy
from the Big Bang.

ROWE:
13.8 billion years ago,

the universe ignites

in a super hot ball of
intense energy.

Right after the Big Bang,
there's a tremendous

Right after the Big Bang,
there's a tremendous

amount of energy --
so much energy,

in fact, that normal atoms
can't exist.

As that early energy
starts to cool,

it can start to form
primitive matter.

ROWE: The universe takes
that first matter and energy

in the form of hydrogen atoms

and starts
the process of creating

a supermassive black hole.

Step one --
build giant stars.

So gravity brings
together gas, dust, hydrogen,

So gravity brings
together gas, dust, hydrogen,

all of that stuff,

and as the clouds
become more dense,

they attract
even more material.

NANCE: As they spin, they get
hotter and hotter, and as that

temperature
and pressure increase,

finally, it ignites
nuclear fusion within the core

and creates an actual star.

ROWE: These huge stars
are like cosmic rock stars.

They live fast and die young.

When they die, they flame out
in a huge explosion,

a supernova.

SUTTER: The entire star
turns itself inside out

and releases a shockwave
going a good

fraction of the speed of light
and releases enough energy to

just obliterate you.

ROWE:
If the dying star is more

than 15 stellar masses,

its core collapses
into a black hole.

It's kind of astounding
what the universe is doing.

It's kind of astounding
what the universe is doing.

It's taking incredibly simple
things, like hydrogen atoms,

and using gravity
to ultimately

bring all this stuff together
and make things

like black holes.

I find it quite beautiful
how our whole

cosmic history is
the story of

little things coming together
into bigger things.

ROWE: But these stellar mass
black holes are tiny

flyweights -- to step up to
the heavyweight division,

they have to grow billions of
times more massive.

they have to grow billions of
times more massive.

But how?

How do black holes
become supermassive?

This is the age-old question.

We're not really sure.

TEGMARK: The current state
of our understanding

of how black holes become
supermassive is like,

uhhh, we're confused.

We really don't know.

We still don't know exactly
how they become so big.

ROWE:
But we do know that

the process involves
ultraviolence,

the process involves
ultraviolence,

death, and destruction.

ROWE: How do supermassive
black holes grow so big?

That's a question that
continues to baffle scientists.

In June of 2018,
we spotted a clue,

an enormous flash of light.

AT2018cow,

nicknamed "the cow,"

was the brightest explosion
ever recorded.

A huge amount of energy
was released,

A huge amount of energy
was released,

and then all of a sudden,
everything was gone.

This explosion
was incredibly violent.

At first, it was thought

to just be a supernova,
a flash of light.

But over time,
it became clear

that this was something much
more powerful.

It was too bright, basically,
to be a supernova.

It was extremely bright,
and it didn't fit into

any of our theoretical
understandings

of how bright
supernova should be.

ROWE: One explanation is that
the light may have come from

a black hole feeding

a black hole feeding

on a small white dwarf star
weighing less than the sun.

What really seemed to fit that
model was a star getting

too close to a black hole

and getting ripped apart,
and then

everything going right down
the black hole.

PLAIT: A black hole gains mass
every time it eats something.

That's how they grow.

Whether it's a gas cloud
or a star or another black hole,

once it gains that mass,
it's gained that mass.

OLUSEYI: People often ask me,
what happens to

OLUSEYI: People often ask me,
what happens to

the mass that falls
into a black hole?

Does it go to
another dimension?

And the answer is no,
it's still there.

It's inside the black hole --
they get bigger, they grow.

ROWE: Could this be how weak
flyweight black holes

turn into mean and powerful

supermassive heavyweights?

The star is like protein,

and the black hole
is like a boxer.

And so the more protein
they get, the more stars

they consume,
the stronger they get,

they consume,
the stronger they get,

the more destructive
they can be.

ROWE:
But there's a problem with

the training program
explanation.

Eating small stars

one at a time just doesn't
add enough mass fast enough

to grow
the supermassive black holes

that we see today.

That's like boxers eating just
one egg per day.

Like them, black holes
need much bigger meals,

and in 2020, we detected one,

and in 2020, we detected one,

a sudden burst of
gravitational waves from

a black hole gorging on

the remains of a dead star

called a neutron star.

For scientists, January 2020
was exciting, because it was

the first time LIGO observed
the very first black hole

neutron star merger.

ROWE: Neutron
stars may be small,

but they are
inconceivably dense.

but they are
inconceivably dense.

Now, you want to talk about
an enormous amount of mass,

let's talk about
a neutron star.

That's -- that's one heck of
a snack.

ROWE: The black hole swallowed
the neutron star in one gulp.

So this black hole
ate a whole neutron star,

which means it gained just
over 10 percent of its entire

body weight in one shot.

ROWE: 10 percent doesn't
sound like a lot,

but then we detected another

black hole swallowing a neutron
star just 10 days later,

black hole swallowing a neutron
star just 10 days later,

suggesting that there are lots
of black holes bulking up

across the universe.

But even with this extreme
weight gain,

it's probably not enough to
get supermassive.

They need to eat even more.

If you're a black hole,
and you want to get bigger,

your best bet is to merge
with another black hole.

ROWE:
But there's a catch.

So if you're a flyweight black
hole, and you try to eat all of

So if you're a flyweight black
hole, and you try to eat all of

the other flyweight black holes,

there's just not enough time
in the history of the universe

for you to become
a supermassive black hole.

But you can make it
to middleweight.

ROWE: So exactly how
supermassive black holes

grow so large remains
an open question.

We do know that the process
started in the very early

universe with a journey

from the lightest
element to the most

intimidating object
in the cosmos.

intimidating object
in the cosmos.

It's so interesting how
the cosmos can take something as

simple as a hydrogen atom
and build stellar mass

black holes and intermediate
mass black holes

and even supermassive
black holes out of

these really densely compressed
hydrogen atoms.

It's really a wonder.

ROWE: Now,
13.8 billion years

after the Big Bang,
supermassive black holes

feed and flex their muscles,

ready to fight
for the heavyweight

ready to fight
for the heavyweight

championship of the universe.

These supermassive black holes
have been bulking up

since the age of
the universe.

SUTTER:
These black holes have been

getting ready for the fight.

They have been bulking up.

They have been eating
entire stars as snacks

to get the masks they need.

So they are ready to rumble.

ROWE: It's not the rumble
in the jungle.

This is the battle to be
the boss of the cosmos.

Supermassive black hole
versus supermassive

Supermassive black hole
versus supermassive

black hole, fought in
the grandest arena.

The fighter's entourage,
their host galaxies,

escort them to
the ring.

But even this journey
is violent,

triggering starbursts, jets,
and carnage.

ROWE: It's the build up before
the heavyweight fight

of the cosmos.

The fighters' entourages,
their galaxies, carry

their supermassive black holes
to the ring.

Things are about to get nasty.

Galaxies can look calm
and serene,

but they can get into
pretty big scraps.

There's a lot of them
that are totally

There's a lot of them
that are totally

messed up and are clearly
merging with each other.

ROWE: When galaxies fight,
their gravity pulls on each

other, twisting and distorting
their structures.

The galaxy will be warped
and morphed into different ways

that we can only imagine
how twisted it would be.

ROWE: This violent
cosmic tango brings

the two supermassive
black holes together.

the two supermassive
black holes together.

TREMBLAY: It's elegant,
it's beautiful.

It's this billion-year
choreographed dance

that is entirely conducted
by gravity.

ROWE: The two heavyweight
fighters approach each other.

Their feet beat out a rhythm
on the canvas,

just like circling black holes
release low energy

gravitational waves.

You have these giant beasts
that are stalking

around each other,
and as they do,

around each other,
and as they do,

they create these
gravitational waves.

ROWE: June 2021.

Astronomers photograph
a galactic collision

and witness a spectacular
pre-fight fireworks show.

One of the amazing things
that can happen

when galaxies collide
is they can create

tremendous starbursts.

There is a big inrush as all of

the gas follows that gravity --
as the gas gets hotter

the gas follows that gravity --
as the gas gets hotter

and denser,
it creates shockwaves,

and each shockwave actually
creates a new generation of

stars going out around
the core of the galaxy.

ROWE: The sudden starburst
lights up the merging galaxies.

The inrushing gas also fuels
the prize fighters,

the supermassive
black holes spiraling

towards the merging
galactic center.

PONTZEN: If there's a big
supermassive black hole,

it suddenly finds it
surrounded by loads of gas

it suddenly finds it
surrounded by loads of gas

and other material it can eat.

It goes on a kind of
feeding frenzy.

If you're a hungry
supermassive black hole,

then this is
your lunchtime buffet.

ROWE: Not all the gas falls into
the supermassive black hole.

Other parts of the matter
actually gets caught up

in what we call
an accretion disk

rotating around the outside
of the black hole.

ROWE: This bright vortex spins
around the supermassive

ROWE: This bright vortex spins
around the supermassive

black hole at over
two million miles an hour.

The material in the disk
rubs against itself,

creating friction.

Friction generates heat --
if I rub my hands together,

they get a little
bit warm.

If I rub my hands together at
hundreds of thousands of

miles per hour, it's gonna get
very, very, very warm.

ROWE:
The accretion disk heats up,

blasting out intense light.

In 2020,

NASA's Hubble space
telescope saw two fueled-up

supermassive black holes
lighting up for the fight.

We call them quasars.

Quasars are a subclass
of very bright black holes

that are emitting huge
amounts of power.

So these can be seen at
the far reaches of the universe.

TREMBLAY: Black holes,
these so-called dark things,

TREMBLAY: Black holes,
these so-called dark things,

when they're growing
at a very high rate

are some of the brightest
lights in the universe.

ROWE: To date,
we've detected over 100 pairs

of quasars in the cores of
merging galaxies.

We think they will all
eventually collide,

but before they do,
they'll put on a spectacular

and lethal light show.

A common theme
in science fiction

are different kind of jets
of energy or beams

are different kind of jets
of energy or beams

that people shoot out of
their eyes or their hands.

Well, supermassive black holes
do that, too.

ROWE:
Firing out relativistic jets.

When those jets fire up,

that's when you're talking
about superstar, really,

really bright lights, and at
this point, the galaxy is lit up

and ready to go.

These are the spotlight's
on Madison Square Garden.

This is telling you that
the event is going down.

This is telling you that
the event is going down.

[crowd cheering]

A single supermassive
black hole jet

will produce more energy
in a second

than the sun will produce in

its entire
10-billion-year lifetime.

Imagine a laser of
radiation that

is light-years
in length and across.

That's what
we're talking about.

This thing would
fry a planet.

ROWE:
This is no pre-fight hype.

ROWE:
This is no pre-fight hype.

In February 2020,
we saw the impact of a jet.

TREMBLAY: So in the Ophiuchus
galaxy cluster,

there's an enormous void
that is 15 times wider than

the Milky Way galaxy.

And this has all been
sculpted, carved,

by jets from
a supermassive black hole.

STRAUGHN: It's like this scar
on the universe.

It's a million
light-years across.

It's huge.

ROWE: Scientists calculate
the impact of the jet hitting

the cluster was equivalent to

the cluster was equivalent to

a 20-billion-billion megaton
TNT explosion every 1,000th of

a second for 240 million years.

The relativistic jets'
immense power may be

a showstopper.

But when it's time to land
the killer punch,

supermassive black holes draw
on an even more powerful force,

gravity.

STRAUGHN: Jets are very
powerful, but really

only on a relatively
small scale.

only on a relatively
small scale.

When you're talking about
cosmic scale,

gravity always wins.

Nothing is as powerful
as gravity.

ROWE: The immense gravity
of the circling

supermassive black holes
drags them ever closer,

but will it ultimately
bring them together

or blast them apart?

ROWE: Across the universe,

supermassive black holes
duke it out

in the cosmos's version of
heavyweight super fights.

Supermassive black holes are
merging around us all the time.

It's only our ability
to detect them

that's preventing us
from seeing them.

ROWE: Scientists have
identified at least a dozen

ROWE: Scientists have
identified at least a dozen

pairs of supermassive black
holes circling each other.

We have some hints
of some galaxies

where we think
it might happen,

where we see two glowing black
holes that are getting

very close.

ROWE: But not all these matches
will end with a knockout.

Black hole collisions
happen all the time.

But they don't always
go according to plan.

When black holes
come together,

really strange things
can happen.

ROWE: The Hubble space telescope
spots something strange in

ROWE: The Hubble space telescope
spots something strange in

a distant galaxy
called 3C186.

It's a quasar, an active
supermassive black hole.

But it's in
the wrong place.

In nearly every galaxy we see,
the supermassive black hole

sits right at the center,
and that makes sense.

SUTTER:
Because that's the only place

with enough material to
power them.

But in 3C186,
that's not what we see.

But in 3C186,
that's not what we see.

The supermassive black hole is
displaced from

the center,
and not a little bit.

It's 35,000 light-years.

So to see a quasar
35,000 light-years away from

the core means something
really violent

had to happen there.

ROWE: The quasar is racing
away from the center

of the galaxy at over
four million miles an hour.

OLUSEYI:
That is insane.

The magnitude of the energy

and the forces required are
just something unimaginable.

and the forces required are
just something unimaginable.

So what can kick a giant
black hole out of a galaxy?

What has that kind of power?

ROWE: The answer is a clash
that wasn't evenly matched.

The two supermassive black
holes were different sizes --

a middleweight boxer
taking on a heavyweight.

When we humans set up a fight,
we like to make it fair,

because it's sport.

Nature doesn't care
about sport.

It's survival of the fittest.

It's survival of the fittest.

This is not a fair fight.

It's over before
it even begins.

One punch,
and it's a K.O.

As these two black holes
are merging,

there's one
really small black hole

and one much bigger
black hole.

The whole system wobbles
around, and it can get more of

a gravitational wave kick in one

direction than the other.
-And that's momentum.

That's a push,
that's enough energy to kick

the black hole out.

ROWE: The lopsided
gravitational punch

ROWE: The lopsided
gravitational punch

sends the merged supermassive

black hole on a one-way trip
to oblivion.

This tells us
that gravitational

waves can be
tremendously powerful.

They can move a supermassive
black hole out from

the center of a galaxy
and send it on its way.

PONTZEN: But it just carries
on drifting.

There's no way to stop it.

And who knows, in a few
million years it could

just drift entirely
out of its galaxy

and go floating off
into deep space.

and go floating off
into deep space.

ROWE: In some matches,
the fighters

don't even land a punch.

Scientists spot
a supermassive black hole

named B3 1715+425.

This black hole is strange.

Stripped of all its stars,

it hurtles through empty space
at 4.5 million miles an hour.

The first thing
that draws our attention is

this faint trail of debris
across the sky.

this faint trail of debris
across the sky.

PLAIT: There is actually
a trail leading

back to the center of
the galaxy.

It's kind of like a dump truck,
right, that's filled with

dirt driving down the highway,
and the dirt's flying off

behind it --
this is a naked black hole.

ROWE: The exposed
super massive black hole

has lost its stars and galaxy,

a champion stripped of
its fans and entourage.

So what event is powerful
enough to strip

a supermassive black hole of
its entire host galaxy?

a supermassive black hole of
its entire host galaxy?

That has to be something
really big.

PLAIT: B3 is
a smallish galaxy, and it

got into a scrap with a much
bigger one.

The stronger gravity of
the bigger galaxy

stripped the stars away from
that black hole and shot it out.

Typically in the universe,
when something

is bigger and more massive,
it wins.

So this is true for galaxies.

A big galaxy versus
a little galaxy --

put your money on the big one.

ROWE: But when two
evenly matched heavyweights

ROWE: But when two
evenly matched heavyweights

enter the ring,

it's time for the main event.

[crowd chanting]

A clash of the titans.

I grew up watching boxing
with my dad.

So I've always been a boxing
fan, and I love a great battle.

And what's a bigger
battle than

a head-on collision between
two supermassive black holes?

If you're a boxing fan,
this is the big one.

SUTTER:
We are ready.

We are on the edge of
our seats.

We are on the edge of
our seats.

MINGARELLI: We've got two
supermassive black holes,

each one is in their corner,
and they're getting ready for

the fight of the century.

I mean, they're just gonna
go at it like goosh, goosh.

I would watch that.
I'd Pay-Per-View that.

OLUSEYI: It doesn't get
any better than this.

These are prize fighters
at the top of their game.

They're trained to a T.

They're beefed up.

They are ready to rumble.

ROWE: We are just seconds away
from the fight of the cosmos.

ROWE: We are just seconds away
from the fight of the cosmos.

ROWE: Welcome to
the heavyweight championship

of the universe.

Weighing in at eight billion
solar masses,

We have the galactic
destroyer, M101 star.

And in the other corner,

at a punishing
7.8 billion suns,

the star crusher,
NSC47 star.

the star crusher,
NSC47 star.

They are pumped
and ready to rumble.

So here it is,
we're finally here.

The crowd is roaring.

The bell has rung,

and the fighters are
approaching each other.

They are ready to go at it.

ROWE: Let's have
a clean fight, fellas.

Touch hands,
and go back to your corners.

Round one.
The two heavyweights circle,

testing the other's defenses.

The black hole's gonna do what
the boxes are gonna do.

The black hole's gonna do what
the boxes are gonna do.

They're gonna circle
each other,

and they're gonna orbit
each other,

and they're gonna
size each other up.

PLAIT: Once these two
supermassive black holes

are close enough,
their gravity,

inexorably, is gonna
draw them together.

ROWE: As the two supermassive
black holes get closer,

they throw a few
exploratory jabs,

triggering bursts of
gravitational waves

that warp everything
in their path.

that warp everything
in their path.

These enormous gravitational
waves are completely

deforming the fabric of
spacetime around them.

Not just a little bit,
but a lot.

It's like feeling
the fighters approach in

the boxing ring...

from the next town over.

ROWE: Next, the supermassive
black hole's gravity throws in

a couple of right hooks

straight into
the accretion disks.

MINGARELLI: What could happen is
that they start to form

like an angle grinder.

You'll see sparks flying as
they try to merge and form

a new single accretion disk.

When those accretion
disks collide,

the whole thing is gonna light
up like the Fourth of July.

ROWE: Spiraling in at millions
of miles an hour,

the heavyweight fighters
get close,

delivering punishing
body blows.

delivering punishing
body blows.

The event horizons,
the surface of

the supermassive black holes,
are about to touch.

In their final moments,

these two supermassive black
holes are orbiting each other

at a significant fraction

of the speed of light,
and their event horizons

will touch.

And they'll eventually
merge into one new

supermassive black hole.

TEGMARK:
You might think,

don't they bump into each
other like bowling balls?

don't they bump into each
other like bowling balls?

No, they don't.

Because what we're calling
the edge of a black hole is

actually not a thing --
that's just

the surface around
the black hole.

Gravity is so strong
that nothing can come out.

ROWE: The two supermassive
black holes finally merge,

releasing around 5 percent of
the mass they've gathered over

billions of years in

an enormous burst of
gravitational waves.

The amount of energy
that we're talking about...

there's nothing to compare it
to -- it's mind-crushing.

There's really almost no point
in thinking about it.

It's just not something
I think that I can

wrap my head around.

Coming from where
I come from,

you know, you don't
show weakness,

so I'm not gonna say that
the collision of two black holes

is more powerful than one of
my punches, but...

it's close.

ROWE: The gigantic and powerful
gravitational waves race out

from the collision zone,

leaving a single merged
black hole.

The supermassive black hole,
after it merges, permanently

deforms the fabric of spacetime
around it, and this deformation

travels out at
the speed of light.

ROWE: The surviving 95 percent
of mass from the two colliding

supermassive black holes

is now locked in a single
ultramassive black hole,

the undisputed super
heavyweight champion of

the universe --
at least for now.

It seems the universe is
always upping the ante.

Could there be something
even more

violent we haven't even
discovered yet?

The universe
keeps wanting to give us

something more violent
all the time.

ROWE: Energy locked in hydrogen
atoms formed at the birth of

the universe is finally

released in the violent
collision and builds

an ultramassive black hole.

SUTTER: This is one of the most
beautiful stories in

our universe -- you have
the most energetic collision,

the most amount of
energy released,

the most violent event,
can trace

its origins to the humble
hydrogen atom.

ROWE: So we have our
champion -- matter compressed

and then smashed together
by supermassive black holes

creates the most violent event
in the universe.

I don't think
there's a contest.

I don't think
there's a contest.

The supermassive
black hole collisions

are the most energetic,

just, like, mind-numbingly
large amounts of energy in

these collisions.

A merger of two supermassive
black holes

is at the absolute top end
extreme of that

for all possible events
in the entire universe,

A supermassive black hole
merger is the most

violent thing that we can
observe in the universe.