Original subtitles

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.

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.

2021, scientists detect

a gigantic rumble deep in space,

a tsunami of gravitational waves,

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.

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

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.

[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.

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.

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,

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.

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

[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.

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.

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 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.

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.

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,

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

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.

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.

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

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.

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.

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.

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--

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,

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

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,

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 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.

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,

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,

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

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

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,

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,

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.

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,

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

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.

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

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

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

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.

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,

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

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

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

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,

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

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.

[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.

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

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.

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

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

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.

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.

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.

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

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.

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.

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?

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

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.

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: 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.

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.

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.

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.

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?

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.

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.