Original subtitles

*

A journey to infinity...

and beyond.

A place where the rules of physics collapse,

where time and space twist and distort.

Travel back to the past...

..and see into the future.

Enter the most extreme, least understood place in the universe...

..the heart of a supermassive black hole.

A black hole - terrifying and fascinating,

the universe's ultimate enigma.

How can you not love a black hole? It's the end point of everything.

It's distorting space, distorting time.

There's some ideas that if you fall into one,

you could pop out someplace else in the universe.

It's a science fiction writer's dream.

And now consider that these things are real,

that we actually observe thousands of them, routinely.

Black holes are monsters, real monsters in our midst,

and they will never cease to be dramatic.

What would we see if we could look this monster in the eye?

I would love to have a trip around a black hole.

Looking out the window, seeing this scary black disc in front of you,

and marvelling at the gravitational distortions of light.

And experience this spectacular manifestation of all the stuff

that I've just calculated and never seen.

What would we discover

if we could actually venture inside a black hole?

We're going to find out,

because we're sending an imaginary probe

to the supermassive black hole at the centre of the Milky Way.

It's called Sag A*.

It's so far away

that even if the probe could travel at the speed of light,

it would take 26,000 years to get there.

On the journey, the probe would pass

tens of thousands of smaller black holes.

We think there is a sort of a zoo of black hole sizes.

There's hypothetical microscopic black holes.

There's middleweight black holes that are formed when stars collapse

and maybe another star falls onto them.

Then there's the supermassive black holes.

They're lurking at the centres of galaxies.

Most black holes are born when a giant star dies.

When the star collapses, it all gets blown out

in the most violent fireworks in the universe.

A super nova, the explosion of a star,

which shines briefly with the brightness of 10 billion stars.

After the explosion, gravity seizes control of the star's core.

A star is already crushing itself down under gravity,

but what stops it is the pressure of the light coming out of it.

So if a star can no longer produce that light,

it's gonna crush itself down.

And it'll get smaller and smaller and smaller

until finally, no force can hold it up,

and it just crushes in on itself.

Gravity pulls every speck of matter inwards,

crushing lumps of solid iron the size of Mount Everest

down to the size of grains of sand.

You think about solid matter as being something that's so solid,

so strong, that it can't compress any more. Think of iron.

But really, iron is mostly space.

The space between the protons

and neutrons at the core of that iron atom is huge.

So at some point, for some stars, the compression is so large

that you can end up smashing these core neutrons and protons together.

What happens next is not well understood.

Gravity squeezes these subatomic particles together

in ways that science has yet to explain.

The inside of a collapsing star is unimaginable.

There are temperatures and pressures

that we don't really even have very good numbers for.

We know for a fact that we will need new physics,

things that we have not yet discovered

to explain what goes on inside a black hole.

But we do know that the giant star is crushed down

to a fraction of its former size.

Although the amount of stuff inside it,

its mass remains the same.

Such a massive object squeezed into such a small space

creates a gravitational field so strong nothing can escape.

The result is a black hole.

Most are roughly 20 times more massive than the sun.

But at the centre of galaxies,

black holes grow to become billions of times bigger.

Their size and power is unimaginable, earning them their own special term.

The coolest word in astronomy is supermassive black hole.

As you can tell by the name, this supermassive black hole

is consuming a supermassive amount of material,

and we know that there's one in the centre of our Milky Way galaxy.

This supermassive black hole Sag A*

is the final destination of our imaginary probe.

Supermassive black holes are actually quite omnivorous.

They like to eat gas but, you know, if a star comes within reach,

they'll gobble that up, too, or a planet or a spaceship, whatever.

They're not so fussy.

They even eat each other.

But over billions of years, many stars could die in one area

and the resulting black holes can move together

and combine into bigger and bigger black holes.

Sag A* is an omnivore and a cannibal.

It has gorged on anything and everything within reach

for at least 12 billion years.

The reason that the black hole can fit within it

all these enormous amounts of stuff it's eating

is cos it's like the ultimate trash compressor.

It just squeezes the matter down to ridiculously small scales.

So the weight of a black hole

is simply the sum of everything it's eaten

since the beginning of our universe.

After billions of years of eating,

Sag A* has grown to 4.6 million times more massive than our sun...

..but it's only 20 times wider.

Outside its black sphere

spins a luminous veil of stars, dust and gas.

As the probe approaches, something strange starts to happen.

The probe looks like it's veering off-course,

even though the probe's instruments maintain

that it's travelling in a straight line.

From the probe's perspective, nothing weird is really happening.

But if you're on the outside, looking at this probe,

this straight path is not going to be a straight path.

It's gonna get pulled off the straight path

by the actual space around the black hole.

The probe's course hasn't changed, but the space around it has.

And as space changes,

so does time.

Time flows differently when you get near a black hole.

If the black hole is spinning, it drags space around with it.

It is just bizarre and they take all of our concepts

of common sense and intuition and everything

and just chuck them right out the window.

Sag A* distorts space and time.

So as the probe draws closer, time begins to warp.

At the black hole,

the ultimate science fiction fantasy becomes reality -

the probe really can travel back to the future.

*

*

As the imaginary probe nears the supermassive black hole

at our galaxy's heart, something strange starts to happen.

The probe experiences one of the most extreme

and fundamental forces in the universe.

A force with the power to twist space

and send the probe travelling through time.

Gravity is something incredibly commonplace.

We're always dropping things.

We're not flying off the surface of the Earth.

It's a part of our lives from the moment that we're born.

But it turns out it's a very mysterious

and deep part of the universe.

When something has mass, it has the ability to bend space.

Before Einstein's theory of general relativity,

scientists imagined space as a stage on which the action plays out.

Einstein's genius was to realise

that space itself was an active member of the cast.

We tend to think of space as just this stuff around us,

but it's actually kind of a thing,

it has a physical component to it like a fabric, like a sheet.

The fabric of space is usually flat,

so light travels through it in a straight line.

But a massive object like the sun, with its strong gravitational pull,

bends the fabric...

..so the light appears to bend as it passes the sun.

So light bends, not because the light bends,

but the space in which the light is travelling curves itself.

This is why, as the probe nears Sag A*,

it looks like it's going off-course.

The immense gravity around the black hole

is warping the fabric of space.

So everything, even the light

that travels through this warped region of space,

must follow the same curved path.

The amazing thing is

that not only does gravity warp the light into the black hole,

light coming from farther away gets bent around it.

And so you could see this shimmering distortion

against the stars in the background as a black hole moved in front.

It would almost be like taking a piece of glass

and moving it across the star field.

The black hole isn't just bending space,

it's also warping time.

So if we send a probe going into a black hole,

from our point of view, we see it falling in.

And we see it falling in more and more slowly

because its clock is ticking slower and slower and slower.

That's a bizarre concept,

and it's really hard to wrap our brains around,

but that is what the math and physics are telling us.

We experience time as hours, minutes and seconds.

It seems straightforward,

but actually time is relative,

it changes depending on where you are.

It seems to the viewer that this shot

has a picture of a moment in time and a moment in space,

but it's actually not a moment in space and a moment in time.

It's spread out in space,

because there's some depth of field behind me.

But it's also spread out in time,

because the light from the whiteboard behind me

left the white-board a little bit earlier than the light from my face.

So when you see an image,

you're really seeing something that's spread out in space and time.

Space and time are inextricably linked.

So when gravity bends space, it also bends time,

and the stronger the gravity, the more time is distorted.

Time does not flow at the same rate everywhere in a gravitational field.

The farther down you are into the gravity, the slower time goes.

Now, we actually have clocks that are accurate enough today

to tell the difference in time between being in the basement

and being in the attic. That's really true.

Time really goes faster in the attic than it does in the basement.

A day spent at the top of the Empire State Building

will make you a few billionths of a second older

than someone who stayed on the ground floor.

That's because the Earth's gravitational pull

is slightly stronger on the ground floor,

and the stronger the gravity, the more time is slowed.

The existence of mass and energy in space, curves space.

So right now, I'm curving space-time around me.

And as you get to more and more massive objects,

that curvature becomes greater and greater.

So the Earth is curving space-time, the sun is curving space-time.

And when you get to black holes, the curvature is incredibly extreme.

As the probe nears the supermassive black hole,

it starts to travel through time.

It's hard to wrap your mind around this concept of space-time

and even of black holes, it's pretty insane.

If I'm near a black hole,

I'm video-conferencing my mom on a computer,

she would actually see me go,

(SLOW AND DISTORTED) "Hi, Mom."

But I would feel that my time is running normally,

whereas she is acting weird, going...

(FAST) "Oh, my goodness, I'm a little worried about you because you're speaking so funny."

Close to a black hole, you really can go back to the future.

And if you go back, people would say,

"Oh, you look so youthful. This was a rejuvenating vacation."

I'd be like, "Yes, because my time slowed down."

As the probe travels closer, gravity's grip increases,

and time ticks progressively more slowly.

But the increasing gravity has another effect...

..it accelerates the probe towards the black hole.

But in its path is a cosmic kill-zone...

..a ring of molten dust and gas, tens of millions of kilometres wide...

..known as the accretion disc.

It threatens to rip the probe to shreds.

You've got this matter falling into a black hole, it forms a disc,

and there's friction inside of this disc.

Things are rubbing against each other,

and the velocities are so huge that this disc becomes terribly hot

and it glows when it gets that hot.

And so, ironically, even though black holes are dark,

as matter falls in, it can light up

and be the most luminous objects we see in the universe.

The probe plunges headlong towards this seething disc of matter.

Collision seems inevitable...

..but then a remarkable thing happens.

Without firing any thrusters or manoeuvring in any way,

the probe swerves.

Rather than colliding with the spinning disc, the probe joins it,

its course altered by an unseen force.

Almost everything in the universe spins in some way or another.

That is due to angular momentum -

this tendency that once you get something spinning,

it's gonna stay spinning.

When you think of that classic example

of an ice skater spinning on an ice rink,

and as she draws her arms in, she begins to spin faster and faster.

Think about the scale involved

when you go from a giant star to a tiny hyper-compressed black hole.

That spin was sped up and sped up and sped up.

As the matter falls towards the black hole,

it whirls around faster and faster, reaching astronomically high speed.

Travelling at close to light speed,

the matter spins too fast to fall into the black hole.

For example, there's a very famous ride in fairs

where you can be in a room and it starts spinning,

and you're pushed against the wall and the floor recedes.

But you stay up, you don't slide down.

That same effect can stop you from falling into a black hole.

Spin something fast enough and centrifugal force overpowers gravity.

There's this sort of Yin and Yang tension

between gravity trying to crush things

and the centrifugal force of spin trying to blow things apart.

But the black hole doesn't just spin matter around it,

it spins the fabric of space around it, too.

Picture a dust devil, a kind of mini tornado.

The swirling dust reveals the movement of the unseen wind.

In the same way, the spinning matter around the black hole

reveals the unseen movement of space itself.

A spinning black hole creates

a kind of tornado in the fabric of space and time.

Black holes are weird, no matter how you look at them.

Everything about them is just so strange.

But I think the weirdest thing about them is the fact that

they can drag space and time, that fabric, around with them,

wrapping themselves in a cloak of the material of the universe itself.

General relativity tells us that

any massive spinning object, even the Earth,

should move the space around it in a process called frame-dragging.

Now, when we go to the case of the extreme gravity of a black hole,

when we talk about frame-dragging, we're talking about a region

where the space is actually being dragged so strongly

that it's impossible to remain at rest there.

The probe is spinning through twisted space and time.

Things would look very warped and distorted.

And what you see in front of you

might even, in fact, be in back of you.

And much of our intuition for what's where would actually break down.

Rotating wildly, twisting space and time,

black holes are not simply monsters

that feast on everything within reach.

The thing about a black hole

is that they eat like they're toddlers, they're messy.

So as stuff is falling in,

a lot of it doesn't ever actually make it inside the black hole.

Physicists estimate that up to 40% of the dust and gas

in the accretion disc never enters the black hole.

It's only when you're inside the black hole that you're doomed.

But just a little bit outside the black hole,

if you're going around fast enough,

you can exist that way for a long time.

In fact, black holes don't just pull material in,

they also blast it out.

This accretion disc is whirling madly around the black hole.

There's friction, there are magnetic fields.

And it can twist these up and they can form

sort of cone-shaped magnetic cannons

that point out the top and the bottom of the black hole.

And material can flow along that

and be ejected outward at almost the speed of light.

These galaxy-sized cannons are called quasars.

At their heart, powering the blast, is a supermassive black hole.

If there is a place in the universe you don't want to be,

it's looking down the barrel

of one of these jets coming from a black hole.

We see images of galaxies with supermassive black holes

with jets coming out and they're hitting galaxies nearby.

And the environment in that target galaxy

is probably completely inhospitable for life.

Quasars can rip vast cavities in galaxies,

preventing stars from forming.

But by blasting matter far across the universe,

they may provide the raw materials for the formation of new stars.

Black holes we think of as destroyers, certainly in movies,

because everything falls into them and literally, once you're inside,

your future isn't very good.

But we are beginning to think more and more

that black holes play a central role

in the evolution of everything we see.

Without black holes, our solar system may never have formed.

But if our solar system ever found itself

in the line of fire of one of these jets...

..we would probably be annihilated.

Luckily, Sag A* seems to be quiet and our probe is unlikely

to be blasted out into deep space on a giant magnetic jet.

Still, progress towards the core is slow.

Suspended between spin and gravity, the probe spends thousands of years

staring into the black hole's blank face.

However, gradually, gravity wins,

dragging the probe ever closer to the edge of oblivion.

To a place where time stands still

and a wall of fire threatens to obliterate everything.

*

*

The probe is on the precipice...

..about to enter the gaping mouth of the black hole -

the event horizon.

Black holes have something called the event horizon,

and it's the point at which there is no escape

from the gravitational pull of the black hole.

Once you cross the event horizon,

it's similar to going over the edge of a waterfall, there's no return.

If you look at this waterfall, you'll see it's sort of going flat

and then suddenly at the edge, water's falling steeply down.

The edge of a black hole is sort of like that.

At the event horizon, suddenly, space begins to bend deeply in.

Gravity pulls the water across the edge and down the waterfall

in the same way that it pulls space and time

over the event horizon and into the black hole.

Just like a fish exists in water, everything exists in space-time,

and that includes light.

So a little light ray falling over the event horizon of a black hole

is never gonna be able to come back out.

For a fish to travel back up the waterfall...

..or for light to escape from a black hole...

..it would have to travel fast enough to overcome the pull of gravity.

And the stronger the gravity,

the faster the object needs to travel.

To escape the Earth's gravity,

a rocket must travel at 11 kilometres per second.

From the far-more massive sun,

the escape velocity soars to 618 kilometres per second.

Black holes have gravitational fields

that are so much stronger than that.

In fact, rather than the speed of a rocket to escape,

even if you go the speed of light, you'll never get off.

In the few remaining seconds before the probe tumbles past the event horizon,

the pull of gravity and its distortion of space-time

increases dramatically.

Suppose I have a clock and the probe has a clock

and I can observe the probe's clock and my clock.

As the probe gets nearer and nearer

to the event horizon of the black hole,

I will observe the probe's clock actually stop.

Right at the event horizon, time basically grinds to a complete halt.

So if I were sitting on the event horizon of a black hole,

or almost on it, and you looked at me...

..I would just seem frozen to you.

You never actually observe

an object falling into the event horizon from the outside.

Because it will take longer than the age of the universe

for us to watch the object disappear.

Near the black hole's event horizon,

time seems to slow to a virtual stop...

..and objects appear to change colour.

As you fell into a black hole,

people would see you being redshifted.

They would see light coming from you losing energy,

because it has to climb out of this incredible well of gravity

to get out of the black hole.

The same phenomenon occurs with sound.

When a fire engine speeds towards us, the sound waves compress.

Racing away, they stretch out.

Like sound, light travels in waves.

But instead of changing pitch, light waves change colour.

Climbing out of the black hole's gravity,

light waves are stretched and turn red.

That's why black holes, in some sense,

sound like the stuff of science fiction.

But the real universe is stranger than science fiction,

that's what's so wonderful.

And what's even more wonderful is we don't know exactly what happens

at the event horizon of a black hole.

Einstein's theory of general relativity predicts

the probe will simply glide through the event horizon.

So this probe, if it's going past the event horizon,

there's not going to be a sign post there that says,

"Welcome to the event horizon".

It won't notice anything different.

You just cross this boundary

and then suddenly, you're cut off from the universe,

never to return again. That's pretty wild.

But according to a radical new theory,

the probe's descent into the abyss won't be a gentle freefall...

..it'll be a baptism by fire in the ultimate cosmic firewall.

So a computer firewall is simply supposed to be

an impenetrable barrier,

whereas the black hole firewall is literally a wall of fire.

And that means that it's not innocent near the event horizon.

It's not just empty space with a few soft photons

that you can barely notice.

Rather, there's this hugely dense radiation bath of photons.

This new theory turns the event horizon

into the most dangerous place in the universe.

An inferno of infinite energy

incinerating anything that touches it.

There is no doubt that there is a place in space,

the event horizon, the place from which nothing gets out.

But the million-dollar question is,

what actually happens there if you jump in?

Some people think that nothing special happens there,

and other people think

that you actually get burned up by this firewall.

And what's so embarrassing about this is,

if you actually want to find out and decide to jump into a black hole,

you will learn, but you can't tell anybody else.

The frustrating thing about black holes is, because it has this event horizon,

and we know that light cannot be emitted past that threshold,

even with all of our advanced telescopes, it's very difficult to detect.

To resolve what happens on SAG A*'s event horizon,

we need to build a telescope as big as the Earth.

It sounds impossible,

but it's already taking shape at Hawaii's Mauna Kea Observatory.

If you want to see the black hole

at the centre of the galaxy, you need a really, really big telescope.

We can't build optical telescopes that big.

And what we do is we use radio telescopes

and we distribute those telescopes

over thousands of miles apart from each other.

So we're creating a telescope that's as big as the Earth itself.

And over here is where it all comes down.

And inside of this rack,

all of our signals come in here at eight gigabits per second.

It's the equivalent of four digital movies per second.

If we sent this back by your home internet connection,

it would take years to transmit all of this data.

So what we have to do is specially package this up

and ship it to our central lab at MIT where we process this data.

This is essentially the holiest of holies. This is ground zero.

This is where all the data come together.

By accumulating two more years' worth of data,

scientists believe the event horizon could be brought into focus.

So once the event horizon telescope gets its final data sets,

we hope to image something like this.

This is what we wind up seeing, though, because the intervening gas

to the centre of our galaxy blurs the image.

But if we take out the scattering,

we wind up being able to recover the shadow feature.

This is what we're after, this is the Holy Grail

of the event-horizon telescope.

The event horizon is already taking shape...

..a black sphere, 27 million kilometres in diameter.

This is what the probe should see in the final moments

before it enters the abyss.

If there is a firewall lurking behind this black veil,

the probe will be destroyed.

If not, the probe will glide across the event horizon without incident...

..only to find itself in the most bizarre and most extreme place in the universe...

..where new worlds begin and the past becomes the present.

*

*

The probe has passed the point of no return.

It's now inside the supermassive black hole...

..plunging through a world of unimaginable extremes.

Everything that falls into a black hole disappears.

And if it never gets out, the question is, where does it go?

Here, gravity is so intense that the fabric of space itself

is pulled inwards at speeds faster than the speed of light.

The 13-million-kilometre journey to the black hole centre

will take less than 40 seconds.

But only if the probe can survive the extreme gravitational forces.

Now, imagine that I've fallen into a black hole.

The strength of gravity is gonna be different

if I'm going in feet-first,

because of the extreme curvature of space-time there.

And because of that, my feet will have a stronger pull

and you will get stretched into a form

that's reminiscent of spaghetti.

So we call it spaghettification.

Spaghettification is real.

It happened when Jupiter's gravity spaghettified Comet Shoemaker-Levy 9

into a chain of fragments in 1994.

In reality, the probe would be stretched into atom-sized filaments

before it reached the black hole's centre.

I mean, of course, I could flex and hold myself together anyway,

but, you know, it's the laws of physics we're battling with here.

(LAUGHS)

But let's suspend these laws

and equip the probe with a protective force-field

straight out of science fiction.

It's now halfway from the event horizon to the black hole's centre.

From this vantage point,

the probe sees something truly incredible.

If you were talking about the exact mathematical horizon,

you would see the entire past of the universe go by.

You would see back to the beginning of the formation of the black hole.

According to Einstein's equations,

the black hole is a colossal cosmic museum.

All the light that's fallen in

since the black hole's formation is still here, sped up,

and stacked in layers.

As the probe plunges deeper,

the battle between gravity and spin resumes and intensifies.

The centrifugal force gets relatively stronger

deeper inside the black hole.

And that centrifugal force slows down the flow of space,

and the place where it slows back down to the speed of light

is called the inner horizon.

And all kinds of crazy things happen at the inner horizon.

In this chaotic cosmic blender,

matter gets spun around and flung back out.

If I actually jump into a big black hole,

just like if I fell down a waterfall,

you're gonna be perfectly alive and well while you're on the way down.

The problems only come when you reach

what corresponds to the inner horizon at the base,

where other water and rocks and things come at you.

Now the probe nears the inner horizon.

The inner horizons of rotating black holes

are the most violent places in our universe.

Wildly energetic particles slam into the probe at near light-speed.

The black hole, it's an amazing kind of...

particle accelerator at the inner horizon.

Particles spewing in all directions,

being accelerated through each other.

They collide together, they produce enormous concentrations of energy,

which vastly exceed any energy

in any terrestrial particle accelerator.

The collisions are comparable in strength to the Big Bang.

If there is any place in our universe

where our universe is making baby universes, where our universe is reproducing,

I can guarantee to you that that place is the inner horizons of black holes.

Because that is the place where the energies

that are needed to make a Big Bang, they are produced there.

The idea that a universe can be born inside a black hole

led scientists to question the origins of our own universe.

It's actually completely possible that our Big Bang

is the remnant of a black hole in some pre-existing universe,

crushing things together, then spitting out a baby universe.

One of the reasons black holes are such fascinating objects

for theoretical physicists is they may provide a guide

to a new understanding of the universe.

So if we understand black holes, we may understand the Big Bang.

If we understand the Big Bang, we may understand our very origins.

As the probe crosses the inner horizon, everything changes.

The gravity pulling the probe inward is matched

by the spin pushing it out.

The two opposing forces are finally balanced.

So what this creates in the centre,

in the very region of the inner event horizon of one of these black holes

is sort of like a safe haven, like the eye of a hurricane.

And in there, things are a lot calmer

and you could imagine actually navigating,

once you get through the crazy region on the outside.

Inside the eye of the storm,

the probe heads for the black hole's heart -

the singularity.

Here, space and time and our understanding of the universe ends.

Inside the inner event horizon of a spinning black hole,

you can look at the singularity, it's over there in a ring.

The actual thickness of the ring is zero.

It is a circle of points

of infinite mathematical thickness

and infinite curvature of space-time.

This was once a massive star, crushed down to an infinitely small,

infinitely dense point in space and time.

Spinning at astronomically high speed,

centrifugal force transforms this point into a ring

which warps the space and time around it.

And it turns out that around the singularity there's a region

where we have, what in the jargon is called, a closed timelike curve.

Which is a fancy way of saying, "You can enter this region,

you can zoom around and then you can come out,

and you come out before you went in."

So you can basically visit the past version of yourself

before you ever entered.

OK. (LAUGHS)

General relativity predicts that the singularity will bend

space and time to such an extent

that if the probe took a trip around the ring,

it could come back to a time before it set off.

But this probe is heading straight through the ring.

There's this idea that a black hole is punching a hole

in the fabric of space and time.

And that it might be punching a second hole

someplace very far away.

And that if you fall into the black hole,

you will come out on the other side, somewhere light years away,

even though it didn't take you any time to traverse that distance.

We call this a wormhole

because it's like a worm eating its way through an apple.

But could the probe survive the journey?

What goes into a singularity may come out somewhere else,

but what comes out is not gonna have much of a relationship

to what went in.

It will be not only spaghettified, but essentially destroyed.

If you want to go somewhere else, take an airplane.

There's another theory that a singularity isn't a wormhole,

it's a white hole.

A white hole is basically a black hole played backward in time.

So a white hole is a singularity

that sort of spits out into the universe

and pushes things away from it rather than pulling them in.

The singularity spits out a universe,

a process bearing a striking similarity to the Big Bang.

Our Big Bang emerged, at least classically, from a singularity.

And it's not lost on people

that the end point of a black hole is a singularity.

Is there a connection between the two? Maybe.

But in reality, scientists are not sure

that this infinitely dense and infinitely small singularity

at the centre of a black hole exists at all.

Infinities popping up in physics

really just tell us that we have no clue what we're talking about.

We've never seen anything actually infinite in physics.

So my own personal guess is that there are no singularities.

And that whenever we see an infinity pop out of our equations,

it's just nature telling us that...

(MIMICS BUZZER) "You were wrong."

Einstein's general relativity commits suicide, if you will,

at singularities.

It can't continue space-time beyond singularities.

How that plays out...

..don't know. We don't know what happens to it.

This is the end of the probe's extraordinary journey.

It has reached the end of space and time

and the limit of human knowledge.

Certainly, right now, black holes are the bad boys of physics.

They break every rule we know,

and that just shows us our own limitations.

It's not the black hole's problem,

we have not gotten far enough to explain them.

And that will continuously challenge us and pull us

in a real way into the heart of a black hole.

On our own journey into the black hole's heart,

we've discovered it's more than the veracious monster of science fiction.

It's a time machine...

..and a cosmic museum...

..a destroyer and a creator of worlds,

and the universe's ultimate enigma.

Understand black holes

and we will truly understand how the universe works.

The math is bizarre, the observations are difficult,

and the concepts are mind-shredding. Who wouldn't love that?

I think a lot of people love black holes

just because they're big and scary and fun.

But we physicists love them also for a different reason,

which is that it's the most extreme physical systems

that usually give us the best clues about how nature works.

Black holes have driven our imagination

beyond where it would have gone before.

Nature is much more imaginative than we are.

And every time we explore nature, we're surprised.

So truth is far stranger than fiction,

and the real universe exceeds

even the wildest imaginings of the wildest science fiction writer.

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