Original subtitles

The Holocene has ended.

What we do now, and in the next few years, will profoundly affect

the next few thousand years.

The only conditions modern humans have ever known so far are changing, and

changing fast.

Nothing stays the same on this planet.

Everything changes.

The Earth is going into one of these jumps, and you don't know what is going

to be on the other side of those jumps.

The Earth is always jumping.

Things move on this planet.

Things are not still.

Everything is turning.

As it begins to run out of fuel, the sun won't simply fade away to nothing.

Its core will collapse, and the extra heat this generates will cause its outer

layers to expand.

The sun is now dead.

It's remained slowly cooling.

in the freezing temperatures of deep space.

The fate of the sun is the same as for all stars.

One day they must all eventually die and the cosmos will be plunged into eternal

night.

All stars?

eventually will run out of fuel the temperature of the universe drops the

stars one by one in the night sky will turn off

and there'll be no more new stars created

and so that the universe will end not with a bang but with a

whimper and not in fire but in ice

With no fuel left to burn a white dwarfs faint glow comes from the last residual

heat from its extinguished furnace

Looking at it from where the

earth is now It would only generate the same amount of light as the full moon on

a clear night

The faint glow of white dwarves will provide the only illumination in a dark

and empty void, littered with dead stars and black holes.

In some ways it's kind of a ghost universe.

It's the corpses, the zombie stars, that will take us into the future.

A black dwarf will be the final fate of those last stars.

White dwarfs that have become so cold that they barely emit any more heat or

light.

Black dwarfs are dark, dense, decaying balls of degenerate matter.

Little more than the ashes of stars.

Their constituent atoms are so severely crushed that black dwarves are a million

times denser than our sun.

Stars take so long to reach this point, we believe there are currently no black

dwarves in the universe.

We have a pace of life that's based on really the energy available to us now.

You could imagine living conscious systems which have a very different pace

and therefore can extend out at least a lot farther than you'd imagine

otherwise.

You could have a living system where if it had a thought every 10 trillion

years, that would seem normal.

Even if our life dies out, One could imagine, at some time arbitrarily far in

the future, a fluctuation occurs which allows intelligent life to exist again

for a little while.

So you might have islands in time of intelligence.

A proton, one of the fundamental building blocks of atomic matter, what

makes us up, can just spontaneously fall apart.

Any material that evades the pull of a black hole eventually dies away as its

protons disintegrate.

The matter inside black dwarfs, the last matter in the universe, will eventually

evaporate away and be carried off into the void as radiation, leaving

absolutely nothing behind.

With the black dwarfs gone, there won't be a single atom of matter left.

All that will remain of our once rich cosmos will be particles of light and

black holes.

The arrow of time creates a bright window in the universe's adolescence

during which life is possible.

But it's a window that doesn't stay open for long.

As a fraction of the lifespan of the universe, as measured from its beginning

to the evaporation of the last black hole, life as we know it is only

possible for one thousandth of a billion billion billionth billion billion

billion billion billion billion billionth of a percent.

Black holes become the fundamental building block of the universe.

A galaxy will basically be a supermassive black hole in the center

with smaller black holes orbiting it.

Zombie galaxies filled with black holes continue to evolve.

They'll eat each other and they'll get bigger and maybe they'll fall into the

supermassive black hole and it'll get bigger. The universe will still be an

exciting, dynamic place.

It's just that the timescales you're talking about are now trillions of years

instead of thousands or millions of years.

Black holes can bang on space-time like mallets on a drum.

And they have a very characteristic song.

Imagine two black holes that have lived a long life together.

At the end of their lives, they're going around each other, crossing thousands of

kilometers in a fraction of a second.

As they do so, they leave behind in their wake a ringing of space, an actual

wave on spacetime.

Space squeezes and stretches as it emanates out from these black holes

banging on the universe.

Those are the gravitational waves. They are literally the sounds of space

ringing, and they will travel out from these black holes at the speed of light

as they ring down and coalesce to one spinning, quiet black hole.

If you were standing near enough, your ear would resonate with the squeezing

and stretching of space.

You would literally hear the sound.

Imagine a lighter black hole falling into a very heavy black hole. The sound

you're hearing is a light black hole banging on space each time it gets

close.

As it falls in, it gets faster and it gets louder.

Scientists used to think black holes were immortal.

But even these will one day die.

Now we're talking about timescales of unimaginable length, quadrillions of

years into the future.

On that timescale, even the black holes begin to evaporate.

According to quantum mechanics, Space is filled with virtual particles and anti

-particles that are constantly materializing in pairs, separating,

coming together again, and annihilating each other.

In the presence of a black hole, one member of a pair of virtual particles

may fall into the hole.

leaving the other member without a partner with which to annihilate.

The forsaken particle appears to be radiation emitted by the black hole.

And so, black holes are not eternal.

They evaporate away at an increasing rate until they vanish.

in a gigantic explosion.

Quantum mechanics has allowed particles and radiation to escape from the

ultimate prison, a black hole.

Philosophers and poets have asked the question, will the world end in fire or

ice?

We can now give an answer.

The latest evidence shows that the universe is not slowing down, but it's

speeding up out of control.

And the universe, we think, will die in ice.

Trillions upon trillions of years from now.

Empty space itself.

has energy. In every little cubic centimeter of space, whether or not

there's stuff, whether or not there's particles, matter, radiation, or

whatever, there is still energy even in the space itself.

And this energy, according to Einstein, exerts a push on the universe.

What is the weird stuff that's accelerating the universe?

We call it dark energy.

And this stuff is the dominant stuff of the universe.

Almost three-quarters of the matter-energy content of the universe is

this dark energy.

And we don't know what it is.

Dark energy, unlike matter or radiation, does not dilute away as the universe

expands.

This has crucial implications for what the universe is going to do in the

future.

So what will be the future of the universe?

Well, if the dark energy remains dominant and repulsive, the universe

will expand forever.

Faster and faster and faster with time.

A runaway universe.

70% of the energy of the universe resides in empty space.

And we don't understand why.

But we do know what will happen.

If that energy continues to be there, the universe will become cold and dark

and empty.

That's the future as it might be.

We don't know.

Because we don't yet understand the nature of dark energy. Until we do, we

won't know the future. We won't even understand our own origins. And that's

why we want to know and study this subject.

The forecast does seem to be for an ever-colder, ever-emptier universe.

But then of course we have to ask, could that end lead to a new beginning?

And there are ideas whereby what actually is the end of our universe

could in some sense be linked to the beginning of a new one.

We've worked out the mathematics, the equations. They seem to say that if you

have an atom smasher that can concentrate tremendous amounts of energy

at a single point, you can perhaps open up a gateway, a baby universe.

Facing the death of everything there is, this perhaps is their only possibility

of escape.

And this also raises a very intriguing possibility, sheer speculation of

course, that perhaps any universe that has intelligent life in it will create

baby universes, will create lifeboats, and proliferate child universes.

So an evolution may take among universes in the multiverse.

Survival of the fittest may take place.

So those universes which do not have intelligent life are infertile. They

have no children.

But those universes that have mild temperatures, stars like us, would

create civilizations that could open up child universes, and they would then

proliferate.

After an unimaginable length of time, even the black holes will have

evaporated and the universe will be nothing but a sea of photons gradually

tending towards the same temperature as the expansion of the universe cools them

towards absolute zero.

Once the very last remnants of the very last stars have finally decayed away to

nothing, and everything reaches the same temperature, the story of the universe

finally comes to an end.

For the first time in its life, the universe will be permanent and

unchanging.

Entropy finally stops increasing because the cosmos cannot get any more

disordered. Nothing happens and it keeps not happening forever.