All language subtitles for 8C3F52D0C69DA0E0B238865C4950B297_eng

Must we die?

Are there beings in the
cosmos who live forever,

afloat on an endless journey
down the river of time?

Our ancestors marked the passage of time
by the moon and stars.

But it was the people who once lived here,
around 5,000 years ago, who first started

chopping up time into smaller,
bite-sized portions of hours and minutes.

They call this place Uruk.

We call it Iraq.

It's a part of Mesopotamia.

The land between the Tigris and Euphrates
rivers.

The city was invented here,
and one of humanity's greatest

victories was won in the
ceaseless battle against time.

It was here that we learned how to write.

Death could no longer silence us,
and writing gave us the power to reach

across the millennia and speak inside the
heads of the living.

No one had ever spoken across a longer
stretch of time's river than this city.

This city was the birthplace of Akkadian
princess, daughter of the first emperor in

history, and priestess of the moon,
Enheduanna.

For not only did she write
poetry, but Enheduanna

did something no one
before her had ever done.

She signed her name to her work.

She's the first person for whom we can say
we know who she was, and what she dreamed.

She dreamt of stepping through the gate of
wonder.

Here's a thought Enheduanna sent across
more than 4,000 years.

It was a dream.

It's from her work entitled, Lady of the
Largest Heart.

Enheduanna, the planet
Venus, goddess of love, will

have a great destiny
throughout the entire universe.

And Uruk is also the
place where the epic tale

of the hero's journey
was first written down.

Before Batman, Luke Skywalker,
Odysseus.

Before Superman, Luke Skywalker,
Odysseus.

Before them all, there was
a man named Gilgamesh,

who left home on a
quest to vanquish time.

Gilgamesh was searching for immortality.

He looked everywhere, gained complete
wisdom, uncovered what was hidden.

He brought back a tale of times before the
great flood.

He built the wall of Uruk, which no future
king will ever match.

Read the story of that man, Gilgamesh.

A hero born of Uruk, who went through all
kinds of sufferings.

Who crossed the ocean, the broad seas,
as far as the sunrise.

Who inspected the edges of the world,
searching for eternal life.

On his travels, Gilgamesh encountered a
wise man named Ut-Nan-Pishtim,

who told him the story of a flood that
destroyed the world.

And how one of the gods
instructed Ut-Nan-Pishtim to

build an ark to rescue
his family and the animals.

The earliest surviving account of the
flood legend was written down in

Mesopotamia, a thousand
years before it was

retold as the story of
Noah in the Old Testament.

So you could say Gilgamesh fulfilled his
quest for immortality.

We still read the epic of Gilgamesh,
and with every reader, he lives again.

And all those heroes and superheroes who
have come since...

follow in the footsteps of the first
hero's journey.

Another kind of immortality.

A story sent from one civilization to
another across thousands of years.

But life itself sends its own stories
across billions of years.

It's a message that every one of us
carries inside.

Inscribed in all the cells of our bodies.

In a language that all life on Earth can
read.

The genetic code is written in an alphabet
consisting of only four letters.

Each letter is a molecule made of atoms.

Each word is three letters long.

Every living thing is a masterpiece.

Written by nature and edited by evolution.

The instructions for running and

reproducing the
intricate machinery of life.

The essential message
of life has been copied

and recopied for more
than three billion years.

But where did that message come from?

Nobody knows.

Perhaps it began in a shallow,
sunlit pool just like this.

Somehow, carbon-rich molecules began using
energy to make crude copies of themselves.

Some varieties were better at making
copies and left more offspring.

The competing molecules became more
elaborate.

Evolution and life itself was underway.

Or life could have started somewhere else.

We started in the searing heat of a
volcanic vent on the deep sea floor.

Or is it possible that life came to Earth
as a hitchhiker?

Let me tell you a story about a traveler
from another world.

The peace of the Egyptian
village of Nakhla near Alexandria

was abruptly shattered
on a June morning in 1911.

Written in this meteorite was a message
from another planet.

But 70 years would pass before anyone
could read it.

In 1976, NASA landed two Viking spacecraft
on Mars.

Carl Sagan took us there on our original
journey.

We found that the Martian
air was less than 1% as

dense as ours and made
mostly of carbon dioxide.

There were smaller amounts of nitrogen,
argon, water vapor, and oxygen.

A few years later, when scientists thought
to analyze the gases trapped inside the

Nakhla meteorite and other members of its
class, they found a striking similarity.

The vast majority of meteorites are
fragments of asteroids.

But the kind that hit Nakhla was not.

Nakhla on Earth could only have come from
one place.

Mars.

Welcome to Mars.

Over a billion years ago, a volcano erupted
here and its lava cooled into solid rock.

Hundreds of millions of years later,
this area was flooded with water.

And long after that flood, an asteroid the
size of the Rock of Gibraltar crashed into

the Martian surface, blasting out a huge
crater.

Much of the debris was ejected back out
into space, where it orbited the Sun until

a gravitational tug from its
home planet, Mars, diverted

one of the boulders into a
collision course with Earth.

Its arrival shook up the little village of
Nakhla.

Meteorites of the type that hit Nakhla are
the vehicles of a natural interplanetary

transit system that sends rocks between
the planets.

Such a meteorite can safely shelter
microscopic cargo, the seeds of life,

an interplanetary arc.

Most rocks are porous, full of tiny nooks
and crannies, where life can stow away.

We know that some microbes can survive the
hostile environment of space.

Take these guys, for instance.

These microbes spent a year and a half
riding on the outside of the International

Space Station,
exposed to the extreme

temperatures, vacuum,
and radiation of space.

And some of them
were still alive and

kicking when they were
brought back to Earth.

Even more astonishing are
these creatures, awakened

from a death-like sleep
of eight million years.

They were frozen in
the Antarctic ice millions

of years before our
species even existed.

And they're still alive.

If life can withstand the hardships of
space and endure for millennia,

then it could ride the
natural interplanetary

transit system
from world to world.

It's a good bet that our microbial
ancestors spent some time in space.

Why do we think so?

The Earth is four and a half billion years
old.

For the first half of its
lifetime, large asteroids

were bombarding the
planet every few million years.

The most violent impacts vaporized the
oceans and even melted the surface rock.

Each such collision
would have completely

sterilized the planet
for thousands of years.

But we know from fossils
in the rocks that bacteria

were evolving on Earth
during this formative period.

So how could life have survived such a
lethal series of blows?

Whenever one of those big asteroids hit
the Earth, the explosion would blast out a

crater, launching millions of boulders
into space.

Many of those rocks carried living
bacteria inside.

Some of the bugs would
have survived in space, while

all those left behind on
Earth would have been fried.

A few thousand years after
each impact, the Earth would

have cooled down enough for
water to condense into oceans.

The planet would again be habitable.

Meanwhile, most of the rocks launched into
space would have been orbiting the Sun.

Some of them would encounter the Earth
again, re-enter the atmosphere as

meteorites, and deliver their precious
cargo of life to reseed the planet.

Like Noah's Ark.

What this means is that
life doesn't have to start

over again from scratch
after each catastrophe.

It can pick up where it left off.

When the solar system was young,
Venus was probably more like Earth.

With oceans and maybe even life,
Venus, Earth, and Mars were all exchanging

rocks with each other due to asteroid
impacts.

Does life on Earth
carry any traces of

interplanetary voyages
made in the distant past?

Or is it that some microbes can survive
the intense radiation and vacuum of space?

These conditions don't naturally exist on
Earth.

Maybe those bugs are telling
us that their ancestors survived

those same conditions in
space a few billion years ago.

So we know that microbes
can stow away in rocks

and survive the voyage
from planet to planet.

What about a trip from star to star?

An interstellar odyssey.

The dandelion.

Around 30 million years
ago, it evolved another way to

send its own message of
life through space and time.

Each seedling is a little
paratrooper floating on the

wind, risking everything
for a safe place to land.

Updraft can carry them higher into the
air.

A dandelion can travel dozens,
possibly hundreds of kilometers,

even crossing over mountain ranges.

Evolution has shaped it into an exquisite
flying machine.

The seed is another kind of ark,
ensuring the survival of its species by

riding the currents of the atmosphere to
safe harbors.

Each seed in its DNA
carries a story, the

character and destiny
of the next dandelion.

Life propagates.

It propagates by retelling its story.

Is it possible that life could survive the
journey from star to star?

The stars are about a million times farther
apart from each other than are the planets.

Space is so vast that it would take
billions of years for a rock ejected from

the Earth to collide with a planet
circling another star.

Any stowaway microbes would never survive
the cosmic radiation for that long.

But there's a plausible
scenario for how life

could spread from one
solar system to another.

The stars of the Milky
Way are drawn by gravity

in their own enormous
orbits around its center.

Our Sun, for example, takes some 225
million years to complete a single orbit.

During each revolution around
the galaxy, our solar system

will pass through two or three
gigantic interstellar clouds.

Each of them many light years across.

Galaxies are world-making machines.

Our Milky Way has more than a hundred of
these vast clouds, places where gas and

dust condense to form new stars and
planets.

In its travels through the Milky Way,
our Sun is accompanied not only by its

planets, but also by a trillion distant
comets.

When our solar system passes through an
interstellar cloud, the gravity of the

massive cloud stirs up the outermost
comets.

Some comets will be hurled out into the
space between the stars.

Others will plunge inward,

falling towards the Sun.

And some of them may collide with the
planets.

The high-speed impact
of a comet with a rocky

planet will launch boulders
like rockets into space.

If that planet should happen
to be inhabited, many of

those rocks will carry
passengers, living microbes.

After thousands of years, fragments of the
rocks ejected from Earth can fall as

meteors into the atmospheres of newborn
planets in the interstellar cloud.

If the stowaway microbes should happen to
come in contact with liquid water,

they can revive and reproduce.

This may be how life comes barreling into
the barren places.

The Sun emerges from the
cloud, having scattered the

seeds of life among the
newborn worlds of other stars.

Those new worlds, now
touched by life, will then

leave their birth cloud
and go their separate ways.

Eventually, their stars will
carry them through other

interstellar clouds, where they
may seed still more new worlds.

Imagine this process repeated from world
to world, each one bringing life to others.

Life would then propagate like a slow
chain reaction through the entire galaxy.

This could be how life came to Earth.

We do not know for sure.

Are there any beings out there like us?

Do they ask the same questions?

Do they share our fears?

Do they have heroes and adventures?

If they do exist, where are they?

How might they make their presence known?

How did we first announce our presence to
the galaxy?

It was 1946, the year after the Second
World War ended.

The vivid imaginations of H.G.

Wells and Buck Rogers never cooked up a
more fantastic experience than the Army

engineers at their laboratory in Belmar,
New Jersey.

It opens up unlimited possibilities for
interstellar experiment.

American engineers
bounced a beam of radio waves

off the Moon and were
able to detect its echo.

They called this experiment Project Diana.

It was the first interstellar message.

Ever sent by our species.

An eerie tolling bell.

If one allows the imagination free rein,
many future possibilities appear.

Space ships carrying passengers at
thousands of miles per hour can be

controlled and communication established
with their passengers.

For we now know that the Earth's
atmosphere can be penetrated.

Traveling at the speed
of light, it takes just over

one second for a radio wave
to reach the lunar surface.

But the expanding wavefront is much bigger
than the Moon.

Most of the wave passes right by it,
but the central part gets bounced back.

After a round-trip travel time of two and
a half seconds, it hits our planet.

Project Diana transmitted
a series of powerful radio

waves, one every four
seconds, to ping the Moon.

The parts that miss the Moon are
travelling still.

It was just the beginning.

After World War II, television
stations cropped up all

over the United States
and other parts of the world.

The Project Diana message and the FM
radio, television and radar signals of the

20th century all move outward at the speed
of light.

These transmissions make
up a vast sphere of radio

waves expanding away
from the Earth in all directions.

You could say that our world is radiating
stories.

Our ancestors etched
the story of Gilgamesh into

clay tablets, sending that
epic tale into the future.

We've encoded our stories in radio waves
and beamed them into space.

They cover one light-year
of distance, that's six trillion

miles, for every year of
time since they were sent.

We've been sending our stories into space
for over 70 years.

The leading edge of
these signals has already

washed over thousands
of planets of other stars.

If any of these worlds are home to a
civilization with radio telescopes,

they could already know that we're here.

What if other worlds are sending their
stories into space?

Since 1960, we've been listening for
extraterrestrial radio waves and radio

signals without hearing so much as a
tolling bell.

But our search has been sporadic and
limited to certain parts of the sky.

For all we know, we may
have just missed an alien

signal, looking in the wrong
place at the wrong time.

We've only listened to a miniscule
fraction of the stars in our galaxy.

And there may be another problem.

We are, to some extent,
prisoners of our own

moment in time with the
limits of our technology.

Our television broadcasting
may be only a brief

passing phase in our
technological development.

When we imagine alien civilizations
broadcasting signals with radio

telescopes, are we any
different from earlier generations

who imagined riding
cannon shells to the moon?

Civilizations even slightly more advanced
than ours may have already moved on to

some other mode of communication, one that
we have yet to discover or even imagine.

Our senses could be
swirling all around us at this

very moment, but we lack
the means to perceive them.

Just as all of our ancestors up to a
little more than a century ago would have

been oblivious to the most urgent radio
signal from another world.

But there's another, more troubling
possibility.

Civilizations, like other living things,
may only live so long before perishing due

to natural causes or violence or
self-inflicted wounds.

But their impact with intelligent alien
life may depend on a critical question.

What is the life expectancy of a
civilization?

By the time of Enheduanna, the first
person to ever get a writing credit,

civilization was already more than a
thousand years old.

But today, her glorious city is a barren
wasteland.

What went wrong?

One problem was the almost ceaseless
warfare between the cities of Mesopotamia,

which continually destroyed their
achievements.

They glorified military conquest and
ultimately became its victims.

Another cause of decline
was that their technical

know-how overran their
understanding of nature.

The ingenious irrigation system
that was the basis for the great

civilizations of Mesopotamia
had an unintended consequence.

The water channeled
into their farmlands every

year evaporated
and left its salt behind.

Over generations, the salt accumulated and
began to kill the crops.

And then, about 2200 BC, not long after
the time of Enheduanna, disaster struck.

A drought of truly epic proportions
lasting for many decades.

The rains stopped.

Crops withered.

There was famine and anarchy.

Barbarians invaded.

The streets of many cities were littered
with dead.

There could be only one explanation.

Enlil, the supreme god, was angry.

Because one of his temples had been
destroyed.

The people of Mesopotamia could not know
that the same drought was crushing the

dawning civilizations of Egypt,
Greece, India, Pakistan and China.

All the gods of the earth must have been
really angry about something.

For all their brilliance, the
people of those civilizations

had no inkling they were
experiencing abrupt climate change.

Three thousand years
later, the climate would

change abruptly for
another glorious civilization.

This one in Central America.

At its peak, the Mayan civilization
perished.

Wiped out by a series of severe droughts
over the course of a century.

We still carry within us
the echoes of these extinct

civilizations in our
languages, in our myths.

Today, we have a single global
civilization.

How long will it live?

There are so many ways for a civilization
to die.

Let's start with the ones that we probably
wouldn't be able to live without.

We wouldn't be able to do much about.

That supernova is a thousand light years
away.

If it were much closer, say, less than 30
light years from earth, its cosmic

radiation would shred
the atmosphere's protective

ozone layer and
destroy our civilization.

Lucky for us, none of the stars close
enough to harm us are likely to go

supernova any time in the next few hundred
million years.

Every million years or so, a supervolcano
erupts somewhere on earth.

The last time it happened
was 74,000 years ago on

the island of Sumatra
in what is now Indonesia.

It spewed hundreds of times
more rock, ash, and toxic

gas than any single
volcano in recorded history.

The molten rock that erupted
from earth's crust left this

caldera, 100 kilometers
long, now filled with a lake.

The Toba volcano sent more than 600 cubic
miles of pulverized rock soaring skyward.

The westward wind carried
the volcanic ash over India where

it fell out in a smothering
blanket over the subcontinent.

The eruption loaded the upper atmosphere
with sulfur gases.

The result was a global
haze that blocked most of the

sunlight from reaching the
surface for at least five years.

It was like one five-year-long cloudy day.

This so-called volcanic winter resembled a
nuclear winter but without the radiation.

Temperatures fell everywhere.

Plants and animals froze even in the
tropics, dying in enormous numbers.

But life is hardy.

Only a few species were driven to
extinction.

One of our ancestors in
central India sharpened this

stone blade in the years
before the Toba eruption.

And this blade was one
of dozens that were found

in the soil layer above
the volcanic fallout.

This tells us that some
toolmakers, even in the area directly

affected by the volcano,
managed to survive the cataclysm.

But the global human population must have
plummeted before rebounding.

If an eruption like this were to happen
tomorrow, our civilization would be

brought to its knees, although the human
species would survive.

I can imagine that our technology of a few
hundred years from now would allow us to

siphon off the energy of a threatening
supervolcano before it explodes.

We could then use that energy for our own
purposes.

About once every million years,
a small asteroid collides with the Earth,

causing a similar amount of devastation.

With our current science
and technology, we

already know how to
prevent an asteroid impact.

We would see it coming
years in advance and

could send a spacecraft
there to deflect it.

Into a harmless orbit.

With the technology of a thousand years
from now, we might even be able to

mitigate the deadly effects of a nearby
supernova on Earth's atmosphere.

But what happens when the danger to a
civilization is invisible?

When no one can see it coming?

Beginning with Columbus, the
European invaders of the Americas

had a secret weapon that
even they knew nothing about.

They were carrying bacteria and viruses
for deadly diseases such as smallpox that

the original Americans had never been
exposed to.

The Europeans liked to
believe that it was their valor and

superior weapons and culture
that won them the New World.

The real conquistadors were the armies of
the pathogens that raced on ahead to

infect and kill nine
out of ten of all the

Indians of North, Central
and South America.

The great civilizations of
the New World crumbled

under the onslaught
of invading microbes.

Without his invisible
army, Cortes and those

who followed might
never have stood a chance.

But what about civilizations that
self-destruct?

Our economic systems were formed when the
planet and its air, rivers, oceans,

lands all seemed infinite.

They evolved long
before we first saw the

Earth as the tiny
organism that it actually is.

They're all alike in one respect.

They are profit-driven, and therefore
focused on short-term gain.

The prevailing economic systems,
no matter what their ideologies,

have no built-in mechanisms
for protecting our descendants of

even a hundred years from
now, let alone a hundred thousand.

In one respect, we're ahead of the people
of ancient Mesopotamia.

Unlike them, we understand what's
happening to our world.

For example, we're pumping
greenhouse gases into our

atmosphere at a rate not seen
on Earth for a million years.

And there's scientific consensus that
we're destabilizing our climate.

Yet, our civilization seems to be in the
grip of denial.

A kind of paralysis.

There's a disconnect between what we know
and what we do.

Being able to adapt our
behavior to challenges is

as good a definition of
intelligence as any I know.

If our greater intelligence is the
hallmark of our species, then we should

use it, as all other beings use their
distinctive advantages, to help ensure

that their offspring prosper
and their heredity is passed on,

and that the fabric of nature
that sustains us is protected.

Human intelligence is imperfect,
surely, and newly arisen.

The ease with which it can be
sweet-talked, overwhelmed or subverted by

other hard-wired tendencies,
sometimes themselves

disguised as the light
of reason, is worrisome.

But if our intelligence is the only edge,
we must learn to use it better.

To sharpen it.

To understand its limitations and
deficiencies.

To use it as cats use stealth before
pouncing.

As walking sticks use camouflage.

To make it the tool of our survival.

If we do this, we can solve
almost any problem we are

likely to confront in the
next hundred thousand years.

And now we've arrived at
the place where our ancient

dreams of immortality and
modern astrophysics converge.

Giant elliptical galaxies,
or something like Florida,

where the oldest stars in
the universe may be found.

This is a red dwarf star, smaller and
fainter than our sun.

Red dwarfs are by far the most plentiful
stars in the cosmos.

Unlike the sun, which is halfway through
its ten billion year lifetime,

red dwarfs will continue
to provide light and

warmth to their planets
for trillions of years.

That's hundreds of times longer than the
present age of the universe.

What would intelligent
beings do if they had an

eternity to develop their
understanding of the universe?

Perhaps they would learn how to open
shortcuts in the fabric of space-time.

To travel between galaxies faster than the
speed of light.

Maybe they would create whole new universes
as artistic or scientific experiments.

Of course, no one, or at least nobody on
Earth, knows what the immortals might do.

If one allows the imagination free
reign...

But what about us?

What is our own future?

What would the cosmic calendar of the next
14 billion years look like?

If the original cosmic calendar includes
all of the time from the birth of the

universe until this very
moment, what would the cosmic

calendar look like for
the next 14 billion years?

Just as with the cosmic
calendar of the past, every month

on the future calendar
equals about a billion years.

Every day, some 40 million.

Science makes it possible
for us to foretell certain

astronomical events in the
unimaginably distant future.

The death of the sun, for example.

In some 5 billion years, our
star will have exhausted its

hydrogen, the nuclear fuel that
powers it, becoming a red giant.

I know that sounds depressing,
but if we apply our intelligence,

our descendants of that
distant future will have

long departed from the
lost worlds of the sun.

Who knows?

Human events entail too
many variables, too many

uncertainties to make scientific
statements about our future.

But we can still dream.

The next golden age of human achievement
begins here and now.

New Year's Day of the next cosmic year.

In the first tenth of a second,
we take the vision of the pale blue dot to

heart and learn how to share this tiny
world with each other.

The last internal combustion
engine is placed in a museum

as the effects of climate
change reverse and diminish.

A fifth of a second
into this future, people

will stop dying from
the effects of poverty.

The planet is now a completely

self-sustaining,
intercommunicating organism.

A half second from now,
the polar ice caps are

restored to the way they
were in the 19th century.

And the forecast is mild and pleasant for
the next cosmic minute and a half,

40,000 years.

By the time we are ready to settle even
the nearest other planetary systems,

we will have changed.

The simple passage of so many generations
will have changed us.

Necessity will have changed us.

We are an adaptable species.

It will not be we who reach
Alpha Centauri and the

other nearby star systems
on our interstellar arcs.

It will be a species very
like us, but with more

of our strengths and
fewer of our weaknesses.

More confident, far-seeing, capable and
wise.

For all our failings,
despite our flaws and

limitations, we humans
are capable of greatness.

What new wonders
undreamt of in our time will

we have accomplished
in another generation?

How far will our nomadic
species have wandered by

the end of the next century
and the next millennium?

Our remote descendants, safely arrayed on
many worlds throughout the solar system

and beyond, will be unified by their
common heritage, by their regard for their

home planet, and by the knowledge that
whatever other life there may be,

the only humans in all the universe came
from Earth.

They will gaze up, and strain to find the
blue dot in their skies.

They will marvel, at how vulnerable the
repository of all our potential once was,

how perilous our infancy,
how humble our beginnings,

how many rivers we had to
cross before we found our way.