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Must we die?
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Are there beings in the cosmos
who live forever...
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afloat on an endless journey
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down the river of time?
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Our ancestors
marked the passage of time
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by the Moon and stars.
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But it was the people
who once lived here,
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around 5,000 years ago,
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who first starting
chopping up time
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into smaller bite-sized portions
of hours and minutes.
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They call this place Uruk.
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We call it Iraq.
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It's a part of Mesopotamia,
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the land between the Tigris
and the Euphrates rivers.
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The city was invented here.
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And one of humanity's
greatest victories was won
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in the ceaseless battle
against time.
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It was here that we learned
how to write.
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Death could
no longer silence us.
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And writing gave us the power
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to reach across the millennia
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and speak inside the heads
of the living.
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No one has ever spoken
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across a longer stretch
of time's river
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than this Akkadian princess,
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daughter of the first emperor
in history,
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and priestess of the Moon--
Enheduanna.
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For not only
did she write poetry,
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but Enheduanna did something
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no one before her
had ever done--
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she signed her name
to her work.
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She's the first person
for whom we can say
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we know who she was,
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and what she dreamed.
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She dreamt of stepping
through the Gate of Wonder.
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Here's a thought
Enheduanna sent
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across more than 4,000 years
to you.
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It's from her work entitled
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Lady of the Largest Heart.
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Innana, the planet Venus,
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goddess of love,
will have a great destiny
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throughout the entire universe.
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...throughout
the entire universe.
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And Uruk is also the place
where the epic tale
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of "The Hero's Journey"
was first written down.
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Before Batman, Luke Skywalker,
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Odysseus-- before them all--
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there was a man named Gilgamesh
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who left home on a quest
to vanquish time.
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Gilgamesh was searching
for immortality.
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He looked everywhere,
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gained complete wisdom,
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uncovered what was hidden.
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He brought back a tale of times
before the Great Flood.
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He built the Wall of Uruk,
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which no future king
will ever match.
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Read the story
of that man Gilgamesh,
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a hero born of Uruk,
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who went through all kinds
of sufferings.
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Who crossed the ocean,
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the broad seas,
as far as the sunrise;
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who inspected
the edges of the world,
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searching for eternal life.
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On his travels,
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Gilgamesh encountered
a wise man named Utnapishtim,
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who told him the story of a
flood that destroyed the world,
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and how one of the gods
instructed Utnapishtim
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to build an ark to rescue
his family and the animals.
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The earliest surviving account
of the flood legend
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was written down in Mesopotamia,
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a thousand years
before it was retold
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as the story of Noah
in the Old Testament.
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So, you could say Gilgamesh
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fulfilled his quest
for immortality.
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We still read
the Epic of Gilgamesh,
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and with every reader,
he lives again.
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And all those heroes and
superheroes who have come since
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follow in the footsteps
of the first hero's journey--
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another kind of immortality;
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a story sent from one
civilization to another
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across thousands of years.
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But life itself sends
its own stories
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across billions of years.
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It's a message that every
one of us carries inside,
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inscribed in all the cells
of our bodies,
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in a language that all life
on Earth can read.
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The genetic code
is written in an alphabet
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consisting of only four letters.
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Each letter is
a molecule made of atoms;
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each word is three letters long.
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Every living thing is
a masterpiece,
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written by nature
and edited by evolution;
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the instructions
for running and reproducing
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the intricate machinery of life.
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The essential message of life
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has been copied and recopied
for more than 3 billion years.
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But where did
that message come from?
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Nobody knows.
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Perhaps it began in a shallow,
sunlit pool, just like this.
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Somehow, carbon-rich molecules
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began using energy to make
crude copies of themselves.
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Some varieties were
better at making copies,
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and left more offspring.
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The competing molecules
became more elaborate.
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Evolution and life itself
was underway.
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Or life could've started
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in the searing heat
of a volcanic vent
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on the deep sea floor.
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Or is it possible
that life came to Earth
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as a hitchhiker?
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Let me tell you a story
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about a traveler
from another world.
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The peace of the Egyptian
village of Nakhla,
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near Alexandria,
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was abruptly shattered
on a June morning in 1911.
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Written in this meteorite was
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a message from another planet.
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But 70 years would pass
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before anyone could read it.
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In 1976,
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NASA landed two Viking
spacecraft on Mars.
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Carl Sagan took us there
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on our original journey
through the cosmos.
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We found that the Martian air
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was less than one percent
as dense as ours,
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and made mostly
of carbon dioxide.
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There were smaller amounts
of nitrogen,
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argon, water vapor and oxygen.
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A few years later,
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when scientists thought
to analyze the gasses
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trapped inside
the Nakhla meteorite,
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and other members of its class,
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they found
a striking similarity--
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the vast majority of meteorites
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are fragments of asteroids.
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But the kind
that hit Nakhla, on Earth,
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could only have come
from one place...
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Mars.
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Welcome to Mars.
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Over a billion years ago,
a volcano erupted here
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and its lava cooled
into solid rock.
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Hundreds of millions
of years later,
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this area was flooded
with water.
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And long after that flood,
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an asteroid the size of
the Rock of Gibraltar
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crashed into
the Martian surface,
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blasting out a huge crater.
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Much of the debris was ejected
back out into space,
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where it orbited the Sun
until a gravitational tug
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from its home planet, Mars,
diverted one of the boulders
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into a collision course
with Earth.
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Its arrival shook up
the little village of Nakhla.
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Meteorites of the type that
hit Nakhla
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are the vehicles of a natural
interplanetary transit system
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that sends rocks between
the planets.
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Such a meteorite can safely
shelter microscopic cargo--
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the seeds of life--
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an interplanetary ark.
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Most rocks are porous, full of
tiny nooks and crannies,
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where life can stow away.
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We know
that some microbes can survive
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the hostile environment
of space.
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Take these guys, for instance.
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These microbes spent a year
and a half riding
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on the outside of the
International Space Station,
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exposed to the extreme
temperatures, vacuum,
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and radiation of space.
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And some of them
were still alive and kicking
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when they were brought back
to Earth.
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Even more astonishing
are these creatures,
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awakened from a deathlike sleep
of eight million years.
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They were frozen
in the Antarctic ice
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millions of years before
our species even existed.
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And they're still alive.
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If life can withstand
the hardships of space
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and endure for millennia,
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then it could ride the natural
interplanetary transit system
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from world to world.
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It's a good bet
that our microbial ancestors
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spent some time in space.
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Why do we think so?
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The Earth is four-and-a-half-
billion-years old.
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For the first half
of its lifetime,
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large asteroids were bombarding
the planet
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every few million years.
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The most violent impacts
vaporized the oceans
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and even melted
the surface rock.
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Each such collision would have
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completely sterilized
the planet
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for thousands of years.
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But we know from fossils
in the rocks
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that bacteria were evolving
on Earth
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during this formative period.
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So how could life have survived
such a lethal series of blows?
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Whenever one
of those big asteroids
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hit the Earth, the explosion
would blast out a crater,
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launching millions of boulders
into space.
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Many of those rocks carried
living bacteria inside.
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Some of the bugs would have
survived in space,
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while all those left behind
on Earth would have been fried.
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A few thousand years
after each impact,
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the Earth would have
cooled down enough
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for water to condense
into oceans.
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The planet would again be
habitable.
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Meanwhile, most of the rocks
launched into space
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would have been orbiting
the Sun.
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Some of them would encounter
the Earth again,
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reenter the atmosphere
as meteorites,
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and deliver their precious
cargo of life
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to re-seed the planet...
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like Noah's ark.
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What this means is that life
doesn't have
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to start over again from
scratch after each catastrophe.
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It can pick up
where it left off.
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00:14:06,052 --> 00:14:08,219
When the solar system was young,
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Venus was probably more
like Earth,
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with oceans and maybe even life.
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00:14:13,626 --> 00:14:16,895
Venus, Earth, and Mars
were all exchanging rocks
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with each other,
due to asteroid impacts.
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Does life on Earth carry
any traces
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of interplanetary voyages
made in the distant past?
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Why is it
that some microbes can survive
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00:14:28,040 --> 00:14:31,409
the intense radiation
and vacuum of space?
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These conditions don't naturally
exist on Earth.
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Maybe those bugs are telling us
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00:14:36,715 --> 00:14:40,919
that their ancestors survived
those same conditions in space,
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a few billion years ago.
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00:14:44,290 --> 00:14:46,758
So we know that microbes
can stow away in rocks
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and survive the voyage
from planet to planet.
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But what about trip
from star to star--
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an interstellar odyssey?
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The dandelion.
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00:15:04,465 --> 00:15:06,899
Around 30 million years ago,
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00:15:06,934 --> 00:15:10,436
it evolved another way to send
its own message of life
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through space and time.
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00:15:20,547 --> 00:15:23,583
Each seedling
is a little paratrooper,
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floating on the wind,
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risking everything
for a safe place to land.
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Updrafts can carry them
higher into the air.
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A dandelion can travel dozens,
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possibly hundreds
of kilometers,
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even crossing over
mountain ranges.
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Evolution has shaped it into
an exquisite flying machine.
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The seed is another kind or ark,
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00:15:49,243 --> 00:15:51,110
ensuring the survival
of its species
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00:15:51,145 --> 00:15:54,614
by riding the currents of the
atmosphere to safe harbors.
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Each seed
in its DNA carries a story,
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00:15:58,018 --> 00:16:01,187
the character and destiny
of the next dandelion--
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00:16:01,221 --> 00:16:04,991
life propagates
by retelling its story.
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00:16:06,927 --> 00:16:10,296
Is it possible that life
could survive the journey
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00:16:10,330 --> 00:16:12,298
from star to star?
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00:16:12,332 --> 00:16:15,168
The stars are about
a million times farther apart
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00:16:15,202 --> 00:16:17,737
from each other
than are the planets.
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00:16:17,771 --> 00:16:21,674
Space is so vast that it would
take billions of years
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00:16:21,709 --> 00:16:23,543
for a rock ejected
from the Earth
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00:16:23,577 --> 00:16:28,314
to collide with a planet
circling another star.
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00:16:28,349 --> 00:16:31,317
Any stowaway microbes
would never survive
258
00:16:31,352 --> 00:16:33,653
the cosmic radiation
for that long.
259
00:16:33,687 --> 00:16:35,555
But there's a plausible scenario
260
00:16:35,589 --> 00:16:39,392
for how life could spread from
one solar system to another.
261
00:16:45,132 --> 00:16:47,500
The stars of the Milky Way
are drawn by gravity
262
00:16:47,534 --> 00:16:51,738
in their own enormous orbits
around its center.
263
00:16:51,772 --> 00:16:53,673
Our Sun, for example,
264
00:16:53,707 --> 00:16:58,378
takes some 225 million years
to complete a single orbit.
265
00:16:58,412 --> 00:17:01,614
During each revolution around
the galaxy,
266
00:17:01,649 --> 00:17:04,617
our solar system will
pass through two or three
267
00:17:04,652 --> 00:17:07,053
gigantic interstellar clouds,
268
00:17:07,087 --> 00:17:10,757
each of them
many light years across.
269
00:17:14,294 --> 00:17:18,531
Galaxies are
world-making machines.
270
00:17:18,565 --> 00:17:22,201
Our Milky Way has more than
100 of these vast clouds,
271
00:17:22,236 --> 00:17:24,804
a place where gas and dust
condense
272
00:17:24,838 --> 00:17:27,473
to form new stars and planets.
273
00:17:30,844 --> 00:17:33,146
In its travels
through the Milky Way,
274
00:17:33,180 --> 00:17:36,149
our Sun is accompanied not only
by its planets,
275
00:17:36,183 --> 00:17:39,686
but also by
a trillion distant comets.
276
00:17:41,655 --> 00:17:44,958
When our solar system passes
through an interstellar cloud,
277
00:17:44,992 --> 00:17:47,260
the gravity of
the massive cloud
278
00:17:47,294 --> 00:17:50,964
stirs up the outermost comets.
279
00:17:50,998 --> 00:17:53,766
Some comets will be hurled out
280
00:17:53,801 --> 00:17:56,336
into the space
between the stars.
281
00:17:58,339 --> 00:18:00,773
Others will plunge inward...
282
00:18:03,143 --> 00:18:05,645
falling towards the Sun.
283
00:18:21,629 --> 00:18:24,831
And some of them may collide
with the planets.
284
00:18:26,400 --> 00:18:29,936
The high-speed impact
of a comet with a rocky planet
285
00:18:29,970 --> 00:18:33,373
will launch boulders
like rockets into space.
286
00:18:33,407 --> 00:18:36,276
If that planet should
happen to be inhabited,
287
00:18:36,310 --> 00:18:38,978
many of those rocks
will carry passengers--
288
00:18:39,013 --> 00:18:41,314
living microbes.
289
00:18:41,348 --> 00:18:43,283
After thousands of years,
290
00:18:43,317 --> 00:18:45,618
fragments of the rocks
ejected from Earth
291
00:18:45,653 --> 00:18:50,056
can fall as meteors into the
atmospheres of newborn planets
292
00:18:50,090 --> 00:18:52,325
in the interstellar cloud.
293
00:18:59,266 --> 00:19:00,833
If the stowaway microbes
294
00:19:00,868 --> 00:19:03,703
should happen to come
in contact with liquid water,
295
00:19:03,737 --> 00:19:07,307
they can revive and reproduce.
296
00:19:07,341 --> 00:19:09,976
This may be
how life comes barreling
297
00:19:10,010 --> 00:19:12,345
into the barren places.
298
00:19:12,379 --> 00:19:14,881
The sun emerges from the cloud,
299
00:19:14,915 --> 00:19:16,516
having scattered
the seeds of life
300
00:19:16,550 --> 00:19:20,153
among the newborn worlds
of other stars.
301
00:19:20,187 --> 00:19:23,223
Those new worlds,
now touched by life,
302
00:19:23,257 --> 00:19:24,824
will then leave
their birth cloud
303
00:19:24,858 --> 00:19:27,026
and go their separate ways.
304
00:19:27,061 --> 00:19:29,495
Eventually, their stars
will carry them
305
00:19:29,530 --> 00:19:30,930
through
other interstellar clouds,
306
00:19:30,965 --> 00:19:34,767
where they may seed
still more new worlds.
307
00:19:34,802 --> 00:19:40,240
Imagine this process
repeated from world to world,
308
00:19:40,274 --> 00:19:43,443
each one bringing life
to others.
309
00:19:49,450 --> 00:19:53,419
Life would then propagate,
like a slow chain reaction,
310
00:19:53,454 --> 00:19:55,788
through the entire galaxy.
311
00:20:00,461 --> 00:20:04,464
This could be
how life came to Earth.
312
00:20:04,498 --> 00:20:06,466
We do not know for sure.
313
00:20:06,500 --> 00:20:10,136
Are there any beings
out there like us?
314
00:20:10,170 --> 00:20:12,105
Do they ask the same questions?
315
00:20:12,139 --> 00:20:13,806
Do they share our fears?
316
00:20:15,142 --> 00:20:16,776
Do they have heroes
and adventures?
317
00:20:22,149 --> 00:20:25,985
If they do exist,
where are they?
318
00:20:26,020 --> 00:20:28,521
How might they make
their presence known?
319
00:20:44,638 --> 00:20:47,974
How did we first announce
our presence to the galaxy?
320
00:20:48,008 --> 00:20:53,680
It was 1946, the year after
the Second World War ended.
321
00:20:56,283 --> 00:20:58,284
The vivid imaginations
322
00:20:58,319 --> 00:21:00,119
of HG Wells and Buck Rogers
323
00:21:00,154 --> 00:21:02,021
never cooked up a more
fantastic experience
324
00:21:02,056 --> 00:21:04,624
than the Army engineers
325
00:21:04,658 --> 00:21:06,826
at their laboratory
in Belmar, New Jersey.
326
00:21:06,861 --> 00:21:08,828
It opens up
unlimited possibilities
327
00:21:08,863 --> 00:21:10,663
for interstellar experiment.
328
00:21:10,698 --> 00:21:11,931
American engineers
329
00:21:11,966 --> 00:21:14,534
bounced a beam
of radio waves off the Moon,
330
00:21:14,568 --> 00:21:16,769
and were able
to detect its echo.
331
00:21:23,544 --> 00:21:26,546
They called this experiment
Project Diana.
332
00:21:26,580 --> 00:21:28,214
It was the first
interstellar message
333
00:21:28,249 --> 00:21:30,283
ever sent by our species...
334
00:21:32,753 --> 00:21:34,754
an eerie, tolling bell.
335
00:21:36,423 --> 00:21:40,160
If one allows
the imagination free reign,
336
00:21:40,194 --> 00:21:43,396
many future
possibilities appear.
337
00:21:45,432 --> 00:21:48,201
Spaceships, carrying passengers
338
00:21:48,235 --> 00:21:50,136
at thousands of miles per hour,
339
00:21:50,171 --> 00:21:52,038
can be controlled
340
00:21:52,072 --> 00:21:54,207
and communication established
341
00:21:54,241 --> 00:21:55,909
with their passengers,
342
00:21:55,943 --> 00:21:58,578
for we now know that
the Earth's atmosphere
343
00:21:58,612 --> 00:22:00,447
can be penetrated.
344
00:22:06,120 --> 00:22:08,354
Traveling at
the speed of light,
345
00:22:08,389 --> 00:22:09,689
it takes just over one second
346
00:22:09,723 --> 00:22:11,891
for a radio wave
to reach the lunar surface.
347
00:22:13,461 --> 00:22:17,363
But the expanding wavefront
is much bigger than the Moon.
348
00:22:17,398 --> 00:22:19,899
Most of the wave
passes right by it,
349
00:22:19,934 --> 00:22:22,302
but the central part
gets bounced back.
350
00:22:24,205 --> 00:22:27,173
After a round-trip travel time
of two and a half seconds,
351
00:22:27,208 --> 00:22:28,541
it hits our planet.
352
00:22:29,944 --> 00:22:31,945
Project Diana transmitted
353
00:22:31,979 --> 00:22:33,747
a series of powerful
radio waves--
354
00:22:33,781 --> 00:22:35,181
one every four seconds--
355
00:22:35,216 --> 00:22:37,350
to "ping" the Moon.
356
00:22:39,620 --> 00:22:43,223
The parts that missed the Moon
are traveling still.
357
00:22:45,993 --> 00:22:47,894
It was just the beginning.
358
00:22:47,928 --> 00:22:49,462
After World War II,
359
00:22:49,497 --> 00:22:52,565
television stations cropped up
all over the United States,
360
00:22:52,600 --> 00:22:53,900
and other parts of the world.
361
00:22:55,636 --> 00:22:57,437
The Project Diana message
362
00:22:57,471 --> 00:23:00,407
and the FM radio, television
and radar signals
363
00:23:00,441 --> 00:23:01,875
of the 20th century
364
00:23:01,909 --> 00:23:03,910
all move outward
at the speed of light.
365
00:23:03,944 --> 00:23:08,214
These transmissions make up
a vast sphere of radio waves,
366
00:23:08,249 --> 00:23:11,251
expanding away from the Earth
in all directions.
367
00:23:11,285 --> 00:23:13,286
You could say that our world
368
00:23:13,320 --> 00:23:16,423
is radiating stories.
369
00:23:16,457 --> 00:23:19,592
Our ancestors etched
the story of Gilgamesh
370
00:23:19,627 --> 00:23:21,428
into clay tablets,
371
00:23:21,462 --> 00:23:24,397
sending that epic tale
into the future.
372
00:23:24,432 --> 00:23:27,267
We've encoded our stories
in radio waves
373
00:23:27,301 --> 00:23:29,169
and beamed them into space.
374
00:23:29,203 --> 00:23:31,738
They cover one light-year
of distance--
375
00:23:31,772 --> 00:23:34,107
that's six trillion miles--
376
00:23:34,141 --> 00:23:36,576
for every year of time
since they were sent.
377
00:23:36,610 --> 00:23:39,079
We've been sending
our stories into space
378
00:23:39,113 --> 00:23:40,914
for over 70 years.
379
00:23:40,948 --> 00:23:42,582
The leading edge
of these signals
380
00:23:42,616 --> 00:23:44,284
has already washed over
381
00:23:44,318 --> 00:23:46,586
thousands of planets
of other stars.
382
00:23:46,620 --> 00:23:48,688
If any of these worlds are home
383
00:23:48,723 --> 00:23:51,257
to a civilization
with radio telescopes,
384
00:23:51,292 --> 00:23:54,194
they could already know
that we're here.
385
00:23:57,565 --> 00:23:59,799
What if other worlds
are sending
386
00:23:59,834 --> 00:24:01,835
their stories into space?
387
00:24:03,471 --> 00:24:05,839
Since 1960,
we've been listening
388
00:24:05,873 --> 00:24:07,974
for extraterrestrial
radio signals
389
00:24:08,008 --> 00:24:11,277
without hearing so much
as a tolling bell.
390
00:24:11,312 --> 00:24:13,980
But our search
has been sporadic
391
00:24:14,014 --> 00:24:16,216
and limited to
certain parts of the sky.
392
00:24:21,355 --> 00:24:22,822
For all we know,
393
00:24:22,857 --> 00:24:25,492
we may have just missed
an alien signal,
394
00:24:25,526 --> 00:24:27,060
looking in the wrong place
395
00:24:27,094 --> 00:24:29,229
at the wrong time.
396
00:24:29,263 --> 00:24:31,364
We've only listened to
a miniscule fraction
397
00:24:31,399 --> 00:24:33,066
of the stars in our galaxy.
398
00:24:33,100 --> 00:24:34,734
And there may be
another problem...
399
00:24:34,769 --> 00:24:36,569
we are, to some extent,
400
00:24:36,604 --> 00:24:38,538
prisoners of our own
moment in time
401
00:24:38,572 --> 00:24:40,473
and the limits
of our technology.
402
00:24:40,508 --> 00:24:42,976
Radio and television
broadcasting
403
00:24:43,010 --> 00:24:45,412
may be only
a brief passing phase
404
00:24:45,446 --> 00:24:48,081
in our technological
development.
405
00:24:48,115 --> 00:24:50,817
When we imagine
alien civilizations
406
00:24:50,851 --> 00:24:53,253
broadcasting signals
with radio telescopes,
407
00:24:53,287 --> 00:24:56,489
are we any different
from earlier generations
408
00:24:56,524 --> 00:25:00,026
who imagined riding
cannon shells to the Moon?
409
00:25:01,529 --> 00:25:04,464
Civilizations even slightly
more advanced than ours
410
00:25:04,466 --> 00:25:06,099
may have already moved on
411
00:25:06,101 --> 00:25:08,835
to some other mode
of communication,
412
00:25:08,837 --> 00:25:10,737
one that we have
yet to discover
413
00:25:10,739 --> 00:25:12,739
or even imagine.
414
00:25:12,741 --> 00:25:14,307
Their messages could be
415
00:25:14,309 --> 00:25:16,076
swirling around us,
at this very moment,
416
00:25:16,078 --> 00:25:19,746
but we lack the means
to perceive them,
417
00:25:19,748 --> 00:25:21,514
just as all of our ancestors,
418
00:25:21,516 --> 00:25:23,283
up to a little more
than a century ago,
419
00:25:23,285 --> 00:25:26,486
would have been oblivious to
the most urgent radio signal
420
00:25:26,488 --> 00:25:29,356
from another world.
421
00:25:29,358 --> 00:25:32,525
But there's another,
more troubling possibility--
422
00:25:32,527 --> 00:25:35,295
civilizations,
like other living things,
423
00:25:35,297 --> 00:25:38,031
may only live so long
before perishing
424
00:25:38,065 --> 00:25:40,300
due to natural causes,
or violence,
425
00:25:40,334 --> 00:25:42,635
or self-inflicted wounds.
426
00:25:42,670 --> 00:25:44,971
Whether or not
we ever make contact
427
00:25:45,006 --> 00:25:46,406
with intelligent alien life
428
00:25:46,440 --> 00:25:48,875
may depend on
a critical question.
429
00:25:48,909 --> 00:25:53,013
What is the life expectancy
of a civilization?
430
00:26:16,627 --> 00:26:19,095
By the time of Enheduanna,
431
00:26:19,130 --> 00:26:21,331
the first person
to ever get a writing credit,
432
00:26:21,365 --> 00:26:24,434
civilization was already
more than 1,000 years old.
433
00:26:26,470 --> 00:26:30,774
But today, her glorious city
is a barren wasteland.
434
00:26:30,808 --> 00:26:32,208
What went wrong?
435
00:26:32,243 --> 00:26:34,577
One problem was
the almost ceaseless warfare
436
00:26:34,612 --> 00:26:36,846
between the cities
of Mesopotamia,
437
00:26:36,881 --> 00:26:39,516
which continually destroyed
their achievements.
438
00:26:39,550 --> 00:26:41,684
They glorified military conquest
439
00:26:41,719 --> 00:26:45,121
and ultimately
became its victims.
440
00:26:47,558 --> 00:26:49,592
Another cause of decline
441
00:26:49,627 --> 00:26:51,294
was that their
technical know-how
442
00:26:51,328 --> 00:26:53,763
overran their
understanding of nature.
443
00:26:53,798 --> 00:26:56,466
The ingenious irrigation system
that was the basis
444
00:26:56,500 --> 00:26:58,968
for the great civilizations
of Mesopotamia
445
00:26:59,003 --> 00:27:00,937
had an unintended consequence--
446
00:27:00,971 --> 00:27:04,307
the water channeled into
their farmlands every year
447
00:27:04,341 --> 00:27:07,944
evaporated and left
its salt behind.
448
00:27:07,978 --> 00:27:10,547
Over generations,
the salt accumulated
449
00:27:10,581 --> 00:27:12,382
and began to kill the crops.
450
00:27:12,416 --> 00:27:15,652
And then, about 2,200 BC,
451
00:27:15,686 --> 00:27:17,987
not long after
the time of Enheduanna,
452
00:27:18,022 --> 00:27:19,923
disaster struck...
453
00:27:19,957 --> 00:27:23,059
a drought of truly
epic proportions,
454
00:27:23,094 --> 00:27:24,627
lasting for many decades.
455
00:27:24,662 --> 00:27:26,563
The rains stopped,
crops withered,
456
00:27:26,597 --> 00:27:28,064
and there was famine
and anarchy.
457
00:27:28,099 --> 00:27:29,899
Barbarians invaded.
458
00:27:29,934 --> 00:27:33,570
The streets of many cities
were littered with dead.
459
00:27:33,604 --> 00:27:35,472
There could be only
one explanation.
460
00:27:35,506 --> 00:27:37,474
Enlil, the supreme god,
461
00:27:37,508 --> 00:27:40,076
was angry because
one of his temples
462
00:27:40,111 --> 00:27:41,578
had been destroyed.
463
00:27:41,612 --> 00:27:44,914
The people of Mesopotamia
could not know
464
00:27:44,949 --> 00:27:46,649
that the same drought
was crushing
465
00:27:46,684 --> 00:27:48,618
the dawning civilizations
of Egypt,
466
00:27:48,652 --> 00:27:50,253
Greece, India,
467
00:27:50,287 --> 00:27:51,955
Pakistan and China.
468
00:27:51,989 --> 00:27:53,656
All the gods of the Earth
469
00:27:53,691 --> 00:27:56,593
must have been really angry
about something.
470
00:27:56,627 --> 00:27:58,028
For all their brilliance,
471
00:27:58,062 --> 00:27:59,696
the people of
those civilizations
472
00:27:59,730 --> 00:28:01,931
had no inkling
they were experiencing
473
00:28:01,966 --> 00:28:04,167
abrupt climate change.
474
00:28:08,039 --> 00:28:10,306
3,000 years later, the climate
475
00:28:10,341 --> 00:28:13,276
would change abruptly for
another glorious civilization,
476
00:28:13,310 --> 00:28:15,378
this one in Central America.
477
00:28:15,413 --> 00:28:16,813
At its peak,
478
00:28:16,847 --> 00:28:18,982
the Mayan civilization
perished,
479
00:28:19,016 --> 00:28:21,484
wiped out by a series
of severe droughts
480
00:28:21,519 --> 00:28:22,886
over the course of a century.
481
00:28:22,920 --> 00:28:25,388
We still carry within us
482
00:28:25,423 --> 00:28:28,124
the echoes of these
extinct civilizations
483
00:28:28,159 --> 00:28:30,860
in our languages and our myths.
484
00:28:30,895 --> 00:28:34,798
Today, we have a single
global civilization.
485
00:28:34,832 --> 00:28:36,633
How long will it live?
486
00:28:36,667 --> 00:28:40,203
There are so many ways
for a civilization to die.
487
00:28:40,237 --> 00:28:41,638
Let's start with the ones
488
00:28:41,672 --> 00:28:43,673
that we probably wouldn't
be able to do much about.
489
00:28:45,910 --> 00:28:49,512
That supernova
is 1,000 light-years away.
490
00:28:49,547 --> 00:28:51,681
If it were much closer, say...
491
00:28:51,716 --> 00:28:54,184
less than 30 light-years
from Earth,
492
00:28:54,218 --> 00:28:56,486
its cosmic radiation
would shred
493
00:28:56,520 --> 00:28:58,555
the atmosphere's
protective ozone layer
494
00:28:58,589 --> 00:29:00,757
and destroy our civilization.
495
00:29:00,791 --> 00:29:04,260
Lucky for us, none of the stars
close enough to harm us
496
00:29:04,295 --> 00:29:06,029
are likely to go supernova
497
00:29:06,063 --> 00:29:08,431
any time in the next
few hundred million years.
498
00:29:14,372 --> 00:29:16,172
Every million years or so,
499
00:29:16,207 --> 00:29:19,909
a supervolcano erupts
somewhere on Earth.
500
00:29:19,944 --> 00:29:24,214
The last time it happened
was 74,000 years ago,
501
00:29:24,248 --> 00:29:25,715
on the island of Sumatra,
502
00:29:25,750 --> 00:29:28,618
in what is now Indonesia.
503
00:29:28,653 --> 00:29:30,553
It spewed
hundreds of times more
504
00:29:30,588 --> 00:29:32,522
rock, ash and toxic gas
505
00:29:32,556 --> 00:29:35,725
than any single volcano
in recorded history.
506
00:29:35,760 --> 00:29:39,129
The molten rock that erupted
from Earth's crust
507
00:29:39,163 --> 00:29:41,031
left this caldera,
508
00:29:41,065 --> 00:29:42,766
100 kilometers long,
509
00:29:42,800 --> 00:29:44,935
now filled with a lake.
510
00:29:47,905 --> 00:29:52,709
The Toba volcano sent
more than 600 cubic miles
511
00:29:52,743 --> 00:29:55,745
of pulverized rock
soaring skyward.
512
00:29:55,780 --> 00:29:59,583
The westward wind carried the
volcanic ash over India,
513
00:29:59,617 --> 00:30:01,651
where it fell out
in a smothering blanket
514
00:30:01,686 --> 00:30:04,454
over the subcontinent.
515
00:30:04,488 --> 00:30:07,057
The eruption loaded
the upper atmosphere
516
00:30:07,091 --> 00:30:08,792
with sulfur gases.
517
00:30:08,826 --> 00:30:10,760
The result was a global haze
518
00:30:10,795 --> 00:30:12,662
that blocked most
of the sunlight
519
00:30:12,697 --> 00:30:15,231
from reaching the surface
for at least five years.
520
00:30:15,266 --> 00:30:18,535
It was like one
five-year-long cloudy day.
521
00:30:19,804 --> 00:30:22,639
This so-called
"volcanic winter"
522
00:30:22,673 --> 00:30:26,676
resembled a "nuclear winter,"
but without the radiation.
523
00:30:27,712 --> 00:30:30,146
Temperatures fell everywhere.
524
00:30:30,181 --> 00:30:32,782
Plants and animals froze
even in the tropics,
525
00:30:32,817 --> 00:30:34,684
dying in enormous numbers.
526
00:30:34,719 --> 00:30:36,186
But life is hardy.
527
00:30:36,220 --> 00:30:39,256
Only a few species
were driven to extinction.
528
00:30:39,290 --> 00:30:41,825
One of our ancestors
in central India
529
00:30:41,859 --> 00:30:43,260
sharpened this stone blade
530
00:30:43,294 --> 00:30:45,662
in the years before
the Toba eruption.
531
00:30:45,696 --> 00:30:47,831
And this blade
532
00:30:47,865 --> 00:30:49,432
was one of dozens
that were found
533
00:30:49,467 --> 00:30:52,102
in the soil layer
above the volcanic fallout.
534
00:30:52,136 --> 00:30:54,604
This tells us that
some toolmakers,
535
00:30:54,639 --> 00:30:57,140
even in the area directly
affected by the volcano,
536
00:30:57,174 --> 00:30:59,276
managed to survive
the cataclysm.
537
00:30:59,310 --> 00:31:01,845
But the global human population
538
00:31:01,879 --> 00:31:04,147
must have plummeted
before rebounding.
539
00:31:04,181 --> 00:31:07,150
If an eruption like this
were to happen tomorrow,
540
00:31:07,184 --> 00:31:09,953
our civilization
would be brought to its knees,
541
00:31:09,987 --> 00:31:13,223
although the human species
would survive.
542
00:31:15,493 --> 00:31:17,627
I can imagine that
our technology
543
00:31:17,662 --> 00:31:19,329
of a few hundred years from now
544
00:31:19,363 --> 00:31:20,830
would allow us to siphon off
545
00:31:20,865 --> 00:31:22,866
the energy of
a threatening supervolcano
546
00:31:22,900 --> 00:31:24,701
before it explodes.
547
00:31:24,735 --> 00:31:27,204
We could then use that energy
for our own purposes.
548
00:31:27,238 --> 00:31:30,006
About once every million years,
a small asteroid
549
00:31:30,041 --> 00:31:31,641
collides with the Earth,
550
00:31:31,676 --> 00:31:34,044
causing a similar amount
of devastation.
551
00:31:34,078 --> 00:31:36,079
With our current science
and technology,
552
00:31:36,113 --> 00:31:39,015
we already know how to prevent
an asteroid impact.
553
00:31:39,050 --> 00:31:41,084
We would see it coming
years in advance
554
00:31:41,118 --> 00:31:42,719
and could send
a spacecraft there
555
00:31:42,753 --> 00:31:45,021
to deflect it into
a harmless orbit.
556
00:31:45,056 --> 00:31:47,090
With the technology
of a thousand years from now,
557
00:31:47,124 --> 00:31:49,926
we might even be able
to mitigate the deadly effects
558
00:31:49,961 --> 00:31:52,863
of a nearby supernova
on Earth's atmosphere.
559
00:31:52,897 --> 00:31:55,031
But what happens
560
00:31:55,066 --> 00:31:57,501
when the danger
to a civilization is invisible?
561
00:31:57,535 --> 00:31:59,236
When no one can see it coming?
562
00:32:08,604 --> 00:32:09,904
Beginning with Columbus,
563
00:32:09,939 --> 00:32:12,007
the European invaders
of the Americas
564
00:32:12,041 --> 00:32:15,910
had a secret weapon that even
they knew nothing about.
565
00:32:15,945 --> 00:32:18,847
They were carrying
bacteria and viruses
566
00:32:18,881 --> 00:32:20,982
for deadly diseases,
such as smallpox,
567
00:32:21,017 --> 00:32:24,919
that the original Americans
had never been exposed to.
568
00:32:24,954 --> 00:32:26,921
The Europeans like to believe
569
00:32:26,956 --> 00:32:28,957
that it was their valor
and superior weapons
570
00:32:28,991 --> 00:32:31,826
and culture
that won them the New World.
571
00:32:31,861 --> 00:32:34,095
The real conquistadors were
572
00:32:34,130 --> 00:32:36,364
the armies of the pathogens
that raced on ahead
573
00:32:36,399 --> 00:32:40,201
to infect and kill nine out
of ten of all the Indians
574
00:32:40,236 --> 00:32:43,004
of North, Central
and South America.
575
00:32:44,674 --> 00:32:46,441
The great civilizations
of the New World
576
00:32:46,475 --> 00:32:49,945
crumbled under the onslaught
of invading microbes.
577
00:32:49,979 --> 00:32:51,980
Without his invisible army,
578
00:32:52,014 --> 00:32:54,049
Cortez and those who followed
579
00:32:54,083 --> 00:32:57,852
might never
have stood a chance.
580
00:32:57,887 --> 00:33:01,389
But what about civilizations
that self-destruct?
581
00:33:09,599 --> 00:33:12,200
Our economic systems were
formed when the planet
582
00:33:12,234 --> 00:33:15,070
and its air, rivers,
oceans, lands,
583
00:33:15,104 --> 00:33:18,873
all seemed infinite.
584
00:33:18,908 --> 00:33:21,810
They evolved long before
we first saw the Earth
585
00:33:21,844 --> 00:33:25,513
as the tiny organism
that it actually is.
586
00:33:25,548 --> 00:33:27,182
They're all alike
in one respect...
587
00:33:27,216 --> 00:33:28,850
they're profit-driven,
588
00:33:28,884 --> 00:33:32,621
and therefore,
focused on short-term gain.
589
00:33:59,115 --> 00:34:01,116
The prevailing
economic systems,
590
00:34:01,150 --> 00:34:03,618
no matter what
their ideologies,
591
00:34:03,653 --> 00:34:05,353
have no built-in mechanisms
592
00:34:05,388 --> 00:34:07,389
for protecting our descendants
593
00:34:07,423 --> 00:34:09,424
of even 100 years from now,
594
00:34:09,458 --> 00:34:11,826
let alone, 100,000.
595
00:34:16,832 --> 00:34:18,800
In one respect, we're ahead
596
00:34:18,834 --> 00:34:21,102
of the people
of Ancient Mesopotamia.
597
00:34:21,137 --> 00:34:25,073
Unlike them, we understand
what's happening to our world.
598
00:34:25,107 --> 00:34:27,442
For example,
we're pumping greenhouse gasses
599
00:34:27,476 --> 00:34:30,045
into our atmosphere
at a rate not seen on Earth
600
00:34:30,079 --> 00:34:31,546
for a million years.
601
00:34:31,581 --> 00:34:33,281
And the scientific consensus
602
00:34:33,316 --> 00:34:35,483
that we're destabilizing
our climate.
603
00:34:35,518 --> 00:34:39,421
Yet our civilization seems
to be in the grip of denial;
604
00:34:39,455 --> 00:34:41,957
a kind of paralysis.
605
00:34:41,991 --> 00:34:43,992
There's a disconnect
between what we know
606
00:34:44,026 --> 00:34:46,027
and what we do.
607
00:34:48,931 --> 00:34:52,601
Being able to adapt
our behavior to challenges
608
00:34:52,635 --> 00:34:56,805
is as good a definition
of intelligence as any I know.
609
00:35:01,010 --> 00:35:04,946
If our greater intelligence
is the hallmark of our species,
610
00:35:04,981 --> 00:35:06,448
then we should use it,
611
00:35:06,482 --> 00:35:08,583
as all other beings use their
distinctive advantages--
612
00:35:08,618 --> 00:35:11,019
to help ensure
that their offspring prosper,
613
00:35:11,053 --> 00:35:13,288
and their heredity
is passed on,
614
00:35:13,322 --> 00:35:17,659
and that the fabric of nature
that sustains us is protected.
615
00:35:17,693 --> 00:35:20,495
Human intelligence
is imperfect, surely,
616
00:35:20,530 --> 00:35:22,931
and newly arisen.
617
00:35:22,965 --> 00:35:25,834
The ease with which it can be
sweet-talked, overwhelmed,
618
00:35:25,868 --> 00:35:27,769
or subverted by other
hard-wired tendencies,
619
00:35:27,803 --> 00:35:31,706
sometimes themselves disguised
as the light of reason,
620
00:35:31,741 --> 00:35:33,942
is worrisome.
621
00:35:33,976 --> 00:35:36,211
But if our intelligence
is the only edge,
622
00:35:36,245 --> 00:35:37,846
we must learn to use it better.
623
00:35:37,880 --> 00:35:39,614
To sharpen it.
624
00:35:39,649 --> 00:35:41,950
To understand its limitations
and deficiencies.
625
00:35:41,984 --> 00:35:45,854
To use it as cats use stealth
before pouncing.
626
00:35:45,888 --> 00:35:48,456
As walking sticks
use camouflage.
627
00:35:48,491 --> 00:35:51,660
To make it the tool
of our survival.
628
00:35:51,694 --> 00:35:53,728
If we do this, we can solve
629
00:35:53,763 --> 00:35:56,498
almost any problem
we are likely to confront
630
00:35:56,532 --> 00:35:58,867
in the next 100,000 years.
631
00:36:05,508 --> 00:36:07,642
And now we've arrived
at the place
632
00:36:07,677 --> 00:36:10,145
where our ancient dreams
of immortality
633
00:36:10,179 --> 00:36:13,748
and modern astrophysics
converge.
634
00:36:13,783 --> 00:36:15,851
Giant elliptical galaxies
635
00:36:15,885 --> 00:36:18,386
are something like... Florida,
636
00:36:18,421 --> 00:36:22,123
where the oldest stars
in the universe may be found.
637
00:36:27,864 --> 00:36:29,998
This is a red dwarf star,
638
00:36:30,032 --> 00:36:32,701
smaller and fainter
than our Sun.
639
00:36:32,735 --> 00:36:37,205
Red dwarfs are by far the most
plentiful stars in the cosmos.
640
00:36:37,240 --> 00:36:39,341
Unlike the Sun, which is
halfway through
641
00:36:39,375 --> 00:36:41,343
its 10-billion-year lifetime,
642
00:36:41,377 --> 00:36:44,279
red dwarfs will continue
to provide light and warmth
643
00:36:44,313 --> 00:36:47,215
to their planets
for trillions of years.
644
00:36:47,250 --> 00:36:48,884
That's hundreds of times longer
645
00:36:48,918 --> 00:36:52,020
than the present age
of the universe.
646
00:36:52,054 --> 00:36:53,855
What would
intelligent beings do
647
00:36:53,890 --> 00:36:55,357
if they had an eternity
648
00:36:55,391 --> 00:36:58,693
to develop their understanding
of the universe?
649
00:36:58,728 --> 00:37:00,929
Perhaps they would learn
how to open shortcuts
650
00:37:00,963 --> 00:37:03,098
in the fabric of spacetime,
651
00:37:03,132 --> 00:37:05,033
to travel between galaxies
652
00:37:05,067 --> 00:37:06,868
faster than the speed of light.
653
00:37:06,903 --> 00:37:09,738
Maybe they would create
whole new universes
654
00:37:09,772 --> 00:37:13,241
as artistic
or scientific experiments.
655
00:37:13,276 --> 00:37:16,111
Of course no one,
or at least nobody on Earth,
656
00:37:16,145 --> 00:37:18,914
knows what
the immortals might do.
657
00:37:20,149 --> 00:37:24,219
If one allows
the imagination free reign.
658
00:37:24,253 --> 00:37:25,921
But what about us?
659
00:37:28,958 --> 00:37:31,293
What is our own future?
660
00:37:31,327 --> 00:37:33,328
What would the Cosmic Calendar
661
00:37:33,362 --> 00:37:37,099
of the next 14 billion years
look like?
662
00:37:51,636 --> 00:37:53,470
If the original Cosmic Calendar
663
00:37:53,504 --> 00:37:55,973
includes all of time
from the birth of the universe
664
00:37:56,007 --> 00:37:57,941
until this very moment...
665
00:37:57,976 --> 00:38:00,844
what would
the Cosmic Calendar look like
666
00:38:00,878 --> 00:38:04,648
for the next 14 billion years?
667
00:38:04,682 --> 00:38:07,117
Just as with
the Cosmic Calendar of the past,
668
00:38:07,151 --> 00:38:09,419
every month the future calendar
669
00:38:09,454 --> 00:38:11,621
equals about a billion years;
670
00:38:11,656 --> 00:38:14,558
every day, some 40 million.
671
00:38:15,793 --> 00:38:18,629
Science makes it possible
for us to foretell
672
00:38:18,663 --> 00:38:20,664
certain astronomical events
673
00:38:20,698 --> 00:38:23,667
in the unimaginably
distant future--
674
00:38:23,701 --> 00:38:25,969
the death of the Sun,
for example.
675
00:38:26,004 --> 00:38:28,372
In some five billion years,
676
00:38:28,406 --> 00:38:31,642
our star will have
exhausted its hydrogen--
677
00:38:31,676 --> 00:38:33,710
the nuclear fuel
that powers it--
678
00:38:33,745 --> 00:38:35,879
becoming a red giant.
679
00:38:35,913 --> 00:38:37,948
I know that sounds depressing,
680
00:38:37,982 --> 00:38:40,851
but if we apply our
intelligence, our descendants
681
00:38:40,885 --> 00:38:43,954
of that distant future
will have long departed
682
00:38:43,988 --> 00:38:46,790
from the lost worlds
of the Sun.
683
00:38:46,824 --> 00:38:48,625
Who knows?
684
00:38:48,660 --> 00:38:50,661
Human events entail
too many variables,
685
00:38:50,695 --> 00:38:52,396
too many uncertainties,
686
00:38:52,430 --> 00:38:54,965
to make scientific statements
about our future.
687
00:38:54,999 --> 00:38:57,067
But we can still dream.
688
00:38:57,101 --> 00:38:59,836
The next golden age
of human achievement
689
00:38:59,871 --> 00:39:02,039
begins here and now--
690
00:39:02,073 --> 00:39:06,009
New Year's Day
of the next cosmic year.
691
00:39:06,044 --> 00:39:08,145
In the first tenth of a second,
692
00:39:08,179 --> 00:39:11,415
we take the vision
of the pale blue dot to heart,
693
00:39:11,449 --> 00:39:15,018
and learn how to share this
tiny world with each other.
694
00:39:15,053 --> 00:39:17,020
The last
internal combustion engine
695
00:39:17,055 --> 00:39:18,855
is placed in a museum,
696
00:39:18,890 --> 00:39:21,658
as the effects of climate change
reverse and diminish.
697
00:39:21,693 --> 00:39:25,529
A fifth of a second
into this future
698
00:39:25,563 --> 00:39:28,498
people will stop dying
from the effects of poverty.
699
00:39:28,533 --> 00:39:31,568
The planet is now
a completely self-sustaining,
700
00:39:31,603 --> 00:39:34,004
intercommunicating organism.
701
00:39:34,038 --> 00:39:36,073
A half-second from now,
702
00:39:36,107 --> 00:39:37,708
the polar ice caps are restored
703
00:39:37,742 --> 00:39:40,077
to the way they were
in the 19th century,
704
00:39:40,111 --> 00:39:43,046
and the forecast
is mild and pleasant
705
00:39:43,081 --> 00:39:45,349
for the next cosmic
minute and a half--
706
00:39:45,383 --> 00:39:48,418
40,000 years.
707
00:39:48,453 --> 00:39:50,587
By the time
we are ready to settle
708
00:39:50,622 --> 00:39:53,290
even the nearest
other planetary systems,
709
00:39:53,324 --> 00:39:56,126
we will have changed.
710
00:39:56,160 --> 00:39:58,896
The simple passage
of so many generations
711
00:39:58,930 --> 00:40:00,931
will have changed us.
712
00:40:00,965 --> 00:40:04,368
Necessity will have changed us.
713
00:40:04,402 --> 00:40:07,404
We are an adaptable species.
714
00:40:09,140 --> 00:40:11,541
It will not be we
who reach Alpha Centauri
715
00:40:11,576 --> 00:40:13,644
and the other
nearby star systems
716
00:40:13,678 --> 00:40:15,746
on our interstellar arks.
717
00:40:15,780 --> 00:40:18,382
It will be a species
very like us,
718
00:40:18,416 --> 00:40:22,119
but with more of our strengths
and fewer of our weaknesses;
719
00:40:22,153 --> 00:40:24,221
more confident, far-seeing,
720
00:40:24,255 --> 00:40:26,957
capable and wise.
721
00:40:26,991 --> 00:40:28,725
For all our failings,
722
00:40:28,760 --> 00:40:31,228
despite our flaws
and limitations,
723
00:40:31,262 --> 00:40:34,965
we humans are capable
of greatness.
724
00:40:34,999 --> 00:40:38,235
What new wonders,
undreamt of in our time,
725
00:40:38,269 --> 00:40:41,772
will we have accomplished
in another generation...
726
00:40:41,806 --> 00:40:43,807
and another?
727
00:40:45,043 --> 00:40:47,177
How far will
our nomadic species
728
00:40:47,212 --> 00:40:50,747
have wandered
by the end of the next century,
729
00:40:50,782 --> 00:40:53,617
and the next millennium?
730
00:40:53,651 --> 00:40:56,086
Our remote descendants,
731
00:40:56,120 --> 00:40:57,988
safely arrayed on many worlds
732
00:40:58,022 --> 00:41:00,624
throughout the solar system
and beyond,
733
00:41:00,658 --> 00:41:03,994
will be unified
by their common heritage,
734
00:41:04,028 --> 00:41:07,464
by their regard
for their home planet,
735
00:41:07,498 --> 00:41:11,168
and by their knowledge that,
whatever other life may be,
736
00:41:11,202 --> 00:41:13,971
the only humans
in all the universe
737
00:41:14,005 --> 00:41:17,140
came from Earth.
738
00:41:17,175 --> 00:41:19,142
They will gaze up
and strain to find
739
00:41:19,177 --> 00:41:21,945
the blue dot in their skies.
740
00:41:21,980 --> 00:41:24,214
They will marvel
at how vulnerable
741
00:41:24,249 --> 00:41:27,885
the repository of all
our potential once was,
742
00:41:27,919 --> 00:41:30,787
how perilous our infancy,
743
00:41:30,822 --> 00:41:34,892
how humble our beginnings,
744
00:41:34,926 --> 00:41:37,828
how many rivers
we had to cross...
745
00:41:40,765 --> 00:41:43,200
before we found our way.