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♪

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narrator: Earth --
a planet defined by life.

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Stricker: The amazing thing
about life here on earth

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is no matter where you look,
you'll find it.

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 Narrator: But is earth unique?

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Thaller:
 The big question of our day is,

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 does life exist somewhere else
 beside the earth?

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Are we that special,
or is life everywhere?

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Narrator:
 The ingredients for life

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are spread throughout
the universe.

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But then we started looking
into space and saying,

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"wait a second.
That chemistry is everywhere."

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narrator:
Is life inevitable?

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I think that there have to be
 planets out there

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 that are capable
 of hosting life.

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Narrator: What does life need
to get started,

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 and once started,
 can life spread?

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It's possible that life
started on mars

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and was transferred to earth
inside of a meteorite.

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Narrator:
 Life has conquered our planet,

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but can life conquer
the universe?

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the universe
is a very big place.

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There are trillions of galaxies,

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each one home
to millions of stars

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and an unimaginable number
 of planets.

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So where is everybody?

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One of the most basic
philosophical questions is,

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are we alone?

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Are we the only ones
 looking out and thinking,

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"what is all this?"

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is it all just for us, or do
 we get to share it with anyone?

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I mean, that's about
 as fundamental a question

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 as you get.

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 Narrator: What are the odds of
life existing somewhere else?

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 We just don't have a good
insight

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to how probable life
is anywhere in the universe.

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Life could possibly
be forming everywhere.

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We don't quite know.

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 There's a lot about life
 that we don't understand.

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All we know is that
it happened at least once.

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But beyond this
one little planet,

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we don't know whether or not
it happened anywhere else.

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♪

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 narrator: The universe is
an unfriendly place.

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 Planets with lava oceans
circle too close to their stars.

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Pulsars blaze with
deadly gamma rays and x-rays.

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Black holes consume
everything in their path.

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Temperatures plummet close
 to absolute zero.

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♪

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 it may seem impossible for life

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to survive in such
hostile environments,

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but here on earth,
life exists against the odds

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in some very strange places.

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Life has actually permeated
 every part of our planet.

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 There are places
where you're like,

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"how did you even get there?"

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narrator: At first glance,
 a beautiful lake

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might seem like
a good place for life,

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but california's salton sea
is no paradise.

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The toxic salt waters
are killer...

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...Surrounded by scorched desert

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 and volcanic geothermal fields.

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It's a deadly environment.

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 One of the last places on earth
 you'd expect to find life

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 would be in boiling mud vents.

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You can start to hear
these vents because there's gas,

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and there's water and mud slurry
 that's coming out, right here.

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So these are
active mud volcanoes.

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 It's really hot.

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It's, like...
164 degrees fahrenheit.

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Narrator: But life is resilient,
finding a home even here,

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inside volcanic vents
 in the california desert.

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We're in the middle
of a really hot desert,

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 and as the mud comes up,
it's coming up hot,

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and it's kind of acid,

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and yet there can be microbes
in environments like this,

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happily thriving away.

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 This is an environment that is
actually conducive to life,

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even though we think
 it might not be.

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Narrator: Almost every inch
of the earth's surface

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 is teeming
with microscopic life-forms.

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The thing about life on earth

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is that it exists in so many
different environments

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 under such harsh,
extreme conditions.

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It's like it hangs on,
 no matter what you throw at it.

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 Very dry, high pressure,
very hot,

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even in high radiation
environments,

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 which would kill
a human within seconds.

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Narrator: Life even survives

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being bombed with asteroids
and meteorites.

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We have a wonderful
 indirect example

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 of just how tenacious life is,
and that's the fact

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 that it survived
the late heavy bombardment.

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Narrator:
The late heavy bombardment

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was a violent assault
on young earth,

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where life had just gotten
 a foothold.

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Experts think
around 4 billion years ago,

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 asteroids comets
 and space debris

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 rained down
on the inner solar system.

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This rocky barrage
would've melted parts

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of the earth's crust
and boiled away oceans.

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It was a violent time
 called the hadean period.

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 The hadean named, after hades,
named after the underworld,

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 after hell.

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It was a brutally unpleasant
place to be.

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 It was spewing its own innards
out into the surface

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in this intense cycle
 of hot volcanism.

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Narrator: If life on earth

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overcame these
hellish conditions,

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 then perhaps life
can survive anywhere.

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 Straugh: I think
if it can happen on earth,

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I think it can happen
 on other planets.

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 I think life finds a way,

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and I think we need
to go looking for it.

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Narrator: The question is,
what exactly are we looking for?

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Plait: What is life?

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You know, that seems
like a simple question,

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but it's not
that easy to answer.

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Life is incredibly hard
 to define, right?

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 It's sort of like, you know it
 when you see it,

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but how do you
write down the rules?

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Stricker: Every time we think
 we have a grasp,

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there's this new form
 that comes about

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 and completely questions
that entire definition.

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 There's a joke in astrobiology
that if you ask

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200 scientists
 for a definition of life,

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 you'll get
200 different answers.

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Narrator: Life can be
 as intricate as us humans

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or as simple as single-celled
 organisms, like bacteria,

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 but there are some things
all life-forms do.

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Plait:In broad terms,
life consumes things.

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It breathes. It eats.
It excretes.

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 It grows. It reproduces.
It's complex.

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 Narrator: Life has transformed
 the earth in all sorts of ways,

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 but life is
still just an accident.

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Life, as I see it,
is just a chemical reaction,

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but it's the most important
and special chemical reaction

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in the universe.

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 Narrator: If life is just
a product of chemistry,

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then what are the odds of it

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 starting anywhere
 in the universe?

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 One thing we know
about chemistry

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is that
given the right conditions,

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the same chemical reaction
will reliably occur.

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Narrator:
It's like a game of chance.

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 For life to win, the conditions
need to be just right,

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but to figure out the odds,
we need to understand

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 what those conditions are
 and how common they are.

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 Oluseyi: So it comes down
to a numbers game.

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 It's about statistics and
 probabilities and likelihoods.

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Narrator:
It's like having to roll a 6

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for each condition for life.

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 But how many 6s would you need?

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How many precise conditions
 does life require to get going?

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 You might have 100 dice,
roll them all, get all 6s.

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Only then do you get life.

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Narrator:
You could need hundreds

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 or hundreds of thousands
of dice.

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We just don't know.

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 We honestly have no clue

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how common or rare life is
in the universe.

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Plait: We don't know how life
 originated here on earth,

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where we kind of understand
the conditions.

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There are a lot of different
ways life could've started.

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Is life rare? Is life common?
 We don't where it lands.

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Narrator:
Putting odds on life existing

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is a waste of time
 until we understand it better,

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and maybe our answers
 don't lie here on earth.

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One way to crack this problem

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 is to go looking for life
 elsewhere.

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If we can find
other examples of life,

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we can immediately begin
to put a quantitative answer

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to how probable it is
for life to happen anywhere.

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Narrator: And the best place
 to look for life

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 might be in our own backyard...

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...Mars.

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If life can start here,

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then maybe life
could conquer the universe.

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[ explosions ]

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♪

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narrator: For life to conquer
the universe,

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first, it has to get going.

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 When we look at life on earth,

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 it's possible that it all
has a common ancestor.

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 Life started at one spot,
branched out, and became

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all the different kinds
of life that we see.

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Narrator:
But how did it start?

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The first question to answer is,
what is life made of?

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Top of the list are the most
 basic building blocks --

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chemical elements.

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 Here's what I know about
the universe --

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the laws of physics
appear to be same everywhere.

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 The chemical composition,

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 the elements are the same
 everywhere.

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And the cosmos creates
these elements,

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not from the big bang
but from stars.

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Narrator: Over the course
 of a star's life,

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it creates elements.

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And when a star dies,

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00:11:07,034 --> 00:11:11,803
 these elements are blasted out
into space in a supernova,

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00:11:11,805 --> 00:11:16,741
 spreading the ingredients
for life out into the cosmos.

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00:11:16,743 --> 00:11:19,844
We, the earth, our solar system,

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00:11:19,846 --> 00:11:21,746
all the ingredients
that make us,

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us were forged in nuclear fires.

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00:11:26,286 --> 00:11:30,955
So the death of stars
leads to the birth of life.

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00:11:33,694 --> 00:11:36,194
 Narrator: Those key ingredients
include oxygen,

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00:11:36,196 --> 00:11:39,330
 nitrogen, sulfur,
and phosphorus,

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00:11:39,332 --> 00:11:44,202
but the element most central
to life as we know it is carbon.

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00:11:45,739 --> 00:11:49,841
 All life as we know it on earth
is based on carbon.

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00:11:49,843 --> 00:11:52,377
Carbon forms the structure,

211
00:11:52,379 --> 00:11:55,747
 the architecture
 of our living molecules.

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00:11:58,085 --> 00:12:00,819
Narrator: Carbon is
an incredibly versatile

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00:12:00,821 --> 00:12:03,855
building material.

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00:12:03,857 --> 00:12:07,826
 It can bond with other elements
to form long-chain molecules,

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00:12:07,828 --> 00:12:11,262
 each with different properties.

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00:12:11,264 --> 00:12:14,833
As an element, it seems to be
capable of producing

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00:12:14,835 --> 00:12:19,337
a vast and complex chemistry,

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00:12:19,339 --> 00:12:24,943
and that complex chemistry
 is what we find in life.

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Narrator:
We call this organic chemistry.

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00:12:27,647 --> 00:12:31,116
♪

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00:12:31,118 --> 00:12:33,918
 but getting from
basic organic molecules

222
00:12:33,920 --> 00:12:37,021
to complex life-forms
is a big leap.

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00:12:37,023 --> 00:12:40,792
We don't really have
the slightest idea,

224
00:12:40,794 --> 00:12:45,597
to be honest, about how life
on earth got started.

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00:12:45,599 --> 00:12:49,300
Scharf: A really big question
is, how do you go from a mix

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00:12:49,302 --> 00:12:54,873
of relatively simple organic
molecules to a living system?

227
00:12:54,875 --> 00:12:57,742
 Narrator: We know it all starts
with basic elements created

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00:12:57,744 --> 00:12:59,377
 in massive quantities...

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[ explosion ]

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00:13:00,781 --> 00:13:03,515
 ...By the death of stars.

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00:13:03,517 --> 00:13:07,018
But how do you start connecting
those lego bricks together

232
00:13:07,020 --> 00:13:08,987
 to build that first cell?

233
00:13:08,989 --> 00:13:12,557
The short answer is,
 "we don't know,"

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00:13:12,559 --> 00:13:16,628
but we have some ideas
of potential steps.

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00:13:16,630 --> 00:13:18,997
Narrator:
Chains of organic molecules

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00:13:18,999 --> 00:13:20,732
become more and more complex.

237
00:13:20,734 --> 00:13:23,468
Amino acids form proteins.

238
00:13:23,470 --> 00:13:29,207
 Fatty acids form phospholipids,
which makes cell membranes.

239
00:13:29,209 --> 00:13:31,876
Nucleic acids form dna,

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00:13:31,878 --> 00:13:35,079
 the molecule that stores
genetic information.

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00:13:35,081 --> 00:13:39,684
 Eventually,
a simple cell emerges.

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00:13:39,686 --> 00:13:42,353
So all of the bits you need
 to plug together

243
00:13:42,355 --> 00:13:44,489
to build a cell from scratch

244
00:13:44,491 --> 00:13:48,426
 seems to exist in outer space.

245
00:13:48,428 --> 00:13:50,862
We found organic compounds
 everywhere.

246
00:13:50,864 --> 00:13:53,031
They're all over the place --

247
00:13:53,033 --> 00:13:56,935
planets, comets, gas clouds.

248
00:13:58,505 --> 00:14:01,406
The very basic
ingredients of life

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00:14:01,408 --> 00:14:05,410
available elsewhere
in our solar system,

250
00:14:05,412 --> 00:14:08,079
so there could be life
 everywhere.

251
00:14:08,081 --> 00:14:11,282
♪

252
00:14:11,284 --> 00:14:12,951
narrator: In 2018,

253
00:14:12,953 --> 00:14:16,621
 nasa announces it's found
 organic molecules

254
00:14:16,623 --> 00:14:18,723
on another planet,

255
00:14:18,725 --> 00:14:23,962
 a planet we've always suspected
of harboring alien life --

256
00:14:23,964 --> 00:14:26,364
...Mars.

257
00:14:26,366 --> 00:14:28,733
So whenever nasa has a
press conference, and they say,

258
00:14:28,735 --> 00:14:31,703
 "hey, I have some results
 to report on about mars,"

259
00:14:31,705 --> 00:14:33,404
everyone goes nuts.

260
00:14:33,406 --> 00:14:36,040
Dartnell:
The internet goes mad.

261
00:14:36,042 --> 00:14:38,576
Maybe we've got photograph
 evidence of the green men

262
00:14:38,578 --> 00:14:40,712
in a ufo.

263
00:14:40,714 --> 00:14:42,313
Lanza:
This time, it's the martians.

264
00:14:42,315 --> 00:14:45,383
 They're going to tell us
they found a martian.

265
00:14:45,385 --> 00:14:47,552
 The world listens
 'cause everyone wants to know.

266
00:14:47,554 --> 00:14:49,254
Everyone asks the question,

267
00:14:49,256 --> 00:14:50,989
"have we found evidence
of life?"

268
00:14:53,293 --> 00:14:54,726
narrator: For 6 years,

269
00:14:54,728 --> 00:14:57,562
the mars curiosity
 rover has been exploring

270
00:14:57,564 --> 00:14:59,664
a region called gale crater,

271
00:14:59,666 --> 00:15:02,567
hunting for signs of
ancient life.

272
00:15:04,905 --> 00:15:08,239
 A bit like
 fossil-hunting on earth.

273
00:15:08,241 --> 00:15:10,541
 Gale crater is not unlike
places on earth

274
00:15:10,543 --> 00:15:13,411
that can preserve fossils,
so a really good example of this

275
00:15:13,413 --> 00:15:17,215
would be the petrified forest
 in arizona.

276
00:15:17,217 --> 00:15:21,653
This looks like a piece of wood,
 but in fact, it is stone.

277
00:15:21,655 --> 00:15:24,956
 It is all stone,
 but it used to be a tree.

278
00:15:24,958 --> 00:15:29,460
 This fossil lived
200 million years ago.

279
00:15:29,462 --> 00:15:31,329
Narrator:
 This patch of desert in arizona

280
00:15:31,331 --> 00:15:33,197
 once looked
completely different.

281
00:15:35,368 --> 00:15:37,702
Lanza: This landscape looks
very dry right now,

282
00:15:37,704 --> 00:15:39,070
but 200 million years ago,

283
00:15:39,072 --> 00:15:44,008
it was wet swampland
with trees and flowing water.

284
00:15:45,612 --> 00:15:47,211
Narrator:
Like the petrified forest,

285
00:15:47,213 --> 00:15:51,082
mars has also changed over time.

286
00:15:51,084 --> 00:15:55,853
 Gale crater was once a lake bed
 filled with fresh water.

287
00:15:55,855 --> 00:15:59,624
And it was just so exciting
because we knew then

288
00:15:59,626 --> 00:16:03,194
that we had landed
 right on top of an environment

289
00:16:03,196 --> 00:16:05,496
that once had tons
 of flowing water

290
00:16:05,498 --> 00:16:08,232
 and could very well have
preserved organic materials,

291
00:16:08,234 --> 00:16:11,235
even though it looks very barren
and desolate to our eyes.

292
00:16:13,707 --> 00:16:15,206
Narrator: In 2018,

293
00:16:15,208 --> 00:16:18,409
curiosity drills into
 this ancient martian lake

294
00:16:18,411 --> 00:16:21,245
and discovers organic molecules.

295
00:16:24,484 --> 00:16:27,652
 Finding organics on mars
is so exciting

296
00:16:27,654 --> 00:16:29,454
just because, I mean, wow.

297
00:16:29,456 --> 00:16:31,622
That is -- those are
the building blocks of life,

298
00:16:31,624 --> 00:16:34,025
not just the elements,
but actual molecules.

299
00:16:34,027 --> 00:16:36,661
 There was a wave of excitement

300
00:16:36,663 --> 00:16:38,830
after the announcement
 of organics

301
00:16:38,832 --> 00:16:41,332
found on mars
and complex organics.

302
00:16:41,334 --> 00:16:43,968
It's not totally indicative
that life is there,

303
00:16:43,970 --> 00:16:46,504
but it's a really good
telltale sign

304
00:16:46,506 --> 00:16:51,542
 that there may be
possibly life-forms on mars.

305
00:16:51,544 --> 00:16:54,612
Narrator: The results aren't
proof of martians,

306
00:16:54,614 --> 00:16:58,816
 but the ancient lake bed
 is evidence that the red planet

307
00:16:58,818 --> 00:17:02,854
once had something else
crucial for life --

308
00:17:02,856 --> 00:17:04,188
liquid water.

309
00:17:04,190 --> 00:17:07,558
♪

310
00:17:07,560 --> 00:17:09,627
it's one thing if you have
all these ingredients

311
00:17:09,629 --> 00:17:11,095
lying around for life.

312
00:17:11,097 --> 00:17:12,697
 You could have, you know,
carbon over here and hydrogen

313
00:17:12,699 --> 00:17:15,033
 over here,
maybe methane or whatever.

314
00:17:15,035 --> 00:17:16,534
 You have to mix them together,

315
00:17:16,536 --> 00:17:21,139
 so you need something for them
to be in, a medium of some sort.

316
00:17:21,141 --> 00:17:22,874
Narrator: Life needs a liquid

317
00:17:22,876 --> 00:17:26,844
to mix essential chemicals
together.

318
00:17:26,846 --> 00:17:28,212
 We're used to thinking of earth

319
00:17:28,214 --> 00:17:33,217
as the only water world
in our solar system,

320
00:17:33,219 --> 00:17:35,920
but new evidence says
otherwise...

321
00:17:38,625 --> 00:17:42,126
 ...As extraterrestrial visitors

322
00:17:42,128 --> 00:17:46,531
carrying liquid water
 from outer space reveal.

323
00:17:54,841 --> 00:17:59,277
[ explosions ]

324
00:17:59,279 --> 00:18:00,678
♪

325
00:18:00,680 --> 00:18:02,480
narrator: It's no coincidence

326
00:18:02,482 --> 00:18:05,416
our blue planet is
a water world.

327
00:18:05,418 --> 00:18:09,587
There are more than
366 million trillion gallons

328
00:18:09,589 --> 00:18:12,590
of water on earth.

329
00:18:12,592 --> 00:18:16,394
 It even makes up
60% of our bodies.

330
00:18:16,396 --> 00:18:18,596
I think life on earth
 could be easily described

331
00:18:18,598 --> 00:18:20,898
as water chemistry.

332
00:18:20,900 --> 00:18:24,569
That is the essential feature
 of life on earth.

333
00:18:24,571 --> 00:18:27,038
Narrator:
Some is locked up in ice caps

334
00:18:27,040 --> 00:18:30,007
or as vapor in the air,

335
00:18:30,009 --> 00:18:34,979
but 96% of liquid water
 is in our oceans.

336
00:18:34,981 --> 00:18:37,248
 Well, earth is really special.

337
00:18:37,250 --> 00:18:39,951
 There's no other place like it
 that we've found.

338
00:18:39,953 --> 00:18:43,654
It's a pretty substantial planet
 with liquid water

339
00:18:43,656 --> 00:18:45,756
covering 70% of the surface.

340
00:18:45,758 --> 00:18:48,426
 All life on the earth requires
bodies of water

341
00:18:48,428 --> 00:18:49,660
in order to survive.

342
00:18:49,662 --> 00:18:51,295
No water, no life.

343
00:18:52,765 --> 00:18:56,834
Narrator: Water is what chemists
call a solvent,

344
00:18:56,836 --> 00:19:00,505
 and it's the best solvent
 we know of.

345
00:19:00,507 --> 00:19:04,108
 It can dissolve more substances
than any other liquid,

346
00:19:04,110 --> 00:19:07,645
allowing molecules
to mix and interact.

347
00:19:07,647 --> 00:19:10,948
Wherever water goes,
it transports

348
00:19:10,950 --> 00:19:15,052
valuable chemicals, minerals,
and nutrients.

349
00:19:15,054 --> 00:19:16,521
Oluseyi:
If there was no liquid,

350
00:19:16,523 --> 00:19:18,489
things would just sit around
 separately.

351
00:19:18,491 --> 00:19:20,825
You need this constant
interaction,

352
00:19:20,827 --> 00:19:23,294
and you need
 a different chemical mix,

353
00:19:23,296 --> 00:19:25,530
and water does all of that.

354
00:19:27,534 --> 00:19:31,202
And so a lot of our searches
for lifelike planets,

355
00:19:31,204 --> 00:19:34,605
or earthlike planets,
 outside our solar system

356
00:19:34,607 --> 00:19:38,109
 are based on this sort of
primary assumption

357
00:19:38,111 --> 00:19:40,011
that we need liquid water.

358
00:19:42,248 --> 00:19:44,849
Narrator: We've long thought
earth has liquid water

359
00:19:44,851 --> 00:19:49,620
 because of its unique position
in the solar system.

360
00:19:49,622 --> 00:19:52,990
It's right in this zone that
we call the habitable zone

361
00:19:52,992 --> 00:19:56,561
where the sunlight
 can support liquid water

362
00:19:56,563 --> 00:19:58,262
on the surface of the planet.

363
00:19:58,264 --> 00:20:01,666
♪

364
00:20:01,668 --> 00:20:04,101
 narrator: But we have now
discovered that liquid water

365
00:20:04,103 --> 00:20:07,438
might exist in places
we never expected.

366
00:20:10,043 --> 00:20:14,779
In 1998, a meteorite crash-lands
in texas.

367
00:20:16,149 --> 00:20:19,350
[ explosion ]

368
00:20:19,352 --> 00:20:22,286
 today, scientists
at arizona state university

369
00:20:22,288 --> 00:20:26,023
 are still studying its secrets.

370
00:20:26,025 --> 00:20:27,792
We had no idea
that it would contain

371
00:20:27,794 --> 00:20:31,095
this really,
really spectacular finding.

372
00:20:31,097 --> 00:20:35,066
Narrator: It contains
a mysterious purple mineral.

373
00:20:35,068 --> 00:20:39,103
The exotic color comes from
exposure to cosmic radiation,

374
00:20:39,105 --> 00:20:42,873
but the compound itself
 is very ordinary.

375
00:20:42,875 --> 00:20:44,842
 It's actually sodium chloride,

376
00:20:44,844 --> 00:20:48,312
which is essentially
the same mineral as table salt,

377
00:20:48,314 --> 00:20:51,349
but what's really cool
is that it actually contains

378
00:20:51,351 --> 00:20:54,118
little globules of liquid water,

379
00:20:54,120 --> 00:20:57,588
and that liquid water
was trapped in these crystals

380
00:20:57,590 --> 00:21:00,992
 4 1/2 billion years ago.

381
00:21:00,994 --> 00:21:04,095
Narrator: In 2018, scientists
reexamined the crystals

382
00:21:04,097 --> 00:21:08,366
 and discovered the liquid water
wasn't traveling alone.

383
00:21:08,368 --> 00:21:11,802
 We've now actually found
organic compounds in association

384
00:21:11,804 --> 00:21:15,373
with this liquid water
in these salt crystals,

385
00:21:15,375 --> 00:21:17,842
and that's something
 that's really new

386
00:21:17,844 --> 00:21:20,077
and really spectacular.

387
00:21:22,582 --> 00:21:24,348
Thaller:
 We actually found amino acids,

388
00:21:24,350 --> 00:21:27,752
the building blocks of all
 of our proteins, even our dna,

389
00:21:27,754 --> 00:21:29,387
and we found liquid water,

390
00:21:29,389 --> 00:21:32,523
 the very building blocks
of life, inside a meteorite.

391
00:21:34,761 --> 00:21:36,861
Narrator: So could life exist

392
00:21:36,863 --> 00:21:38,963
somewhere else
in our solar system?

393
00:21:38,965 --> 00:21:42,767
♪

394
00:21:42,769 --> 00:21:47,071
 a nasa mission to saturn
turned up some shocking results.

395
00:21:47,073 --> 00:21:52,176
The cassini space probe flew
beneath saturn's moon enceladus.

396
00:21:52,178 --> 00:21:54,779
Dartnell:
 Enceladus, no one cared about.

397
00:21:54,781 --> 00:22:01,185
 It was a tiny, little snowball
 of a world.

398
00:22:01,187 --> 00:22:04,221
Narrator: But enceladus
surprised everyone.

399
00:22:06,793 --> 00:22:11,028
 Geysers of liquid water,
dozens of them,

400
00:22:11,030 --> 00:22:14,165
blast out of trenches
 along the moon's surface,

401
00:22:14,167 --> 00:22:17,535
 coming from
 a vast subsurface ocean.

402
00:22:21,507 --> 00:22:24,508
Oceans on earth
 are full of life.

403
00:22:27,747 --> 00:22:30,781
Could the same be true
of enceladus?

404
00:22:30,783 --> 00:22:33,284
Mckay:
I'm a big fan of enceladus.

405
00:22:33,286 --> 00:22:37,054
I think it's by far and away
the best place to go

406
00:22:37,056 --> 00:22:39,190
 to search for evidence of life.

407
00:22:39,192 --> 00:22:40,658
Narrator: In 2018,

408
00:22:40,660 --> 00:22:43,694
researchers analyzing
 the cassini data

409
00:22:43,696 --> 00:22:46,330
discovered that the plumes
of enceladus

410
00:22:46,332 --> 00:22:49,367
contain
complex organic molecules.

411
00:22:49,369 --> 00:22:52,903
Just simple molecules,
we find those, like methane,

412
00:22:52,905 --> 00:22:55,306
but the cassini results
are showing that there are

413
00:22:55,308 --> 00:22:59,944
these more complex, larger
organic molecules as well.

414
00:22:59,946 --> 00:23:03,013
Narrator: This is the first ever
detection of complex organics

415
00:23:03,015 --> 00:23:05,950
on an extraterrestrial
water world.

416
00:23:05,952 --> 00:23:09,487
 All of a sudden,
 here's water jetting out,

417
00:23:09,489 --> 00:23:13,724
 carrying organic material, all
the ingredients needed for life.

418
00:23:13,726 --> 00:23:17,728
It was, like, too good
 to be true.

419
00:23:17,730 --> 00:23:20,164
Narrator: But enceladus isn't
the only small world

420
00:23:20,166 --> 00:23:22,133
with a subsurface ocean.

421
00:23:22,135 --> 00:23:26,804
Other moons and dwarf planets
have liquid water, too.

422
00:23:26,806 --> 00:23:29,106
We think the most important
thing for life to form

423
00:23:29,108 --> 00:23:30,708
is the presence of liquid water,

424
00:23:30,710 --> 00:23:33,177
and our solar system
seems to be full of it.

425
00:23:35,548 --> 00:23:38,315
Sutter:
The discovery of liquid water

426
00:23:38,317 --> 00:23:40,050
 in the outer solar system

427
00:23:40,052 --> 00:23:46,624
changes the rules of how life
might originate in the universe.

428
00:23:46,626 --> 00:23:50,227
♪

429
00:23:50,229 --> 00:23:51,729
 narrator: Across the universe,

430
00:23:51,731 --> 00:23:56,567
alien life could be hiding
underneath the surface.

431
00:23:56,569 --> 00:24:00,271
 Internal water oceans are
far more common

432
00:24:00,273 --> 00:24:03,607
than surface water oceans,

433
00:24:03,609 --> 00:24:07,111
so if there is a lot of life
out there in the universe,

434
00:24:07,113 --> 00:24:11,382
 chances are it's in an internal
 ocean under miles of ice.

435
00:24:13,486 --> 00:24:15,186
Narrator:
 Who knows what might be lurking

436
00:24:15,188 --> 00:24:18,456
inside icy exoworlds?

437
00:24:18,458 --> 00:24:22,059
There may be jellyfish
and octopuses all over the place

438
00:24:22,061 --> 00:24:25,262
in exomoons and exoplanets
under ice

439
00:24:25,264 --> 00:24:28,899
that have civilizations
 that we just don't know about.

440
00:24:28,901 --> 00:24:31,001
Narrator:
Finding liquid water oceans

441
00:24:31,003 --> 00:24:33,704
could open up a world
 of possibilities.

442
00:24:35,942 --> 00:24:37,775
If you're not excited about

443
00:24:37,777 --> 00:24:41,011
intelligent extraterrestrial
octopus civilians,

444
00:24:41,013 --> 00:24:42,746
 I don't know what to say.

445
00:24:44,984 --> 00:24:47,852
Narrator: The chances of finding
 life in our solar system

446
00:24:47,854 --> 00:24:49,920
just got a heck of a lot better.

447
00:24:53,259 --> 00:24:57,328
Building blocks
and liquid water are common,

448
00:24:57,330 --> 00:25:00,164
but you need more than
 just these two conditions

449
00:25:00,166 --> 00:25:02,099
for life to take hold.

450
00:25:02,101 --> 00:25:04,768
Life needs a spark.

451
00:25:04,770 --> 00:25:06,804
Life appears to need
some form of energy

452
00:25:06,806 --> 00:25:08,873
to actually get
the molecules interacting.

453
00:25:08,875 --> 00:25:10,975
 One thing that may have helped
 kick-start life on earth

454
00:25:10,977 --> 00:25:13,544
 is ultraviolet radiation
from the sun.

455
00:25:13,546 --> 00:25:17,081
Narrator: Ultraviolet light
 is emitted by all stars.

456
00:25:17,083 --> 00:25:21,385
There are billions of stars
in our galaxy.

457
00:25:21,387 --> 00:25:24,922
Can life get started
 around any star,

458
00:25:24,924 --> 00:25:29,126
or is our sun unique?

459
00:25:35,434 --> 00:25:39,870
[ explosion ]

460
00:25:39,872 --> 00:25:43,607
narrator: Earth is
a solar-powered planet.

461
00:25:43,609 --> 00:25:47,378
At the bottom of the food chain,
 plants use photosynthesis

462
00:25:47,380 --> 00:25:50,881
to convert sunlight
into chemical energy --

463
00:25:50,883 --> 00:25:53,083
 food for the rest of us.

464
00:25:53,085 --> 00:25:56,754
Dartnell: I like eating
 both grass, essentially wheat,

465
00:25:56,756 --> 00:25:59,390
 and I also fancy
the odd hamburger from a cow

466
00:25:59,392 --> 00:26:00,724
that has eaten that grass.

467
00:26:00,726 --> 00:26:05,930
This whole ecosystem
is powered by sunshine.

468
00:26:05,932 --> 00:26:08,599
Narrator: But recent studies
have shed new light

469
00:26:08,601 --> 00:26:12,269
on how life developed
under our sun,

470
00:26:12,271 --> 00:26:16,440
 specifically the role of
ultraviolet light.

471
00:26:16,442 --> 00:26:20,778
U.V.A. Radiation is useful
 for breaking molecules up

472
00:26:20,780 --> 00:26:22,513
 and triggering reactions.

473
00:26:22,515 --> 00:26:24,949
 Maybe that played a role
in the origin of life.

474
00:26:24,951 --> 00:26:27,851
It breaks down
 simple organic molecules,

475
00:26:27,853 --> 00:26:29,353
 and then they can
rebuild themselves

476
00:26:29,355 --> 00:26:31,221
 into things
that are more complex.

477
00:26:31,223 --> 00:26:32,823
You do that over and over again,
 eventually,

478
00:26:32,825 --> 00:26:34,592
you somehow get life.

479
00:26:34,594 --> 00:26:37,962
♪

480
00:26:37,964 --> 00:26:39,630
narrator: Scientists think
life on earth

481
00:26:39,632 --> 00:26:42,866
started around
4 billion years ago...

482
00:26:42,868 --> 00:26:46,637
♪

483
00:26:46,639 --> 00:26:48,806
...A time
when earth's atmosphere

484
00:26:48,808 --> 00:26:50,274
gave little protection.

485
00:26:53,779 --> 00:26:56,914
U.V. Radiation levels
were 100 times higher.

486
00:26:59,218 --> 00:27:00,918
Was u.V. Essential

487
00:27:00,920 --> 00:27:05,789
for the development
of life's code, dna?

488
00:27:05,791 --> 00:27:10,160
We know that life on earth
 stores information in dna

489
00:27:10,162 --> 00:27:13,964
 and then uses that information
to build proteins,

490
00:27:13,966 --> 00:27:16,634
so you have the blueprints
and the bricks.

491
00:27:16,636 --> 00:27:21,171
The blueprints are the dna,
 and the bricks are the protein.

492
00:27:21,173 --> 00:27:24,108
Dartnell: But we think that
 the first life on earth,

493
00:27:24,110 --> 00:27:29,179
we used a chemical
which is much simpler.

494
00:27:29,181 --> 00:27:32,750
Narrator:
 This simpler chemical was rna,

495
00:27:32,752 --> 00:27:37,187
dna's single-stranded
 forefather.

496
00:27:37,189 --> 00:27:40,758
Rna is almost like
a two-for-one offer.

497
00:27:40,760 --> 00:27:43,394
It does both of
the fundamental things

498
00:27:43,396 --> 00:27:48,198
you need for a cell
in the same compound.

499
00:27:48,200 --> 00:27:53,303
 So it was simultaneously
the bricks and the blueprint.

500
00:27:53,305 --> 00:27:56,540
Narrator: Unlike other
molecules, rna is more resistant

501
00:27:56,542 --> 00:27:59,910
to the high u.V. Environment
of early earth,

502
00:27:59,912 --> 00:28:03,747
 allowing it to flourish.

503
00:28:03,749 --> 00:28:07,785
Rna eventually evolved
into dna,

504
00:28:07,787 --> 00:28:09,720
 and life started.

505
00:28:09,722 --> 00:28:11,422
Oluseyi:
To have life on the planet,

506
00:28:11,424 --> 00:28:12,756
one important consideration

507
00:28:12,758 --> 00:28:15,025
is a certain amount of light
 that's going to be needed

508
00:28:15,027 --> 00:28:17,261
and a certain type of light
that's going to be needed.

509
00:28:17,263 --> 00:28:22,032
♪

510
00:28:22,034 --> 00:28:25,502
 narrator: So if all stars emit
some u.V. Radiation,

511
00:28:25,504 --> 00:28:28,972
 can life start around any star?

512
00:28:28,974 --> 00:28:30,407
When we think about
looking for places

513
00:28:30,409 --> 00:28:32,209
that are conducive for life,

514
00:28:32,211 --> 00:28:33,610
we want to find a planet

515
00:28:33,612 --> 00:28:35,879
that might have enough
u.V. Radiation,

516
00:28:35,881 --> 00:28:39,483
 so the star is, you know,
bright enough or close enough

517
00:28:39,485 --> 00:28:42,152
 that's providing enough energy
 to the surface for life,

518
00:28:42,154 --> 00:28:47,057
 but we also don't want to have
 too much u.V. Radiation.

519
00:28:47,059 --> 00:28:50,594
Narrator: It seems you need just
 the right amount of u.V.

520
00:28:50,596 --> 00:28:56,133
♪

521
00:28:56,135 --> 00:28:59,770
 the most common stars in
 the galaxy are red dwarf stars.

522
00:29:02,608 --> 00:29:06,577
If red dwarf stars can harbor
life on planets around them,

523
00:29:06,579 --> 00:29:09,913
there's an awful lot
 of real estate like that

524
00:29:09,915 --> 00:29:12,983
in our galaxy.

525
00:29:12,985 --> 00:29:15,953
Narrator: Red dwarf stars
 could be good for life's chance

526
00:29:15,955 --> 00:29:19,990
of conquering the universe
in a number of ways.

527
00:29:19,992 --> 00:29:22,059
 One, they represent over
three-quarters

528
00:29:22,061 --> 00:29:24,128
of all stars in the universe.

529
00:29:24,130 --> 00:29:26,797
Two, they live for over
a thousand times longer

530
00:29:26,799 --> 00:29:28,265
than sunlike stars,

531
00:29:28,267 --> 00:29:31,001
and, three, they seem to have
 rocky planets around them

532
00:29:31,003 --> 00:29:34,138
much more often
than sunlike stars do.

533
00:29:34,140 --> 00:29:36,140
Narrator:
Those are the pros,

534
00:29:36,142 --> 00:29:39,543
but red dwarf stars
also have cons.

535
00:29:39,545 --> 00:29:44,615
 For instance, they might not be
bright enough for life to begin.

536
00:29:44,617 --> 00:29:47,451
Some of the red dwarf stars
 that we know emit

537
00:29:47,453 --> 00:29:49,920
less ultraviolet light
than the sun.

538
00:29:49,922 --> 00:29:51,855
They don't give off
much u.V. Light at all.

539
00:29:51,857 --> 00:29:53,290
 Maybe on a planet around them,

540
00:29:53,292 --> 00:29:56,527
 there isn't enough energy
to get life started.

541
00:29:56,529 --> 00:30:00,330
Narrator: Red dwarf stars are
also much more temperamental.

542
00:30:00,332 --> 00:30:03,000
They can go from being
 gentle and quiet

543
00:30:03,002 --> 00:30:05,169
 to having violent outbursts...

544
00:30:07,106 --> 00:30:10,007
...Stellar flares.

545
00:30:10,009 --> 00:30:13,310
These types of stars
 have incredibly strong flares.

546
00:30:13,312 --> 00:30:15,012
 That means they're shooting off

547
00:30:15,014 --> 00:30:18,081
 a bunch of energetic particles
and radiation

548
00:30:18,083 --> 00:30:22,853
and light that's baking
the surface of those planets.

549
00:30:22,855 --> 00:30:24,154
 Radebaugh: If the star is just

550
00:30:24,156 --> 00:30:25,656
bombarding the surface
 with u.V.,

551
00:30:25,658 --> 00:30:29,326
then it will destroy all of
those things necessary for life.

552
00:30:29,328 --> 00:30:32,496
 It will actually destroy
 the life itself.

553
00:30:32,498 --> 00:30:37,568
♪

554
00:30:37,570 --> 00:30:39,102
narrator:
These stellar flares

555
00:30:39,104 --> 00:30:41,004
 could strip away
a planet's atmosphere,

556
00:30:41,006 --> 00:30:42,906
 sterilizing the surface.

557
00:30:42,908 --> 00:30:46,777
♪

558
00:30:46,779 --> 00:30:49,446
 more research is needed,
but for now,

559
00:30:49,448 --> 00:30:54,117
the odds of life thriving around
dwarf stars are a toss-up.

560
00:30:54,119 --> 00:30:58,555
♪

561
00:30:58,557 --> 00:31:00,390
so far,
the only thing we know

562
00:31:00,392 --> 00:31:02,426
is that there is one kind
of star

563
00:31:02,428 --> 00:31:05,796
 that's definitely
 right for life --

564
00:31:05,798 --> 00:31:07,397
our sun.

565
00:31:07,399 --> 00:31:10,500
 We know of life in one place in
 the universe, and that's here.

566
00:31:10,502 --> 00:31:12,870
That's earth.

567
00:31:12,872 --> 00:31:18,508
Narrator: Only 4% of stars in
 the universe are like our sun.

568
00:31:18,510 --> 00:31:22,212
 So if life can only get started
around these rare,

569
00:31:22,214 --> 00:31:24,047
medium-sized stars,

570
00:31:24,049 --> 00:31:26,316
 the chances
are not looking good.

571
00:31:26,318 --> 00:31:31,455
♪

572
00:31:31,457 --> 00:31:34,725
 but life may have an ace
up its sleeve.

573
00:31:34,727 --> 00:31:40,097
 What if life can start on
just one planet and then spread?

574
00:31:40,099 --> 00:31:43,300
What if life travels
 across the cosmos

575
00:31:43,302 --> 00:31:47,304
looking for planets to conquer?

576
00:31:53,646 --> 00:31:58,048
[ explosion ]

577
00:31:58,050 --> 00:32:00,217
♪

578
00:32:00,219 --> 00:32:03,086
narrator: Earth is
 our only example of life

579
00:32:03,088 --> 00:32:06,423
 emerging anywhere
 in the universe.

580
00:32:06,425 --> 00:32:11,328
 But what if life on earth
didn't start on earth at all?

581
00:32:11,330 --> 00:32:12,863
There's one idea that life
on earth

582
00:32:12,865 --> 00:32:16,099
 actually didn't get going here
but was delivered from space.

583
00:32:16,101 --> 00:32:19,102
Narrator: Scientists
call this theory panspermia.

584
00:32:21,307 --> 00:32:23,540
 Scharf: The idea of panspermia
 essentially talks

585
00:32:23,542 --> 00:32:28,478
about the transferral of life
throughout the cosmos.

586
00:32:28,480 --> 00:32:31,481
Narrator: We know asteroids
and comets

587
00:32:31,483 --> 00:32:33,583
 carry organic molecules.

588
00:32:33,585 --> 00:32:36,320
But could they carry
life itself?

589
00:32:36,322 --> 00:32:38,455
What if life starts
on one planet?

590
00:32:38,457 --> 00:32:42,993
Can it actually get itself
to a nearby planet?

591
00:32:42,995 --> 00:32:44,394
 Is it possible that meteorites

592
00:32:44,396 --> 00:32:48,465
 could actually transport
living beings?

593
00:32:48,467 --> 00:32:51,835
Narrator: For life to travel
around the cosmos,

594
00:32:51,837 --> 00:32:55,172
 first, it needs to take flight.

595
00:32:55,174 --> 00:33:00,077
 An asteroids is on a collision
course with an inhabited planet.

596
00:33:00,079 --> 00:33:02,779
So what happens if there's
a huge cataclysmic

597
00:33:02,781 --> 00:33:04,081
collision on a planet?

598
00:33:04,083 --> 00:33:06,717
Material is blasted off
into space.

599
00:33:06,719 --> 00:33:10,787
♪

600
00:33:10,789 --> 00:33:12,723
narrator:
The impact might kill life

601
00:33:12,725 --> 00:33:14,257
 on the surface of that planet,

602
00:33:14,259 --> 00:33:19,296
 but it's possible
some bacteria might escape,

603
00:33:19,298 --> 00:33:24,234
 hitching a ride on chunks
 of the planet's surface.

604
00:33:24,236 --> 00:33:26,436
 A meteorite being ejected
from a planet

605
00:33:26,438 --> 00:33:27,871
after an asteroids impact --

606
00:33:27,873 --> 00:33:29,806
 I mean, that's not going
to be an easy ride.

607
00:33:29,808 --> 00:33:32,743
 But it turns out
it's not as bad as you think.

608
00:33:32,745 --> 00:33:35,679
 Some bacteria are
 very, very hard to kill.

609
00:33:35,681 --> 00:33:37,848
Some we don't even know
how to kill.

610
00:33:37,850 --> 00:33:41,084
Even the impact that actually
threw that rock into space --

611
00:33:41,086 --> 00:33:42,886
 the bacteria, no problem.

612
00:33:42,888 --> 00:33:46,857
If those chunks of rock expelled
during asteroids collisions

613
00:33:46,859 --> 00:33:50,360
 could actually hold onto
 viable organisms,

614
00:33:50,362 --> 00:33:52,496
then it really could change
the way

615
00:33:52,498 --> 00:33:58,235
in which we think about life
spreading in the universe.

616
00:33:58,237 --> 00:34:01,071
 Narrator: If the microbes
can survive takeoff,

617
00:34:01,073 --> 00:34:03,840
then they can start
their journey to a new home.

618
00:34:03,842 --> 00:34:06,676
 The odds of life
conquering the universe

619
00:34:06,678 --> 00:34:08,145
seem to be getting better.

620
00:34:08,147 --> 00:34:11,481
 The important question now is,
 how long could that life,

621
00:34:11,483 --> 00:34:13,350
those bacteria,
those microorganisms

622
00:34:13,352 --> 00:34:16,686
 inside that rock,
 survive the space environment?

623
00:34:18,323 --> 00:34:21,291
Narrator: Exposure to
 u.V. Radiation could be fatal,

624
00:34:21,293 --> 00:34:25,095
 killing any life on the surface
of an asteroid.

625
00:34:25,097 --> 00:34:27,831
 But experts think
 that microbial passengers

626
00:34:27,833 --> 00:34:32,169
could still survive
by hiding underground.

627
00:34:32,171 --> 00:34:36,373
 It doesn't take much to shield
 a microorganism from u.V.

628
00:34:36,375 --> 00:34:39,576
Just a little bit of rock,
 and you have enough protection

629
00:34:39,578 --> 00:34:43,380
to just hold on throughout
a journey to the next body,

630
00:34:43,382 --> 00:34:45,849
to your next home.

631
00:34:45,851 --> 00:34:49,619
Narrator: Eventually, they could
 arrive at an uninhabited world

632
00:34:49,621 --> 00:34:52,155
 that's ready and waiting
for life,

633
00:34:52,157 --> 00:34:54,658
but they're in for
 a bumpy landing.

634
00:34:54,660 --> 00:34:58,595
Would the rock burn up coming
 through a planet's atmosphere?

635
00:34:58,597 --> 00:35:02,099
It's in for a hot ride
but only for a few seconds,

636
00:35:02,101 --> 00:35:05,335
 and only the outer layers
of that rock will blow off,

637
00:35:05,337 --> 00:35:08,138
 and then it just falls and hits
 the ground not that fast,

638
00:35:08,140 --> 00:35:11,174
 a couple hundred miles an hour.

639
00:35:11,176 --> 00:35:13,076
 If a human were in there,
that would be bad.

640
00:35:13,078 --> 00:35:15,879
 But for bacteria, no big deal.

641
00:35:15,881 --> 00:35:18,548
Narrator:
The panspermia theory says

642
00:35:18,550 --> 00:35:21,151
life could start on
 just one planet,

643
00:35:21,153 --> 00:35:26,089
 then spread to another planet,
and possibly another.

644
00:35:26,091 --> 00:35:30,560
If we found alien life-forms,
 would they look familiar?

645
00:35:30,562 --> 00:35:32,796
One of the biggest questions
 about finding other life

646
00:35:32,798 --> 00:35:36,933
in the solar system is,
how similar will it be to us?

647
00:35:36,935 --> 00:35:39,836
If it's just like us,
it begs the question,

648
00:35:39,838 --> 00:35:41,771
did we have a common genesis?

649
00:35:41,773 --> 00:35:45,675
 Did we originally
 come from another planet?

650
00:35:45,677 --> 00:35:48,278
Narrator: One radical idea

651
00:35:48,280 --> 00:35:52,149
is that life on earth
came from mars.

652
00:35:52,151 --> 00:35:55,685
Imagine mars
3 1/4, 4 billion years ago.

653
00:35:55,687 --> 00:35:58,955
It was more earthlike then
than earth was at that point.

654
00:35:58,957 --> 00:36:00,790
 The earth was still quite warm.

655
00:36:00,792 --> 00:36:02,826
 Mars actually had cooled
 off faster,

656
00:36:02,828 --> 00:36:04,561
 had a thick atmosphere, water.

657
00:36:04,563 --> 00:36:06,997
Life could've arisen there.

658
00:36:06,999 --> 00:36:10,867
Narrator: Mars has been
hit repeatedly by meteors,

659
00:36:10,869 --> 00:36:15,038
sending chunks of the planet
flying off into space,

660
00:36:15,040 --> 00:36:19,876
 and some of those chunks
have landed here, on earth.

661
00:36:19,878 --> 00:36:23,246
 So this is
a really unusual meteorite.

662
00:36:23,248 --> 00:36:26,716
 It was found near
the city of los angeles,

663
00:36:26,718 --> 00:36:29,252
and we actually know

664
00:36:29,254 --> 00:36:32,389
that it actually came from
 the planet mars,

665
00:36:32,391 --> 00:36:35,425
 and we know that because it has
gases trapped inside it

666
00:36:35,427 --> 00:36:38,028
 that have the exact same
 composition

667
00:36:38,030 --> 00:36:39,396
as the martian atmosphere.

668
00:36:39,398 --> 00:36:40,764
There's been a lot of transit

669
00:36:40,766 --> 00:36:43,466
between meteor strikes
hitting mars and then earth.

670
00:36:43,468 --> 00:36:45,035
There's a little bit of mars
on earth.

671
00:36:45,037 --> 00:36:47,370
There's a little bit
 of earth on mars.

672
00:36:47,372 --> 00:36:51,308
It's possible that life
started on mars

673
00:36:51,310 --> 00:36:56,913
and was transferred to earth
inside of a meteorite.

674
00:36:56,915 --> 00:36:59,749
When you think about it,
maybe we're the immigrants.

675
00:36:59,751 --> 00:37:01,284
We are the martians.

676
00:37:01,286 --> 00:37:05,422
Life on earth started on mars
 and got transferred here.

677
00:37:05,424 --> 00:37:09,359
♪

678
00:37:09,361 --> 00:37:11,461
narrator:
Panspermia could allow life

679
00:37:11,463 --> 00:37:13,463
to spread from planet to planet,

680
00:37:13,465 --> 00:37:15,532
conquering our solar system,

681
00:37:15,534 --> 00:37:19,869
but what about
even greater distances?

682
00:37:19,871 --> 00:37:24,274
 In 2017, the cigar-shaped
space rock 'oumuamua

683
00:37:24,276 --> 00:37:26,243
appeared in our solar system.

684
00:37:26,245 --> 00:37:28,478
It came from interstellar space,

685
00:37:28,480 --> 00:37:32,549
and experts think it could be
 carrying organic matter.

686
00:37:32,551 --> 00:37:34,651
One of the fascinating
things about 'oumuamua

687
00:37:34,653 --> 00:37:36,853
 is it has sort of
a reddened surface.

688
00:37:36,855 --> 00:37:38,121
Now that could actually
partially be

689
00:37:38,123 --> 00:37:40,457
 from the presence
of organic molecules.

690
00:37:40,459 --> 00:37:42,626
Narrator: Could life survive

691
00:37:42,628 --> 00:37:45,962
interstellar
or even intergalactic travel?

692
00:37:45,964 --> 00:37:49,766
 Whether or not this is an easy
way to transfer life around

693
00:37:49,768 --> 00:37:52,636
 in the universe,
it's still an open question.

694
00:37:52,638 --> 00:37:55,405
 The possibility of transferring
life from star system

695
00:37:55,407 --> 00:37:59,009
to star system
seems a little bit remote.

696
00:37:59,011 --> 00:38:00,677
Narrator:
The immense distances

697
00:38:00,679 --> 00:38:02,479
 and dangers
of interstellar travel

698
00:38:02,481 --> 00:38:04,447
 would be hard to survive.

699
00:38:04,449 --> 00:38:08,251
Some experts think there is
 one way for life

700
00:38:08,253 --> 00:38:11,821
 to conquer the universe,

701
00:38:11,823 --> 00:38:14,991
but it won't be life
as we know it.

702
00:38:22,467 --> 00:38:26,870
[ explosion ]

703
00:38:26,872 --> 00:38:31,041
 narrator: The universe is
unimaginably large.

704
00:38:31,043 --> 00:38:35,111
Many experts believe
 there is life out there.

705
00:38:35,113 --> 00:38:37,347
We just have to go find it.

706
00:38:37,349 --> 00:38:40,617
Oluseyi: One of the things
I love about being a human

707
00:38:40,619 --> 00:38:44,621
 is the fact that
I'm born with this curiosity.

708
00:38:44,623 --> 00:38:46,489
This curiosity drives us to
 explore -- explore earth,

709
00:38:46,491 --> 00:38:50,060
 explore our solar system
and beyond into the galaxy,

710
00:38:50,062 --> 00:38:52,896
look for other life-forms.

711
00:38:52,898 --> 00:38:55,098
Narrator:
But with current technology,

712
00:38:55,100 --> 00:38:59,369
it would take thousands of years
 just to reach the nearest star.

713
00:38:59,371 --> 00:39:03,106
It's unlikely humans
will ever leave our galaxy.

714
00:39:05,644 --> 00:39:10,113
If life one day does spread
from earth into the cosmos,

715
00:39:10,115 --> 00:39:12,549
 it's probably not just going to
 be a bunch of meat bags,

716
00:39:12,551 --> 00:39:16,953
like us, but other forms of life
that are more suited

717
00:39:16,955 --> 00:39:21,191
 for interstellar
 and intergalactic travel.

718
00:39:21,193 --> 00:39:24,027
Narrator: Our fragile bodies are
not suited to the distances

719
00:39:24,029 --> 00:39:28,565
 and dangers
of interstellar travel.

720
00:39:28,567 --> 00:39:33,169
 Machine life may be more robust
for traveling between planets

721
00:39:33,171 --> 00:39:36,406
 and between stars
than biological life.

722
00:39:38,677 --> 00:39:40,243
There are a lot of scientists
 that think

723
00:39:40,245 --> 00:39:43,613
 when we encounter aliens,
 we won't be encountering them.

724
00:39:43,615 --> 00:39:45,215
We'll be encountering
their machines

725
00:39:45,217 --> 00:39:48,151
because we can build machines
 that can last a million years,

726
00:39:48,153 --> 00:39:49,586
go from one star to the next.

727
00:39:49,588 --> 00:39:51,554
 It's much easier
than transporting us,

728
00:39:51,556 --> 00:39:55,392
fragile gloppy bags of meat.
And so if we go out into space,

729
00:39:55,394 --> 00:40:00,897
we're more likely to find robots
than we are biological life.

730
00:40:00,899 --> 00:40:03,767
 Narrator: For humanity to
discover alien life,

731
00:40:03,769 --> 00:40:08,238
 humanity itself may have
to evolve

732
00:40:08,240 --> 00:40:13,510
from biological life
to artificial life.

733
00:40:13,512 --> 00:40:16,012
Oluseyi: What's really ironic
here is that

734
00:40:16,014 --> 00:40:19,949
 while we're figuring out
the origin of life on earth,

735
00:40:19,951 --> 00:40:23,586
we humans could be inventing
a form of life on our own,

736
00:40:23,588 --> 00:40:27,090
 and that is what we call
 artificial intelligence.

737
00:40:27,092 --> 00:40:31,661
 The development of a.I.,
self-replicating machines even,

738
00:40:31,663 --> 00:40:34,631
 may very well be
just the next key transition

739
00:40:34,633 --> 00:40:37,033
in our evolutionary history.

740
00:40:39,871 --> 00:40:43,540
Narrator:
 Could a superintelligent
 self-replicating machine

741
00:40:43,542 --> 00:40:46,943
conquer the universe?

742
00:40:46,945 --> 00:40:51,815
Maybe this a.I. Can fashion
 its own machines,

743
00:40:51,817 --> 00:40:55,285
create factories to create
 resources to replicate itself,

744
00:40:55,287 --> 00:40:58,721
create ships
 that will allow it travel

745
00:40:58,723 --> 00:41:01,024
from one place
in the universe to another.

746
00:41:03,862 --> 00:41:07,797
 Narrator: But would a.I.
Represent a new form of life?

747
00:41:07,799 --> 00:41:09,132
Thaller:
I think the answer is yes.

748
00:41:09,134 --> 00:41:11,067
I think it actually goes on
 from there.

749
00:41:11,069 --> 00:41:12,969
 I think artificial intelligence
might be

750
00:41:12,971 --> 00:41:15,672
 the next necessary stage
in evolution.

751
00:41:15,674 --> 00:41:19,209
We made the computers.
They are our children.

752
00:41:19,211 --> 00:41:24,380
I think of life as a process
 that can retain its complexity

753
00:41:24,382 --> 00:41:29,352
and reproduce,
so bacteria are life.

754
00:41:29,354 --> 00:41:33,356
 Humans are life,
 and some future creation

755
00:41:33,358 --> 00:41:34,924
 of advanced
artificial intelligence

756
00:41:34,926 --> 00:41:38,661
 that can do those things
should also count as life.

757
00:41:41,600 --> 00:41:44,267
Narrator:
Life could take many forms,

758
00:41:44,269 --> 00:41:47,604
and in such a vast universe,

759
00:41:47,606 --> 00:41:52,609
it could be that life
is inevitable.

760
00:41:52,611 --> 00:41:55,044
With all those stars
and all those planets,

761
00:41:55,046 --> 00:41:58,147
 I think, without a doubt,
there is a good chance

762
00:41:58,149 --> 00:42:02,285
that life has developed
elsewhere in our universe.

763
00:42:02,287 --> 00:42:05,421
Must life happen
 in our universe?

764
00:42:05,423 --> 00:42:10,660
 Is it an inevitable consequence
of processes in operation?

765
00:42:10,662 --> 00:42:13,296
 Maybe, maybe not.

766
00:42:16,668 --> 00:42:21,538
Narrator: Until we find it,
we won't know for sure

767
00:42:21,540 --> 00:42:25,408
 whether life can conquer
the universe.

768
00:42:25,410 --> 00:42:28,478
♪