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Earth...
A planet defined by life.
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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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But is Earth unique?
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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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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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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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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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Life has conquered our planet,
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but can life conquer
the universe?
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captions by vitac...
www.Vitac.Com
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captions paid for by
discovery communications
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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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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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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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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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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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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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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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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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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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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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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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The question is,
what exactly are we looking for?
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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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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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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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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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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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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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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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So it comes down
to a numbers game.
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It's about statistics and
probabilities and likelihoods.
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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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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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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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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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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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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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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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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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these elements are blasted out
into space in a supernova,
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spreading the ingredients
for life out into the cosmos.
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We, the Earth, our solar system,
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all the ingredients
that make us,
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us were forged in nuclear fires.
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So the death of stars
leads to the birth of life.
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Those key ingredients
include oxygen,
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nitrogen, sulfur,
and phosphorus,
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but the element most central
to life as we know it is carbon.
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All life as we know it on Earth
is based on carbon.
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Carbon forms the structure,
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the architecture
of our living molecules.
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Carbon is
an incredibly versatile
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building material.
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It can bond with other elements
to form long-chain molecules,
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each with different properties.
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As an element, it seems to be
capable of producing
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a vast and complex chemistry,
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and that complex chemistry
is what we find in life.
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We call this organic chemistry.
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But getting from
basic organic molecules
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to complex life-forms
is a big leap.
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We don't really have
the slightest idea,
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00:12:40,810 --> 00:12:45,610
to be honest, about how life
on Earth got started.
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00:12:45,620 --> 00:12:49,320
A really big question
is, how do you go from a mix
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of relatively simple organic
molecules to a living system?
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We know it all starts
with basic elements created
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in massive quantities...
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By the death of stars.
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But how do you start connecting
those Lego bricks together
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to build that first cell?
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The short answer is,
"we don't know,"
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but we have some ideas
of potential steps.
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Chains of organic molecules
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become more and more complex.
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Amino acids form proteins.
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Fatty acids form phospholipids,
which makes cell membranes.
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Nucleic acids form DNA,
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the molecule that stores
genetic information.
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Eventually,
a simple cell emerges.
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So all of the bits you need
to plug together
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to build a cell from scratch
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seems to exist in outer space.
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We found organic compounds
everywhere.
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They're all over the place...
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Planets, comets, gas clouds.
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The very basic
ingredients of life
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available elsewhere
in our solar system,
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00:14:05,430 --> 00:14:08,100
so there could be life
everywhere.
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00:14:11,300 --> 00:14:12,970
In 2018,
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00:14:12,970 --> 00:14:16,640
NASA announces it's found
organic molecules
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on another planet,
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00:14:18,740 --> 00:14:23,980
a planet we've always suspected
of harboring alien life...
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00:14:23,980 --> 00:14:26,380
Mars.
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00:14:26,380 --> 00:14:28,750
So whenever NASA has a
press conference, and they say,
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00:14:28,750 --> 00:14:31,720
"hey, I have some results
to report on about mars,"
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00:14:31,720 --> 00:14:33,420
everyone goes nuts.
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00:14:33,420 --> 00:14:36,060
The internet goes mad.
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00:14:36,060 --> 00:14:38,590
Maybe we've got photograph
evidence of the green men
256
00:14:38,590 --> 00:14:40,730
in a UFO.
257
00:14:40,730 --> 00:14:42,330
This time, it's the martians.
258
00:14:42,330 --> 00:14:45,400
They're going to tell us
they found a martian.
259
00:14:45,400 --> 00:14:47,570
The world listens
'cause everyone wants to know.
260
00:14:47,570 --> 00:14:49,270
Everyone asks the question,
261
00:14:49,270 --> 00:14:51,010
"have we found evidence
of life?"
262
00:14:53,310 --> 00:14:54,740
For 6 years,
263
00:14:54,740 --> 00:14:57,580
the mars curiosity
rover has been exploring
264
00:14:57,580 --> 00:14:59,680
a region called gale crater,
265
00:14:59,680 --> 00:15:02,580
hunting for signs of
ancient life.
266
00:15:04,920 --> 00:15:08,260
A bit like
fossil-hunting on Earth.
267
00:15:08,260 --> 00:15:10,560
Gale crater is not unlike
places on Earth
268
00:15:10,560 --> 00:15:13,430
that can preserve fossils,
so a really good example of this
269
00:15:13,430 --> 00:15:17,230
would be the petrified forest
in Arizona.
270
00:15:17,230 --> 00:15:21,670
This looks like a piece of wood,
but in fact, it is stone.
271
00:15:21,670 --> 00:15:24,970
It is all stone,
but it used to be a tree.
272
00:15:24,970 --> 00:15:29,480
This fossil lived
200 million years ago.
273
00:15:29,480 --> 00:15:31,350
This patch of desert in Arizona
274
00:15:31,350 --> 00:15:33,210
once looked
completely different.
275
00:15:35,380 --> 00:15:37,720
This landscape looks
very dry right now,
276
00:15:37,720 --> 00:15:39,090
but 200 million years ago,
277
00:15:39,090 --> 00:15:44,020
it was wet swampland
with trees and flowing water.
278
00:15:45,630 --> 00:15:47,230
Like the petrified forest,
279
00:15:47,230 --> 00:15:51,100
mars has also changed over time.
280
00:15:51,100 --> 00:15:55,870
Gale crater was once a lake bed
filled with fresh water.
281
00:15:55,870 --> 00:15:59,640
And it was just so exciting
because we knew then
282
00:15:59,640 --> 00:16:03,210
that we had landed
right on top of an environment
283
00:16:03,210 --> 00:16:05,510
that once had tons
of flowing water
284
00:16:05,510 --> 00:16:08,250
and could very well have
preserved organic materials,
285
00:16:08,250 --> 00:16:11,250
even though it looks very barren
and desolate to our eyes.
286
00:16:13,720 --> 00:16:15,220
In 2018,
287
00:16:15,220 --> 00:16:18,430
curiosity drills into
this ancient martian lake
288
00:16:18,430 --> 00:16:21,260
and discovers organic molecules.
289
00:16:24,500 --> 00:16:27,670
Finding organics on mars
is so exciting
290
00:16:27,670 --> 00:16:29,470
just because, I mean, wow.
291
00:16:29,470 --> 00:16:31,640
That is... those are
the building blocks of life,
292
00:16:31,640 --> 00:16:34,040
not just the elements,
but actual molecules.
293
00:16:34,040 --> 00:16:36,680
There was a wave of excitement
294
00:16:36,680 --> 00:16:38,850
after the announcement
of organics
295
00:16:38,850 --> 00:16:41,350
found on mars
and complex organics.
296
00:16:41,350 --> 00:16:43,980
It's not totally indicative
that life is there,
297
00:16:43,990 --> 00:16:46,520
but it's a really good
telltale sign
298
00:16:46,520 --> 00:16:51,560
that there may be
possibly life-forms on mars.
299
00:16:51,560 --> 00:16:54,630
The results aren't
proof of martians,
300
00:16:54,630 --> 00:16:58,830
but the ancient lake bed
is evidence that the red planet
301
00:16:58,830 --> 00:17:02,870
once had something else
crucial for life...
302
00:17:02,870 --> 00:17:04,200
Liquid water.
303
00:17:07,580 --> 00:17:09,640
It's one thing if you have
all these ingredients
304
00:17:09,650 --> 00:17:11,110
lying around for life.
305
00:17:11,110 --> 00:17:12,710
You could have, you know,
carbon over here and hydrogen
306
00:17:12,720 --> 00:17:15,050
over here,
maybe methane or whatever.
307
00:17:15,050 --> 00:17:16,550
You have to mix them together,
308
00:17:16,550 --> 00:17:21,160
so you need something for them
to be in, a medium of some sort.
309
00:17:21,160 --> 00:17:22,890
Life needs a liquid
310
00:17:22,890 --> 00:17:26,860
to mix essential chemicals
together.
311
00:17:26,860 --> 00:17:28,230
We're used to thinking of Earth
312
00:17:28,230 --> 00:17:33,230
as the only water world
in our solar system,
313
00:17:33,240 --> 00:17:35,940
but new evidence says
otherwise...
314
00:17:38,640 --> 00:17:42,140
As extraterrestrial visitors
315
00:17:42,140 --> 00:17:46,550
carrying liquid water
from outer space reveal.
316
00:18:00,700 --> 00:18:02,500
It's no coincidence
317
00:18:02,500 --> 00:18:05,430
our blue planet is
a water world.
318
00:18:05,430 --> 00:18:09,600
There are more than
366 million trillion gallons
319
00:18:09,610 --> 00:18:12,610
of water on Earth.
320
00:18:12,610 --> 00:18:16,410
It even makes up
60% of our bodies.
321
00:18:16,410 --> 00:18:18,610
I think life on Earth
could be easily described
322
00:18:18,610 --> 00:18:20,910
as water chemistry.
323
00:18:20,920 --> 00:18:24,590
That is the essential feature
of life on Earth.
324
00:18:24,590 --> 00:18:27,050
Some is locked up in ice caps
325
00:18:27,060 --> 00:18:30,020
or as vapor in the air,
326
00:18:30,030 --> 00:18:35,000
but 96% of liquid water
is in our oceans.
327
00:18:35,000 --> 00:18:37,260
Well, Earth is really special.
328
00:18:37,270 --> 00:18:39,970
There's no other place like it
that we've found.
329
00:18:39,970 --> 00:18:43,670
It's a pretty substantial planet
with liquid water
330
00:18:43,670 --> 00:18:45,770
covering 70% of the surface.
331
00:18:45,770 --> 00:18:48,440
All life on the Earth requires
bodies of water
332
00:18:48,440 --> 00:18:49,680
in order to survive.
333
00:18:49,680 --> 00:18:51,310
No water, no life.
334
00:18:52,780 --> 00:18:56,850
Water is what chemists
call a solvent,
335
00:18:56,850 --> 00:19:00,520
and it's the best solvent
we know of.
336
00:19:00,520 --> 00:19:04,120
It can dissolve more substances
than any other liquid,
337
00:19:04,130 --> 00:19:07,660
allowing molecules
to mix and interact.
338
00:19:07,660 --> 00:19:10,960
Wherever water goes,
it transports
339
00:19:10,970 --> 00:19:15,070
valuable chemicals, minerals,
and nutrients.
340
00:19:15,070 --> 00:19:16,540
If there was no liquid,
341
00:19:16,540 --> 00:19:18,510
things would just sit around
separately.
342
00:19:18,510 --> 00:19:20,840
You need this constant
interaction,
343
00:19:20,840 --> 00:19:23,310
and you need
a different chemical mix,
344
00:19:23,310 --> 00:19:25,550
and water does all of that.
345
00:19:27,550 --> 00:19:31,220
And so a lot of our searches
for lifelike planets,
346
00:19:31,220 --> 00:19:34,620
or earthlike planets,
outside our solar system
347
00:19:34,620 --> 00:19:38,130
are based on this sort of
primary assumption
348
00:19:38,130 --> 00:19:40,030
that we need liquid water.
349
00:19:42,260 --> 00:19:44,870
We've long thought
Earth has liquid water
350
00:19:44,870 --> 00:19:49,640
because of its unique position
in the solar system.
351
00:19:49,640 --> 00:19:53,010
It's right in this zone that
we call the habitable zone
352
00:19:53,010 --> 00:19:56,580
where the sunlight
can support liquid water
353
00:19:56,580 --> 00:19:58,280
on the surface of the planet.
354
00:20:01,680 --> 00:20:04,120
But we have now
discovered that liquid water
355
00:20:04,120 --> 00:20:07,450
might exist in places
we never expected.
356
00:20:10,060 --> 00:20:14,800
In 1998, a meteorite crash-lands
in Texas.
357
00:20:19,370 --> 00:20:22,300
Today, scientists
at Arizona state university
358
00:20:22,300 --> 00:20:26,040
are still studying its secrets.
359
00:20:26,040 --> 00:20:27,810
We had no idea
that it would contain
360
00:20:27,810 --> 00:20:31,110
this really,
really spectacular finding.
361
00:20:31,110 --> 00:20:35,080
It contains
a mysterious purple mineral.
362
00:20:35,080 --> 00:20:39,120
The exotic color comes from
exposure to cosmic radiation,
363
00:20:39,120 --> 00:20:42,890
but the compound itself
is very ordinary.
364
00:20:42,890 --> 00:20:44,860
It's actually sodium chloride,
365
00:20:44,860 --> 00:20:48,330
which is essentially
the same mineral as table salt,
366
00:20:48,330 --> 00:20:51,370
but what's really cool
is that it actually contains
367
00:20:51,370 --> 00:20:54,130
little globules of liquid water,
368
00:20:54,140 --> 00:20:57,600
and that liquid water
was trapped in these crystals
369
00:20:57,610 --> 00:21:01,010
4 1/2 billion years ago.
370
00:21:01,010 --> 00:21:04,110
In 2018, scientists
reexamined the crystals
371
00:21:04,110 --> 00:21:08,380
and discovered the liquid water
wasn't traveling alone.
372
00:21:08,380 --> 00:21:11,820
We've now actually found
organic compounds in association
373
00:21:11,820 --> 00:21:15,390
with this liquid water
in these salt crystals,
374
00:21:15,390 --> 00:21:17,860
and that's something
that's really new
375
00:21:17,860 --> 00:21:20,090
and really spectacular.
376
00:21:22,600 --> 00:21:24,360
We actually found amino acids,
377
00:21:24,370 --> 00:21:27,770
the building blocks of all
of our proteins, even our DNA,
378
00:21:27,770 --> 00:21:29,400
and we found liquid water,
379
00:21:29,410 --> 00:21:32,540
the very building blocks
of life, inside a meteorite.
380
00:21:34,780 --> 00:21:36,880
So could life exist
381
00:21:36,880 --> 00:21:38,980
somewhere else
in our solar system?
382
00:21:42,790 --> 00:21:47,090
A NASA mission to Saturn
turned up some shocking results.
383
00:21:47,090 --> 00:21:52,190
The Cassini space probe flew
beneath Saturn�s moon Enceladus.
384
00:21:52,190 --> 00:21:54,800
Enceladus, no one cared about.
385
00:21:54,800 --> 00:22:01,200
It was a tiny, little snowball
of a world.
386
00:22:01,200 --> 00:22:04,240
But Enceladus
surprised everyone.
387
00:22:06,810 --> 00:22:11,040
Geysers of liquid water,
dozens of them,
388
00:22:11,050 --> 00:22:14,180
blast out of trenches
along the moon's surface,
389
00:22:14,180 --> 00:22:17,550
coming from
a vast subsurface ocean.
390
00:22:21,520 --> 00:22:24,520
Oceans on Earth
are full of life.
391
00:22:27,760 --> 00:22:30,800
Could the same be true
of Enceladus?
392
00:22:30,800 --> 00:22:33,300
I'm a big fan of Enceladus.
393
00:22:33,300 --> 00:22:37,070
I think it's by far and away
the best place to go
394
00:22:37,070 --> 00:22:39,210
to search for evidence of life.
395
00:22:39,210 --> 00:22:40,670
In 2018,
396
00:22:40,680 --> 00:22:43,710
researchers analyzing
the Cassini data
397
00:22:43,710 --> 00:22:46,350
discovered that the plumes
of Enceladus
398
00:22:46,350 --> 00:22:49,380
contain
complex organic molecules.
399
00:22:49,390 --> 00:22:52,920
Just simple molecules,
we find those, like methane,
400
00:22:52,920 --> 00:22:55,320
but the Cassini results
are showing that there are
401
00:22:55,320 --> 00:22:59,960
these more complex, larger
organic molecules as well.
402
00:22:59,960 --> 00:23:03,030
This is the first ever
detection of complex organics
403
00:23:03,030 --> 00:23:05,970
on an extraterrestrial
water world.
404
00:23:05,970 --> 00:23:09,500
All of a sudden,
here's water jetting out,
405
00:23:09,510 --> 00:23:13,740
carrying organic material, all
the ingredients needed for life.
406
00:23:13,740 --> 00:23:17,740
It was, like, too good
to be true.
407
00:23:17,750 --> 00:23:20,180
But Enceladus isn't
the only small world
408
00:23:20,180 --> 00:23:22,150
with a subsurface ocean.
409
00:23:22,150 --> 00:23:26,820
Other moons and dwarf planets
have liquid water, too.
410
00:23:26,820 --> 00:23:29,120
We think the most important
thing for life to form
411
00:23:29,120 --> 00:23:30,720
is the presence of liquid water,
412
00:23:30,730 --> 00:23:33,190
and our solar system
seems to be full of it.
413
00:23:35,560 --> 00:23:38,330
The discovery of liquid water
414
00:23:38,330 --> 00:23:40,070
in the outer solar system
415
00:23:40,070 --> 00:23:46,640
changes the rules of how life
might originate in the universe.
416
00:23:50,250 --> 00:23:51,750
Across the universe,
417
00:23:51,750 --> 00:23:56,580
alien life could be hiding
underneath the surface.
418
00:23:56,590 --> 00:24:00,290
Internal water oceans are
far more common
419
00:24:00,290 --> 00:24:03,620
than surface water oceans,
420
00:24:03,630 --> 00:24:07,130
so if there is a lot of life
out there in the universe,
421
00:24:07,130 --> 00:24:11,400
chances are it's in an internal
ocean under miles of ice.
422
00:24:13,500 --> 00:24:15,200
Who knows what might be lurking
423
00:24:15,200 --> 00:24:18,470
inside icy exoworlds?
424
00:24:18,470 --> 00:24:22,080
There may be jellyfish
and octopuses all over the place
425
00:24:22,080 --> 00:24:25,280
in exomoons and exoplanets
under ice
426
00:24:25,280 --> 00:24:28,920
that have civilizations
that we just don't know about.
427
00:24:28,920 --> 00:24:31,020
Finding liquid water oceans
428
00:24:31,020 --> 00:24:33,720
could open up a world
of possibilities.
429
00:24:35,960 --> 00:24:37,790
If you're not excited about
430
00:24:37,790 --> 00:24:41,030
intelligent extraterrestrial
octopus civilians,
431
00:24:41,030 --> 00:24:42,760
I don't know what to say.
432
00:24:45,000 --> 00:24:47,870
The chances of finding
life in our solar system
433
00:24:47,870 --> 00:24:49,940
just got a heck of a lot better.
434
00:24:53,280 --> 00:24:57,340
Building blocks
and liquid water are common,
435
00:24:57,350 --> 00:25:00,180
but you need more than
just these two conditions
436
00:25:00,180 --> 00:25:02,120
for life to take hold.
437
00:25:02,120 --> 00:25:04,780
Life needs a spark.
438
00:25:04,790 --> 00:25:06,820
Life appears to need
some form of energy
439
00:25:06,820 --> 00:25:08,890
to actually get
the molecules interacting.
440
00:25:08,890 --> 00:25:10,990
One thing that may have helped
kick-start life on Earth
441
00:25:10,990 --> 00:25:13,560
is ultraviolet radiation
from the sun.
442
00:25:13,560 --> 00:25:17,100
Ultraviolet light
is emitted by all stars.
443
00:25:17,100 --> 00:25:21,400
There are billions of stars
in our galaxy.
444
00:25:21,400 --> 00:25:24,940
Can life get started
around any star,
445
00:25:24,940 --> 00:25:29,140
or is our sun unique?
446
00:25:39,890 --> 00:25:43,620
Earth is a solar-powered planet.
447
00:25:43,630 --> 00:25:47,390
At the bottom of the food chain,
plants use photosynthesis
448
00:25:47,400 --> 00:25:50,900
to convert sunlight
into chemical energy...
449
00:25:50,900 --> 00:25:53,100
Food for the rest of us.
450
00:25:53,100 --> 00:25:56,770
I like eating
both grass, essentially wheat,
451
00:25:56,770 --> 00:25:59,410
and I also fancy
the odd hamburger from a cow
452
00:25:59,410 --> 00:26:00,740
that has eaten that grass.
453
00:26:00,740 --> 00:26:05,950
This whole ecosystem
is powered by sunshine.
454
00:26:05,950 --> 00:26:08,620
But recent studies
have shed new light
455
00:26:08,620 --> 00:26:12,290
on how life developed
under our sun,
456
00:26:12,290 --> 00:26:16,460
specifically the role of
ultraviolet light.
457
00:26:16,460 --> 00:26:20,790
U.V.A. Radiation is useful
for breaking molecules up
458
00:26:20,800 --> 00:26:22,530
and triggering reactions.
459
00:26:22,530 --> 00:26:24,970
Maybe that played a role
in the origin of life.
460
00:26:24,970 --> 00:26:27,870
It breaks down
simple organic molecules,
461
00:26:27,870 --> 00:26:29,370
and then they can
rebuild themselves
462
00:26:29,370 --> 00:26:31,240
into things
that are more complex.
463
00:26:31,240 --> 00:26:32,840
You do that over and over again,
eventually,
464
00:26:32,840 --> 00:26:34,610
you somehow get life.
465
00:26:37,980 --> 00:26:39,650
Scientists think life on Earth
466
00:26:39,650 --> 00:26:42,880
started around
4 billion years ago...
467
00:26:46,660 --> 00:26:48,820
A time when Earth's atmosphere
468
00:26:48,820 --> 00:26:50,290
gave little protection.
469
00:26:53,800 --> 00:26:56,930
U.V. Radiation levels
were 100 times higher.
470
00:26:59,230 --> 00:27:00,930
Was u.V. Essential
471
00:27:00,940 --> 00:27:05,810
for the development
of life's code, DNA?
472
00:27:05,810 --> 00:27:10,180
We know that life on Earth
stores information in DNA
473
00:27:10,180 --> 00:27:13,980
and then uses that information
to build proteins,
474
00:27:13,980 --> 00:27:16,650
so you have the blueprints
and the bricks.
475
00:27:16,650 --> 00:27:21,190
The blueprints are the DNA,
and the bricks are the protein.
476
00:27:21,190 --> 00:27:24,120
But we think that
the first life on Earth,
477
00:27:24,130 --> 00:27:29,200
we used a chemical
which is much simpler.
478
00:27:29,200 --> 00:27:32,770
This simpler chemical was RNA,
479
00:27:32,770 --> 00:27:37,200
DNA�s single-stranded
forefather.
480
00:27:37,210 --> 00:27:40,770
RNA is almost like
a two-for-one offer.
481
00:27:40,780 --> 00:27:43,410
It does both of
the fundamental things
482
00:27:43,410 --> 00:27:48,210
you need for a cell
in the same compound.
483
00:27:48,220 --> 00:27:53,320
So it was simultaneously
the bricks and the blueprint.
484
00:27:53,320 --> 00:27:56,560
Unlike other
molecules, RNA is more resistant
485
00:27:56,560 --> 00:27:59,930
to the high u.V. Environment
of early Earth,
486
00:27:59,930 --> 00:28:03,760
allowing it to flourish.
487
00:28:03,770 --> 00:28:07,800
RNA eventually evolved into DNA,
488
00:28:07,800 --> 00:28:09,740
and life started.
489
00:28:09,740 --> 00:28:11,440
To have life on the planet,
490
00:28:11,440 --> 00:28:12,770
one important consideration
491
00:28:12,770 --> 00:28:15,040
is a certain amount of light
that's going to be needed
492
00:28:15,040 --> 00:28:17,280
and a certain type of light
that's going to be needed.
493
00:28:22,050 --> 00:28:25,520
So if all stars emit
some u.V. Radiation,
494
00:28:25,520 --> 00:28:28,990
can life start around any star?
495
00:28:28,990 --> 00:28:30,420
When we think about
looking for places
496
00:28:30,430 --> 00:28:32,230
that are conducive for life,
497
00:28:32,230 --> 00:28:33,630
we want to find a planet
498
00:28:33,630 --> 00:28:35,900
that might have enough
u.V. Radiation,
499
00:28:35,900 --> 00:28:39,500
so the star is, you know,
bright enough or close enough
500
00:28:39,500 --> 00:28:42,170
that's providing enough energy
to the surface for life,
501
00:28:42,170 --> 00:28:47,070
but we also don't want to have
too much u.V. Radiation.
502
00:28:47,080 --> 00:28:50,610
It seems you need just
the right amount of u.V.
503
00:28:56,150 --> 00:28:59,790
The most common stars in
the galaxy are red dwarf stars.
504
00:29:02,620 --> 00:29:06,590
If red dwarf stars can harbor
life on planets around them,
505
00:29:06,600 --> 00:29:09,930
there's an awful lot
of real estate like that
506
00:29:09,930 --> 00:29:13,000
in our galaxy.
507
00:29:13,000 --> 00:29:15,970
Red dwarf stars
could be good for life's chance
508
00:29:15,970 --> 00:29:20,010
of conquering the universe
in a number of ways.
509
00:29:20,010 --> 00:29:22,080
One, they represent over
three-quarters
510
00:29:22,080 --> 00:29:24,140
of all stars in the universe.
511
00:29:24,150 --> 00:29:26,810
Two, they live for over
a thousand times longer
512
00:29:26,820 --> 00:29:28,280
than sunlike stars,
513
00:29:28,280 --> 00:29:31,020
and, three, they seem to have
rocky planets around them
514
00:29:31,020 --> 00:29:34,150
much more often
than sunlike stars do.
515
00:29:34,160 --> 00:29:36,160
Those are the pros,
516
00:29:36,160 --> 00:29:39,560
but red dwarf stars
also have cons.
517
00:29:39,560 --> 00:29:44,630
For instance, they might not be
bright enough for life to begin.
518
00:29:44,630 --> 00:29:47,470
Some of the red dwarf stars
that we know emit
519
00:29:47,470 --> 00:29:49,940
less ultraviolet light
than the sun.
520
00:29:49,940 --> 00:29:51,870
They don't give off
much u.V. Light at all.
521
00:29:51,870 --> 00:29:53,310
Maybe on a planet around them,
522
00:29:53,310 --> 00:29:56,540
there isn't enough energy
to get life started.
523
00:29:56,550 --> 00:30:00,350
Red dwarf stars are
also much more temperamental.
524
00:30:00,350 --> 00:30:03,020
They can go from being
gentle and quiet
525
00:30:03,020 --> 00:30:05,190
to having violent outbursts...
526
00:30:07,120 --> 00:30:10,020
Stellar flares.
527
00:30:10,030 --> 00:30:13,330
These types of stars
have incredibly strong flares.
528
00:30:13,330 --> 00:30:15,030
That means they're shooting off
529
00:30:15,030 --> 00:30:18,100
a bunch of energetic particles
and radiation
530
00:30:18,100 --> 00:30:22,870
and light that's baking
the surface of those planets.
531
00:30:22,870 --> 00:30:24,170
If the star is just
532
00:30:24,170 --> 00:30:25,670
bombarding the surface
with u.V.,
533
00:30:25,670 --> 00:30:29,340
then it will destroy all of
those things necessary for life.
534
00:30:29,340 --> 00:30:32,510
It will actually destroy
the life itself.
535
00:30:37,590 --> 00:30:39,120
These stellar flares
536
00:30:39,120 --> 00:30:41,020
could strip away
a planet's atmosphere,
537
00:30:41,020 --> 00:30:42,920
sterilizing the surface.
538
00:30:46,800 --> 00:30:49,460
More research is needed,
but for now,
539
00:30:49,460 --> 00:30:54,130
the odds of life thriving around
dwarf stars are a toss-up.
540
00:30:58,570 --> 00:31:00,410
So far, the only thing we know
541
00:31:00,410 --> 00:31:02,440
is that there is one kind
of star
542
00:31:02,440 --> 00:31:05,810
that's definitely
right for life...
543
00:31:05,810 --> 00:31:07,410
Our sun.
544
00:31:07,420 --> 00:31:10,520
We know of life in one place in
the universe, and that's here.
545
00:31:10,520 --> 00:31:12,890
That's Earth.
546
00:31:12,890 --> 00:31:18,520
Only 4% of stars in
the universe are like our sun.
547
00:31:18,530 --> 00:31:22,230
So if life can only get started
around these rare,
548
00:31:22,230 --> 00:31:24,060
medium-sized stars,
549
00:31:24,070 --> 00:31:26,330
the chances
are not looking good.
550
00:31:31,470 --> 00:31:34,740
But life may have an ace
up its sleeve.
551
00:31:34,740 --> 00:31:40,110
What if life can start on
just one planet and then spread?
552
00:31:40,120 --> 00:31:43,320
What if life travels
across the cosmos
553
00:31:43,320 --> 00:31:47,320
looking for planets to conquer?
554
00:32:00,240 --> 00:32:03,100
Earth is
our only example of life
555
00:32:03,100 --> 00:32:06,440
emerging anywhere
in the universe.
556
00:32:06,440 --> 00:32:11,340
But what if life on Earth
didn't start on Earth at all?
557
00:32:11,350 --> 00:32:12,880
There's one idea that life
on Earth
558
00:32:12,880 --> 00:32:16,120
actually didn't get going here
but was delivered from space.
559
00:32:16,120 --> 00:32:19,120
Scientists
call this theory panspermia.
560
00:32:21,320 --> 00:32:23,560
The idea of panspermia
essentially talks
561
00:32:23,560 --> 00:32:28,490
about the transferral of life
throughout the cosmos.
562
00:32:28,500 --> 00:32:31,500
We know asteroids and comets
563
00:32:31,500 --> 00:32:33,600
carry organic molecules.
564
00:32:33,600 --> 00:32:36,340
But could they carry
life itself?
565
00:32:36,340 --> 00:32:38,470
What if life starts
on one planet?
566
00:32:38,470 --> 00:32:43,010
Can it actually get itself
to a nearby planet?
567
00:32:43,010 --> 00:32:44,410
Is it possible that meteorites
568
00:32:44,410 --> 00:32:48,480
could actually transport
living beings?
569
00:32:48,480 --> 00:32:51,850
For life to travel
around the cosmos,
570
00:32:51,850 --> 00:32:55,190
first, it needs to take flight.
571
00:32:55,190 --> 00:33:00,090
An asteroids is on a collision
course with an inhabited planet.
572
00:33:00,100 --> 00:33:02,800
So what happens if there's
a huge cataclysmic
573
00:33:02,800 --> 00:33:04,100
collision on a planet?
574
00:33:04,100 --> 00:33:06,730
Material is blasted off
into space.
575
00:33:10,810 --> 00:33:12,740
The impact might kill life
576
00:33:12,740 --> 00:33:14,270
on the surface of that planet,
577
00:33:14,280 --> 00:33:19,310
but it's possible
some bacteria might escape,
578
00:33:19,310 --> 00:33:24,250
hitching a ride on chunks
of the planet's surface.
579
00:33:24,250 --> 00:33:26,450
A meteorite being ejected
from a planet
580
00:33:26,450 --> 00:33:27,890
after an asteroids impact...
581
00:33:27,890 --> 00:33:29,820
I mean, that's not going
to be an easy ride.
582
00:33:29,820 --> 00:33:32,760
But it turns out
it's not as bad as you think.
583
00:33:32,760 --> 00:33:35,700
Some bacteria are
very, very hard to kill.
584
00:33:35,700 --> 00:33:37,860
Some we don't even know
how to kill.
585
00:33:37,870 --> 00:33:41,100
Even the impact that actually
threw that rock into space...
586
00:33:41,100 --> 00:33:42,900
The bacteria, no problem.
587
00:33:42,900 --> 00:33:46,870
If those chunks of rock expelled
during asteroids collisions
588
00:33:46,880 --> 00:33:50,380
could actually hold onto
viable organisms,
589
00:33:50,380 --> 00:33:52,510
then it really could change
the way
590
00:33:52,510 --> 00:33:58,250
in which we think about life
spreading in the universe.
591
00:33:58,250 --> 00:34:01,090
If the microbes
can survive takeoff,
592
00:34:01,090 --> 00:34:03,860
then they can start
their journey to a new home.
593
00:34:03,860 --> 00:34:06,690
The odds of life
conquering the universe
594
00:34:06,690 --> 00:34:08,160
seem to be getting better.
595
00:34:08,160 --> 00:34:11,500
The important question now is,
how long could that life,
596
00:34:11,500 --> 00:34:13,370
those bacteria,
those microorganisms
597
00:34:13,370 --> 00:34:16,700
inside that rock,
survive the space environment?
598
00:34:18,340 --> 00:34:21,310
Exposure to
u.V. Radiation could be fatal,
599
00:34:21,310 --> 00:34:25,110
killing any life on the surface
of an asteroid.
600
00:34:25,110 --> 00:34:27,850
But experts think
that microbial passengers
601
00:34:27,850 --> 00:34:32,190
could still survive
by hiding underground.
602
00:34:32,190 --> 00:34:36,390
It doesn't take much to shield
a microorganism from u.V.
603
00:34:36,390 --> 00:34:39,590
Just a little bit of rock,
and you have enough protection
604
00:34:39,590 --> 00:34:43,400
to just hold on throughout
a journey to the next body,
605
00:34:43,400 --> 00:34:45,870
to your next home.
606
00:34:45,870 --> 00:34:49,640
Eventually, they could
arrive at an uninhabited world
607
00:34:49,640 --> 00:34:52,170
that's ready and waiting
for life,
608
00:34:52,170 --> 00:34:54,670
but they're in for
a bumpy landing.
609
00:34:54,680 --> 00:34:58,610
Would the rock burn up coming
through a planet's atmosphere?
610
00:34:58,610 --> 00:35:02,120
It's in for a hot ride
but only for a few seconds,
611
00:35:02,120 --> 00:35:05,350
and only the outer layers
of that rock will blow off,
612
00:35:05,350 --> 00:35:08,150
and then it just falls and hits
the ground not that fast,
613
00:35:08,160 --> 00:35:11,190
a couple hundred miles an hour.
614
00:35:11,190 --> 00:35:13,090
If a human were in there,
that would be bad.
615
00:35:13,090 --> 00:35:15,900
But for bacteria, no big deal.
616
00:35:15,900 --> 00:35:18,560
The panspermia theory says
617
00:35:18,570 --> 00:35:21,170
life could start on
just one planet,
618
00:35:21,170 --> 00:35:26,110
then spread to another planet,
and possibly another.
619
00:35:26,110 --> 00:35:30,580
If we found alien life-forms,
would they look familiar?
620
00:35:30,580 --> 00:35:32,810
One of the biggest questions
about finding other life
621
00:35:32,810 --> 00:35:36,950
in the solar system is,
how similar will it be to us?
622
00:35:36,950 --> 00:35:39,850
If it's just like us,
it begs the question,
623
00:35:39,850 --> 00:35:41,790
did we have a common genesis?
624
00:35:41,790 --> 00:35:45,690
Did we originally
come from another planet?
625
00:35:45,690 --> 00:35:48,290
One radical idea
626
00:35:48,300 --> 00:35:52,170
is that life on Earth
came from mars.
627
00:35:52,170 --> 00:35:55,700
Imagine mars
3 1/4, 4 billion years ago.
628
00:35:55,700 --> 00:35:58,970
It was more earthlike then
than Earth was at that point.
629
00:35:58,970 --> 00:36:00,810
The Earth was still quite warm.
630
00:36:00,810 --> 00:36:02,840
Mars actually had cooled
off faster,
631
00:36:02,840 --> 00:36:04,580
had a thick atmosphere, water.
632
00:36:04,580 --> 00:36:07,010
Life could've arisen there.
633
00:36:07,020 --> 00:36:10,880
Mars has been
hit repeatedly by meteors,
634
00:36:10,890 --> 00:36:15,050
sending chunks of the planet
flying off into space,
635
00:36:15,060 --> 00:36:19,890
and some of those chunks
have landed here, on Earth.
636
00:36:19,890 --> 00:36:23,260
So this is
a really unusual meteorite.
637
00:36:23,260 --> 00:36:26,730
It was found near
the city of Los Angeles,
638
00:36:26,730 --> 00:36:29,270
and we actually know
639
00:36:29,270 --> 00:36:32,410
that it actually came from
the planet mars,
640
00:36:32,410 --> 00:36:35,440
and we know that because it has
gases trapped inside it
641
00:36:35,440 --> 00:36:38,040
that have the exact same
composition
642
00:36:38,050 --> 00:36:39,410
as the martian atmosphere.
643
00:36:39,410 --> 00:36:40,780
There's been a lot of transit
644
00:36:40,780 --> 00:36:43,480
between meteor strikes
hitting mars and then Earth.
645
00:36:43,480 --> 00:36:45,050
There's a little bit of mars
on Earth.
646
00:36:45,050 --> 00:36:47,390
There's a little bit
of Earth on mars.
647
00:36:47,390 --> 00:36:51,320
It's possible that life
started on mars
648
00:36:51,330 --> 00:36:56,930
and was transferred to Earth
inside of a meteorite.
649
00:36:56,930 --> 00:36:59,770
When you think about it,
maybe we're the immigrants.
650
00:36:59,770 --> 00:37:01,300
We are the martians.
651
00:37:01,300 --> 00:37:05,440
Life on Earth started on mars
and got transferred here.
652
00:37:09,380 --> 00:37:11,480
Panspermia could allow life
653
00:37:11,480 --> 00:37:13,480
to spread from planet to planet,
654
00:37:13,480 --> 00:37:15,550
conquering our solar system,
655
00:37:15,550 --> 00:37:19,890
but what about
even greater distances?
656
00:37:19,890 --> 00:37:24,290
In 2017, the cigar-shaped
space rock 'Oumuamua
657
00:37:24,290 --> 00:37:26,260
appeared in our solar system.
658
00:37:26,260 --> 00:37:28,490
It came from interstellar space,
659
00:37:28,500 --> 00:37:32,570
and experts think it could be
carrying organic matter.
660
00:37:32,570 --> 00:37:34,670
One of the fascinating
things about 'Oumuamua
661
00:37:34,670 --> 00:37:36,870
is it has sort of
a reddened surface.
662
00:37:36,870 --> 00:37:38,140
Now that could actually
partially be
663
00:37:38,140 --> 00:37:40,470
from the presence
of organic molecules.
664
00:37:40,480 --> 00:37:42,640
Could life survive
665
00:37:42,640 --> 00:37:45,980
interstellar
or even intergalactic travel?
666
00:37:45,980 --> 00:37:49,780
Whether or not this is an easy
way to transfer life around
667
00:37:49,780 --> 00:37:52,650
in the universe,
it's still an open question.
668
00:37:52,650 --> 00:37:55,420
The possibility of transferring
life from star system
669
00:37:55,420 --> 00:37:59,030
to star system
seems a little bit remote.
670
00:37:59,030 --> 00:38:00,690
The immense distances
671
00:38:00,700 --> 00:38:02,500
and dangers
of interstellar travel
672
00:38:02,500 --> 00:38:04,460
would be hard to survive.
673
00:38:04,470 --> 00:38:08,270
Some experts think there is
one way for life
674
00:38:08,270 --> 00:38:11,840
to conquer the universe,
675
00:38:11,840 --> 00:38:15,010
but it won't be life
as we know it.
676
00:38:26,890 --> 00:38:31,060
The universe is
unimaginably large.
677
00:38:31,060 --> 00:38:35,130
Many experts believe
there is life out there.
678
00:38:35,130 --> 00:38:37,360
We just have to go find it.
679
00:38:37,370 --> 00:38:40,630
One of the things
I love about being a human
680
00:38:40,640 --> 00:38:44,640
is the fact that
I'm born with this curiosity.
681
00:38:44,640 --> 00:38:46,510
This curiosity drives us to
explore... explore Earth,
682
00:38:46,510 --> 00:38:50,080
explore our solar system
and beyond into the galaxy,
683
00:38:50,080 --> 00:38:52,910
look for other life-forms.
684
00:38:52,910 --> 00:38:55,110
But with current technology,
685
00:38:55,120 --> 00:38:59,390
it would take thousands of years
just to reach the nearest star.
686
00:38:59,390 --> 00:39:03,120
It's unlikely humans
will ever leave our galaxy.
687
00:39:05,660 --> 00:39:10,130
If life one day does spread
from Earth into the cosmos,
688
00:39:10,130 --> 00:39:12,570
it's probably not just going to
be a bunch of meat bags,
689
00:39:12,570 --> 00:39:16,970
like us, but other forms of life
that are more suited
690
00:39:16,970 --> 00:39:21,210
for interstellar
and intergalactic travel.
691
00:39:21,210 --> 00:39:24,040
Our fragile bodies are
not suited to the distances
692
00:39:24,050 --> 00:39:28,580
and dangers
of interstellar travel.
693
00:39:28,580 --> 00:39:33,190
Machine life may be more robust
for traveling between planets
694
00:39:33,190 --> 00:39:36,420
and between stars
than biological life.
695
00:39:38,690 --> 00:39:40,260
There are a lot of scientists
that think
696
00:39:40,260 --> 00:39:43,630
when we encounter aliens,
we won't be encountering them.
697
00:39:43,630 --> 00:39:45,230
We'll be encountering
their machines
698
00:39:45,230 --> 00:39:48,170
because we can build machines
that can last a million years,
699
00:39:48,170 --> 00:39:49,600
go from one star to the next.
700
00:39:49,600 --> 00:39:51,570
It's much easier
than transporting us,
701
00:39:51,570 --> 00:39:55,410
fragile gloppy bags of meat.
And so if we go out into space,
702
00:39:55,410 --> 00:40:00,910
we're more likely to find robots
than we are biological life.
703
00:40:00,920 --> 00:40:03,780
For humanity to
discover alien life,
704
00:40:03,790 --> 00:40:08,250
humanity itself may have
to evolve
705
00:40:08,260 --> 00:40:13,530
from biological life
to artificial life.
706
00:40:13,530 --> 00:40:16,030
What's really ironic
here is that
707
00:40:16,030 --> 00:40:19,970
while we're figuring out
the origin of life on Earth,
708
00:40:19,970 --> 00:40:23,600
we humans could be inventing
a form of life on our own,
709
00:40:23,600 --> 00:40:27,110
and that is what we call
artificial intelligence.
710
00:40:27,110 --> 00:40:31,680
The development of A.I.,
self-replicating machines even,
711
00:40:31,680 --> 00:40:34,650
may very well be
just the next key transition
712
00:40:34,650 --> 00:40:37,050
in our evolutionary history.
713
00:40:39,890 --> 00:40:43,560
Could a superintelligent
self-replicating machine
714
00:40:43,560 --> 00:40:46,960
conquer the universe?
715
00:40:46,960 --> 00:40:51,830
Maybe this A.I. can fashion
its own machines,
716
00:40:51,830 --> 00:40:55,300
create factories to create
resources to replicate itself,
717
00:40:55,300 --> 00:40:58,740
create ships
that will allow it travel
718
00:40:58,740 --> 00:41:01,040
from one place
in the universe to another.
719
00:41:03,880 --> 00:41:07,810
But would A.I.
Represent a new form of life?
720
00:41:07,820 --> 00:41:09,150
I think the answer is yes.
721
00:41:09,150 --> 00:41:11,080
I think it actually goes on
from there.
722
00:41:11,090 --> 00:41:12,990
I think artificial intelligence
might be
723
00:41:12,990 --> 00:41:15,690
the next necessary stage
in evolution.
724
00:41:15,690 --> 00:41:19,230
We made the computers.
They are our children.
725
00:41:19,230 --> 00:41:24,400
I think of life as a process
that can retain its complexity
726
00:41:24,400 --> 00:41:29,370
and reproduce,
so bacteria are life.
727
00:41:29,370 --> 00:41:33,370
Humans are life,
and some future creation
728
00:41:33,370 --> 00:41:34,940
of advanced
artificial intelligence
729
00:41:34,940 --> 00:41:38,680
that can do those things
should also count as life.
730
00:41:41,620 --> 00:41:44,280
Life could take many forms,
731
00:41:44,290 --> 00:41:47,620
and in such a vast universe,
732
00:41:47,620 --> 00:41:52,630
it could be that life
is inevitable.
733
00:41:52,630 --> 00:41:55,060
With all those stars
and all those planets,
734
00:41:55,060 --> 00:41:58,160
I think, without a doubt,
there is a good chance
735
00:41:58,170 --> 00:42:02,300
that life has developed
elsewhere in our universe.
736
00:42:02,300 --> 00:42:05,440
Must life happen
in our universe?
737
00:42:05,440 --> 00:42:10,680
Is it an inevitable consequence
of processes in operation?
738
00:42:10,680 --> 00:42:13,310
Maybe, maybe not.
739
00:42:16,680 --> 00:42:21,550
Until we find it,
we won't know for sure
740
00:42:21,560 --> 00:42:25,420
whether life can conquer
the universe.
741
00:42:25,470 --> 00:42:30,020
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