Original subtitles

(dramatic music)

This is a vision of our future,

the fateful day in a far-flung corner of our universe

when a probe from Earth initiates the first descent

onto an alien world.

(dramatic music)

Looking for proof of life beyond our solar system.

There are no witnesses, no cheering crowds

in a control room.

A decade or more will pass before news finally reaches us

back across the dark oceans of space.

But the seeds of this mission are already being sown today,

by the first generation of scientists bold enough

to believe it could be possible.

When I look up in the sky, and I see not stars,

I see planetary systems.

We must understand that journey

to exoplanets is not limited by the laws of physics.

They look to planets orbiting distant stars,

searching for an answer to the oldest human question.

Are we alone?

Is there life on other worlds, and if not, why not,

and if so, how?

This is the first generation in human history

where we have the technological ability

to actually go and answer that great question.

This is the story of humanity,

launched into the final frontier

by a new breed of adventurers.

The planet hunters, engineers, explorers and dreamers,

taking the first steps on an interstellar journey

they know that they will not complete,

a journey beyond the human mind,

in search of consciousness among the stars.

I want to see what's next.

I want to know whether or not, in my lifetime,

my children's lifetime, or their children's lifetime,

we will come face to face with unambiguous evidence

that there's intelligence somewhere else.

(dramatic music)

(electronic whooshing and beeping)

I am the mind of the mothership,

alone among the stars.

50 years ago, from a planet far away,

the planet you call home, I launched.

(jets flaming)

(beeping)

A journey of 28 trillion miles across the yawning time

of space to the exoplanet, Minerva B:

a small, rocky planet, much like Earth,

but orbiting another sun.

Here, I have found water, organic molecules,

and microorganisms.

I have found life.

(dramatic music)

When the news of my discovery reaches Earth years from now,

some of you will be amazed.

But others will remain unsatisfied,

and you will ask, have I not found animals or birds?

Have I not met intelligent life like us?

And so, my search continues.

(birds chirping)

(hopeful music)

The great marvel and the paradox

of wide open spaces is that they make us look inwards.

Confronted with the infinite,

we reflect upon the self.

Where do we come from?

Why are we here?

Are we alone?

(hopeful music)

As a young child, I was mostly interested in philosophy

and I used to wander into the hills of the village

where I was born.

I was interested in questions about our existence,

involving also the big picture,

which us being in the universe.

The question is how did we come to be

inhabiting this two dimensional surface

on a piece of rock we call our home, the Earth,

near a star like the sun that is one

out of tens of billions of stars in the Milky Way galaxy,

that is one out of trillions of galaxies in the universe.

How did this all come about,

and are we alone, in particular?

Professor Avi Loeb grew up,

but he never grew out of his obsession

with the fundamental mysteries of life.

(hopeful music)

Today, as chair of astronomy at Harvard University,

Loeb is part of a generation of elite scientists,

riding a revolution, in the quest to understand

our place in the universe.

We are living at a very special time.

Over the past two decades, thousands of planets

were discovered around other stars,

and we realize that our solar system is not rare.

There are planets around almost every star,

and moreover, about a quarter of all stars

have an Earth mass planet orbiting

just at the right distance for liquid water

to exist on its surface,

and for the chemistry of life to develop.

The odds of finding life among the stars

have never been better.

(hopeful music)

Following the detection in 2016 of organic molecules

on the moons of Saturn, on the comet 67P,

and in the disc of an emerging star system,

scientists now believe that the building blocks

for simple life are common throughout the universe.

In my view, it is very likely that life,

primitive life exists on many other planets.

The question of whether intelligent life exists

is more difficult to answer,

because we don't fully understand what led to our existence

and moreover, intelligent life existed on Earth

just relatively recently, in cosmological terms.

But I'm agnostic about whether the answer is yes or no.

I think we should explore, rather than have a prejudice.

Just like Columbus went out to discover the new world,

the answer lies in space.

(upbeat music)

(electronic whooshing and beeping)

I am in a stable orbit around the exoplanet

Minerva B.

My solar panels are configured to harness

the full spectrum of its muted red dwarf sun.

I keep a watchful eye over my swarm

of explorer robots below.

I scan the radio, and optical wavelengths,

hoping for a whisper of alien technology.

But Minerva B is silent.

(upbeat music)

What would it take to calculate the odds

of finding intelligent life among the stars?

In the early 1960s,

one audacious astronomer, Frank Drake,

devised an equation to answer that question.

The Drake equation, essentially,

is a statement of our ignorance about life in the universe.

In the first meeting held in the United States

about the search for extraterrestrial intelligence,

Frank Drake and a number of other researchers got together,

and Drake needed a way to organize how the discussion

of the meeting would go,

and he sat down and thought, well, what do I need

to know, in order to know how many intelligent civilizations

there might be out there in the galaxy

for us to communicate with?

(dramatic music)

Drake listed seven variables he believed

would need to be worked out in order to determine

the number of intelligent civilizations in our galaxy.

With six of those seven variables unknown at the time,

Drake did not foresee a ready solution.

But according computational astrophysicist, Adam Frank,

that's all changing.

We are, in fact, going through quite a bit of a revolution

in this idea, in this equation.

In particular, what it comes from is the fact

that we have nailed two of the terms.

So in 1962, when Drake wrote down this equation,

only one of the terms was know.

R stands for the rate of star formation,

or the number of sun mass stars born each year.

In 1962, Drake put the figure at 10.

But it wasn't until 2011 that NASA's Kepler space telescope

gave us the answers to the second and third variables

in Drake's equation, the fraction of stars that have planets

and the number of those planets with the right conditions

for life to form.

It turns out that the fraction of stars with planets

is approximately one.

Every star you see in the sky,

when you walk out at night,

and look at a random star in the sky,

it has a planet, at least one.

And then then the number of planets in the habitable zone

turns out to be on he order of 0.2.

So this is like saying if you look at

between four and five stars,

one of those is going to have a planet

in the right place for life to form.

Remember that the galaxy contains 400 billion stars,

just the galaxy alone.

400 billion stars.

So when you think about all those stars in the galaxy,

that's an amazing number.

Up to 80 billion exoplanets in our galaxy

have the right conditions for life.

When you consider that at the time

Drake formulated his equation,

no one knew if there was even one exoplanet out there,

this truly is a revolution of our understanding.

But what about the other unknowns in the Drake equation?

Inspired by Kepler's game changing discoveries,

a new generation of scientists has made it their mission

to fill in the blanks.

(upbeat music)

Of all the habitable exoplanets out there,

how many of them actually host life?

This is the next unknown in the Drake equation,

and the challenge it presents for scientists is immense.

How does one detect life from light years away?

(birds chirping)

One approach that shows promise

is to study the gases around exoplanets,

in search of a so-called biosignature,

the evidence of life imprinted in the atmosphere.

I think one of the things that's most exciting

for exoplanet atmospheres right now

is that we can actually measure gases

with telescopes from Earth.

Remote sensing is a very powerful technique.

It's how we first studied the solar system.

Planetary scientist Sarah Horst

is a leading investigator of atmospheric chemistry,

a field that took off in a radical, new direction in 2001,

with the first ever detection of an exoplanet's atmosphere.

(dramatic music)

There's a very small number of gases

that we're pretty sure we've been able to see

in exoplanet atmospheres.

So water is one of the gases that people claim

that they've detected.

Some other things that you don't tend to think of as gases

has also been detected: things like sodium, for example.

The main challenge with exoplanets

is just that they're very far away,

and so you need a bigger telescope.

That telescope is soon to be launched.

(hopeful music)

While atmospheric observations so far have limited

to a narrow range of gases,

the James Webb space telescope will be the first instrument

capable of sampling a broad spectrum.

The challenge now for researchers like Horst

is to define a set of biosignatures,

gases that indicate the presence of life,

for the James Webb to go looking for.

One of the gases on Earth that is most significant,

in terms of the fact that there's life on Earth is oxygen.

The oxygen on Earth is produced by life.

That's why it's here,

but oxygen isn't necessarily a biosignature.

If you saw oxygen around another world,

you wouldn't necessary say, "Oh, that's life."

Europa's main atmospheric constituent is O2,

and it's not from life.

It's from breaking up water,

so it's difficult to point to when gas,

or even a small set of gases that you would say,

"If I see that, I know there's life there."

That said, solar system exploration tells us

that we will always be surprised and so it's quite possible

that there is going to a planet where we get the data

from James Webb, and it is going to be glaringly obvious

from the data that there's life on that planet.

Horst's generation may well be the first

to put a number on the fraction

of habitable exoplanets that host life,

but the next unknown in the Drake equation

could prove much more challenging to resolve.

How many of those life bearing planets

go on to develop intelligence?

Even if we understand that other planets

have simple life on them, and indeed,

we might be able to make astronomical observations,

or test that, over the next 10 or 20 years,

then, of course, there's another big uncertainty,

which is how likely it is that simple life

evolves as it did on Earth, into a marvelous,

complex biosphere containing even creatures like ourselves.

We don't know what the chances are of getting

from simple life to advanced life

of the kind that we recognize as intelligence.

(dramatic music)

(whooshing)

After 47 days of exploration,

I have found no trace of extant animal life,

and so I search into the past.

(dramatic music)

I scan the strata of an exposed deformation

for fossil evidence.

(upbeat music)

I uplink the data to my orbiter for analysis.

(upbeat music)

(whooshing)

(electronic beeping)

There's something here.

(fast electronic beeping)

Reptilian, approximately one million years old.

Terrestrial compatibility detected,

an (mumbling) Komodo-like species.

(dramatic music)

(electronic beeping)

Marine compatibility also found,

a possibly transitional species from sea to land.

Did complex life fail to establish itself

on the surface of Minerva B?

Or is this evidence of extinction?

(upbeat music)

To solve the next unknown

in the Drake equation,

the fraction of worlds where simple life

evolves to intelligence,

we need to understand the evolutionary pathway

to advanced life on Earth.

Just over 540 million years ago,

evolution on our planet took a giant leap forward.

There's no better place to understand that process

than here, in the Canadian Rockies,

in the rich fossil deposits of the Burgess Shale.

For well over a century,

the fossils hidden in these mountains

have helped generations of scientists retrace

the evolutionary pathway to complex life on Earth.

Professor Robert Gaines and Dr. Jean-Bernard Caron

are leading the excavation of a recently identified deposit

in Marble Canyon.

Battling the icy wind and snow,

for the prospect of a new discovery.

I have something to show you here

that we collected the other day.

It's a big slab.

Wow.

Baseball saw here. Wow.

Yeah, it's quite extraordinary, isn't it?

I've never seen anything like that.

That's the exciting part of our profession.

There's always something new coming up.

Yeah.

These rocks contain some of the first evidence

of multicellular organisms on our planet.

The first eyes, the first hard body parts,

bones and exoskeletons,

the first lateral symmetry,

the first efficient guts,

even the first brains,

sculpted in the finely packed sediment of an ancient ocean

is the turning point in the evolution

of advanced life on Earth, the Cambrian explosion.

What you got?

I don't know.

A very nice slab with some (mumbling) on it.

Oh, wow.

Wow, that's quite spectacular.

So to put things into perspective,

today, we know life is widespread.

It's all around us, in the oceans,

in the mountains, and so on and so forth,

and we can trace the root of all these life forms

to pretty much the Cambrian period.

(tools whirring)

As far as we know, life dates back at least

to 3.4 billion years ago,

and it wasn't until about 540 million years ago

that we had the Cambrian explosion,

and that fundamentally changes the planet.

It goes from a microbial world

to one that is literally teeming with animals

and not just small and simple animals,

as we would've originally imagined,

but instead, we have a whole array of complex life,

still only in Earth's oceans, at that time,

but all of the major groups of animals appear

geologically instantaneously.

(upbeat music)

Among the species found here

is one of the ancestral roots

on the tree of intelligent life.

So one of the most important fossils

that we find here in this area is Metaspriggina.

It's hard to pronounce,

but it's actually a very, very important fossil

for the understanding of our own group, the vertebrates,

and this is an animal that looks like a fish.

It has a pair of eyes in the front,

and a structure which we call a notochord,

which apparently will eventually become our spine,

and Metaspriggina doesn't have any evidence

of structures that could help him to protect itself,

so I tend to think perhaps he was smart,

and the fact that we find them clustering,

which shows evidence of schooling,

is very much reminiscent to what we know in modern fish,

who have evolved such behavior to avoid predation.

Predation is a very key factor

in driving the evolution of animals,

and we see evidence of that here in the Burgess Shale,

as organisms began to develop both weaponry,

to capture one another, as well as defenses.

(dramatic music)

Eyes, claws, camouflage, armor.

All these new tools required coordination

by a nervous system, the stuff from which the brain is made.

So could intelligence be the product

of an evolutionary arms race?

We certainly see on Earth a connection

between predation and mobility.

Organisms that can just sit in the sun,

and soak up the rays, they don't need to move.

Their food comes to them,

but organisms that prey on vegetation

need to be able to move around,

and organisms that prey on the preyers

need to move even faster,

and they need to be really strong and fast,

and you could argue that that dynamic

of predation and motion

causes the development of intelligence,

and maybe somehow, it leads to the sort

of overwhelming intelligence that humans have expressed.

Is this the inevitable

progression of evolution?

From simple life via diversification

and predation into intelligence,

or is an event like the Cambrian explosion so rare

that life on other planets

might never get the chance to pass first base?

(dramatic music)

I think that wherever

we find life in the universe,

that life will change through time in a way

that's consistent with what we've learned

about evolution on this planet.

I think that is a general feature of life.

To Professor Andy Knoll,

similar environmental conditions or biomes

will give rise to similar evolutionary solutions,

no matter where in the universe that takes place.

It's a theory known as convergence.

If you look at a bat, for example,

and a bird, they both fly using wings,

and yet, they don't have a common ancestor

that flew and had wings.

They have evolved that capacity from separate origins,

but to a similar functional end.

In advanced animal life,

some convergent biological structure are so common

as to be almost universal.

Well, the eye is a terrific example of convergence,

because we all understand what the eye does.

Your eyes are this sophisticated sensory apparatus

that allows you to gauge

and engage with the world around you.

Interestingly, if you look at squids and octopus,

they have a visual system that is ever bit as acute as ours,

but evolved from a separate source.

Again, there's no common ancestor of squids

and mammals that had an eye.

(owls howling)

Is convergence a magic funnel

that guides life on any planet,

inexorably towards intelligence?

Or could there be other, more powerful forces at play?

(suspenseful music)

(electronic beeping)

The absence of terrestrial animals

on Minerva B could indicate an extinction event,

or that life has not successfully transitioned

as it did on Earth, from sea to land.

(water splashing)

I deploy my submarine explorer module into the Minervan sea.

In the shelter of the ocean, life should thrive.

(whirring)

Extensive macroalgae and porifera

suggest high water oxygenation and shallow UV penetration,

ideal conditions for advanced life to evolve.

(upbeat music)

A giant trilobite-like species,

tagmata body plan and dorsal exoskeleton,

comparable with late Cambrian arthropods on Earth,

complex mobility and behavior,

a school swimming in formation,

(upbeat music)

perhaps a strategy to avoid predation,

strength in numbers, or a kind of camouflage.

(suspenseful music)

(crunching)

(dramatic music)

(upbeat music)

(water rushing)

The fourth variable in the Drake equation,

the fraction of life bearing worlds that evolve intelligence

still eludes scientists today.

On Earth, the great burst of life

during the Cambrian explosion was an integral step

on the path to intelligence.

But could widespread death have been just as important?

You know, Einstein said,

"God doesn't play dice with the universe."

Well, it seems that He does,

and there's a whole lotta dice going on

in the evolution of life.

Paleontologist Peter Ward

is an expert of mass extinctions,

the catastrophic changes of fortune in the game of life.

When the majority of animals lose,

and just a few inherit the Earth.

This is a mammal-like reptile,

actually called a Gorgonopsian or a Gorgon.

It was the biggest and baddest carnivore

of the late Permian, 252 million years ago,

and this is a baby.

The big ones were three meters to four meters long,

very large skulls, a cross between a lion

and a big, saltwater crocodile, if you will,

half reptilian, half mammal, all nightmare.

These guys all died out in the Permian extinction,

252 millions year ago.

Its entire group, gone.

The Permian extinction was the most devastating

of the five mass extinction events in Earth's history.

(dramatic music)

Experts believe an intense surge of volcanic activity

led to dropping sea levels, acid rain,

and poisoning of the atmosphere.

More than 95% of marine life,

and over two thirds of terrestrial animals

were completely wiped out,

resetting the stage for the evolution of life on our planet.

The Permian extinction did far more

than just the top carnivore.

It took out the herbivores, it took out most of the plants.

It took out the insects, the amphibians,

but what did get through were a couple small,

reptilian groups, real small in size.

Like pruning a rose,

cutting back the tree of life gives rise to rapid growth,

as new branches reach out their leaves to the light.

With little competition or threat from predators,

surviving species adapt quickly

to fill the gaps left behind.

The tiny reptiles that survive the Permian extinction

grew into hundreds of different species,

including dinosaurs who ruled the Earth

for over 100 million years,

until their own date with disaster arrived.

(explosion)

(ethereal music)

I mean, that was a very rapid and hideous death,

probably every dinosaur dead within three to six months max.

That was a line in the sand.

Who wins?

Well, who won are the small creatures.

The T-rexes die out, and tiny mammals get through,

and then they develop into all the kinds of mammals

we see today, and they did so really fast.

The size of the skull of the animal that gave rise to us

was the size of a robin egg or smaller.

(dramatic music)

(screeching)

Might the evolutionary branch that led to us

never have grown had it not been for the random impact

of an asteroid 65 million years ago?

(suspenseful music)

I would support the idea that in fact,

if we still had not had the impact,

something else might be running around as intelligent,

but I doubt it would be in this form,

and this set of behaviors that we humans have.

If our own existence is the outcome

of a random, cosmic disaster,

then might the fraction of worlds that evolve intelligence

be equally unpredictable?

(dramatic music)

But if we could go looking for alien intelligence

on another planet, how would we recognize it?

(ethereal music)

I think a method of looking for complex behavior

on a different planet is to do

what behavioral scientists do.

You look, you observe, you see how animals move,

how they respond to stimuli, how they act.

As a biologist who does this regularly,

I find that extremely exciting,

because the discovery quotient would be very high,

but it would also be weird and alien.

I sorta like weird and alien,

so I think that would be a lot of fun.

(ethereal music)

Professor Roger Hanlon is an expert on the closest thing

to alien intelligence on Earth: cephalopods.

Squid, octopus, and cuttlefish,

the undisputed masters of disguise,

because they have to be.

(hopeful music)

Cephalopods are soft bodied.

All their armor was given away, through evolutionary time,

to their cousins, the oysters and the clams,

and they are soft bodied.

They're extremely vulnerable,

so they have to get on by their wits.

They have to do something different.

(dramatic music)

They're making that decision, in far less than one second,

in about one third of one second,

they're assessing that visual scene.

Now they're orchestrating in their skin

30 million chromatophore pigment organs in the skin,

that create the pattern and iridescent reflective cells,

and even the skin papillae and the bumps,

there are several thousand of those,

so that takes a lot of cognitive processing,

a lot of brainpower.

Cephalopods have the highest brain

to body mass ratio of all invertebrates,

and their brains are decentralized,

meaning neural tissue is distributed throughout their body.

Having split from our own group, vertebrates,

well before the Cambrian explosion,

they are the product of an entirely separate experiment

in the evolution of intelligence.

If you look at the evolutionary history of complex behavior,

we know about vertebrates and humans and primates

and all the rest, but through evolutionary time,

there's only group that has branched off

to produce really complex behavior, and it's these animals,

the squid, octopus and cuttlefish.

So what we expect is for the white square to show up

in the white headbar.

The white headbar is already there.

And now it's changing its pattern a little more,

it's blanched a little bit.

You can see these two markings down here,

but we're looking for that white square to appear.

I think the correlation you might make

for looking for extraterrestrial intelligence

would be don't expect anything like humans

or dogs and cats and all the things we're used to.

Here underwater, you have this weird octopus

with its head on its feet, and distributed brain,

but they're doing complex things.

We might find something very similar in a different planet.

It might be a different size, a different shape,

and its form of intelligence may be different, as well.

So I think we have to open our minds

and recognize the diversity on this planet to set the stage

and the framework for going to other planets

to look for life forms and intelligence.

(dramatic music)

(electronic skittering)

(electronic beeping)

Night falls on Minerva B,

and a secret world is revealed.

Bioluminescent organisms rise from the Earth.

(electronic skittering and whirring)

Winged insects, resembling lampyridae.

Complex life exists on land, but hidden from the sun.

(dramatic music)

A predator breaks its camouflage,

and reveals a nocturnal hunting ground.

(dramatic music)

(electronic whirring)

(chomping)

(dramatic music)

(bird chirping)

Since the 1960s,

when Frank Drake drafted his equation,

the search for extraterrestrial intelligence

has been defined in terms of the search

for a technological civilization.

Being unable to travel to the stars,

Drake's solution was to scan for signals

that our Earth-bound technology could detect,

hence the penultimate unknown in his equation,

the fraction of intelligent civilizations

that develops technology.

The key here is the ability for that civilization

to be detected by us,

and so that is really going to require

some kind of world girdling industrial civilization.

So if there was a Roman Empire on this distant planet,

we would really have a hard time seeing it,

but once they start generating,

or start deploying industrial scale technologies

on a global scale, then we think there's going to be ways

we would be able to see that.

(dramatic music)

The new technology when the Drake equation

was formulated was the radio telescope,

and those who search for extraterrestrial life today

still believe an alien radio signal

is what we're most likely to detect.

I think I get comments at every party I go to,

not that I go to a lot of parties,

but there are people who are saying,

"Oh, you're looking for radio waves from ET?

"I mean, that's pretty old school, isn't it?

"They won't be using radio."

Well, tell me what's better.

I mean, as far as we know,

there really isn't anything better,

because radio waves can traverse the distances

between the stars, so the signals can get here,

and radio goes right through the gas and dust

that hangs between those stars,

so you can send radio signals as far away as you want.

(sizzling)

(phone ringing)

SETI Institute, this is Seth.

Seth Shostak has spent his life

listening to the stars.

All right, both.

Okay, thank you, bye.

As senior astronomer at the Institute

for the Search for Extraterrestrial Intelligence, or SETI,

it's his job to scan the heavens for alien technology.

We try anything we can to pick up some information,

some sort of signal that would tell us,

we don't know what they're like

or what their taste in music, anything like that,

but what we do know is that they're smart enough

to build a radio transmitter, for example.

With limitations on technology,

time and resources, the dilemma for SETI

has always been where to listen.

We haven't heard anything.

I mean, let me be straight up about that,

and some people think, yeah,

the reason you haven't found anything

is because there's nothing to find.

We're the smartest things in the universe.

Well, I don't think it's true.

I think the reason that we haven't heard anything

is simply because we have only looked

at a very small number of star systems, but that's changing

because of the improvements in technology.

Instead of looking at a couple of hundred star systems

every year, we'll be able to look at a couple of thousand,

and then five years down the road,

it'll be tens of thousands,

and then the next two dozen years,

we'll be able to look at on the order

of a million star systems.

Now if you look at a million star systems,

the chances of finding something are not so small.

So I bet everybody a cup of coffee

we'll find ET within two dozen years.

I could be out a lotta coffee.

(upbeat music)

For almost 50 years,

since Drake wrote his equation,

we listened, but nothing we heard couldn't be explained

as interference or a natural phenomenon.

(upbeat music)

Until one day in 2007, in rural Australia,

astronomers picked up the first

in a series of mysterious signals

that still puzzle the science community today.

(upbeat music)

At first, we didn't dare believe that they were real.

Fortunately, I've seen them with my own eyes.

I saw the very first sweep of the first one.

Couldn't sleep that night.

I was like, could this possibly be real?

This is amazing.

And we've been able to work out how far away

they are in the universe,

and they're impossibly far away.

They're billions of light years away,

so the process that creates them is so energetic

that its great mystery is to what causes them?

The strange signals have been dubbed

fast radio bursts, blasts of radiation so powerful

they emit the energy of 500 million suns.

Professor Matthew Bailes leads an international effort

to study the phenomenon, here at the Molonglo Observatory.

[Professor Bailes] Fast radio bursts are these mysterious

bursts of radiation that only happen for a few milliseconds.

The sky lights up, and then they go away again.

They're about a million times more luminous

than anything we've known about in our own galaxy.

Since the first detection in 2007,

there have been more than 40 fast radio bursts

detected worldwide.

Five in just the last year were detected here by Bailes.

One of the holy grails is to find

a repeating fast radio burst,

and is there any pattern to the fast radio burst?

Do they come in special gaps, or are they regular?

If they are very regular, we might associate that

with a rotating neutron star,

where a sort of death ray is going past the Earth,

you know, once every 20 seconds or something.

If they come at irregular intervals,

or if they came separated by a code,

that showed us that there was

some higher intelligence behind it,

you might think there's an intelligent civilization,

that's actually transmitting this signal.

That would be Nobel Prize winning stuff.

Of course, the next question then is

could we or should we send a message back?

New clover leaf.

If we took our biggest radio telescope,

we could actually mimic

what a fast radio burst would look like,

and if we were trying to communicate

with other intelligent beings,

we might imagine that they go through a stage

of their evolution, where they're searching

for fast radio bursts in the same way I am here.

And then if you could find one that repeats,

and find a pattern, that might be a way

of doing intercivilization communications,

which is a fascinating thing.

(mechanical whirring)

What we're really interested in

is a civilization like ours,

an industrial civilization that shows signs

that in building tools of whatever kind,

they have gotten to the point where they clearly have

a kind of reasoning, rational intelligence,

a culture that we might be able to talk to them,

'cause that's really what we wanna know.

We wanna know what it's like to be them,

because all we know is what's it like to be us?

(dramatic music)

If I received a signal from outer space,

how could I tell it was a language,

as opposed to anything else?

To put a figure on the fraction

of civilizations that develops communication,

we need a way to decipher if an alien signal

is actually trying to tell us anything.

I analyzed over 60 different languages,

human languages, plus languages

like dolphin, chimp, the birdsong.

So on the left here, you've got Neil Armstrong

speaking from the moon.

It's one small step for man,

one giant leap for mankind.

On the right here,

you've got a dolphin communicating.

(dolphin pulsing)

And see here, quite easily,

the rhythms going on, the sounds that we're making,

how similar those constructs are.

It's picking up those rhythms

and those interrelationship pattern,

that I think are fundamental to any communication,

whether it's on this planet or in another planet,

and looking at the complexity

of how those planets interrelate,

you can actually tell how intelligent the author is.

(dramatic music)

When the signal arrives,

it's first checked against known sources of interference.

It's a pulsar.

(repetitive tapping)

That repetitive sound going on.

Listening to that, it's not real agreement.

That's too simple.

Algorithms then scan for the telltale patterns

of communication, whether its source may be

an audio recording or an intergalactic email.

It's an awfully big sky.

We're getting more and more capability online,

the hardware to do it, but I suspect,

unless we eavesdrop on something,

it may be awhile before we hear anything,

but we wanna be ready for it,

so there's no point just sitting back and saying,

well, do saying when it happens,

it's doing all this ahead time,

and so we prepared for it.

But again, it could happen tomorrow.

You just don't know.

(dramatic music)

Recent advances in the remote observation

of planetary atmospheres have opened up a new method

of determining whether an exoplanet hosts

or have previously hosted a technological civilization.

The composition of the atmosphere can provide us

with a hint about the intelligent, or perhaps,

not so intelligent life that pollutes the atmosphere,

with industrially produced molecules.

Pollutants, such as chlorofluorocarbons,

are released into Earth's atmosphere

by industrial processes and do not occur naturally.

Detecting them in an alien atmosphere

would therefore be a clear footprint of technological life.

(horn honking)

Some of these molecules exist

for tens of thousands of years,

after they were introducing to the atmosphere,

so in principle, we can find evidence for a civilization

that is no longer in existence

on the surface of that planet.

We can find graveyards of civilizations.

(ethereal music)

My drones have picked up a disturbance

in the communications field,

a sporadic interruption to the network.

(hopeful music)

Is this what caused it?

Some geometrical formation, metallic,

magnetically charged,

part of a larger configuration,

which seems to bear the mark of design.

(electronic whirring)

(upbeat music)

Could these be the ruins of a Minervan civilization,

the tombstone of an alien intelligence?

(electronic whirring)

(ethereal music)

(birds chirping)

The final factor in the Drake equation is L,

the average lifetime of a civilization,

and in some sense, this is the most difficult term

to even think about,

because we've got only one example,

and we don't even know what our own future is.

When Drake conceived his equation in 1962,

our own global civilization was on the brink of disaster,

as the powers of East and West faced off

in the Cuban Missile Crisis.

For a city--

The group that came up with the Drake equation,

that first workshop, for them, in 1962,

the great fear was nuclear war,

and at the end of the conference,

Otto Struve, who was the head of the observatory

where the conference was being held,

made a toast and said, "To L, may it be very long."

(dramatic music)

(crumbling)

The Cold War did eventually thaw,

but while the nuclear threat is diminished today,

we have created for ourselves new dangers.

(metallic creaking)

The question is how long are we gonna last?

Do we only have another 200 years before we collapse?

Do we have 200 million years in front of us,

so this is, you know, it's really a fundamental question,

and it's a fundamental question for human beings,

because right now, with climate change and sustainability,

we really face this existential crisis about really,

are we gonna be able to make it through

to more than another hundred or 200 years?

Oh, check this out.

Could this be the ultimate limiting factor

in the Drake equation,

that before technological civilizations work out

how to search for life among the stars,

they destroy themselves?

In order to become truly a space faring race,

that takes a lot of time,

to be able to really have settlements on Mars,

to really start to begin to have a human presence

in the solar system will take hundreds of years,

and if we can't make it more

than a couple of hundred of years,

clearly, we're not gonna develop that kind of society,

and then to ever really think about getting to the stars,

sending probes to the stars,

being around for the signals to come back,

you have to last a long time.

I think those two things are intimately connected,

and you don't get the stars unless you get the Earth.

(ethereal music)

(electronic beeping and whirring)

I prepare for my final transmission back to Earth.

(ethereal music)

The data I've collected will take five years to arrive,

longer to download, and generations to fully comprehend.

I could provide a summary, but what should I say?

I have found everything you've hoped for,

and also what you fear.

I have seen life of marvelous complexity,

and the traces of a devastating loss.

(ethereal music)

I could say Minerva is your second Earth,

and I hope, one day, you get to see it.

(dramatic music)

(upbeat ethereal music)