Nova (1974–…): Season 31, Episode 13 - Origins: Where Are the Aliens? - full transcript

This program reviews the Drake equation to provide an updated estimate of the likelihood that there is another civilization close enough to Earth for us to talk with. And it ponders the question; with so many strange life forms on earth how would we know an alien if we met one?

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Anyone who visits New York City

will see all manner of
different life forms.

And you don't have
to look far to realize

that our planet is teeming

with a diverse population
of living creatures.

And for centuries we've
been asking ourselves,

"How unusual is all this?

What about the rest of the Universe?

Is our little planet Earth the
only place where the action is?

Are we special?"

I find it hard to believe the fact that
we're the only people in this universe.

We're definitely not alone.

This is not just one universe.

You know what I'm saying?

There's, like, a hundred thousand
million galaxy, or galaxies,
in the universe.

There's trillions and
billions of universes.

Whatever. The point is, it's
inconceivable how big things are.

To think that we're
alone here is ridiculous.

Many people are ready, even eager, to
believe that we are not at all alone.

And that's the view prevalent in
lots of popular films and TV shows.

These are the voyages of
the Starship Enterprise.

It's an appealing fantasy.

Star Trek, Star Wars, Men in Black,

all portray a universe filled with a
multitude of intelligent life forms.

Show us the merchandise or you're
going to lose another head, dude.

Sometimes they're friendly
and sometimes they're not.

Screenwriters have come up with some
pretty interesting behaviors for their

but they often ignore some
basic principles of biology.

For example, in the film Alien,

a human being plays
host to a parasitic alien

until it's ready to be born.

This has long bothered
biologist Jack Cohen.

Alien is not concerned with the

You can't have a creature living
in your chest which is
bigger than your heart,

and you don't know it's there, and
your immune system isn't turned on,

particularly if it's never
seen a human being before.

It doesn't work biologically.

But it works as a film,

because you see the thing coming
out of the chest...aaagh...

and it's exactly what they
want. It's a horror film.


Another classic horror
image of extraterrestrials

shows them as giant insects?the alien
of choice for the film Starship

but according to the laws of physics,

this kind of anatomy is impossible.

It's like bringing a mouse up
to be the size of an elephant.

Its little thin legs wouldn't take
the weight, and they would break.

You have to redesign.

It's a lot easier to have a
terrifying film with giant ants.

As unscientific as the oversized
insects of Starship Troopers are,

at least they don't look like people.

By far, most films, even the ones
with huge special effects budgets,

depict aliens that actually
look like they evolved on Earth

because they have faces
that resemble ours.

Nearly all the vertebrates
we see around us,

humans included,

have faces with two eyes, two
nostrils, and a mouth below.

This configuration came
from a common ancestor

who lived hundreds of
millions of years ago.

Now, when we look at these aliens,

and they've got faces with two
eyes and a nose and a mouth,

they can't be aliens.

They must have developed on Earth.

They must share that same ancestor,

or they wouldn't have faces like that.

We expect a living thing, a dog or
a cat or even a fish, to have a face.

Therefore, when we invent something
for a film, we give it a face.

And that really enables the people
who are watching to get moved by it.

Real aliens can't be like that.

Real aliens?

What are we talking about?

UFO sightings and abductions
that show up in tabloids?

I think they have
traveled to this planet.

They might have been here years ago,

but they became extinct
just like the dinosaur did.

We've been visited.

Those lights in the sky
aren't all weather balloons.

Hmmm. There are some people who believe

that aliens are already among us,

but there's no credible evidence.

There's nothing in any of these stories

that can't be explained in
some other, more rational way.

And of course, some people
are just plumb crazy!

But is it crazy to believe that
somewhere, beyond our planet,

life has taken root?

Many scientists would say it's
not only possible but likely.

One of the believers is Frank Drake.

I first believed there was life beyond
Earth when I was eight years old,

not for any good reason,

only because my father told me

there were other planets
something like the Earth out there.

And to my young mind that meant
places just like where I lived,

with houses and streets and, in fact,
creatures that look just like me,

which was certainly wrong.

But I believed!

Drake's childhood dreams led him
to a career in radio astronomy,

and he soon began wondering
whether somewhere among the stars,

there might exist aliens who,
like us, had mastered radio.

Ever since humans learned
how to broadcast radio waves,

we've been leaking them
out into the cosmos.

Everything from Duke Ellington

to I Love Lucy

to the speeches of world leaders is,

thanks to our ingenuity,

now traveling across space
at the speed of light.

Drake reasoned that if aliens were
transmitting radio signals of their

we might be able to detect them.

And so he created the
first experiment for SETI,

the Search for
Extraterrestrial Intelligence.

For decades, SETI astronomers have
been scanning the stars of the Milky
Way Galaxy,

searching for signs of
advanced alien civilizations.

Their goal is the ultimate
prize in the life-finding game:

someone out there we can talk to.

Nothing to do but sit here
and wait for them to call.

And on cue, they've called!

SETI faces enormous challenges,

not least of which is the
sheer size of our galaxy.

The Milky Way has hundreds
of billions of stars,

swirling in a giant spiral about a
hundred thousand light years wide,

that's 600 quadrillion miles.

So what are the chances of finding
intelligent aliens in all that real

Early in his quest, Frank Drake came
up with an equation to guide him.

Actually, I first invented the
equation as the agenda for a meeting.

It seemed pretty obvious.

It was a meeting about life in space,

and I asked the question,
"What do we need to know about?"

And I realized if you multiply them
all together, you get the number N.

The now-famous Drake Equation lists
the different factors we'd need to know

to predict "N," the
number of intelligent,

detectable civilizations
in our own Milky Way galaxy.

It includes factors like,
"How many stars have planets?"

And, "How often will
life become intelligent?"

And how long a technologically
advanced civilization might last.

And if you put in scientists'
judgment the most plausible values

for the factors in this equation,

N equals 10,000 detectable
civilizations in our galaxy

?10,000 intelligent civilizations,
just in the Milky Way alone!

That's Frank Drake's best bet,

but it's far from conclusive.

If you plug different
values into the equation,

then it's easy to come
up with other results,

anything from a billion civilizations
all the way down to one: ours.

For a long time, the values for
most of these terms were unknown.

The Drake Equation was
something of a list of mysteries,

leaving the equation unsolvable.

But in the last few years,

our knowledge of cosmic origins
has been growing exponentially,

and we're on our way to solving
at least some of these mysteries.

Take just one term
in the Drake Equation:

the percentage of stars?other
suns?that have planets orbiting them.

If alien life is anything like us,

it needs some solid ground to call

and so we want to know how
many planets are out there.

Depending on who you talk
to, our sun's got eight,

maybe nine planets circling
around, including Earth.

Until recently, we haven't been able
to see any planets beyond our
own solar system, none at all.

The problem is planets in deep space

are rendered practically invisible
by the blinding light of their suns.

That's the challenge for the handful
of scientists trying to
track them down.

The team of Paul Butler and Geoff Marcy

started their quest in the 1980s

with little more than
their own enthusiasm.

We started off with
virtually no money at all.

The first proposal I wrote for a grant

to fund our planet search was
for $930 for the whole year.

When Geoff and I started
the planet search,

back in the fall of 1986,

at San Francisco State University,

we say we were
"unknown" is to overstate it.

We were sub-unknown.

The young astronomers were banking
on an experimental technique

they believed could scope out planets

by focusing on the stars they orbit.

As a planet orbits a star,

the planet pulls
gravitationally on the star,

making the star wobble.

You can tell a star has a
planet, or more than one planet,

just by the motion of the star,

which ought to be stationary

but wobbles due to the
pull on it by the planet.

The star's wobble, created by
the gravity of orbiting planets,

is so subtle, Marcy and
Butler can't see it directly,

so they use a special technique.

It's hard to detect
this motion directly,

so we thought we would
use the Doppler Effect.

As a star moves toward you,

the light waves get compacted,

and that means they get
shifted toward bluer colors.

And then, as the star
wobbles away from you,

the wavelengths of
light get stretched out,

and this is interpreted
by the eyes as redder.

Even using the Doppler Effect,

the only planets we can infer
would be ones with tremendous mass.

Marcy and Butler were confident

they had the best method
for hunting down big planets

and hoped they'd be
the first to succeed,

when the unthinkable happened.

A team of Swiss astronomers
beat them to the punch.

The first planet outside our
solar system had been found,

but by someone else.

Most astronomers were skeptical.

Although the planet was
massive like Jupiter,

the Swiss discoverers
claimed it orbited its star,

51 Pegasi, in only four days.

This seemed impossible.

Earth takes 365 days to orbit the sun.

And Jupiter takes 12 years.

Marcy and Butler felt certain
there must be some mistake.

Almost every year for the last 100

somebody has claimed to have
found the first extrasolar planet,

and the one thing all those claims
had in common was they were wrong.

And luckily, Paul Butler and I had
telescope time the very next week.

And we thought, "Well, we'll just go up
and take data on this star, 51 Pegasi,

and show that it probably doesn't
really have a planet at all."

And when we got back and we analyzed
all the data, we were stunned.

We were stunned because
their claim was right.

There really was a Jupiter-like
planet in a four-day orbit.

We were stunned because this was the
first legitimate, real planet ever

and that furthermore that these
planets could be much stranger,

much more bizarre, than any theories
that had ever been conjured before.

Marcy and Butler had spent years
looking for massive planets like

far out from their stars
with long, slow orbits.

Now that they realized that big
planets could make a complete orbit in
a matter of days,

they began to wonder:
had they missed something?

The evidence for new planets
might be buried in their old data,

but to find it, they'd need
hundreds of hours of computer time.

And we only had two little computers.

So we ran around madly trying to

and in some cases subverting, our
colleagues and stealing their computers

so that we could analyze
all of this backlog of data.

They worked furiously
around the clock for weeks,

re-crunching eight years of data.

I was literally in my office 24
hours a day for about six months,

reducing data.

Some nights, you know,
hardly sleeping at all,

and just making sure the
computers were all running.

God forbid the computers should sit

when we could've been
finding planets with them.

But the marathon was worth it.

Within a month and a half of the
discovery of the planet around 51 Peg,

we found two planets
sitting in our own data,

right there on our computers:

the planet around 47
Ursae Majoris?spectacular?

and then the other
planet around 70 Virginis.

Planets were finally being found,

but they were huge gas monsters,
circling close to their stars,

often in highly elliptical orbits.

Scorching hot or with unstable

they were friendly to neither
life nor other Earthlike planets.

Any poor Earth that got in the
way would be slammed to death.

I mean, a little Earth anywhere nearby
a Jupiter would get slingshot out of
the system,

or maybe the Jupiter
would hit that Earth

and probably spell doom for any life
on any terrestrial planets in those

And it really begs the question,

"Is our solar system with its nice
neat, phonograph groove-like orbits,

some kind of wacky
weirdo in the universe

or are there others like ours?"

In addition to its neat, round orbits,

our solar system provides
particular shelter for Earth,

thanks to the presence
and position of Jupiter.

Jupiter's enormous gravity throws
asteroids and comets off course,

slingshotting them out
of the solar system.

Without this protection, these cosmic
missiles would frequently smash into

and destroy life as we know it.

So, if Marcy and Butler want
to find Earthlike planets,

first they need to find
Jupiters more like our own.

The Holy Grail, for us,
is to find a sunlike star

that has a Jupiter as far from it
as our own Jupiter is from the sun.

That Jupiter would protect
any Earths that were in there.

And of course the real super Holy Grail

is to find a system that
has, not only such a Jupiter,

but also the Earth itself.

After almost twenty years of searching,

things are looking up.

We're finding new planets
like crazy, all the time.

Every week or two we find
another new one, on average.

Lookie at that one. That's a beauty.

Let's see how that corrects
up. That's a planet.

We have about 700 stars on our program,

and I'd say the thing that's
really most amazing to us is

how many of them appeared, like they
have planetary signals imbedded in

The team is tracking several
stars that appear to have Jupiters

right where they want them,

far out from their host stars

and in perfect position to shield
life-friendly planets like Earth.

We're always following
some exciting Jupiters.

We don't tell anybody about them,

but at any given time we have a half a
dozen Jupiters that look like our own

If their hunches are confirmed,

then not only are there other
solar systems that look like ours,

there may be lots of them.

Ninety percent of the stars
show no close-in Jupiters.

Those are stars that could easily
have an Earth in an Earth-like orbit.

I think of the 700
stars we're following,

I would bet at least half of them have
rocky Earth-sized planets going around

Just a decade ago
astronomers could not be sure

if there were any planets
beyond our solar system.

Today, we have a much
better picture of our galaxy.

And Geoff Marcy estimates that of the
several hundred billion stars in the
Milky Way,

about five percent have small,
rocky planets that might harbor life.

If he's right, that could mean
10 billion Earthlike planets.

But before you start packing your bags
to visit an extraterrestrial neighbor,
consider this:

just because a planet can support
life, does that mean it will?

It's a crucial factor
in the Drake Equation:

the percentage of planets
where life does arise.

On a planet where no life
exists, like our own early Earth,

how does life suddenly come into being?

Is the spark of life rare or common?

Twenty-five years ago, most people,
when they thought about the origin of

thought in terms of
inherently improbable reactions

that would actually occur
because of the fullness of time.

Andy Knoll is a paleontologist
who studies fossils for clues

to how early life evolved on Earth.

Before about 600 million years ago,

all life on earth was tiny,

single-celled creatures,

so small that Knoll and his colleagues
do most of their work with microscopes
or in chemistry labs.

The big surprise is that no matter
where they look for signs of ancient
life, they find it.

Our planet is about four
and a half billion years old.

We have evidence from the
oldest rocks that we know of,

at least the oldest
sedimentary rocks we know of,

that by about 3.8 billion years ago,

life had already gained
a foothold on our planet.

Scientists haven't figured out exactly
how that first spark of life happened,

but since it seems to
have sparked early on,

then maybe it isn't so hard.

Most people think that whether or
not we understand what the chemistry

that leads to life is,

that it's a chemistry that under the
right conditions will pretty much go

and...and is a fairly
probable chemistry,

and that therefore, life doesn't
take billions of years
to unfold on a planet.

It might unfold in thousands
of years or a million years.

A lot of people think if you
can't do it in a million years,

you probably can't do it at all.

So, what is required
to get it all started?

Here on Earth, the chemistry of life
relies heavily on the element carbon.

Carbon is one of the
most versatile elements,

each carbon atom can hook up with
one, two, or three or four other atoms.

It can even link up with other carbon
atoms creating long chains or rings.

Throw in a few other elements,

and you've got amino acids,

the ingredients of proteins,

the building blocks
of life as we know it.

Carbon is a very useful element to
sit at the center of life's chemistry.

There's a lot of it in the universe.

It's made very easily in stars.

It makes very complicated,
meshed-together compounds

which have the possibility of
changing each other's properties.

You can have a really complicated,
complex setup with carbon.

I'd expect that very nearly
all life forms we come across

that are matter-based are
going to be carbon-based.

If carbon helps make life happen,

then there might be a
lot of life out there.

Carbon is one of the most
common elements in the universe.

So if it's got carbon,
what else does life need?

Lots of oxygen in the air?

Seventy-two degrees?

We tend to think life belongs in a
place that's, well, comfortable for us.

But is that really true?

In the last few years, we've been
finding life practically
everywhere on Earth,

and not just the obvious spots.

Microbes are thriving under rocks
in the driest, hottest deserts.

Life's doing just fine in
the dark bottom of the oceans,

warmed by deep sea vents.

And now, life is turning
up in some of the coldest,

bleakest conditions imaginable,

including the ice sheets
of Antarctica and Greenland.

So now that we've found
life not just surviving,

but thriving just about
everywhere on Earth,

suddenly it's looking more likely that
life might thrive in lots of
places beyond Earth,

even if we would find
them a bit uncomfortable.

If life is common,

then we should be able to find signs
of it beyond our own little planet.

Unfortunately, the
evidence has been elusive.

It's seems as if one crucial
ingredient has been missing.

The most important requirement
for life is liquid water,

and that's the defining requirement
for life in terms of our solar system.

There's plenty of energy,
there's plenty of carbon,

there's plenty of other elements on
all the planets in our solar system.

What's rare, and which, as far as
we know, only occurs now on Earth,

is liquid water.

Liquid water is crucial
because it's an ideal solvent.

Molecules can easily move around
in it and react with one another,

allowing the complex chemistry
of life to do its thing.

For years, it seemed that Earth,

with its oceans of liquid water,
was an oddball and perhaps the only,

place in the solar system
where life had ever thrived.

Then we started to look more
closely at our neighbors.

In recent years, NASA spacecraft
have sent back images of Mars

with stunning detail,

and there are clear
signs of a watery past.

From orbit around Mars we can see
ancient rivers that are now dry,

canyons which look like they
had lakes in the middle of them,

even what looks like an ancient ocean
floor in the northern hemisphere.

We see unmistakable signs
that Mars was a wet place.

And now there's even more information
from NASA's twin rovers that roamed
the Red Planet,

taking pictures and probing the
rocks for their chemical makeup.

The photos reveal clear sedimentary
layers in the Martian rocks,

and chemical analysis shows

they must have been laid
down in the presence of water.

Mars might be too cold and
dry to harbor life today,

but if water was once there,
then perhaps life was, too.

And now, there's hope that life may
thrive even farther out in
the solar system.

I think Mars is the number one
candidate for the search for life
beyond the Earth,

especially if we're
going to find it soon.

But we do have a backup plan,

and in this case the back up plan is
Europa, one of the moons of Jupiter.

A little smaller than our moon,

Europa is covered with ice,

but there are cracks in its surface,

perhaps signs of ice sheets floating
on a deep ocean of liquid water.

What might be melting the
ice is internal friction

created by the gravity of
Jupiter and its other moons.

Europa's ocean is suddenly
considered a potential home for life.

The places where life can live and

are far more extensive
than we used to imagine.

We used to think a life-bearing
planet would be just like the Earth,

and a little closer to the
sun it would be too hot,

a little farther away
it would be too cold.

And now we realize, "Oh, gosh,

there's a place which has an ocean
with three times as much
water as the ocean of Earth,

and the water is warm."

And that's way out in the solar system

where we used to think the
temperatures were ridiculously low;

there could never be life there.

So the likelihood of life existing on
planets in space has just gone up

So, even though we've yet to
find life elsewhere in the
solar system or beyond,

we're getting more optimistic
that life may be widespread.

But if life is common in the galaxy,

what kind of life would it be?

Is it merely the kind of life we had
here for about three billion years,

microorganisms happily brewing away

with nothing bigger or more
interesting than bacteria?

Or is it the complex plant and
animal life we find in our oceans,

of all shapes and sizes?

Or could it be what SETI is banking on:

intelligent life that builds cities,
computers and radio transmitters?

We now know that the way we got to

from something like this,

was through evolution.

Does that mean evolution would work
the same way wherever life appears?

Frank Drake thinks so.

Once you have life,
evolution goes to work.

Life is very opportunistic.

It expands. It finds ways to survive.

It finds ways to cope
with changing environments.

And in the process it
becomes more intelligent,

and in the long run you end
up with something like us,

exploiting technology to live in
even more inhospitable habitats.

Drake's optimism shows
up in the estimates he's
plugged into his own equation.

His guess is that wherever life arises,

it will evolve into intelligent
life 10 percent of the time.

Not quite inevitable, but
a fairly common outcome.

It's hard to know how likely
or common intelligence is,

when it's shown up so
recently in Earth's history.

So the short history goes like this:

life early, but the familiar life
that we think of, plants and animals,

that is really a relatively
recent development on this planet.

And intelligent life,

people like ourselves,
technologically competent humans,

that's just a snap in the
full history of the planet.

After about three billion years
with only microscopic life,

Earth finally became home
to true plants and animals.

And after another five or
six hundred million years,

we came along.

One of the major mechanisms for
all these changes has been DNA,

the long chain of molecules that
carries the blue-print for every
living thing.

Every time a cell divides,
its DNA makes a copy of itself,

and in that copy, there
are always some mistakes.

Sometimes those mistakes
result in an animal or plant

that's more successful
than its parents.

It's these kinds of mistakes that have
allowed the tree of life to branch
out in so many directions,

creating the great diversity
we see on our planet.

So, if there's life on other
planets does it have to have DNA?

Would aliens have DNA? Well, I would
be surprised to find aliens with DNA
as their heredity,

because DNA is a useful
molecule, it can replicate,

it can do the mirror
image bit, it can do the...

It's a very useful trick, but
other chemicals can do that,

and I'd be surprised if aliens
latched onto the same one that we did.

To get from microbes to complex
animals and intelligent life,

you might not need DNA,

but there's one ingredient
that could be absolutely crucial

for the evolution of intelligence,

and it may be the rarest of all: time.

Some scientists say that the key to
our evolution

was Earth's long and
relatively peaceful history.

Among them is paleontologist Peter

In this big galaxy of ours

?hundreds of billions of stars?

surely earth is repeated many
places, many times. Why not?

Well, I think the question
is, "How much time do we have?"

For instance, we got to intelligent

organisms on this planet after
500 million years of animal life.

So you've got a long period of time.

Now that doesn't say you couldn't
get it sooner at other places,

but you still need
finite periods of time.

And to me that is the major argument
against there being intelligent

You can't go from a bacterium to
an intelligence in a million years,

maybe not even ten million years,
probably not even in a hundred million

How many other planets are going
to have such long periods of time?

Not many, I think.

In the half a billion years
when intelligence was evolving,

Earth's plant and animal life might
have been pushed back to square one,

single-celled organisms,
with one catastrophic event.

At least a couple of
times, we came pretty close.

This crater, about a mile across,

was made by a meteor that plunged
to Earth nearly 50,000 years ago.

As violent as that event must have

it was nothing compared
with earlier catastrophes.

Just ask the dinosaurs.

The dinosaurs ruled Earth for about
a hundred and fifty million years.

They had the size.

They had the power.

It seemed that nothing could stop them.

Then, sixty-five million years ago,

an asteroid about six miles
across headed toward Earth.

In the aftermath of a
collision of epic proportions

and widespread volcanic eruptions,

as many as two thirds of all
living species were wiped out.

The big guys didn't stand a chance.

Among the survivors were little

and with the dinosaurs conveniently
out of the picture, they thrived.

Over the eons, their descendents
evolved into lots of different animals,

including primates, including us.

That's how we got our start.

But what if you turned back the clock?

What if that asteroid had taken
a slightly different course

and missed Earth completely?

Little mammals may never
have gotten their chance

because the dinosaurs could
still be in charge today.

And instead of me, one of them
would be hosting this show!

Thank you, thank you very much!

In some ways, we owe our
existence to serendipity,

and some argue that this makes the
evolution of intelligence far less

Our brains evolved through many stages:

the little rodents,

the early primates,

and later on we branched from the apes.

This worked for us, but is it
the only route to intelligence?

Would an alien species have
to go through the same steps?

There's no way to know for
sure, but on our planet,

lots of animals have
remarkable brains and behavior,

including some that are very distant
from us on the evolutionary tree.

Among them are the
cephalopods, including octopus,

squid and cuttlefish.

Cephalopods are mollusks.

They're related to clams and oysters,

but they don't look
much like them at all.

And in evolutionary terms, they've
evolved in a very different way.

Roger Hanlon has spent the last 30
years studying the behavior of these

behavior that is their main
defense from ending up as dinner.

These animals are a yummy hunk of
protein swimming around in the ocean,

and once they're caught,
they have no defenses.

So they have to have
a good primary defense.

That's camouflage: don't be seen.

In the lab, Hanlon and his
team study how cephalopods,

like this cuttlefish, control
and change their skin patterns.

It's taking that visual information and
translating it to the skin on the back.

This is beautiful. Look at
that perfect white square.

To see how they apply their
tricks in their natural habitat,

Hanlon tails them with
his underwater camera.

His biggest challenge? Finding
them in the first place.

Octopus and cuttlefish
have an uncanny ability

to completely disappear
into the background.

We all think of the chameleon as sort
of the king or queen of color change,

but that's not true.

A cephalopod can show many more
patterns and can show them

An octopus can be so camouflaged
you literally cannot see it.

So every place they go,

they are morphing into something that
looks a lot like that environment.

So here's the scene. You've got
a rock with algae all over it.

There appears to be nothing there
except the swimming fish going by.

Okay, so take a look here
and just watch for a moment.

There it is.

Whoa! Isn't that amazing?

This animal was completely camouflaged
on that rock, and suddenly it was

This remarkable camouflage,

changing both pattern and
three-dimensional texture,

is performed by skin
unlike any other animal's.

It's an amazing skin, because there
are up to 20 million of these
chromatofore pigment cells,

and to control 20 million of anything
is going to take a lot of processing

We call it a computer.

Animals have brains.

These animals have extraordinarily
large, complicated brains to make all
this work.

For Hanlon, the brains and
sophisticated behavior of these
animals suggest

that there's more than
just one way to get smart.

Even an invertebrate animal
related to a clam or a snail

can develop an incredibly
complicated brain.

This is one of the
true wonders of nature.

It's hard to explain
why, but it's everywhere.

And what does this mean about the
universe and other intelligent life?

The building blocks are potentially
there and complexity will arise.

Evolution is the force
that's pushing that.

I would expect, personally, a lot of
diversity and a lot of complicated

It may not look like us, but my
personal view is that there is
intelligent life out there.

But intelligent life is not
necessarily life we can talk to across
the depths of space.

For that, you need technology.

As smart as an octopus or a dolphin is,

neither one of them is going to build
a radio transmitter or a space ship.

When paleontologist Peter Ward
looks at Earth's track record,

the odds for technological
aliens don't seem very promising.

There's maybe 30 million
species on the planet today.

And if we look at the fossils, there's
hundreds of millions of
species in the past,

but only one of them which
has risen to technology.

It's happened one time out of
hundreds of millions of possibilities

on planet Earth?one time, one time

So, that's an
astronomically small number.

Here on Earth, we are the only
species that has mastered technology.

Since it's so rare here,

should we really expect technology
to be common among the aliens?

Many would say "no," but the
folks at SETI continue to hope.

Searching for alien signals night
after night can test anyone's patience,

unless, of course, you find one.

Most evenings SETI will
get a false alarm or two,

but one night in 1997, they
received a signal so strong and true,

it looked as if their
long search might be over.

We were observing at another
telescope in West Virginia,

and we got this signal that started
to pass all the automated tests

that we use to determine is it really
extraterrestrial, is it just more

The lead astronomer that evening
was SETI director, Jill Tarter.

Following standard procedure, she
pointed the receiving dish away from
the star

where the signal appeared to originate:

if the signal remained, it was just
a stray transmission from Earth.

But when they moved the dish,

the signal went away.

And when it was pointed back at
the star, the signal returned.

Excited, the SETI
team repeated the test.

We went off in another direction,
and the signal went away.

And we came back and it was there.

And we went off in another
direction, and the signal went away.

And we came back and it was there.

And it was now getting very

Interesting because the signal might
actually be coming from deep space.

The excitement quickly spread back to
SETI headquarters in Mountain View,

I was back in Mountain View. We were
watching the signals on remote

Well, after about four or six hours
of this, still passing the tests,

needless to say, our blood
pressure definitely was rising.

And I was so excited that exactly
what I was looking for was right there,

staring me in the face.

By now the star had set.

The next night would tell the tale.

If the signal returned, perhaps
E.T. was finally on the line.

I, for one, couldn't sit down;
I was sort of pacing around.

A lot of people were huddled around
the computers. Nobody went home.

Nobody went out for a burger. In a
sense, you know, it could have been an
historic moment.

The historic moment
didn't survive the night.

Most of the time, SETI used a
second telescope, located in Georgia,

to weed out false alarms.

Unfortunately, the backup
antenna wasn't working.

So it took a little longer than usual
for the SETI team to discover the
truth on their own:

the signal was coming from
a distant research satellite.

The champagne remained unpopped.

Despite the disappointment,
SETI has never lost faith.

Its scientists remain convinced
that our universe is capable of

producing intelligent life
on many different worlds.

I truly believe there
are signals out there.

I also recognize full well that our
instruments, as powerful as they are,

are hardly beginning the search.

The number of stars we've looked
at, the number of radio frequencies,

is minuscule compared to the total

inventory of combinations of stars
and frequencies there are to search.

So we've hardly started.

We should not have succeeded.

Only through a great fluke of good
luck would we have succeeded by now.

Humans have been leaking radio waves
into space for most of the past

Compared to the history of our Milky
Way galaxy, about 10 billion years,

that's a tiny blip.

And we've been actively listening for
the radio signals from distant
civilizations for only about 40 years.

If the aliens are on the
other side of the galaxy,

any signal they send could take tens
of thousands of years to reach Earth.

It's as if the aliens
were throwing a dart

and trying to hit one tiny spot on this
enormous landscape of time and space.

Let's face it, the odds of our
capturing that signal aren't very good.

And yet, who can blame us for trying?

For me, it's the most
interesting question.

Are we alone? What's our place in
this universe? How do we fit in?

Are we just run of the mill?
Are we totally exceptional?

Or are we somewhere in between?

Exploring our own world
and the universe beyond

has been full of surprises.

Just a few hundred years ago,

we assumed that everything
about us and our surroundings

was special and unique.

Now we know there are
lots of stars out there;

many like our sun.

We're discovering other
solar systems with planets.

And the chemicals of
life, forged in stars,

are abundant in the universe.

If those common chemicals have caught
the spark of life somewhere else,

who knows how that life will evolve,

what path it will follow,

and whether we'll ever meet?

I feel like I'm six
years old when I say it.

I feel almost embarrassed. I just
want to know, "Are they out there?"

And all of my science training, and
math and skills as a researcher kind
of go out the door.

I just feel that this is a question

is going to be so profound for us
as a species, but also individually.

Each one of us will have to look
within ourselves and figure out what
it means to us.

Are we alone?

Are we rare?

Are we common?

We still don't know.

But perhaps someday we will.

And the answer, whatever it is,
will reshape our sense of ourselves

and our place in the universe.