All language subtitles for The universe S06E06 UFO The Real Deal

Male narrator: In the beginning,
there was darkness,

and then, bang,

giving birth to an endless
expanding existence

of time, space, and matter.

Every day, new discoveries
are unlocking the mysterious,

the mind-blowing,
the deadly secrets

of a place we call
The Universe.

Thousands of witnesses
have claimed to see UFOs,

and their accounts are often
strikingly similar.

- You have a crashed saucer
but also some crashed bodies.

You have government cover-up.

Narrator: Mainstream science

says the evidence
just isn't there.

- Oh, my God.

- It's a big jump
between a UFO

and an extraterrestrial
spacecraft.

Narrator: But if UFOs were
really extraterrestrial craft,

what kind of mind-bending
technologies would we find

under the hood?

- You'd have to have
some sort of technology

that was capable of canceling
the effects of inertia.

Narrator: When it comes to
unidentified flying objects,

what is the real deal?

[electronic whirring]

For millions of believers,
it all began on June 24, 1947.

A businessman and pilot named
Kenneth Arnold is flying solo

near Mount Rainier,
Washington.

Suddenly he sees
a group of nine aircraft

moving at incredible speeds.

- They were highly reflective,

and they were flying
at supersonic speeds,

in formation,
changing course abruptly.

The speeds were unattainable
at the time.

This was before the age of jets
and certainly supersonic jets.

- Being a trained pilot,
he did several things

to corroborate their existence
to make sure he wasn't seeing

some kind of
atmospheric effect.

He changed his—
his head angle.

He changed
the aircraft angle.

He even positioned
the aircraft

such that there was a light snow
in the background

behind the objects,

and they appeared dark
against a light surface.

Narrator: Before Arnold
can maneuver closer,

the objects are gone.

- It was basically unprecedented
in modern times.

No one had seen anything
like this.

Narrator: In the days
that follow,

newspaper reporters
misquote Arnold

as he tries to make sense
of the incident.

- In fact, he said it moved
like saucers skipping on water.

Now, of course,
the reporter

kind of messed that up
in reporting it

and said that
they looked like saucers.

Narrator: The term
"flying saucer” is born.

And Arnold's encounter launches
the modern UFO phenomenon.

Weeks later,
in the summer of 1947,

perhaps
the most famous incident

involving
an unidentified flying object

is reported near Roswell,
New Mexico.

- Roswell's become the poster
child of the UFO phenomenon

because it has all
the necessary ingredients.

You have a crashed saucer
but also some crashed bodies.

You have government cover-up.

There was some sort
of cover-up.

There was misinformation
given out by the authorities.

- The original account put out
by the Air Force at the time

was that this was
a flying saucer of alien origin.

And then later, very quickly,
it was denied,

and the story then was that
this was a weather balloon

which had crashed

and that there were no occupants
on board

and that there was nothing
extraterrestrial about it.

Narrator: Other witnesses
claimed to have seen

actual pieces
of a crashed spacecraft,

materials that are reportedly
unknown to science.

Both Arnold's sightings
and the Roswell incident

remain officially unconfirmed
and highly controversial.

- Just about every year,
there are thousands

of reported sightings,
mostly in the sky,

of objects that they assume
are extraterrestrial craft,

so-called UFOs.

The U is important,
of course.

They're unidentified.

- I personally have seen
a bright light

start at the horizon
and shoot off into the clouds.

Now, strictly speaking,
that was a UFO.

It's a big jump
between a UFO

and an extraterrestrial
spacecraft.

Narrator: Scientists argue
that most UFO sightings

either have earthly origins—

like satellites, balloons,
and aircraft—

Or cosmic origins,

such as meteors, comets,

or even an especially bright
planet Venus.

But when a UFO sighting
has no known explanation,

could it be
an extraterrestrial craft?

And if so,
what kind of technologies

could possibly explain
the behaviors

that witnesses
actually report?

How would such craft
be built?

And what problems
would they have to overcome?

- A lot of the behavior of UFOs
that people have reported

are things that are beyond
our current level of physics:

extreme rates of speed
or extreme acceleration,

extreme turn rates,

things that just we're—
we're not capable of doing

without extreme harm to a pilot
or destroying a spacecraft.

Narrator. Eyewitness accounts
of super fast accelerations,

lightning turns,
and sudden stops

seem to violate known laws
of physics,

but could aliens find a way
around these laws?

- So what we
have to keep in mind here

is the principle of inertia.

That principle, stated first
by Isaac Newton,

says that an object
at rest or in motion

tends to stay at rest
or in motion

unless acted on
by an outside force.

So to generate these kinds
of crazy changes in inertia,

you'd really have to act
on that object

with an immense amount
of force.

Narrator:
Following the same logic,

a fighter pilot traveling
near the speed of sound,

attempting to make a 90-degree
turn at the same speed,

would experience something close
to 300 "g's" of force.

The most that a human pilot
wearing a pressure suit

can manage
without blacking out

is around 10 "g's".

If his physiology
were remotely similar to humans,

an extraterrestrial pilot
undergoing a 300-g maneuver

would instantly perish.

His internal organs
would continue moving forward

and crush
against the skeleton.

- If they were similar
to us,

they'd probably have to have
a way of injecting fluid—

Internal fluid—
inside their bodies

so that they dealt
with this problem

of their organs
floating around inside,

and if they were
strapped in properly

and cushioned properly, uh,

end up not having
internal damage

when they accelerated
and decelerated.

Narrator: To effectively cancel
the inertial effects

on the craft itself,

the pilots might switch on
a technology

that is beyond the reach
of modern humans.

- So in order to cancel out
the effects of a 300-g turn

and not be squished
by that amount of force,

you'd have to have
some sort of technology

or a device that was capable

of canceling the effects
of inertia.

Narrator: The device would
have to manipulate

the force of gravity,
using a type of force field

to counteract
the gravitational forces

that rule the entire universe.

- This device, you could turn on
if you wanted to,

then turn it off
if you wanted to,

or maybe it would come
on and off automatically.

This is high technology
that's out of sight.

Narrator: But if science
can't yet explain

how these craft could overcome
the deadly problem of inertia,

can it help explain
their shapes?

Particularly the most famous
shape of all:

the flying saucer.

In the late 1950s,

the US. Air Force
tested the Avrocar,

but the design
had poor stability

and few aerodynamic
advantages,

proving that high speeds
are unattainable

for saucer craft
in Earth's atmosphere.

The delta wing, or wedge shape,
is a far stronger candidate,

a fact that is well known

by modern military aircraft
designers.

In fact, the percentage
of UFO sightings

reporting
a wedge-shaped craft

have increased
in recent decades,

a trend that mirrors
the emergence of swept-wing jets

and even flying-wing designs
like the B-2 stealth bomber.

- The shapes that people
have reported over the years

have changed,
with the most recent ones

being more wedge-shaped.

So, really, people's accounts
tend to reflect

the most advanced aircraft
of the time.

Narrator: Beyond movement
and shape,

any attempt to explain
the science of UFOs

has to deal with
the noise factor,

or rather,
the lack of noise.

UFO reports consistently claim
that the objects move

without making any sound.

- Almost all of these
sightings—

It's a real rule—-
there's no noise,

which you would expect to hear
from any fast-moving craft

in the Earth's atmosphere.

You would hear it.

- What actually happens
is that you get

what's called a sonic boom,

and that's a special
pressure wave

that sweeps through
the atmosphere

along with the craft.

So you're on the ground,

and that huge sonic boom
is the result

of that pressure difference

between the front
of the aircraft

and the back of the aircraft

as it pushes through
the atmosphere.

Narrator: Could an alien craft
somehow cancel out

the enormous pressure wave that
supersonic flight generates?

The answer could lie
in the technology used

in the latest generation

of digital noise-canceling
headphones.

- So there is such a thing
as a sound-canceling technology,

where you take
a particular sound

that you're interested
in canceling

and kind of broadcast
the negative of that sound

to cancel it out.

Now, I'm not aware of
any technology that's capable

of doing that
with shock waves.

Narrator. Canceling out

the earsplitting, body-shaking
effect of a sonic boom

would certainly require some
advanced engineering skills.

And if there is silence,
what about invisibility?

Some reports claim that UFOs
simply disappear into thin air.

One promising human technology
currently being researched

might explain such phenomenon.

- There is a technology
on the horizon

which might change things
visually.

And that is a kind
of light-bending technology.

As a class, they're called
met a materials.

If you want to think about
popular movies,

think the invisibility cloak
in the Harry Potter movies.

Narrator: Meta materials
use combinations

of polymer substrates,
gold, and copper

to forcibly bend electromagnetic
waves around an object.

The light is guided around
the object

rather than being reflected
or refracted.

But advanced materials,
stealth capability,

and mind-bending maneuverability
would all come to nothing

if our visitors were unable
to get to Earth

in the first place.

- I'd say that the chances
of another civilization

making it here to visit us
are pretty minuscule.

But if they did make it,

it would mean
that they had solved

a whole bunch of problems,

including material-science
problems

that we don't
have answers to.

So they'd have technology
far beyond ours,

perhaps even beyond what
we've dreamt of at this point.

Narrator: But scientists
can imagine

several ingenious technologies
that could bridge

the seemingly unbridgeable
distance between the stars,

including one explosive
propulsion source

that's so apocalyptic,

we might see them coming
light-years away.

For decades, countless
UFO reports have surfaced

from cities and countries
around the globe.

But not all UFO sightings
have been reported

from the surface
of planet Earth.

On July 19, 2009,

viewers of a NASA video feed
from the space shuttle Endeavor

reported seeing
a disc-shaped object

hovering above the shuttle's
mechanical arm.

- Roger on that visual...

narrator. Space-based
UFO sightings like this

have purportedly happened
throughout the history

of manned spaceflight.

Unspecified cosmic phenomenon?

Or could it suggest
the possibility

that huge extraterrestrial
star ships

are cruising
the Milky Way galaxy?

- Space travel
between the stars,

it's a staple
of science fiction, right?

You see it every night
on television.

You see it in the movies
all the time.

But could we really do it,

or could any species
really do it?

Well, the distances between
the stars are enormous,

really enormous.

Interstellar travel
doesn't violate physics.

It isn't that you can
rule it out and say,

"There's absolutely no way
they can come here."

It's just that
it's very, very hard.

Narrator: Just traveling from
the Earth to Alpha Centauri,

our closest neighboring star
at nearly 4 1/2 light-years,

is beyond the reach
of our most powerful rockets.

- If an advanced civilization
were to visit us

from a distant star system,

we can pretty much rule out
that they would use

chemical rockets
to get here.

Despite the impressive pillar
of fire and smoke

that we see during
Apollo Saturn 4

or shuttle launches,

chemical rockets don't get you
very far in a solar system.

- To give you some context
for that distance,

our furthest known space probe
is Voyager 1,

launched in 1977.

It's been flying for 34 years
at 38,000 miles per hour,

and it's only now starting
to leave our solar system.

- If its destination
were Alpha Centauri,

it would take
over 56,000 years

to reach even the closest
star system.

To engage
in interstellar missions

on time frames
of a human lifetime,

around about 50 years,

we can see that we need

to increase the speed
that we can travel

by at least a factor
of 1,000.

Narrator: Scientists
have determined

that the speed of light
is a mind-blowing

186,000 miles per second.

A spacecraft traveling
the star systems

would have to reach
a significant percentage

of that speed even to reach
the nearest star.

The biggest obstacle
is weight.

A chemical rocket exacts
a huge weight penalty

because its entire fuel supply
must be carried on board.

- We can calculate that

even to reach 6%
of the speed of light

using chemical rocket fuel,

you would need
more rocket fuel

than exists mass
in the universe.

So we really know that
it's actually impossible

to reach another star system
using chemical rocket fuel.

Narrator: If extraterrestrial
visitations are even possible,

their spacecraft
must solve this problem.

In 2011, NASA's NanoSail-D

became the first solar sail
to orbit the Earth.

The ultra thin 100-square-foot
sail uses sunlight,

or photon pressure,
as a source of propulsion.

- One of the immutable
limitations of rocket propulsion

is the fact that any rocket
has to carry its fuel with it.

A solar sail
can take advantage

of the naturally occurring
resources,

namely photons emanating
from the Sun,

which can be used
to propel that solar sail.

Similarly, a hang glider can fly
without any fuel or an engine

just by taking an advantage
of the natural resources

we're surrounded by,
namely the atmosphere

and the laws of aerodynamics.

Narrator:
To achieve sufficient speeds

to tow a spacecraft
supporting life-forms,

the sail
would have to be huge,

up to hundreds of miles
in diameter.

And because the photon pressure
from a star would decrease

the further
the sail traveled,

some have envisioned
a concentrated laser beam

directing energy
at the sail.

- Eventually and sadly,

this hang glider
and all hang gliders

at some point have to land,

but a solar sail riding
a beam of laser energy

could conceivably travel
to the stars.

Narrator. The max speed
of a solar sail:

about 10%
the speed of light.

Travel from Earth
to Alpha Centauri

using laser-generated
photons:

about 45 years.

Currently, NASA
and other space agencies

have plans for launching
more solar sails.

But there are other,
more powerful sources

of propulsion
in the universe.

- In the 1960s, a method
of propulsion was proposed

where a spacecraft
would literally

drop a series of
explosive charges out the back,

and the force
of the explosions

would push the spacecraft
forward.

The prototype was called
the Orion drive,

and there were actually
a series of experiments done

with conventional charges
to show that it would work.

The Orion drive, however,

was proposed to use
nuclear charges.

In order to simulate an
Orion-style propulsion system,

Paul and Jim here are rigging up
a demonstration

where they're going to put
a small chemical charge

inside this barrel,

and we're going
to lift this off the ground

50, 60 feet in the air.

We're going to actually
calculate

the energy released
in this explosion

and compare it
to a nuclear charge

you might find on an actual
Orion spacecraft system.

Our Orion spacecraft simulator
is rigged and ready to go.

We're going to light off
the charges inside,

blow the can up
into the air,

and compare that
with the energy release

from a typical
nuclear explosion

that would be used
on an Orion-style drive.

[muted bang]

Narrator:
The Orion spacecraft,

studied at Los Alamos
in the late 1950s,

proposed nuclear fission
as its propulsion source.

Fission energy is produced
when the nucleus of an atom

splits into smaller parts,

producing free neutrons
and protons

that release tremendous
gamma ray energy.

[booming and crackling]

[whooshing]

- [laughs]

The explosive charge
in this 35-pound barrel

lofted it about 60 feet
in the air.

A small nuclear charge
in the Hiroshima range

would liberate about
27 million times more energy.

Clearly, that's a practical
propulsion drive

for interplanetary
or even interstellar travel.

Because of
the huge explosions

that an Orion drive
would require,

on the back
of the spacecraft,

you would have
a huge, thick metal plate

that would absorb the thrust
of the explosion

and a series
of shock absorbers

to keep the crew
from getting jolted

each time
the charges went off.

Narrator. The max speed

of a nuclear-powered
fission spacecraft:

about 5% the speed of light.

Travel time from Earth
to Alpha Centauri:

about 90 years.

Despite its powerful
fuel source,

the fission craft is actually
slower than a solar sail.

Boosting speed would mean
turning to another

more intense
nuclear reaction.

- Fission technology
is well known and understood.

And we've been using it
to generate power here on Earth

for decades, but there's another
kind of nuclear technology,

and that's nuclear fusion.

- Fusion is the power source
of the Sun.

In the core of our Sun,
the temperatures are so high,

atoms are moving so fast
that they slam into each other,

creating new elements
and liberating energy.

Narrator: The opposite
of fission,

fusion energy is produced
when two atomic nuclei

fuse together to form
a single, heavier nucleus.

The result is a huge liberation
of energy.

A fusion-powered spacecraft
was proposed in a 1970s study

called Project Daedalus.

Its mission called for a trip
to Barnard's Star,

some 5.9 light-years
distant.

Instead of nuclear bombs,
the fusion-powered craft

creates the propulsion on board
in a reaction chamber.

- The fuel pellets for
the Daedalus-class stars hip

consisted of pellets composed
of a deuterium-helium-3 mix.

These would have been
ignited

by what we call
relativistic electron beams.

These are extremely
high energy electrons

that would have hit
the deuterium-helium-3 pellets,

caused them to fuse,

and a huge amount of energy
would be released.

The Daedalus design called
for 250 of these pellets

to be released every second
for over two years.

The spacecraft would
have weighed 55,000 tons,

most of which
would have been fuel.

Narrator. The weight penalty
for such a spacecraft

would be high,
but an advanced civilization

could eliminate the problem
by mining the hydrogen fuel

during its interstellar
journey.

Deuterium,
or heavy hydrogen,

exists in abundance on Earth,
notably in seawater,

but helium-3
is a much rarer isotope.

In our solar system,
it can be found on the Moon

and in vast quantities
on Jupiter and Saturn.

Scientists have proposed
using huge hydrogen scoops

to mine the helium-3 needed
to cross the void of space.

- So it's conceivable
that if you had a craft

that was powered
by nuclear fusion,

you could go
to another star system

and then use the hydrogen

available from that star
to refuel.

Narrator: The self-contained
fusion-powered spacecraft

could avoid
a huge weight penalty

and reach speeds that could
allow near-star exploration

in a reasonable time frame.

The max speed

of a nuclear-powered
fusion spacecraft:

up to 15%
the speed of light.

Travel time from
Earth to Alpha Centauri:

about 35 years.

The immense costs,
the logistics,

and even the politics
of nuclear-powered spaceflight

long ago caused humanity
to scrap any and all plans.

But a sufficiently advanced
society

could trade
nuclear propulsion

for what seems like
an impossible paradox:

traveling at light speed
without moving at all.

Can UFOs actually achieve

the immense speeds required
for interstellar travel?

One potential answer
may be buried

30 feet beneath the ground
in America's heartland:

the Fermi lab Tevatron Collider
outside Chicago, Illinois.

Racing just below
the speed of light,

particles of protons
and antiprotons

are launched
in opposing directions.

They meet in a high-energy
collision.

The impact produces
gamma rays,

the highest energy source
known in the universe

and potentially the key
to interstellar travel.

- The best way of making
antimatter here on Earth

is to employ probably
the most famous equation

that Einstein taught us,

which is
E equals MC squared,

which tells us that
for a certain amount of matter,

we can get energy.

It's a great idea because
it's incredibly efficient.

You essentially take all
of the mass in those particles

and convert it into energy.

Narrator: But how can antimatter
exist in the universe

if it must be artificially
manufactured?

That's the question that
Stefan H. from Philadelphia

texted The Universe.

- Stefan, antimatter
definitely exists,

and when it meets up
with normal matter,

it explodes in a burst
of electromagnetic radiation.

Now, we can make small bits
of antimatter in laboratories,

but we can also collect
antimatter from space.

Some cosmic rays,

which are charged,
very energetic particles

coming from space,

actually consist
of antimatter.

Narrator: Currently,
the super collider

is the only practical way
to produce antimatter.

And right now, it's created
in very small quantities.

- If we could figure out
a way

to both create and store
enough antimatter,

we would have
a storable fuel,

which, when mixed
with ordinary matter,

would liberate
a huge amount of energy

at a rate way beyond what
either fission or fusion can do.

- Because we know
antimatter exists

and we know antimatter
can be created and stored,

it is conceivable that
an advanced civilization

could create and harness
the power of antimatter

in sufficient quantities
to create an antimatter rocket.

Narrator: An antimatter ship

could achieve
unbelievable velocities,

cruising just below
light speed,

nearly matching
the speed of a star beam

streaking across the galaxy.

Travel time from Earth
to Alpha Centauri

4 1/2 light-years distant:

about 5 years.

In human terms,
the cost of creating

enough antimatter particles
to power such a stars hip

would be astronomical.

It might be affordable
in alien currency,

but an antimatter spacecraft
like this

comes at a high price.

The gamma rays from antimatter
propulsion are so dangerous,

they could destroy
the cell structure

of any living beings
aboard ship.

This stars hip
would have to include

an advanced shielding mechanism
to keep the crew alive.

And at such high rates
of speed,

there are equally destructive
threats in the universe.

- Space is pretty empty,

but if you were moving
close to the speed of light,

you'd need an extremely
effective shielding system

that would allow you
to be protected

from interstellar dust particles
that would all but annihilate

a spacecraft traveling
that fast.

Narrator: But if space debris
is so dangerous,

why not avoid it completely?

The solution might be one
familiar to Star Trek fans,

namely a stars hip that
could achieve light speed

without even moving.

- In effect, one would create
what is called a "warp bubble,"

the name taken
straight out of science fiction,

and that would involve

compressing a region
of space-time

in front of a spacecraft

and expanding a region of
space-time behind a spacecraft

while the spacecraft itself
sat stationary

inside this flat bubble.

So one would effectively be
riding a wave of space-time.

Narrator: A warp drive may seem
like pure sci-fi fantasy,

but in 1994, a well-respected
young physicist

named Miguel Alcubierre
published a serious proposal

outlining how to travel
in a controllable space warp.

There are huge obstacles
to Alcubierre's

warp drive solution.

The biggest is called
dark energy,

a cosmic phenomenon
recognized in 2011

when three scientists
were awarded the Nobel Prize

for proving its existence.

- The simplest explanation
that's been proposed

for the phenomenon
of dark energy

is that there's an intrinsic
property of space itself

that makes it want to expand.

You can actually see it
by looking at receding parts

of the universe
and seeing that

there's this
extra acceleration component,

but it isn't
a stored energy source

like solar energy
or other kinds of energy.

- And so it's not
inconceivable.

It's not beyond the realms
of possibility

that some advanced
civilization

existing somewhere
in the universe

has learned how to harness
dark energy

to create an exotic form
of propulsion.

Narrator:
But there's another obstacle

to a workable warp drive.

The only known way
to pull a spacecraft forward

within a warp requires
harnessing the intense energy

of a black hole.

- The sort of simple notion

is somehow to make a very
concentrated bit of matter,

extremely concentrated,

on the level which would cause
a black hole.

If you could generate
a black hole on a small scale,

so to speak, you could dangle it
in front of the ship

and use its space distortion
to sort of drag the ship along.

Narrator: And exactly how fast
could a warp drive

tow an extraterrestrial
spacecraft?

- The clear implication
of Alcubierre's work

was that
it should be possible,

if you can make this design
of a warp drive,

to achieve speeds almost any
multiple of the speed of light.

Narrator: Travel time
from Earth to Alpha Centauri

aboard a light speed craft
powered by a space warp:

about 4 1/2 years...

Or less, as long as everyone
on board doesn't incinerate.

- One problem with
the Alcubierre drive is,

within that warp bubble,
temperatures would rise

to far hotter
than the core of our Sun.

That's hot.

Narrator: Just one more
small problem to solve

for the chance
to reach planet Earth.

But what if such an alien
spacecraft were to arrive

in Earth's atmosphere,

riding in a warp bubble,
towed by a black hole?

It might not be the first
mass-witness UFO sighting,

but it would certainly
be the last.

March 13, 1997,

thousands of people
witness an optical phenomenon

drifting across
the Arizona skies.

Reports of a series of bright
lights in geometric patterns

are widespread, including
multiple sightings over Phoenix

of a craft up to a mile wide

with lights winking on and off
in sequence.

- Reconstructing
the events of that evening,

the lights of the Phoenix lights
were almost certainly flares

dropped by
an Air Force A-10 aircraft

in conjunction
with the human tendency

to envision a solid shape
connecting them.

That's the best explanation
for the Phoenix lights.

Narrator. For many,
the Phoenix lights incident

was direct proof that

a huge extraterrestrial craft
had arrived.

Some even called it
a mother ship.

The purpose of an
extraterrestrial mother ship

is fundamental to the theories
of alien visitation.

It's the only way to bridge
the vast distances

of interstellar space.

- The term "mother ship,"
I think, came into being

around the same time that
"flying saucers" as a term

came into being.

And I think
the universal notion was,

you couldn't make
an interstellar trip

in a person-sized craft.

You have to have something
really large.

- An apt earthly analogy
of a mother ship

is that of
an aircraft carrier.

An aircraft carrier travels
the vast distances

across the oceans,

but its purpose is to transport
smaller aircraft

which can then go on

and engage in whatever
their missions may be.

Narrator: If the journey
to Earth is long,

on the order of centuries
or even millennia,

the mother ship
would be much more

than just
an aircraft carrier.

- There's the generational
or "ark ship,"

which is
a very large spacecraft

that is essentially
an enclosed ecosystem,

in which generations
of inhabitants

expect to be born, grow old,
and die

over the long period
it takes the spacecraft

to reach its ultimate
destination.

Narrator:
Perhaps with technology,

such as
suspended animation,

biological alien passengers
could be put to sleep

and revived
after the vast journey.

Surviving such a journey
would also mean surviving

the destructive energy
powering the spacecraft itself.

One logical design solution,

a cigar-shaped mother ship,

is precisely what many UFO
witnesses claim to have seen.

- For any advanced
propulsion system,

you would want
to situate the crew

as far away as possible
from the engine source.

So one possible design would be
a very long, thin design,

with the engine located
at one end of the spacecraft

and then some kind of truss
connecting the crew section

as far away as possible
so as to avoid damage

from high-energy neutrons,
X-rays, or gamma rays

from the advanced
propulsion system.

Narrator: If such ark ships
have in fact

visited planet Earth,

the evidence would be
overwhelming and undeniable.

- Something all these exotic

and advanced propulsion
technologies have in common

is that they all radiate
prodigious amounts of energy,

and so we'd be able to see them,
like beacons on a lighthouse,

from sometimes
light-years away.

- The concentrated emission
of X-rays, gamma rays,

or subatomic particles
would be suspicious,

'cause we don't see that
in our environment locally

under any normal
circumstances.

Narrator. Beyond the obvious
visual evidence,

the physical effect
of a mother ship approaching

so close
to the Earth's surface

could be a terrifying form
of apocalypse.

- If, for whatever reason,

this extraterrestrial technology
or civilization

chose not to turn off
their engines,

it could be catastrophic
for life on Earth,

as we would be bathed

in high-energy neutrons,
X-rays, and gamma rays.

- If it's something which
is a version of a warp drive,

then you're talking about
space distortion,

and you wouldn't want to be
too close to any major mass,

including a planet.

Narrator: Such catastrophic
visitations

assume that aliens are willing
to risk their own lives

in interstellar space,

but there might be
a better way.

They could stay at home

and explore the cosmos using
a race of thinking machines.

For many ardent believers
in the UFO phenomenon,

the Roswell, New Mexico, event
in the summer of 1947

is the defining alien encounter
in human history.

In popular culture,

the most lasting detail
from the purported crash

came from the descriptions
of extraterrestrial bodies

found at the scene.

In the ensuing decades,
this vision of alien beings,

known as "the grays,"
became the accepted standard

in science fiction and recurring
alien encounter reports.

The over sized heads
may explain

an expected feature
in alien biology:

greater intelligence.

The larger skulls would contain
larger, more advanced brains

compared to ours.

Mastering the profound
challenges

of interstellar travel
would certainly require

great intelligence,

but might it require something
that is beyond organic biology?

- One area of science fiction
where we might be making

kind of a big mistake
is to assume that the aliens

are biological,
that they're living things.

- I think that the possibilities
for the kinds of organisms

which might travel between
the stars are really wide open.

And one possibility that
has appeared on occasion

in science fiction
is machine intelligence.

Narrator: According to
a recent earthly equation

known as Moore's Law,

the number of transistors
on a single computer chip

doubles every 18 months,

meaning computer processing
speed doubles.

This trend has continued
for more than half a century

and is expected to continue
through 2020 or later.

The exponential explosion
of processing speed

is opening the door
on a staple of science fiction

called artificial
intelligence.

- So if you invent
a thinking machine,

100 years later,
that machine

is not only smarter
than you are,

it's smarter than all humans
that have ever lived.

And that's the difference
between artificial intelligence

and real intelligence.

Artificial intelligence
can evolve enormously faster.

But I think the form of A.I.
that we find

most both menacing
and promising

is the kind of A.I
that could in fact

do what our brains can do,
can think the way we can think.

Narrator:
At Stanford University's

Artificial Intelligence
Laboratory,

the future of
truly intelligent machines

is rapidly approaching.

- There are a few things
that make A. difficult.

One is, we don't really know yet
how to make computers

learn as effectively
as humans can.

It seems that our computers
today just aren't as fast

as we would like them to get

to simulate
the learning processes

that take place
in the human brain.

Narrator: To demonstrate

early-stage artificial
intelligence,

Stanford students designed
a fighting robot,

one that attempts to learn
as it fights.

- Okay, so what
it's doing now,

it's trying
to defend itself,

so it's reacting
to your motion.

So depending on how you move
your sword,

the robot will adapt to your
motion and to your behavior.

- How important
a step on the road

to true artificial intelligence
are robots like this, Torsten?

- So here we are using
artificial intelligence methods,

like learning methods,

to adapt to the environment
of the robot,

but we are still
not at a stage

where the robot
is really thinking.

- Today's computers are still
far less intelligent

than almost any human.

But in the future,
I think computers

could eventually reach
and maybe even surpass

human intelligence.

And if that's the case,

imagine that each of us
has a computer in our wallet—

A cell phone or wallet-

that was as smart as Einstein
or even smarter.

How will civilization change,

and what are the amazing things
we could do then?

Narrator:
Advanced as it is on Earth,

the fencing robot
is but a crude analogy

for the type
of machine intelligence

that could pilot
an interstellar spacecraft.

The immense obstacles
of space travel,

including the sheer time scale
and cosmic hazards,

build a strong case that
a race of intelligent machines

will make first contact.

- But honestly, if interstellar
travel really takes place,

it seems sort of reasonable

to not send
the biological beings.

I mean, they're fragile.

They have finite lifetimes.

- Just as NASA
sends robotic probes

to explore the solar system
in advance of human explorers,

our first contact
with an alien civilization

may be with
its robotic probes.

Narrator: Biologic being
or A super being?

Our vision
of an extraterrestrial

will remain mere speculation
until first contact is made.

But how long will we wait?

And despite a lack
of hard evidence,

just how likely
is the existence

of another intelligent
civilization?

Some believe
it is highly likely

that the universe
teems with life.

- The galaxy has been around
for a long time.

The solar system's been around
for quite a long time

but the galaxy much longer.

And the stars in it,

many of them are much older

than the Sun
and our solar system.

So the chances are,
if civilizations are out there,

they've been around
for longer than we have.

If they exist, say,
for 100,000 years,

then the chances
are pretty good, I think,

they will have learned
to either communicate

across interstellar space
or possibly travel.

Narrator:
Until first contact occurs,

humanity will continue
to scan the skies for UFOs.

None have been proven to be
extraterrestrial craft so far,

but that does not rule out
the possibility

that humanity may one day
discover evidence

of an intelligent
civilization,

either in the far flung heavens
or much closer to home.