Original subtitles

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.