Original subtitles

A gleaming blue planet,

rising in black space above the moon's horizon.

The Earth.

This was the first view humans ever had

of their planet as a whole.

People began to wonder whether someone

or something out there might not

in fact be observing our world already.

In the same year, an amazing discovery had been made.

Strange radio waves emanating from outermost space.

At regular intervals.

Could these be signals from some extraterrestrial beings?

Was it an intelligent signal

from outer space or not?

Strange pulses from outer space.

Earth's astronomers now competed

to identify the source.

Research into the pulses lead to the discovery

of a strange new celestial body.

One that produces something that

has long attracted human interest, gold.

A mysterious celestial body

that sends out pulses and produces gold.

What could this body look like?

This is a voyage to explore the strangest object

in outer space.

Something mysterious, hidden deep within nebulous gasses.

Explorers entering this region

would be buffeted by fearsome storms.

And a blinding, pulsing force,

emanating and expanding waves.

As they approach the object,

they would see a rotating beam.

And a star, with a diameter of just 10 kilometers,

with a glinting mirror-like surface.

This marvelous object really does exist in space.

And now we will learn how it was discovered.

Cambridge, England.

Where the likes of Newton and Darwin

launched more than one scientific revolution.

A controversy in 1968 also started here.

It was in the Cambridge suburbs

that the antennas of the Mullard Radio Astronomy Observatory

picked up some bizarre signals.

Antony Hewish is one of the discoverers of those signals.

There was one in particular

which my student Jocelyn pointed out,

which was a little bit unusual.

The perceptive graduate student Hewish

refers to was Jocelyn Bell.

Day in and day out she was studying radio waves

from outer space.

And so I was looking for sources

that twinkled, that varied.

And rather to my surprise,

I found something that looked a bit

like a twinkling radio source,

but was not exactly like it.

This is the actual record of Bell's observations.

Usually there were hardly any undulations,

but on this day she detected some regular pulses.

The regularity of the intervals is indicated by the arrows,

and the signals were strong.

This was a first.

It looked artificial, unlike any natural phenomenon.

Crazy! Totally unlike anything astronomical.

Never been seen before.

Probably impossible.

Pulse, pulse, pulse, pulse.

The pulses continued the next day,

and the next, the exact same spacing.

Close analysis revealed a period,

or interval, of exactly 1.34 seconds.

It was amazingly precise.

My immediate assumption, as a radio astronomer

whose been in the game for several decades,

is that it's some radio interference.

Somebody is generating a signal somewhere.

Suspicion fell first on the spark plugs

of passing motor vehicles.

But testing found that an engine's spark plug

could not produce so regular a pulse.

Next they considered radio waves from nearby observatories.

Perhaps they emitted radio waves

during the course of their observations.

But all the observatories they asked denied the possibility.

Third suspect, the Moon.

Radio waves from sources on Earth,

might be reflected back to Earth by the Moon.

But the pulses were coming even on moonless nights.

They considered ships' radars, arc welders.

And amateur radio operators all to no avail.

Finally they found proof that the signals

were in fact coming from outer space.

The stars take 23 hours and 56 minutes

to go round and come back to the same spot in the sky.

Not 24 hours, they get four minutes earlier each day.

And this object was moving like the stars.

So it's either something very very curious,

or it's stellar.

And here we have this signal.

It looks quite unnatural.

Was it an intelligent signal from outer space, or not.

That thought had to be taken seriously.

Someone started to use the name, little green men.

I'm not sure if it's this recording or not.

Yes there we are,

someone, you see, I think that may be my writing,

has written green men on the report.

Could Hewish and his associates

prove a sentient alien source scientifically?

It occurred to them that such a source

most probably resided on another planet.

I think if you have alien intelligence,

it's likely to be on a planet

which is in orbit about a star.

And that orbital motion could be detected.

Hewish thought as follows.

Aliens are unlikely to be living right

on a burning star like the sun.

They would be living on a planet orbiting that star.

And there was a perfect way to test whether the pulses

did or did not come from such a source.

Anything moving will give off sounds

or radio waves of varying periodicity.

For example, the sound of an approaching train

will get higher.

As the train approaches,

the spaces between the sound waves it emits become shorter.

That shorter cycle gives it a higher pitch.

By the same token, as it pulls away,

the spaces between sound waves get longer,

and the pitch lower.

It's called the Doppler Effect.

So if those pulsing radio waves were

from aliens on a planet in orbit about its sun,

the space between pulses should grow longer

as the planet moves farther from Earth.

And as it moves closer, the spaces should get shorter.

If this was the pattern, than one might indeed conclude

that the signals were being sent by aliens.

This was round about December, 1967,

I was doing that work.

And after three weeks, I could detect no orbital motion.

If the signals did not originate

from a planet in orbit, then they did not come

from an alien life source.

That meant they had to emanate from a star.

But what sort of star could send out these regular pulses?

The mystery only deepened.

It was then that they discovered a second similar pulse,

and it came from a totally different direction.

The next day they found third

and almost immediately a fourth.

The objects emitting these bizarre signals

were all over the universe.

The mysterious objects came to be called pulsars.

But there was considerable surprise

and interest in this result.

Word went round the astronomical community

very very quickly about this surprising result.

And the whole world knew about it.

And of course every radio telescope that could point

in the right direction looked at these pulsars.

A new celestial body emitting a mysterious pulse.

What could it possibly be like?

Pulsars were a strange new celestial body.

A clue as to what they were like,

came from an unexpected source.

Thirty years before the discovery of the pulsars,

a genius of an astronomer posited the existence

of a fantastic type of star.

In 1934 the Swiss astronomer Fritz Zwicky

made certain theoretical calculations

about the final stage of a type of giant star.

When the giant star uses up it's fuel,

it erupts in a giant explosion called a super nova.

After the explosion, what's left is an extremely small star.

Furthermore, this small star is of a most peculiar kind.

According to Zwicky's calculations,

such a star might have the mass of our sun,

but a diameter of just 10 kilometers.

The star would be composed exclusively

not of ordinary atoms, but of particles neutrons.

So could the pulsars be the neutron stars

predicted by Zwicky?

Stars, neutron stars, can rotate fast enough

and produce directed radiation.

So that what you're looking at,

is essentially a lighthouse.

Like a terrestrial lighthouse.

Neutron stars have magnetic fields.

The stars rotate rapidly, all the while

emitting electromagnetic radiation,

including radio waves.

Like the light from a lighthouse,

These radio waves will seem to pulse with every revolution.

The neutron star was a winning candidate for the pulsar.

If a radio telescope could detect those pulsing radio waves

amidst the remains of a supernova explosion,

then it would be clear proof that the pulsar

was none other than the likely product

of that supernova explosion, the neutron star.

Telescopes were pointed to the Crab Nebula

in the constellation Taurus.

The Crab Nebula is formed of the remnants

of a supernova that occurred in 1054.

Ancient texts record that supernova.

It was so brilliant that it could be seen

even in the middle of the day.

The Crab Nebula is some 10 light years across.

That is vast.

It's 600,000 times the distance from the Earth to the Sun.

Astronomers around the world are surveying it closely,

believing that somewhere in these remnants of a supernova

there must be a neutron star.

But no one has yet found a pulse.

Perhaps the pulsar is not a neutron star after all.

The jewel of the Caribbean, Puerto Rico.

In Arecibo, in the Western part of the island,

is situated a gigantic structure,

the Arecibo Observatory.

With a dish antenna 305 meters across,

this is the world's largest radio telescope.

Compare that dish antenna to a baseball stadium.

The stadium fits in with room to spare.

This giant radio telescope was used to search for a pulsar

in the Crab Nebula.

But even this telescope could not find a pulsar there.

Richard Lovelace of Cornell University spent eight months

at Arecibo observing the nebula.

Why could a pulsar not be found in the Crab Nebula?

Lovelace consulted with his colleagues.

One theory emerging from their discussions

was that it was there,

but with a much shorter period than expected.

We should look for much shorter periods.

Because in fact the pulsars found by Hewish and Bell,

those were one second period

and one of them was a quarter of a second.

So Lovelace and his colleagues

developed an analytical program to identify pulsars

with merely 1/5 the period of most Hewish and Bell pulsars.

On November 9th, 1968, after Lovelace

had completed his Gallop computer program,

he focused Arecibo's giant spherical antenna

on the Crab Nebula.

Gallop worked splendidly.

Capturing and analyzing radio waves in rapid succession.

Here are the computational results.

Pulses were assigned number values

in order of magnitude from one to nine.

The strongest pulses of all were labeled X.

And here is the much sought after X.

Detailed analysis showed that this pulse

from the Crab Nebula occurred at an interval

of 0.03 seconds.

That is a mere 1/40 of the pulsar periods initially observed

by Hewish and his associates.

The reason this pulsar had not previously been detected

in the Crab Nebula was because the star producing it

was spinning so fast, yielding such a small period.

The Gallop Program had scored a great coup.

It was really a turning point in the ideas about pulsars.

So it became absolutely clear they

were rotating neutron stars.

There was no doubt about that.

Discovery of a pulsar in the Crab Nebula

was the confirmation that all of this was fitting together

and we understood it properly.

In 1999, the Subaru telescope at the summit

of Mauna Kea in Hawaii was aimed at the Crab Nebula.

Observe the object indicated in the middle.

Here it is in slow motion.

Something is twinkling, flashing unlike any

of the stars around it.

A pulsar.

And it is indeed a neutron star,

the remnant of a supernova.

The strange object predicted by Zwicky

had finally revealed itself.

So the pulsar is a neutron star.

It is the result of an exceptionally turbulent process.

A giant star, eight to 20 times the mass of our own sun,

reaches the end of its life.

It explodes as a supernova.

In the middle of it all, the atoms that make up its matter

are subjected to tremendously violent forces.

The orbits of particles disintegrate.

Electrons and protons fuse together creating neutrons

which rapidly condense in volume.

What finally emerges is a ball of neutrons

a mere 10 kilometers in diameter.

A neutron star is born.

The spinning energy of a giant star

more than eight times the volume of the sun

is now concentrated in this tiny object

10 kilometers in diameter.

So the neutron star revolves at fantastic speed.

And with its magnetic field,

the neutron star sends out pulses

of both radio waves and light.

The pulsar.

Professor Antony Hewish.

The discovery of pulsars for which you

played a decisive role is...

For role in the discover of the pulsar,

Hewish was awarded the Nobel Prize in Physics in 1974.

Further research revealed even more.

That the pulsar was responsible for a stupendous phenomenon

that went beyond anyone's imagination.

Stimulated by the discoveries of Hewish and Bell,

astronomers all over the world are using radio telescopes

to look for pulsars.

Parkes, Australia is home to a scientist known

as the world's number one pulsar hunter.

Richard Manchester.

He's been using the Parkes Observatory

to search for pulsars for the last four decades.

Parkes is a big telescope,

but by world standards, it's not huge.

There are radio telescopes in other parts of the world,

in Europe, in North America, which are bigger,

but we've found twice as many pulsars

as all of the rest of them put together.

And we're pretty proud of that.

The telescope is located in a natural setting

with more kangaroos than humans passing by.

There are almost no artificial radio sources nearby

to contaminate observations of the universe.

And given its location in the southern hemisphere,

it has a great view of the center of the Milky Way.

All this makes the Parkes Observatory the perfect place

for pulsar hunting.

Manchester also has a special device here.

It's housed in a white box as large

as a two-story bungalow positioned above the reflector.

This will be a rare look inside the box.

It takes 10 minutes to climb the 50 meter ladder

to the white box.

So this is the multibeam receiver.

It has 13 beams. You can just see the feed horns

through these panels.

Each of the 13 elements in the array

collects radio waves from a different direction.

A single receiver can cover

only one region of space at time.

But Manchester and his team have developed

an array of 13 receivers.

This multibeam receiver can observe 13 areas at once.

Once the multibeam was introduced,

pulsar identifications increased dramatically.

Manchester's team soon found more than 1,100 of them.

Thanks to the efforts of astronomers around the world

that number has reached roughly 2,000.

If we could see pulsars with our own eyes,

they would liberally populate the night sky.

It has become apparent that pulsars,

that is neutron stars, are quite common

throughout the universe.

Six, five, four, three,

we have a go for engine start, zero,

we have booster ignition...

in 1999 the Chandra X-Ray Observatory

was launched into Earth orbit.

You look out and this thing is so big...

Earth is constantly bombarded by x-rays

from distant parts of the universe.

Ground based scopes however,

are hindered from observing them

by the Earth's thick atmosphere.

That is the advantage of basing a telescope

in space where there is no such interference.

Chandra provides an excellent way

to observe the remnants of a supernova.

We'll look at a portion of the constellation Cassiopeia.

There's that famous W shape.

And off to one side is a supernova remnant

dubbed Cassiopeia A.

This is an image of Cassiopeia A taken with visible light

and with visible light that's about as good as it gets.

With Chandra however, it looks like this.

Gas clouds enveloping a neutron star

that is fiercely emitting x-radiation.

What does an analysis of their composition reveal?

This shows the presence of silicon.

The redder the area, the more there is.

The distribution indicates the extent

of the supernova explosion.

This is calcium.

And this is the distribution of iron.

Elements such as iron and silicon

are produced by supernovas.

Next, we'll use Chandra to search for a pulsar.

This nebula lies in the constellation Sagittarius.

A pulsar in its midst flashes with exceptional luminosity.

Ringed by gases, it's understandably

called the Bullseye pulsar.

This supernova remnant is in constellation Vela.

A pulsar has been detected here.

The nebula has an odd, tail-like protrusion.

This nebula has some pointy-ness to it.

It also has a pulsar, here.

Gases expelled by a supernova normally expand

outward in a spherical fashion.

But collisions with surrounding gases

have produced these strange angles.

This nebula has a long, long tail.

And at one tip, a pulsar.

The gas cloud is 4.2 light-years in length.

Measurements show that the pulsar itself

is not going anywhere.

So this long tail is a mystery.

This nebula has been called the Cosmic Hand.

The nebula almost looks like my hand here,

with the pulsar sitting here.

There are finger-like structures reaching up here.

There's a thumb-like region over here.

And we don't know why it looks like that.

I think most of us just smiled and looked at it

and said, well this isn't going to be easy to explain.

The pulsar is located at the heel of the palm.

The hand seems to be trying to grasp something.

It's a broad palm, 150 light-years across.

Truly this cosmic hand is an awesome sight.

Scientists find another structure

to be even more astonishing though,

the Crab Nebula.

Chandra can capture the x-rays it produces.

What appears now is a mushroom shape.

This is quite different from its optical image.

Koji Murai used the Chandra X-Ray Observatory

to study the Crab Nebula.

He observed it continuously over a five month period.

As he did so, he saw an awesome phenomenon

he had no expectation of seeing.

What attracted his attention was

the ring of gas in the center.

He imaged it at three week intervals

and combined the results.

It had moved.

The ring is one light-year across.

That's 60 thousand times the distance

from the Earth to the Sun.

Yet on that gigantic scale, the ring suddenly enlarged.

A ring expanding at half the speed of light.

Why is the gas ring expanding at all?

One scientist has tried to solve the mystery

of this pulsar phenomenon by means

of computer simulations.

Shinpei Shibata thinks that the reason the ring

is enlarging so fast is that the pulsar

at its center carries an exceptionally

powerful magnetic charge.

Shibata and his associates used a supercomputer

at the National Astronomical Observatory of Japan

to simulate the pulsars environment.

Then they set a pulsar, meaning a powerful magnet,

spinning in that environment.

That yields a vast amount of electrical energy,

which in turn produces a huge quantity of particles.

The particles are spun off by the rotating pulsar

and flung out toward the periphery.

The speed of these ejected particles has been calculated.

It's 99.999999999999% of the speed of light.

The pulsar wind blasts out at light speed.

At those fierce speeds, the pulsar wind

pushes surrounding gases outward.

This rendering of the pulsar is based

on the latest research by Shibata.

And so we take an imaginary journey

into deep space to the Crab Nebula.

We plunge into the nebula

greeted by a fearsome particle storm

with winds reaching half the speed of light.

It's still one light-year to the pulsar.

We can see the ripples spreading out.

The pulsar is now a billion kilometers away.

And now we can see the lighthouse effect.

The source of that flashing light is the pulsar.

Finally, the pulsar itself, a shimmering ball of neutrons

just 10 kilometers in diameter.

It's gravitational force is so tremendous,

all bumps and dips are leveled out.

The surface gleams like a mirror.

It even reflects the spaceship.

It's simply amazing that such an object exists.

Seen close up, the pulsar can only be called

a wonder of the universe.

The latest research has revealed

that pulsars are also a source of a certain element

of particular interest to humans.

It happens during the most violent explosions

known to occur in outer space.

Thomas Janka and Shinya Wanajo are pursuing this matter

by creating computer simulations

of violent collisions between two neutron stars.

First Janka creates the neutron star collisions.

The two neutron stars orbit each other

in very close distance.

You can see that the distance between the two neutron stars

is a bit smaller already than the diameter.

And then the two neutron stars actually finally

approach each other with violence and merge

into one big blob of metal.

As soon as they collide and merge,

the two neutron stars are enshrouded

in a misty shell of particles.

These are neutrons shed by the neutron stars.

And eject in the end at large distances

radiates a gamma ray burst which we see

as the brightest flash observable in the universe.

The two neutron stars approach one another rapidly.

Finally, at 30% of the speed of light,

they collide and merge.

At that point, a huge quantity of neutrons is released,

along with a huge amount of energy

causing a gigantic explosion.

The biggest explosion in the universe, a gamma ray burst.

Wanajo believes that this is when various forms

of matter emerge from the cloud of neutrons

released by the explosion.

They say that it is actually rather easy

to envision the phenomenon of neutrons

producing other matter.

The neutrons that spread about

at the moment of impact carry a neutral charge.

So they can combine with other matter easily,

they offer no resistance.

As more and more neutrons attach to a given nucleus,

the nucleus grows larger and larger.

Wanajo calculated the type and quantity

of elements created at that stage.

Consider what happens during the first 0.3 seconds

after the explosion.

The line extended towards the upper right of the graph

indicates the volume of neutrons combining together.

Heavy elements appear in a flash.

0.01 seconds after the blast.

The neutrons as they combine,

begin to form heavier nuclei.

Large quantities of neutrons whiz about,

creating elements such as iron and silver.

At 0.3 seconds after the explosion,

more neutrons get added.

When they reach a certain mass,

the nuclei stabilize.

So the collision scatters vast quantities

of neutrons about.

And in very short order, they produce gold.

So how much gold does the collision

of those two neutron star produce?

And how does it get scattered about?

This is a computer graphic rendering

based on those calculations.

All those neutrons have produced a vast quantity of gold

which is then dispersed through space.

The quantity of gold produced at this time

is equivalent to triple the mass of planet Earth.

Wanajo and Janka say that if one goes back far enough,

one could trace Earth's gold also

to collisions between neutron stars.

At least the neutron star merges seem

to be a good candidate for the most,

for the main produces for the origin of most

of the very heavy elements, like uranium and gold.

Collisions between neutron stars,

happening far away, and long ago.

The gold we ourselves handle was created

by the largest collisions in the universe.

During the filming of the work done

by pulsar hunter Richard Manchester,

an unexpected discovery was made.

Coffee cup in hand, he begins his observations for the day.

Manchester knows a number of regions

where pulsars are relatively likely to be found.

He targets one of them.

For 30 minutes he directs the 64 meter antenna

at one star in particular.

That's when it happened.

Oh, oh, oh! Oh look at that.

Yeah, yeah, yeah that's a binary.

Well now, let me just, I turned off...

Is this binary star the kind that produces gold?

There is a...

There's a curvature There's a curvature, yeah.

Very good! Yeah, yeah

That could be an interesting source,

what's the period?

One two three milliseconds.

123, so it could even be a double neutron star.

So that's pretty amazing, wow.

Not a bad haul Pretty good.

And we only know of ten or twelve of these systems

out of the 2,000 pulsars that we know about

and so finding another one would be very exciting.

The two neutron stars in a binary system

will eventually, it is thought,

approach each other and collide.

Along with one of the greatest explosions in the universe,

the result will be an increase in the amount

of gold in existence.

An increase equivalent to several times the mass

of our entire planet.

Today as well, pulses from afar are reaching our planet.

Pulses that led to the discovery of neutron stars,

spectacular celestial bodies.

The pulsating neutron star, or pulsar,

is the strangest object in the universe.

And one deeply associated with the creation of matter.

It will continue to challenge humanities vision and

intelligence for many years to come.