The Universe

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."

They are the freaks of the cosmos--

pulsars and quasars.

So strange, their very existence seems impossible.

They must be titanic, absolute monsters.

What makes them shine with the light of a billion suns,

rotate faster than the blink of an eye,

or bang out cosmic rhythms

with the drummer from The Grateful Dead?

Once all of these things started to come my way

I realized that, you know, the universe was singing.

But it's a tune bizarre beyond imagination,

with pulsars and quasars

the superstars of an astronomical sideshow

found only in the strangest sectors of the universe.

In 1967, scientists on planet Earth made a startling discovery.

Something, someone, was sending us signals through space.

Were aliens trying to send us a message?

When pulsars were first discovered, they blew us away.

Something in the night sky was turning on and off.

How could something in nature do that?

And so we actually called them LGM objects.

That stood for little green men.

Astronomers in England detected the signals

using a primitive radio telescope,

a massive array of poles and wires stretched out over four acres of land.

The first of the signals

was not just an isolated peak in the radio noise.

It was a regular blip, precisely repeating every 1.3 seconds.

Within a year, though, scientists realized

aliens were not behind the regular signals.

Instead, they came from rapidly rotating stars.

"Pulsar" became the catchy name for the new phenomenon,

short for pulsating star.

A pulsar seems to blink on and off

because the rotating star is sending out beams of energy

from its magnetic field,

which is not aligned with its axis of rotation.

We see the beam as a flash of light when it passes across our field of view.

The beam coming out of a pulsar works a lot like this emergency beacon.

Now take a look at how it flashes.

It's not just blinking on and off.

Inside the housing, the beacon has a rotating reflector

that sweeps the light around 360 degrees.

As long as we have line of sight with the beam,

it sweeps by us every time it goes around.

But it looks like it's flashing on and off.

A rotating pulsar looks like it is flashing on and off for the same reason.

But a pulsar isn't just any kind of rotating star.

It's a rotating neutron star,

an exotic object created when a big, massive star ends its life in a supernova.

Astrophysicist Pat Slane has a fascinating way to show us

what's left over after the supernova,

when the pressure of the star's remaining core

can no longer fight against the force of gravity.

What I'm going to demonstrate here

is what happens when we remove the air

from the interior of this 55-gallon drum

and let the atmosphere of the Earth, the weight of the air, crush it.

This is similar to what happens

at the interior of a massive star late in its life.

When it loses its pressure support,

the star collapses, and there's a supernova explosion.

The crushed stellar remnant becomes the neutron star

with a mass 1.4 times our Sun

reduced to a sphere the size of Manhattan.

It is one of the most bizarre objects in nature.

You have to understand that a neutron star

is matter barely holding up before it collapses into a black hole.

The gravity is so strong

that it has crushed electrons into the nucleus of an atom

and made neutrons.

It's amazing.

If you take something like a sugar cube, for example,

about a cubic centimeter.

If this sugar cube were made of neutron star material,

it would weigh close to a billion tons.

Think of it as something like 8,000 aircraft carriers

in something that size, incredibly dense objects.

The newly created neutron star can't help having a high-speed spin.

All stars that we know about are already rotating,

so when a massive star compresses into a neutron star,

the rotation is compressed also.

It's just like an ice skater.

When an ice skater spins and she pulls her arms in,

she spins faster.

The spinning neutron star is a massive natural electric generator.

Its spin creates a powerful magnetic field.

The magnetic force grabs onto electrons and other atomic particles

and flings them into space at high speeds.

High-speed particles always emit radiation,

and in pulsars, they're coming out in beams.

These are the pulses we see, but we see them

only when the beams are pointed in our direction.

How many pulsars are known?

It's something over 1,800, and the number is growing rapidly,

because we continue to discover new pulsars all the time.

But the number of pulsars that exist--

and these are all found in our galaxy, the Milky Way--

Is many, many times larger than that,

because the beams, that are seen in radio primarily, are very small,

and so we only see a tiny fraction of all the pulsars that are out there.

But each pulsar has a completely different rotational speed.

The slowest rotates once every 9.437 seconds,

and the fastest goes around 716 times every second.

If we stood on its surface,

we'd be going more than 97 million miles per hour.

That's about 10 million times faster than we travel on Earth.

Every pulsar has an absolutely unique spin.

It goes around at a given rate,

and that's just like a fingerprint for an individual.

So if you know what that characteristic spin is,

then you know what that pulsar is.

Since all pulsars have their own signatures,

you can use them as tools to determine your location in space,

an idea that has been used by NASA.

Some of the spacecraft we've sent into the outer parts of the solar system,

like Pioneer and Voyager, have had maps of space

which show our solar system's location

relative to the locations of a bunch of pulsars.

The pulsars in space can be used to locate the Earth

in the same way that our GPS devices use multiple satellites

to locate a position on the ground.

It's hoped one day

another race of space travelers will find one of the spacecraft

and read the map to learn where it came from.

A sufficiently intelligent alien could figure out where we are

by measuring all these same pulsars

and figuring out where we are in relation to them,

because each pulsar has a unique period.

The unique spin of each pulsar

also makes them super-accurate astronomical clocks,

keeping better time than the best atomic clocks here on Earth.

Pulsars are so accurate because they're nature's ultimate flywheel.

This is an ordinary bicycle tire mounted on a repair rack

here in this bicycle shop.

And this wheel is very much like a pulsar.

Let's give it a spin.

So you see the wheel is rotating very smoothly.

There's very little to slow it down.

Now, for a pulsar in space, there's almost nothing to slow it down.

Now notice that the wheel is rotating about a couple times a second.

That's the average speed of rotation for an average pulsar.

Now, of course, this wheel is only a few feet across,

whereas a real pulsar is spinning at the same speed,

but it's the size of Manhattan.

But nothing is forever,

and even pulsars slow down over time,

although they do it very slowly.

The same bicycle wheel that illustrates the pulsar's spin

also demonstrates what makes it slow down.

Pulsars convert rotational energy into radiation,

and in the process, they have to slow down.

Let's see how it works with the bicycle wheel.

Now, the wheel is moving pretty quickly.

If I put my hand to the rim,

I can convert rotational energy to heat energy in my fingers.

Ouch.

Now the wheel has slowed down.

In a real pulsar, it would be more like the action of a feather than my hand,

because pulsars lose energy very, very slowly.

A pulsar, spinning once every second,

may slow down by about

only three hundreths of a second in a million years.

Occasionally, though, a pulsar may actually speed up slightly

in a phenomenon linked to a neutron star's crust,

a layer of matter 10 billion times stronger than steel,

and yet subject to "starquakes."

Neutron stars are not solids all the way through.

They have a crust.

And that crust is incredibly strong.

But there are forces within the neutron star

that can occasionally cause the crust to crack.

When it cracks, the whole neutron star readjusts itself,

and it produces a change in the rotation of the neutron star.

We call it a glitch.

The crust is cracked.

There has been a starquake on this neutron star.

Though the strange world of pulsars

includes intriguing events like glitches and starquakes,

you'd hardly know it from the tiny blinks seen

when they're captured by telescopes.

But what happens when pulsars

are hurling deadly radiation into cosmic clouds

after their parent stars have ripped holes in the galaxy

with their massive explosions in space?

What will their impact be on any living beings in their path?

The deadly explosions of supernovas are endlessly fascinating.

They are the violent screams of aging stars,

outraged at having to grow old.

The powerful blasts would do more than kill any living beings in their path.

A supernova would wipe out all traces of any civilization

on a planet in orbit around the exploding star.

The galaxy is full