How the Universe Works

Narrator: Stars... they're big, they're hot,

and they are everywhere.

Stars rule the universe.

Our destiny is linked to the destiny of stars.

Narrator: Born in violence, dying in epic explosions.

They fill the universe with stardust,

the building blocks of life.

Every atom in your body

was produced inside the fiery core of a star.

Narrator: Stars are what make our universe work.

All life begins here.

The night sky is packed with stars.

On a clear night in the country, if you're lucky,

you can see maybe 3,000 stars.

But that's just the tip of a vast cosmic iceberg.

In our galaxy alone, there are over 100 billion stars.

And, in fact, there are over 100 billion galaxies

in the observable universe.

There are more stars than there are specks of sand on earth.

Narrator: Every star is powerful,

creating the basic matter

for everything in the universe...

Including us.

Most are so far away, we know little about them.

But there is one star that's really close,

and virtually everything we know about stars,

we've learned from that neighbor.

The sunlight from our sun that bathes us

and warms us every day is nothing but starlight

because our sun is nothing but a star like all the rest.

Narrator: Seen from earth,

our sun is a blinding ball of light.

But take away the glare,

and one of the most powerful objects in the universe

appears in our own backyard.

It's a ball of superheated gas that's been lighting

our solar system for 4.6 billion years

and dominates all life on earth.

The sun is 93 million miles away.

And that means, in actuality, it's immense.

You could fit a million earths inside the sun.

Narrator: It's nearly a million miles in diameter,

yet our sun is tiny

compared to the really big stars out there.

Eta carinae... over five million times larger than our sun.

Betelgeuse... 300 times larger than eta carinae.

If it was our sun, it would reach as far out as Jupiter.

And then there's this monster... v.Y. Canis majoris,

the largest star ever discovered.

A billion times bigger than our sun.

Stars burn in different colors, from red to yellow to blue.

Some live alone.

Others in pairs, orbiting each other...

And coming together in huge galaxies...

Entire cities made up of billions of stars.

Each star is a one of a kind.

But they all start life in the same way...

As clouds of dust and gas called nebulas.

Many billions of miles across,

they drift through space, forming spectacular shapes.

The flame nebula.

The horsehead nebula.

The Orion nebula.

Each nebula is a star nursery

where millions of new stars are being born.

But this birth is hidden from view.

Dr. Thaller: Some of the more dramatic parts of a nebula.

Are not the beautiful glowing gas

that you see but the dark parts.

The dark parts have areas of dense gas and dust,

and that's where the real action is happening

in terms of star formation.

The dust clouds are so thick,

regular telescopes can't see inside.

Dr. Thaller: There's nothing more important to us than stars,

but for a long time,

the way they formed was a complete mystery.

We couldn't observe them. Imagine that.

We could not see the first moments of a star at all.

Narrator: Until 2004 when NASA launched the spitzer space telescope.

Man: And liftoff.

Seeking hidden secrets

and the evolution of our universe.

Spitzer is an infrared telescope.

It only sees heat.

Heat passes through the thick dust of the nebulas,

allowing spitzer to see new stars coming to life inside.

These remarkable pictures

capture the earliest moments in a star's life

as pockets of hydrogen gas begin to heat up.

Dr. Thaller: Any little bit of gas and dust is glowing.

Areas that were entirely dark now became bright.

We can actually see the very earliest parts

of star formation.

All you need to make a star is hydrogen, gravity, and time.

Gravity pulls the dust and gas into a giant swirling vortex.

Dr. Thaller: Gravity brings matter together.

And when you bring matter together

and you squeeze things into smaller spaces,

they necessarily heat up.

It's a simple law of chemistry.

You compress something, you drive the temperature up.

Narrator: Over hundreds of thousands of years,

the cloud gets thicker and forms a giant spinning disk

bigger than our entire solar system.

At its center, gravity crushes the gas

into a superdense, super-hot ball.

Pressure builds until huge jets of gas

burst out from the center.

Dr. Thaller: That really shows you.

How violent a process star formation is.

These jets are many light-years across.

Something is literally accelerating material very fast

across unimaginable distances.

Narrator: Gravity keeps the pressure on,

sucking in gas and dust particles

that smash into each other, generating more and more heat.

Over the next half a million years,

the young star gets smaller, brighter, and hotter.

Temperatures at its core reach 15 million degrees.

Only at that mind-boggling temperature

can atoms of gas begin to fuse together,

releasing massive amounts of energy.

And just like that, a star is born.

It will shine for millions,

even billions,

or perhaps even trillions of years.

Narrator: Stars produce massive amounts of heat and light.

Over billions of years.

But that takes fuel and lots of it.

Until the early 20th century,

no one had any idea what this fuel was.

The greatest problem facing physics

at the turn of the last century was,

what drives the energy of stars?

All you had to do was look outside

and realize there was a huge gaping hole

in our understanding.

To solve the secret of the stars,

we needed a new engine.

We needed a fabulous source of energy

that could drive a star for billions of years at a time.

Narrator: And it took a genius to discover it...

Albert Einstein.

His theories proved

that stars could tap into the energy inside atoms.

Kaku: The secret of the stars is Einstein's equation e=mc2.

In some sense, matter, which makes up our body,

is concentrated energy, condensed energy...

Energy that has condensed into the atoms

that make up our universe.

Narrator: Einstein showed that it's possible.

To release this energy by smashing atoms together.

It's called fusion, the same force that powers stars.

It's astonishing to realize that the physics

of the very small subatomic particle physics

determines the structure and nature of stars.

Narrator: From Einstein's theories,

we learned how to release the energy inside an atom.

Now science is trying to simulate

a star's energy source

to control the power of fusion in a lab.

Inside this laboratory near Oxford, England,

there's an 80,000-pound machine.

Every day, Andy kirk and his team

transform it into a star...

On earth.

Dr. Kirk: This machine is called a tokamak.

It's effectively a large magnetic bottle...

A cage to hold a very hot plasma.

We're able to re-create the conditions within a star.

Narrator: Inside the tokamak,

hydrogen atoms naturally repel each other.

To smash hydrogen atoms together,

the tokamak heats them to more than 300 million degrees.

At these temperatures, the energized hydrogen atoms

are moving so fast,

they can't avoid smashing into each other.

If you heat it up, heat is motion.

And the motion of hot particles

will be enough to overcome the repulsive force.

Woman: All personnel, be prepared to leave.

Come off the machine area.

Narrator: When everything goes right,

the result is the single best power plant in the universe...

Nuclear fusion.

Traveling at 1,000 miles a second,

the hydrogen atoms smash into each other and fuse...

Creating a new element... helium...

And a small amount of pure energy.

Kaku: The hydrogen gas weighs slightly more than the helium.

You lost mass in the process of burning.

That mass that you lost, the missing mass,

turns into energy.

Narrator: The tokamak can only maintain fusion.

For a fraction of a second.

But inside a real star,

fusion continues for billions of years.

The reason is simple... size.

Kaku: The engine which drives a star is gravity.