All language subtitles for How the Universe Works - 3X01 Journey from the Center of the Sun

The sun, our nuclear powerhouse.

Our star, its light powers our world...and us.

Without light, we would not be alive.

Starting deep inside the sun,

We follow the brutal journey

Of a single, tiny package of light -- A photon.

The ride that any photon takes
to get to my eyes

When i look up at the sun
is an amazing one.

From its ancient birth
in the sun's core

To its escape from the surface.

The light reaching me
from the sun

Was produced before there
was even human civilization.

It's an incredible idea.

Join our photon

On its incredible
million-Year journey

Through the most hostile
environment in the solar system

To bring light and life
to earth.

The universe,
home to billions of galaxies...

...each made
of billions of stars.

And, in an unremarkable corner
of our galaxy, the milky way,

Lies the sun,
our closest star...

...a dazzling sphere
of intense light,

Too bright for the naked eye.

But strip away that glare,
and the sun transforms

Into a giant ball

Of super heated gas
dominating our cosmic stage.

The sun is really
the star of the show.

The sun is the parent
of the whole solar system.

It provides its children,
the planets,

With everything they need.

We depend on the sun for energy,
for light, for warmth.

We would not exist
without the sun.

The sun
generates heat and light,

The energy source
for all life on earth.

All of the energy
that my body uses,

Literally what i'm doing
to talk to you right now,

Came from the sun.

The sun truly is the creator
of all of the life around us.

The sun
is a constantly exploding

Nuclear bomb,
violent and essential.

Our entire existence
is powered by the energy

Emitted in those
nuclear reactions in the sun.

We are here because of the light
from the sun.

We are here because
of those nuclear reactions,

And no aspect of our existence
could persist

If it wasn't there.

Light is
one of the basic building blocks

Of the universe.

I find light to be probably

The most amazing thing
in the universe.

It's so important in everything.

I mean, it's everything.
It's everywhere.

So, it's such a fundamental part
of everything that exists.

Fundamental and fast.

The fastest thing
in the cosmos...

...traveling at 186,000 miles
per second.

The sun is about
93 million miles away from us.

So, going at 186,000 miles
per second,

That's about eight minutes.

But those eight minutes

Are just the brief last leg
of its incredible journey.

It may have taken the light
as much as a million years

To escape from
the sun's raging interior...

...which means the light
we're seeing right now

Was created long before

Our ancestors
left the plains of africa.

When i first learned this fact,

I was already
a practicing scientist.

I had never really
thought about that,

And on first glance,
it just blew me away.

Right now the light
reaching me from the sun

Was produced before there
was even human civilization.

And yet, the minute it gets
to the surface of the sun,

It races away and is here
eight minutes after that.

It's an incredible idea.

The ride that any photon takes
to get to my eyes

When i look up at the sun
is an amazing one.

That ride starts
deep in the belly of our star.

If we could open up the sun,

We'd see layers
of dense hydrogen gas

Hundreds of thousands
of miles deep.

And at its center, the core,
the sun gives birth to light...

...forged in one of the most
violent reactions

In the universe, nuclear fusion.

The specific nuclear reaction
that powers the sun is fusion,

Fusion of hydrogen into helium.

You take two hydrogen atoms,
you ram them together,

And what's left over
is a helium atom.

It sounds simple enough,

But it's not.

It's actually hard
to get two atoms to fuse.

Two photons
have the same charge.

They're both positively charged.
They want to repel each other.

Protons don't like
to get close together.

They have to come together
with a huge amount

Of energy or velocity

To get close enough
to begin to fuse,

And that's very, very rare.

To force protons together

Takes immense amounts
of heat and pressure...

...generated by
the invisible hand of gravity.

The sun contains 99.8%
of all the matter

In the solar system.

That's a lot of mass.

All that mass
pulls the sun together

With unimaginable
gravitational force.

With gravity
crushing things down,

Things get close enough together
and nuclear fusion happens.

In this nuclear compactor,

Hydrogen atoms slam together

100 million quadrillion
quadrillion times each second.

Some of these collisions
are so powerful that atoms fuse,

Releasing energy.

When the protons
come together to bind together,

They lose a little bit of mass,

And that mass
gets converted into energy.

And every second of every day,

About five million tons of stuff
is being converted to energy.

It's amazing.

Each collision
creates a tiny burst of energy,

A packet of light impossibly
small and incredibly powerful.

Somehow, our photon
will deliver its energy to earth

Where it will power the planet
and make life possible.

But right now it's nothing like
the light we see.

It has massive amounts
of energy, and it's deadly.

The light we see
from our star is old...

much older
than the eight minutes it takes

To get from the sun to earth.

That short leap across space is
the end of a long, hard journey

That starts deep inside our sun.

When we look at the sun,

We say, "how beautiful,
how elegant, and how simple."

Light is formed in the sun,

And it shines
and lights up our world.

Well, not so fast.

It's actually very complex.

The journey starts

In the immense heat
of the sun's core.

Crushed together
by the sun's enormous gravity,

Atoms smash into each other
and fuse...

...releasing a tiny packet
of energy, photon of light...

...far smaller
than an atom with no mass.

Photons travel
faster than anything else,

And they never stop moving.

Photons don't just come
from the core of stars.

So, where does light come from?

The short answer is,
matter makes it,

And the amount of light
that it creates

Depends on its temperature.

Every piece of matter
in the universe

Above absolute zero degrees

Produces light,
including humans.

We humans
are emitting light all the time

Because we're alive, we're warm,
we're not at a zero temperature.

So, in fact we are emitting
infrared radiation,

Often called heat radiation.

But all matter emits light.

Even someone as cool as me,
i'm creating light right now.

The light we see

Can be split
into the colors of the rainbow.

Each color is photons of light

With slightly different amounts
of energy.

And what we can see

Is only a fraction
of the light spectrum.

Our eyes are actually
imperfect detectors.

We know about visible light,

The type of light
that our eyes are sensitive to,

But that's only a small range
of energies.

Light comes at higher and lower
energies than we can detect.

Using special cameras,

We can see the infrared light
that humans emit.

This infrared light

Has less energy
than the visible light we see.

Some light is too energetic
to see,

Like ultraviolets,
x-Rays, and gamma rays.

The vast, hot sun
generates all forms of light.

But in the nuclear furnace
of the sun's core,

Every photon starts out
as a gamma ray,

The most energetic form
of light in the universe.

And when
a nuclear reaction happens,

It emits
an amazing amount of energy,

The energy much, much bigger
than visible light --

Gamma rays, we call them.

Literally almost a million times

Or at least 10,000 times
the energy of the light we see.

Gamma rays
can transform and even kill.

There's a reason why gamma rays

Turned bruce banner
into the hulk.

Gamma rays are a very dangerous
form of light.

They can travel into your body

And when they interact
with the matter,

They can break apart atoms.

Fortunately for us,

Our gamma-Ray photon can't
head straight out of the sun.

If the sun
were not this hot ball of gas,

Then upon being created,

A photon would immediately
escape from the sun

And it would be
a gamma-Ray photon,

A very energetic photon,
not very good for life on earth.

After its birth as a gamma ray,

Our photon starts
to race out from the sun's core

At the speed of light.

But it encounters an obstacle
course of epic proportions.

A journey
that should take seconds

Slows to a cosmic crawl.

It takes on average
about 100,000 years

For a photon to make it
from the middle of the sun,

Where it was created,
to the outermost edge,

Where it gets emitted
into space -- 100,000 years.

If it had traveled
in a straight line unimpeded,

It would have taken two seconds.

What could possibly
slow a photon

Moving at the speed of light?

Something slams on the brakes --
Huge, hot, dense.

So powerful,
it doesn't just slow light,

It transforms it.

In the sun's core,

Nuclear fusion releases
a tiny bundle of energy...

...a photon of light.

It races outwards
at 186,000 miles per second.

At that speed,
it should take two seconds

To travel through the
sun's interior to the surface.

But something turns seconds
into an eternity.

The sun is so dense

That to get through all
of the different layers of gas,

This poor little piece of light
takes hundreds of thousands,

If not a million years,
to get to the surface.

So,
when you're looking at the sun,

You're looking at the light

Emitted from reactions
a million years ago.

Our newborn photon

Leaves the core
at the speed of light

Only to run smack
into a dense soup

Of hydrogen atoms,
a photon's nightmare,

That stretches
for over 400,000 miles.

If you're a photon
born in the center of the sun,

You have a heck of a journey
ahead of you.

It's actually pretty hard

For light generated in
the core of the sun to get out

Because there's a lot of sun
in the way,

And it's extremely dense.

The radiation zone
surrounds the core of the sun.

The zone is made
of hydrogen gas,

But not a gas as we think of it.

The sheer weight
of all the material above

Compresses the radiation zone
until it's denser than lead

And nearly impossible
to pass through.

A photon produced
in the center of the sun

Knows where it wants to go.

It wants to go to the edge
where it's cool,

And it wants to get out.

But it's got 400,000 miles

Of all these opaque gases
blocking its way.

These gases aren't
just dense -- They're hot,

Superheated to over 12 1/2
million degrees fahrenheit.

The gas in the radiation zone

Is transformed into
what scientists call plasma.

Plasma is the fourth state
of matter.

Atoms in normal matter have a
nucleus with orbiting electrons.

In plasma, the atoms
have been torn apart

And the electrons ripped away.

Here on earth, we're familiar
with the three main states

Of matter
that we're taught in school --

Solids, liquids, and gases.

You know, we have the atmosphere
as a gas, the oceans are water,

The ground
that i stand on is solid.

But in fact,
most of the universe,

Including stars,
consists of plasma.

Compared to
the rest of the universe,

Earth is a calm place.

Most of the time,

It's not hot or violent enough
here to create plasma.

The best place to witness
the power of plasma on earth

Is inside a lightning strike.

Temperatures inside a bolt can
reach 53,000 degrees fahrenheit,

Enough to momentarily
rip a few atoms apart.

The plasma lasts an instant.

Then the electrons rebind
and it's gone.

But in our massive sun,

The plasma
lasts for billions of years

And makes up

The entire 200,000-Mile-Deep
radiation zone.

Worse for our photon,

The plasma is electrically
charged, forming a cosmic trap.

And a plasma
is opaque to radiation

Because light
interacts much more strongly

With electronically charged
objects

Than with neutral objects.

So, when you
have a neutral atom,

Light in general can pass by.

But when you separated
the charges

And you have positive
and negative charges

Located everywhere,
the light can't make it through.

Our photon,
in the form of a gamma ray,

Has entered the radiation zone

And smashed
into a charged plasma particle.

For a fraction of a second,

The particle absorbs the photon,
then spits it back out,

And the photon collides
with another particle.

Every time it goes
a little bit of a distance,

It basically slams into an atom,

Is absorbed and readmitted
in some random direction.

So, instead of just flying out,

It's bouncing around countless,
countless, countless times

Until finally, it reaches
the edge of the star.

It's an atomic game
of basketball

With a court
representing the radiation zone.

The players stand in
for the particles and the plasma

And the ball is the photon.

So, the basketball

Is being thrown from one player
to another seemingly randomly.

It's not making a lot
of progress down the court,

But it is gradually
making progress.

Gradually over time, it is going

From the hotter parts
of the core outward

Toward cooler temperatures.

That's where it wants to get.

It's a random-Looking process,

But it's directed in
a certain direction with time.

The photon wants
to go straight up the court --

Its quickest route --

But is bounced and thrown
around the radiation zone,

Slowing to a crawl.

This bruising process
transforms the photon.

When a photon,
a little packet of light,

Is created
in the center of the star,

It's actually a gamma ray,
super high energy bit of light.

And it can't go very far
because as soon as it does,

Boom, it hits another atom
and gets absorbed.

Every time it does this,

It loses
a little bit of that energy.

Over several
hundred thousand years,

Sometimes even a million,
the photon keeps bouncing

Through the dense
radiation zone.

Each collision saps
a tiny bit of energy,

Transforming it
from a lethal gamma-Ray photon

To a lower energy x-Ray.

Nearly a million years
after its creation in the core,

The photon has made it
through the radiation zone,

But its quest to escape
is not over yet.

It's about to hitch a wild ride

On the sun's ferocious
internal roller coaster...

...a place so violent,
it makes the sun roar.

A photon,
nature's energy-Delivery system,

Has spent up to a million years

In the maze
of the sun's interior

On its journey toward the earth.

The photon has fought its way
through 3/4 of the sun's radius.

Battered and sapped of energy,

It is morphed from
a deadly gamma ray to an x-Ray.

But now it enters the mysterious
boiling layer of the sun,

The convection zone.

The convection zone
lies between the radiation zone

And the sun's surface
and is 125,000 miles deep.

We can't see
the convection zone directly.

This region of the sun is still
opaque to our telescopes,

But we can hear it.

Nasa's solar dynamics
observatory listens to the sun.

The sound it picks up
is too deep for humans to hear,

But if you speed up
40 days' recording

Into a few seconds,
this is what you get.

It's the sound of chaos.

Since we can't see into the sun,

Its sound
is vital to scientists.

When a gun fires, the bullet
rushes out and smashes into air,

Creating waves of turbulence.

When we hear the gun firing,

These waves
vibrate our eardrums.

What we see here is sound.

The sun works the same way
on a much larger scale.

When we see these waves
moving across,

What we're looking at
is when material moves up

From inside the sun
and it makes noise.

It just, like,
ran into a surface.

It just ran into a wall,
and it generates sound.

And we see that sound
moving all around the sun.

Sound waves
crashing through the plasma

Create ripples
in the sun's surface.

And all we see
are these ripples.

Those are the actual sound waves
of the sun,

And they move
around the entire sun.

They move down inside the sun.

They move back up
to the surface.

By tracking the sound,

Scientists
can see the invisible.

They pick up sound waves

Smashing
against the sun's surface

And resonating
throughout the solar interior...

...revealing a violent,
boiling convection zone.

The sun can be said
to be ringing.

You have this hot gas rising.

You have cool gas falling.

You have all this turbulence.

You have so much action going on
that it causes the sun to ring.

Columns of gases rise and fall,

Churned by heat from below.

If you look at water boiling,

Bubbles of gas or water are
rising up because they're hot.

And then they cool off,
and then they sink back down.

And if you look
at a pot of boiling water,

That's the same phenomena
that's going on the sun,

But with hot plasma
instead of water.

At the bottom
of the convection zone,

Photons smash
into atoms in the plasma,

Heating them to a boil.

But this time, the photons
are absorbed by the atoms.

The hot atoms ride
the boiling current to the top,

Dragging the photons with them.

So, it's almost like
this conveyor belt of material.

Photons are actually
hitchhiking a ride on the atoms

That are traveling upward
through this heat transfer.

So, it's a much easier ride
in the convection layer

Than it is
in the radiation zone.

It's as if our photon
were now in the hands

Of a single player
making a fast break.

In the convection
layer, it's a direct path.

One player can actually hold on
to this basketball or photon

For a lot longer
in a direct path.

By not passing,

The atom takes the ball
quickly up the court.

The photon's journey
through the convection zone

Takes just one week.

But in that time,
the photon is transformed.

The bottom
of the convection zone

Is around
360,000 degrees fahrenheit.

The top -- Just 10,000.

So, as the photon rises up,
it cools, losing energy,

Changing from an energetic x-Ray
to visible light.

So, it starts
as a high-Energy x-Ray

At the bottom of the convection
zone, moves its way up,

It loses a little bit
of that energy.

By the time it leaves there,

It's closer to the kind of light
that we see,

Which is visible light.

At the top
of the convection zone,

The atom releases the photon,

Which shoots out
as visible light.

This cools the atoms,

Which fall back down
to absorb more photons,

Heat up, and rise again.

The photon is now
just below the sun's surface.

But the churning convection zone
unleashes another force --

A force that powers huge storms,

Detonates bombs, and threatens
to stop light's escape.

In the sun's core,

Nuclear fusion has created
a photon, a packet of light.

It has battled
through the radiation zone,

Been dragged up
through the convection zone

On columns of hot plasma,
hurdling towards its escape.

On this million-Year journey,

The photon has changed from
an invisible deadly gamma ray

To the kind of life-Giving light
we see here on earth.

Finally,
it has reached the surface --

The visible shell of the sun,
the photosphere.

The photosphere,

Which is basically
the visible part of the sun,

Or the surface, is what we see
when we look up at the sun.

We're seeing visible light
coming from that very layer,

The photosphere.

The ball
of blinding light we perceive

Hides a spectacular
and savage world.

The sun from a distance
looks quiet and serene,

But if you take a close-Up
of the surface of the sun,

You see that it's churning
with activity.

It's beautiful and
terrifying at the same time --

Huge storms of material
bubbling and boiling.

It looks like a witch's brew,

Except the bubbles
in the witch's brew

Are larger
than the size of the earth.

The surface of the sun
is a turbulent barrier.

And once again,
our photon gets taken hostage.

At kitt peak observatory
in arizona,

Solar astronomer matt penn
studies this solar surface

To discover how photons of light
get trapped.

There's a bunch of cirrus today,

But hopefully,
we'll get some data.

Using
the mcmath-Pierce telescope,

He focuses the sun's light to
scan the photosphere in detail.

So, what we've got
are a few small sun spots

On a disc of the sun.

We've got two sun spots,
two large ones.

They're heading off
to the edge of the sun,

To the limb of the sun.

But they're all accompanied
by a smaller sun spots,

Groups of smaller ones,
following them.

Sun spots mark areas
where light is trapped.

So, a sun spot forms a dark spot

By removing energy
from that part of the sun.

It's blocking the convective
flows that transport the heat

And the light
from inside the sun to space.

So, what we see then
is a cooler region

That appears dark to us.

A powerful force stops
our photon dead in its tracks,

Preventing its light and energy
from leaving the sun's surface.

That force is magnetism.

Sun spots take shape
where intense magnetism

From deep inside the sun blasts
up through the photosphere.

The magnetic fields
are so strong that it actually

Stops the convective motion
of hot inner material

From flowing to the surface.

So, you actually get
what looks like a cool spot

On the surface of the sun.

They can be huge,

The largest over 10 times
the size of earth.

The magnetism
that generates these sun spots

Forms field lines
covering the sun.

On our solid earth,
the whole planet

Rotates together,
including its magnetic field.

But the sun
is a big ball of gas,

And the same rules don't apply.

You see, there's nothing solid
about the sun.

It's a big ball of gas.

It turns on its axis,

But the equator
rotates faster than the poles.

The sun twists itself up,

And the magnetic field
twists with it.

It rotates faster at
the equator than at the poles,

Twisting and tangling
its magnetic field

With each rotation.

The result -- Magnetic mayhem.

So, when these fields emerge
from the surface of the sun,

They have all this stored energy
in them.

They're, like,
all twisted and knotted,

Like rubber bands
you just twist and knot

With all this energy in it.

If you ever twist and twist
and twist a rubber band

And pull it straight,

You can tell,
you can feel that tension in it.

Where the magnetic lines twist,

Flows of plasma
containing our photon

Can't reach the surface.

So, what happens is you have
these packets of gas

Which reach the surface,
cool off,

But are trapped right there
by the magnetism.

A patch of the sun goes dark

Where light can't escape.

A sun spot is born.

But in that tangle
of magnetic lines,

Something
eventually has to snap.

The magnetic fields
are very unhappy.

They don't like
the state that they're in,

And all they want to do
is unravel.

Huge loops of magnetic energy

Arch out over the sun spots.

Twisted and unstable,
desperate to spew their energy,

They create a magnetic bomb
primed to explode.

And so, if one magnetic
field with stored energy

Sees another magnetic field,
those two look at each other

And say, "hey, if we connect, we
can get rid of a lot of energy."

They do so, they reconnect.

Baddow!

It's a huge explosion,
and we call it a solar flare.

And this can be equivalent
to millions of nuclear weapons

Exploding simultaneously.

Solar flares
erupt outwards into space

At up to 4 1/2 million miles
an hour...

...releasing massive amounts
of energy.

Magnetic fields
are throwing plasma

From the surface of the sun.

Suddenly, there's a large
outpouring of light.

After nearly a million years,

Our packet of light
finally makes its escape.

It's free,

Catapulting out along
with trillions of other photons,

But their journey
is far from over.

Most hurdle onwards to
the far reaches of the cosmos,

To strange, new worlds.

After a nearly
million-Year journey

Through the most hostile
environment in the solar system,

Tiny parcels of light --

Photons -- Finally burst
from the sun's surface.

They're free.

They basically are free
to leave this arduous journey

That they've been on in the sun.

And then they fly out
at the speed of light.

So, it's kind of a "breaking
out of prison" type of feeling

For those poor photons.

They speed out into empty space

At 186,000 miles per second.

And just 8.3 minutes
after it leaves the sun,

Our photon reaches earth.

The next time
you look at a star in the sky,

You might consider
the amazing journey

The photons have taken on
their way to reaching your eye.

They were created
by nuclear reactions

Deep in the core of the stars,
and then they bounced around

And got degraded
into lower energy photons.

And then in the convective zone,

They were carried
by mass motions of gas.

And finally, at the edge,
they were set free.

And they traveled unimpeded
and finally reached your eyes.

Our photon finally arrives,

Smashes into a leaf,
and passes on its energy.

This is photosynthesis,

The fundamental link
in our food chain.

Finally, carrying energy
born inside the sun's core,

Our photon and billions like it

Ignite the primal fires
of life on our planet.

The sun's light creates
our fuel, drives our weather,

Churns our seas.

Every single day,
enough photons hit the earth

To power our civilization
for 27 years.

The sun's light is more
than just warmth and heat.

It provides everything
we need to survive.

Without light, we are nothing.

All of the energy
that powers our biology,

The thing that makes our planet
warm, that makes life possible,

That all comes from the sun.

Trillions of photons
hit the earth every second,

Each delivering
life-Giving energy.

But for the unimaginable number
who pass us by,

The journey is far from over.

Around 80 minutes
after leaving the sun,

They reach saturn.

After four hours, neptune.

Once a photon
leaves the surface of the sun,

It's free to travel
as far as it can,

And as far as it can can be
literally across the universe,

Billions of light years away.

They shoot
past the outer reaches

Of our solar system
in just 18 hours.

Here, the sun is a dim speck
in the distance.

But the photons keep on going,
out into deep space.

In 1,200 years,
some of the photons

Reach the red dwarf star system
kepler-62,

A solar system with potentially
habitable earth-Like planets.

In our galaxy,

There are billions
of earth-Like planets.

If there is life out there, can
it see the light from our sun?

If aliens exist out there,

They could easily
see the light from our sun.

If they're sufficiently nearby,

The sun might be
a naked-Eye star in their sky

Or with telescopes,

They would be able
to detect the sun

Even from
vastly greater distances.

So,
there's a distinct possibility

That aliens are studying our sun
right now without realizing

That we're here trying
to study the universe, as well.

Hurdling on,

The photons pass the horsehead
nebula in 1,500 years

And the pillars of creation
in 7,000.

At these distances,
the light from our star

Is too small to be seen
with the naked eye,

But it would be visible
with a powerful telescope.

And with the biggest telescopes

That we can create here on earth
or in space,

We can actually see
the light from stars

At the other end
of the universe,

Over 10 billion light years
away.

And so the light from our sun is
traveling across the universe.

So, the light from our sun,

The light from the earth,
travels essentially forever.

The next time you're out
under a clear sky

And you look up,

You might want to wave
because somebody out there

Might be able to see you
and wave back.

Our tiny star
is visible across the universe

If someone is looking.

There isn't a single
place in our visible universe

That you wouldn't be able
to see the sun from,

And maybe that's heartening.

Maybe there's some evidence
of our existence

At the other end
of the universe.

Won't get there
for billions of years,

But at least
maybe we won't be forgotten.

A journey that started
deep inside the core of the sun

With a photon,
a million-Year struggle

To finally escape
the sun's grip.

Once free, our photon

Brought energy, heat,
and life to our world.

Light from our sun joins light
from trillions of other stars

Journeying through the universe,

Spreading energy
throughout the cosmos.