Original subtitles

*

The blueprint of the universe is drawn with magnetic lines.

Magnetic fields help stars ignite.

They shape entire galaxies.

And the same force that creates magnetism

is the cement that holds all matter together.

Without this universal glue, there would be no stars, no planets,

no people and no light.

December 27th, 2004.

While America slept,

an immense shock wave rippled through space.

The invisible wave had been travelling at the speed of light

for 50,000 years.

It shook the Earth's protective magnetic field...

..ripped out a chunk of our upper atmosphere

and blinded several satellites.

It was one of the most tremendous events

ever seen in modern astrophysics.

The blast of energy was huge,

but the Earth's protective magnetic field

did just enough to prevent serious damage.

Even so, scientists were rattled.

They searched for the culprit.

Was it a giant supernova?

The jet from a massive black hole?

But the usual suspects weren't to blame.

This was something new.

The source was found on the other side of the galaxy -

a tiny star with a magnetic field stronger than anything

scientists had ever seen before.

From 50,000 light years away,

this little object, just a few miles across,

has such a hissy-fit that it physically affected the Earth.

Fortunately, this magnetic death-star was far away.

Even so, science had woken up to the terrifying power of magnetism.

Magnets appear to be simple -

they either stick together or push apart.

You're probably familiar with playing around with magnets.

You get 'em close together and it's almost like they reach out

and grab each other, pull each other together.

But if you flip them around, they repel.

A magnet can attract and repel.

This remarkable feat relies on the two magnets

swapping packets of energy that physicists refer to as particles.

It turns out that what's going on is that there are particles

that are being exchanged between this magnet and this magnet,

and those particles are called photons.

These are the same photons that create light.

Photons are the packets of energy that our eyes detect

to see the world around us.

Plunging down to the subatomic level

reveals how photons are at the very heart of magnetism.

This bizarre world is ruled by the laws of quantum mechanics

and inhabited by tiny objects such as atoms,

each a nucleus surrounded by a cloud of electrons.

Think about the structure of an atom.

There's a positive charge to the nucleus

and then the electrons have a negative charge.

These two attract each other.

To explain this force,

quantum physicists think that both the nucleus and electrons

spit out short-lived bursts of photons.

The oppositely-charged particles absorb each other's light

and this draws them together.

The force is known as electromagnetism.

Atoms themselves would not hold together

if it weren't for electromagnetic forces.

Electromagnetism also sticks atoms together

to form molecules.

And it sticks the molecules together to make us and everything around us.

Electromagnetism is responsible for the very structure of our matter -

atoms holding together.

Molecular bonds in our bodies, those are bound together

by electromagnetic interactions

and therefore they're bound together by light.

A universe without electromagnetism would come apart at the seams.

If electromagnetism was turned off, matter would dissolve.

Everything would just... bleurgh...fall apart.

I could probably, with my superhuman strength, hold myself together,

but the rest of you are doomed.

Without electromagnetism, nothing would be solid.

When you touch something,

that's the electromagnetic force as well.

We have electrons in our atoms and they repel each other,

and when you try to touch something,

those forces keep you from actually physically touching it.

(BEEPING)

The reason I don't fall through the floor

is not that the floor is particularly solid,

most of the floor is empty space.

It's the electric forces of the atoms in the floor

against the electric forces of the atoms in my body

that hold me up.

Just those little forces of those few atoms

are enough to hold me up

against the entire gravitational force of the Earth.

Electromagnetism rules.

The electromagnetic force is far stronger than gravity.

And now scientists are now beginning to understand its power

on a cosmic scale.

Turn back the clock

to when the universe was just 380,000 years old.

There were no stars or planets,

just a broiling dense soup of excited protons and electrons,

hurtling through a sea of high-energy photons.

In the early universe, there were no atoms,

because the energy was so intense

that separate charged particles existed in a very hot, dense primordial soup.

Then, as the universe cooled, everything changed.

Between the time the universe was about a minute old

and the time when the universe was 300,000 years old,

electromagnetism slowly came to the fore.

And protons and electrons began to feel electric forces

and combine as atoms.

Electromagnetism essentially began to determine the dynamics of matter

and the ultimate formation of everything we see.

Now electromagnetism could flex its muscles.

It pulled electrons and protons together to form hydrogen,

the first atom.

The hydrogen atoms bunched together to form clouds of hot gas.

These newly formed clouds glowed...

..and the lights of the universe were turned on.

As the newly formed atoms swirled around each other,

their combined magnetic effect grew stronger.

The smallest magnets in the universe are atoms themselves

that create, basically, mini bar magnets

that are on the scale of the subatomic world.

The hydrogen micro-magnets began to align,

generating vast highways of strong magnetic fields.

And then over time what happens is

that these magnetic fields begin to grow.

And so all the magnetic fields we see today in our universe

can really be attributed to these primordial magnetic fields.

Electromagnetism shaped the early universe,

but it didn't stop there.

It went on to help with the next milestone

in the universe's evolution - the stars.

The old picture of how stars are formed

is all you need is gravity and time.

But we've come to understand

that the problem's a little trickier than that.

That, actually, magnetic fields play a fundamental role.

So it's possible that without these magnetic fields,

stars themselves would not exist.

A billion years after the Big Bang,

magnetism injects life into the universe's first ever stars.

*

*

Astronomers once believed that star formation was simple...

..a vast cloud of interstellar gas drawn together by its own gravity.

Temperatures and pressures rise as the gas compresses...

..until it's hot enough and dense enough

for nuclear fusion to ignite the core.

And a star is born.

At least, that's what the scientists used to think,

but recently, they discovered a problem with this simple theory.

The primary mover when you're forming a star is gravity.

The material condenses in the centre to form a star.

And as that star forms, there's material swirling around it,

attracted to that central mass by its gravity.

But there's a problem -

this stuff has what's called angular momentum.

Angular momentum stops the Moon from falling into the Earth.

Scientists realised that this same force

would stop the gas from falling into the forming star.

So the star would never reach critical mass and never ignite.

Angular momentum and gravity are basically in a fight.

The angular momentum is what keeps things spinning around out here,

whereas gravity wants to tug it in towards the middle.

If somehow we could lose that angular momentum,

then star formation would progress.

Before a star can be born, it needs to draw in enough gas

to boost the temperature in its core to 15 million degrees Celsius.

Scientists realise that for that to happen,

something would have to break the deadlock

between gravity and angular momentum.

That's where magnetism can play a role.

The magnetism of the protostar, the forming star,

can actually affect the disc and slow it down

and actually let it drop in and help the star itself form.

When charged particles move, they produce magnetic fields.

In this case, the swirling gas and the spinning star

generate magnetic fields that are powerful enough

to slow the gas cloud down.

Magnetism works like a cosmic brake.

It slows down a little bit and eventually spirals into the centre,

gravity starts to win.

Gravity beats out that angular momentum

and star formation happens.

Finally slowed by the magnetic field, gravity drags the gas ever closer,

crushing it and heating it until...

..ignition.

A star is born.

12 billion years ago, the first stars burst into life.

Without magnetism, we'd still be in the dark.

But magnetism can also bring terrible destruction...

..and some of these early stars

are destined to transform into magnetic monsters.

The transformation begins when the star runs out of fuel.

A sudden and violent reaction takes place.

It implodes.

This is known as a supernova.

The star's outer layers are blown out into space.

What's left behind, including the magnetic field,

is crushed by gravity.

If you look at stars,

just about all stars have strong magnetic fields at their surface.

What happens is that if a star dies and it collapses,

the same amount of magnetic field must still be present.

So if the surface area of the star

is decreased by a factor of 1,000 or 10,000,

then that means that the magnetic field intensity must increase by that same amount.

What's left is an ultra-dense, ultra-magnetic ball,

roughly the size of a city.

These objects are more than a trillion times denser than lead

and they have the potential to harbour

the most extreme magnetic fields ever seen.

They are called magnetars.

These dense balls have very, very strong magnetic fields.

In fact, the strongest magnetic fields in the universe.

The magnetic field can be more than a trillion times stronger

than the Earth's field.

If you got very, very close to a magnetar,

that strong magnetic field might possibly rip you apart.

Because your atoms just can't stay together

in the vicinity of such a strong magnetic field.

Scientists know of 23 magnetars in the Milky Way,

but they think there could be many more.

One, SGR-1806-20,

located 50,000 light years away, on the other side of the galaxy,

was the same magnetic monster that unleashed an assault on the Earth in 2004.

The electromagnetic shock wave was triggered by a starquake.

That's like an earthquake, but it's on star.

And the crust of the star slipped about this much,

literally about a centimetre, the width of your finger.

But this was far larger than any earthquake

this planet has ever seen, millions of times stronger.

And the magnetic field is coupled with the matter in it.

So when the crust slipped, so did the magnetic field.

And it launched a blast of energy so powerful

that 50,000 light years away, it physically affected our planet.

This tiny slip had a colossal effect.

If this thing had been a lot closer,

the effect on us would have been huge.

If a magnetar erupted a couple of light years from Earth,

it could devastate our planet.

There could be a burst of radiation

that could literally strip away our atmosphere.

A blast from a magnetar could blow our atmosphere into space,

leaving the planet's animals gasping for air.

In this near-vacuum, our oceans would quickly boil away

and Earth would become a lifeless ball of rock spinning through space.

In the cosmic menagerie of beasts and ghouls

and things that go bump in the night,

I think magnetars are at the very top of the list of things that really are pretty scary.

Magnetars have alerted scientists

to the incredible power of electromagnetism.

And yet, for many years,

scientists believed it was a minor player

in the evolution of our galaxy.

But new data has revealed a magnetic field on a cosmic scale.

For centuries, mankind has been studying the night sky...

..mapping out the gas, dust and stars.

But we've missed a structure as big as the galaxy itself...

..a vast magnetic field

that measures more than a quintillion kilometres across.

A single atom can have a magnetic field.

A bar magnet can have a magnetic field.

Our planet does, the sun does.

And, in fact, structures even as large as galaxies can.

A galactic magnetic field is huge.

It's basically the size of the entire Milky Way.

The field is far stronger than anyone had realised.

If you add up the magnetic fields from the stars

and the gas that fill our galaxy...

..it still can't account for all the magnetism we see.

Something else is powering it...

..but what?

Where do all of these big magnetic fields come from?

Where are the magnetic fields coming from

that are pervading the galaxy?

Scientists got the first clue to the origin

of these mysterious magnetic fields

by looking at the remains of dead stars.

Records suggest that Cassiopeia A suffered a cataclysmic

supernova explosion around 300 years ago.

What remains is a vast ball of gas and dust,

hurled out into space by the exploding star.

As the gas expands outwards in the shape of a giant bubble,

it crashes into neighbouring clouds of interstellar gas.

Astronomers have discovered

that these collisions generate strong magnetic fields.

And the extra magnetism contributes

to the larger galactic magnetic field.

The question is - by how much?

A new breed of experimental cosmologists

are determined to find out.

Jena Meinecke is using one of the world's most powerful lasers

to simulate supernova shock waves in the lab.

What I can do is use large lasers,

in fact, the largest lasers on Earth,

to create supernovas which can fit in the palm of your hands.

Jena starts the experiment

by placing a small piece of carbon rod into the laser target area.

We put all six laser beams onto this carbon-rod target

in a gas-filled chamber.

And so what happens is is that this material

will expand out ballistically, creating a shock wave.

And what we hope is that this shock wave

will generate magnetic fields.

All right, locking down for a shot.

(ALARM WAILING)

Everyone evacuate.

(BEEPS)

Hi, Laser Bay, this is Target Area West,

we're locked down and ready for a shot.

Full energy on all six beams.

The laser operations team focusses on the tiny carbon target.

The laser heats the target to over a million degrees.

The carbon explodes,

creating a shock wave that slams into the surrounding gas.

Success. We've got our shot.

So it looks like our laser hit the target quite well.

We have this beautiful shock wave here that's been emitted.

So the laser came in this way, hit our carbon rod.

This is all the sort of debris that was moving out quite fast,

and then this is the shock wave which generated as a result.

Instruments detected strong magnetic fields

along the line of the shock wave as it struck the gas around it.

So this shock wave is moving out into space

and this is what's creating all of these magnetic fields

along this front.

Jena thinks a similar process

creates vast magnetic fields in space.

Supernova shock waves slam into gigantic interstellar gas clouds

like a tsunami,

raising a fast-moving front of turbulent gas.

Charged particles inside the gas cloud

tumble over and over each other...

..generating powerful magnetic fields that extend far out into space.

So what you have is a mixing of charged particles

that are now spinning around and moving fast in chaotic ways.

Whenever you have that kind of activity,

you have magnetic fields.

It seems that powerful magnetic fields break out

whenever clouds of interstellar gas collide.

This phenomenon is not just limited to supernova explosions,

because they aren't the only cosmic phenomena

with the power to shock.

Overfed black holes blast jets of super-heated matter into space.

These jets pierce through gas clouds,

producing turbulence and powerful magnetic fields.

And sometimes, drifting clouds of interstellar gas

smash into each other,

creating huge magnetic storms.

Collisions like these are the steroids

that boost the Milky Way's magnetic muscle.

And the distribution of this magnetic bulk may be the key to unlocking

one of the greatest mysteries in cosmology...

..why our galaxy is missing over a trillion stars.

*

*

The Milky Way is made up of more than 200 billion stars.

And yet, for astronomers, even this astronomical figure isn't enough.

That's because surrounding our galaxy is a vast halo of gas,

the perfect star fuel.

According to calculations,

it should have turned into thousands of billions of new stars,

but it hasn't.

One of things that's hard to understand

about the Milky Way is why there are actually so few stars.

Our Milky Way should have ten times as many stars as it does,

but it doesn't.

One of the big questions is why?

According to the rules of old-fashioned physics,

the colossal clouds surrounding the Milky Way

should have been sucked inside the galaxy's boundaries.

Here, the gas would have condensed under its own gravity

and formed into new stars.

But cosmologists now think that magnetic fields

are holding the gas back.

There's a huge amount of gas that comes way from outside

the galaxy that wants to fall in and then be available

for star formation.

What prevents all of that gas and dust that we know is out there

from turning into stars?

It might just be magnetic fields.

Magnetism now plays a key role in our understanding

of how galaxies form.

Ten billion years ago, the fledgling Milky Way

was nothing more than a vast ball of stars.

But over time, spin flattened the ball into a disc.

The disc grew as gravity sucked in more and more stars.

Gravity is ultimately first responsible

for the collapse of matter which form galaxies.

Once matter begins to move and interact...

..magnetic fields become important.

Early supernova shock waves created turbulence,

spreading magnetic fields through the infant Milky Way disc.

As the disc spun, these magnetic lines

wove a protective cloak around the young galaxy.

Here's the problem - in our galaxy, it's such a tangled web

of magnetic field lines.

And this magnetism can prevent stuff from falling in

on the centre of the galaxy.

This powerful magnetic web stopped the vast reserves of gas

from falling into the Milky Way.

Magnetic fields played a fundamental role

in keeping that gas out.

This puts the brakes on star formation

and keeps new stars from forming

as fast as we think they would in the Milky Way.

The galactic magnetic fields not only reduce the rate of star formation,

new evidence suggests they also determine the regions

where the stars that do form are born.

Making it more likely for stars to form along the web

of magnetic field lines that weave through the galaxy.

Thus shaping the distribution of stars,

including our own star - the sun.

Clues for this magnetic blueprint came from a galaxy

2.7 million light years away.

The Triangulum Galaxy boasts spectacular spiral arms.

Stars are bursting into life, all neatly lined up along them.

Astronomers realised that the spiral arms

traced out the galaxy's magnetic fields.

What we're beginning to see right now is that it looks like

we're discovering these gas clouds where stars are forming,

that are aligned.

And one way that this alignment could occur

is via the act of magnetic fields.

Magnetic fields lines act sort of like super-highways for charged particles.

Charged particles wanna track along them.

Charged particles in gas clouds within the galaxy

are directed along the spiral arms by magnetic fields.

Here, the gas clouds are denser,

allowing star formation to take place.

Gravity is responsible for the formation of galaxies,

but magnetism may make galaxies what they are.

Magnetism has shaped the galaxy.

But it's also responsible for protecting us

from our nearest and most dangerous threat...

..the sun.

The sun's scale and power is almost unimaginable.

It burns a staggering

five million tonnes of nuclear fuel every second.

The energy it releases powers most life on Earth.

But without magnetism to tame it, our star would destroy us.

The spinning molten core of Earth generates a magnetic field

that bursts from the poles,

cocooning our entire planet in a blanket of magnetism.

This invisible force-field deflects deadly charged particles

streaming from the sun,

protecting us and our atmosphere from catastrophic damage.

But this vital shield might be losing its power.

In the last, about, 200 years, it's weakened by about 10%.

And if it continues at this rate, in a couple of thousand years,

it might go down to nothing.

If it were to disappear forever,

we would be in trouble in the long run.

Our planet without magnetic protection would be doomed.

We only have to look at our planetary neighbour to see what would happen.

Mars may have once been like Earth,

with a thick atmosphere and water on its surface.

That's gone. Why?

Well, we know Mars doesn't have a very strong magnetic field,

and that means it can't protect itself from the solar wind.

These particles come streaming out of the sun

and they hit Mars's atmosphere and blow it away.

Its atmosphere was actually stripped off by the solar wind,

because it didn't have a protective cocoon of a magnetic field.

Today, if you look at Mars, it's cold, it's barren,

it's lifeless, because it doesn't have an atmosphere.

Understanding the Earth's magnetic field

is key to understanding our future survival on this planet.

Geophysicist Dan Lathrop and his team

have built a replica of the Earth's core to play out the evolution

of magnetic fields in fast-forward.

Lathrop wants to know if the Earth's magnetic decline

is part of a normal cycle of peaks and troughs,

or if it signals the beginning of a terminal decline.

Having an experiment like this

allows you to get closer to something

like a planetary core than could ever be done by any other means.

Liquid iron is too hot to handle,

so Lathrop fills his ten-foot ball with the next best thing -

12-and-a-half tonnes of liquid sodium metal.

When we run the experiment, the main thing that we're trying to understand is

how this swirling mass of liquid sodium, this turbulent, roiling flow of liquid metal

generates electric currents and magnetic fields.

And try to use that then to understand how planets' interiors

do the same thing.

Lathrop starts the motor,

spinning the ball, replicating how our planet rotates.

Inside the spinning ball, the molten sodium starts to swirl.

Charged particles race around the core.

OK, yeah, that's good. It's coming into view.

A magnetic field emerges from the poles of the ball.

It looks just like the one that protects the Earth.

Spontaneously, the magnetic field starts to weaken,

but then recovers again.

Lathrop believes the Earth's magnetic field will also recover.

And his experiment shows something else -

the magnetic poles are moving.

Amazingly, scientists have found that the Earth's poles do the same.

As we look at the Earth's magnetic field,

we can see that the direction the compasses are pointing toward

is migrating to the north at a rate of several tens of miles per year.

It's migrated off of Canada, it's moving now towards Siberia.

Will it keep going to Siberia and beyond that?

Or will it come back again and reach toward Canada?

It's hard to predict what will happen.

To try and predict the future,

scientists search for clues in our planet's magnetic past.

Planetary scientist Jani Radebaugh is in Hawaii,

home to Kilauea, the world's most active volcano,

making it the perfect natural lab to study Earth's magnetic history.

The great thing about lava flows is that they trap

the Earth's magnetic field inside of them

and then freeze it in place.

So now if we go and pick up the rocks

from these lava flows, we can actually find out

the orientation of the magnetic field in the past.

Lava contains particles of iron.

When molten, these iron particles

line up with the Earth's magnetic field.

Then, as the lava cools, this orientation is locked in place.

By digging down through layers of historic lava flows,

scientists have discovered a magnetic record

that stretches back for millions of years.

It shows the Earth's field doesn't just weaken and move.

From time to time, the whole field flips.

The North and South Poles actually swap places.

The field was aligned in one direction for a while.

And if you come up a little ways higher in that column of lava rock,

we find it was actually oriented completely the opposite direction,

180 degrees from where it is today.

It does that a number of times, dozens of times.

So that tells us that the magnetic field of the Earth

changes direction, not on kind of a regular basis,

but once in a while, spaced by tens of thousands of years,

maybe up to a couple of million years apart.

And it flips from north to south,

changing directions over the course of Earth's history.

How will the next magnetic somersault affect life on Earth?

The surprising answer - very little.

Biologists have dug deep into the Earth's fossil record

and discovered that magnetic flips aren't cataclysmic.

What we do know is that it doesn't take so long

that we're left unprotected for a long enough time

that life is wiped out.

We don't see mass-extinction events

around every uh... magnetic-field-flipping event,

and therefore, we know it must be relatively fast.

The Earth's magnetic shield

has protected life from the sun's radiation for billions of years...

..and it will continue to do so.

But we are different from our ancient ancestors.

We harness the force of electromagnetism

in every device that powers our technology.

And this puts us at risk

from a threat that could bring the human race to its knees.

*

*

The human race could be heading towards a major catastrophe

of our own making.

We've built our entire civilisation on electromagnetic foundations,

and there's a threat in the sky

that could bring it all down at any moment.

We depend on the sun for our life and for our civilisation,

but it can just as easily take that away.

We have wires running everywhere

and they're used to carrying currents.

But this infrastructure is in some level vulnerable

to activity on the sun.

Day after day, we're protected from the sun's solar wind

by our planet's magnetic field.

But the sun has a magnetic field, too,

and sometimes its magnetic lines become weapons of mass destruction.

These magnetic weapons are generated deep inside the star.

The sun is hot on the inside and that hot material rises up

from the centre and goes out toward the surface and back down.

This process is called convection.

And so these charged particles are moving around

and generating a magnetic field.

Now, unlike the Earth, which has one big magnetic field like a bar magnet,

inside the sun there are zillions of little magnetic fields

all rolling around and doing their own thing.

A surprising feature of the sun's surface

further distorts this chaotic web of magnetic fields.

The whole sun spins but it's not a solid object.

The equator actually spins faster than the poles

and the sun twists itself up.

When you twist magnetic fields, they get more energised.

Magnetic fields can store a vast amount of energy

and the sun has that to spare.

Now, if that were it, it wouldn't be a problem.

But what happens is sometimes these magnetic lines can snap.

When a magnetic field snaps, the surface of the sun erupts,

blasting out a magnetically-charged cannonball of particles.

This is called a coronal mass ejection or a CME.

A coronal mass ejection blasts out this energy,

there's a huge amount of subatomic particles.

Something like a billion tonnes, which will erupt out from the sun

and head out into interplanetary space.

This cloud of particles has its own magnetic field that goes with it.

And if that hits the Earth,

it can interact with our magnetic field.

When a CME smashes into Earth's magnetic field,

the impact can induce a surge of current in the power lines

that deliver electricity to homes and businesses.

All of our electromagnetic infrastructure,

all the power lines, the transistors, everything,

all of that can absorb this current and it can overload the circuit.

Causing blackouts and a lot of annoyance to society.

Around 150 CMEs hit Earth each year.

Some cause blackouts but nothing worse.

However, the sun has the potential to fire a doomsday CME our way.

First, the huge ball of charged particles

would smash into satellites orbiting the Earth.

(SATELLITE MALFUNCTIONING)

A big solar storm could actually affect satellites,

shorting them out.

We could lose communication, we could lose GPS.

GPS is used by every stock market across the globe.

Without satellites, the world's financial infrastructure could crash.

Aeroplanes would be grounded.

Shipping lanes closed.

Mobile communications would go dead.

We depend on all of this

for our monetary system, financial system,

for our civilisation.

After destroying satellites,

the energy of the CME would reach the surface.

Immense electrical currents would surge through power lines,

overloading entire grids across the planet.

Substations explode in a shower of sparks.

You can imagine an extreme solar event,

an explosion like we've never seen before

causing tremendous power outages.

You could even imagine all of the United States

having a massive blackout.

It would take years and billions of dollars

to fix the electrical infrastructure

and build and launch new satellites.

A huge storm could actually bring our civilisation to its knees.

Magnetism threatens to destroy our society...

..but our electromagnetic habit is a hard one to give up.

This same force protects us,

allowing life to flourish on our planet.

It helped build our sun

and even the galaxy we sit in.

Without magnetism, there would be nothing.

Magnetism affects processes that range from the formation of galaxies

to the formation of stars,

to the processes that power our very being.

Magnetism is central to our existence in the universe.

subtitles by Deluxe

From the atom up,

magnetism shapes every object in the cosmos.

It really is the ultimate force of mass construction.

It's responsible for the very nature of matter itself.

It's responsible for the Earth holding onto its atmosphere and its water.

Every day of your life

you have to remember you're here because of magnetism.