Forget a doomsday
asteroid or melting permafrost.
It's the freezing of the Earth's core
that will end the world in today's episode.
Or would it?
Because maybe, just maybe,
we could save the world
by heating Earth from the inside.
You've probably never noticed
that the Earth's core is freezing.
But it is.
It's just happening very slowly.
About 4.5 billion years ago,
the entire core was molten.
But over billions of years,
the Earth has slowly cooled
from the inside out,
causing parts of its molten
iron outer core to freeze.
And if this process significantly
sped up in a flash freeze event,
we'd need to do something about it.
The Earth's core does more for our planet
than you might imagine.
Without it,
what would happen to you?
Earth has a magnetic field that surrounds it
and protects you from radiation.
This field is created by,
you guessed it,
our planet's core.
Heat transfers from the super hot
inner core, through the outer core,
and into the mantle.
This heat exchanging process,
called convection,
creates a current of liquid metal
in the outer core.
And the flow of liquid metal generates
electrical currents, which extend into space
to form that essential magnetic field.
But if Earth's core were frozen solid,
there would be no current in the outer core.
And there would be no magnetic field.
All of a sudden,
we would have no protection
from the ultraviolet
radiation bombarding Earth.
You'd have no more fun in the Sun,
because now the Sun would be deadly.
Even plants wouldn't be able
to survive the intense UV rays.
You'd have to grow all your food inside,
as if you lived on an alien planet.
And you basically would be.
Because the Earth's magnetic field
also keeps our atmosphere in place.
Without it, solar winds would strip Earth
of its breathable and safe atmosphere.
Our planet would start looking
more like Mars than the Earth
we know and love.
You could jump on a spaceship,
assuming those still exist,
and leave Earth.
But where would you go?
Any other planet would be just as hostile
as the dying Earth,
if not more.
Your best bet would be to dedicate
every brain cell you have to help the world
reheat the Earth's core.
But could we do it before it's too late?
Well, we just might be able to.
But we'd need to know what
made the core so hot before it froze.
Well, there are three reasons.
The first is left over heat
from the process of accretion,
which is how Earth formed.
Basically, Earth was once
just a tiny core seed.
But it was able to gather more
and more material into itself,
growing larger and larger.
Every time a new material crashed
into the growing Earth,
it generated incredible amounts of heat,
which got trapped inside the core.
The second reason
Earth keeps its toasty inner temperature
is called frictional heat.
When Earth was young,
it underwent gravitational sorting.
The denser and heavier parts,
including iron and nickel,
sank into the center.
The less dense substances, like oxygen and water,
floated outward.
This created friction and generated heat.
The main reason our planet is so hot
is because of radioactive decay.
As radioactive isotopes
decay in Earth's mantle,
they produce heat.
But could we successfully
reproduce any of these phenomena?
Well, we can't go back
in time to when Earth formed.
And we can't create more friction in the core.
So we'd only have one method left to try.
And that would be
adding more radiation to it.
Which means we'd need to drill a giant hole.
But not just any hole.
We'd have to drill
all the way down to the mantle,
where radioactive decay happens.
So we'd drill through the ocean floor,
where the crust is usually thinner.
No one has ever drilled
into the mantle before.
The closest anyone got was back in 2005,
when the Integrated Ocean Drilling Program
bored a hole 1,416 m (4,644 ft) deep
in the North Atlantic Ocean.
But let's say that the world would come together
under the threat of impending doom
and create the most sophisticated drill ever.
Once we drilled beneath the seafloor,
all we'd have to do
is pump the mantle full of potassium,
uranium and thorium.
These elements would decay
and generate heat.
It could, eventually.
But there would be a drawback.
All the heat from radioactive decay
would be in the mantle,
not the inner or outer core.
It wouldn't recreate
the life-saving magnetic field.
For that,
we'd need the outer core to melt.
So back to the drawing board.
It looks like we'd need to do
something we've never done before
if we want to save humanity.
And this time we'd have to drill all the way
to the outer core,
20,900 km (1,802 mi) deep.
Because we'd be building
an Ultra High Energy Particle Accelerator
thousands of miles long,
deep into the Earth.
This particle accelerator
would harness the Sun's power
and pump energy into the Earth's outer core.
Once the outer core reheats,
it would generate the electrical current
and create the magnetic field.
But here's the thing.
The pressure inside the inner core
is so extreme that iron atoms
are not able to become liquid.
This is why the inner core
is so incredibly hot and solid.
The intense pressure
would make any tunnel we tried to drill
immediately collapse.
So even if we could
build that advanced particle accelerator,
we wouldn't be able to use it.
But at least we would
give it our best shot.
Maybe you should've
hopped on that spaceship.
There we are yet again,
the freezing of the Earth's core
would be death to us all.
Luckily, scientists estimate that it would take
91 billion years for the core to solidify completely.
And seeing how the Sun will become
a red giant star in about 5 billion years,
the Earth cooling is the last thing
you'd need to worry about.
Now, an exploding Sun
wouldn't be all that fun to see.
But that's a story for another WHAT IF.