Hydrogen is the most abundant element in the
universe, thanks to it being simply one proton
paired with one electron.
Here on Earth we usually see it bound to oxygen
to form water, and very rarely hydrogen atoms
pair up and exist as a gas in our atmosphere.
But theoretically in the right conditions
hydrogen alone can act as a liquid metal,
and learning more about it could answer some
mysteries about planets in our solar system.
We know Jupiter and Saturn are mostly Hydrogen
based on their densities, which is why they’re
called the gas giants.
But they’re not puffy clouds all the way
down as the name might suggest.
Only the thin outermost layer is gaseous.
Under that, the pressure compresses the hydrogen
into a liquid state, and further down still
the hydrogen takes on metallic properties.
Most elements in the periodic table are metals.
Their defining characteristic is they pass
electrons freely amongst each other, like
a shared pool of electrons.
This makes them good conductors of heat and
electricity.
Normally the Hydrogen we see on Earth doesn’t
behave like a metal, but at about 13,000 km
below Jupiter’s gaseous surface, things
are different.
Like a substitute teacher, with enough pressure
those hydrogen molecules snap.
In fact the hydrogen atoms dissociate entirely
into free electrons and protons.
The pressure inside Jupiter gives it the properties
of a metal: those electrons can flow freely
from proton to proton, making the hydrogen
conductive.
We think this metallic hydrogen could account
for the magnetic fields surrounding Jupiter
and Saturn, instead of a molten iron core
like inside Earth.
But to understand metallic hydrogen better
we have to make it, and that’s no easy task.
It’s not like we can scoop some up from
deep inside Jupiter, instead we have to recreate
those conditions somehow here on Earth.
I am very happy to report that one leading
method involves giant lasers.
The lasers, all 168 of them, are used to send
shock waves through a sample of ultracool
liquid deuterium, an isotope of hydrogen with
one neutron.
The waves compress the deuterium to six million
times earth’s atmospheric pressure while
keeping the sample below 1,700 degrees celsius,
or what physicists call “cool.”
At least they think it’s that cool, because
measuring the temperature inside the shock
wave isn’t possible and instead is inferred
through computer simulations.
Still, the scientists concluded liquid deuterium
becomes metallic at 2 million times the pressure
of Earth’s atmosphere.
That contradicts another lab’s findings
that the transition happens at around 3 million
atmospheres of pressure.
Each lab politely and professionally says
the other one must have incorrect temperature
estimates, and that their own results are
the true and correct ones.
That’s about the closest scientists get
to reality show drama and I for one am living
for it!
There’s been even more drama around a 2017
Harvard experiment’s attempt at making metallic
hydrogen.
Using the tips of two diamonds like a vise,
scientists claimed they crushed a hydrogen
sample to nearly 4.9 million atmospheres until
it wasn’t just metallic, but solid as well,
a world first.
They were going to send it to another lab
for study, but wouldn’t you know it, just
before shipping it they decided to check the
pressure with a laser one more time for good
measure, and the diamonds shattered to dust.
The sample was lost.
This has lead other scientists to speculate
that it didn’t actually… happen.
Still, the Harvard scientists think the lost
hydrogen could still be in a solid state,
even with the pressure lifted.
It might even be a room temperature superconductor,
which would revolutionize materials science.
But finding the 10 micrometer wide sample
in a pile of diamond dust is next to impossible.
Darn.
Funny, we go through all this trouble to create
a speck of metallic hydrogen, but thanks to
Jupiter and Saturn’s vast sizes it’s the
most common form of hydrogen among all of
our planets.
Sometimes there are drawbacks to living on
Earth.
While you’re here subscribe for more videos,
like this one about how Jupiter could be the
reason for life on Earth.
Some scientists don’t believe the Harvard
experiment made solid metallic hydrogen because
at a high enough pressure the hydrogen can
diffuse right through the diamond!
Thanks for watching, I’ll see you next time
on Seeker!
