Remember when you were a kid and everything was simple and you were told there were just
three states of matter: solid, liquid, and gas?
And then you got older and learned that plasma existed and you thought, “Ok, now I know
everything, it can’t possibly get more complicated”?
Well, it just got more complicated.
Scientists have found a new state of matter that is a solid and a liquid at the same time,
and they used artificial intelligence that could lead to future discoveries about what’s
happening inside planets and stars.
Scientists at the University of Edinburgh discovered that under extreme pressure, the
metal potassium starts behaving very strangely.
In normal conditions, a bar of pure potassium is pretty unremarkable.
I mean, aside from its tendency to explode if you get it wet.
But dry potassium atoms link up and form orderly rows that conduct heat and electricity well.
For a long time, scientists thought that was all there was to potassium’s structure,
until over a decade ago when scientists put sodium under extreme pressure.
At 20,000 times earth’s atmospheric pressure, sodium transforms from shiny to transparent,
and from a conductor to an insulator.
X-ray images showed the crystal structure had gone from simple to complex.
Sodium is an alkali metal just above potassium on the periodic table, so scientists reasoned
if it behaves oddly under pressure, maybe potassium does too.
And indeed, at extreme pressures, potassium atoms rearrange themselves from orderly rows
into a much more complicated structure.
They form five tubes, arranged in an X shape.
Edge on it would look like a five on a playing die.
In between the outer tubes are chains of potassium atoms.
Researchers describe it as two loosely linked sublattices, with the tubes acting as “host”
atoms while the chains were “guest” atoms.
When researchers turned up the heat on their high-pressure potassium, that’s when things
got weird.
X-ray images showed the chains disappeared.
To figure out where they went, they turned to computer simulation.
They trained a neural network using small groups of potassium atoms until the artificial
intelligence understood quantum mechanics well enough to simulate it on a larger scale,
up to 20,000 atoms.
Can we just take a moment to appreciate that computer science is at the point that software
can teach itself quantum mechanics?
When the computer model simulated potassium atoms at 20,000 to 40,000 times atmospheric
pressure, and between 400 and 800 Kelvin, it showed that the chains between the tubes
melted into liquid, while the tubes remained solid.
The potassium was in both states at once.
The researchers described it as though you had a sponge that leaked water… except the
sponge is also made of water.
They dubbed this new phase of matter the “chain-melted state.”
While that is objectively fascinating, you may be wondering, “So what?
When is potassium going to be under those conditions?”
Potassium could exist in this state in the earth’s mantle, though it’s rarely in
its pure form, what with its preponderance to react violently and explode.
The machine learning technique that developed the computer model, however, can be used for
other elements in extreme situations beyond potassium.
Conditions are pretty tame on Earth’s surface, but in the universe, extreme temperatures
and pressures are the norm.
Inside planets and stars matter could be doing all sorts of odd things.
Thanks to artificial intelligence we might be able to peel back the skin of alien worlds
to take a peek at what’s going on under the surface.
Fun Fact: This computer model worked really well, not only simulating the chain-melted
state, but all of potassium’s fourteen known phase transitions.
That’s more phases than I went through in high school.
If you love matter science check out this video here about scientists finding a new
state of water hidden in our earth’s mantle.
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