Why Metallic Hydrogen Is the Holy Grail of High Pressure Physics

Making hydrogen a metal takes a lot of pressure. But after a group of scientist’s lost the world’s first sample, the pressure is really on.

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, 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.