Uranus and Neptune provided the first clues about what is now called “superionic ice,” per Quanta Magazine. Launched in 1977, the Voyager 2 probe eventually discovered that the planets’ magnetic fields appeared “lumpier and more complex” than planets like Jupiter, which had clear north and south poles. Scientists attributable this clarity to “dynamos” of superconductive fluids in its center, which work together to act as a giant magnetic rod running along the planet’s axis. At the time, it was believed that Uranus and Neptune’s apparent multiple poles would only be possible if their outer layers transitioned to solid, icy cores. In short, it seemed impossible. 

The original 1988 simulation illustrated that water morphs under extreme pressure and heat in a very particular way. Its hydrogen atoms split from oxygen and start zinging around, effectively reduced to protons (positively charged particles) as oxygen lines up along a crystal-like lattice as hard as metal. The protons conduct electricity just like metal, too, while their disorder makes the melting point of the substance rise so high that it could be subjected to extreme heat before further changing state. In other words, it becomes black and hot ice, where “ice” is defined as the solid form of the water molecule — not necessarily the stuff that chills your drinks.

Further tests incorporated not just classical but also quantum physics. And lo and behold, Nature magazine brought us the 2019 paper, “Nanosecond X-ray diffraction of shock-compressed superionic water ice.”