At supercold temperatures, hydrogen molecules first condense into a liquid, then a solid with the molecules intact. More than 80 years ago, the physicists Eugene Wigner and Hillard Bell Huntington predicted that hydrogen, under high enough pressures, would turn metallic, with the hydrogen molecules broken apart and the electrons squeezed loose. Scientists have momentarily transformed hydrogen into a liquid metallic state with violent shock wave experiments. But so far, no one has convincingly demonstrated the solid metallic hydrogen state predicted by Wigner and Huntington. If the sample survives without breaking, Dr. Silvera said he wanted to then open it up, relieving it of pressure, and see if there is a speck of solid metallic hydrogen still inside.

Source: New York Times January 26, 2017 20:02 UTC