“Quantum mechanics has done it again. In an experiment with supercooled helium, researchers at Penn State say they have found that as a solid ring spins around, part of it can remain perfectly still.
At ultracold temperatures, matter often behaves far differently than it does in everyday experience. For instance, many materials turn into superconductors, able to conduct electricity with no resistance, because electrons coalesce and move in synchrony without hitting the surrounding lattice of atoms.
In a similar way, other materials at low temperatures become superfluids, which flow without viscosity to slow them down.
The new experiment suggests a new state of matter: a supersolid.”
More here from the New York Times.