A supersolid is a special quantum state of matter where particles form a rigid, spatially ordered structure, but also flow with zero viscosity. A supersolid combines the properties of solids with those of superfluids.
At very low temperatures, close to absolute zero, matter behaves strangely: fluids flow without friction (superfluidity), metals float (superconductivity). A supersolid is, in fact, a material with some “superfluid” characteristics: it can penetrate itself and other porous materials. Like a ghost.
Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport.