Superfluidity

Superfluidity is a state of matter in which the matter behaves like a fluid with zero viscosity. While originally this phenomenon was discovered in liquid helium, it has found applications not only in the theory of liquid helium but also in astrophysics, high-energy physics and theories of quantum gravity. The phenomenon is related to the Bose–Einstein condensation but not identical: not all Bose-Einstein condensates can be regarded as superfluids and not all superfluids are Bose–Einstein condensates.