superfluidity

A property possessed by a fluid that has zero viscosity. The classic example of a fluid possessing this property is helium 4 cooled below 2.2 kelvin. In helium, the property is thought to appear when about 10% of the atoms become a liquid Bose-Einstein condensate, in which atoms lose their individual identities.

The behavior of superfluid helium is astonishing, defying commonsense notions of how matter is supposed to act. For example, it can spontaneously climb the walls of its container.

The property was discovered in 1938 by Pyotr Kapitsa and John F. Allen.

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