Abstract
At very low temperatures, the motion of atoms can no longer be described by the classical laws of Newtonian mechanics, but instead follows those of quantum mechanics. Atoms in some gases lose their identity. Thus, in Bose-Einstein condensation (theoretically predicted as early as 1925, but experimentally realized only in 1995), the waves of the atoms merge into a single giant wave of matter, and the system behaves like light in a laser beam. Superfluidity manifests itself in the disappearance of viscosity.
