An Etymological Dictionary of Astronomy and Astrophysics

In the → Copenhagen Interpretation of → quantum mechanics,
the change undergone by the → wave function of a particle when a measurement is performed on the particle. The wave function collapses to one that has a definite value for the quantity measured. If the → position of the matter wave is measured, it collapses to a localized → pulse. If → momentum is measured, it collapses to a wave with a definite momentum. Same as → collapse of the wave function.

See also: → wave; → collapse.