Momentum Operator

Momentum Operator

In quantum mechanics, momentum (like all other physical variables) is defined as an operator, which "acts on" or pre-multiplies the wave function ψ(r, t ) to extract the momentum eigenvalue from the wavefunction: the momentum vector a particle would have when measured in an experiment. The momentum operator is an example of a differential operator.

At the time quantum mechanics was developed in the 1920s, the momentum operator was found by many theoretical physicists, including Niels Bohr, Arnold Sommerfeld, Erwin Schrödinger, and Eugene Wigner.