Position and Spin Operators, Wigner Rotation and the Origin of Hidden Momentum Forces

Abstract

Using a position operator obtained for spin ½ particles by the present author and Wigner, we obtain a quantum relativistic result for the hidden momentum force experienced by particles with structure. In particular, our result applies to the hidden magnetic forces manifest in some problems of electromagnetism. We also discuss spin and orbital angular momentum operators, as well as Wigner rotation.