PATH-DEPENDENT PHASE-SHIFTS IN ISOLATED SYSTEMS

The Aharonov-Casher effect in a closed system is discussed. In this mo del, the charge on the wire is produced by a conducting bar moving in a magnetic field If one considers the neutron to be a classical partic le and the moving bar to be a quantum object, then the wave function o f the bar acquires a phase shift equal in magnitude but opposite in si gn to the usual phase shift of the neutron wave function. It is also s hown that in any closed system, a path-dependent phase shift of one pa rt of the system is always accompanied by an opposite phase shift of t he remainder of the system. This result follows directly from the prin ciple of least action.