CLASSICAL UNDERPINNINGS OF GRAVITATIONALLY INDUCED QUANTUM INTERFERENCE

We show that the gravitational modification of the phase of a neutron beam [the Colella-Overhauser-Werner (COW) experiment] has a classical origin, being due to the time delay that classical particles experienc e in traversing a background gravitational field. Similarly, we show t hat classical light waves also undergo a phase shift in traversing a g ravitational held. We show that the COW experiment respects the equiva lence principle even in the presence of quantum mechanics. [S1050-2947 (98)03802-5].