ON AN INTERPRETATION OF NON-RIEMANNIAN GRAVITATION

Motivated by the invariance of actions under gauge symmetries the defi nitions of standard clocks in theories of gravitation are discussed. W e argue that standard Einsteinian clocks call be defined in non-Rieman nian theories of gravitation and that atomic clocks may be adopted to measure proper time in the presence of non-Riemmannian gravitational f ields. These ideas are illustrated in terms of a recently developed mo del of gravitation based on a non-Riemannian space-time geometry.