How Fundamental is the Curvature of Spacetime? A Solar System Test

Are some paths and interactions immune to the gravitational curvature of spacetime? The paths of virtual particles might be – the effect is unexplored experimentally. Were a quantum theory of gravity moderated by virtual gravitons that are themselves susceptible to gravitational curvature, to obey the weak equivalence principle, and to follow null geodesics, then gravitational acceleration might be slightly but detectably enhanced by the gravitational lens effect of our Sun at outer solar system locations opposite nearby stars. It is shown that this “virtual equivalence principle” is testable by precisely placing accurate clocks out near the orbit of Neptune. ∗Department of Physics, Michigan Technological University, Houghton, MI 49931, USA