Brian J. Pitts
History and Philosophy of Science Program and Philosophy Department, University of Notre Dame, Indiana
A realistically construed field version of Einstein's equations on a Minkowski background is considered. Derivations of Einstein's equations as a self-interacting ``spin 2'' field render the field interpretation natural. Recognition that a physical theory's content includes not only field equations, but also topology, boundary conditions, and a notion of causality implies that the field view has distinctive content from the geometrical theory. It is argued that the effective curved metric can be made to respect the flat metric's causal structure with sufficient generality. The effective dynamical metric then inherits global hyperbolicity from the background spacetime, so causal paradoxes involving black hole information loss or equal-time commutation relations do not arise. Evidently gravity can be consistently and realistically regarded as a universal force, while spacetime is flat. In this "moderately generally covariant" theory, absolute objects are absent from the field equations, yet do useful work in the theory.