Nonlinear non-relativistic gravity

A phenomenological theory of gravitation is proposed, based on a pre-relativistic approach to electromagnetism. The general relativistic, purely geometric, spacetime conception is criticized. Space itself is assumed to have physical substance. This substance, the ether, manifests by its permeability. Gravitational fields do not curve space, but rather distort the ether, and so affect its permeability. The permeability determines the speed of light, which is varying as in a dielectric medium. The theory is only in certain limits Lorentz invariant; the concept of a uniformly moving observer is likewise only approximate, and so is the principle of equivalence. Nonlinear field equations for the scalar gravitational field as well as the permeability tensor of the ether are constructed in a way to fit the classical experiments on gravitation. Estimates on the variation of the speed of light in our solar system are given. (C) 1998 Elsevier Science Ltd. All rights reserved.