CAN GALACTIC OBSERVATIONS BE EXPLAINED BY A RELATIVISTIC GRAVITY THEORY

We consider the possibility of an alternative gravity theory explainin g the dynamics of galactic systems without dark matter. From very gene ral assumptions about the structure of a relativistic gravity theory w e derive a general expression for the metric to order (v/c)(2). This a llows us to compare the predictions of the theory with various experim ental data: the Newtonian limit, light deflection and retardation, rot ation of galaxies, and gravitational lensing. Our general conclusion i s that the possibility for any gravity theory to explain the behavior of galaxies without dark matter is rather improbable.