Generalization of the Hoyle-Narlikar theory and connection between electromagnetism and gravitation in the generalized theory

A generalization of the Hoyle-Narlikar theory is proposed, allowing for inclusion of electromagnetism into the scheme of this theory. This is carried out by modifying the equation for the scalar Green function. Electromagnetism is considered as direct particle interaction which is known to be equivalent to field electrodynamics from the viewpoint of experimentally observable results. The resulting generalized theory reduces to general relativity (GR) and to conventional electrodynamics in Minkowski space in the corresponding limiting cases. In the general case electromagnetism and gravitation turn out to be connected with each other in a nontrivial way which is of interest for further investigation.