Action-at-a-Distance and Local Action in Gravitation: Discussion and Possible Solution of the Dilemma

The problem of the character of gravitation is approached by discussing three main possible modes of action from the historical, theoretical and empirical standpoints. The “Newtonian” mode of action-at-a-distance (AAAD)—in which Newton himself did not believe—is followed through three centuries, though the aim is not historical accuracy. This approach includes several Webertype theories of velocity-dependent action; these are found to be compatible with or transformable to the mode of the “material field local action” (MFLA). The historical roots of the mode of relativistic local action (RLA) are sketched, and it is criticized on both conceptual and empirical grounds. For the MFLA mode, a new theoretical framework is presented by giving a summary of equilibrium cosmology (EC) recently developed by the author. In EC, gravitation is an equilibrium process providing energy balance in systems of baryonic matter, while electromagnetic radiation is the contrary effect. Gravitation on a body is a pressure effect of gravitational quanta (gravitons) conducted from the background field by the gravitation field of the body. The formation of the field is outlined. Gravitons and photons interact via electrogravitational coupling (EGC), which causes the redshift effect and an analogous weakening of gravity, as well as the cosmic background radiation which is a re-emission equilibrium effect. From pressure-induced gravitation and EGC, a dynamical theory (EGD) can be constructed which unifies the gravitation effects in systems on different scales; until now, numerous ad hoc hypotheses had been nec essary to explain the effects.