Lesagian Gravity Redux?

The old Le Sage’s hypothesis on the corpuscular origin of gravity is revisited. The discussion is developed along three lines: the "modern" wave approach, a "mass–flux" model of a relativistic fluid, and the traditional corpuscular model. The predictions obtained in all the three approaches are convergent with other current attempts. The main outcomes are the emergence of a maximal gravitational acceleration – compatible with the surface gravity of neutron stars – and the absence of gravitational field divergences for arbitrarily large or collapsed masses. The resulting theory differs from classical Newtonian gravity in its much clearer separation between the concepts of heavy mass and inert mass, a distinctive characteristic of the Le Sage-type (or “shadow gravity” or “Push–Gravity” (PG)) theories. The price to pay is the abandonment of the equivalence principle in its weak form, which might no longer be considered rigorously valid. We will only touch on the issue of experimental verification, which remains very difficult: the simple test we propose here is a rough estimate of gravity at the Earth’s equator and poles using PG theory, which indicates only qualitative agreement with experimental data. In this version, the section “XVII. NEWTONIAN VS RELATIVISTIC EFFECTS OF GRAVITY” has been added and small changes have been made here and there to the text and the bibliography. Finally, a cosmological speculation based on Le Sage’s idea is sketched, which is discussed at a preliminary and tentative level.