Electromagnetic-Thermodynamic Foundations of Gravity: Variable G from Vacuum Gradients

We advance a thermodynamic-electromagnetic account of gravitation in which the gravitational coupling becomes an effective field Geff(r) set by gradients of the vacuum free-energy density shaped by matter, boundaries, and electromagnetic (EM) fields. In weakly inhomogeneous environments, Geff differs from the laboratory constant G0 only at the 10−10 −10−8 level, but these deviations are predictive and testable across altitude changes, shielded cavities, and controlled EM energy environments. I formalize the framework (thermodynamic gravity, TGH; and its quantum extension, Q-TGH) by (i) writing a covariant free-energy functional for the vacuum, (ii) deriving the modified Poisson equation and the post-Newtonian (PN) limit, and (iii) showing that light bending, gravitational redshift and perihelion precession reduce to the usual GR results when vacuum inhomogeneities are negligible, while permitting small, environment-correlated offsets in G. I also propose a multi-site, atom-interferometric determination of Geff with co-located EM diagnostics, and discuss falsifiable signatures that distinguish TGH/Q-TGH from metric-only modifications.