General Relativity (GR) has successfully described gravitational phenomena using geometric language, yet it leaves two fundamental physical blind spots: What is the physical constitution of curved spacetime? And why is gravity so difficult to unify with the other fundamental forces (Standard Model)? This paper proposes the Object Field Density Equilibrium (OFDE) theory as a Macroscopic Effective Field Theory (EFT) of GR. Building upon our foundational work on the ”Illusion of Gravity” 1, we propose that the geometric curvature of GR is the macroscopic manifestation of the density gradient of a Vacuum Superfluid. The speed of light is treated as the wave speed within this vacuum medium, governed by the constitutive relation c(ρ) ∝ ρ−1/2. By introducing a linear response equation of state for the vacuum’s reaction to matter energy, we derive the Earth’s standard density gradient ∇ρ ≈ 2.18×10−16 m−1. This parameter not only precisely reproduces observations from GPS, optical lattice clocks, and Shapiro delay, but also unifies gravitational redshift and optical refraction as v ariable-density medium effects. The core thesisof OFDE is that the so-called ”curvature of the time dimension” is essentially a physical dynamic manifestation of the microscopic world (particle oscillation) being affected by the vacuum field density. OFDE constructs the missing physical ontology for General Relativity and provides theoretical possibilities for manipulating gravity via Vacuum Density Engineering (VVE), including the potential for Artificial Spacetime Curvature and BiologicalLife Extension.
Wayne Ji (Sun,) studied this question.