A Compressible Vacuum Model of Gravity: Bridging Quantum Fields, Cosmology and Astrophysics

This work presents a unified Compressible Vacuum Model of Gravity (Pressure Driven Gravity, PDG) in which gravitational attraction arises from pressure gradients in a relativistic, compressible vacuum medium, potentially an axion Bose–Einstein condensate (BEC). The model bridges quantum field theory, astrophysics and cosmology, offering an alternative to spacetime curvature as described by General Relativity. It successfully reproduces classical gravitational tests in the Solar System, explains flat galaxy rotation curves without invoking dark matter, accounts for cosmic acceleration without a cosmological constant and proposes a rarefaction-wave mechanism for early-universe inflation.The framework employs a barotropic equation of state, with parameters grounded in axion-like particle theory and relativistic fluid dynamics. Across different applications, small variations in key parameters—such as the polytropic index, axion-like particle mass and vacuum density—reflect adaptations to specific physical regimes rather than inconsistencies. The model predicts measurable deviations from both the standard Lambda Cold Dark Matter (ΛCDM) model and General Relativity, including signatures in gravitational wave dispersion, cosmic microwave background patterns and large-scale structure evolution. These features make the theory both testable and highly relevant for near-term observational programs.