Photonic Spacetime Fluid (Version 3)

We propose Photonic Spacetime Fluid Theory (PSFT), a speculative unificationframework in which all four fundamental forces emerge from a single mechanism: light, taken as the fundamental dynamical entity (the "prime mover"), drives the deformation of the spacetime manifold. Spacetime deformations propagate as a relativistic fluid governed by a covariant Navier-Stokes equation defined on the manifold itself, and matter arises as stable solitonic patterns within that fluid, trapped by its viscosity. We present two versions of the master equation. The original (v1) uses ascale-dependent scalar viscosity with smooth exponential suppression. Weidentify six experimental tensions with v1 and propose five structuralmodifications yielding the revised equation (v2), which features conformal (traceless) viscosity, a hard curvature gap via Heaviside activation, agauge-valued viscosity tensor encoding SU (3) (2) (1), Hall viscosity for parity violation, and universal gravitational coupling. We prove three main theorems: (1) ~in the inviscid limit, PSFT reproduces the Einstein field equations exactly (Theorem~12. 1) ; (2) ~the vorticity of the spacetime fluid in a Killing sector satisfies Maxwell's equations with U (1) gauge invariance inherited from the isometry (Theorem~9. 1) ; (3) ~in the high-viscosity regime at subnuclear scales, the theory produceslinear confinement with the correct QCD string tension (Theorem~10. 1). Wefurther derive parity violation and massive mediators for the weak interactionfrom the Hall viscosity term (Theorem~11. 1). We confront PSFT v2 with current experimental data including gravitationalwave observations (LIGO, GW170817, GW250114), solar system tests (CassiniPPN), equivalence principle bounds (MICROSCOPE, LLR), and recent cosmologicalanomalies (JWST, DESI). We identify six testable predictions and five honestlimitations. This is a theoretical exploration. We do not claim established physicalvalidity; rather, we develop the mathematical structure rigorously and examineits consequences. Version History: v3 (2026) Corrected the Hall viscosity line in the v2 master equation (Eq. 6. 9) to use the gauge-covariant divergence of the Hall stress; the previous form contained a vanishing index contraction. Disambiguated the symbol σA (gauge-algebra scalar order parameter) from σA₀₁ (gauge-sector shear tensor). Tightened the proof of Theorem 11. 1 (i) to derive parity-oddness directly from the axial-tensor nature of the Levi-Civita tensor. v2 (2026) Introduced the conformal viscosity, Heavisidecurvature gap, gauge-valued viscosity tensor, Hall viscosity and universalG modifications, resolving the six experimental tensions of v1 v1 (2026) Original formulation with Gaussian scale-dependentscalar viscosity and scale-dependent gravitational coupling