Gravitational Lensing in USP Field Theory: From Atomic Refraction to Galactic-Scale Resonance Gradients ( msf:49800 )

Gravitational lensing is commonly described as the bending of light along curved spacetime geodesics. While this geometric formulation reproduces observations, it does not identify a direct physical interaction mechanism between light and mass. This standalone paper reformulates gravitational lensing as a refraction phenomenon driven by resonance gradients within USP Field Theory. By first examining light propagation in atomic and material media, the work builds a continuous physical bridge from ordinary refractive optics to planetary, stellar, and galactic-scale lensing. In the USP framework, light follows gradients in frequency mismatch (Δf) rather than spacetime curvature as a physical entity. The paper demonstrates how this mechanism reproduces standard lensing phenomenology while predicting potential frequency- and coherence-dependent signatures under extreme field gradients. An appendix extends the model with quantitative relations, spectral deformation effects, and a roadmap for observational tests using multi-band lensing data (e.g., JWST). The document is designed to be fully standalone while remaining compatible with future theoretical and experimental upgrades.