GETT Correspondence Series Paper 5: Gravitational Lensing Across Regimes: Mass, Voids, and Density-Conditioned Deflection

Gravitational Lensing Across Regimes: Mass, Voids, and Density-Conditioned DeflectionGETT Correspondence Series: Domain-Limit Reconstruction of Physics (GCS-DLRP) Paper 5 A unified density-regulated framework for photon lensing across overdense and underdense regimes, linking gravitational and propagation behaviour through a single scalar-field mechanism... Gravitational lensing is one of the most successful predictive frameworks of General Relativity, accurately describing light deflection across a wide range of astrophysical scales. However, its standard formulation is geometric and does not provide a single unified physically causal propagation framework spanning both overdense and underdense environments. This paper develops a correspondence and extension framework within General Expanse Tension Theory (GETT), in which photon propagation is treated as a density-regulated interaction with a real, all-pervading scalar field (the Holland Field, Φ). Within the Einstein Domain, the formalism reproduces all established gravitational lensing phenomena, including strong lensing, weak lensing, microlensing, convergence, shear, and time-delay behaviour. Beyond this domain, the framework extends naturally to low-density, transition, and mixed line-of-sight regimes. A series of worked examples demonstrates how void lensing, cluster residuals, environmental dependence, and path-history effects arise within a single propagation framework. The paper then performs a cross-domain consistency test by mapping the full set of photon-lensing phenomena onto the independently derived matter-dynamics density architecture established in Paper 4.4. The results show a systematic alignment in characteristic density ordering between gravitational behaviour and photon propagation regimes. This alignment is non-trivial: the two structures are derived independently, and no prior requirement exists for their correspondence. Notably, existing observational indications—such as environment-dependent weak lensing, void profile sensitivity, and line-of-sight corrections in time-delay cosmography—are directionally consistent with the predicted behaviour. The paper consolidates its predictions in Appendix J and provides a preliminary mapping to current observational literature in Appendix K, establishing a structured, testable programme for empirical evaluation across all density regimes. If sustained under further observational testing, these results suggest that gravitation and photon propagation may share a common density-regulated physical basis, and that their apparent separation within standard formulations reflects a domain-limited description rather than a fundamental distinction. Keywords gravitational lensing, weak lensing, strong lensing, microlensing, cosmic voids, void lensing, line-of-sight effects, photon propagation, General Relativity, scalar field theory, modified gravity, cosmology, dark matter alternatives, dark energy alternatives, cosmic web, galaxy clusters, time-delay cosmography, density dependence, Higgs portal, GETT, General Expanse Tension Theory, Holland Field A unified density-regulated framework for photon lensing across overdense and underdense regimes, linking gravitational and propagation behaviour through a single scalar-field mechanism.