Gravitational lensing - the bending of light around massive objects - was one of the first confirmations of general relativity. Eddington's 1919 solar eclipse observation, Einstein rings, the lensing of galaxy clusters: these are among the most dramatic observational confirmations in the history of science.
General relativity describes lensing as the effect of curved spacetime on null geodesics. BFUT Paper 23 gives the substrate picture.
Substrate Deformation Refraction
In BFUT, a massive object deforms the surrounding Spaticle substrate - creating a density gradient in the medium of space. When a propagating substrate wave (light) enters a region of varying substrate density, it refracts - its direction of propagation changes in response to the density gradient. This is the same physical mechanism as refraction of light in a medium of varying refractive index, such as a glass lens or the atmosphere.
The angle of deflection predicted by BFUT matches the general relativistic prediction to leading order: for a light ray passing a distance b from a mass M:
This is twice the Newtonian prediction (which counts only the spatial curvature) because the substrate deformation affects both the spatial and temporal components of the photon's trajectory - consistent with the GR derivation.
Weak Lensing Without Dark Matter
The KiDS-1000 weak gravitational lensing survey measures the lensing convergence of galaxy clusters across stellar-mass bins. Dark matter models (NFW profile) achieve χ² = 5.77–6.57. The BFUT DD-1 substrate deformation model achieves χ² = 0.007–0.067. The BFUT model uses no dark matter and no per-cluster tuning - the same ρ_s that governs particle masses and galaxy rotation curves also governs gravitational lensing. The same substrate produces what general relativity describes as spacetime curvature, bends light, and generates the rotation curve support.
Download BFUT papers, simulation code, and companion materials: vijayshankarsharma.com/downloads/