Paper LXXVII established that gravitational potentials modify the eec- tive coupling constants through brane-fabric refraction, with sector-dependent shifts δ(1/αi) = (λi/2π)Φ/c2. We now derive the consequences for the observed redshift of spectral lines, for the Hubble tension, and for gravitational lensing. (1) A third red- shift term. Standard spectroscopy decomposes observed redshift into cosmological (zcos) and gravitational (zgrav) contributions. The Fano coupling refraction adds a third term: zrefrac,i = −(λi/π) Φ/c2, which is 1/π ≈32% of the standard gravitational redshift for EM lines, and 7/π ≈2.23× the standard gravitational redshift for QCD-sensitive molecular lines. This third term has been absent from all standard spectroscopic analysis and is currently absorbed implicitly into the gravitational redshift budget. (2) AGN broad-line excess redshift. Quasar broad-line regions (BLR) have Lorentz-prole emission lines that are systematically redshifted relative to the narrow-line region (NLR) by ∼5002000 km/s. Standard explanations invoke inow/outow velocities. For a typical AGN BLR at Φ/c2 ≈−10−3, the Fano refraction contribution to the BLR-NLR oset is ∼300 km/s (∼30% of the observed oset), and the QCD-sensitive molecular lines near the BLR would show an additional ∼670 km/s of refraction-induced red- shift. (3) The Hubble tension: partial contribution, not the main mechanism. We show that gravitational refraction between the Cepheid calibration environment (LMC/MW, Φ/c2 ∼−10−6) and SNIa host galaxies (Φ/c2 ∼−10−4) produces a bias in Hlocal 0 of order 0.0010.1 km/s/Mpc. This goes in the correct direction (increases local H0) but is 23 orders of magnitude too small to explain the 5.8 km/s/Mpc tension. The main Hubble tension mechanism in the framework remains the δM/M asymmetry tilt driving a T1/T2 viscosity gradient between the global sump and local cluster envi- ronment (Papers XXXV, XXXVI). Gravitational refraction provides a small (≲0.1%) perturbative correction to this. (4) Gravitational chromatic aberration. Dier- ent Fano sectors accumulate dierent phase shifts during gravitational lensing, because the eective refractive index depends on λi. Strong lensing arcs from galaxy clusters (Φpeak/c2 ∼−5 × 10−4) produce an angular splitting between EM-sensitive and QCD- sensitive emission of δθ ∼500 µas. This is below current Gaia precision but potentially detectable with VLBI combined with future sub-µas astrometry. Four new predictions follow... Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.
Bharathi Jagadeesan (Fri,) studied this question.