Light from distant galaxies is shifted toward longer wavelengths proportional to distance - the Hubble relation z = H₀d/c. This is one of cosmology's most robust observations. The standard interpretation: space is expanding, stretching photon wavelengths as they travel.
BFUT Paper 23 explains the redshift without expanding space.
Substrate Propagation Loss
A photon propagating through the Spaticle substrate at density ρ_s = 5.9 × 10⁻²⁷ kg/m³ interacts with the substrate continuously as it travels. Each interaction is extremely small - the substrate is very low density - but over cosmological distances the cumulative effect produces a measurable energy loss proportional to distance. The energy loss corresponds to a wavelength increase - a redshift. The redshift z ∝ d, matching the observed Hubble relation.
In BFUT, H₀ is not a measure of expansion rate. It is a measure of the substrate's photon energy loss rate - a function of ρ_s. H₀ is a property of the medium, not of cosmic geometry.
This Is Not Classical Tired Light
The classical "tired light" hypothesis proposed random scattering events that would blur and temporally smear distant sources - ruled out by supernova light curves showing no such smearing. BFUT's substrate energy loss is coherent and continuous - analogous to light slowing in a medium (refractive index) instead of random deflection. Coherent energy loss does not produce temporal smearing, consistent with the observations that excluded classical tired light.
The Falling H₀
BFUT's gravitational sorting framework (Paper 4) explains the Hubble relation primarily through the statistical properties of the surviving galaxy population, with substrate redshift as a component. Both accounts predict no universal expansion. Both predict that H₀ measured from different distance indicators will give systematically different values - the Hubble tension, which BFUT's Paper 1 derives as a natural consequence of the sorting framework instead of a crisis.
Download BFUT papers, simulation code, and companion materials: vijayshankarsharma.com/downloads/