The Hubble Tension as a Stellar Physics Bias in the Cosmological Braking Theory: Cepheid Period-Luminosity Relation in the Conformal Metric Φ (z) g_μν

In the Cosmological Braking Theory (CBT), matter propagates in the effective metric Φ (z) g_μν with Φ (z) = 1/D (z) ≥ 1 for z 0. Using standard stellar scaling laws in the conformal metric, we derive two systematic biases on Cepheid variables: (i) an increased pulsation period Pₑff = P₀ √Φ (zform), due to reduced mean density ρ̄ₑff = ρ̄₀/Φ; (ii) an increased luminosity Lₑff = L₀ Φ (zform) ², due to the mass-luminosity relation L ∝ M⁴. Both biases cause the local distance ladder to overestimate H₀ relative to the CMB value. The combined bias is ΔH₀/H₀ = 2. 562 × log₁₀ γ (zform), where γ (z) = 1/√D (z). For Cepheid host galaxies formed at zform = 2. 24 (consistent with the cosmic star-formation rate peak), this yields ΔH₀ = +6. 1 km/s/Mpc — exactly the observed Hubble tension. This constitutes a parameter-free, analytically derived resolution of the Hubble tension within CBT, requiring no new physics beyond the conformal coupling of matter to the EM condensate. The key observational test is a correlation between H₀ₐpparent and the stellar age of the Cepheid host galaxy, achievable with existing SH0ES data combined with stellar population age estimates.