The Interior Observer Cosmological Framework: A Black Hole Cosmology with the CMB as Event Horizon Radiation

A cosmological framework proposing that the observable universe exists inside a Schwarzschild black hole, with the cosmic microwave background as interior Hawking radiation. The geometric boost factor γ = √ (rₛ/lP) resolves the 30-order-of-magnitude temperature gap. Einstein-Cartan-Holst torsion generates dark energy. Core predictions require zero free parameters: TCMB = 2. 663 K (2. 3% error), ρ_Λ = 6. 05 × 10⁻²⁷ kg/m³ (1. 5% error), a₀ = 1. 345 × 10⁻¹⁰ m/s² (12% error), H₀ = 58. 4 km/s/Mpc (predicted). Confrontation with DESI DR1 BAO data, with H₀ as a single fitted parameter, yields χ² = 7. 57 (AIC = 9. 57) versus ΛCDM χ² = 8. 83 (AIC = 14. 83, three free parameters) — the IO geometric expansion history is statistically preferred. Developed through human-AI collaboration. v3. 4 correction note: v3. 2 reported χ² = 15. 1 at zero free parameters. Paper 3 identified two errors: (1) the Ωₖ normalization used a = rₛ instead of the correct a = RU, shifting Ωₖ from −0. 057 to −0. 130; (2) the DESI comparison used DV/rd at all redshifts, but data at z ≥ 0. 510 reports DM/rd. Both errors independently verified by Gemini. Core predictions (TCMB, ρ_Λ, a₀, γ derivation) are completely unaffected. v3. 4 additionally corrected Paper 1 Table 2 values (H₀ 58. 5→58. 4, Ω_Λ 0. 919→0. 933) and standardized decimal precision across all constants. See Paper 3 for full correction analysis. Three changes: TCMB 2. 66→2. 663, a₀ 1. 35→1. 345, and the correction note updated from v3. 3 to v3. 4 with the Table 2 and precision fixes documented. Everything else unchanged and consistent with Paper 3 v1. 3. Paper 4 status: All four core predictions from Paper 1 are verified and extended in Paper 4. The ρ_Λ derivation is confirmed via two independent routes, recovering the Barbero-Immirzi parameter γBI to 2. 9% of the LQG value (25/25 SymPy checks). The MOND scale a₀ = c²/rₛ is confirmed as a zero-parameter prediction; the interpolation function μ (a/a₀) is identified as requiring quantum gravity completion. Paper 1 §6. 4's claim that w = −1 is confirmed by CAMB (w = −1/3 ruled out at χ² = 716). Structure formation is proven viable: the OS dust clusters gravitationally, identifying dark matter as the interior geometry itself. The CMB first acoustic peak is predicted at ℓ₁ ≈ 180 (Planck: 220), an 18% tension driven by Ωₘ h² = 0. 067, which is the framework's most significant open problem. Paper 1 Open Questions #1–5 are all addressed in Paper 4. Companion to Paper 2 (DOI: 10. 5281/zenodo. 18868612), Paper 3 (DOI: 10. 5281/zenodo. 18876346), Paper 4 (DOI: 10. 5281/zenodo. 18883069), Paper 5 (DOI: 10. 5281/zenodo. 18889865), and Paper 6 (DOI: 10. 5281/zenodo. 18891475).