Inferring External Cosmic Structure from Horizon Formation Mechanisms

This paper introduces a horizon inversion principle for cosmology: rather than speculating about what lies beyond observational horizons, it infers admissible global cosmic structures by analyzing the mechanisms that generate horizons themselves. Causal, topological, and informational horizons are treated as diagnostic artifacts whose formation mechanisms impose invariant constraints on otherwise unobservable regions. By identifying propagation–change mismatches that give rise to horizons, the framework maps empirical observables—such as cosmic microwave background (CMB) correlations, topology null results, and horizon-scale information bounds—to constrained classes of global completions. The approach integrates geometry, topology, and quantum information theory while remaining empirically grounded and falsifiable, avoiding speculative extensions beyond tested physics. Illustrative applications incorporate recent observational developments, including strengthened CMB constraints on non-orientable manifolds and lens spaces, persistent Hubble tension measurements, and advances in horizon-based quantum information. Explicit mathematical modeling via eigenmode decompositions and correlation matrices demonstrates how horizon mechanisms restrict admissible external structures and how future null results can further exclude entire classes of global cosmologies. This work reframes cosmological horizons not as epistemic limits, but as inverse probes of global structure, providing a conservative, mechanism-based pathway for inferring large-scale cosmic organization.