Dual-Sector Cosmology from Structure-Driven Expansion: The Informational Actualization Model

Informational Actualization Model (IAM): Theoretical Derivation and Observational Validation

Heath W. Mahaffey — Independent Researcher, Entiat, Washington, USA

The Informational Actualization Model derives a specific prediction within the mu-Sigma modified gravity framework from four steps in established physics. Gravitational structure formation is the dominant source of quantum decoherence in cosmology. Each decoherence event carries a minimum thermodynamic cost kT ln2 at the cosmological horizon temperature (Landauer's principle). The resulting classical information is encoded on the cosmic horizon (holographic principle). This encoding modifies the entropy functional in the Jacobson-Cai-Kim thermodynamic derivation of the field equations. The modification applies exclusively to timelike degrees of freedom, because decoherence requires nonzero proper time, while null geodesics are unaffected.

These four steps yield mu(a) < 1 for matter perturbations and Sigma(a) = 1 for photon propagation with no free parameters. The activation function E(a) = exp(1 - 1/a) is derived from integrating the cumulative decoherence rate weighted by horizon thermodynamics. The coupling constant beta_m = Omega_m/2 follows from the virial partition of gravitational energy, verified against N-body-calibrated halo mass functions to 0.3%.

The model has been validated against the Planck 2018 CMB likelihood through 17 converged MCMC chains across two independent implementations: 12 chains using the MGCAMB mu-Sigma parametrization and 3 chains using direct modification of the CAMB Fortran perturbation equations implementing the physical dual-sector mechanism. Two additional exploratory runs applied the IAM term to the background expansion equation (modifying CAMB's dtauda function); these converged successfully and confirmed that the mechanism belongs at the perturbation level, not the background level. The Level 2 CAMB implementation confirms that sigma_8 suppression arises from genuine growth physics, with log(A_s) and Omega_m shifting less than 0.1-sigma between IAM and LCDM posteriors.

Principal results: delta-chi-squared = +0.02 relative to LCDM (posterior mean); sigma_8 suppression from 0.809 to 0.800; sector-dependent Hubble split with H0(photon) = 67.16 and H0(matter) = 72.26 km/s/Mpc, placing both Hubble tension endpoints within 1-sigma of observations without modifying the background expansion.

The unique signature mu < 1, Sigma = 1 is not predicted by any current modified gravity model in the literature. It is falsifiable: Euclid (projected 2027) is expected to detect or exclude the predicted amplitude at approximately 3-sigma. All chains, modified Fortran source, configuration files, and analysis scripts are publicly available at github.com/hmahaffeyges/IAM-Validation.