First-Principles Derivation of the Isotropic Closure Factor: Aether-Unit Geometry, Closure Topology, and ₈ₒ₎ = 8{3} in QMU

This work completes the derivation of cosmological expansion scaling within the Aether Physics Model (APM) using Quantum Measurement Units (QMU) by providing a first-principles derivation of the isotropic closure factor. Previous papers established the expansion relation = Fq \, ₐ^4/5₈ₒ₎, the exponent 4/5 arises from the closure-measure ratio 8/5 associated with double-loxodromic transport geometry, and ₈ₒ₎ represents the isotropic normalization factor. While the exponent was derived from closure topology, the origin of ₈ₒ₎ had remained implicit. The present work derives\₈ₒ₎ = 83 from Aether-unit geometry and closure topology. The derivation begins with the total angular closure measure of a spherical orientation space, \ₒℂ d = 4, is normalized over the three independent volumetric closure axes to obtain the one-sided volumetric closure coefficient\ₕ₎₋ = 43. \ Closure transport is shown to be intrinsically bidirectional: each formation channel is paired with a return channel required by chronovibrational closure. This doubles the volumetric coefficient, yielding the isotropic closure factor\₈ₒ₎ = 2ₕ₎₋ = 83. \ The result demonstrates that ₈ₒ₎ is not an empirical parameter and not imported from Friedmann-type cosmology, but arises from the topology of closure flux across the Aether-unit boundary. It represents the geometric density parameter governing isotropic projection of closure imbalance. Substitution into the closure-density expansion law gives the fully determined QMU cosmological scaling relation = Fq \, ₐ^4/58{3}, no external normalization factors. Together with prior derivations of the Aether fine-structure parameter ₐ and the closure-measure exponent 8/5, this completes the internal QMU derivation of the Hubble expansion rate. The cosmological scaling is thus shown to emerge from closure geometry, closure topology, and QMU charge structure alone.