ψ-Retention and the Stability of Cosmic Voids

Cosmic voids display remarkable geometric stability despite extreme matter depletion. This work introduces ψ-retention as a minimal, non-dynamical stability condition that preserves structural difference when dynamical drivers weaken. Within this framework, voids are reinterpreted as retentional geometries—domains in which form remains legible even as density approaches vanishing limits. The approach remains compatible with ΛCDM while clarifying the minimal requirements for the persistence of large-scale structure.