A Collapse–Rebound Mechanism for the Formation of Large-Scale Cosmic Voids

A Collapse–Rebound Mechanism for the Formation of Large-Scale Cosmic Voids This preprint develops a theoretical cosmology framework that explores an alternative formation pathway for certain large-scale cosmic voids. While the standard ΛCDM model primarily attributes void evolution to the gravitational growth of primordial underdensities, some observed characteristics—such as sharp density transitions, coherent outward velocity fields, and exceptionally large void scales—indicate that additional nonlinear dynamical processes may be relevant. The study proposes that some voids may originate from regions that initially experience gravitational compression due to surrounding overdensities, followed by a rebound-driven expansion phase that dynamically evacuates matter outward. This collapse–rebound evolution can deepen the void interior, establish dense surrounding walls, and generate structural behavior consistent with selected observational features. The framework outlines the conceptual stages of compression, nonlinear transition, rebound expansion, and stabilization. It further identifies expected observational indicators, including sharper radial density gradients, coherent velocity structures, and distinct developmental timelines. The model remains consistent with ΛCDM cosmology while offering an extended evolutionary pathway rather than replacing existing theory. This preprint establishes a foundation for continued development through analytical modeling, large-scale simulations, and comparison with present and forthcoming datasets such as SDSS, DESI, Euclid, and LSST.