2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198047In a previous work [E.M. Prodanov, R.I. Ivanov, and V.G. Gueorguiev, Reissner-Nordstrom Expansion, Astroparticle Physics 27 (150-154) 2007], we proposed a classical model for the expansion of the Universe during the radiation-dominated epoch based on the gravitational repulsion of the Reissner-Nordstrom geometry - naked singularity description of particles that "grow" with the drop of the temperature. In this work we model the Universe during the Reissner-Nordstrom expansion as a van der Waals gas and determine the equation of state.13 pages, 2 figuresHigh Energy Physics - TheoryAstrophysicsGeneral Relativity and Quantum Cosmologytext