2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/101395The limits of the Second Law of Thermodynamics, which reigns undisputed in the macroscopic world, are investigated at the mesoscopic level, corresponding to spatial dimensions of a few microns. An extremely simple isolated system, modeled after Callen's adiabatic piston, [1] can, under appropriate conditions, be described as a self-organizing Brownian motor and shown to exhibit a perpetuum mobile behavior.17 pages, 4 figures. Revised versionClassical PhysicsGeneral Physicstext