2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179396We examine whether the cosmologies with varying speed of light (VSL) are compatible with the second law of thermodynamics. We find that the VSL cosmology with varying fundamental constant is severely constrained by the second law of thermodynamics, whereas the bimetric cosmological models are less constrained.15 pages, LaTeX, Revised version with minor corrections to appear in Phys. Rev. DHigh Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext