2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/101866We prove a global result in time for the initial value problem for the relativistic Boltzmann equation on the flat Robertson-Walker sapace time, in the functional framework appropriate to the coupling with Einstein's equations. We had nowhere to restrict the size of the initial data which can hence be taken arbitrarily large.General Relativity and Quantum Cosmologytext