2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/136711Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is presented. By considering the standard big bang model, it is shown how the recent results of Prigogine et alii \cite{1} can be recovered and, at the same time their limits of validity are explicited.8 pages, no figuresAstrophysicstext