2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/142968Whoever has to learn or to teach thermodynamics is confronted with conceptual difficulties which are specific to this field of physics ([1],[2]). It seems that they can be eliminated by inserting relativity in the thermodynamic theory. The aim of this paper is to summarize the problem and draw attention upon a fundamental point of the discussion.5 pages. (Submitted today to the American Journal of Physics)General Physicstext