2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16990We discuss a theoretical approach to structural glasses as they happen in real situations. Older ideas based on `configurational entropy', on `fictive temperatures' and on Edwards' `compactivity' are sharpened and unified in an out of equilibrium context. The picture is such that it may be supported or disproved by an experimental test, which we describe.To be published in the special issue `Physics of Glasses' of the Comptes Rendus de Physique de l'Academie des SciencesStatistical Mechanicstext