2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/30971This article aims at clarifying the language and practice of scientific experiment, mainly by hooking observability on calculability.19 pages LaTeX article (uses some pstricks) thorough revision 2 see also http://pierre.albarede.free.frArtificial IntelligenceI.2.4;I.2.6text