2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/113237It is proved that density plays a crucial role in the structure of quantum field theory. The Dirac and the Klein-Gordon equations are examined. The results prove that the Dirac equation is consistent with density related requirements whereas the Klein-Gordon equation fails to do that. Experimental data support these conclusions.12 pages, no figureQuantum Physicstext