2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36412Stability and characterisitic geometrical and kinematical sizes of galaxies are strictly related to a minimal characteristic action whose value is of order $h$, the Planck constant. We infer that quantum mechanics, in some sense, determines the structure and the size of galaxies.6 pages, no figuresGeneral Relativity and Quantum Cosmologytext