2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41393Two sides of cosmological constant problem are discussed: a mysterious compensation of all contributions to vacuum energy with the accuracy of 100-50 orders of magnitude and a surprising equality of a constant vacuum energy density to the present-day value of time dependent cosmological energy density.12 pages; contribution to M. Novello FestschriftHigh Energy Physics - Phenomenologytext