2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/83129Decaying states can be represented by Gamow vectors with an exponential, asymmetric time evolution. This asymmetric evolution is a manifestation of irreversibility on the microphysical level. The Rigged Hilbert Space provides a mathematical theory.15 pages latex. XXII Symposium on Nuclear Physics, Oaxtepec, Mexico, January (1999)Nuclear TheoryMathematical Physicstext