2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57010We give an overview on a couple of recent results concerning the KMS-condition and the characterization of thermodynamic equilibrium states from a moving observer's point of view. These results include a characterization of vacuum states in relativistic quantum field theory and a general derivation of the Unruh effect.9 pages, talk given at the Conference OAMP 2001 at Constanta, RomaniaMathematical Physicstext