2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54702The free energy due to the vacuum fluctuations of matter fields on a classical gravitational background is discussed. It is shown explicitly how this energy is calculated for a non-minimally coupled scalar field in an arbitrary gravitational background, using the heat kernel method. The treatment of (self-)interacting fields of higher spin is outlined, using a meanfield approximation to the gaugefield when treating the gauge boson self interaction and the fermion-gauge boson interaction.LaTeX, 16 pages, appears in Proceedings of the 3rd International Alexander Friedman Seminar on Gravitation and Cosmology, Friedman Lab. Press, St. Petersburg 1995High Energy Physics - Theorytext