Campos, AntonioCalzetta, Esteban A., 1958-Verdaguer Oms, Enric, 1950-2010-05-062010-05-0619970556-2821https://hdl.handle.net/2445/12308We consider the classical stochastic fluctuations of spacetime geometry induced by quantum fluctuations of massless nonconformal matter fields in the early Universe. To this end, we supplement the stress-energy tensor of these fields with a stochastic part, which is computed along the lines of the Feynman-Vernon and Schwinger-Keldysh techniques; the Einstein equation is therefore upgraded to a so-called Einstein-Langevin equation. We consider in some detail the conformal fluctuations of flat spacetime and the fluctuations of the scale factor in a simple cosmological model introduced by Hartle, which consists of a spatially flat isotropic cosmology driven by radiation and dust.10 p.application/pdfeng(c) The American Physical Society, 1997Relativitat (Física)GravitacióFísica estadísticaTeoria quànticaCosmologiaRelativity (Physics)GravitationCosmologyStatistical physicsQuantum theoryinfo:eu-repo/semantics/article115393info:eu-repo/semantics/openAccess