2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56405We consider vacuum quantum effects in the Early Universe, which may lead to inflation. The inflation is a direct consequence of the supposition that, at high energies, all the particles can be described by the weakly interacting, massless, conformally invariant fields. We discuss, from the effective field theory point of view, the stability of inflation, transition to the FRW solution, and also possibility to study metric and density perturbations.6 pages, LaTeX, no figures. Contribution to the Proceedings of the X Jorge Andre Swieca school in Particles and Fields. To be published in World ScientificHigh Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext