Seminário 20/08

Na próxima sexta-feira, dia 20/08 às 10h, teremos o seminário de Tays Miranda (Universidade de Helsinki, Finlândia) intitulado: "Quantum fluctuations in contracting cosmologies"

Link: https://us02web.zoom.us/j/87309346620?pwd=YzdCLzJCRVhkb0tuSGJiV1dHSk9pUT09

Título: Quantum fluctuations in contracting cosmologies

Resumo: The goal of this seminar is to discuss how quantum field fluctuations give rise to stochastic noise in a cosmological model described by a scalar field with an exponential potential. In particular, we compute these quantum fluctuations in an inflating or contracting cosmology and show how they perturb the equation of state on large scales, which can lead to a quantum instability of the classical collapse solution, below the Planck scale in the case of a pressureless collapse. Also we show that although there is a gauge correction to the amplitude of the stochastic noise, since in principle field perturbations are written in a different gauge than stochastic equations, they are negligible for the slow-roll inflation, ekpyrotic collapse and pressureless collapse, which assures that the stochastic formalism is suitable for describing quantum fluctuations in the early universe.