FENS Seminar: Cosmological Evolution of Vacuum and Cosmic acceleration

Physics Seminar, 5 Jan 2011, Wednesday, 13:40, FENS L045

Dr. Ali Kaya
Boğaziçi Üniversitesi

Title: Cosmological evolution of vacuum and cosmic acceleration

Abstract: We study the cosmological impact of a free massless quantum scalar field in a Friedmann-Robertson-Walker space-time. Assuming that the scalar is placed in
its ground state, a simple expression for the stress-energy-momentum tensor is
obtained using adiabatic regularization. We show that vacuum energy density
grows from zero up to the fourth power of the Hubble parameter in about one
Hubble time, vacuum fluctuations give positive acceleration and they can
completely alter the cosmic evolution of the universe dominated otherwise by
cosmological constant, radiation or pressureless dust.