  Our knowledge of the equation of state of the quark gluon plasma has been
continuously growing due to the experimental results from heavy ion collisions,
due to recent astrophysical measurements and also due to the advances in
lattice QCD calculations. The new findings about this state may have
consequences on the time evolution of the early Universe, which can estimated
by solving the Friedmann equations. The solutions of these equations give the
time evolution of the energy density and also of the temperature in the
beginning of the Universe. In this work we compute the time evolution of the
QGP in the early Universe, comparing several equations of state, some of them
based on the MIT bag model (and on its variants) and some of them based on
lattice QCD calculations. Among other things, we investigate the effects of a
finite baryon chemical potential in the evolution of the early Universe.
