  We apply the causal interpretation of quantum mechanics to homogeneous and
isotropic quantum cosmology where the sources of the gravitational field are
either dust or radiation perfect fluids. We find non-singular quantum
trajectories which tends to the classical one when the scale factor becomes
much larger then the Planck length. In this situation, the quantum potential
becomes negligible. There are no horizons. As radiation is a good approximation
for the matter content of the early universe, this result suggests that the
universe can be eternal due to quantum effects.
