Classical and quantum cosmology with two perfect fluids: stiff matter
  and radiation
  In this work the homogeneous and isotropic Universe of
Friedmann-Robertson-Walker is studied in the presence of two fluids: stiff
matter and radiation described by the Schutz's formalism. We obtain to the
classic case the behaviour of the scale factor of the universe. For the quantum
case the wave packets are constructed and the wave function of the universe is
found.
