Resumo
In this notes we discuss an approach used to solve the Wheeler-DeWitt equation in quantum cosmology,
which consist in discard a sector of frequencies solutions (say negative) with foundation in
a certain super-selection rule. In a preliminary analysis, we point well known results in relativistic
quantum field theory, showing that the approach of super-selection, does not lead to acceptable
results. In the area of quantum cosmology, we show that by discarding solutions of negative frequencies,
important processes are lost, namely the existence of cyclic solutions which, under certain
reasonable assumptions, can be interpreted as processes of creation-annihilation at the Planck scale,
which are typical of any relativistic quantum field theory.