  In this paper, we analyse the Wheeler-DeWitt equation in the third quantized
formalism. We will demonstrate that for certain operator ordering, the early
stages of the universe are dominated by quantum fluctuations, and the universe
becomes classical at later stages during the cosmic expansion. This is
physically expected, if the universe is formed from quantum fluctuations in the
third quantized formalism. So, we will argue that this physical requirement can
be used to constrain the form of the operator ordering chosen. We will
explicitly demonstrate this to be the case for two different cosmological
models.
