  The possibility that the multiverse corresponds to physical reality deserves
serious investigation. Having three different important theories,(quantum
mechanics, string theory and inflation), predict the existence of the
multiverse is hardly coincidental. I argue that the existence of the multiverse
must be expected from the underlying fundamental theory or else we can not
meaningfully address the puzzle of the initial conditions. In this view, the
extension of our current cosmology to a multiverse framework becomes an
extension of the Copernican principle to nature. In order to discuss the
ontology of the multiverse I propose to apply:
  - the principle of 'No Perpetual Motion' as a criterion for the parameter of
time; and,
  - the principle of 'Domains Correlations' as a criterion for determining the
background spacetime in which the multiverse is embedded.
