  We consider the question of properly defining energy and momenta for non
asymptotic Minkowskian spaces in general relativity. Only spaces of this type,
whose energy, linear 3-momentum, and intrinsic angular momentum vanish, would
be candidates for creatable universes, that is, for universes which could have
arisen from a vacuum quantum fluctuation. Given a universe, we completely
characterize the family of coordinate systems for which one could sensibly say
that this universe is a creatable universe.
