  Certain closed-universe big-bang/big-crunch cosmological spacetimes may be
obtained by analytic continuation from asymptotically AdS Euclidean wormholes,
as emphasized by Maldacena and Maoz. We investigate how these Euclidean
wormhole spacetimes and their associated cosmological physics might be
described within the context of AdS/CFT. We point out that a holographic model
for cosmology proposed recently in arXiv:1810.10601 can be understood as a
specific example of this picture. Based on this example, we suggest key
features that should be present in more general examples of this approach to
cosmology. The basic picture is that we start with two non-interacting copies
of a Euclidean holographic CFT associated with the asymptotic regions of the
Euclidean wormhole and couple these to auxiliary degrees of freedom such that
the original theories interact strongly in the IR but softly in the UV. The
partition function for the full theory with the auxiliary degrees of freedom
can be viewed as a product of partition functions for the original theories
averaged over an ensemble of possible sources. The Lorentzian cosmological
spacetime is encoded in a wavefunction of the universe that lives in the
Hilbert space of the auxiliary degrees of freedom.
