Résumé |
In the context of inflationary cosmology a natural question arises on
what precedes inflation itself. We review aspects of the Hartle-Hawking (no
boundary) and Vilenkin (tunneling) proposals, and their relation to the Wheeler-
DeWitt equation.
These raise some paradoxes that are complementary in nature and in clash with
observations.
On the other hand theories of quantum gravity are better defined in the presence
of a negative cosmological constant. I will propose a new type of wave function of
the universe
with asymptotically AdS boundary conditions in the far (Euclidean) past.
In the semiclassical limit, it describes a Euclidean (half)-wormhole geometry with
properties that result in an expanding universe upon analytic continuation to
Lorentzian signature.
In this context some of the aforementioned phenomenological issues can be
resolved.
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