An inflationary cosmology from anti-de Sitter wormholes

Abstract

We propose a new type of wavefunction for the universe computed from the Euclidean path integral, with asymptotically $AdS$ boundary conditions. In the semiclassical limit, it describes a Euclidean (half)-wormhole geometry, exhibiting a local maximum of the scale factor at the surface of reflection symmetry, giving rise to an expanding universe upon analytic continuation to Lorentzian signature. We find that these Euclidean wormholes set natural initial conditions for inflation and that the semi-classical Wheeler-DeWitt wavefunction can favor a long lasting inflationary epoch, resolving a well known issue of the no-boundary proposal. Due to the asymptotic $AdS$ conditions in the Euclidean past they raise the possibility of describing the physics of inflating cosmologies and their perturbations within the context of holography.