A small Universe

Abstract

Many cosmological models assume or imply that the total size of the universe is very large, perhaps even infinite. Here we argue instead that the universe might be comparatively small, in fact not much larger than the currently observed size. A concrete implementation of this idea is provided by the no-boundary proposal, in combination with a plateau-shaped inflationary potential. In this model, opposing effects of the weighting of the wave function and of the criterion of allowability of the geometries conspire to favour small universes. We point out that a small size of the universe also fits well with swampland conjectures, and we comment on the relation with the dark dimension scenario.

arXiv comment9 pages, 6 figures; v2: minor changes and references added, matches published version

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Cited by in corpus (4)

• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Conformal Cores of Quantum Black Holes in Quadratic Gravity
• Delicate curvature bounces in the no-boundary wave function and in the late universe
• Complex Saddles of Charged-AdS Gravitational partition function