English

A small Universe

High Energy Physics - Theory 2024-02-05 v2 Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology

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.

Keywords

Cite

@article{arxiv.2309.03272,
  title  = {A small Universe},
  author = {Jean-Luc Lehners and Jerome Quintin},
  journal= {arXiv preprint arXiv:2309.03272},
  year   = {2024}
}

Comments

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

R2 v1 2026-06-28T12:14:38.971Z