A gentle introduction to the cosmological multiverse

Abstract

We give an introduction to the cosmological multiverse, aimed at an audience of artists. We discuss general relativity -- our modern theory of gravity -- and the cosmological constant, which is widely believed to be responsible for the observed accelerated expansion of the universe. We then turn to a big puzzle that the cosmological constant poses, and, eventually, how the multiverse could solve this puzzle. There's no such thing as a free lunch, however: the multiverse can become arbitrarily large and old. The unsolved problem of making unambiguous predictions for observations in eternally accelerating universes is known as the measure problem of eternal inflation.

arXiv commentAdapted transcript, translated to English, of a 30-minute talk given on October 3, 2024 at the arts and science workshop "La Mixtape du Multivers" (La Grange Center, Université de Lausanne) during the "Journées de recherche interdisciplinaires". Translations to Spanish, French, Dutch, Italian, German, Russian, Chinese, Arabic and Hindi (by Claude) are available as ancillary files