Many worlds in one

TL;DR

The paper discusses the implications of inflationary cosmology, proposing that our infinite universe contains countless regions with identical histories up to now, resembling a multiverse but with real, not just theoretical, regions.

Contribution

It introduces a framework where infinite regions of the universe have finite possible histories, linking cosmological inflation to a multiverse concept with real, distinct regions.

Findings

Finite possible histories per region from recombination to now.

Infinite regions with identical pasts but potentially different futures.

All non-forbidden histories occur in a finite fraction of regions.

Abstract

A generic prediction of inflation is that the thermalized region we inhabit is spatially infinite. Thus, it contains an infinite number of regions of the same size as our observable universe, which we shall denote as $\O$-regions. We argue that the number of possible histories which may take place inside of an $\O$-region, from the time of recombination up to the present time, is finite. Hence, there are an infinite number of $\O$-regions with identical histories up to the present, but which need not be identical in the future. Moreover, all histories which are not forbidden by conservation laws will occur in a finite fraction of all $\O$-regions. The ensemble of $\O$-regions is reminiscent of the ensemble of universes in the many-world picture of quantum mechanics. An important difference, however, is that other $\O$-regions are unquestionably real.