Possible wormholes in a Friedmann universe

TL;DR

This paper investigates evolving wormholes within a closed Friedmann universe, analyzing their properties, lifespan, matter density, and traversability through numerical solutions of Einstein's equations.

Contribution

It provides explicit wormhole solutions in a Friedmann universe and examines their stability, lifespan, and traversability using numerical methods.

Findings

Wormhole throat lifetime is much shorter than the universe's lifetime.

Matter density near wormhole boundaries is lower than the universe's average.

Numerical analysis confirms wormhole traversability.

Abstract

We study the properties of evolving wormholes able to exist in a closed Friedmann dust-filled universe and described by a particular branch of the well-known Lema{\i}tre-Tolman-Bondi solution to the Einstein equations and its generalization with a nonzero cosmological constant and an electromagnetic field. Most of the results are obtained with pure dust solutions. It is shown, in particular, that the lifetime of wormhole throats is much shorter than that of the whole wormhole region in the universe (which coincides with the lifetime of the universe as a whole), and that the density of matter near the boundary of the wormhole region is a few times smaller than the mean density of matter in the universe. Explicit examples of wormhole solutions and the corresponding numerical estimates are presented. The traversability of the wormhole under study is shown by a numerical analysis of radial null geodesics.