Evolution of Cosmological Horizons of Wormhole Cosmology

TL;DR

This paper explores the evolution and properties of cosmological horizons in wormhole cosmology, analyzing their geometric and causal structures across different universe models, and examining implications for light cones and particle horizons.

Contribution

It provides an exact solution for wormhole cosmology, investigates the dynamic behavior of apparent horizons, and discusses the causal structure and horizon properties in multi-component universes.

Findings

Apparent horizons' speeds differ from standard cosmology.

Wormholes alter the structure of past light cones and particle horizons.

Travel-through-wormholes can connect distant or separate universes.

Abstract

Recently we solved the Einstein's field equations to obtain the exact solution of the cosmological model with the Morris-Thorne type wormhole. We found the apparent horizons and analyzed their geometric natures, including the causal tructures. We also derived the Hawking temperature near the apparent cosmological horizon with a proper definition of the Kodama vector. In this paper, we investigate the dynamic properties of the apparent horizons according to the distribution of cosmic matter. The matter-, radiation-, and lambda-dominated universes are considered as a single component universe. As a multi-component universe, we adopt the $\Lambda$CDM universe which contains the matter and lambda. We also considered the speeds of apparent horizons and compared them with those of the universe without wormhole. The past light cone and the particle horizon is examined for what happens in the case of model with wormhole. Since the spatial coordinates of the spacetime with the wormhole are limited outside the throat, the past light cone can be operated by removing the smaller-than-wormhole region. The past light cones without wormhole begin start earlier than the past light cones with wormhole in conformal time-proper distance coordinates. The travel-through-wormhole can shows different part from normal one. Therefore, the particle horizon distance determined from the observer's past light cone can not be defined in a unique way. The case of the travel-through-wormhole can be extended into another universe or far distant causally disconnected region.