Some unusual wormholes in general relativity

TL;DR

This paper reviews recent models of traversable wormholes in general relativity, including rotating cylindrical, cosmological, and higher-dimensional wormholes, expanding our understanding of their properties and potential observability.

Contribution

It introduces new wormhole solutions in four and six dimensions that challenge traditional notions, including models without exotic matter and with unique topological features.

Findings

Rotating cylindrical wormholes can exist without exotic matter.

Cosmological wormholes connect different Friedmann universes.

Six-dimensional wormholes link worlds with different extra-dimensional properties.

Abstract

In this short review we present some recently obtained traversable wormhole models in the framework of general relativity (GR) in four and six dimensions that somehow widen our common ideas on wormhole existence and properties. These are, first, rotating cylindrical wormholes, asymptotically flat in the radial direction and existing without exotic matter. The topological censorship theorems are not violated due to lack of asymptotic flatness in all spatial directions. Second, these are cosmological wormholes constructed on the basis of the Lemaitre-Tolman-Bondi solution. They connect two copies of a closed Friedmann world filled with dust, or two otherwise distant parts of the same Friedmann world. Third, these are wormholes obtained in six-dimensional GR, whose one entrance is located in "our" asymptotically flat world with very small extra dimensions while the other "end" belongs to a universe with large extra dimensions and therefore different physical properties. The possible observable features of such wormholes are briefly discussed.