Wormhole Basics

Abstract

Wormhole geometries are theoretical shortcuts in spacetime and are specific examples of solving the Einstein field equation in the reverse direction, namely, one first considers an interesting and exotic spacetime metric, and then finds the matter source responsible for the respective geometry. In this manner, it was found that some of these solutions possess a peculiar property, namely “exotic matter”, involving a stress–energy tensor that violates the null energy condition. These geometries also allow closed timelike curves, with the respective causality violations. In this chapter, we review the physical properties and characteristics of wormhole geometries. Furthermore, recent advances are presented on dynamic spherically symmetric thin-shell traversable wormholes. More specifically, a novel approach is considered by implicitly making demands on the equation of state of the matter residing on the transition layer, and demonstrates in full generality that the stability of thin-shell wormholes is equivalent to choosing suitable properties for the material residing on the thin shell.