Some unusual wormholes in general relativity

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 Lemaître–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. This article is part of the theme issue ‘The future of mathematical cosmology, Volume 1’.

From counterportation to local wormholes

“…While we envisage that future quantum gravity considerations could help unravel the physics of local wormholes, the general yet precise characterisation given already provides an explanatory framework for counterportation. Nonetheless, as geometrical conceptions rendering space disjunctly traversable [55] advance to encompass local wormholes, an experimental demonstration of counterportation (and therefore disjunct space traversability) would point not only to the existence in the lab of traversable wormholes, but conceivably of such geometry. We put forward finding a geometrical conception of counterportation as an open problem for the quantum gravity community.…”