Can extra dimensional effects allow wormholes without exotic matter?

TL;DR

This paper investigates whether extra-dimensional effects in scalar-tensor gravity theories can support Lorentzian wormholes without requiring exotic matter, suggesting a link to warped extra dimensions like in Randall-Sundrum models.

Contribution

It demonstrates that in scalar-tensor theories, certain wormholes can exist with non-exotic matter due to effective geometric stress energy from extra dimensions.

Findings

On-brane matter can satisfy the Weak Energy Condition in some wormholes.

Effective geometric stress energy from extra dimensions supports wormhole stability.

Potential observational evidence for extra dimensions if wormholes are found.

Abstract

We explore the existence of Lorentzian wormholes in the context of an effective on-brane, scalar-tensor theory of gravity. In such theories, the timelike convergence condition, which is always violated for wormholes, has contributions, via the field equations,from on-brane matter as well as from an effective geometric stress energy generated by a bulk-induced radion field. It is shown that, for a class of wormholes, the required on-brane matter, as seen by an on-brane observer in the Jordan frame, is not exotic and does not violate the Weak Energy Condition. The presence of the effective geometric stress energy in addition to on-brane matter, is largely responsible for creating this intriguing possibility. Thus, if such wormholes are ever found to exist in the Universe, they would clearly provide pointers towards the existence of a warped extra dimension as proposed in the two-brane model of Randall and Sundrum.