Wormholes, the weak energy condition, and scalar-tensor gravity

TL;DR

This paper constructs a class of traversable Lorentzian wormholes in scalar-tensor gravity where the matter satisfies the weak energy condition, linking their existence to extra dimensions and exploring their astrophysical relevance.

Contribution

It introduces a new class of wormhole solutions with finite scalar fields and zero Ricci scalar in scalar-tensor gravity, satisfying the weak energy condition.

Findings

Wormholes are traversable under weak energy condition.

Scalar-tensor gravity can produce wormholes linked to extra dimensions.

Potential observational relevance in astrophysics.

Abstract

We obtain a large class of Lorentzian wormhole spacetimes in scalar-tensor gravity, for which the matter stress energy does satisfy the weak energy condition. Our constructions have zero Ricci scalar and an everywhere finite, non-zero scalar field profile. Interpreting the scalar-tensor gravity as an effective on-brane theory resulting from a two-brane Randall--Sundrum model of warped extra dimensions, it is possible to link wormhole existence with that of extra dimensions. We study the geometry, matter content, gravitational red-shift and circular orbits in such wormholes and argue that our examples are perhaps among those which may have some observational relevance in astrophysics in future. We also study traversability and find that our wormholes are indeed traversable for values of the metric parameters satisfying the weak energy condition.