Brane surgery: energy conditions, traversable wormholes, and voids

TL;DR

This paper explores how negative tension branes in string theory can lead to exotic spacetime structures like traversable wormholes and voids, challenging traditional energy conditions and theorems.

Contribution

It introduces the concept of 'brane surgery' using the Israel--Lanczos--Sen formalism to analyze the dynamics of negative tension branes and their resulting spacetime geometries.

Findings

Negative tension branes violate standard energy conditions.

Traversable wormholes and voids can naturally arise from brane configurations.

These phenomena are generic in D-brane models with negative tension branes.

Abstract

Branes are ubiquitous elements of any low-energy limit of string theory. We point out that negative tension branes violate all the standard energy conditions of the higher-dimensional spacetime they are embedded in; this opens the door to very peculiar solutions of the higher-dimensional Einstein equations. Building upon the (3+1)-dimensional implementation of fundamental string theory, we illustrate the possibilities by considering a toy model consisting of a (2+1)-dimensional brane propagating through our observable (3+1)-dimensional universe. Developing a notion of "brane surgery", based on the Israel--Lanczos--Sen "thin shell" formalism of general relativity, we analyze the dynamics and find traversable wormholes, closed baby universes, voids (holes in the spacetime manifold), and an evasion (not a violation) of both the singularity theorems and the positive mass theorem. These features appear generic to any D-brane model that permits negative tension branes: This includes the Randall--Sundrum models and their variants.