Braneworlds in Constant and Accelerated Motion and Their Causal Characteristics

TL;DR

This paper explores how signals in braneworld models with extra dimensions can appear superluminal to observers, yet causality remains intact due to anisotropic propagation, with implications for cosmology and observable signatures.

Contribution

It generalizes previous work by analyzing signals in moving and tilted branes, revealing conditions under which apparent superluminal signals do not violate causality.

Findings

Bulk signals can appear superluminal to brane observers.

Anisotropies in signal propagation preserve causality.

Potential observable signatures for braneworld cosmology.

Abstract

We generalize prior work on the signatures of bulk signals detected by brane-based observers in a spacetime with a compactified dimension. When such braneworlds move with constant velocities or constant proper accelerations in the extra dimension, the observers may witness apparent superluminal signaling. Our analysis includes tilted branes that are partially wrapped along the compact dimension. We identify parameters that help characterize various scenarios. Despite the apparent superluminality of bulk signals, we show that anisotropies in their propagation relative to the brane-based observer preserve causality. Some of the effects studied here could be the basis for alternative cosmological models, as well as observable signatures of braneworld scenarios.