Asymmetrically Warped Spacetimes

TL;DR

This paper explores asymmetrically warped spacetimes where the speed of light varies across extra dimensions, leading to potential Lorentz invariance violations and faster gravitational wave propagation, with solutions characterized by black hole parameters.

Contribution

It provides the most general form of asymmetrically warped spacetimes and analyzes their properties, including black hole solutions and junction conditions.

Findings

Bulk gravitational effects can cause apparent Lorentz violations.

Gravitational waves may travel faster than light on the brane.

Solutions are characterized by black hole mass and charge parameters.

Abstract

We investigate spacetimes in which the speed of light along flat 4D sections varies over the extra dimensions due to different warp factors for the space and the time coordinates (``asymmetrically warped'' spacetimes). The main property of such spaces is that while the induced metric is flat, implying Lorentz invariant particle physics on a brane, bulk gravitational effects will cause apparent violations of Lorentz invariance and of causality from the brane observer's point of view. An important experimentally verifiable consequence of this is that gravitational waves may travel with a speed different from the speed of light on the brane, and possibly even faster. We find the most general spacetimes of this sort, which are given by certain types of black hole spacetimes characterized by the mass and the charge of the black hole. We show how to satisfy the junction conditions and analyze the properties of these space-times.