Brane-World Motion in Compact Dimensions

TL;DR

This paper explores how the topology of compact extra dimensions in a brane-world scenario can break Lorentz invariance, allowing observers to detect their motion relative to a preferred frame through gravitational effects.

Contribution

It identifies three experimental effects that can reveal the motion of our universe in compact extra dimensions, including modifications to gravitational phenomena and boundary condition sensitivities.

Findings

Small extra dimensions can be detected if the brane moves fast enough.

Motion affects the properties of Kaluza-Klein modes and the Newtonian potential.

Experimental effects include twin paradox peculiarities and boundary condition sensitivities.

Abstract

The topology of extra dimensions can break global Lorentz invariance,singling out a globally preferred frame even in flat spacetime. Through experiments that probe global topology, an observer can determine her state of motion with respect to the preferred frame. This scenario is realized if we live on a brane universe moving through a flat space with compact extra dimensions. We identify three experimental effects due to the motion of our universe that one could potentially detect using gravitational probes. One of these relates to the peculiar properties of the twin paradox in multiply-connected spacetimes. Another relies on the fact that the Kaluza-Klein modes of any bulk field are sensitive to boundary conditions. A third concerns the modification to the Newtonian potential on a moving brane. Remarkably, we find that even small extra dimensions are detectable by brane observers if the brane is moving sufficiently fast.