General Relativity and Gravitation

, Volume 36, Issue 6, pp 1335–1360

Extra Force from an Extra Dimension: Comparison Between Brane Theory, Space-Time-Matter Theory, and Other Approaches

  • J. Ponce de Leon

DOI: 10.1023/B:GERG.0000022391.57597.3b

Cite this article as:
de Leon, J.P. General Relativity and Gravitation (2004) 36: 1335. doi:10.1023/B:GERG.0000022391.57597.3b


We investigate the question of how an observer in 4D perceives the five-dimensional geodesic motion. We consider the interpretation of null and non-null bulk geodesics in the context of brane theory, space-time-matter theory (STM) and other non-compact approaches. We develop a “frame-invariant” formalism that allows the computation of the rest mass and its variation as observed in 4D. We find the appropriate expression for the four-acceleration and thus obtain the extra force observed in 4D. Our formulae extend and generalize all previous results in the literature. An important result here is that the extra force in brane-world models with Z2-symmetry is continuous and well defined across the brane. This is because the momentum component along the extra dimension is discontinuous across the brane, which effectively compensates the discontinuity of the extrinsic curvature. We show that brane theory and STM produce identical interpretation of the bulk geodesic motion. This holds for null and non-null bulk geodesics. Thus, experiments with test particles are unable to distinguish whether our universe is described by the brane world scenario or by STM. However, they do discriminate between the brane/STM scenario and other non-compact approaches. Among them the canonical and embedding approaches, which we examine in detail here.

Kaluza-Klein theory general relativity 

Copyright information

© Plenum Publishing Corporation 2004

Authors and Affiliations

  • J. Ponce de Leon
    • 1
  1. 1.Laboratory of Theoretical Physics, Department of PhysicsUniversity of Puerto RicoSan JuanPuerto Rico

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