- #1

- 6,724

- 431

Mentz114 posted this interesting link: http://arxiv.org/abs/gr-qc/0011087

Teleparallel Gravity: An Overview

Authors: V. C. de Andrade, L. C. T. Guillen, J. G. Pereira

Abstract: The fundamentals of the teleparallel equivalent of general relativity are presented, and its main properties described. In particular, the field equations, the definition of an energy--momentum density for the gravitational field, the teleparallel version of the equivalence principle, and the dynamical role played by torsion as compared to the corresponding role played by curvature in general relativity, are discussed in some details.

This confuses me, because it makes it clear that empirically observable phenomena can be attributed to either curvature or torsion, and yet there are also people, e.g., at UW, doing experimental searches for torsion, which is usually assumed to have spin as its source:

http://www.npl.washington.edu/eotwash/publications/pdf/lowfrontier2.pdf

This type of thing is discussed here:

http://math.ucr.edu/home/baez/gr/torsion.html

MTW has a discussion on p. 250 where they say that torsion would violate the e.p. E.g., if the UW Eot-Wash group got a non-null result from their spin-polarized torsion pendulum, it would clearly be a violation of the e.p., since it would be a composition-dependent motion in a gravitational field.

So are there some types of torsion that are empirically testable, violate the e.p., and are inconsistent with GR, while other types of torsion are just a different way of describing the same physics of GR?

Teleparallel Gravity: An Overview

Authors: V. C. de Andrade, L. C. T. Guillen, J. G. Pereira

Abstract: The fundamentals of the teleparallel equivalent of general relativity are presented, and its main properties described. In particular, the field equations, the definition of an energy--momentum density for the gravitational field, the teleparallel version of the equivalence principle, and the dynamical role played by torsion as compared to the corresponding role played by curvature in general relativity, are discussed in some details.

This confuses me, because it makes it clear that empirically observable phenomena can be attributed to either curvature or torsion, and yet there are also people, e.g., at UW, doing experimental searches for torsion, which is usually assumed to have spin as its source:

http://www.npl.washington.edu/eotwash/publications/pdf/lowfrontier2.pdf

This type of thing is discussed here:

http://math.ucr.edu/home/baez/gr/torsion.html

MTW has a discussion on p. 250 where they say that torsion would violate the e.p. E.g., if the UW Eot-Wash group got a non-null result from their spin-polarized torsion pendulum, it would clearly be a violation of the e.p., since it would be a composition-dependent motion in a gravitational field.

So are there some types of torsion that are empirically testable, violate the e.p., and are inconsistent with GR, while other types of torsion are just a different way of describing the same physics of GR?

Last edited by a moderator: