International Journal of Physics
ISSN (Print): 2333-4568 ISSN (Online): 2333-4576 Website: Editor-in-chief: B.D. Indu
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International Journal of Physics. 2013, 1(1), 1-4
DOI: 10.12691/ijp-1-1-1
Open AccessReview Article

Comparison of Geodesics and Energy Variation Principles of Light Propagation

Wladimir Belayev1,

1Center for Relativity and Astrophysics, Saint-Petersburg, Russia

Pub. Date: March 04, 2013

Cite this paper:
Wladimir Belayev. Comparison of Geodesics and Energy Variation Principles of Light Propagation. International Journal of Physics. 2013; 1(1):1-4. doi: 10.12691/ijp-1-1-1


The propagation of light on a set of null paths in a pseudo-Riemannian manifold is studied using a variational principle of extremal energy. This method is compared with those based on the geodesics and Fermat principles. For the static space-time all three variational methods give the same solutions. The Fermat principle for stationary gravitational fields is identical to the principle of variation of energy of light-like particles. The approach proposed here is applied to a flat expanding space, corresponding to the LCDM-model, and generalized Gödel space-time. In the first case a solution obtained by the method of energy variation coincides with the geodesic method, while in the second case they give different solutions.

variational methods Lagrangian light-like particle Fermat principle geodesics

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