@article{ijp2013111,
author={Belayev, Wladimir},
title={Comparison of Geodesics and Energy Variation Principles of Light Propagation},
journal={International Journal of Physics},
volume={1},
number={1},
pages={1--4},
year={2013},
url={http://pubs.sciepub.com/ijp/1/1/1},
abstract={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 G?del 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.},
doi={10.12691/ijp-1-1-1}
publisher={Science and Education Publishing}
}