Fermat's principle and the variational analysis of an optical model for light propagation exhibiting a critical radius

摘要

Fermat's principle is used to analyze the trajectories of light propagating in a radially inhomogeneous medium with a singularity in the center. It is found that the light trajectories are similar to those around a black hole, in the sense that there exists a critical radius within which the light cannot escape, but spirals into the singularity. (C) 2002 American Association of Physics Teachers. [References: 9]