The flexibility of optical metrics

TL;DR

This paper explores the concept of optical metrics, highlighting their flexibility and limitations in describing light propagation in nonlinear media and theories, with implications for materials and astrophysics.

Contribution

It demonstrates the versatility of optical metrics in nonlinear contexts and discusses their potential applications across physics and astrophysics.

Findings

Optical metrics can be flat and impermeable to photons in certain nonlinear theories.

They exhibit nontrivial behavior in nonlinear material media.

Potential applications extend to astrophysical systems and material sciences.

Abstract

We firstly revisit the importance, naturalness and limitations of the so-called optical metrics for describing the propagation of light rays in the limit of geometric optics. We then exemplify their flexibility and nontriviality in some nonlinear material media and in the context of nonlinear theories of the electromagnetism, both underlain by curved backgrounds, where optical metrics could be flat and impermeable membranes only to photons could be conceived, respectively. Finally, we underline and discuss the relevance and potential applications of our analyses in a broad sense, ranging from material media to compact astrophysical systems.