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A covariant description of a generic electromagnetic medium requires a set of 36 independent parameters, instead of two ordinary material parameters, ε and μ. Such a set is arranged in a 4-th order constitutive tensor. Due to the group theory, this tensor is irreducibly decomposed into the sum of three independent sub-tensors. The first principal part is a substitution of the classical set of parameters. Two other tensors, skewon and axion, have no classical analogs and may represent some novel properties of media or artificial materials. In my talk, I will describe how the generalized covariant dispersion relation is derived. The result is in a correspondence with the formula proposed by Hehl, Obukhov and Rubilar. I define the notion of optic tensor (an analog of acoustic tensor from elasticity) and describe its properties. With this new device, I show some new results about the skewon modified media. The most visual outcome is a proof that in the skewon modified vacuum the wave propagation is necessary superluminal. It means that the skewon is probably forbidden in vacuum, but not in material media.

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Yakov Itin, Hebrew University of Jerusalem and Jerusalem College of Technology
Seminarraum Theoretische Physik
Contact: not specified