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SUMMARY:Electromagnetic mediums with a double light cone structure - Dahl\
 , M
DTSTART:20110913T130000Z
DTEND:20110913T140000Z
UID:TALK32921@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:If we are given an electromagnetic medium we can compute the s
 peed of a propagating signal. For example\, in homogeneous medium we can c
 ompute the phase velocity of a planewave. A more challenging problem is to
  understand the converse problem: If we know the behaviour of signal speed
  in all possible directions\, what can we say about the medium?\n\nThe pro
 blem has a natural formulation on a 4-manifold representing spacetime. The
 n the Fresnel surface describes propagation speed in an electromagnetic me
 dium. For example\, in an isotropic medium the Fresnel surface is a Lorent
 z light cone. Conversely\, A. Favaro and L. Bergamin have proven that isot
 ropic medium is the only medium with this property (within a suitable clas
 s of linear mediums).  The purpose of this talk is to describe the analogo
 us problem when the Fresnel surface is the union of two Lorentz light cone
 s. Uniaxial crystals like calcite is one example. In addition\, we find tw
 o other medium classes with the same property.\n
LOCATION:Seminar Room 2\, Newton Institute Gatehouse
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