Electromagnetic energy momentum in dispersive media
- School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9SS, Scotland (United Kingdom)
The standard derivations of electromagnetic energy and momentum in media take Maxwell's equations as the starting point. It is well known that for dispersive media this approach does not directly yield exact expressions for the energy and momentum densities. Although Maxwell's equations fully describe electromagnetic fields, the general approach to conserved quantities in field theory is not based on the field equations, but rather on the action. Here an action principle for macroscopic electromagnetism in dispersive, lossless media is used to derive the exact conserved energy-momentum tensor. The time-averaged energy density reduces to Brillouin's simple formula when the fields are monochromatic. The time-averaged momentum density for monochromatic fields corresponds to the familiar Minkowski expression DxB, but for general fields in dispersive media the momentum density does not have the Minkowski value. The results are unaffected by the debate over momentum balance in light-matter interactions.
- OSTI ID:
- 21537064
- Journal Information:
- Physical Review. A, Vol. 83, Issue 1; Other Information: DOI: 10.1103/PhysRevA.83.013823; (c) 2011 American Institute of Physics; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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ENERGY DENSITY
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FIELD EQUATIONS
FIELD THEORIES
INTERACTIONS
MAXWELL EQUATIONS
MINKOWSKI SPACE
MONOCHROMATIC RADIATION
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DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC RADIATION
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MAGNETISM
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PARTIAL DIFFERENTIAL EQUATIONS
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