Of course, in standard analogue models such an aether field does not come with its own dynamics: It is a background structure which breaks the physically-relevant content of what is usually called diffeomorphism invariance (see next Section 7.4). However, in a gravitation theory context one might still want to require background independence taking it as a fundamental property of any gravity theory, even a Lorentz breaking one. In this case one has to provide the aether field with a suitable dynamics; we can then rephrase much of the analogue gravity discussion in the presence of nontrivial dispersion relations in terms of a variant of the Einstein-aether models [323, 180, 219, 314].
http://www.livingreviews.org/lrr-2011-3 |
Living Rev. Relativity 14, (2011), 3
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