Aether dynamics
Since Lorentz-violating aether fields have so many fun uses, it's important to verify that the theories are well-behaved. With Tim Dulaney, Moira Gresham, and Heywood Tam, we investigated perturbations in the aether. We found that the results of a naive stability analysis were sensitively dependent on what Lorentz frame you do are looking in -- in a boosted frame, a purportedly stable model begins to look unstable. One exception was what we called "sigma-model aether," so we looked at the empirical constraints on that model. Our stability results have subsequently been challenged by Donnelly and Jacobson, who argue that everything can be fixed if you choose boundary conditions carefully.
S.M. Carroll, T.R. Dulaney, M.I. Gresham, and H. Tam, 2008, "Instabilities in the Aether'', arXiv:0812.1049. [abstract; pdf; SPIRES]
S.M. Carroll, T.R. Dulaney, M.I. Gresham, and H. Tam, 2008, "Sigma-Model Aether'', arXiv:0812.1050. [abstract; pdf; SPIRES]