Dr. Can Kilic, Harvard
Astrophysical Constraints on Spontaneous Lorentz Violation
February 17, 2006

The discovery of dark energy as the major component of the
universe has led many to consider the possibility that there may be
something we are missing about gravity at large distances. The recent theory
of ghost condensation has defied the lore that trying to modify GR at large
distances is doomed from the start. As is usual in the case of gauged
symmetries, spontaneous symmetry breaking offers a way to modify the low
energy physics while maintaining the symmetry in the UV. In this work we use
ghost condensation as the effective theory of spontaneous Lorentz violation
and attempt to put bounds on its couplings to matter using astrophysical
considerations.