Ekpyrotic Non-Gaussianity -- A Review
  Ekpyrotic models and their cyclic extensions solve the standard cosmological
flatness, horizon and homogeneity puzzles by postulating a slowly contracting
phase of the universe prior to the big bang. This ekpyrotic phase also manages
to produce a nearly scale-invariant spectrum of scalar density fluctuations,
but, crucially, with significant non-gaussian corrections. In fact, some
versions of ekpyrosis are on the borderline of being ruled out by observations,
while, interestingly, the best-motivated models predict levels of
non-gaussianity that will be measurable by near-future experiments. Here, we
review these predictions in detail, and comment on their implications.
