§Is the
singularity locally or globally isotropic? (issue similar for de Sitter, cf. Starobinski)
§Is it
extendable (geodesic completeness)?
§Causality?
§Bounces in
closed FRW models: are these stable? Can they be used to model pre-big-bang and
perturbations? (currently exploring this idea with Valerio Bozza in Salerno; cf. Brandenberger et al. vs. Kaloper et al. 2006).
§Does
isotropy survive in strong non-linear regime? A first attempt at Bianchi
IX seems to confirm it (in progress with
Coley and Woei Chet).