The strong energy condition and the S-brane singularity problem

Recently it has been argued that, because tachyonic matter satisfies theStrong Energy Condition [SEC], there is little hope of avoiding thesingularities which plague S-Brane spacetimes. Meanwhile, however, Townsend andWohlfarth have suggested an ingenious way of circumventing the SEC in suchsituations, and other suggestions for actually violating it in the S-Branecontext have recently been proposed. Of course, the natural context fordiscussions of [effective or actual] violations of the SEC is the theory ofasymptotically deSitter spacetimes, which tend to be less singular thanordinary FRW spacetimes. However, while violating or circumventing the SEC isnecessary if singularities are to be avoided, it is not at all clear that it issufficient. That is, we can ask: would an asymptotically deSitter S-branespacetime be non-singular? We show that this is difficult to achieve; thisresult is in the spirit of the recently proved "S-brane singularity theorem".Essentially our results suggest that circumventing or violating the SEC may notsuffice to solve the S-Brane singularity problem, though we do propose two waysof avoiding this conclusion.Comment: 13 pages, minor corrections and improvements, references adde