The more I learn about it, the more skeptical of String Theory I become. If it made predictions that could actually be tested I'd take it more seriously. Otherwise, it really falls under the weight of Occam's razor. It is far too complicated an explanation. Quantum Electrodynamics is bad enough on its own, but it at least makes predictions that have been tested over and over again. Maybe it is naive of me, but my gut feeling is that the rules that govern the universe are actually quite simple. It is just the implications of those rules that are complicated. Take any simple set of rules, or even a single rule, and increase the population the rule acts on to a paltry billion and see how complicated that gets. As N -> infinity things get pretty mind boggling.
Anyway, one thing that does puzzle me for any of the astrophysicists out there: If there is so much dark matter out there, what keeps it from gathering up like stars? Why is it so diffuse? Further, if it did gather up like stars, what would stop it from collapsing into singularities? I mean, the only reason stars don't collapse is because of the outward pressure of radiation from fusion (ok, and degenerate electron pressure in the case of white dwarves etc.) Seriously. Any clues?
You know, if there is that much dark matter out there, it stands to reason that stars are probably forming where dark matter draws the necessary gas clouds. i.e., stars would be forming in the middle of clumps of dark matter. The point: what if most of the mass of stars isn't baryonic matter at all?
Gah. Sounds pretty fishy but I'm too tired to find the error(s) in my reasoning.