OK the very origin of string theory is based on the observations of the regge trajectories pert. to hadrons. Funnily enough you get the relation that the ang. mom. is directly proporitional to the square of the energy (if i remember correctly) which would not be the case if we were dealing with, say, a rod. Well if you ignore the potential of the wave eq. for a moment (we set it to 0), we somewhat appr. get p^2~E where p is momentum and E is energy and ~ is the symbol for proportionality. That seems to be the reversed relation. Of course, this is the relation in classical physics, but classical physics is a apprx. of the more "correct" QM so let's stick to QM. And i'm igoring theory of rel. for the moment. Well, the above is a bit fuzzy, but if anyone knows why you have these opposite relations. I know there are lot of assymmetries here, like the first case concerns angular momentum, while the second case is not restricted in that manner.