Could someone explain (briefly!) what M theory is, and voice their opinion on whether it sounds feasible? Is it a likely candidate for a Theory of Everything? From what I remember, string theory is a subset of M theory that arises naturally from M theory's precepts? Does M theory incorporate gravity? How many dimensions does it postulate? I'm sure there are web sites (and books) out there but I'm a busy guy and I want the condensed form! And I want to hear some discussion from you guys! P.S. I realize there is already a thread called "Superstring Theory.....How close?" but I want to inquire about M theory specifically.