M-theory is not yet complete; however it can be applied in many situations (usually by exploiting string theoretic dualities [clarification needed]). The theory of electromagnetism was also in such a state in the mid-19th century; there were separate theories for electricity and magnetism and, although they were known to be related, the exact relationship was not clear until James Clerk Maxwell published his equations, in his 1864 paper A Dynamical Theory of the Electromagnetic Field. Witten has suggested that a general formulation of M-theory will probably require the development of new mathematical language.

— Wikipedia on M-theory

2010.05.05 Wednesday ACHK