I just read a book by Davies and Brown entitled "Superstrings: A Theory of Everything?" They dismiss 11D theory as having a fatal flaw: "A distinctive element of the weak interaction is that it breaks left-right mirror symmetry. This implies that elementary particles must be endowed with a definite handedness, or 'chirality'...It turns out that definite chirality only exists in spaces with an odd number of dimensions. This means that space must have an odd number of dimensions, and hence spacetime must have an even number of dimensions, otherwise there would be no chirality in the laws of nature. In short, eleven spacetime dimensions won't work." Any thoughts?