M-theory Quotes

The BEH mechanism operates within the context of gauge theories. Despite the fact that grand unification schemes reach scales comparable to the Planck scale, there was, a priori, no indication that Yang-Mills fields offer any insight into quantum gravity. The only approach to quantum gravity that had some success, in particular in the context of a quantum interpretation of the black hole entropies, are the superstring theory approaches and the possible merging of the five perturbative approaches (Type IIA, IIB, Type I and the two heterotic strings) into an elusive M-theory whose classical limit would be 11-dimensional supergravity. (Francois Englert)
Why is space-time doomed? There are many reasons, among which: In string theory we can change the dimension of space-time by changing the strength of the string force. Thus, the so-called II-A string theory, which semi-classically describes closed strings moving in ten-dimensional flat space for very weak coupling is dual for strong coupling to a theory, called M-theory, that at low energies is described by eleven-dimensional supergravity. By increasing the string coupling we can grow an extra dimension. How can the spatial continuum be fundamental if the number of spatial dimensions can be so changed? View quote
David Gross