The Spontaneous Compactification of the Closed Bosonic String
  We argue that the higher space-time derivative terms that occur in closed bosonic string field theory are reminiscent of those found in the Landau theory of liquid-crystal transitions. We examine the lowest level approximation of the closed bosonic string and find evidence for the existence of a new vacuum that spontaneously breaks Lorentz and translation symmetries. This effect can be interpreted as a spontaneous compactification of the theory. 
P. West