This brings about horrible divide by zero problems and some very technical ways around that. The result is that we cannot unify quantum mechanics and general relativity. The string theory postulates that the fundamental entities are one-dimensional strings, the different vibrations of which give rise to different particles seen on our scale. The action takes place in a ten dimensional space of which six are curled up in such a way as to be unnoticed by us. Some experiments have been suggested recently which might be able to indirectly confirm the existence of dimensions other than the Big Four with which we are familiar.
Nothing can happen for there can be no place and no time.