Chapter Twelve, Beyond Strings, In Search of M-Theory Summary and Analysis

The discovery of five different versions of string theory is an embarrassment for physicists: they want one unified theory. String theory is still new, so the five theories may be a result of how physicists are analyzing the data, or they may actually be branches of a larger, overarching theory: M-theory. M-theory requires 11 different dimensions, ten space and one time. It contains not only vibrating strings, but other shapes as well: two dimensional membranes and three dimensional "blobs," among others. M-theory is even newer than string theory and so-called because it is a mystery.

The methods of research are limited because physicists have to use perturbation theory, or approximate answers. Strings interact by joining and splitting, and must "borrow" energy to momentarily burst into existence as two...