Brian Greene, here presents a 'Discovery Channel' type introduction, or more accurately, a glimpse, to String/M-theory, which is an attempt to unify General Relativity and Quantum Mechanics. The resonances of sub-Planck sized strings vibrating and interacting within (and around!) multi-dimensional Calabi-Yau space, are to account for the sub-atomic point particle masses, charges, and spins, as well as the force particles, of QM, with gravatation seamlessly incorporated. The presentation is clear, suspiciously so,.. with many analogies and quantification examples. Greene is a great science writer for the general public. In preparation for the main topic of the book, he provides a nice overview of General Relativity and Quantum Mechanics.<br><br>String theory is not yet a science, in the sense of being used in the field for making predictions;  it is incomplete, as Greene reminds the reader many times. String theory may end up being the greatest dead end in science, or the greatest triumph, though, with its 11 dimensions, some ultra small and 'curled up', whatever that means,... seems far from elegant as a description of reality. The problem will be how to verify this unification of gravity and QM experimentally.