This book is recommended for any reader who is interested in the application of string theory to cosmology.<br><br>The first few chapters cover special relativity, general relativity, and quantum mechanics. The author must be commended for his vivid account of the scientific exploration in these important areas over the past century. His remarkably clear explanation, in terms that a lay reader should be able to follow without difficulty, makes it fun to read.<br><br>Nevertheless, reading becomes rather more difficult as the author goes into string theory and its applications in cosmology. Even as an accomplished string theorist, it must be very difficult for the author to explain in lay terms a relatively new theory in physics that involves complex mathematics (in topology and other areas). And to try to explain the intricacies of the theory without actually going into the mathematics involved makes the task doubly difficult. A lay reader's difficulty with the detailed account may also reflect the state of play of string theory, which has yet to receive the thorough study given to relativity and quantum mechanics over the course of the past century.