The nature of the universe has always fascinated me, and in this book I have found an excellent description of the one we live in.<br>Green begins by discussing the particles and forces that are the underpinnings of our universe. He then goes on to discuss the nature of light and what he calls "microscopic weirdness." It becomes evident as the information is presented that the general theory of relativity cannot explain everything. Quantum mechanics is necessary and this is where string theory enters the picture.<br><br>About the last two-thirds of the book discuss this theory. Here we learn about superstring theory, multiple dimensions, quantum geometry, how the fabric of space can tear and finally M-theory.<br><br>Green has saved the really esoteric scientific stuff for the notes section, and he has also provided a glossary section which was helpful. Nevertheless, I would not characterize this as an easy book to understand for the lay reader. I found that I had to stop reading after so many pages and simply digest what I had read. If you are involved in this field in any way, you probably will find it much easier. For me, this was my first exposure to this subject matter. Eventually I managed to get through all 400 plus pages of the book, and I enjoyed it immensely learning a great deal about the subject.<br><br>To help me remember all I was learning, I created an outline summary of the material in MS Word. I ended up with twenty-one pages of material. This gives you an idea of the wealth of information presented.<br><br>I highly recommend this book to anyone who has an interest in this subject matter.