Where is Everybody?

This book presents a set of 50 possible solutions to the Fermi Paradox ("where is everybody," i.e. if the universe is so big why haven't we met any other technological civilizations?). The solutions come in three main categories: they're already here, they exist but haven't communicated, and they don't exist. The book is not at all rigorous but serves as a broad-ranging introduction that includes more speculative material than the textbook below. My only quibble with this book concerns his chapters on evolutionary biology, where I don't feel he's fully acquainted with the complexity of the issue, but in fairness there isn't space to even begin to address those questions here. Overall this was a entertaining and good broad overview to a wide selection of factors to consider on the subject, from the physics of interstellar travel to von-Neumann probes and Dyson spheres, although a lot of the science is glossed over and I found a couple of his mathematical models a bit suspicious (or at least poorly defended).