Astrophysicists and cosmologists play their mind games on the biggest of all boards--the entire known universe. Now Rees, director of Cambridge's Institute of Astronomy, suggests that even that may be only part of a greater game. Rees, who has swapped ideas at Cambridge with Stephen Hawking (who wrote the foreword to this book) and Roger Penrose, has an apt appreciation for the historical development of his discipline. Most of what we know about the inner workings of stars and the early days of the universe has been formulated in very modern times--essentially since Einstein's General Relativity Theory of 1915. Rees was a graduate student when quasars where first discovered, and he deftly describes this and other important cosmological discoveries of the last four decades. But the major focus of this book is on the new model of cosmology that has been developed since the Big Bang theory became the standard explanation of how the universe began. Several of the key variables of physics as we know it seem quite arbitrary, including the average density of matter (which determines whether the universe will continue to expand or ultimately collapse) and the ratio of ordinary matter to photons. At the age of one second, the universe seems to have settled upon the specific values of these quantities, though no one can say why. Matter took precedence over antimatter as the central component of the material part of creation. Rees suggests that other universes may well have evolved with different ratios and values, and speculates interestingly on the nature of space, time, and other physical constants in such alternate universes. At the same time, he fills in the history of modern cosmology in vivid detail, with clear explanations of some of the more erudite questions addressed in the last few decades. A strong and entertaining introduction to modern cosmology, by someone who has been close to the center of the debate.