Brian Greene is our generation's Carl Sagan: a scientific genius who happens to have a gift for analogy and explanation. His two previous books managed to be elegant, lucid, and funny about relativity, quantum mechanics, and string theory. The Hidden Reality examines several possible versions of the idea that our universe is only one among (or within) many. It's only a little more confusing than an episode of "Fringe" and even more entertaining. Buy it before the inevitable PBS miniseries. (Knopf)