In response to Enrico Fermi's famous 1950 question concerning the existence of advanced civilizations elsewhere, physicist Webb critically examines 50 resolutions to explain the total absence of empirical evidence for probes, starships, and communications from extraterrestrials. He focuses on our Milky Way Galaxy, which to date has yielded no objects or signals that indicate the existence of alien beings with intelligence and technology. His comprehensive analysis covers topics ranging from the Drake equation and Dyson spheres to the panspermia hypothesis and anthropic arguments. Of special interest are the discussions on the DNA molecule, the origin of life on Earth, and the threats to organic evolution on this planet (including mass extinctions). Webb himself concludes that the "great silence" in nature probably results from humankind's being the only civilization now in this galaxy, if not in the entire universe. This richly informative and very engaging book is recommended for most academic and public library science collections.