From Library Journal
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.
H. James Birx, Canisius Coll., Buffalo, NY
Copyright 2002 Reed Business Information, Inc. --This text refers to the Hardcover edition.
From Scientific American
On the way to lunch at Los Alamos Scientific Laboratory one day in 1950, Enrico Fermi and three other physicists--Emil Konopinski, Edward Teller and Herbert York--chatted about flying saucers. At lunch, when the talk had turned to other matters, Fermi suddenly said, "Where is everybody?" His companions realized that the talk of flying saucers had turned his mind to the possibility that there is intelligent life elsewhere in the universe and that he was asking why, if there is, we have seen no sign of it. The question encapsulates what is now known as the Fermi paradox. Webb, lecturer in physics at the Open University in England, presents 49 solutions that have been proposed for the paradox, grouping them according to whether they hold that intelligent extraterrestrials are here, exist but have not communicated, or do not exist. He makes a splendid and enlightening story of it, concluding with his own solution, the 50th: "We are alone." 
 
http://www.amazon.com/Universe-Teeming-Aliens-WHERE-EVERYBODY/dp/1441930299/ref=sr_1_1?s=books&ie=UTF8&qid=1308514296&sr=1-1