Enrico Fermi posed this question long ago - Where is everybody? He was referring to extraterrestrials - if incredibly advanced extraterrestrial civilizations exist, like many of us believe, where are they? Why haven't they visited us? Why haven't we at least heard from them or seen any signs of their existence?

This question has become known as the Fermi paradox. Over the years, many people (scientists and science fiction writers alike) have proposed many possible solutions. In this book, Webb examines fifty of these possible solutions. The solutions are divided into three categories: They exist and they're already among us, they exist but have not yet communicated, or they do not exist.

This book was fun to read because it is fun to speculate about the existence of aliens. Unfortunately, though, the author does not believe extraterrestrials exist, and it seems that his criticisms of the proposed solutions are almost all biased that way. It seemed like the author not only wished to examine each proposed solution, but also to disprove it. This bias was very annoying, of course, because deep down I very much want to believe that intelligent life exists elsewhere in the universe.

Despite all that, this was an interesting book because, as I said, it is fun to speculate on such a topic. And because we (mankind) have so little knowledge in the area, I can still choose to ignore the author's "pessimism" and choose not to believe his skepticism.