Rating: 
Summary: A good survey, but won't change many minds
Review: This book does a good job of presenting most reasonable ideas of how to resolve the Fermi paradox.
I would have liked to see guesses at error bars for some of the conflicting estimates that create the paradox.
I wanted a better analysis of whether civilizations should be detectable by their heat output. His claim that they would operate at low temperatures is not obvious, and it's hard to tell whether anyone has put much thought into this question.
Rating:
Summary: Boggles the Mind
Review: This book is full of many interesting solutions about the many thoughts of aliens. Makes you wonder and think about all the different solutions people have come up with and if any of them are really right. Makes me think of what aliens will think of us when they find out all these solutions we have come up with about them. this informational book just leads the mind to more and more questions of the unknown and keeps you searching for answers.
No matter what your beliefs at the beginning of reasing this book, your eyes will be opened to other solutions that you can not prove to be wrong or right. It is an amazing mind boggling question...where is everybody?
Rating: 
Summary: Great read
Review: This book was a pleasure to read. (I just wish I had come across it earlier.) I've never encountered a more thorough treatment of Fermi's Paradox. But it's not simply a laundry list of questions and answers. Webb uses Fermi's Paradox to discuss many of the most interesting scientific and philosophical issues related to the debate over extraterrestrial life. His prose is clear, his reasoning is solid, and he treats the various sides of an often rancorous debate with respect. A paradigm of good science writing.
Rating:
Summary: A fun book
Review: This is a terrific, fun book to read. The author discusses 50 solutions to the Fermi paradox (you know the one: "if advanced alien civilizations exist, then why don't we see them?"), and does so very wittily. I didn't agree with all the arguments given in the book, but it many ways that's the whole point: this is the kind of topic you can have great fun arguing about. It captured my imagination, and it made me think - which is what I look for in books.My only criticism of the book is the awkward referencing system it uses. Numbers in the main text point to a "Notes and Further Reading" chapter (these notes are themselves fun to read!), but then numbers in this chapter point to a "References" chapter. It got confusing for a while.
Rating:
Summary: Well-written, interesting and thought provoking!
Review: This is an interesting "ideas" book. I'm a long-time Analog reader, so the notion of the Fermi paradox isn't exactly new to me - but many of the subjects discussed here I was coming across for the first time. The book contains an excellent historical account of the paradox; the meat of the book, though, is a discussion of 50 proposed solutions to the paradox (actually, 49 solutions, plus the author's summary). The summary contains an arithmetic error, as an earlier reviewer pointed out, but the error is essentially a typo. It doesn't affect the conclusion - in my opinion, you can have many more of the author's "steps". (That's my own take on the paradox - there are hundreds of hurdles that life has to jump over to reach intelligence; lots of scumworlds out there, but not many with civilizations that can build radio telescopes.) There's a lot of overlap with the well-known "Rare EArth", though Mr Webb's book is probably better written and more fun to read. I recommend both books.
Rating:
Summary: Well-written, interesting and thought provoking!
Review: This is an interesting "ideas" book. I'm a long-time Analog reader, so the notion of the Fermi paradox isn't exactly new to me - but many of the subjects discussed here I was coming across for the first time. The book contains an excellent historical account of the paradox; the meat of the book, though, is a discussion of 50 proposed solutions to the paradox (actually, 49 solutions, plus the author's summary). The summary contains an arithmetic error, as an earlier reviewer pointed out, but the error is essentially a typo. It doesn't affect the conclusion - in my opinion, you can have many more of the author's "steps". (That's my own take on the paradox - there are hundreds of hurdles that life has to jump over to reach intelligence; lots of scumworlds out there, but not many with civilizations that can build radio telescopes.) There's a lot of overlap with the well-known "Rare EArth", though Mr Webb's book is probably better written and more fun to read. I recommend both books.
Rating:
Summary: Great book - I see no multiplication error here
Review: This is an interesting and thought provoking book. Whether you agree with Webb's conclusions or not, the journey along the way contains *much* food for thought. The previous poster who claims to have found a multiplication error is in error, or the error has been corrected. In step 5 on page 238, he multiplies 5x10^5 by 20%, correctly yielding 10^5.
Rating:
Summary: Examining their navels?
Review: This is the most up-to-date and thorough discussion of the Fermi Paradox that I have read. Stephen Webb examines all the popular solutions as well as some esoteric ones, giving us considerable background on each along with the benefit of his knowledge on a wide range of relevant subjects including microbiology, plate tectonics, evolution, intelligence, language, philosophy, as well as astronomy and cosmology. And then he gives his solution: we are alone. That was Fermi's solution of course, and it is a popular one; however I don't think that Webb comes anywhere near to making a convincing case; and at any rate he is somewhat equivocal about whether his answer applies to the entire universe or to just the galaxy. It is clear that his answer applies only to life as we know it, having a carbon based biochemistry and a cellular structure. My feeling is that intelligent life forms may evolve from some other chemical basis or even from some use of energy and matter we know nothing about. On pages 237 to 239 Webb presents his argument that we are the only extraterrestrial civilization (ETC) in the galaxy by a process of elimination, i.e., life must be on a planet within both a galactic habitable zone (GHZ) and a solar continuously habitable zone (CHZ) around the right kind of star; must avoid cosmic disasters like supernovae; must have the right kind of moon, Jupiter, and plate tectonics; must evolve beyond single cells; must develop tool use and language, etc. He ends up sifting out everything except us, and the only reason he doesn't sift us out is that he has set us aside since we actually exist! This is close to sophistry, perhaps, but it has been argued before. I might call it the Fallacy of Elimination by Unknown Probabilities about Matters that May or May Not Be Essential. Putting that aside, consider this: If we extrapolate from what we know (as opposed to any speculation) about the existence of life in just our own galaxy, we should expect on average--at the very least--one ETC per galaxy. Wow. Far from being alone, this suggests more than 100 billion other ETCs are out there, although we are not likely to ever communicate with them. One of the things this book demonstrates, as others have before (see especially, Peter D. Ward and Donald Brownlee's Rare Earth: Why Complex Life Is Uncommon in the Universe [2000], which Webb acknowledges as influential), is that when you're dealing with so little concrete information in such a vastness, it is impossible to be entirely convincing one way or the other. The conclusion in Rare Earth, with which Webb concurs, is that life is common in the universe, but intelligent life is rare. I agree substantially with this, but my "rare" is perhaps larger than their "rare." Some of the familiar but crucial questions considered here were addressed in the excellent Extraterrestrials: Where Are They? (1995) edited by Ben Zuckerman and Michael H. Hart. For example, How long do ETCs exist before they go extinct? Is space travel enormously difficult and expensive or is it just very difficult? Do ETCs have a psychology similar enough to ours to make them want to communicate? How would they communicate, using what sort of medium?--even: would we recognize a communication from an ETC if we received one? The answer to these questions and many others is, we don't know. But it's fun to speculate; and in speculating at least we can eliminate many conceptual and logical errors that might crop up. Furthermore such speculations expand the mind and allow the imagination a greater range. In direct contrast to Webb I think there's only the smallest chance that we are alone. Amazing how people can come to such divergent conclusions from the same evidence! For such answers as, They are so advanced that they have no interest in communicating with us, and They are so into their own self-constructed pleasure-enhancing virtual existence that they care not to look outward, etc., Webb has a ready response. For such answers to solve the Fermi paradox, he says, they have to apply to every single ETC. Surely, he posits, not all ETCs would have such a psychology. But, by taking all such solutions and playing an elimination game similar to the one Webb plays on pages 237-239, we can reverse his conclusion and eliminate all existing ETCs as non-communicative for one reason or another, arriving at the grand conclusion that we are not alone and that there are indeed a whole bunch of ETCs out there. I wish I had the space to address some other Stephen Webb arguments that I think are faulty, but perhaps just one more will be suggestive. On page 229, while arguing that only humans have symbolic language, he relates an experiment in which a dolphin learns to operate an apparatus to release food. The dolphin is timed. Then the scientists close that dolphin off and release a second dolphin into the pool with the apparatus. The first dolphin can send signals to the second dolphin. The scientists then time how long it takes for the second dolphin to learn to work the apparatus. They discover that it takes the second dolphin on average just as long as it did the first. Webb writes: "We can conclude from this that the first dolphin was unable to tell the second dolphin how the apparatus worked." Well, maybe. But replace the dolphins with humans, and the reward of food with hundred dollar bills, and perhaps we might conclude that humans are also unable to communicate how the apparatus worked! Bottom line: for SETI enthusiasts and anyone interested in the prospect of extraterrestrial life, this is a book, despite its flaws, not to be missed.
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