As a lay theologian, I must respond to him by saying that the ideas of a closed-loop Universe is not in the least troubling. In fact, it harmonizes nicely with Scriptural statements about God being "The Alpha and Omega, the beginning and the end, the first and the last." God may be the "super scientist" he speculates about who created our reality in his lab. Believers may want to read "Beyond the Cosmos" by Hugh Ross as a companion volume to this book.
To his credit, however, Gott takes a neutral position on religious matters, unlike others in his profession, who seem to have embarked on a war against the "Old One," as Einstein called his Maker.
I believe that previous reviewers have been far too hard on Gott for tooting his own horn. I for one admire his enthusiasm for his theories. The last bit on using the copernican principle to make predictions was...well, I hope it was written tongue in cheek. Predicting that Christianity, for ex., would last no more than another 76,000 years is a pretty safe prophecy.
All in all, this book is an entertaining and informative read. It may have been an even better one had Gott tempered his enthusiasm with some good old fashioned intellectual caution.
Gott, a professor of astrophysics at Princeton University, discusses almost every aspect of time travel, including what time is and why it seems to be unidirectional. He also covers the origin of the universe and what might have happened "before" it came into being, including oscillating universes, de Sitter spacetime, bubble universes, self creating universes, and universes tunneling from nothing. Most intriguing was the possibility that universes might be created like test-tube babies in a lab by supercivilizations. According to the author, by compressing a mass into an extremely high density black hole, "occasionally it would branch off by quantum tunneling to create a baby universe hidden inside the black hole. This branch could grow up to a large size without interfering with the lab (the trunk universe) (p. 191)." The possibility of a multiverse is also examined, as are alternative realities.
Probably the most interesting part of the book for me was the final chapter, Report from the Future. Here the author uses the Copernican principle to predict various events. I have to admit, however, that by allowing himself a 95% range he makes his predictions pretty close to inescapable in some instances. For instance, he predicts the future longevity of the internet based upon a start date of 1969 as being more than 9 months (this prediction was made in 2001, so it has already exceeded the low end prediction) but less than 1,209 years! Those are pretty safe odds!
Still, his extension of that principle to an analysis of our future as a species and of the character of life elsewhere is an interesting one. He points out that as he-or you or I-are not "special" in the scheme of things (any more than the earth is the center of the solar system, the sun the center of the galaxy or the galaxy the center of the universe), our time and its character are not likely to be special either. In short, whatever is examined should have a great likelihood of being the norm or average condition for that trait. The assumptions that he draws from this premise are truly impressive. For instance, since we are intelligent observers, if we apply the Copernican principle and assume that we are not special much can be said. He writes, "You should expect to live in an epoch of the universe in which the population of intelligent observers is high because most intelligent observers would live in such an epoch (p. 237)." He notes that the answer to Fermi's famous question about extraterrestrials, "Where are they?" would be that they "must still be sitting on their home planet, just like you; otherwise you would be special. Simple (p. 237)." With respect to the time in which the reader lives, he writes, "A graph of the population history of our species might...show low levels during its initial hunter-gather phase, then a brief spike to 12 billion because of civilization, followed by a crash back to hunter-gatherer levels. You expect to live in the spike because most people will (p. 224)." In short, you have little likelihood of living at either the beginning or the end of human culture, because most of the people who have ever lived are living now.
Though it's not an easy book to understand, it's still a very engaging work.