Ray Kurzweil's The Age of Spiritual Machines is an intriguing and engaging mixture of science and entertainment, along with a healthy dose of futurism. The idea of machine and human spirituality plays a role later in the book, but this is essentially a work about evolution in all senses of the word. It encompasses a description of biological evolution from the Big Bang to the present, the benefits and methods of evolutionary algorithms in computing and a forecast for the evolution of the human race through merging our bodies and minds with machines.

     Kurzweil opens by a discussion of the Law of Accelerating Returns, which asserts that: "As order exponentially increases, time exponentially speeds up." Put simply, this means that the more well organized the universe is, the more quickly significant events (such as formation of new structures in the universe, or most relevant in this case, jumps in evolution) can occur. This law models an exponential increase in the speed of evolution as it builds on its own order. The author relates this phenomenon to "Moore's Law," the oft-discussed principle of exponential technological growth equivalent to the doubling of computational power every two years.

     Before actually addressing the future, The Age of Spiritual Machines looks to the past, as it recounts key moments in a brief history of computing. Kurzweil particularly highlights the Turing test, a natural language oriented trial that many still consider the gold standard of tests for artificial intelligence. His discussion of how real intelligence can be recognized neatly transitions into one of the book's key issues: neural nets. These systems, patterned after the human brain, make use of massively parallel processing, and quite possibly also quantum computing, both of which are discussed in enough detail to satisfy a computer enthusiast and simply enough not to excessively bewilder a non-scientist.

     In the same engaging style, the decidedly knotty moral issue of scanning human brains in order to recreate and copy knowledge and memories apart from a physical human body is introduced. This topic is one that seems very likely to set off warning lights in many readers' minds. Sadly, the complex social issues this brings to the surface are largely discounted in light of the benefits to humanity the author foresees stemming from this and related technology, such as memory and sensory enhancement implants.

     As important as the brain is, Kurzweil also addresses the valid point that the essential human experience, it can even be said the human intelligence, revolves around that fact that we have bodies as well as minds. He believes that "the body and brain will evolve together, will become enhanced together, will migrate together towards new modalities and materials." This is supported by a discussion of the current practice of replacing joints, organs and the like, and the future possibilities of an increased lifespan facilitated by disease controlling microscopic "nanobots" and prosthetic limbs controlled directly by the neural system.

     After addressing the vaguely frightening idea that similar tiny intelligent robotics not only could be, but would necessarily be self replicating and what seems to be a favorite subject of his - virtual reality. He describes several possibilities for future implementations of the virtual world, from eyeglasses that project an image directly on the retinas, to a fully sensory engaging virtual reality booth and a "utility fog" of the above mentioned nanobots that can form and reform virtual bodies and environments.

     It is only at this point that the issue of machine spirituality is mentioned explicitly. Kurzweil takes the position that most of human religion is due to the possession of a "God spot", a small bundle of nerve cells near the front of the brain. He is of the opinion that a sensibility for religion is an integral part of consciousness, that machines "will claim to be conscious, and thus to be spiritual," and that ultimately humans will believe them.

     The remainder of The Age of Spiritual Machines is in essence a history of the next hundred years written in advance, by a man that is able to include a detailed list of past (very accurate) predictions. Even in light of Kurzweil's impressive record, many of the things he forecasts seem at first glimpse to very like science-fiction. His predictions for 2009, written ten years in advance, are a nearly even mix of technologies that are well on their way to becoming reality, things that need another few years thought and ideas that seem likely to remain just that for a long time to come. As he pushes further into the future the predictions get more unsettling, the point where, in the projected year 2099, human bodies as we know them have all but ceased to exist.

     These changes are watched and expressed through "Molly" an often entertaining personality who is addressed at the end of each chapter in a (sometimes rather contrived) 'interview' between the author and his reader. Molly's questions serve to clarify and highlight key topics, and introduce an amusing sub-plot - a rare thing in a non-fiction work.

     Kurzweil's style is unusual and his subject matter eclectic, as it seems fitting considering his widely varied career. He graduated MIT with a Bachelor of Science in Computer Science and Literature, and is known for his work with AI. Besides his many honorary degrees, Kurzweil his been honored with multiple prizes in the sciences and is the creator of the first print-to-speech readers for the blind and the original flat bed scanner.

     The worldview presented in this book is clearly not Christian, even apart from its heavy emphasis on themes of evolution. He identifies continued human advancement through evolution of technology as the greatest good of our existence, making almost no mention of any higher power and few actual forays into the spiritual; at least in the sense most Christians use the word.

     As a whole, his predications are both exciting and disturbing. I personally am astonished by the advances scheduled to occur within my probable lifetime, even without the 40 year extension of average life span Kurzweil calls for by 2029. Although billion-brain powered computers and self-driving cars may be less than threatening, I face the thought of "virtual sexual partners" and multiple virtual bodies per person with more than a little concern.

     Although this is not a book for everyone, I do consider it a valuable work for not only students in CS403, but all students and enthusiasts of technology. This book raises more moral and social impact issues than it puts to rest, and Kurzweil's literary style lends itself to opening discussions. The decidedly non-Christian outlook of this work could be both a challenge and an advantage to the student who really wants to probe the issues of what the future may hold and how technology will change our spirituality.