This book is well written, clear, and concise. It is also challenging, amazing, and, at times, difficult to understand. Johnson begins with some brain freezing descriptions of what quantuum computing can do (trust me... its freaky), then delves into what a computer is and how quantum computing may be applied. A must read for those who want to stay on the cutting edge of science or computing, but dont have time for four more years of school.
George Johnsons articles in The New York Times about quantum computing would make British tabloids green with envy for his talent to sensationalize and to omit important information that runs contrary to his opinions. Mr. Johnsons quantum computing articles have even been satirized on the web, with titles like "IBM Builds Special Computer to Factor Number 15". So I was very surprised to see that this book is not very sensationalist at all. I thought it was on the whole farily balanced. It appears that George has been stung by his satirists and is trying to reform himself. For this I commend him. However, the transformation is not complete yet: he still mysteriously forgets to mention in the book that NMR computers do not produce entanglement. But at least we can all sigh from relief in that he mentions Seth Loyd only once.
* George Johnsons A SHORTCUT THROUGH TIME could be subtitled "A Beginners Guide To Quantum Computing and Cryptography", with this book exploring the bizarre quantum phenomena that could, in potential, be used to perform computations on a range of numbers simultaneously, or produce ciphers that are literally impossible to crack by analytical means. Trying to say more about the concepts discussed in this book in a short review is impossible -- explaining how a particle will simultaneously exist in all its possible states at once until its measured will give either a blank stare or a bland "yeah right I know", meaning it didnt really register -- but it isnt necessary, because Mr. Johnson does a right nice job of explaining such matters in this neat brief book. His writing is extremely clear and concise, at least relative to the difficult matters he is discussing, and the book is tidily illustrated. This is, to be sure, a book for beginners, and in fact it spends some time up-front explaining basics of computers before it moves on to quantum effects. A specialist will likely have NO use for it, and might even be a bit scornful at Mr. Johnsons occasional excursions into arm-waving. In fact, I did have some real problems with his discussions of Shors and Groves quantum-computing algorithms, when Mr. Johnson did seem to be getting into some real arm-waving. Well, given the difficulty of the material, he was likely to fall into that trap in places, and maybe I should just give him the benefit of doubt, read that material again a few times, and sleep on it. However, I was basically familiar with quantum computing and cryptography (at a layman level) before I read this book, and at the outset thought it might not tell me anything I didnt already know. I was wrong since I got a tidy explanation of the application of quantum teleportation to cryptography (blank stare out there?), and some other nice tidbits. Besides, I was thoroughly impressed by Mr. Johnsons sensibility in his comments about technical writing and his degree of cautious skepticism in dealing with physicists, some of whom seem to be slightly around the bend. The late Dick Feynman, who plays a part of sorts in this book, could actually understand what the such sorts were saying and nail them, but the rest of us will just have to sympathize with Mr. Johnson when he makes comments such as: "Gilles Brassard tells me that each dim flash, on the average, contains perhaps one-tenth of a photon, an idea I find rather difficult to grasp." You just gotta like this guy.
