"Kaku's latest book aims to explain exactly why some visions of the future may eventually be realized while others are likely to remain beyond the bounds of possibility. . . . Science fiction often explores such questions; science falls silent at this point. Kaku's work helps to fill a void." --The Economist

"A fascinating exploration of the interface between science and science fiction, extremely well researched, lively, and tremendously entertaining." --Fritjof Capra, author of The Tao of Physics and The Science of Leonardo

"Mighty few theoretical physicists would bother expounding some of these possible impossibilities, and Kaku is to be congratulated for doing so. . . . [He gets] the juices of future physicists flowing." --Los Angeles Times