Preface This book was born out of my fascination and involvement with science in the area of overlap between biology and computer science—two disciplines that on the surface may seem to have little commonality. My introduction to this field came several years ago, while working on a defense-related government research project whose objective was to explore unconventional ways of computing without the use of silicon. The scientists and engineers associated with this project constituted about as renowned and creative a cadre of multidisciplinary minds as could be found anywhere in the world, and they had been given relative freedom to explore and implement some truly original, even radical ideas for non-silicon-based information processing systems. As a consequence, I learned about such revolutionary forms of infor- mation processing as quantum computing (based on the manipulation of atomic particles, such as electrons or nuclei, for carrying out the binary logic of computation), computing with strands of DNA, or how to con- struct digital logic gates inside living cells. As part of the thought process of reinventing computing, some researchers saw the need to return to the conceptual foundations of the discipline, reexamining computing’s early models or such basic notions as the thermodynamical relationship between energy and information processing. Others explored how best to exploit the various advantages that information processing in differ- ent media would present over conventional silicon computers, such as an increase in parallel processing ability (DNA computing) or in speed (quantum computation); or whether there were aspects of biological systems, such as a swarm of bees or the mammalian brain, that could be co-opted as a basis for new models for algorithm development, or more efficient hardware.