In 1995 the National Academy of Engineering (NAE) initiated the Frontiers of Engineering Symposium program, which every year brings together 100 of the nation's future engineering leaders to learn about cutting-edge research and technical work in different engineering fields. On September 14-16, 2000, the National Academy of Engineering held its sixth Frontiers of Engineering Symposium at the Academies' Beckman Center in Irvine, California. Symposium speakers were asked to prepare extended summaries of their presentations, and it is those papers that are contained here. The intent of this book, and of the five that precede it in the series, is to describe the content and underpinning philosophy of this unique meeting and to highlight some of the exciting developments in engineering today.