Imagine a world where whole epochs will pass, cultures rise and fall, between a telephone call and the reply. Think of the human race multiplying 500-million fold, or evolving new, distinct species. Consider the technology of space colonization, computer-assisted reproduction, the "Martian potato." One hundred years after H. G. Wells visited the future in The Time Machine, Freeman Dyson marshals his uncommon gifts as a scientist and storyteller to take us once more to that ever-closer, ever-receding time to come.

Since Disturbing the Universe, the book that first brought him international renown, Freeman Dyson has been helping us see ourselves and our world from a scientist's point of view. In Imagined Worlds he brings this perspective to a speculative future to show us where science and technology, real and imagined, may be taking us. The stories he tells--about "Napoleonic" versus "Tolstoyan" styles of doing science; the coming era of radioneurology and radiotelepathy; the works of writers from Aldous Huxley to Michael Crichton to William Blake; Samuel Gompers and the American labor movement--come from science, science fiction, and history. Sharing in the joy and gloom of these sources, Dyson seeks out the lessons we must learn from all three if we are to understand our future and guide it in hopeful directions.

Whether looking at the Gaia theory or the future of nuclear weapons, science fiction or the dangers of "science worship," sea-going kayaks or the Pluto Express, Dyson is concerned with ethics, with how we might mitigate the evil consequences of technology and enhance the good. At the heart of it all is the belief once expressed by the biologist J. B. S. Haldane, that progress in science will bring enormous confusion and misery to humankind unless it is accompanied by progress in ethics.

Freeman Dyson is Professor Emeritus in the School of Natural Sciences, Institute for Advanced Study, Princeton.