Techno-heaven or techno-hell? If you believe many scientists working in the emerging fields of twenty-first-century technology, the future is blissfully bright. Initially, human bodies will be perfected through genetic manipulation and the fusion of human and machine; later, human beings will completely shed the shackles of pain, disease, and even death, as human minds are downloaded into death-free robots whereby they can live forever in a heavenly "posthuman" existence. In this techno-utopian future, humanity will be saved by the godlike power of technology.

If you believe the...