Struggling to find time in a busy schedule for yet another interview, Ray Kurzweil jokes that the media frenzy surrounding him these days only happens "every thousand years." That's because the inventor and entrepreneur who brought us such products as the Kurzweil electronic keyboard, a text-to-speech reading machine for the blind and voice-recognition software is also one of the most audacious-and, some say, accurate-futurists around. Kurzweil's fearlessly detailed predictions make his latest book, The Age of Spiritual Machines, a must-read for the turn of the millennium.

TR Associate Editor Rebecca Zacks visited Kurzweil at the Wellesley Hills, Mass., offices of Kurzweil Technologies, one of the half-dozen high-tech companies he has founded since selling his first major enterprise to Xerox in 1980. The son of a composer and trained as an MIT undergraduate in both computer science and creative writing, Kurzweil moves deftly from music and art to computer processors and nanotechnology to immortality, evolution and God. And though his manner and his gray pinstriped suit are remarkably subdued, his ideas about the future are explosive.

TR: You're accomplished both as an inventor and as a writer-how do you see those two roles fitting together?
KURZWEIL: In writing, you're also inventing. My main interest is to write about the future, though I did write a health book. Lately, my interest in health has intersected with my interest in computers, because they both have a bearing on the issues of longevity and immortality-keeping our biological bodies and brains healthy is the first bridge to immortality. That'll bring us to the bioengineering revolution. Within 10 years, bioengineering will extend human life spans at least a year every year. And that'll be the second bridge that'll bring us to the nanotechnology artificial intelligence revolution, which gives us a real shot at immortality. But writing about the future and technology is also an invention process, because you have to invent the future to have a compelling statement about it.

TR: One of your more dramatic statements is that in the second half of the 21st century we'll routinely be able to scan a person's brain and "reinstantiate" that person in a computer-no more squishy human body necessary. What did you have to mentally invent to come up with that scenario?
KURZWEIL: People ask, "How is that possible, scanners really can't resolve to that resolution," so I came up with the idea of scanners that would scan the brain from inside. We already have scanners that can scan with extremely high resolution, providing the scanning tip is right next to the neural features. Well, how are you going to move the scanning tip to every point in the brain without destroying the brain? The answer is to send them in as nanobots, blood-cell-sized robots with little scanners that would travel through every capillary in the brain. How would they communicate with each other? They would all be on a wireless local area network, and they would use distributed processing, thus the computational ability of the nanobots would be assembled into one distributed parallel computer.

TR: Is this something we could do today?
KURZWEIL: Every aspect of it is feasible today, except for the size and the cost. And that's where what I call the "Law of Accelerating Returns" comes in: There are all these accelerating technological processes that are increasing exponentially the cost effectiveness of computing. So the requisite computing for this scenario will be quite feasible within 25 to 30 years. What about size? Well, miniaturization is another exponential trend in technology, and right now we're shrinking the size of technology by a factor of 5.6 per linear dimension per decade, so again, you can predict that this will be feasible within 30 years.