Raymond C. Kurzweil is the author of The Age of Intelligent Machines, published in 1990, and The Age of Spiritual Machines: When Computers Exceed Human Intelligence, published this year. He is the founder and chairman of Kurzweil Technologies in Wellesley Hills, Mass., as well as five other companies that still bear his name or are still operating under new ownership. He spoke with Business Week Senior Writer Otis Port about the separate and joint futures of human and artificial intelligence.

Q: Do you have any doubts that a superior intelligence will emerge in the next few decades?
A: No. It's inevitable. For example, nanotubes would allow computing at the molecular level. A one-inch cube of nanotube circuitry would be about 1 billion times more powerful than the human brain, in terms of computing capacity. That raw computing capacity is a necessary but not sufficient condition to achieve human-level intelligence in a machine.

We also need the organization and the software to organize those resources. There are a number of scenarios for achieving that. The most compelling is reverse-engineering the human brain. We're already well down that path, with techniques like MRI. But we'll do better because the speed and resolution -- the bandwidth -- with which we can scan the brain are also accelerating exponentially.

One means of scanning the brain would be to send small scanners in the form of nanobots into the blood stream. Millions of them would go through every capillary of the brain. We already have electronic means for scanning neurons and neurotransmitter concentrations that are nearby, and within 30 years we'll have these little nanobots that can communicate with each other wirelessly. They would create an enormous database with every neuron, every synoptic connection, every neurotransmitter concentration -- a precise map of the human brain.

So we'll have the templates for human intelligence, and by then we'll have the hardware that can run these processes. So we can reinstate that information in a neural computer.

Once we can embody human thought processes in a nonbiological medium, it will necessarily soar past human intelligence -- for several reasons. First, machines can share their knowledge electronically. With humans, you spend years teaching language to each child. [But] once any one machine has mastered something, it can share that knowledge instantly with millions of other machines over the global wireless Web, which we'll have by then. So a machine can become expert at any number of disciplines.

Secondly, machines are far faster. Electronic circuits are 10 million times faster than neural connections, and machine memories can be far larger and much more accurate. However, machines do not yet have the depth of pattern recognition or the subtlety of human intelligence. They can't deal with emotions and humor and other subtle qualities of human intelligence.

Once their complexity matches that of humans and they are able to master the skills at which humans now excel, and those abilities are combined with the ways in which machines are already superior -- that will be a very formidable combination. It'll get to the point where the next generation of technology can only be designed by the machines themselves.

Finally, while the complexity of the biological computational circuitry in humans is essentially fixed, the density of machine circuitry will continue to grow exponentially. By 2030, a $1,000 computer system will have the power of 1,000 human brains; by 2050, 1 billion human brains.

Q: Won't we end up feeling like pets?
A: Those same nanobots that can scan the human brain will also provide a type of neural implant to extend human intelligence -- expand your memory and improve your pattern-recognition capabilities. Ultimately they will augment human intelligence quite profoundly as we go through the 21st century.

We are doing this today, after a fashion. We now have neural implants for Parkinson's disease patients that actually reprogram their neural cells. The implants literally turn off the symptoms of Parkinson's as soon as you throw a switch. It's very dramatic. These patients are wheeled in, their bodies frozen. Then a switch is thrown to activate the neural implants, and the patients suddenly come alive -- their symptoms are suppressed by the implant.

With microscopic nanobots, we'll be able to send millions or billions [of them] into your brain. They would take up key positions inside our brains and detect what's going on in our brains. They would be communicating with each other, via a wireless local-area network, which would be linked to the wireless Web and intelligent machines, and they could cause particular neurons to fire, or suppress them.

This will enable us to artificially boost human intelligence dramatically. Ultimately, the majority of thinking will be done in the nonbiological parts of our brains.

Q: If nanobots are sitting inside our heads and controlling the brain, how will we know they're not fooling us with false signals?
A: Well, actually, another thing we could do with this would be virtual reality. If we had nanobots take up positions by every nerve fiber that comes from all of our five senses, they could either sit there and do nothing, in which case you'd perceive the world normally -- or they could shut off the nerve impulses coming from our real senses and replace them with simulated nerve impulses representing what you would perceive if you were in the virtual environment.

Q: So we wouldn't be able to tell the difference at all between the real world and a simulated world?
A: Right. It would be as if you were really in that virtual environment. If you decided to walk, the nanobots would intercept the signals to your real legs and send back all the sensory signals of walking -- from the changing tactile pressure on your feet to the air moving across your hands as you swing your arms. It would be just as high-resolution and just as compelling as real reality. You could actually go there and meet other real people. So you and I, instead of being on the telephone, could be meeting on a Mozambique game preserve, and we'd both feel the warm breeze on our faces and hear the animal sounds in the background.

Eventually, anything you can do in real reality -- business meetings, social events, sex, sports -- could be done in virtual reality. As the technology gets perfected, we'll be spending more and more time in virtual reality, because it'll be more and more compelling. Going to Web sites will mean going to a virtual reality environment. Some will emulate real environments, so you'll visit the Web to go skiing in the Alps or to take a walk on a beach in Tahiti. Others will be fantastic environments that don't exist, or couldn't exist, in the real world.

Q: Let's go back to machines that design new machines. Doesn't that open the potential for them to evolve a nonhuman intelligence -- utterly different ways of thinking?
A: Sure. Once we have intelligent systems in a nonbiological medium, they're going to have their own ideas, their own agendas. They'll evolve off in completely unpredictable directions. Instead of being derived only from human civilization, new concepts will also be derived from their electronic civilization. But I see this as part of evolution -- a continuation of the natural progression.

Q: But couldn't it pose a threat to the human race?
A: I don't see an invasion of alien machines coming over the horizon. They'll be emerging from within our human-machine civilization. We're already quite intimate with our technology. If all the computers stopped today, essentially everything would grind to halt. That was not true just 30 years ago. At that point only a few scientists and government bureaucrats would have been frustrated by the delay in getting printouts from their punch-card machines.

Today we've become highly dependent on computer intelligence. It's already embedded in our decision-making software much more than most people realize. That's going to continue to accelerate.

Next, we're going to be putting these machines into our bodies and into our brains. So it's not going to be humans on one side and machines on the other. There's not going to be a clear distinction between humans and machines. We'll be using nanobots to expand human intelligence, and over time, the bulk of our thinking will be done in the nonbiological parts of our brains, because that part of our brain will continue to grow as technology advances. But the biological part is not growing.

Q: There won't be a clear distinction between us and them?
A: No. Ultimately, you're going to have nonbiological entities that are exact copies of biological brains. They will claim to be human, because they will have all the memories of the original brain. So there won't be a clear distinction between what's human and what's not.

But remember, this will be emerging gradually from within our own civilization. It's the next phase of our own evolution. It's only a threat if you believe things should always stay the same as they are today.

That's not to say there aren't any dangers. An obvious one is uncontrolled growth of these nonbiological entities in your body -- nonbiological cancer.

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