In a small medical office on the outskirts of Denver, with windows overlooking the dirty snow and the golden arches of a fast-food mini-mall, one of the world's leading longevity physicians, Terry Grossman, works on keeping Ray Kurzweil alive. Kurzweil is not Grossman's only client. The doctor charges $6,000 per appointment, and wealthy singularitarians from all over the world visit him to plan their leap into the future.

Grossman's patient today is Matt Philips, 32, who became independently wealthy when Yahoo bought the Internet advertising company where he worked for four years. A young medical technician is snipping locks of his hair, and another is extracting small vials of blood. Philips is in good shape at the moment, but he is aware that time marches on. "I'm dying slowly. I can't feel it, but I know its happening, little by little, cell by cell," he wrote on his intake questionnaire. Philips has read Kurzweil's books. He is a smart, skeptical person and accepts that the future is not entirely predictable, but he also knows the meaning of upside. At worst, his money buys him new information about his health. At best, it makes him immortal.

"The normal human lifespan is about 125 years," Grossman tells him. But Philips wasn't born until 1975, so he starts with an advantage. "I think somebody your age, and in your condition, has a reasonable chance of making it across the first bridge," Grossman says.

According to Grossman and other singularitarians, immortality will arrive in stages. First, lifestyle and aggressive antiaging therapies will allow more people to approach the 125-year limit of the natural human lifespan. This is bridge one. Meanwhile, advanced medical technology will begin to fix some of the underlying biological causes of aging, allowing this natural limit to be surpassed. This is bridge two. Finally, computers become so powerful that they can model human consciousness. This will permit us to download our personalities into nonbiological substrates. When we cross this third bridge, we become information. And then, as long as we maintain multiple copies of ourselves to protect against a system crash, we won't die.

Kurzweil himself started across the first bridge in 1988. That year, he confronted the risk that had been haunting him and began to treat his body as a machine. He read up on the latest nutritional research, adopted the Pritikin diet, cut his fat intake to 10 percent of his calories, lost 40 pounds, and cured both his high cholesterol and his incipient diabetes. Kurzweil wrote a book about his experience, The 10% Solution for a Healthy Life. But this was only the beginning.

Kurzweil met Grossman at a Foresight Nanotech Institute meeting in 1999, and they became research partners. Their object of investigation was Kurzweil's body. Having cured himself of his most pressing health problems, Kurzweil was interested in adopting the most advanced medical and nutritional technologies, but it wasn't easy to find a doctor willing to tolerate his persistent questions. Grossman was building a new type of practice, focused not on illness but on the pursuit of optimal health and extreme longevity. The two men exchanged thousands of emails, sharing speculations about which cutting-edge discoveries could be safely tried.

Though both Grossman and Kurzweil respect science, their approach is necessarily improvisational. If a therapy has some scientific promise and little risk, they'll try it. Kurzweil gets phosphatidylcholine intravenously, on the theory that this will rejuvenate all his body's tissues. He takes DHEA and testosterone. Both men use special filters to produce alkaline water, which they drink between meals in the hope that negatively charged ions in the water will scavenge free radicals and produce a variety of health benefits. This kind of thing may seem like quackery, especially when promoted by various New Age outfits touting the "pH miracle of living." Kurzweil and Grossman justify it not so much with scientific citations — though they have a few — but with a tinkerer's shrug. "Life is not a randomized, double-blind, placebo-controlled study," Grossman explains. "We don't have that luxury. We are operating with incomplete information. The best we can do is experiment with ourselves."

Obviously, Kurzweil has no plan for retirement. He intends to sustain himself indefinitely through his intelligence, which he hopes will only grow. A few years ago he deployed an automated system for making money on the stock market, called FatKat, which he uses to direct his own hedge fund. He also earns about $1 million a year in speaking fees.

Meanwhile, he tries to safeguard his well-being. As a driver he is cautious. He frequently bicycles through the Boston suburbs, which is good for physical conditioning but also puts his immortality on the line. For most people, such risks blend into the background of life, concealed by a cheerful fatalism that under ordinary conditions we take as a sign of mental health. But of course Kurzweil objects to this fatalism. He wants us to try harder to survive.

His plea is often ignored. Kurzweil has written about the loneliness of being a singularitarian. This may seem an odd complaint, given his large following, but there is something to it. A dozen of his fans may show up in Denver every month to initiate longevity treatments, but many of them, like Matt Philips, are simply hedging their bets. Most health fanatics remain agnostic, at best, on the question of immortality.

Kurzweil predicts that by the early 2030s, most of our fallible internal organs will have been replaced by tiny robots. We'll have "eliminated the heart, lungs, red and white blood cells, platelets, pancreas, thyroid and all the hormone-producing organs, kidneys, bladder, liver, lower esophagus, stomach, small intestines, large intestines, and bowel. What we have left at this point is the skeleton, skin, sex organs, sensory organs, mouth and upper esophagus, and brain."

In outlining these developments, Kurzweil's tone is so calm and confident that he seems to be describing the world as it is today, rather than some distant, barely imaginable future. This is because his prediction falls out cleanly from the equations he's proposed. Knowledge doubles every year, Kurzweil says. He has estimated the number of computations necessary to simulate a human brain. The rest is simple math.

But wait. There may be something wrong. Kurzweil's theory of accelerating change is meant to be a universal law, applicable wherever intelligence is found. It's fine to say that knowledge doubles every year. But then again, what is a year? A year is an astronomical artifact. It is the length of time required by Earth to make one orbit around our unexceptional star. A year is important to our nature, to our biology, to our fantasies and dreams. But it is a strange unit to discover in a general law.

"Doubling every year," I say to Kurzweil, "makes your theory sound like a wish."

He's not thrown off. A year, he replies, is just shorthand. The real equation for accelerating world knowledge is much more complicated than that. (In his book, he gives it as: .)

He has examined the evidence, and welcomes debate on the minor details. If you accept his basic premise of accelerating growth, he'll yield a little on the date he predicts the singularity will occur. After all, concede accelerating growth and the exponential fuse is lit. At the end you get that big bang: an explosion in intelligence that yields immortal life.

Despite all this, people continue to disbelieve. There is a lively discussion among experts about the validity of Moore's law. Kurzweil pushes Moore's law back to the dawn of time, and forward to the end of the universe. But many computer scientists and historians of technology wonder if it will last another decade. Some suspect that the acceleration of computing power has already slowed.

There are also philosophical objections. Kurzweil's theory is that super-intelligent computers will necessarily be human, because they will be modeled on the human brain. But there are other types of intelligence in the world — for instance, the intelligence of ant colonies — that are alien to humanity. Grant that a computer, or a network of computers, might awaken. The consciousness of the this fabulous AI might remain as incomprehensible to us as we are to the protozoa.

Other pessimists point out that the brain is more than raw processing power. It also has a certain architecture, a certain design. It is attached to specific type of nervous system, it accepts only particular kinds of inputs. Even with better computational speed driving our thoughts, we might still be stuck in a kind of evolutionary dead end, incapable of radical self-improvement.

And these are the merely intellectual protests Kurzweil receives. The fundamental cause for loneliness, if you are a prophet of the singularity, is probably more profound. It stems from the simple fact that the idea is so strange. "Death has been a ubiquitous, ever-present facet of human society," says Kurzweil's friend Martine Rothblatt, founder of Sirius radio and chair of United Therapeutics, a biotech firm on whose board Kurzweil sits. "To tell people you are going to defeat death is like telling people you are going to travel back in time. It has never been done. I would be surprised if people had a positive reaction."

To press his case, Kurzweil is writing and producing an autobiographical movie, with walk-ons by Alan Dershowitz and Tony Robbins. Kurzweil appears in two guises, as himself and as an intelligent computer named Ramona, played by an actress. Ramona has long been the inventor's virtual alter ego and the expression of his most personal goals. "Women are more interesting than men," he says, "and if it's more interesting to be with a woman, it is probably more interesting to be a woman." He hopes one day to bring Ramona to life, and to have genuine human experiences, both with her and as her. Kurzweil has been married for 32 years to his wife, Sonya Kurzweil. They have two children — one at Stanford University, one at Harvard Business School. "I don't necessarily only want to be Ramona," he says. "It's not necessarily about gender confusion, it's just about freedom to express yourself."

Kurzweil's movie offers a taste of the drama such a future will bring. Ramona is on a quest to attain full legal rights as a person. She agrees to take a Turing test, the classic proof of artificial intelligence, but although Ramona does her best to masquerade as human, she falls victim to one of the test's subtle flaws: Humans have limited intelligence. A computer that appears too smart will fail just as definitively as one that seems too dumb. "She loses because she is too clever!" Kurzweil says.

The inventor's sympathy with his robot heroine is heartfelt. "If you're just very good at doing mathematical theorems and making stock market investments, you're not going to pass the Turing test," Kurzweil acknowledged in 2006 during a public debate with noted computer scientist David Gelernter. Kurzweil himself is brilliant at math, and pretty good at stock market investments. The great benefits of the singularity, for him, do not lie here. "Human emotion is really the cutting edge of human intelligence," he says. "Being funny, expressing a loving sentiment — these are very complex behaviors."

One day, sitting in his office overlooking the suburban parking lot, I ask Kurzweil if being a singularitarian makes him happy. "If you took a poll of primitive man, happiness would be getting a fire to light more easily," he says. "But we've expanded our horizon, and that kind of happiness is now the wrong thing to focus on. Extending our knowledge and casting a wider net of consciousness is the purpose of life." Kurzweil expects that the world will soon be entirely saturated by thought. Even the stones may compute, he says, within 200 years.

Every day he stays alive brings him closer to this climax in intelligence, and to the time when Ramona will be real. Kurzweil is a technical person, but his goal is not technical in this respect. Yes, he wants to become a robot. But the robots of his dreams are complex, funny, loving machines. They are as human as he hopes to be.

Copyright: Wired