At MIT last week, Ray Kurzweil described a future in which he’s convinced immortality — or a drastically longer life span — will be possible thanks to emerging technologies.

His new book, coauthored with Terry Grossman, M.D., “Fantastic Voyage: Live Long Enough to Live Forever,” outlines a special “longevity program” of diet, exercise and nutritional supplements .

“I really do believe it is feasible to slow down the aging process,” Kurzweil told the MIT Emerging Technologies Conference. He said he believes science will develop therapies to stop and even reverse aging within 10 to 20 years, thanks to advances in biotechnology and nanotechnology.

He described three stages or “bridges” on the road to radical life extension. First is his and Dr. Grossman’s healthy living program designed to correct “metabolic imbalances” and keep even baby boomers alive long enough to benefit from the second stage.

In stage two, a decade or so away, he contends biotechnology advances will block diseases and dramatically slow aging, because the decoding of our genome is already leading to tissue-engineering techniques for regrowing cells and organs, and to the creation of genetically targeted drugs and gene therapies.

These techniques, he said, will help many people reach the third stage — about 20 to 25 years away — when nanotechnology will allow humans to radically rebuild and extend their bodies with help from “nanobots,” robots that will slip into our bloodstreams to fix DNA errors, fight pathogens and expand intelligence.

At that point, he declared, we will have achieved radical life extension.