"The futuristic landscapes that Mr Kurzweil paints have often been derided as outlandish. Nevertheless, he says he stands by his record. In his first book, "The Age of Intelligent Machines", published in 1990, he predicted that in just a few years a global computer network would emerge. In late 1993, the web hit the mainstream and never looked back. He also predicted that a computer would defeat a chess champion by 1999: sure enough, IBM's Deep Blue defeated Garry Kasparov in 1997. "Well," shrugs Mr Kurzweil, "I was off by a couple of years."

'All of which leads to the 57-year-old Mr Kurzweil's most outrageous prediction: immortality. In his new book, "Fantastic Voyage: Live Long Enough to Live Forever", he and his co-author argue, in sometimes dense scientific detail, that death no longer need be a fact of life. Current advances in medicine, they say, will lead to major breakthroughs in genetics between 2015 and 2020 that will extend life spans. Then, by the late 2020s, advances in nanotechnology will make possible truly radical life extension and rejuvenation. So to achieve immortality, people alive today merely need to survive long enough to reach the first of these breakthroughs, which will in turn enable them to benefit from the second."