A few weeks before his 60th birthday in January 2002, Stephen Hawking had a brief flirtation with death when his electric wheelchair careered out of control and he ended up in hospital with a broken hip. Later, at a lecture entitled "Sixty years in a nutshell", arranged by Cambridge University to celebrate his birthday, Hawking displayed his customary humour when he told his audience that he had been a quantum moment away from missing the event completely. "It was nearly 59.97 years in a nutshell," he said to laughter. "I had an argument with a wall ... and the wall won."
But reported events last week have put Hawking's many accidents and injuries in a new light - and nobody is finding it funny. One of his former nurses has made serious allegations about the cosmologist's second wife, Elaine, and Cambridgeshire Police confirmed that they are investigating allegations of assault against a 62-year-old man whom they hope to interview shortly. Meanwhile, Hawking, who is in hospital recovering from pneumonia, remains resolute that there is "absolutely no substance" to the reports of his injuries and the supposed attacks. These were described in lurid detail in the same tabloid newspaper that had secured an interview with the one-time nurse, who is now living abroad.
The stakes were raised still further when Hawking's first wife, Jane, expressed her concerns - and the concerns of their three grown- up children - about the nature of her former husband's injuries. "I am extremely worried about him," she said. "He is a special man and a vulnerable man but when his children see the aftermath of these events, they can only tell him that he must do something about it."
Yet Hawking continues to keep silent, even to his closest friends and family, about who is carrying out the apparent attacks. For the first time, his son Tim publicly expressed his own uneasiness with his father's stance. "I'm very concerned. He denies it every time I speak to him about it and I would hope that he would respect me enough to tell me the truth," he said.
Anyone who knows Hawking, the Lucasian Professor of Mathematics, will testify to the man's strong, and some would say stubborn character. It is his undoubted belief in himself and his invincibility that has perhaps kept him alive 40 years after being diagnosed with motor neurone disease, when doctors gave him just a couple of years to live.
Confined to a wheelchair, unable to move anything except a few fingers and facial muscles, Hawking has become the quintessential example of a brilliant mind trapped in a broken body. Yet the author of the best-selling A Brief History of Time hates pity just as much as he loves being the centre of attention. The astounding success of his book, which has sold some 25 million copies since it was published in 1988, had led Hawking to become a household name. He made a cameo appearance in Star Trek: The Next Generation, when he was seen playing poker with Albert Einstein and Isaac Newton. Later, he was depicted drinking at a bar with Homer Simpson, suggesting that he might steal Homer's ideas on the universe being doughnut- shaped.
Hawking has visited President Clinton at the White House and counts as his friends such Hollywood stars as Jim Carey, Richard Dreyfuss and Kevin Costner. The man whose academic chair was once occupied by the puritan Newton also enjoys parties, fun and being outrageous - he was once pictured enjoying a cuddle with a raunchy blonde pole dancer at Stringfellows nightclub in London.
The media like to laud him as the greatest living scientist since Einstein and Newton, although scientists themselves …