CAMBRIDGE, England — British scientist Stephen Hawking has decoded some of the most puzzling mysteries of the universe but he has left one mystery unsolved: how he has managed to survive so long with such a crippling disease.
The physicist and cosmologist was diagnosed with Lou Gehrig's disease when he was a 21-year-old student at Cambridge University. Most people die within a few years of the diagnosis, called motor neurone disease in the U.K. On Sunday, Hawking will turn 70.
"I don't know of anyone who's survived this long," said Ammar Al-Chalabi, director of the Motor Neurone Disease Care and Research Centre at King's College London. He doesn't treat Hawking and described his longevity as "extraordinary."
Hawking first gained attention with his 1988 book A Brief History of Time, a simplified overview of the universe.
To mark his birthday Sunday, Cambridge University is holding a public symposium on "The State of the Universe," featuring talks from 27 leading scientists, including Hawking. For 30 years, he held a mathematics post at the university previously held by Sir Isaac Newton. Hawking retired from that position in 2009 and is now director of research at the university's Centre for Theoretical Cosmology.
Hawking achieved all that despite being nearly entirely paralyzed and in a wheelchair since 1970. He now communicates only by twitching his right cheek. Since catching pneumonia in 1985, Hawking has needed around-the-clock care and relies on a computer and voice synthesizer to speak.
Hawking says he tries not to think about his limitations.
"I have had (Lou Gehrig's disease) for practically all my adult life," he says on his website. "Yet it has not prevented me from having a very attractive family and being successful in my work."
Hawking has been married twice and has three children and three grandchildren.