Stephen Hawking has revealed that for him women are the only enduring mystery of the universe as he has not been able to crack this mystery.
This is what the cosmologist said during an interview with New Scientist magazine for his upcoming 70th birthday, when asked what he thinks about the most during the day.
"They are a complete mystery to me," CBS News quoted him as saying.
As for the world, the 69-year-old has left one mystery to be solved -how he managed to survive so long with such a crippling disease.
The physicist 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.
Lou Gehrig's disease, also called amyotrophic lateral sclerosis, or ALS, attacks motor neurons, cells that control the muscles. Patients typically suffer muscle weakness and wasting, become paralyzed and have problems talking, swallowing and breathing. Only about 10 percent of patients live longer than a decade.
People who are stricken at a young age, as Hawking was, generally have a better chance of surviving longer. Most people are diagnosed between 50 and 70. Life expectancy generally ranges from two to five years after symptoms like slurred speech, difficulty swallowing and muscle weakness set in.
For some reason, the disease has progressed more slowly in Hawking than in most.
"I don't know of anyone who's survived this long," Ammar Al-Chalabi, director of the Motor Neurone Disease Care and Research Centre at King's College London, said.
To mark his birthday on Sunday, Cambridge University is holding a public symposium on "The State of the Universe", featuring talks from 27 leading scientists, including Hawking himself.