Professor Stephen Hawking, one of the world's most eminent physicists, has admitted that women number among black holes and supersymmetry as one of the greatest mysteries in the universe.
In an interview with New Scientist magazine ahead of his 70th birthday on Sunday, Hawking was asked what he thinks about most during the day.
"Women," he replied. "They are a complete mystery".
Hawking was diagnosed with motor neurone disease at the age of 21, and was expected to live for just a few years.
Since his diagnosis Hawking has gone on to become one of the world's most famous scientists, both for his academic work on black holes and his books including A Brief History Of Time, which has sold more than 10m copies since 1988.
In the interview with New Scientist, Hawking also refers to the "blunders" that have blighted his academic and also his personal life.
"I used to think that information was destroyed in black holes," he said. "That was my biggest blunder, or at least my biggest blunder in science."
Asked to list the most exciting developments in science in his career, Hawking discusses recent evidence discovered that appear to confirm the theory of inflation - the idea that the universe underwent a period of sudden expansion after the big bang.
He also says that if he were starting out as a physicist today, he would again try to seek out new areas of study.
"I would have a new idea that would open up a new field," he said.
Hawking's birthday will be marked by a three-day conference which starts on Friday at the University of Cambridge and culminates on 8 January with a public symposium on the "State of the Universe".
The conference will be available to watch free of charge online.
The Science Museum has released two newly commissioned photographs of Hawking taken by Sarah Lee in honour of his birthday.
The pictures will go on show at the museum on 20 January.
Roger Highfield, director of external affairs at the Science Museum, said: "[Hawking] has done more than anyone else I can think of to popularise these extraordinary ideas, inspiring both the public and the next generation of scientists."
Suggested For You
SUBSCRIBE AND FOLLOW
Get top stories and blog posts emailed to me each day. Newsletters may offer personalized content or advertisements.Learn more