LONDON Physicist Stephen Hawking, the author of "A Brief History of Time" who is almost completely paralyzed by motor neurone disease, has been urgently admitted to hospital, Cambridge University said on Monday.
Hawking, 67, was taken by ambulance to a local hospital in Cambridge, where he is a professor of applied mathematics and theoretical physics.
"Professor Hawking is very ill and has been taken by ambulance to Addenbrooke's Hospital," the university said.
A university spokesman said his condition was described as comfortable and that he would be kept in hospital overnight.
Hawking, who is only able to speak through a computer-generated voice synthesizer, had been ill for a couple of weeks, with his condition deteriorating since he returned from a trip to the United States at the weekend, a source said.
He canceled an appearance at Arizona State University on April 6 due to a chest infection. A pre-recorded lecture was played to a science conference instead.
He has previously been treated for pneumonia and the source said it appeared his latest illness was related to the chest infection, although he stressed there was no diagnosis yet.
The head of Cambridge's applied mathematics department expressed hope that Hawking would recover.
"Professor Hawking is a remarkable colleague," said Peter Haynes. "We all hope he will be amongst us again soon."
Hawking is renowned for his work on black holes, cosmology and quantum gravity. He achieved global recognition with the publication in 1988 of "A Brief History of Time," an account of the origins of the universe.
Hawking began suffering from motor neurone disease in his early 20s but went on to establish himself as one of the world's leading scientific authorities, and is constantly called upon to comment on new discoveries in astronomy and physics.
He raised his profile in popular culture with guest appearances in "Star Trek" and the cartoons "Futurama" and "The Simpsons." In 2007, he took a zero-gravity flight over the Atlantic Ocean in an adapted Boeing 727 jet.
Since 1974, the Oxford-educated scientist has worked on marrying the two cornerstones of modern physics -- Albert Einstein's General Theory of Relativity, which concerns gravity and large-scale phenomena, and quantum theory, which covers subatomic particles.
As a result of his research, Hawking proposed a model of the universe based on two concepts of time: "real time," or time as human beings experience it, and "imaginary time," the time on which the world may really run.
"The universe is self-contained, and without boundary, in imaginary time. However, in real time, the universe will appear to begin at the Big Bang (the explosion thought to be at the origin of the universe)," Hawking has said.
"The laws of physics will hold everywhere, so it is not necessary to believe that God intervened to set it going."
Motor neurone disease is a catch-all name for a family of muscle wasting diseases that includes amyotrophic lateral sclerosis, also known as ALS or Lou Gehrig's disease in the United States.
Although Hawking is virtually paralyzed, he has a slow-progressive form of the disease.
Hawking, who is due to step down as Cambridge's Lucasian professor of Mathematics when he turns 70, has been married twice. He has three children by his first wife.
(Reporting by Luke Baker; Editing by Charles Dick)