Stephen Hawking, the British mathematician and physicist famed for his work on black holes, was rushed to a hospital Monday and was seriously ill, Cambridge University said.
Hawking has been fighting a chest infection for several weeks and was being treated at Addenbrooke’s Hospital in Cambridge, the university city northeast of London, the university said.
“Professor Hawking is very ill,” said Gregory Hayman, the university’s head of communications. “He is undergoing tests. He has been unwell for a couple of weeks.”
Later in the afternoon, Hayman said Hawking was “now comfortable but will be kept in hospital overnight.”
Hawking, 67, has remained active despite being diagnosed at 21 with ALS (amyotrophic lateral sclerosis), an incurable degenerative disorder also known as Lou Gehrig's disease. Brian Dickie, director of research at the Motor Neurone Disease Association, said only 5 percent of people diagnosed with ALS survive for 10 years or longer.
For some years, Hawking has been almost entirely paralyzed, and he communicates through an electronic voice synthesizer activated by twitches of his cheek muscles.
Hawking was involved in the search for the great goal of physics — a so-called "unified field theory" or "theory of everything" — which would resolve contradictions between Albert Einstein's general theory of relativity, which describes the laws of gravity that govern the motion of large objects like planets, and quantum theory, which deals with the world of subatomic particles.
"A complete, consistent unified theory is only the first step: our goal is a complete understanding of the events around us, and of our own existence," he wrote in his best-selling book, "A Brief History of Time," published in 1988.
In a more accessible sequel, "The Universe in a Nutshell," published in 2001, Hawking ventured into concepts like supergravity, naked singularities and the possibility of a universe with extra unseen dimensions.
He announced last year that he would step down from his post as Lucasian Professor of Mathematics, a title once held by the great 18th-century physicist Isaac Newton. However, the university said Hawking intended to continue working as Emeritus Lucasian Professor of Mathematics. Hawking has also accepted a research post at the Perimeter Institute for Theoretical Physics in Ontario, which would involve regular visits to Canada.
Hawking had canceled an appearance at Arizona State University on April 6 because of his illness. At the time, he was visiting California for a series of lectures and told the Arizona audience in a recorded message that he had to limit his travel. "My doctors have insisted that I do not fly, so I thought about getting some new doctors," he joked.
The scientist suffered a similar medical crisis in 2005 during a U.S. tour, but recovered well enough to resume a sometimes-grueling work routine. In 2007, he took a widely publicized zero-gravity flight and vowed that he would follow up with a suborbital trip into outer space. He is also writing a series of children's books with his daughter, Lucy Hawking, and is working on a TV project for the Discovery Channel that is due to air in 2010.
On Monday, his friends and colleagues voiced hopes that he would bounce back once again.
"Professor Hawking is a remarkable colleague. We all hope he will be amongst us again soon," said Professor Peter Haynes, head of Cambridge's Department of Applied Mathematics and Theoretical Physics.
This report includes information from The Associated Press and msnbc.com.