Cambridge University says physicist Stephen Hawking is still hospitalized but recovering from a chest infection.
The university said Wednesday that Hawking is “on the road to recovery” from the illness that has kept him at Addenbrooke’s Hospital in Cambridge since earlier this week.
The 67-year-old scientist is well-known for his work on black holes and his best-selling 1988 book “A Brief History of Time.”
Hawking has remained active even though he was diagnosed at age 21 with ALS (amyotrophic lateral sclerosis), an incurable degenerative disorder also known as Lou Gehrig’s disease.
He has been almost completely paralyzed for years and communicates through an electronic voice synthesizer activated by twitches of his cheek muscles.
Hawking has been involved in the search for the great goal of physics — a so-called "unified theory" or "theory of everything" that 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 the sequel "The Universe in a Nutshell," published in 2001, Hawking ventured into concepts like supergravity, naked singularities and the possibility of a universe with 11 dimensions.
One of Hawking's best-known scientific contributions is the theoretical claim that black holes would gradually dissipate due to an effect now known as "Hawking radiation." The theory surrounding the existence of Hawking radiation has played a part in the discussion over whether mini-black holes created by Europe's Large Hadron Collider might destroy the world. (Scientists say they wouldn't.)
Hawking 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 has said that Hawking intended to continue working as Emeritus Lucasian Professor of Mathematics.
Hawking has also accepted a research position at the Perimeter Institute for Theoretical Physics in Canada. He is collaborating with his daughter, Lucy Hawking, on a series of children's books. And next year, the Discovery Channel is set to air a TV series on his life and work titled "Stephen Hawking's Universe."
Hawking has been fighting his chest infection for several weeks, and illness caused him to cancel an appearance at Arizona State University on April 6. At the time, Hawking joked that his doctors advised him not to travel, "so I thought about getting some new doctors."
This report includes information from The Associated Press and msnbc.com.