Physicist Stephen Hawking was hospitalized overnight for a chest infection but his family "is looking forward" to a full recovery, Cambridge University said Tuesday.
Hawking "was being kept in observation" at Addenbrooke's hospital after being admitted Monday.
"He is comfortable and his family is looking forward to him making a full recovery," the university said in a statement.
The statement did not indicate Hawking's condition and the hospital declined to comment.
Hawking, 67, gained renown for his work on black holes and has remained active despite being diagnosed at age 21 with ALS, (amyotrophic lateral sclerosis), an incurable degenerative disorder also known as Lou Gehrig's disease.
Hawking has been almost entirely paralyzed for years and communicates through an electronic voice synthesizer activated by his fingers.
Hawking has searched for a major goal of physics — a "unified theory" — to solve contradictions between Albert Einstein's General Theory of Relativity, which explains the laws of gravity that control the motion of large objects like planets, and the Theory of Quantum Mechanics, which deals with 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 A Brief History of Time, his best-selling book published in 1988.
In the sequel The Universe in a Nutshell, published in 2001, Hawking looked into concepts such as supergravity and the possibility of a universe with 11 dimensions.
"He is amazingly resilient," said Andrew Fabian, the head of the Royal Astronomical Society and a professor of astronomy at Cambridge. "He goes around the world — he does more traveling than most of us. ... And he just seems unstoppable. It's truly amazing."
Hawking did announce last year that he would no longer hold his post as Lucasian Professor of Mathematics, a title that 18th-century physicist Isaac Newton once had. Because the university said Monday that Hawking intended to continue working as Emeritus Lucasian Professor of Mathematics, Fabian said that he thinks Hawking will "carry on and do just the same."
The chest infection, which Hawking has been fighting for several weeks, had caused him to cancel an appearance at Arizona State University on April 6.