Stephen Hawking, a renowned British theoretical physicist and cosmologist who sought to explain the universe to millions, died Tuesday at the age of 76, his family said late Tuesday.

"We are deeply saddened that our beloved father passed away today," his children said in a statement to Sky News.  "He was a great scientist and an extraordinary man whose work and legacy will live on for many years."

Hawking was perhaps the most famous scientist of his time. His work focused black holes -- dying stars that have collapsed upon themselves, forming a core of such density and strong gravitational attraction that nothing -- not even light -- can escape from it

He also made the theoretical prediction that black holes emit radiation that would eventually evaporate, often referred to as Hawking radiation. At first he thought his 1970 discovery actually the result of a mistake in his calculation. But he was eventually persuaded that his formula was accurate.

"I would like this simple formula to be on my tombstone," he said at his 60th birthday celebration in 2002.

His 1988 book "A Brief History of Time" was written in a manner to explain the origin and expansion of the universe to readers unfamiliar with scientific theories. It was enormously popular, selling more than 10 million copies and translated into 35 languages. It also spawned similar books by Hawking:  "The Universe in a Nutshell" and "A Briefer History of Time."

His passing brought out tributes from the scientific community lauding Hawking's contribution to a better understanding of the universe.

"His passing has left an intellectual vacuum in his wake," astrophycist Neil deGrasse Tyson wrote in a tweet. "But it's not empty. Think of it as a kind of vacuum energy permeating the fabric of spacetime that defies measure. Stephen Hawking, RIP 1942-2018."

Paul Saffo, a Silicon Valley technology forecaster, tweeted that "Stephen Hawking has joined Einstein -- lets hope both are offering the Old One advice re how to fix this messed-up universe."

Hawking suffered from a form of amyotrophic lateral sclerosis known as Lou Gehrig's disease that gradually paralyzed him since he was first diagnosed at age 21. He stunned many by living 50 years beyond the two years doctors had predicted.

Hawking, who spoke through a computer system operated with his cheek, also had a keen ability to create memorable phrases to sum up his views on the world.

"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge," he once said.

He also called theology "unnecessary.

"I believe the simplest explanation is, there is no God," he said. "No one created the universe and no one directs our fate. This leads me to a profound realization that there probably is no heaven and no afterlife either. We have this one life to appreciate the grand design of the universe and for that, I am extremely grateful."

His early life was chronicled in the 2014 film "The Theory of Everything," which won an Oscar for Eddie Redmayne, the actor who portrayed Hawking. He also made cameo appearances on TV shows "The Big Bang Theory," "The Simpsons" and "Star Trek."

Popularity aside, he rejected the notion he was coming of Albert Einstein as "media hype.

"I fit the part of a disabled genius," he told the Los Angeles Times in 1990. "At least, I'm disabled -- even though I'm not a genius like Einstein. ... The public wants heroes. They made Einstein a hero, and now they're making me a hero, though with much less justification."

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