LONDON - Tributes from around the world began to pour in Wednesday for Stephen Hawking, one of the world's most famous scientists, who died age 76.

Hawking, an intellectual giant who became an international symbol the power of the human mind, died peacefully at his home in Cambridge, England.

The celebrated British physicist probed the mysteries of the cosmos and helped to popularize science with books like "A Brief History of Time," an international bestseller.

When he was just 21, he was diagnosed with a rare form of motor neuron disease and told by doctors he had only a few years to live. His illness left him unable to move a muscle and he could only talk with the help of a voice synthesizer.

On Wednesday morning, "Stephen Hawking" was trending worldwide on social media.

NASA, the U.S. space agency, tweeted: "His theories unlocked a universe of possibilities that we & the world are exploring. May you keep flying like superman in microgravity, as you said to astronauts on @Space_Station in 2014."

The founder of the World Wide Web, Tim Berners-Lee said: "We have lost a colossal mind and a wonderful spirit."

Canadian astronaut Chris Hadfield tweeted: "Genius is so fine and rare. Goodbye Professor Hawking. You inspired and taught us all."

"We lost a great one today," wrote Satya Nadella, the CEO of Microsoft.

The astrophysicist Neil deGrasse Tyson said his passing had "left an intellectual vacuum."

It wasn't just the scientists that mourned his passing, but tributes came from 10 Downing Street as well, where the prime minister's account celebrated him as an "inspiration" and one of the "great scientists of his generation."

Hawking also was a cultural phenomena, appearing on shows like "The Simpsons" and "The Big Bang Theory" as well as an episode "Star Trek: The Next Generation" in which he played poker with actors portraying Albert Einstein and Isaac Newton. Films were also made about his life, including "The Theory of Everything," which saw Eddie Redmayne win an Oscar for his portrayal of Hawking.

Hawking was also known for his wit and sense of humor. Jonathan McDowell, an astrophysicist at Harvard, recalled that when he gave lectures he would add in jokes even when it was difficult for him to speak. "I recall when we has giving lectures and it was a huge effort for him to speak (before the tracheotomy and the computer voice) he still made the effort to throw jokes in. That says something," McDowell wrote on Twitter.

Author Information: Karla Adam is a London correspondent for The Washington Post. Before joining The Post in 2006, she worked as a freelancer in London for the New York Times and People magazine.