Stephen Hawking passes away at 76; physicist was one of science's biggest celebrities since Albert Einstein

Stephen Hawking, whose brilliant mind ranged across time and space though his body was paralysed by disease, died early on Wednesday, a University of Cambridge spokesman said. He was 76 years old. Hawking died peacefully at his home in Cambridge, England.

The best-known theoretical physicist of his time, Hawking wrote so lucidly of the mysteries of space, time and black holes that his book, A Brief History of Time, became an international bestseller, making him one of science's biggest celebrities since Albert Einstein.

"He was a great scientist and an extraordinary man whose work and legacy will live on for many years," his children Lucy, Robert and Tim said in a statement.

Tributes began pouring in from scientists around the world, lauding him as an inspiration. American astrophysicist Neil deGrasse Tyson tweeted his condolences, with a characteristically cosmological reference. "His passing has left an intellectual vacuum in his wake. But it's not empty. Think of it as a kind of vacuum energy permeating the fabric of spacetime that defies measure," the scientist said.

NASA issued its own Twitter eulogy, publishing a video of the scientist grinning as he soared into weightlessness on a zero gravity flight at the Kennedy Space Center in Florida, escaping his wheelchair for a brief period of time. "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."

His death even drew mourning from celebrities not normally associated with the intricacies of astrophysics. American singer Katy Perry said there was "a big black hole in my heart".

Hawking attempted to 'know the mind of God'

Even though his body was attacked by amyotrophic lateral sclerosis, or ALS, when Hawking was 21, he stunned doctors by living with the normally fatal illness for more than 50 years. A severe attack of pneumonia in 1985 left him breathing through a tube, forcing him to communicate through an electronic voice synthesizer that gave him his distinctive robotic monotone. But he continued his scientific work, appeared on television and married for a second time.

File image of Stephen Hawking. AP

As one of Isaac Newton's successors as Lucasian Professor of Mathematics at Cambridge University, Hawking was involved in the search for the great goal of physics — a "unified theory." Such a theory would resolve the contradictions between Einstein's General Theory of Relativity, which describes the laws of gravity that govern the motion of large objects like planets, and the Theory of Quantum Mechanics, which deals with the world of subatomic particles.

For Hawking, the search was almost a religious quest — he said finding a "theory of everything" would allow mankind to "know the mind of God." "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. In later years, though, he suggested a unified theory might not exist.

The combination of his best-selling book and his almost total disability — for a while he could use a few fingers, later he could only tighten the muscles on his face — made him one of science's most recognisable faces. He made cameo television appearances in The Simpsons and Star Trek and counted among his fans U2 guitarist The Edge, who attended a January 2002 celebration of Hawking's 60th birthday. His early life was chronicled in the 2014 film The Theory of Everything, with Eddie Redmayne winning the best actor Academy Award for his portrayal of the scientist. The film focused still more attention on Hawking's remarkable achievements. Some colleagues credited that celebrity with generating new enthusiasm for science.

Although it could take him minutes to compose answers to even simple questions Hawking said the disability did not impair his work. It certainly did little to dampen his ambition to physically experience space himself: Hawking savoured small bursts of weightlessness in 2007 when he was flown aboard a jet that made repeated dives to simulate zero-gravity. Hawking had hoped to leave Earth's atmosphere altogether someday, a trip he often recommended to the rest of the planet's inhabitants. "In the long run the human race should not have all its eggs in one basket, or on one planet," Hawking said in 2008. "I just hope we can avoid dropping the basket until then."

He was unafraid of ruffling the feathers of the religious, dismissing the concept of an afterlife in a 2011 interview to The Guardian. "I have lived with the prospect of an early death for the last 49 years. I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first," he said at the time. "I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark," he added.

Birth and personal life

Hawking was born 8 January, 1942, in Oxford, and grew up in London and St. Albans, northwest of the capital. In 1959, he entered Oxford University and then went on to graduate work at Cambridge. Signs of illness appeared in his first year of graduate school, and he was diagnosed with ALS, also known as Lou Gehrig's disease after the New York Yankee star who died of it. The disease usually kills within three to five years. According to John Boslough, author of "Stephen Hawking's Universe," Hawking became deeply depressed. But as it became apparent that he was not going to die soon, his spirits recovered and he bore down on his work.

Hawking married Jane Wilde in 1965 and they had three children, Robert, Lucy and Timothy. Jane cared for Hawking for 20 years, until a grant from the United States paid for the 24-hour care he required.

Hawking divorced Jane in 1991, an acrimonious split that strained his relationship with their children. Writing in her autobiographical Music to Move the Stars, she said the strain of caring for Hawking for nearly three decades had left her feeling like "a brittle, empty shell." Hawking married his one-time nurse Elaine Mason four years later, but the relationship was dogged by rumours of abuse. Hawking and Mason separated in 2006.

With inputs from agencies