Famed physicist Stephen Hawking expires at 76

World renowned physicist Stephen Hawking has died at the age of 76, report agencies.

He died peacefully at his home in the British university city of Cambridge in the early hours of Wednesday.

The British scientist was famed for his work with black holes and relativity, and wrote several popular science books including A Brief History of Time.

At the age of 22 Prof Hawking was given only a few years to live after being diagnosed with a rare form of motor neurone disease.

The illness left him in a wheelchair and largely unable to speak except through a voice synthesiser.

In a statement his children, Lucy, Robert and Tim, said: "We are deeply saddened that our beloved father passed away today.

"He was a great scientist and an extraordinary man whose work and legacy will live on for many years."

They praised his "courage and persistence" and said his "brilliance and humour" inspired people across the world.

"He once said, 'It would not be much of a universe if it wasn't home to the people you love.' We will miss him forever."

Hawking's formidable mind probed the very limits of human understanding both in the vastness of space and in the bizarre sub-molecular world of quantum theory, which he said could predict what happens at the beginning and end of time.

His work ranged from the origins of the universe, through the tantalising prospect of time travel to the mysteries of space's all-consuming black holes.

Prof Hawking was the first to set out a theory of cosmology as a union of relativity and quantum mechanics.

He also discovered that black holes leak energy and fade to nothing - a phenomenon that would later become known as Hawking radiation.

Through his work with mathematician Sir Roger Penrose he demonstrated that Einstein's general theory of relativity implies space and time would have a beginning in the Big Bang and an end in black holes.

The scientist gained popularity outside the academic world and appeared in several TV shows including The Simpsons, Red Dwarf and The Big Bang Theory.

He was portrayed in both TV and film, recently by Oscar winner Eddie Redmayne in The Theory of Everything, which charted his rise to fame and relationship with his first wife, Jane.

The actor paid tribute to him, saying: "We have lost a truly beautiful mind, an astonishing scientist and the funniest man I have ever had the pleasure to meet.

"My love and thoughts are with his extraordinary family."

The power of his intellect contrasted cruelly with the weakness of his body. The disease spurred him to work harder but also contributed to the collapse of his two marriages, he wrote in a 2013 memoir "My Brief History."

Hawking shot to international fame after the 1988 publication of ""A Brief History of Time", one of the most complex books ever to achieve mass appeal, which stayed on the Sunday Times best-sellers list for no fewer than 237 weeks.

He said he wrote the book to convey his own excitement over recent discoveries about the universe.

""My original aim was to write a book that would sell on airport bookstalls," he told reporters at the time. ""In order to make sure it was understandable I tried the book out on my nurses. I think they understood most of it."

He was particularly proud that the book contains only one mathematical equation - relativity's famous E=MC squared.

"We have lost a colossal mind and a wonderful spirit," said Tim Berners-Lee, the inventor of the World Wide Web. "Rest in peace, Stephen Hawking."

Hawking's popular recognition became such that he appeared as himself on the television show "Star Trek: Next Generation" and his cartoon caricature appeared on "The Simpsons".

A 2014 film, The Theory of Everything, with Eddie Redmayne playing Hawking, charted the onset of his illness and his early life as the brilliant student grappling with black holes and the concept of time.

Since 1974 he worked extensively on marrying the two cornerstones of modern physics - Einstein's General Theory of Relativity, which concerns gravity and large-scale phenomena, and quantum theory, which covers subatomic particles.

As a result of that research, Hawking proposed a model of the universe based on two concepts of time: ""real time", or time as human beings experience it, and "quantum theory's "imaginary time", on which the world may really run.

"Imaginary time may sound like science fiction ... but it is a genuine scientific concept," he wrote in a lecture paper.

Real time could be perceived as a horizontal line, he said.

"On the left, one has the past, and on the right, the future. But there's another kind of time in the vertical direction. This is called imaginary time, because it is not the kind of time we normally experience - but in a sense, it is just as real as what we call real time."

In July 2002, Hawking said in a lecture that although his quest was to explain everything, a theory of determinism that would predict the universe in the past and forever in the future probably could not be achieved.

While his intellectual prowess was what made Hawking a hero for many, it was also his poignant outlook on his own mortality and life, and his unwavering ability to solely look at logic and reason when he stared death in the face daily. He was a hero for atheists.

There was one point where religious advocates tried to use a quote from A Brief History Of Time to suggest his belief in God: "It would be the ultimate triumph of human reason - for then we should know the mind of God." However, if it wasn't clear to people that he was an atheist, in his 2010 book The Grand Design he clarified that it was a metaphorical comment. He later told El Mundo in no uncertain terms: "What I meant by 'we would know the mind of God' is, we would know everything that God would know, if there were a God. Which there isn't. I'm an atheist."

Hawking had to aggressively face his own mortality every single day, it would have been understandable for him to abandon evidential reasoning and fall into the old adage that there are "no atheists in a foxhole." Instead, he continued to approach his stance on religion with scientific evidence-based reasoning. He also wasn't afraid to call out what he saw as fictitious stories:

Science predicts that many different kinds of universe will be spontaneously created out of nothing. It is a matter of chance which we are in. 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.

But more than anything, he didn't have to say much to poignantly highlight how life as an atheist can mean having a voracious appetite to achieve, find value and meaning in every hour of the day, and realize that facts are beautiful enough without the "fairy tales:"

Science is beautiful when it makes simple explanations of phenomena or connections between different observations. Examples include the double helix in biology, and the fundamental equations of physics.

We should seek the greatest value of our action. 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.