Stephen Hawking has died aged 76.

It was more than 50 years after he was, at the age of 22, 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.

Against all odds, Professor Hawking celebrated his 70th birthday as one of the most brilliant and famous scientists of the modern age.

He became one of the world's most acclaimed cosmologists, a medical miracle, and probably the galaxy's most unlikely superstar celebrity. He wrote a plethora of scientific papers that earned him comparisons with Albert Einstein and Sir Isaac Newton.

At the same time he embraced popular culture with enthusiasm and humour, appearing in TV cartoon The Simpsons, starring in Star Trek and providing the voice-over for a British Telecom commercial that was later sampled on rock band Pink Floyd's The Division Bell album.

Renowned British Physicist Stephen Hawking has passed away at his home in Cambridge, March 14, 2018.
Renowned British Physicist Stephen Hawking has passed away at his home in Cambridge, March 14, 2018.

His rise to fame and relationship with his first wife, Jane, was dramatised in a 2014 film, The Theory Of Everything, in which Eddie Redmayne put in an Oscar-winning performance as the physicist battling with a devastating illness.

He was best known for his work on black holes, the mysterious infinitely dense regions of compressed matter where the normal laws of physics break down, which dominated the whole of his academic life.

Prof Hawking's crowning achievement was his prediction in the 1970s that black holes can emit energy, despite the classical view that nothing - not even light - can escape their gravity.

Hawking Radiation, based on mathematical concepts arising from quantum mechanics, the branch of science that deals with the weird world of sub-atomic particles, eventually causes black holes to "evaporate" and vanish, according to the theory.

Had the existence of Hawking Radiation been proved by astronomers or physicists, it would almost certainly have earned Prof Hawking a Nobel Prize. As it turned out, the greatest scientific accolade eluded him until the time of this death.

Stephen Hawking: Quotes from one of the world's most famous scientists

On the reason why the universe exists: "If we find the answer to that, it would be the ultimate triumph of human reason - for then we would know the mind of God" - A Brief History Of Time, published 1988

On being diagnosed with motor neurone disease: "My expectations were reduced to zero when I was 21. Everything since then has been a bonus" - Interview in The New York Times, December 2004

On black holes: "Einstein was wrong when he said, 'God does not play dice'. Consideration of black holes suggests, not only that God does play dice, but that he sometimes confuses us by throwing them where they can't be seen" - The Nature Of Space And Time, published 1996

On God: "It is not necessary to invoke God to light the blue touch paper and set the universe going" - The Grand Design, published 2010

On commercial success: "I want my books sold on airport bookstalls" - Interview in The New York Times, December 2004

On fame: "The downside of my celebrity is that I cannot go anywhere in the world without being recognised. It is not enough for me to wear dark sunglasses and a wig. The wheelchair gives me away" - Interview on Israeli TV, December 2006.

On an imperfect world: "Without imperfection, you or I would not exist" - In Into The Universe With Stephen Hawking, The Discovery Channel, 2010.

On euthanasia: "The victim should have the right to end his life, if he wants. But I think it would be a great mistake. However bad life may seem, there is always something you can do, and succeed at. While there's life, there is hope" - Quoted in People's Daily Online, June 2006.

On intellectual showboating: "People who boast about their IQ are losers" - Interview in The New York Times, December 2004.

On the possibility of contact between humans and aliens: "I think it would be a disaster. The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low" - In Naked Science: Alien Contact, The National Geographic Channel, 2004.

On the importance of having a sense of humour: "Life would be tragic if it weren't funny" - Interview in The New York Times, December 2004.

On death: "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" - Interview in The Guardian, May 2011.

Born in Oxford on January 8 1942 - 300 years after the death of astronomer Galileo Galilei - Prof Hawking grew up in St Albans.

He had a difficult time at the local public school and was persecuted as a "swot" who was more interested in jazz, classical music and debating than sport and pop.

Although not top of the class, he was good at maths and "chaotically enthusiastic in chemistry".

Professor Stephen Hawking, who has died aged 76, attending the UK premiere of The Theory of Everything at the Odeon Leicester Square, London. PRESS ASSOCIATION
Professor Stephen Hawking, who has died aged 76, attending the UK premiere of The Theory of Everything at the Odeon Leicester Square, London. PRESS ASSOCIATION

As an undergraduate at Oxford, the young Hawking was so good at physics that he got through with little effort.

He later calculated that his work there "amounted to an average of just an hour a day" and commented: "I'm not proud of this lack of work, I'm just describing my attitude at the time, which I shared with most of my fellow students.

"You were supposed to be brilliant without effort, or to accept your limitations and get a fourth-class degree."

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Hawking got a first and went to Cambridge to begin work on his PhD, but already he was beginning to experience early symptoms of his illness.

During his last year at Oxford he became clumsy, and twice fell over for no apparent reason. Shortly after his 21st birthday he went for tests, and at 22 he was diagnosed with amyotrophic lateral sclerosis (ALS), a form of motor neurone disease.

The news came as an enormous shock that for a time plunged the budding academic into deep despair. But he was rescued by an old friend, Jane Wilde, who went on to become his first wife, giving him a family with three children.

After a painful period coming to terms with his condition, Prof Hawking threw himself into his work.

Renowned British Physicist Stephen Hawking has passed away at his home in Cambridge, March 14, 2018
Renowned British Physicist Stephen Hawking has passed away at his home in Cambridge, March 14, 2018

At one Royal Society meeting, the still-unknown Hawking interrupted a lecture by renowned astrophysicist Sir Fred Hoyle, then at the pinnacle of his career, to inform him that he had made a mistake.

An irritated Sir Fred asked how Hawking presumed to know that his calculations were wrong. Hawking replied: "Because I've worked them out in my head."

In the 1980s, Prof Hawking and Professor Jim Hartle, from the University of California at Santa Barbara, proposed a model of the universe which had no boundaries in space or time.

The concept was described in his best-selling popular science book A Brief History Of Time, published in 1988, which sold 25 million copies worldwide.

Nasa remembers Stephen Hawking as 'renowned physicist and ambassador of science'

Tributes to Professor Stephen Hawking have been pouring out around the world after the celebrated physicist's death at 76.

He died peacefully at his home in Cambridge in the early hours of Wednesday morning.

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. His courage and persistence with 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."

Nasa remembered Prof Hawking as a "renowned physicist and ambassador of science". The organisation said: "His theories unlocked a universe of possibilities that we and the world are exploring. May you keep flying like superman in microgravity, as you said to astronauts on Space Station in 2014."

Indian prime minister Narendra Modi said Prof Hawking had "made the world a better place" and his death was "anguishing".

"Professor Stephen Hawking was an outstanding scientist and academic. His grit and tenacity inspired people all over the world," a tweet on his page said.

US astrophysicist Neil deGrasse Tyson was one of the first to pay tribute to Prof Hawking. Sharing a photo of himself and Prof Hawking on Twitter, he said the scientist's death has "left an intellectual vacuum in his wake".

He added: "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."

Sean Carroll, a physics professor at US university Caltech, said: "Stephen Hawking was the rare famous scientist who deserved every bit of his fame. A brilliant physicist and an inspirational person. And quite a character."

Greenpeace USA thanked Prof Hawking for helping people understand their place in the universe and for "leaving us in awe and wonder".

Celebrities also paid tribute, with US singer Katy Perry saying his death left a "big black hole in my heart".

The rock band Foo Fighters tweeted: "'Remember to look up at the stars and not down at your feet' - RIP Stephen Hawking you f****** legend."

As well as razor sharp intellect, Prof Hawking also possessed an almost child-like sense of fun, which helped to endear him to members of the public.

He booked a seat on Sir Richard Branson's Virgin Galactic sub-orbital space plane and rehearsed for the trip by floating inside a steep-diving Nasa aircraft - dubbed the "vomit comet" - used to simulate weightlessness.

On one wall of his office at Cambridge University was a clock depicting Homer Simpson, whose theory of a "doughnut-shaped universe" he threatened to steal in an episode of the cartoon show. He is said to have glared at the clock whenever a visitor was late.

From 1979 to 2009 he was Lucasian Professor of Mathematics at the university - a post once held by Sir Isaac Newton. He went on to become director of research in the university's Department of Applied Mathematics and Theoretical Physics.

Eddie Redmayne and Professor Stephen Hawking, who has died aged 76, arriving at the After-party dinner for the EE British Academy Film Awards at Grosvenor House Hotel in London.
Eddie Redmayne and Professor Stephen Hawking, who has died aged 76, arriving at the After-party dinner for the EE British Academy Film Awards at Grosvenor House Hotel in London.

Upheaval in his personal life also hit the headlines, and in February 1990 he left Jane, his wife of 25 years, to set up home with one of his nurses, Elaine Mason. The couple married in September 1995 but divorced in 2006.

Throughout his career Prof Hawking was showered with honorary degrees, medals, awards and prizes, and in 1982 he was made a CBE.

But he also ruffled a few feathers within the scientific establishment with far-fetched statements about the existence of extraterrestrials, time travel, and the creation of humans through genetic engineering.

He has also predicted the end of humanity, due to global warming, a new killer virus, or the impact of a large comet.

Queen Elizabeth II meeting Professor Stephen Hawking, who has died aged 76, during a reception for Leonard Cheshire Disability in the State Rooms, St James's Palace, London.
Queen Elizabeth II meeting Professor Stephen Hawking, who has died aged 76, during a reception for Leonard Cheshire Disability in the State Rooms, St James's Palace, London.

In 2015 he teamed up with Russian billionaire Yuri Milner who has launched a series of projects aimed at finding evidence of alien life.

The decade-long Breakthrough Listen initiative aims to step up the Search for Extraterrestrial Intelligence (Seti) by listening out for alien signals with more sensitivity than ever before.

The even bolder Starshot Initiative, announced in 2016, envisages sending tiny light-propelled robot space craft on a 20-year voyage to the Alpha Centauri star system.

Meanwhile Prof Hawking's "serious" work continued, focusing on the thorny question of what happens to all the information that disappears into a black hole. One of the fundamental tenets of physics is that information data can never be completely erased from the universe.

Professor Stephen Hawking, who has died aged 76
Professor Stephen Hawking, who has died aged 76

A paper co-authored by Prof Hawking and published online in Physical Review Letters in June 2016 suggests that even after a black hole has evaporated, the information it consumed during its life remains in a fuzzy "halo" - but not necessarily in the proper order.

Prof Hawking outlined his theories about black holes in a series of Reith Lectures broadcast on BBC Radio 4 in January and February 2016.