Stephen Hawking, who has died aged 76, was one of the world's leading physicists who inspired generations of scientists
Hawking was one of the world's most acclaimed cosmologists, a medical miracle, and probably the galaxy's most unlikely superstar celebrity.
After being diagnosed with a rare form of motor neurone disease in 1964 at the age of 22, he was given just a few years to live.
Yet against all odds Professor Hawking celebrated his 70th birthday nearly half a century later as one of the most brilliant and famous scientists of the modern age.
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.
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.
He later focused 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.
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.
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