Stephen Hawking death: The discovery on black holes that made him the most famous scientist in the world, explained

Stephen Hawking has died, leaving behind him a body of scientific work that shone a light on the darkest parts of the universe.

The Cambridge professor and physicist became famous for his work on the Hawking radiation that took his name. The discovery at the heart of that phenomenon was a simple one – black holes are not completely black, but glow with specific kinds of radiation – but it was one that entirely changed our picture of the universe and where it was going.

Professor Hawking was famous as much for his explanations and advocacy as he was for his work. But the work itself was profound and grand, changing our understanding of black holes and some of the strangest phenomena in existence.

The central part of that work was his discoveries about Hawking radiation. That idea is still only theoretical – if it had been proven, as it may well soon be, Professor Hawking would have been very likely indeed to have won the Nobel prize – but it is now the beginning of a deep and technical body of work.

Hawking radiation was first outlined in 1974. It describes strange effects that should be visible especially around very small black holes, where radiation would be thrown out.

"Stephen’s ‘eureka moment' revealed a profound and unexpected link between gravity and quantum theory: he predicted that black holes would not be completely black, but would radiate in a characteristic way," said Martin Rees, astronomer royal, fellow of Trinity College, emeritus professor of cosmology and astrophysics at the University of Cambridge and a longtime associate of Professor Hawking.

"Bekenstein’s concept that black holes had ‘entropy’ was more than just an analogy. This radiation is only significant for black holes much less massive than stars – and none of these have been found. However ‘Hawking radiation’ had very deep implications for mathematical physics – indeed one of the main achievements of string theory has been to corroborate his idea. It is still the focus of theoretical interest – a topic of debate and controversy more than 40 years after his discovery."

Much work has been done to turn that theoretical interest and exploration into practical observation. But because black holes are so very difficult to observe and appear in such extreme ways, it hasn't yet been possible to see the glow of radiation that is expected to surround them.

That doesn't mean such proof will not ever be found. Work including CERN's Large Hadron Collider and the discovery of gravitational waves have shed new light onto black holes, and it's very possible that Professor Hawking's famous idea will be observed in the coming years.

Professor Hawking went on to explore the implications and specifics of his discovery right up until his later years. They included fascinating insights into how exactly black holes destroyed and retained information – discoveries that led him to say, for instance, that black holes might serve as a passageway into another universe, if you could possibly survive being hurled into one.