Black holes dissolving like aspirin: How Hawking changed physics
When Stephen Hawking postulated in the mid-1970s that black holes leak radiation, slowly dissolving like aspirin in a glass of water, he overturned a core tenet of the Universe.
Ever since Albert Einstein published his theory of general relativity in 1915, predicting the existence of black holes, it was thought they devour everything in their vicinity, including light.
Black holes, it was thought, were bottomless pits from which matter and energy could never escape.
But Hawking, sometimes described as the most influential theoretical physicist since Einstein, questioned this, saying that black holes were not really black at all and must emit particles.
In so doing, he touched on a persistent headache for physicists: Einstein's theory, which has withstood every experimental test so far, does not explain the behaviour of particles in the subatomic, "quantum" sphere.
Considered controversial at first, Hawking's black hole theory pointed to a possible bridge between the two mainstay physics theories—general relativity and quantum mechanics.
"Hawking realised that black holes, these objects that are made of gravity, because of quantum mechanics... can actually emit particles," astrophysicist Patrick Sutton of Cardiff University told AFP.
"This was the first case where we had a physical process that links gravity, this classical theory of gravity, with quantum mechanics."