Hawking radiation

“By applying quantum theory, he realised that some of these photons would appear to be radiated from the black hole”

Black holes got their name because their gravity is so strong that photons – or particles of light – shouldn’t be able to escape from them, rendering them dark. But in his early work on the subject, Hawking argued that the truth is more subtle than this monochrome picture.

By applying quantum theory – specifically the idea that pairs of ‘virtual photons’ can spontaneously be created out of nothing – he realised that some of these photons would appear to be radiated from the black hole. Now referred to as Hawking radiation, the theory was recently confirmed in a laboratory experiment at the Technion – Israel Institute of Technology in Haifa. In place of a real black hole, the researchers used an acoustic analogue: a ‘sonic black hole’ from which sound waves cannot escape. They detected the equivalent of Hawking radiation exactly in accordance with the physicist’s predictions.