Stephen Hawking

21 Jan 2011

At there is a story of students flocking to hear Stephen Hawking speak at Caltech in California. He can still draw a large crowd. His speciality is quantum gravity. In 1974 he predicted that black holes should thermally create and emit subatomic particles known as Bekenstein-Hawking radiation - until they exhaust their energy and dissipate. At January 19th, 'Artificial white hole boosts Stephen Hawking's Black Hole theory' we have a story about an experiment by University of British Columbia physicists and engineers that helps bolster the Hawking theory. He said black holes are not really black - they glow like a hot body, and the smaller they are the more they glow. The temperature of a black hole varies inversely to its mass. According to the theory pairs of photons are torn apart by a black hole's gravitational field - one photon falling into the black hole and the other escaping as a form of radiation. A paper on the experiment was published by Physical Review Letters and while they don't prove Hawking's theory they show his ideas have traction.

Meanwhile, at we learn that researchers at Queen Mary University in London say they have found a way to determine the evolutionary stage of a black hole by analysing the region outside where matter cannot escape, the event horizon. It is basically mathematical science - a method based on the Kerr solution, a time-independent solution to the equations of General Relativity (paper published in The Proceedings of the Royal Society A - see ).