Free Public Lecture

Cracking the Einstein Code

Roy P Kerr
(University of Canterbury, NZ; and ICRANet, Italy)

Venue: Central Lecture Theatres - C3

Hosted by the Royal Society of NZ, Canterbury Branch.


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In 1963 three hundred astronomers, astrophysicists and general relativtists met in Dallas to try to explain Quasars. These newly discovered objects were extremely distant and therefore had to be enormously powerful, but no known process of conventional science was able to generate anything like the energies observed. The only hope was gravitational collapse, but the standard non-rotating Black Hole model of Schwarzschild was not enough. These Quasars were continuing to pour out incredible amounts of energy, and this could not come from inside an event horizon. Furthermore, all objects rotate, even if just slightly, and it was not clear that a rotating star could even collapse to a black hole.

In a short talk at this first Texas conference Roy Kerr announced that he had found a solution for a rotating body, and that this could represent the final gravitational field for a rotating Black Hole. Within a few years it was proved that this solution - the Kerr geometry - is unique. A Black Hole is defined completely by its mass, its spin and its electric charge. As John Wheeler was to say: "Black Holes have no hair".

Although no energy can escape from the Black Hole, it was soon realised that enormous amounts of gravitational energy can be released by an accretion disc of matter around it. It appears that all galaxies have a supermassive Black Hole at their centres and that these may have played a starring role in the creation of galaxies in the early universe.

In this lecture Professor Kerr will recount the story of rotating Black Holes, from their discovery in 1963, to present observations of supermassive Black Holes of millions - even billions - of solar masses in the centres of galaxies.


BIOGRAPHICAL SKETCH: Roy Kerr is Emeritus Professor at the University of Canterbury, and Yevgeny Lifschitz Professor at ICRANet, Italy. Born in 1934 in Kurow, and educated at the Universities of Canterbury and Cambridge, he discovered the "most important exact solution of Einstein's equations" while at the University of Texas in 1963. In 1971 he returned to the University of Canterbury as Professor of Applied Mathematics, and served as Head of the Department of Mathematics for much of the 1980s. Since his retirement in 1993 the Kerr geometry has become increasingly important in astrophysics, as technological advances have revealed rotating black holes to be key to the life cycle of the Universe. Roy is now much in demand as a public speaker. He has received the Hector Medal (1982) and the Rutherford Medal (1993) of the Royal Society of NZ, the Hughes Medal (1984) of the Royal Society London, and the Marcel Grossmann Award (2006).
Photo: © Max Alexander

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