Kerr solution for Australian students

June 2010

 

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Black hole scientist inspires students to aim for the stars

Western Australian school students and teachers met black hole discoverer emeritus professor Roy Kerr when he visited the University of Western Australia and the Gravity Discovery Centre in Gingin recently.

In 1963 the New Zealand mathematician cracked Einstein’s equations which describe the space outside a rotating star or black hole. Kerr created a revolution in astrophysics with a discovery said to be the most important solution to any equation in physics. He was at the University of Texas at the time, and is now at Canterbury University’s department of physics and astronomy.

According to Nobel laureate, astrophysicist Professor S. Chandrasekhar, Kerr provided “the absolutely exact representation of untold numbers of massive black holes that populate the universe”. American theoretical physicist professor Louis Witten said professor Kerr’s work described “the fate of all the stars in the universe”.

The Kerr solution has since been pivotal in deepening scientists’ understanding of astrophysics and gravitation. The rotation of Kerr black holes has been shown to be a possible explanation for some of the most violent and energetic phenomena in the universe, such as supernovae producing gamma ray bursts, and jets in active galactic nuclei. Many new effects arise in the Kerr solution – a rotating object drags space with it, in a way which would not be possible in Newton’s theory.

Recent astronomical observations provide strong evidence for the existence of Kerr black holes. In future, the Kerr solution will contribute to the understanding of the signatures of gravitational waves.

Professor Kerr talked to secondary science teachers and students as part of the University of Western Australia’s Secondary Teachers’ Enrichment Program.

Making space

The organisers of an educators’ programme in Houston, Texas, may be a little presumptuous in claiming space travel as “education’s final frontier” in their information material, but there will be interest in the professional development programme they have put together.

Organiser Alex Blackwood, CEO of the International Education Business Partnership Network (IPN) says the inaugural international teacher event has grown out of a long standing Scottish Space School (SSS) involvement with young people and teachers visiting Houston twice a year for the last eight years.

“We decided, through the IPN, to internationalise the teacher event,” Blackwood says. “The aim is to help educators in their approach to teaching science, technology, engineering and maths by involvement with the international space community, and demonstrate the benefits of using space exploration in an educational context for all grades and levels.”

The five-day International Space Exploration Education Development Program includes workshops with NASA personnel involved in curriculum development, real learning activities at the Challenger Center, an evening star gazing at the observatory and a development programme delivered by Space Center Houston’s education team. Included in the US$2300 cost is a tour of Space Center Houston, a private tour of the Johnson Space Center, evening events with astronauts, scientists and engineers from NASA, and access to all of NASA’s curriculum support material.

Applications close in October for the January 2011 session, contact alexblackwood@live.co.uk

Stephen Hawking on the Kerr solution

“In 1963, Roy Kerr, a New Zealander, found a set of solutions of the equations of general relativity that described rotating black holes. These ‘Kerr’ black holes rotate at a constant rate, their size and shape depending only on their mass and rate of rotation. If the rotation is zero, the black hole is perfectly round and the solution is identical to the Schwarzschild solution. If the rotation is non-zero, the black hole bulges outward near its equator (just as the earth or the sun bulge due to their rotation), and the faster it rotates, the more it bulges. So, to extend Israel’s result to include rotating bodies, it was conjectured that any rotating body that collapsed to form a black hole would eventually settle down to a stationary state described by the Kerr solution. In 1970 a colleague and fellow research student of mine at Cambridge, Brandon Carter, took the first step toward proving this conjecture. He showed that, provided a stationary rotating black hole had an axis of symmetry, like a spinning top, its size and shape would depend only on its mass and rate of rotation. Then, in 1971, I proved that any stationary rotating black hole would indeed have such an axis of symmetry. Finally, in 1973, David Robinson at Kings College, London, used Carter’s and my results to show that the conjecture had been correct: such a black hole had indeed to be the Kerr solution.”

From A Brief History of Time (Bantam Books, 1988), chapter 6.