Spotlight

A Mathematical Life

By Jeff Field

Open any book dealing with black holes and you'll see the Kerr Solution mentioned, a celebrated solution of Einstein's relativity theory equations named for New Zealand mathematician Roy Kerr.

Professor Kerr was just 29 years old when he published the solution which won him international accolades and a place in science history. Some 30 years later he is retiring from academic life at the University of Canterbury.

"After that [the Kerr Solution], a lot of things I have done seem small bikkies. There has been other work I have done of significance, but I sometimes think I might have achieved more if I had done less at the beginning," Kerr says.

His solution has had a profound effect on theoretical physics. Professor Subrahmanyan Chandrasekhar, an eminent US astrophysicist, said that the most shattering moment in his life was the realisation that Kerr's discovery provided the exact representation of untold numbers of black holes throughout the universe.

Kerr's mathematical skills were evident early on, and his first year as a student at Canterbury saw him sit in on Stage III lectures. However, he was bound by the regulations of the time which required three years to be spent on a BSc.

"I took the Masters lectures in my second year...but it was a further two years before I could sit," he says. "It was a bit stupid, but I got to play a lot of billiards."

Kerr graduated MSc with first class honours in 1954 and went to Cambridge University on scholarship.

"In those days, if you were going overseas to do maths, it was just assumed you would go to Cambridge. There was still the attitude in New Zealand that American universities were second-rate and the best students came from Cambridge and Oxford -- which was complete rubbish."

From Cambridge, Kerr went to the United States, doing postdoctoral work at Syracuse University and the University of Texas at Austin. During his first year at the latter, he did the work that culminated in the Kerr Solution in 1963.

Researchers had long been interested in the solutions to the gravitational equations representing a rotating body. It had been found that it was possible for a non-rotating star to collapse until it was so dense that not even light could escape its surface, but it was conjectured that if the star was rotating even slightly then it would never collapse completely.

The head of Kerr's group, Professor Schild, was very interested in the rotating issue and knew the significance of Kerr's find.

"One day he came into my office and sat there smoking his pipe while I calculated [the star's] rotation. It took about half an hour and, sure enough, it was spinning. He was wildly excited. I didn't realise at the time how important it was going to be, but he did. It was then published and it has turned out over the years that it has been essential for people who study black holes and rotating bodies."

In 1971, Kerr returned to New Zealand to take up the position of Professor of Mathematics at the University of Canterbury. He has always been keen to emphasise the research role of mathematics, but recognises the problems that professional mathematicians have.

"Most people who are talented in mathematics would be better off in the end to do something else career-wise. It is not easy to do research in mathematics, and there are many applied areas where they can apply their mathematical talents," he warns.

This mathematician once considered life as a professional bridge player. Now, as Emeritus Professor, he's looking forward to sailing off to a conference in Tonga on a Cavalier 45 yacht.

Jeff Field is Information Officer at the University of Canterbury.

Jeff Field is Information Officer at the University of Canterbury.