Professor David Crighton

An obituary by J.E. Ffowcs Williams

David Crighton, Master of Jesus College, Cambridge, since 1997 and Professor of Applied Mathematics at Cambridge University since 1986, was probably the most respected head of a Mathematics department in Britain. He was a superb mathematical researcher, an excellent academic administrator and a very good friend.

There was something that sparkled in Crighton's behaviour and the unexpected things about him provided as much fun as the sheer brilliance of his research did satisfaction. The boyish enthusiasm, brilliance and charm evident in my first meeting with him never vanished. If they sometimes left the surface, they were never far beneath. Crighton had a lot of dark wavy hair and he carried a huge, almost spherical crash helmet for commuting on his scooter. It is hard to think why this image of him was so memorable, but it was.

He had turned up one day in the Sixties unexpectedly in my office at Imperial College, London, then temporarily housed in the Victoria and Albert Museum, evading the usually impenetrable shield of museum porters, to tell me that teaching mathematics to large classes of part-time, half-interested night-school students, though highly paid, was not what he was cut out to do. Instead he wanted to research turbulence with me. How he got to be a night-school lecturer from being a first-class undergraduate at Cambridge was a mystery, as was his selection of research subject and supervisor.

Later it was fun to hear him recount our meeting and my reaction to his plan. Nothing useful was known about turbulence, and I believed that the situation was unlikely to change; he would certainly not study the subject with me. Effects caused by turbulence were quite different matters, and it was not long before we had agreed that the effect of bubbles on the noise of underwater turbulence was a much more interesting topic.

The American navy kindly supported the work and dramatic results were soon discovered and published in the Journal of Fluid Mechanics in 1969. It attracted a great deal of attention. The navy reacted to their receipt of a reprint by classifying the work "secret". The paper was plagiarised and produced at a plenary lecture of an important international conference in Eastern Europe. Inevitably the research funds were abruptly cut off.

It was hard to see how it was possible to live a calm life in the tiny house where he and his first wife, Mary, raised their family, every bit of space packed with musical things and every instant bringing new and different interests. Equally striking was the impact he made in the Bedford van that he graduated to when scooter days were over. He stuck for some time to the advice of the van's previous owner who attributed its fine mechanical condition to never allowing the engine to operate outside its range of maximum efficiency; that was a narrow range at very high revs.

At Imperial College, where he had been appointed Research Assistant in 1967, his research became more and more directed at controlling the noise of fast aircraft. Concorde was very noisy, with no one really understanding the noise production process. Industrial leaders backed a mathematically led attack on the problem, organised through the Concorde Noise Panel, of which Crighton was a member from 1965. His outstanding research ability was his credential for membership. Surprisingly he also seemed to know a very great deal about aeroplanes.

Indeed, he was the aviation correspondent of the New Scientist, a fact that came as a surprise to me. Crighton was soon appointed to the Noise Research Committee of the Aeronautical Research Council and became the Committee's chairman. His contribution to the development of a sound mathematical basis for understanding important noise problems was outstanding.

Crighton's papers and written work were beautifully produced. He had good handwriting and rarely seemed to have to go back to make corrections. He had a prodigious work-rate and always appeared to deliver what he had promised. He certainly knew and was confident of his ability, though it did surprise him much more than it surprised his friends when his first real academic job turned out to be the Senior Mathematics Chair at Leeds, which he held from 1974 until 1985.

Crighton was well known internationally, partly because he invariably accepted research challenges and partly because he was willing to accept many invitations to lecture around the world - he even seemed to enjoy long-distance travel cramped into very short periods. He had a great deal of energy. His wife Johanna shared this energy and while travelling with him would sometimes devise diversionary antics to relieve the pressure of heavy lecturing sessions.

The two of them attended a lecture I gave in the United States at Stanford on the subject of aerodynamic drag, and to this day I can't believe that I agreed to their scheme and actually presented the lecture in drag. He had fun exposing me to such hazards, but was wonderfully protective and comforting when friends were attacked. I remember distinctly his assurance that a belligerent questioner had been so fascinated by my finger that he had altogether failed to notice that I was using it to point out something important.

One reason why Crighton made so many professional friends was his willingness to tackle new problems. Because he was very bright he usually made progress. But as important as anything was his kindness to colleagues and his gentle treatment of their often tentative ideas. He seemed to apply his mind to finding the circumstances under which a tentative conjecture would be correct; he rarely made discouraging observations on the limitations of ideas. In this way those who worked with him enjoyed a feeling of joint ownership of results.

Not all of his enthusiasms for the niceties of a subject were shared, or even appreciated by all his colleagues. His studies of long-distance sound propagation led him to become expert on equations engineers consider exotic. He would try to convey an impression of their wonderful properties with elaborate and clever mathematical asides. I recall, while listening to his lecture on solitons (a solitary wave), about which he was very excited and thrilled, wondering whether the tendency for dog owners to take on characteristics of their pets could also be true of mathematicians, and even imagined I observed some soliton qualities in him.

Crighton seemed to get involved in the appointment of most new British professors of Applied Mathematics and was never far away from the centre of schemes devised by government to improve the public understanding of the subject. He was a tireless worker with a very broad range of interests, his main enthusiasm being directed to inspiring the most able graduates. At Cambridge, as head of one of the world's leading departments, with a highly talented student intake, he had plenty of scope and he used it well.

He was brilliant at making it appear that his group was the most able and the most likely to deliver the benefits that funding agencies claimed would follow their initiatives. He was similarly brilliant at instilling confidence in international industrial leaders that really useful knowledge would follow from their investment in research.

He was admired for the way he was able to expand his department while at the same time protecting the standard of scholarship and doing so by leveraging his resources with an effectiveness more often associated with commerce than academia. In recent years his university job had been overwhelmingly administrative, an aspect of life as the subject's top man that appealed less to him than the inspired research that got him there.

The happiest, and by far the most significant, part of his Cambridge period started with his election in 1997 to the Mastership of Jesus, a position that allowed him to spend much more time in personal contact with young, very good students, again. His was a very successful Mastership. The more that was expected of him, the more he liked it, a pleasure shared by Johanna, who enjoyed the college as much as he did.

David Crighton's appearance changed dramatically some 10 years ago after he was attacked outside a hotel in Brussels, and resisted his attackers. They hurt him. He was admitted to hospital, but returned next day to lecture again - an action that worried his friends. Soon after that he lost all his hair and lost it very quickly, so that many of his friends had the experience of not recognising him when they next met. That made him uncomfortable, but he came to terms with it and soon went on to become Master.

It was a tragedy that the happiest period of his life was so suddenly interrupted by cancer, and I found it particularly distressing to see him react to that illness by working even harder than before, rather than enjoying a thoroughly deserved period of relaxation. But his work did not deteriorate as he grew weaker, and that may well have given him more pleasure than any more obviously pleasurable pastime could provide.

J.E. Ffowcs Williams