1 SIR JAMES LIGHTHILL AND HIS CONTRIBUTIONS TO SCIENCE Malcolm J. Crocker Mechanical Engineering Department Auburn University Auburn, AL 36849, USA ABSTRACT Michael James Lighthill born in 1924 is considered by many of his contemporaries to be one of the greatest applied mathematicians and fluid dynamicists of the twentieth century. His papers on jet noise theory written in the 1950s were the first on this topic and have become famous and are referenced extensively. He also did much important original work in many other areas including shock wave theory, biofluiddynamics, wave mechanics, oceanography, atmospheric dynamics, tropical cyclones, typhoons and hurricanes, and magnetohydrodynamics which has been partly overshadowed by his jet noise papers. In addition to his scientific achievements he held several important administrative posts, although at the same time continuing his scientific work. He was knighted in 1971 as Sir James Lighthill. This paper begins with some biographical details and continues with discussions of his major scientific contributions and some of his administrative achievements made during his career. Also some information about his interests in music and swimming is given in order to try to present a balanced picture of him as a person. INTRODUCTION Those of us who are members of the International Institute of Acoustics and Vibration (IIAV) will know Sir James Lighthill as the charter IIAV President from the foundation of IIAV in 1995 and its first elected President after December 1997. Many will have heard his presidential lectures in 1996 and 1997. Most of us will be aware of his seminal work in aerodynamic noise theory and his famous velocity to the eighth power law. But many may not know about his earlier scientific achievements and his other contributions in so many different scientific areas. It is the purpose of this paper to present some less well known aspects of his life and scientific accomplishments. I will begin this paper, 1 2 however, with a few general introductory comments about his career and his scientific approach to problems. Michael James Lighthill was born in January 1924 in Paris. He attended Winchester College and at the age of only 15 was admitted to Cambridge University although he did not attend until he was 17. In 1943 he became involved in supersonic aerodynamics as part of the war effort. In 1946 after a brief period back at Cambridge he went to Manchester University where he was promoted in 1950 to Professor. In 1959 at the age of only 35 he became Director of the Royal Aircraft Establishment (RAE) at Farnborough. In 1965 he became the Royal Society Research Professor at Imperial College London and then in 1969 he went to Cambridge University as the Lucasian Professor. His last post was as Provost of University College London as which he served from 1979 to 1989. He regarded every obstacle whether it was a mathematical or physical problem, learning a foreign language or piece of piano music, or attempting one of his famous “adventure swims” as simply a challenge to be overcome by his scientific intellect, physical endurance and strength. His scientific papers are characterized by their lucidity and by the interdisciplinary perspective with which he views the physics of the problem under consideration. In his papers, Lighthill would normally study a physical problem breaking it into a number of clearly defined sub-problems, which he would approach with powerful mathematical tools. And if the mathematical tools did not exist he would invent his own. His books: “Introduction to Fourier Analysis”, Cambridge, 1958 and “Higher Approximation in Aerodynamic Theory”, Princeton, 1960 are early illustrations of his brilliance in these areas. Sir James was also an able and energetic administrator as Director of the Royal Aircraft Establishment, Farnborough, 1959-1964 and Provost of University College, London, 1979-1989. Nor did his retirement in 1989 put a stop to his scientific enquiries and publications, which he continued extensively to the end. His scientific activities and achievements are very much linked to his academic and administrative positions during his career. Lighthill wrote a large number of mathematical papers and books, and achieved so much in his career, that it is difficult to know how to write about his many achievements. Although I could have included sections on his contributions in different specific areas, I decided in the end to approach this paper in a chronological way. Thus I have mainly divided the paper into different periods of his life together with some general discussions of his scientific contributions made during those periods. I have also included some other sections concerning his swimming and other activities. Of course a mere listing of his achievements can never really describe Sir James adequately. During the last few years when I came to know him quite well, my impression of him was of a person of boundless enthusiasm and curiosity about the 2 3 physical world. Like the high-speed, high-altitude Concorde whose design problems he studied at RAE when he was director, his brain operated at a much higher speed and higher level or altitude than those of most of us mere ‘mortals.’ His scientific work was characterized by his approach of studying each chosen topic in depth so that he could know it better than even the experts and become very confident of his knowledge of the area. He also strongly believed that scientific research was of no real value unless it was shared with others in the scientific community. He was thus very interested to write up and publish all of his scientific work. His writing is characterized by its clarity. It always starts with a concise formulation of the problem, next the theoretical analysis and comparison with experiment or observation of the physical world, and then finally the conclusions. There have been various obituaries and/or articles written about Sir James and his scientific contributions.[1-7] Some were written very soon after his death and are brief and some have minor inaccuracies. The obituary written by David Crighton, however, is extensive and very useful.[1] EARLY YEARS AND THE LIGHTHILL NAME Lighthill’s paternal grandfather, Christian Adolf Lichtenberg was born in Denmark in 1841. His maternal grandfather was a Yorkshire engineer named L. W. Holmes. The Lichtenberg family traced its origin back to Alsace. At the age of 21, Christian Lichtenberg emigrated to Liverpool, England in 1861. He began working for a beef importing company. He married the owner’s daughter and moved to a senior position in the company and ultimately he became its manager. Several children were born and one of their children, Ernst Balzar Lichtenberg, became a mining engineer in England. Ernst found it difficult to get an engineering job in England during the First World War because of his German-sounding family name and the intense anti-German feeling at the time. Thus he decided to change his name from Lichtenberg to Lighthill and made the necessary announcement in the Times newspaper.[8,9] He took his family to France soon after the 1914-18 war ended, first managing a quarry in the Creuse area of France and then moving to Paris. Michael James Lighthill was born on 23 January 1924 in the rue Michel-Ange, Auteuil in Paris. He was the youngest of the three children. He had an elder brother Olaf, and an elder sister, Patricia. Figure 1 shows the young James at 18 months while he was still living in France. 3 4 Fig. 1 James Lighthill at the age of 18 months purposely going to the golf course. The Lighthill family moved back to England in 1927 and settled in North London living in a flat at the bottom of Highgate West Hill. James first attended Byron House, Highgate, a pre-preparatory school for children up to the age of 11, and was escorted there each day by his elder sister Patricia. According to Pat, his mathematical gifts were evident from the start. “When we first arrived at Highgate and before (James) started school, he amazed the local butcher by measuring every surface in the shop and writing the figures down in a little notebook.”[8] Much of James’ early education, in fact, came directly from his father. For his fourth birthday his father gave him an unusual gift for his age. As James was to say later: “Throughout my life I’ve extensively used the superb 11th Edition (1910) of the Encyclopedia Britannica, which I received as a 4th birthday present in 1928....” [9], and “My father had already retired at the earliest date I can remember, and gave me the best part of my education from three to eight, although I also attended kindergarten school. I learnt from him unusual amounts (for my age) of arithmetic, algebra and geometry, geology, astronomy and paleontology. When I was seven, an intelligence test established my mental age as fourteen, but I am sure that this was in great measure due to my father’s instruction in so many things.” [9] James was thus quite a precocious child and usually was allowed to study at school along with children much older than himself.[10] When James was eight he became a boarder at Boxgrove School near Guildford. Figure 2 shows the young James at the age of eight. He was taught mathematics well at Boxgrove by Mr. Coombes and on the strength of his mathematical knowledge at the age of 12 he was placed seventh in the entrance examination to Winchester College winning a scholarship.[9] 4 5 Fig. 2 James at Boxgrove School WINCHESTER COLLEGE When James Lighthill went to his high school, Winchester College, in 1936, as a scholar, he lived in the College (i.e.