Sydney Chapman (mathematician)

For other people named Sydney Chapman, see Sydney Chapman (disambiguation).

Professor Sydney Chapman
Sydney Chapman 1888 – 1970
Born	(1888-01-29)29 January 1888 Eccles
Died	Boulder, Colorado
Institutions	University of Manchester University of Cambridge University of Oxford The Queen's College, Oxford Royal Observatory, Greenwich
Alma mater	University of Manchester Trinity College, Cambridge
Academic advisors	G. H. Hardy
Doctoral students	Franz Kahn George Temple Syun-Ichi Akasofu
Known for	Chapman function Chapman–Kolmogorov equation Chapman–Enskog theory
Notable awards	Fellow of the Royal Society (1919) Smith's Prize (1913) Adams Prize (1928) Royal Medal (1934) The Chree Medal and Prize (1941) De Morgan Medal (1944) William Bowie Medal (1962) Copley Medal (1964) Symons Gold Medal (1965)

Sydney Chapman FRS (29 January 1888 – 16 June 1970) was a British mathematician and geophysicist. His work on the kinetic theory of gases, solar-terrestrial physics, and the Earth's ozone layer has inspired a broad range of research over many decades.

Biography

Chapman was born in Eccles, near Salford in England and began his advanced studies at a technical institute, now the University of Salford, in 1902. In 1904 at age 16, Chapman entered the University of Manchester. He competed for a scholarship to the university offered by his home county, and was the last student selected. Chapman later reflected, "I sometimes wonder what would have happened if I'd hit one place lower." He initially studied engineering in the department headed by Osborne Reynolds. Chapman was taught mathematics by Horace Lamb, the Beyer professor of mathematics, and J.E. Littlewood, who came from Cambridge in Chapman's final year at Manchester. Although he graduated with an engineering degree, Chapman had become so enthusiastic for mathematics that he stayed for one further year to take a mathematics degree. Following Lamb's suggestion, Chapman applied for a scholarship to Trinity College, Cambridge. He was at first awarded only a partial scholarship as a sizar (meaning that he obtained financial support by acting as a servant other students), but from his second year onwards he received a full scholarship. He graduated as a wrangler in 1910. He began his research in pure mathematics under G. H. Hardy, but later that year was asked by Sir Frank Dyson to be his chief assistant at the Royal Greenwich Observatory. From 1914 to 1919 he returned to Cambridge as a lecturer in mathematics and a fellow of Trinity. He held the Beyer Chair of Applied Mathematics at Manchester from 1919 to 1924, the same position as had been held by Lamb, and then moved to Imperial College London. During the Second World War he was Deputy Scientific Advisor to the Army Council.

In 1946, Chapman was elected to the Sedleian Chair of Natural Philosophy at Oxford, and was appointed fellow of The Queen's College, Oxford. In 1953, on his retirement from Oxford, Chapman took research and teaching opportunities all over the world, including at the University of Alaska and the University of Colorado, but also as far afield as Istanbul, Cairo, Prague, and Tokyo. As the Advisory Scientific Director of the University of Alaska Geophysical Institute from 1951 to 1970, he spent three months of the year in Alaska, usually during winter for research into aurora. Much of the remainder of the year he spent at the High Altitude Observatory in Boulder, Colorado.

The relationship of Chapman with some German geophysicists (e.g. Ertel, Bartels, and A. Schmidt) has been investigated by Wilfried Schröder.

In 1970, Chapman died in Boulder, Colorado at the age of 82.

Work

Chapman's most noted mathematical accomplishments were in the field of stochastic processes (random processes), especially Markov processes. In his study of Markovian stochastic processes and their generalisations, Chapman and the Russian Andrey Kolmogorov independently developed the pivotal set of equations in the field, the Chapman–Kolmogorov equations. Chapman is credited with working out, in 1930, the photochemical mechanisms that give rise to the ozone layer.

Chapman is also recognised as one of the pioneers of solar-terrestrial physics. This interest stemmed from his early work on the kinetic theory of gases. Chapman studied magnetic storms and aurorae, developing theories to explain their relation to the interaction of the Earth's magnetic field with the solar wind. He disputed and ridiculed the work of Kristian Birkeland and Hannes Alfven, later adopting Birkeland's theories as his own. Chapman and his first graduate student, V. C. A. Ferraro, predicted the presence of the magnetosphere in the early 1930s. They also predicted characteristics of the magnetosphere that were confirmed 30 years later by the Explorer 12 satellite.

In 1940 Chapman and a German colleague Julius Bartels at the Carnegie Institution of Washington published a book in two volumes on geomagnetism, which was to become the standard text book for the next two decades.

Chapman was President of the Special Committee for the International Geophysical Year (IGY). The idea of the IGY stemmed from a discussion in 1950 between Chapman and scientists including James Van Allen. The IGY was held in 1957–58, and resulted in great progress in fields including Earth and space sciences, as well as leading to the first satellite launches. Chapman's role in the IGY and his support for amateur's work in auroras and noctilucent clouds, especially also with the Germans, has been discussed by Wilfried Schröder.

Honours

Chapman was bestowed many honours over his career including Smith's Prize in 1913, election as a Fellow of the Royal Society in 1919, Royal Society Bakerian lecturer in 1931, Royal Society Royal Medal in 1934, London Mathematical Society De Morgan Medal in 1944. In 1949, he was awarded the Gold Medal of the Royal Astronomical Society and was elected as a Fellow of the Royal Society of Edinburgh in 1953. In 1964, he was awarded the Copley Medal of the Royal Society. He was elected to the National Academies of Science of the United States, Norway, Sweden and Finland. He served as President of the London Mathematical Society during 1929–1931 and the Royal Meteorological Society 1932–1933.

The lunar Crater Chapman is named in his honour, as is the Sydney Chapman Building on the campus of the University of Alaska Fairbanks. This building served as the first permanent home of the University of Alaska Geophysical Institute, and it now contains the Department of Computer Science and the Department of Mathematics and Statistics. The American Geophysical Union organises "Chapman Conferences," which are small, topical meetings intended to foster innovative research in key areas. The Royal Astronomical Society founded the Chapman Medal in his memory.

External links

• Finding aid to papers of Sydney Chapman, Niels Bohr Library and Archives, accessed 7 September 2008
• Sydney Chapman page at the Geophysical Institute of the University of Alaska, Fairbanks includes sections from Sydney Chapman, Eighty, From His Friends, accessed 4 October 2008

Preceded by Horace Lamb

Beyer Chair of Applied Mathematics at University of Manchester 1924–1928

Succeeded by Edward Arthur Milne