Jeans, Sir James Hopwood

(1877-1946), mathematician and astronomer

by A. J. Meadows

© Oxford University Press 2004 All rights reserved

Jeans, Sir James Hopwood (1877-1946), mathematician and astronomer, was born on 11 September 1877 at 29 Kew Road, Birkdale, Lancashire, the only son of William Tulloch Jeans, parliamentary journalist, and his wife, Martha Ann Hopwood. On his father's side there was a strong newspaper tradition: both his grandfather and his great-grandfather had owned newspapers. His mother came from a strongly evangelical family, and this made for a rather strict and unhappy childhood. However, he shared a liking for walking with his father, and the latter, who wrote two popular science books, encouraged his son's intellectual interests.

Jeans was numerate from an early age. He could tell the time at the age of three, and enjoyed memorizing strings of numbers. His greatest enthusiasm was reserved for clocks. From early on he took pleasure in drawing them and in working out how they operated. When he was three years old his family moved to Tulse Hill, London. From 1890 he attended the nearby Merchant Taylors' School. His mathematical abilities rapidly became evident, and he also developed his skill in playing the piano and the organ. In 1896 he went up to Trinity College, Cambridge, as a scholar to read mathematics. He and his fellow undergraduate, G. H. Hardy, were advised to take part one of the tripos in two years rather than the normal three. He thrived on the challenge, and in 1898 was bracketed second wrangler. His work for part two was interrupted by tuberculosis of the knees and wrists, which required him to spend considerable time in two sanatoriums. He was not finally cured until 1903. Despite this he was awarded a first class in part two in 1900, followed by an Isaac Newton studentship and a Smith's prize. In 1901 he was elected a fellow of his college, and in 1904 was appointed a university lecturer in mathematics.

During his stay in the sanatoriums Jeans extended the interest in molecular motions that he had demonstrated in his Smith's prize essay. He published the result in 1904 as the Dynamical Theory of Gases. This reigned for many years as a standard textbook on the topic, and was rewritten and republished in 1940 as An Introduction to the Kinetic Theory of Gases. Jeans's prime concern in his Smith's prize essay had been the equipartition of energy in a dynamical system of interacting bodies. From an examination of matter alone, he then went on to consider a system containing both matter and radiation. In 1905 he published a correction to a solution given by Lord Rayleigh for the wavelength distribution of black body radiation. The resulting Rayleigh-Jeans law indicated that at equilibrium almost all energy would radiate at short wavelengths. This was contradicted by Max Planck's empirically successful model, which posited energy quantization, violating the rules of classical thermodynamics. To save classical principles Jeans argued that the observed Planck distribution might be a steady state which slowly gave way to his predicted short wavelength pattern.

In the autumn of 1904 Jeans applied for the vacant chair of mathematics at the University of Aberdeen. He was not appointed but in the following summer, while attending a meeting of the British Association in Cape Town, he received the offer of a chair in applied mathematics from the president of Princeton University, Woodrow Wilson. He stayed at Princeton for only four years, but it proved to be a busy time of his life. In 1906 he was elected a fellow of the Royal Society at the early age of twenty-eight. In 1907 he married Charlotte Tiffany Mitchell, daughter of Alfred Mitchell, explorer, of New London, Connecticut, and related to the well-known Tiffany family of New York. During his stay in the United States he also published two successful textbooks: Theoretical Mechanics (1906) and Mathematical Theory of Electricity and Magnetism (1908).

Jeans returned to England in 1909 and in the following year was appointed Stokes lecturer in applied mathematics at Cambridge University. In 1912 he retired from this post in order to devote his entire time to research and writing. His wife was well-to-do (and, in due course, he obtained considerable income from his popular works). In 1914 he produced a Report on Radiation and the Quantum Theory for the Physical Society of London, which, unlike his 1905 work, denied that classical principles could even transiently allow the Planck distribution of black body radiation, thus underlining the radical contrast with the new quantum approach. However, astronomy was now becoming the main focus of his interest. In 1917 he gave the Bakerian lecture to the Royal Society on 'The configurations of rotating compressible masses', and in the same year was awarded the Adams prize of the University of Cambridge for an essay on 'Problems of cosmogony and stellar dynamics', published as a book in 1919. Both these texts dealt with the shapes taken up by rotating, gravitating bodies: a problem of fundamental importance that had already been tackled by some of the leading mathematicians, including Jeans's former colleague at Cambridge, Sir George Darwin. As the title of his Adams prize essay indicates, Jeans had long been interested in stellar motions, as well as rotations. Here his concern with the microscopic and macroscopic came together, as the theory developed for molecules in a gas was applied to collections of stars.

In June 1917 Jeans started a long dispute on stellar structure with the professor of astronomy at Cambridge, Arthur Eddington. Jeans attacked Eddington's model of internal radiative equilibrium and, on the basis of the high degree of ionization within stars, queried the link between star mass and luminosity. In early 1918 at the Royal Astronomical Society, the forum for their increasingly tetchy debates, Jeans countered Eddington's pulsation model for cepheid variable stars with a theory of periodic explosions. The arguments between the two on this and other matters went on for some years, and became sufficiently famous that some joined the Royal Astronomical Society primarily in order to listen to their debates. During the early 1920s Jeans judged gravitational condensation the only energy source in stars; then after Eddington's 1924 account of radioactive annihilation, Jeans conceded that this might also be an energy source and applied it to idiosyncratic accounts of liquid stellar cores. He summarized this research in Astronomy and Cosmogony (1928), his swansong in original investigations.

In 1919 Jeans was awarded a royal medal of the Royal Society and elected an honorary secretary of the society. His major achievement during his period of office was to enhance the prestige of the Proceedings of the Royal Society A (which published research in the physical sciences). Prior to his time most of the important papers in physics had appeared elsewhere: from now on, the Proceedings became an important source of new research information. The decade of the 1920s brought him a range of other honours. In 1922 he was awarded the gold medal of the Royal Astronomical Society. He subsequently became president (1925-7), presenting it in 1926 with £1000 for an annual lecture--called the George Darwin lecture--to be given by an overseas scientist. He won the Hopkins prize of the Cambridge Philosophical Society for 1921-4; the citation mentioned his work on the theory of gases, on radiation, and on the evolution of stellar systems. He gave the Halley lecture at Oxford in 1922, the Guthrie lecture of the Physical Society of London in 1923, and the Rouse Ball lecture at Cambridge in 1925. He was knighted in 1928 for his services to science, including those to the Royal Society (where he ceased to be secretary in the following year).

In 1928 Jeans's Astronomy and Cosmogony came to the attention of S. C. Roberts, the secretary of Cambridge University Press, who appreciated the general interest of its subject matter and the attraction of Jeans's writing style. He persuaded Jeans to write a popular account, The Universe around Us, which was published by the press in 1929. One stimulus for Jeans had been the success of Eddington's attempt at this kind of writing in the previous year. The success of his own publication led to a series of popular books during the remainder of his life; these took precedence over original research. His popularity as a writer depended partly on his topic--new, thought provoking views of the universe--and partly on his style, which combined an authoritative knowledge of the subject with a vivid turn of phrase. In 1930 he gave the Rede lecture at Cambridge. An expanded version was published simultaneously as The Mysterious Universe. His conclusion has often been quoted: 'the Great Architect of the Universe now begins to appear as a pure mathematician'. One result of these books was that he came to be in great demand as a lecturer and broadcaster.

Ever since his days at Princeton Jeans had maintained close contacts with colleagues in the United States, especially with G. E. Hale, the founder of the Mount Wilson observatory in California. In 1923 he was accorded the rare honour of being appointed a research associate of the observatory, which encouraged further visits to the USA. In 1931 he was awarded the Franklin medal of the Franklin Institute in Philadelphia. He also became a foreign member of the National Academy of Sciences in Washington. In the 1930s Jeans also visited India, taking over the presidency of the jubilee meeting of the Indian Science Congress when Lord Rutherford died. He was awarded the Mukerjee medal in 1937 followed by the Calcutta medal in 1938.

At home Jeans received a succession of new honours. In 1934 he became president of the British Association for its meeting in Aberdeen, taking over unexpectedly when the president-elect, Sir William Hardy, died suddenly. In the following year the Royal Institution decided to establish a professorship of astronomy. Jeans, who had given the institution's Christmas lectures in 1933, was invited to fill the post. He held it until shortly before his death. Jeans was vice-president of the Royal Society in 1938-40, and in 1941 was made an honorary fellow of his old college at Cambridge. The Merchant Taylors' Company admitted him to its honorary freedom, and he was the recipient of honorary degrees from many universities: Aberdeen, Benares, Calcutta, Dublin, Johns Hopkins, Manchester, Oxford, and St Andrews. He received the ultimate accolade of the Order of Merit in 1939.

Music remained one of Jeans's great interests throughout his life. When he moved to Cleveland Lodge, Dorking, in 1918, he installed an organ and often played on it for hours at a time. His wife died in 1934 after an extended illness. The following year he met Susanne (Susi) [see Jeans, Susanne (1911-1993)], daughter of Oskar and Jekaterina Hock of Vienna. She was already, at the age of twenty-four, an internationally recognized organist. The two were married in Vienna on 30 September 1935 after a week's engagement. Jeans installed a second organ at Cleveland Lodge for his wife's use. The two separate organ rooms were well insulated for sound, so that Jeans and his wife could practise whenever they wished without disturbing each other. Jeans became a director of the Royal Academy of Music in 1937, and the following year, at his wife's instigation, published a semi-popular book, Science and Music.

In terms of personality Jeans tended to hold himself aloof, and could be both supercilious and sarcastic. However, those who knew him best believed a significant factor in this was his innate shyness. This may also have been reflected in his extreme unwillingness to play the organ in front of others. At the same time he was hard-working and businesslike with excellent lecturing abilities. Both during his lifetime and since it has been felt that, though an outstanding mathematician, he sometimes lacked a physical feel for the situations he was trying to describe mathematically. In this respect he has been seen as less successful than his contemporary, Eddington. To some extent, this is unfair: not only has some of Jeans's work had an important impact on astronomy, but, in addition, Eddington--as Jeans thought--was not always right. Nevertheless, more recent re-evaluation of Jeans's contributions has tended still to emphasize the value of the mathematical formulation, rather than the physical insight.

During the First World War Jeans lived at various addresses in Sussex and Surrey. In the Second World War, Cleveland Lodge, his Surrey home, was requisitioned by the military, so the family moved to Somerset. Jeans had a heart problem in 1917, but seemed to have fully recovered in the inter-war years. Illness struck again in Somerset, and early in 1945 he experienced a coronary thrombosis. Again he seemed to make a good recovery, but a second attack followed in the autumn. On 16 September 1946, not long after his post-war return to Cleveland Lodge, Jeans died. He was buried in the churchyard at nearby Mickleham, Surrey. He was survived by his second wife, one daughter from his first marriage, and two sons and one daughter from his second marriage.


E. A. Milne, Sir James Jeans (1952)
E. A. Milne, Monthly Notices of the Royal Astronomical Society, 107 (1947), 46-53
E. A. Milne, Obits. FRS, 5 (1945-8), 573-89
election certificate, RS
b. cert.

RS, corresp. and papers |  BL, corresp. of him and his wife with Marie Stopes, Add. MS 58543
California Institute of Technology, Pasadena, archives; corresp. with George Hale
Nuffield Oxf., corresp. with Lord Cherwell
Ransom HRC, letters to Sir Owen Richardson

W. Stoneman, photograph, 1922, NPG
P. A. de Laszlo, photograph, 1924, RS [see illus.]
H. Coster, photographs, 1930-39, NPG
P. A. de Laszlo, portrait, priv. coll.
photograph, RAS
three photographs, RS

Wealth at death  
£256,054 9s. 1d.: probate, 11 Dec 1946, CGPLA Eng. & Wales

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