Background

James Hopwood Jeans was born on September 11, 1811, in Ormskirk, Lancashire, England. He was the son of William Tullock Jeans, a parliamentary journalist who wrote two books of lives of scientists, and Martha Ann Hopwood. The family moved to London when Jeans was three. He was brought up in a strict, very religious Victorian home atmosphere; his childhood was not very happy and played an important role in forming his personality.

Jeans was a precocious child. His early passion was clocks, which he would dismantle, boil, and reassemble; he wrote a little booklet on clocks at the age of nine.

Education

Jeans attended the Merchant Taylors' School from 1890 to 1896, and entered Trinity College, Cambridge, in 1896; he was the second wrangler on the mathematical tripos in 1898. While recovering from an infection, Jeans took the first class on part two of the tripos in 1900 and was awarded a Smith’s Prize. In the following year, he was elected a fellow of Trinity College, and he obtained his Master of Arts degree in 1903.

Career

Jeans' first treatise, Dynamical Theory of Gases, was published in 1904. It became a standard textbook, both because of its clarity and elegance and because Jeans incorporated into it the results of his own research. From 1905 to 1909 Jeans was a professor of applied mathematics at Princeton University, where he wrote two textbooks, Theoretical Mechanics (1906) and Mathematical Theory of Electricity and Magnetism (1908). The latter work, written in Jeans’s fluent style, was widely used and went through many editions.

Jeans was Stokes lecturer in applied mathematics at Cambridge from 1910 to 1912, when he retired from university duties, devoting himself to research and writing. His Report on Radiation and the Quantum Theory appeared in 1914 and helped to spread acceptance of the early quantum theory. From this time his interest turned more exclusively to astronomy, culminating in his Adams Prize essay, Problems of Cosmogony and Stellar Dynamics (1919), and his book Astronomy and Cosmogony (1928). In 1923 he was made a research associate of the Mt. Wilson Observatory; from its establishment in 1935 until the year of his death he held the chair of astronomy of the Royal Institution.

Jeans’s biographer E.A. Milne, divided his scientific life into four parts. During the first of these, from the taking of his degree to 1914, Jeans devoted his major attention to problems of molecular physics. After an initial student work, with the assistance of J. J. Thomson, on electrical discharges in gases, he turned to the foundations of kinetic molecular theory. In his attempt to provide a new derivation of the theorems of kinetic theory avoiding the assumption of “molecular disorder,” he was challenged by S. H. Burbury, with whom he carried on a controversy. His first book, The Dynamical Theory of Gases, includes his treatment of the persistence of molecular velocities after collisions. When a molecule undergoes a collision in gas there is, statistically, a tendency for it to maintain some motion in the direction that it took before the collision. If account is taken of this favoring of forward motion over rebounding, correction factors must be included in the derivation of the coefficients of viscosity, heat conduction, and diffusion of gases. His major efforts, though, were devoted to the problems posed by the classical theorem of equipartition of energy in its application to specific heats and particularly to blackbody radiation.

In 1905, Jeans corrected a numerical error in Rayleigh’s derivation of the classical distribution of blackbody radiation, so that the law has become known as the Rayleigh-Jeans law. This law states that if a hot body is placed inside a reflecting cavity, nearly all the heat energy will be associated with high-frequency radiation in the cavity when equilibrium is reached, the body cooling off and approaching absolute zero in temperature. But the facts, which were well presented by Planck’s law, showed a reasonable distribution of energy between matter and radiation, with the highest concentrations of radiant energy associated with a finite frequency and relatively little of such energy concentrated in the high frequencies.

As early as 1902-1903 Jeans had occupied himself with the forms and stability of rotating liquid masses, inspired in this by the work of George Darwin. Poincaré had traced the evolution of a rotating incompressible fluid mass slowly contracting gravitationally through ellipsoidal figures to a pearshaped figure but was unable to decide the stability of the latter. By an incomplete argument Darwin concluded that the pear-shaped figure was stable, but in 1905 Lyapunov demonstrated the opposite. Jeans’s earliest work in this field had been to compute the equilibrium figures of rotating liquid cylinders; this simplified problem allowed him to refine the calculations to a much higher degree of accuracy while still showing characteristics of the more complex three-dimensional case. He returned to the general problem in papers published in 1914-1916, demonstrating that Darwin had not gone to a sufficiently high approximation in his calculations to be able to decide the stability of the pear-shaped figure and that, if this were done, the figure was indeed shown to be unstable.

His masterful work on the equilibrium of rotating masses, culminating in the Adams Prize essay, constitutes the second phase of Jeans’s career. After this, he continued to work on astrophysical problems for another decade, until 1928. In connection with his work on rotating stars, he introduced in 1926 the concept of radiative viscosity and computed its coefficient. Much of this work on stellar interiors, based on assumptions which could not then be tested, has not held up with the passage of time. Jeans’s astrophysical investigations were gathered together in Astronomy and Cosmogony (1928), which was practically his last research work.

From 1928, Jeans occupied himself with the popularization of science. In that year he gave a series of radio lectures which served as a source for The Universe Around Us (1929). By impressive analogies, Jeans conveyed to his readers some idea of the immense differences in scale from the atomic nucleus to the galaxies, then proceeded to sketch his ideas concerning the evolution of stars and the universe. The Rede lecture in 1930 led to The Mysterious Universe, in which, after a discussion of modern physics and astronomy, he propounded his rather uncritical idealistic speculations, picturing the universe as “the thought of a mathematical thinker.” The book was immensely popular and appeared in at least fourteen languages. Further works followed: The Stars in Their Courses and Through Space and Time, popularizing astronomy, and The New Background of Science, treating modern physics, all written in Jeans’s fluent and exciting style. His final books, Physics and Philosophy (1942) and The Growth of Physical Science (1947), were written in a more historical and restrained manner.

Achievements

• 

  Famous equally as a mathematician, as a theoretical physicist, an astronomer, and expositor of all three sciences, James Hopwood Jeans played a major role in applying quantum theory to astrophysics and developing sophisticated mathematical models of the behavior of gases in condensed states. One of Jeans' major discoveries, named Jeans length, is a critical radius of an interstellar cloud in space. He came up with another version of this equation, called Jeans mass or Jeans instability, that solves for the critical mass a cloud must attain before being able to collapse. He is also credited with calculating the rate of atmospheric escape from a planet due to kinetic energy of the gas molecules, a process known as Jeans Escape. Two of his books, The Universe around Us and The Mysterious Universe became best-sellers.
  
  He was knighted in 1928. Other honors included the Royal Medal of the Royal Society (1919), the Hopkins Prize of the Cambridge Philosophical Society (for 1921-1924), the gold medal of the Royal Astronomical Society (1922), and the Franklin Medal of the Franklin Institute (1931).
  
  The crater Jeans on the Moon is named after him, as is the crater Jeans on Mars.
  
  The String Quartet No.7 by Robert Simpson was written in tribute to him on the centenary of his birth, 1977.
  
  At Merchant Taylors' School there is a James Jeans Academic Scholarship for the candidate in the entrance exams who displays outstanding results across the spectrum of subjects, notably in mathematics and the sciences.

Works

More photos

• book

  • The Mathematical Theory of Electricity and Magnetism 1908
  • Physics and Philosophy 1942
  • The Dynamical Theory of Gases 1925
  • The Mysterious Universe 1944
  • Astronomy and Cosmogony 1928
  • An Introduction to the Kinetic Theory of Gases 1940
  • Science and Music 1937
  • Growth of Physical Science 1951
  • The motion of tidally-distorted masses 1917
  • The new background of science 1934
  • Through space and time 1949
  • Eos, or, The wider aspects of cosmogony 1928
  • On the instability of the pear-shaped figure of equilibrium of a rotating mass of liquid 1918
  • Report on Radiation and the Quantum-Theory 1924
  • The New Background of Science 1933
  • Problems of Cosmogony and Stellar Dynamics 1919
  • The Stars in Their Courses 1931
  • Atomicity and quanta 1926
  • On the Vibrations and Stability of a Gravitating Planet 1903

Religion

Jeans was brought up in a very religious Christian family, amongst much formal religious observance.

Views

In 1905 Jeans hoped to preserve classical physical ideas, according to which the Rayleigh-Jeans law represented the true ultimate equilibrium distribution, by arguing that such a distribution would not be reached for an extremely long time under most conditions, because the usual processes generating radiation (such as collisions involving charged bodies) would produce very little high-frequency radiation at low or moderate temperatures. Jeans held that a steady-state distribution of radiant energy would quickly set in, which would not be the true equilibrium distribution because energy would be dissipated into the high frequencies at a very slow rate. He believed that Planck’s law represented such a steady-state distribution.

In 1914, when Jeans presented his Report on Radiation and the Quantum Theory to the Physical Society, he had abandoned these ideas. This report was strongly influenced by Poincare’s important memoir of 1912, Sur la théorie des quanta, which demonstrated the near-impossibility of circumventing the quantum hypothesis by classical arguments. Jeans constructed arguments convincing himself that Planck’s law could not result as a steady-state distribution in classical physics; and in this report, he stressed as sharply as possible the break which the early quantum theory represented with classical principles and the inadequate state of the quantum theory of that time. Yet he did not contribute to the development of this theory, turning at this time almost exclusively to astrophysics.

Jeans went beyond his predecessors by treating compressible as well as incompressible fluids. His results, summarized in his Adams Prize essay, Problems of Cosmogony and Stellar Dynamics (1919), led him to distinguish two cases, represented in their extremes, respectively, by an incompressible mass of fluid and by a gas of negligible mass surrounding a mass concentrated at its center (Roche’s model).

Fluid masses with properties intermediate between the incompressible fluid and Roche’s model behaved in either of these two ways, with the conditions for fissional or equatorial breakup well specified. As a result, Jeans concluded that rotation of a contracting mass evidently could not give rise to the formation of a planetary system. For this reason, he rejected the theory of the origin of the solar system of Kant and Laplace and favored a tidal theory somewhat like that of T. C. Chamberlin and F. R. Moulton, in which planetary systems were created during the close passage of two stars. Jeans had developed a formula giving the approximate distance between gravitational condensations in a gaseous medium, which he had applied to the matter in the arms of spiral nebulae.

From 1913 he applied kinetic theory arguments to the stars making up a star cluster or a galaxy. An association of stars should approach a Maxwellian distribution of velocities over a very long period of time, as a result of their mutual gravitational interactions when they pass each other at moderate distances. Jeans developed this idea mathematically and used it to attempt estimates of the ages of stellar systems.

Beginning in 1917, A. S. Eddington developed a theory of the internal constitution of stars. Jeans contributed the observation that because the internal matter of the stars should be highly ionized, the mean molecular weight, which enters into Eddington’s equations, should be much smaller than it would be if the atoms were not ionized. Eddington’s theory, treating the radiative equilibrium of a gaseous star, gave, as a result, a unique relation between mass and luminosity. Jeans believed that such a unique relation was spurious because it ignored the source of stellar energy, which he concluded to be a type of radioactive process involving massive atoms and independent of the temperature of the star’s interior. According to Jeans, the interior matter of these stars would progressively become more ionized and denser, causing the star to evolve from a red giant through a main sequence stage to a white dwarf. With the aid of stability arguments, he concluded that the material in stars could not obey the ideal gas law in their interiors, and he investigated the structure and stability of “liquid” stars, the substance of which does not behave like a gas.

Quotations: "The stream of knowledge is heading towards a non-mechanical reality; the Universe begins to look more like a great thought than like a great machine. Mind no longer appears to be an accidental intruder into the realm of matter... we ought rather hail it as the creator and governor of the realm of matter."

"I incline to the idealistic theory that consciousness is fundamental, and that the material universe is derivative from consciousness, not consciousness from the material universe... In general the universe seems to me to be nearer to a great thought than to a great machine. It may well be, it seems to me, that each individual consciousness ought to be compared to a brain-cell in a universal mind."

"Finite picture whose dimensions are a certain amount of space and a certain amount of time; the protons and electrons are the streaks of paint which define the picture against its space-time background. Traveling as far back in time as we can, brings us not to the creation of the picture, but to its edge; the creation of the picture lies as much outside the picture as the artist is outside his canvas. On this view, discussing the creation of the universe in terms of time and space is like trying to discover the artist and the action of painting, by going to the edge of the canvas. This brings us very near to those philosophical systems which regard the universe as a thought in the mind of its Creator, thereby reducing all discussion of material creation to futility."

Membership

In 1907 Jeans was elected a fellow of the Royal Society. He was elected a secretary of the Royal Society for 1919-1929, during which time he was instrumental in improving the quality of the physical section of the Proceedings. He was vice-president of the Royal Society for 1938-1940, president of the Royal Astronomical Society for 1925-1927, and president of the British Association for the Advancement of Science meeting at Aberdeen in 1934. He also became a director of the Royal Academy of Music in 1938.

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  Fellow

  Royal Society , United Kingdom

  1907 - 1946

Personality

Jeans was known as a rather shy and aloof person. He was also profoundly interested in music - not just the physics of music (about which he wrote a masterful book, Science and Music), but performance as well. He was a more than competent organist, mastering the complete organ repertoire of J. S. Bach, and installing a three-manual organ in his house in Dorking in Surrey, south of London.

Physical Characteristics: While in college, Jeans contracted tubercular infection of the joints, but later recovered.

Interests

• music

Connections

Jeans was married to an American from a wealthy family, Charlotte Tiffany Mitchell. They had one daughter. His first wife died in 1934, and in 1935 he married Suzanne Hock, a concert organist. The couple had three children.

Father:

William Tullock Jeans

Mother:

Martha Ann Hopwood

Spouse:

Suzanne Hock

Sister:

Margaret Louise Jeans

Sister:

Gertrude Mary Jeans

late spouse:

Charlotte Tiffany Mitchell

Daughter:

Katharine Jeans

Daughter:

Olivia Jeans

Grandfather:

John Jeans

grandmother:

Margaret Jeans Stephen

Grandfather:

James Hopwood

grandmother:

Hannah Hopwood

Uncle:

James Stephen Jeans

Uncle:

John Hopwood

aunt:

Lucy Elizabeth Bartle Hopwood

aunt:

Mary Hopwood

aunt:

Sarah Hopwood

aunt:

Robina Jeans

aunt:

Isabella Jeans

aunt:

Mary Jeans

aunt:

Jane Jeans

mentor:

Joseph John Thomson

opponent:

Samuel Hawksley Burbury

Acquaintance:

Walter Sydney Adams

Acquaintance:

Edwin Powell Hubble

References

• Dictionary of Scientific Biography, Volume 7
  1973