British mathematician and scientist. In
physics he worked on the kinetic theory of gases, and on forms of energy
radiation; in astronomy, his work focused on giant and dwarf stars,
the nature of spiral nebulae, and the origin of the cosmos. He did much
to popularize astronomy.
Jeans was born in Ormskirk, Lancashire, and studied at Cambridge. From
1905 to 1909 he was professor of applied mathematics at Princeton University
in the USA, and lectured at Cambridge 1910-12. Thereafter he devoted
himself to private research and writing, although he was a research
associate at Mount Wilson Observatory, California, 1923-44.
In 1905 Jeans formulated the Rayleigh-Jeans law, which describes the
spectral distribution of black-body radiation (previously studied by
English physicist Lord Rayleigh) in terms of wavelength and temperature.
For some time thereafter Jeans investigated various problems in quantum
theory, but in about 1912 he turned his attention to astrophysics. In
1928 he stated his belief that matter was continuously being created
in the universe (a forerunner of the steady-state theory).
His Dynamical Theory of Gases 1904 became a standard text.