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James Hopwood Jeans

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James Hopwood Jeans
Born	11 September 1877 Ormskirk, Lancashire, England
Died	16 September 1946 (aged 69) Dorking, Surrey, England
Nationality	British
Fields	astronomy, mathematics, physics
Institutions	Trinity College, Cambridge; Princeton University
Alma mater	Merchant Taylors' School; Cambridge University
Notable students	Ronald Fisher
Known for	Rayleigh–Jeans law Jeans mass Jeans length
Notable awards	Adams Prize (1917) Royal Medal (1919)

Sir James Hopwood Jeans OM FRS^[1] MA DSc ScD LLD^[2] (11 September 1877 – 16 September 1946^[3]) was an English physicist, astronomer and mathematician.

Contents

• 1 Background
• 2 Major accomplishments
• 3 Awards and honours
• 4 Bibliography
• 5 References
• 6 External links

Background

Born in Ormskirk, Lancashire, Jeans was educated at Merchant Taylors' School, Northwood, Wilson's Grammar School,^[4] Camberwell and Trinity College, Cambridge.^[5] His coach for Cambridge Mathematical Tripos was Robert Alfred Herman, and in 1898 he came out Second Wrangler. Jeans was elected Fellow of Trinity College in October 1901,^[6] and taught at Cambridge, but went to Princeton University in 1904 as a professor of applied mathematics. He returned to Cambridge in 1910.
He made important contributions in many areas of physics, including quantum theory, the theory of radiation and stellar evolution. His analysis of rotating bodies led him to conclude that Laplace's theory that the solar system formed from a single cloud of gas was incorrect, proposing instead that the planets condensed from material drawn out of the sun by a hypothetical catastrophic near-collision with a passing star. This theory is not accepted today.
Jeans, along with Arthur Eddington, is a founder of British cosmology. In 1928 Jeans was the first to conjecture a steady state cosmology based on a hypothesized continuous creation of matter in the universe.^[7] This theory was ruled out when the 1965 discovery of the cosmic microwave background was widely interpreted as the tell-tale signature of the Big Bang.
His scientific reputation is grounded in the monographs The Dynamical Theory of Gases (1904), Theoretical Mechanics (1906), and Mathematical Theory of Electricity and Magnetism (1908). After retiring in 1929, he wrote a number of books for the lay public, including The Stars in Their Courses (1931), The Universe Around Us, Through Space and Time (1934), The New Background of Science (1933), and The Mysterious Universe. These books made Jeans fairly well known as an expositor of the revolutionary scientific discoveries of his day, especially in relativity and physical cosmology.
In 1939, the Journal of the British Astronomical Association reported that Jeans was going to stand as a candidate for parliament for the Cambridge University constituency. The election, expected to take place in 1939 or 1940 did not take place until 1945, and without his involvement.
He also wrote the book "Physics and Philosophy" (1943) where he explores the different views on reality from two different perspectives: science and philosophy.
On his religious views, Jeans was an agnostic Mason.^{[8] [9]}

Jeans married twice, first to the American poet Charlotte Tiffany Mitchell in 1907,^[10] then the Austrian organist and harpsichordist Suzanne Hock (better known as Susi Jeans) in 1935. He died in Dorking, Surrey.
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 but notably in Mathematics and Sciences.

Major accomplishments

One of Jeans' major discoveries, named Jeans length, is a critical radius of an interstellar cloud in space. It depends on the temperature, and density of the cloud, and the mass of the particles composing the cloud. A cloud that is smaller than its Jeans length will not have sufficient gravity to overcome the repulsive gas pressure forces and condense to form a star, whereas a cloud that is larger than its Jeans length will collapse.

Jeans 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.
Jeans also helped to discover the Rayleigh–Jeans law, which relates the energy density of blackbody radiation to the temperature of the emission source.

Awards and honours

• Fellow of the Royal Society in May, 1906
• Bakerian Lecture to Royal Society in 1917.
• Royal Medal of the Royal Society in 1919.
• Hopkins Prize of the Cambridge Philosophical Society 1921–1924.
• Gold Medal of the Royal Astronomical Society in 1922.
• He was knighted in 1928.
• Franklin Medal of the Franklin Institute in 1931.
• In 1933 Hopwood-Jeans was invited to deliver the Royal Institution Christmas Lecture on Through Space and Time.
• Mukerjee Medal of the Indian Association for the Cultivation of Science in 1937.
• President of the 25th session of the Indian Science Congress in 1938.
• Calcutta Medal of the Indian Science Congress Association in 1938.
• Member of the Order of Merit in 1939.
• 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.

Bibliography

• Jeans, James Hopwood. (1947). The Growth of Physical Science. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00565-4)
• Jeans, James Hopwood. (1942). Physics and Philosophy. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00567-8)
• Jeans, James Hopwood. (1940). An Introduction to the Kinetic Theory of Gases. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00560-9)
• Jeans, James Hopwood. (1937). Science and Music. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00569-2)
• Jeans, James Hopwood. (1934). Through Space and Time. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00571-5)
• Jeans, James Hopwood. (1933). The New Background of Science. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00572-2)
• Jeans, James Hopwood. (1931). Stars in Their Courses. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00570-8)
• Jeans, James Hopwood. (1930). The Mysterious Universe. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00566-1)
• Jeans, James Hopwood. (1928). Astronomy and Cosmogony. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00562-3)
• Jeans, James Hopwood. (1925). Mathematical Theory of Electricity and Magnetism. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00561-6)
• Jeans, James Hopwood. (1926). Atomicity and Quanta. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00563-0)
• Jeans, James Hopwood. (1919). Problems of Cosmology and Stellar Dynamics. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00568-5)
• Jeans, James Hopwood. (1904). The Dynamical Theory of Gases. Cambridge University Press (reissued by Cambridge University Press, 2009; ISBN 978-1-108-00564-7)

Available online from the Internet Archive

• 1904. The Dynamical Theory of Gases
• 1906. Theoretical Mechanics
• 1908. Mathematical Theory of Electricity and Magnetism
• 1947. The Growth of Physical Science

Other:

• 1929. The Universe Around Us
• 1930. The Mysterious Universe
• 1931. The Stars in Their Courses
• 1933. The New Background of Science
• 1937. Science and Music
• 1942. Physics and Philosophy