Sir Harold Jeffreys, FRS (22 April 1891 – 18 March 1989) was a British geophysicist who made significant contributions to mathematics and statistics. His book, ''Theory of Probability'', which was first published in 1939, played an important role in the revival of the objective Bayesian view of probability.

Education

Jeffreys was born in Fatfield, County Durham, England, the son of Robert Hal Jeffreys, headmaster of Fatfield Church School, and his wife, Elizabeth Mary Sharpe, a school teacher. He was educated at his father's school and at Rutherford Technical College, then studied at Armstrong College in

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(at that time part of the University of Durham) and with the University of London External Programme.Cook, Alan ev.br>"Jeffreys, Sir Harold (1891–1989)"
''Oxford Dictionary of National Biography'', Oxford University Press, 2004; online edition, September 2004. Retrieved 1 January 2023. Jeffreys subsequently won a scholarship to study the

Mathematical Tripos The Mathematical Tripos is the mathematics course that is taught in the Faculty of Mathematics, University of Cambridge, Faculty of Mathematics at the University of Cambridge. Origin In its classical nineteenth-century form, the tripos was a di ...

St John's College, Cambridge St John's College, formally the College of St John the Evangelist in the University of Cambridge, is a Colleges of the University of Cambridge, constituent college of the University of Cambridge, founded by the House of Tudor, Tudor matriarch L ...

, where he established a reputation as an excellent student: obtaining first-class marks for his papers in Part One of the Tripos, he was a Wrangler in Part Two, and in 1915 he was awarded the prestigious Smith's Prize.

Career

Jeffreys became a fellow of St John's College in 1914, retaining his fellowship until his death 75 years later. At the

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

he taught mathematics, then

geophysics Geophysics () is a subject of natural science concerned with the physical processes and Physical property, properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct i ...

and finally became the Plumian Professor of Astronomy. In 1940, he married fellow mathematician and physicist, Bertha Swirles (1903–1999), and together they wrote ''Methods of Mathematical Physics''. One of his major contributions was on the Bayesian approach to

probability Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an e ...

(also see Jeffreys prior), as well as the idea that the Earth's planetary core was liquid. By 1924 Jeffreys had developed a general method of approximating solutions to linear, second-order differential equations, including the Schrödinger equation. Although the Schrödinger equation was developed two years later, Wentzel, Kramers, and Brillouin were apparently unaware of this earlier work, so Jeffreys is often neglected when credit is given for the WKB approximation. Jeffreys received the Gold Medal of the Royal Astronomical Society in 1937, the

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's Copley Medal in 1960, and the Royal Statistical Society's Guy Medal in Gold in 1962. In 1948, he received the Charles Lagrange Prize from the Académie royale des Sciences, des Lettres et des Beaux-Arts de Belgique. He was knighted in 1953. From 1939 to 1952 he was established as Director of the International Seismological Summary further known as International Seismological Centre. The textbook ''Probability Theory: The Logic of Science,'' written by the physicist and probability theorist Edwin T. Jaynes, is dedicated to Jeffreys. The dedication reads, "Dedicated to the memory of Sir Harold Jeffreys, who saw the truth and preserved it." It is only through an appendix to the third edition of Jeffreys' book ''Scientific Inference'' that we know about Mary Cartwright's method of proving that the number is irrational.

Opposition to continental drift and plate tectonics

Jeffreys, like many of his peers, staunchly opposed the concept of continental drift as put forth by Alfred Wegener and Arthur Holmes. This opposition persisted even into the 1960s among his colleagues at Cambridge. For him, continental drift was "out of the question" because no force even remotely strong enough to move the continents across the Earth's surface was evident. As geological and geophysical evidence for continental drift and

plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

mounted in the 1960s and after, to the point where it became the unifying concept of modern geology, Jeffreys remained a stubborn opponent of the theory to his death.

Honours and awards

* Fellow, Royal Society, 1925 * Adams Prize, 1927 (Constitution of the Earth) * Gold Medal, Royal Astronomical Society, 1937 * Buchan Prize, Royal Meteorological Society, 1929 * Murchison Medal of Geological Society (Great Britain) 1939 * Victoria Medal, Royal Geographical Society, 1941 * Charles Lagrange Prize, Brussels Academy, 1948 * Royal Medal, 1948 * William Bowie Medal, American Geophysical Union, 1952 * Knighted, 1953 * Copley Medal, Royal Society, 1961 * Vetlesen Prize, 1962

Bibliography

* 1924: ''The Earth, Its Origin, History and Physical Constitution'',

Cambridge University Press Cambridge University Press was the university press of the University of Cambridge. Granted a letters patent by King Henry VIII in 1534, it was the oldest university press in the world. Cambridge University Press merged with Cambridge Assessme ...

; 5th edn. 1970; 6th edn. 1976 * 1927
Operational Methods in Mathematical Physics

via

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, Review: * 1929: ''The Future of the Earth'', Norton & Company * 1931: ''Scientific Inference'',

Macmillan Publishers Macmillan Publishers (occasionally known as the Macmillan Group; formally Macmillan Publishers Ltd in the United Kingdom and Macmillan Publishing Group, LLC in the United States) is a British publishing company traditionally considered to be on ...

; 2nd edn. 1937; 3rd edn. 1973 * 1931: ''Cartesian Tensors''. Cambridge University Press; 2nd edn. 1961 * 1934: ''Ocean Waves and Kindred Geophysical Phenomena'', with Vaughan Cornish, Cambridge University Press * 1935: ''Earthquakes and Mountains'', Methuen Publishing; 2nd edn. 1950 * 1939: ''Theory of Probability'',

Clarendon Press Oxford University Press (OUP) is the publishing house of the University of Oxford. It is the largest university press in the world. Its first book was printed in Oxford in 1478, with the Press officially granted the legal right to print books ...

, Oxford; 2nd edn. 1948; 3rd edn. 1961 * 1946: ''Methods of Mathematical Physics'', with Bertha S. Jeffreys. Cambridge University Press; 2nd edn. 1950; 3rd edn. 1956; corrected 3rd edn. 1966 * 1962: ''Asymptotic Approximations'',

, Oxford * 1963: ''Nutation and Forced Motion of the Earth's Pole from the Data of Latitude Observations'', Macmillan * 1971–77: ''Collected Papers of Sir Harold Jeffreys on Geophysics and Other Sciences'', Gordon and Breach

References

External links

*
Photographs of Harold Jeffreys at Emilio Segrè Visual Archives, American Institute of Physics

{{DEFAULTSORT:Jeffreys, Harold 1891 births 1989 deaths Alumni of St John's College, Cambridge Alumni of University of London Worldwide Alumni of the University of London Bayesian statisticians 20th-century British astronomers 20th-century English mathematicians English statisticians Philosophers of probability Fellows of St John's College, Cambridge Fellows of the Royal Society Foreign associates of the National Academy of Sciences Knights Bachelor People from Fatfield Recipients of the Copley Medal Recipients of the Gold Medal of the Royal Astronomical Society Royal Medal winners British seismologists Wollaston Medal winners Analysands of Ernest Jones Presidents of the Royal Astronomical Society Victoria Medal recipients Alumni of Armstrong College, Durham Plumian Professors of Astronomy and Experimental Philosophy British mathematical statisticians Vetlesen Prize winners