(1882-1944), Knight, theoretical physicist and astrophysicist

Sir Arthur Stanley Eddington, born on 28 December 1882, in Westmorland, England accomplished his greatest work in astrophysics, investigating the motion, internal structure, and evolution of stars. He also was the first expositor of the theory of relativity in the English language.

He received his schooling in Weston-super-Mare in Somerset and entered Trinity College, Cambridge, in October 1902. There he won every mathematical honour, as well as Senior Wrangler (1904), Smith’s prize, and a Trinity College fellowship (1907). In 1913 he received the Plumian Professorship of Astronomy at Cambridge and in 1914 became also the director of its observatory. From 1906 to 1913 Eddington was chief assistant at the Royal Observatory at Greenwich, where he gained practical experience in the use of astronomical instruments. He made observations on the island of Malta to establish its longitude, led an eclipse expedition to Brazil, and investigated the distribution and motions of the stars. In Stellar Movements and the Structure of the Universe (1914) he summarized his mathematically elegant investigations of the motions of stars in the Milky Way.

He carried out important studies in astrophysics and relativity, in addition to teaching and lecturing. In 1919 he led an expedition to Príncipe Island (West Africa) that provided the first confirmation of Einstein’s theory that gravity will bend the path of light when it passes near a massive star. During the total eclipse of the sun, it was found that the positions of stars seen just beyond the eclipsed solar disk were, as the general theory of relativity had predicted, slightly displaced away from the centre of the solar disk. Eddington was the first expositor of relativity in the English language. His Report on the Relativity Theory of Gravitation (1918), written for the Physical Society, followed by Space, Time and Gravitation (1920) and his great treatise The Mathematical Theory of Relativity (1923)—the latter considered by Einstein the finest presentation of the subject in any language—made Eddington a leader in the field of relativity physics.

Eddington received many honours, including honorary degrees from 13 universities. He was president of the Royal Astronomical Society (1921–23), the Physical Society (1930–32), the Mathematical Association (1932), and the International Astronomical Union (1938–44). He was knighted in 1930 and received the Order of Merit in 1938. Meetings of the Royal Astronomical Society were often enlivened by dramatic clashes between Eddington and Sir James Hopwood Jeans or Edward Arthur Milne over the validity of scientific assumptions and mathematical procedures.

Eddington’s greatest contributions were in the field of astrophysics and are represented by the classic Internal Constitution of the Stars (1925) and in the public lectures published as Stars and Atoms (1927). His theoretical work in physics had a stimulating effect on the thought and research of others, and many lines of scientific investigation were opened as a result of his work. He died in Cambridge on the 22 November 1944.