Eddington, Sir Arthur Stanley (1882-1944), a British astronomer, pioneered in the investigation of the internal structure of stars. In 1924, Eddington demonstrated a fundamental relationship between the mass and brightness of a star. In most cases, the more mass a star has, the brighter it is. Eddington also wondered what prevents a star from collapsing inward under its own gravitational pressure. In 1926, he showed that such a collapse is prevented by outward pressure produced by light and other electromagnetic radiation inside the star and by the gas of which the star is composed.
Eddington was the leading campaigner in the United Kingdom for acceptance of the general theory of relativity, a set of ideas proposed by the German-born physicist Albert Einstein. The theory deals with the physical laws that govern time, space, mass, motion, and gravitation. During a solar eclipse in 1919, Eddington led a team at Principe Island, off the coast of Africa, that detected a slight bending of starlight by the sun’s gravitational field. The bending was twice that predicted by the English scientist Sir Isaac Newton’s law of gravity. This observation supported Einstein’s theory, which had predicted that effect. Einstein judged Eddington’s textbook, The Mathematical Theory of Relativity, published in 1923, “the finest presentation of the subject in any language.”
In 1978, looking ahead to the 1979 celebration of Einstein’s 100th birthday, scientists reanalyzed Eddington’s data from the Principe Island eclipse using a modern measuring device and computer software. The reanalysis confirmed that Eddington was correct in his conclusions regarding general relativity. Since 1919, general relativity has been confirmed through several other means, including the study of the planet Mercury’s orbit and how a magnetic field affects the color of light.
Eddington was born on Dec. 28, 1882, at Kendal, England. He studied at Manchester and Cambridge universities and directed the Cambridge University Observatory from 1914 to 1944. He died on Nov. 22, 1944.
