English physicist who theoretically investigated stellar interiors. He calculated that the temperature at the center of the Sun would have to be in the millions of degrees Kelvin, and published the mass-luminosity law for stars in 1924. He also worked out the causes for brightness variations in Cepheid variables. On theoretical grounds, he predicted that Betelgeuse would have an angular diameter as large as 0.051 arc seconds.

Eddington was one of the first to appreciate the importance of Einstein's theories of special and general relativity, and published a treatise on the subject. He led an expedition to observed the total solar eclipse of 1919, in which the bending of light rays predicted by general relativity was observed (although it was later shown that the uncertainties were too large to make any definitive statement).

Eddington was arrogant, and in his later years, cooked up pseudoscientific "proofs" on "physical" grounds that the fine structure constant was exactly 1/136. When experiments yielded a more accurate value, Eddington produced another proof "proving" that . Eddington also disputed Chandrasekhar's use of electron degeneracy pressure to derive the Chandrasekhar mass limit for a white dwarf, insisting that Chandrasekhar failed to understand the difference between "standing" and "progressing" electron waves.

He devoted the last years of his life to writing popular books, and claimed that the number of electrons in the universe is exactly , a quantity now known as the Eddington number.

Chandrasekhar

Additional biographies: MacTutor (St. Andrews), Bruce Medalists, Bonn