Eddington argued that the value of the
fine-structure constant,
α, could be obtained by pure deduction. He related
α to the Eddington number, which was his estimate of the number of protons in the universe. This led him in 1929 to conjecture that
α was exactly 1/136. He devised a "proof" that , or about . Other physicists did not adopt this conjecture and did not accept his argument. It even led to a major journal publishing a joke article making fun of the idea. During a course of lectures that he delivered in 1938 as
Tarner Lecturer at
Trinity College, Cambridge, Eddington averred that: This large number was soon named the "Eddington number". Shortly thereafter, improved measurements of
α yielded values closer to 1/137, whereupon Eddington changed his "proof" to show that
α had to be exactly 1/137. Current estimates of
NEdd point to a value of about . These estimates assume that all matter can be taken to be
hydrogen and require assumed values for the number and size of
galaxies and
stars in the universe. == See also ==