Eddington, Lemaitre and the hypothesis of cosmic expansion

Arthur Stanley Eddington was one of the leading astronomers and theorists of his generation and a prominent proponent of the general theory of relativity. Yet when his former assistant Georges Lemaitre sent him a paper in 1927 suggesting that the well-known redshifts of the spiral nebulae might be a manifestation of a cosmic expansion predicted by relativity, Eddington paid no attention for three years. In this paper, we consider the reasons for this oversight. We find that conventional explanations (such as Lemaitre’s status as a relatively junior researcher and his decision to publish in a lesser-known Belgian journal) do not convince. We propose an alternative explanation that has not been considered in the literature - namely that the observational data cited by Lemaitre in support of his model were of a preliminary nature and would not have been sufficiently convincing for Eddington and others to consider non-static cosmologies.