Georges Lemaître

In 1927 Lemaitre published a paper in the Annals of the Scientific Society of Brussels showing that the equations of general relativity permit a universe of constant mass and increasing radius, and deriving from it the relation between a galaxy's distance and the speed at which it recedes. He estimated the constant of proportionality from data then available. Two years later Edwin Hubble published the observational relation, and it carries Hubble's name.

The Brussels journal was not read. Einstein, when Lemaitre described the work to him at the 1927 Solvay conference, is reported to have said that the calculations were correct but the physics abominable. Arthur Eddington, who had supervised Lemaitre at Cambridge, arranged for an English translation in the Monthly Notices of the Royal Astronomical Society in 1931.

That translation is missing the paragraph containing the velocity distance relation and the estimate of the constant, and for eighty years the omission was widely assumed to be an act of suppression by someone protecting Hubble's priority. In 2011 Lemaitre's own correspondence with the journal settled it: he removed the passage himself, telling the editor there was no point reprinting a provisional estimate when much better observational data had since become available. He does not appear to have cared who got the credit, which is unusual enough to be worth recording.

On 22 November 1951 Pope Pius XII addressed the Pontifical Academy of Sciences on the proofs of the existence of God in the light of modern natural science. Drawing on the expanding universe and on the age estimates then current, he argued that science had arrived at a moment when the cosmos began, and that this pointed to a creation and therefore to a Creator. It was reported around the world as the church endorsing the new cosmology.

Lemaitre, who was a member of the Academy and whose hypothesis was being used, thought this was a mistake, and said so. His consistent position was that the primeval atom was a physical hypothesis, that it stood or fell on physical evidence, and that it was entirely outside any metaphysical or religious question. The beginning of the expansion was not the creation of Genesis, and to bind a doctrine to a scientific model was to leave the doctrine hostage to the next observation. He put the case to the pope through the director of the Vatican Observatory, Daniel O'Connell, and the two men spoke with Pius XII.

Pius XII addressed the International Astronomical Union in Rome the following September and did not repeat the argument. The atlas records the episode because both parties behaved better than the story usually allows: a pope who was told he had overreached and dropped it, and a priest who declined to let his own theory be used as an apologetic when he thought the use was unsound.