Einstein’s Oxford cosmology blackboards: open portals to 1931

We give a detailed description of the May 16, 1931, lecture by Albert Einstein on cosmology at Oxford University. In this lecture, Einstein discussed his cosmological model of 1931, a model in which the universe was assumed to expand from zero size to a maximum size and then collapse back again. We use information from the two blackboards that Einstein filled for the lecture and intertwine it with a detailed newspaper transcript of what Einstein said concurrently in German. We thereby present a line-by-line explanation of what was conveyed on the blackboards visually and, in an approximate way, what was concurrently conveyed verbally by Einstein. Even though very few in the audience that day would qualify, we assume the point of view of a sufficiently prepared member of the audience. Our discussion is informed by a summary pamphlet that was handed out by the organizers of the talks. We also describe some mistakes that Einstein made in his talk, issues surrounding the successful preservation of one of the two blackboards, as well as some aspects of Einstein’s cosmological thinking after the talk.