Einstein's Blackboard

Einstein's Blackboard is a blackboard which physicist Albert Einstein (1879–1955) used on 16 May 1931 during his lectures while visiting the University of Oxford in England.The blackboard is one of the most iconic objects in the collection of the Museum of the History of Science in Oxford.

The lecture in which the blackboard was used was the second of three, delivered at Rhodes House in South Parks Road. Einstein's visit to give the Rhodes Lectures, and also to receive an honorary Doctor of Science degree from Oxford University on 23 May 1931, was hosted by the physicist Frederick Lindemann.^[ Einstein's first lecture was on relativity, the second on cosmology, and the third on unified field theory. All the lectures were delivered in German. A brief report of the second lecture was given in The Times and in Nature. A summary of all three lectures can be found in the Archives of the Oxford Museum for the History of Science.^[8]

The blackboard was rescued with another by dons (including the chemist E. J. Bowen, zoologist Gavin de Beer, and historian of science Robert Gunther) and formally donated by the Warden of Rhodes House, Sir Francis James Wylie. The writing on the blackboard, although ephemeral in nature, is of historic interest because the equations displayed are taken from a model of the universe proposed by Einstein in May 1931 known as The Friedmann-Einstein universe. The last three lines on the blackboard are estimates of the density of matter in the universe ρ, the radius of the universe P and the timespan t of the expansion of the universe respectively ("L.J." on the blackboard indicates "light years" in German). It has recently been shown that these estimates contain a systematic numerical error.

The blackboard is considered a "mutant" object or artefact in that it is very different from most of the objects in the collection of the museum (mainly scientific instruments such as astrolabes).A second blackboard used by Einstein during the lecture is also in the collection of the Museum of the History of Science, but is not on display. However it is of less interest because it was wiped clean after the lecture.

Einstein returned to Oxford again in 1932 and 1933 before he settled at Princeton University in the United States for the rest of his life.