Einstein’s conversion from a static to an expanding universe (Vol. 45 No.2)

Einstein and Lemaître photographed around 1933.
Credit: Archives Lemaître, Université Catholique, Louvain

Albert Einstein accepted the modern cosmological view that the universe is expanding, only long after several of his contemporaries had demonstrated it with astrophysical observations.

Until 1931, physicist Albert Einstein believed that the universe was static, in line with his 1917 model. Now, the author explains how Einstein changed his mind and adopted the notion of an expanding universe following many encounters with some of the most influential astrophysicists of his generation.

He then fiercely resisted the view that the universe was expanding. For example, in 1922, Alexander Friedman showed that Einstein’s equations were viable for dynamical worlds. And, in 1927, Georges Lemaître, concluded that the universe was expanding by combining general relativity with astronomical observations.

It is only by April 1931 that Einstein finally adopted a model of an expanding universe. In 1932 he teamed up with Willem de Sitter, to propose an eternally expanding universe. This became the cosmological model generally accepted until the middle of the 1990s.

H. Nussbaumer, “Einstein’s conversion from his static to an expanding universe”, Eur. Phys. J. H, 39, 37 (2014)
[Abstract]