Abstract

Relativistic models of an expanding universe followed by contraction, or a big bang followed by a big crunch, were first proposed by A. Friedmann in 1922 and nine years later by A. Einstein. In the period ca. 1922–1960, the more speculative idea of a large and possibly infinite number of cycles was discussed by R. Tolman in particular. To some cosmologists, the idea was philosophically appealing because it seemed to justify an eternal yet dynamic universe without an absolute beginning in time. During the 1950s models of this kind, sometimes known as Phoenix models, were investigated by a few cosmologists of whom the most important were A. Dauvillier, W. Bonnor, and H. Zanstra.