|Slipher's Redshifts as Support for de Sitter's Model and the Discovery of the Dynamic Universe
|471, Origins of the Expanding Universe: 1912-1932
|Of the first two relativistic world models, only the one by de Sitter
predicted redshifted spectra from far away astronomical objects. Slipher's
redshifts therefore seemed to arbitrate against Einstein's model which made no
such predictions. Both models were trying to describe a static universe.
However, Lemaître found that de Sitter's construct resulted in a spatially
inhomogeneous universe. He then opted for a model that corresponded to
Einstein's closed, curved universe but allowed the radius of curvature to change
with time. Slipher's redshifts suggested to him that the universe is dynamic and
expanding. We also discuss the respective merits of Friedman and Lemaître in
revealing the dynamic nature of the universe.