Slipher's redshifts as support for de Sitter's model and the discovery\n of the dynamic universe

Of the first two relativistiv world models, only the one by de Sitter\npredicted redshifted spectra from far away astronomical objects. Slipher's\nredshifts therefore seemed to arbitrate against Einstein's model which made no\nsuch predictions. Both models were trying to describe a static universe.\nHowever, Lemaitre found that de Sitter's construct resulted in a spatially\ninhomogeneous universe. He then opted for a model that correspondes to\nEinstein's closed, curved universe but allowed the radius of curvature to\nchange with time. Slipher's redshifts suggested to him that the universe is\ndynamic and expanding. We also discuss the respective merits of Friedman and\nLemaitre in revealing the dynamic nature of the universe.\n