A test of the assumption that the redshifts of distant galaxies imply that the Universe is expanding. If the Universe is expanding, the surface brightness of galaxies should decrease rapidly with redshift. In fact, the surface brightness of galaxies does not decrease as rapidly as the Tolman test predicts, but most astronomers assume that this is because galaxies were brighter in the past because of galaxy evolution. The test is named after the American physicist Richard Chace Tolman (1881–1948), who first proposed it in 1930.
Subjects: Astronomy and Astrophysics.