"[T]wo rather separate research agendas emerged... [1] investigations of what were to become the three classical tests, envisaged by Einstein as early as 1907. ...[2] investigations of cosmological issues, whose only observational basis was the observations. Of the classical tests, both the bending of light and the remained controversial matters until the renaissance... This research agenda involved a small number of astronomers... not necessarily focused on general relativity. The cosmological research involved a separate group, consisting mostly of mathematicians like Howard Robertson and and astronomers with strong mathematical training such as Eddington, Lemaître, George McVittie, and William McCrea. They were mainly interested in how to apply general relativity to cosmological problems, which involved not only understanding cosmic dynamics but also solving the intricate problem of interpreting cosmological solutions to the Einstein equations, in particular separating time (which determined the evolution of the universe) from space (to which simplified assumptions concerning the structure of the universe, such as homogeneity and , were to be applied)."