During the 1930s other ideas were proposed as non-standard cosmologies to explain Hubble's observations, including the Milne model, the oscillatory universe (originally suggested by Friedmann, but advocated by Albert Einstein and Richard Tolman) and Fritz Zwicky's tired light hypothesis.
Durante os anos 1930, outras ideas propuxéronse como cosmoloxías non estándares para explicar as observacións de Hubble, incluíndo o modelo de Milne, o universo oscilante (orixinalmente suxerido por Friedmann, pero apoiado por Einstein e Richard Tolman) e a hipótese da luz cansa de Fritz Zwicky.