Abraham Taub conducts a systematic study of all universes that are identical at every point in space, but expand at different speeds in different directions. To do this, he uses Bianchi Spaces, named after the famous professor at the Scuola Normale Superiore in Pisa and Italian mathematician Luigi Bianchi (1856–1928). There are nine Bianchi Spaces or Universes, the most complex of which have both curvature and anisotropic expansion and gravitational waves. The interest of Bianchi Spaces lies in trying to explain why the cosmic microwave background radiation is so isotropic across the entire sky. Bianchi Spaces or Universes possess four characteristics that make them different, more complicated, and bizarre than the simple universes of Friedmann, Lemaitre, and de Sitter: shear deformation, rotation, velocity relative to the Hubble expansion, and anisotropic curvature.
