Redshift quantization, also referred to as redshift periodicity,[1]redshift discretization,[2]preferred redshifts[3] and redshift-magnitude bands,[4][5] is the hypothesis that the redshifts of cosmologically distant objects (in particular galaxies and quasars) tend to cluster around multiples of some particular value.
In standard inflationary cosmological models, the redshift of cosmological bodies is ascribed to the expansion of the universe, with greater redshift indicating greater cosmic distance from the Earth (see Hubble's law). This is referred to as cosmological redshift and is one of the main pieces of evidence for the Big Bang. Quantized redshifts of objects would indicate, under Hubble's law, that astronomical objects are arranged in a quantized pattern around the Earth. It is more widely posited that the redshift is unrelated to cosmic expansion and is the outcome of some other physical mechanism, referred to as "intrinsic redshift" or "non-cosmological redshift".
In 1973, astronomer William G. Tifft was the first to report evidence of this pattern. Subsequent discourse focused upon whether redshift surveys of quasars (QSOs) have produced evidence of quantization in excess of what is expected due to selection effect or galactic clustering.[6][7][8][9] The idea has been on the fringes of astronomy since the mid-1990s and is now discounted by the vast majority of astronomers, but a few scientists who espouse nonstandard cosmological models, including those who reject the Big Bang theory, have referred to evidence of redshift quantization as reason to reject conventional accounts of the origin and evolution of the universe.[10][11][12]
Barnothy, J. M.; Barnothy, M. F. (1980). "The Redshift Periodicity of QSO's and the Origin of Cosmic Radiation". Bulletin of the American Astronomical Society. 12: 852. Bibcode:1980BAAS...12..852B.