Cosmicscale

Cosmicscale is a term used in cosmology to describe spatial scales at which the universe’s large-scale structure becomes statistically uniform and isotropic. It typically encompasses tens to hundreds of megaparsecs (Mpc) and, in broader discussions, gigaparsec scales that define the cosmic web and the extent of the observable universe. On these scales the matter distribution is described by the cosmological principle rather than by individual galaxies or clusters.

Cosmicscale structure is probed with galaxy redshift surveys and measurements of the cosmic microwave background. The cosmic web consists of filaments, walls, and voids spanning roughly 10–100 Mpc, with clustering characterized by the two-point correlation function and a baryon acoustic oscillation (BAO) feature at about 150 Mpc, used as a standard ruler. The approach seeks the transition to statistical homogeneity around roughly 100–300 Mpc, depending on data and method.

The concept supports the standard cosmological model (ΛCDM) and informs estimates of the Hubble constant, matter density, and dark energy by comparing observations across cosmic time. It also frames interpretations of large-scale anomalies in the CMB and peculiar velocity fields.

Limitations include cosmic variance and survey geometry, which complicate precise delimitation of cosmicscale. See also large-scale structure, cosmological principle, BAO, cosmic web, and Hubble radius.