A 120-MPC PERIODICITY IN THE 3-DIMENSIONAL DISTRIBUTION OF GALAXY SUPERCLUSTERS

ACCORDING to the favoured models for the formation of large-scale stru cture in the Universe (in which the dynamics of the Universe is domina ted by cold dark matter), the distribution of galaxies and clusters of galaxies should be random on large scales, It therefore came as a sur prise when a periodicity was reported(1) in the distribution of high-d ensity regions of galaxies in the directions of the Galactic poles, al though the apparent lack of periodicity in other directions led to the initial report being regarded as a statistical anomaly(2). A subseque nt study(3-6) also claimed evidence for periodicity on the same stale, but the statistical significance of this result was uncertain due to the small number of clusters used, Here, using a new compilation(7) of available data on galaxy clusters, we present evidence for a quasireg ular three-dimensional network of rich superclusters and voids, with t he regions of high density separated by similar to 120 Mpc, If this re flects the distribution of all matter (luminous and dark), then there must exist some hitherto unknown process that produces regular structu re on large scales.