Multifractal Investigation of One Dimensional Models of the Expanding Universe

Bruce Miller, Physics, Texas Christian University

Concentrations of matter in the universe, such as galaxies and galactic clusters, originated as very small density fluctuations in the early universe. The fluctuation spectrum is revealed by studies of the angular correlation of CBM across the sky with WMAP. The existence of galaxy clusters and super-clusters suggests that a natural scale for the matter distribution may not exist. A point of controversy is whether the distribution is fractal and, if so, over what range of scales. The assumed source of fractal behavior is the lack of a length scale in the two body gravitational interaction. However, even with new, larger, sample sizes from recent surveys, it is difficult to extract information concerning fractal properties with confidence. Similarly, simulations with a billion particles only provide a thousand particles per dimension, far too small for accurate conclusions. With one dimensional “toy models” we can overcome these limitations by carrying out simulations with on the order of a quarter of a million particles without compromising the computation of the gravitational force. They clearly demonstrate that the important dynamics for cluster formation occurs in the position-velocity plane. Here we present the recent results of our on-going investigation of the fractal geometry of one dimensional models of the expanding universe. We will provide a preliminary overview of the population spectrum required for a study of possible multifractal behavior.