Froth across the Universe Dynamics and Stochastic Geometry of the Cosmic Foam

Abstract

A review on the properties and dynamical origin and nature of the cosmic foam, the tenuous space-filling frothy network permeating the interior of the Universe. We discuss the properties of this striking and intriguing pattern, describing its observational appearance, and seeking to elucidate its dynamical origin and nature. An extensive discussion on the gravitational formation and dynamical evolution of weblike patterns puts particular emphasis on the formative role of the generic anisotropy of the cosmic gravitational force fields. These tidal fields play an essential role in shaping the pattern of the large scale cosmic matter distribution. Special attention is put on a geometrical and stochastic framework for a systematic evaluation of its fossil information content on the cosmic structure formation process. Its distinct geometric character and the stochastic nature provides the cosmic web with some unique and at first unexpected properties. The implications for galaxy clustering are discussed on the basis of its relevant branch of mathematics, stochastic geometry. Central within this context are Voronoi tessellations, which have been found to represent a surprisingly versatile model for spatial cellular distributions.Comment: Invited review, Proceedings 2nd Hellenic Cosmology Workshop, eds. M. Plionis, S. Cotsakis, I. Georgantopoulos, Kluwer, 153 pages, 56 figures. Full resolution version available at http://www.astro.rug.nl/~weygaert/tim1publication/weyhellas2001.ps.g