4 Physical Cosmology 

The phrase ``physical cosmology'' is generally associated with the large (galaxy and cluster) scale structure of the post-recombination epoch where gravitational effects are modeled approximately by Newtonian physics on an uniformly expanding, matter dominated FLRW background. A discussion of the large scale structure is included in this review since any viable model of our Universe which allows a regime where strongly general relativistic effects are important must match onto the weakly relativistic (or Newtonian) regime. Also, since certain aspects of this regime are directly observable, one can hope to constrain or rule out various cosmological models and/or parameters, including the density (), Hubble ( km sec Mpc ), and cosmological () constants.

Due to the vast body of literature on numerical simulations of the post-recombination epoch, it is possible to mention only a small fraction of all the published papers. Hence, the following summary is limited to cover just a few aspects of computational physical cosmology, and in particular those that can potentially be used to discriminate between cosmological model parameters, even within the realm of the standard model.

• 4.1 Microwave Background
• 4.2 Gravitational Lensing
• 4.3 First Star Formation
• 4.4 Lyman-alpha Forest
• 4.5 Galaxy Clusters
• 4.6 Cosmological Sheets

Computational Cosmology: from the Early Universe to the Large Scale Structure Peter Anninos http://www.livingreviews.org/lrr-1998-9 © Max-Planck-Gesellschaft. ISSN 1433-8351 Problems/Comments to livrev@aei-potsdam.mpg.de