Although a complete, self-consistent, and accurate description of our Universe is impractical considering the complex multi-scale and multi-physics requirements, a number of enlightening results have been demonstrated through computations. For example, both monotonic AVTD and chaotic oscillatory BLK behavior have been found in the asymptotic approach to the initial singularity in a number of inhomogeneous cosmological models, though some issues remain concerning the generic nature of the singularity, including the effect of nonlinear mode coupling of spatial gradients to the oscillatory history, and the behavior in non-vacuum spacetimes with arbitrary global topology. Numerical calculations suggest that scalar fields play an important complicated role in the nonlinear or chaotic evolution of cosmological models with consequences for the triggering (or not) of inflation and the subsequent dynamics of structure formation. It is possible, for example, that these fields can influence the details of inflation and have observable ramifications as fractal patterns in the density spectrum, gravitational waves, galaxy distribution, and cosmic microwave background anisotropies. All these effects require further studies. Numerical simulations have also been used to place limits on curvature anisotropies and cosmological parameters at early times by considering primordial nucleosynthesis reactions in anisotropic and inhomogeneous cosmologies.
Finally, the large collection of calculations
performed of the post-recombination epoch related to large scale
structure formation (for example, cosmic microwave background,
gravitational lensing, Ly
absorption, and galaxy cluster simulations) have placed strong
constraints on the standard model parameters and structure
formation scenarios when compared to observations. Considering
the range of models consistent with inflation, the preponderance
of observational, theoretical and computational data suggest a
best fit model of the late structure-forming Universe that is
spatially flat with a cosmological constant and a small tilt in
the power spectrum. These best fit model parameters, and in
particular the introduction of a cosmological constant, are
generally consistent with recent evidence of dark energy from
supernovae and high precision CMBR observations.
Obviously many fundamental issues remain unresolved, including even the overall shape or topology of the cosmological model which best describes our Universe throughout its entire history. However, the field of numerical cosmology has matured in the development of computational techniques, the modeling of microphysics, and in taking advantage of current trends in computing technologies, to the point that it is now possible to perform high resolution multiphysics simulations and carry out reliable comparisons of numerical models with observational data.
![]() |
http://www.livingreviews.org/lrr-2001-2 | © Max Planck Society and
the author(s)
Problems/comments to |