From Time Machine
Direct cosmological simulations of the growth of black holes and galaxies
This timelapse was shows the distribution of matter in a simulated universe on large scales. The computer simulation (name: BHCosmo) was carried out on the Cray XT3 at the Pittsburgh Supercomputer Center by Tiziana Di Matteo (CMU) and the visualization by Yu Feng and Rupert Croft on facilities provided by the Moore foundation in the McWilliams Center for Cosmology at CMU. The full image is 600 million light years in width and the density of matter is being shown on a false color scale, with the densest regions in yellow and the least dense in red and black. Unlike images of the real Universe seen through optical telecopes, in the simulated image it is possible to see the filmentary structures that stretch through the space between galaxies. These structures contain mostly hydrogen and helium gas. The only luminous matter is in galaxies, which are much sparser. To see these, we need to move forward in time to the universe at late times (when stars have formed) and zoom in. Then small blobs of gas become apparent with white points (stars) in, and dark blue gas (which signifies gas that is actively forming stars). These blobs of gas and stars are whole galaxies, and there are several thousand of them in this image, a hundred or so the size of the Milky Way and many much smaller. As the universe evolves from early times (it starts at an age of two hundred million years after the Big Bang) the initially small fluctuations grow through the action of gravity until in the last frame (which represents the universe 7 billion years later, at redshift z=1) there are large clusters of galaxies present with vast, mostly empty spaces in between.
To carry out the simulation the equations of gravity, hydrodynamics, radiative cooling, and models for star formation and black hole growth were solved in parallel on a system of 230 million particles. The ingredients that make up the universe are dark matter, dark energy (in the observed proportions), 4% of normal (atomic) matter, and small initial flucutations created during the inflationary epoch when the whole of the presently observed universe was smaller than the size of an atom.
More details in: Di Matteo et al., http://arxiv.org/abs/0705.2269