A simulation following the evolution of a large representative volume of the Universe from just after the Big Bang to the present day. We're looking at the projected gas density from the side of the cube, and our view follows the reference frame of the expanding Universe over this time. As you can see, initially the Universe starts out dense and uniform, but over time slight overdensities in the gas are amplified by the attractive effects of gravity to form the walls, filaments, and clusters seen here. Also note the axes scales change over time as the Universe expands by a factor of 100 between z=100 and z=0, and observe the significant drop in the general column density over that period.
Details: This is a 100 comoving Megaparsec box of a cosmological hydrodynamics simulation incorporating metal cooling, star formation (Cen & Ostriker), stellar feedback (Hummels & Bryan 2012), and a metagalactic UV background (Haardt & Madau 2012) using WMAP9 cosmological parameters. The simulation was conducted with the Enzo AMR hydrodynamics code (Bryan et al. 2014) visualized using the yt analysis suite (Turk et al. 2010).
