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Formation of superclusters may be the next stage in a process that is shaping and forming fundamental units in the universe. It is believed that the process began after the Big Bang, when matter in the universe expanded out rapidly. Some matter clumped together to form stars. Then gravity took over and the stars formed galaxies, then groups, then clusters and, now, superclusters. The supercluster formation occurring now is at an early stage. These objects may be at the critical point of overcoming the random motion and are now collapsing under its own gravitation into an increasingly dense superstructure. Figure 03-09a is a computer simulation of the growth of large scale structure as matter is accreted along the filaments. Each square represents a step in the evolution of the universe. The sequence commences at redshift 10.0, less than 500 million years after the Big Bang, and terminates at redshift 0 corresponding to the current epoch. However, superclusters are recognizable by observation only up to a distance of about 8x109 lys at z ~ 1; and we cannot see the Virgo supercluster (within ~ 200 million lys) in which we are living (Figure 03-09b). |