The Bolshoi simulation reveals a cosmic web of dark matter that underlies the large-scale structure of the Universe and, through its gravitational effects on ordinary matter, drives the formation of galaxies and galaxy clusters. Images show the simulation's final time-step, representing the present epoch of the universe, at different scales. The image above is a slice of the entire simulation, 1 billion light-years across and about 30 million light-years thick. Credit: Images by Stefan Gottlober (AIP)