These dense, slender strands of dark matter and galaxies connect the cosmic web, channeling matter toward galaxy clusters at each strand’s end (SN: 7/5/12). “We don’t have a full theory of how every galaxy comes to rotate, or every filament comes to rotate,” says Mark Neyrinck, cosmologist at University of the Basque Country in Bilbao, Spain. A computer simulation shows how a cosmic filament twists galaxies and dark matter into a strand of the cosmic web.