Invisible, cold dark matter plays a major role in the evolution of galaxies, according to modern cosmological theory. The most advanced simulations of cosmic evolution show stringy tendrils of mass — dark matter — connecting giant clusters of galaxies via a vast cosmic web. Now for the first time, astronomers have been able to detect one of these filaments, sussing out its location by watching it warp light.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.