Made by the nine-year-old helmet company Xenith, the X2 replaces foam padding with an array of air-filled cylinders that compress upon impact by releasing air through tiny holes. The harder the hit, the stiffer the response. Such adaptive cushioning can protect against both lower-level and higher-level forces but still does little to address rotation.
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.