Inventor J.H. Purves imagined that droves of his electrically-driven unicycle would roll like tumbleweeds alongside more conventional vehicles. To steer the "dynasphere," drivers would sit in an enclosed cabin that would remain still while the wheel spun around it.
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.