It's easy to take for granted just how insanely close some Olympic races are, and how much the minutiae of it all can matter. The perfect example is the traditional starting gun. Seems easy. You pull a trigger and the race starts. Boom. What people don't consider: When a conventional gun goes off, the sound travels to the ears of the closest runner a fraction of a second sooner than the others.
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.