You've almost certainly seen a pressure gauge somewhere: on an air compressor, a steam boiler or perhaps an automotive vacuum gauge. Have you thought much about how that gauge works? Magic? Elves? We'll rip one open to find out.
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.