"Don't drink the water," Americans traveling overseas are often admonished, "it'll make you sick."
Yet the natives drink the same water with impunity. What's going on? Do foreign visitors to the United States have the same problem?
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.