Where were we when this was taken? Do you remember, dear?
Tired of trying to identify landmarks in your endless folders of travel photos? Google's image recognition engine could help. Just upload the mystery image to an online album, point the engine at it, and zap -- turns out it was the Acropolis, in Athens, Greece.
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.