Wireless power transmission is moving from lab curiosity toward real-world utility, at least if the Defense Advanced Research Projects Agency's latest test is any indication. DARPA says the Persistent Optical Wireless Energy Relay (POWER) team program managed to transmit more than 800 watts of power from a laser emitter to a receiver located 5.3 miles (8.6 kilometers) away during a 30-second transmission. To celebrate the achievement, POWER used some of the transferred energy to make popcorn - a...