Science Ahead

With a measly 'stroke to motion' conversion rate of 3 percent, humans are certainly the least equipped for underwater swimming. Sure as eggs, they need a booster or 'powered swimming' - the stuff of James Bond movies. With a glider-like device, DARPA.

Northrop Grumman is developing an unmanned, shape-changing supersonic plane concept that could not only loiter outside enemy territory for more than 12 hours but can also hurtle toward a target with a speed faster than sound, on command. And level it...