GPS can be useful when you're trying to navigate to that hot new bar -- as long as your travels don't take you somewhere its signal can't reach. A new so-called quantum positioning system could pick things up when satellites fail, and help guide your way using super-cooled atoms. Aside from better directions, the solution might even make travel safer. While existing accelerometer-based systems can track location underwater within a kilometer, quantum positioning can do it within a meter, making it 1,000 times more accurate. With submarines, that could be the difference between staying safe and drifting into hostile waters.