Your smartphone always knows where you are because it communicates with GPS satellites in space. But one day, perhaps, it won't need that anymore. Instead, it may figure out your location using the effects of gravity on atoms right here on Earth, making it able to locate you even when you're underwater, indoors, or underground.

The U.K.'s Ministry of Defense is investing "millions of pounds" in quantum location technology, the Financial Times reports. Such a "quantum compass" would be 1,000 times more accurate than any systems today and much more difficult to hack than GPS. Scientists working on the project told the Financial Times they expect to have a prototype in three to five years. If successful, the compass' first applications would be in the military, including in super-accurate missiles, the New Scientist reports. Eventually, the technology could make its way into the civilian world.