Steering atoms toward better navigation, physicists test Newton and Einstein along the way

Stanford physicist Mark Kasevich has adapted the technology in today's airplane navigation systems to work with atoms so cold that they almost stand still. At temperatures scarcely above absolute zero, atoms no longer behave as particles but rather as de Broglie waves, named for the theorist who originally posited that all matter behaves as both a light wave and as a particle. These waves can be configured to add or subtract, or interfere, with one another in an interferometer-an instrument that is used on airplanes to measure very small changes in rotation.