Precision instrument bolsters efforts to find elusive dark energy

Dark energy — a mysterious force pushing the universe apart at an ever-increasing rate — was discovered 26 years ago, and ever since, scientists have been searching for a new and exotic particle causing the expansion. Physicists combined an optical lattice with an atom interferometer to hold atoms in place for up to 70 seconds — a record for an atom interferometer — allowing them to more precisely test for deviations from the accepted theory of gravity that could be caused by dark energy particles such as chameleons or symmetrons. Though they detected no anomalies, they’re improving the experiment to perform more sensitive tests of gravity, including whether gravity is quantized.