Quantum Spin Experiment Tests Gravity's Influence.

Researchers from the University of Science and Technology of China have conducted an experiment to search for an interaction between a particle's intrinsic quantum spin and Earth's gravitational field. Although no evidence for this interaction was found, the search yielded strong constraints that have implications for the existence of hypothetical forces of nature and for the origin of the matter-antimatter asymmetry of the Universe. The USTC experiment is mainly sensitive to the strength with which gravity couples to neutron spins, and the team's measurements establish the most stringent constraint on any coupling of intrinsic spin to gravity.