Novel particle beam could challenge Einstein's theory of gravity

Does gravity act equally on all particles in the universe, or are there differences between ordinary and exotic matter? Physics professor Anna Soter and her team at ETH Zurich and the Paul Scherrer Institute (PSI) in Villigen are investigating this question. "We have taken an important step toward carrying out an exciting experiment on this topic," says Soter. "We want to measure the gravitational interaction of the muon."