ETH Zurich and PSI produce a cold muonium beam to test gravity

Image: Markus Fischer / Paul Scherrer Institute · ethz.ch Researchers at ETH Zurich and the Paul Scherrer Institute are artificially producing an intense, cold beam of muonium, an exotic atom containing a second-generation antiparticle, to test a fundamental prediction of Einstein’s theory of gravity. The team aims to measure whether Earth’s gravitational pull acts on muonium in the same way it does on ordinary matter, a principle known as the universality of free fall. “We have taken an important step towards carrying out an exciting experiment on this topic,” says Anna Soter, professor of physics at ETH Zurich; “We want to measure the gravitational interaction of the muon.” A difference in how these exotic atoms fall could indicate the existence of a fifth fundamental force. The creation of a superthermal muonium beam at ETH Zurich represents an advancement in precision measurement, enabling researchers to probe the gravitational interaction…