Scientists have discovered a new way to investigate the structure of protons using neutrinos, known as ‘ghost particles. While the new technique does not produce a sharper image than the old technique, McFarland says, it may give scientists new information about how neutrinos and protons interact—information they can currently only infer using theoretical calculations or a combination of theory and other measurements. “We need detailed information about protons to answer questions like which neutrinos have more mass than others and whether or not there are differences between neutrinos and their anti-matter partners,” Cai says