For decades, physicists have known that neutrinos have mass, but they have not been able to say exactly how much. The particles are notoriously difficult to study, and the scale of their mass has remained one of the field's most stubborn puzzles.
Now a gigantic experiment in China is poised to change that. By making a precise measurement, it could finally answer the long-standing question of how much neutrinos weigh. The result would not just fill in a number—it would have deep implications for the Standard Model of particle physics and for cosmology.
The experiment is described as being on the verge of delivering data that could settle the mystery. If successful, it would mark a major step forward in our understanding of these elusive particles and the fundamental laws that govern the universe.