Beneath the city of Jiangmen lies a large research infrastructure that's specifically used for the study of neutrinos. Neutrinos are the oldest and most primitive elementary particles that have existed since the beginning of the universe. Understanding neutrinos opens the door to understanding the universe and existing matter in the world. CGTN reporter Liu Jiaxin paid a visit to this large detector, Jiangmen Underground Neutrino Observatory, before it's officially put into operation.