Neutrinos: They have no electric charge, pass through matter like a ghost and are so light they were initially thought to have zero mass. These are just some of the traits that make them so difficult to detect. Research on neutrinos requires massive underground observatories far from potential confo unders that drown out their weak signals. One of the largest in the world, located 1,000 meters (3,281 feet) underground in Gifu Prefecture, Japan, is called Super-Kamiokande. ...read more read less