Viewpoint: Yes, the Japanese-U.S. research team called the Super-Kamiokande Collaboration announced experiment results in 1998 that proved that neutrinos do indeed have mass.

Viewpoint: No, the experiments of earlier twentieth-century scientists repeatedly indicated that neutrinos did not have mass.

In 1931 Wolfgang Pauli first predicted the existence of a subatomic particle that Enrico Fermi would later name the neutrino. The neutrino must exist, Pauli reasoned, because otherwise the atomic process known as beta decay would violate the physical laws of conservation of energy and conservation of angular momentum. Neutrinos had never been detected, so Pauli concluded that they didn't interact with most other particles or forces. This implied they were extremely small particles with no charge or mass.

The only force that noticeably affects neutrinos is the "weak" force, a subatomic force that is not as strong as the...