For the first time researchers have found evidence neutrinos have mass, a key finding that could explain where all that dark matter we haven’t been able to find is hiding:
In the new experiment, physicists captured a muon neutrino in the process of transforming into a tau neutrino. Researchers had strongly believed that such transformations occur because they have been able to observe the disappearance of muon neutrinos in a variety of experiments.
But the research announced Monday marks the first time that the appearance of a tau neutrino has been directly observed. …
Astrophysicists have inferred the existence of dark matter from their observations that the total amount of visible matter is insufficient to account for gravitational effects. It is estimated that dark matter accounts for 80% of the mass of the universe and visible matter only 20%.
The new finding is important because in the theories now used to explain the behavior of fundamental particles, called the Standard Model, neutrinos have no mass. But if they have no mass, they cannot oscillate between muon and tau forms. The fact that they do oscillate indicates that they have mass and that the fundamentals of the Standard Model need some reworking, at the very least.