This universe full of neutrinos all the time, Neutrinos everywhere, nearly undetectable, flitting through ordinary matter. We hardly know something about them, not even how complex they are. But the study shows that neutrinos have the potential to alter the form of the entire universe. And since they have that power, we can use the shape of the world to weigh them as a team of physicists has now carried out.
Because of physics, the behaviors of the tiny particles change the behaviors of whole galaxies and other giant celestial structures. And if we want to describe the behavior of the universe, we must take into account the properties of its tiniest components. In a new paper, which will be revealed in a forthcoming issue of the journal Physical Review Letters, researchers used that fact to again-calculate the mass of the lightest neutrino (there are three neutrino masses) from precise measurements of the large-scale structure of the universe.
They took data about the movements of roughly 1.1 million galaxies from the Baryon Oscillation Spectroscopic Survey, stirred it up with other cosmological information and outcomes from much smaller-scale neutrino experiments on Earth, and fed all that data into a supercomputer. The result didn’t supply a set quantity for the mass of the lightest sort of neutrino, but it did narrow it down. That species of neutrino has a mass no larger than 0.086 electron volts (eV), or about six million times less than the mass of a single electron.
Confusingly, the three mass species of neutrino do not line up with the three flavors of neutrino, electron, muon, and tau. Every character of the neutrino is made up of a quantum combination of the three mass species. So a sure tau neutrino has a few mass species 1 in it, a little bit of species 2 and a little bit of species 3. Those different mass species permit the neutrinos to jump back and forth between flavors, as a 1998 discovery (which won the Nobel Prize in physics) confirmed.
Physicists might never correctly pinpoint the masses of the three neutrino species, but they can keep getting closer. The mass will keep getting narrowed down as experiments on Earth and measurements in space improve, the authors wrote. And the better physicists can measure these tiny, omnipresent elements of our universe; the better physics will be capable of explaining how the whole thing fits together.