Physicists have established the first estimate of the mass of the lightest of the elementary particles called neutrinos by bringing two types of data together. They established the limits by combining data from particle-physics experiments and surveys of the cosmos.
Neutrinos are the least massive elementary particles known to us, with the exception of the supposed completely massless particles like the photon. Physicists are aware that neutrinos come in three possible masses, but directly measuring them has been a challenge till now. Studies that analyze the large-scale structure of the Universe covering the distribution of galaxies across space and the residual radiation from the Big Bang have indirectly provided information on the combined mass of the three neutrino sizes. In the meantime, particle-physics experiments on Earth have also provided partial evidence on the relative sizes of the three masses.
Arthur Loureiro of University College London and his team have now churned combined data from both types of studies through a supercomputer for the first time. Their results reveal that the lightest of the three types of neutrinos, has a mass of at most 0.086 electronvolts, implying that it is at least 6 million times lighter than an electron.
As the accuracy of cosmology and particle-physics data improves, this technique will also provide increasingly precise limits on neutrino masses, the authors noted in their research.