Number 45 (Story #2), August 30, 1991 by Phillip F. Schewe and Ben Stein LIMITS ON THE ELECTRON ANTINEUTRINO MASS have been further tightened by observations of the beta decay of molecular tritium by scientists at Los Alamos National Lab (John Wilkerson, 505-667-9429). In this latest update on the long-running effort to determine whether neutrinos have a nonzero mass---an issue with implications for cosmology---the Los Alamos scientists have established an upper limit of 9.3 eV for the mass of the electron antineutrino, markedly different from the mass range of 17-40 eV reported by a team at the Institute of Theoretical and Experimental Physics (ITEP) in Moscow. (Upcoming article in Physical Review Letters.)