Two neutrinos arrive at Earth from SN 1987A. The observed energies of the neutrinos measured on Earth ranged from 8 - 41 MeV. If the distance L = 168000 light-years, and the observed spread in arrival times of the neutrinos was 12 seconds, what is the upper bound on the neutrino mass placed by SN 1987A? Give your answer in eV/c2.
delta(t) = (L/c)[1+(m2c4/2E2)]
(Answer should probably be around 20 eV/c2 )