Have Massive Cosmological Neutrinos Already Been Detected?

The possibility is investigated that the decay of massive cosmological neutrinos may have produced a spectral signature which has already been detected in observations of the ultraviolet background radiation. Various implications are discussed including a possible implied neutrino mass of 13.8-14.8 eV. A lower limit is also placed on the lifetime of heavy neutrinos ${\nu }_H$ with respect to the decay ${\nu }_H\to {\nu }_L+\gamma$ based on the cosmic uv observations.