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Nobody quite understands why there is such excitement about the succession of superconducting materials with ever-higher transition temperature. But the phenomenon may be simpler than it seems.
The historic detection by the Kamiokande-II collaboration1 and the IMB collaboration2 of neutrinos from the Large Magellanic Cloud (LMC) supernova provides the first opportunity to determine the mass, , of the electron neutrino from astronomical observations. Here we show that , is less than 11 eV, provided only that propagation effects have not conspired to sharpen, by more than a factor of two the narrow pulse-width of neutrinos, observed by the Kamiokande-II collaboration from the LMC supernova. This result improves on the laboratory limit on and confirms the view that electron neutrinos do not constitute the major component of the matter density of the Universe.