From: tjroberts137@sbcglobal.net   
      
   On 8/9/21 12:57 PM, Eric Flesch wrote:   
   > The problem with sub-c neutrinos is that they would all need to be   
   > accelerated to near-c speed by their emitters.   
      
   That's no different from any other decay or emission, in which the   
   daughter particles emerge at high speed, often approaching or equal to   
   c. But they are not "accelerated" to such speeds, they are created with   
   such speeds -- a common aspect of elementary particle interactions.   
      
   > Why so uniform?  You'd expect to find some at slower speeds.   
      
   The upper bound on the mass of the electron neutrino is 1.1 eV. The   
   lowest-energy neutrinos detected are far above that energy, so one would   
   NOT expect to detect such neutrinos with speeds measurably slower than   
   c. Ditto for muon neutrinos, for which the upper bound on mass is 0.19 MeV.   
      
   As the moderator says, lower-energy neutrinos have smaller interaction   
   cross-sections, and even high-energy neutrinos have very tiny ones. So   
   it is very difficult to detect them. On earth there are billions of   
   low-energy neutrinos per cubic meter, but we don't notice them at all,   
   except for the largest and most sensitive neutrino detectors (which   
   are unable to measure their speed).   
      
   Tom Roberts   
      
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