From: tjroberts137@sbcglobal.net   
      
   On 7/2/18 12:07 AM, Jay R. Yablon wrote:   
   > Photons are massless while neutrinos do have a very tiny mass. So neutrinos   
   > will travel at a  rapid but still subluminal velocity.  So how after such a   
   > long journey can they arrive at nearly the same time? Unless the word   
   > \_nearly_/ was used to indicate an accounting for the small mass which would   
   > slightly delay their arrival?   
      
   The observed neutrinos from SN1987A had energies up to 40 MeV [%]. The Particle   
   Data Group gives the upper limit on the neutrino mass of 2 eV [$]. For a mass   
   of   
   2 eV, 40 MeV gives beta ~ 0.999999999999999 [#]; 1-beta ~ 1E-15. After a trip   
   of   
   160,000 years (5E12 seconds) [%], this implies an upper limit on the time   
   difference between massless photons and neutrinos of a few milliseconds, which   
   is completely unobservable.   
      
   	[%] See Mike Longo's papers, cited earlier in this thread.   
   	[$] Neutrino oscillations imply much smaller mass differences.   
   	[#] Excel is right at the limit of its accuracy here.   
      
   Note that in 1987, neutrinos were thought to be massless; observations of   
   neutrino oscillation were more than a decade in the future.   
      
   Tom Roberts   
      
   --- SoupGate-Win32 v1.05   
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