Hi all.  A massive spin one particle can have spin 1,0, or -1 in any   
   spatial direction.  But for the massless photon spin in the direction of   
   motion must be 1 or -1.  What is the easiest way to explain why 0 is   
   excluded?  I am not asking for a proof, which can be found in texts on   
   QFT.  But rather I would like a nice simple concept, if there is one,   
   that makes it easy to understand.  So what is the simplest way to   
   explain the gist of the matter?   
      
   Mike   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)