From: tjroberts137@sbcglobal.net   
      
   (Responding to the moderator)   
   > 	[Digression:   
   > 	I suspect, but have not worked out in detail, that for   
   > 	a flat spacetime it is possible to have twin paradox if   
   > 	the spacetime is multiply connected.  In particular,   
   > 	consider paths going on opposite sides of a "cone"   
   > 	singularity, one where the circumnavigation angle is   
   > 	different from 2*pi radians.]   
   > -- jt]]   
      
   A simpler, more direct case: consider a flat (2+1)-D spacetime with   
   topology (SxR)xR -- a spatial cylinder. One twin moves along the   
   cylinder's axis, and the other goes around. The latter will have less   
   elapsed proper time between meetings. Both twins have zero proper   
   acceleration. In general, the inertial twin with the lower winding   
   number between meetings has the larger elapsed proper time.   
      
   Tom Roberts   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)