From: fortunati.luigi@gmail.com   
      
   Tom Roberts giovedì 21/09/2017 alle ore 15:53:32 ha scritto:   
   >> Newton claims that gravity is a force, Einstein denies it: for him it is not   
   >> a force (it is something else).   
   >   
   > Yes, in GR gravity is an aspect of the geometry of spacetime -- it can   
   > masquerade as a fictitious "force", like "centrifugal and Coriolis force",   
   > due to choice of coordinates.   
      
   How can a different choice of coordinates have some influence on the   
   "measurement" of a force?   
      
   Force is the one exercised in its "point of application" and is unique.   
      
   If the bleacher exerts a force of 600 N on the scaffolding (and vice   
   versa), that force is always equal to 600 N for everyone!   
      
   Otherwise tell me in what other reference system the bleacher could   
   exert on the scaffold a force other than 600 N or even nothing.   
      
   --   
   Credere e' piu' facile che pensare   
   Believing is easier than thinking   
   Luigi Fortunati   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)