From: fortunati.luigi@gmail.com   
      
   Jonathan Thornburg [remove -color to reply] il 03/01/2025 23:18:17 ha   
   scritto:   
   > Let's analyze a somewhat more general system:  Suppose we have a pair   
   > of masses A and B, and consider the effects of adding a mass C at either   
   > position #1 or position #2.   
   > 	[Luigi's original question had position #1 = position   
   > 	of A, position #2 = position of B, mass A = 1000, mass   
   > 	B = 1, and mass C = 1, but I find it useful to consider   
   > 	the more generic case.]   
   >   
   > A+B+C1 and A+B+C2 are *physically different* systems (going from one to   
   > the other involves moving the mass C from position #1 to position #2).   
   > So why should we expect any of the following Newtonian gravitational   
   > effects to be the same between these two *physically different* systems:   
   > * Newtonian gravitational potential U at some test point X   
   > * Newtonian gravitational acceleration "little-g" at some test point X   
   >   (= - gradient of U)   
   > * force between A+C1 and B versus force between A and B+C2   
   >   
   > In fact, it's easy to see that all three of these "effects" differ...  as   
   > we should expect, because (again) we're comparing *physically different*   
   > systems.   
      
   It's true, you convinced me because your reasoning is completely   
   logical and shareable: we expect anything except that two physically   
   different systems give the same effects.   
      
   But then, why do two extraordinarily different systems like the Earth's   
   mass (6*10^24kg) generate the force of 90kg-weight on my body (mass   
   90kg) and my body generates the *same* opposing force of -90kg-weight   
   on the Earth?   
      
   Luigi Fortunati   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)