From: tjoberts137@sbcglobal.net   
      
   On 5/13/24 1:58 AM, Luigi Fortunati wrote:   
   > When there is an experiment that proves Einstein right, the whole   
   > world is ready to praise him and his theories (and rightly so).   
   > However, it is not right that, when an experiment proves Einstein   
   > wrong, no one admits it and no one talks about it.   
      
   This last is just plain wrong. Any REAL experiment that refuted either   
   SR or GR would be GREAT NEWS and the experimenters would win praise and   
   accolades. But they must be real experiments within the domain of   
   applicability of the theory, and statistically inconsistent with its   
   predictions. To date no such experiments have ever been published --   
   your allegations here are just drivel: they are not real experiments,   
   and they indicate that YOU do not understand General Relativity, because   
   your claims are based upon a PUN on the word "acceleration".   
      
   > Einstein says that bodies in free fall are at rest and that the man   
   > inside the falling elevator experiences no forces or accelerations.   
      
   No. This is A LOT more subtle. So much so that this claim is just plain   
   wrong. You MUST learn about the actual theory before you can have any   
   hope of refuting it. All you have done here is shown that your personal   
   misconceptions are inconsistent with each other -- useless.   
      
   > [...] two massive bodies (which fall gravitationally and freely   
   > towards each other) *accelerate* both in the reference of one and   
   > both in that of the other.   
      
   Sure. This does not refute GR, because of your confusion between   
   coordinate acceleration and proper acceleration. These two bodies have   
   zero proper acceleration, and nonzero coordinate acceleration. The   
   equations (and predictions) of GR are necessarily coordinate   
   independent, and basically say nothing at all about coordinate   
   acceleration, because one can choose any coordinate system. In the   
   absence of forces on an object, GR predicts it has zero proper   
   acceleration (while its coordinate acceleration can be anything,   
   depending on the coordinates used). In GR, gravitation is an aspect of   
   the geometry of spacetime, not a force.   
      
        [Note to experts: there are missing caveats and conditions   
         here, but they are irrelevant to Fortunati's basic problem.]   
      
   > [... other claims showing further ignorance of GR]   
      
   As I have repeatedly told you, you MUST get a good textbook and STUDY   
   physics. Start with classical mechanics, and be sure you have mastered   
   it before attempting GR. Better would be taking physics courses at a   
   local college or university. Posting dubious claims in a newsgroup is a   
   TERRIBLE approach and will never teach you much physics. There are no   
   shortcuts.   
      
   > If body A falls towards body B, body B also falls towards body A. If   
   > body A accelerates towards body B, body B also accelerates towards   
   > body A. And these two mutual accelerations never disappear, whatever   
   > the reference from which we measure them! They are real accelerations   
   > generated by real forces.   
      
   Not in GR. GO STUDY and stop wasting your time on nonsense. You do NOT   
   have enough knowledge to just "think this through" on your own.   
      
   Tom Roberts   
      
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