From: helbig@asclothestro.multivax.de   
      
   In article <4e3fc804-15b4-edeb-2880-0fae88f6e50a@comcast.net>, Mike   
   Fontenot  writes:   
      
   > On 3/7/22 2:09 PM, Mike Fontenot wrote:   
   >   
   >> But with a UNIFORM and constant gravitational field (absolutely parallel   
   >> field lines, and no variation in field strength), the equivalence   
   >> principle says this is equivalent to two test bodies undergoing the same   
   >> constant acceleration, with no gravitational field present.   
   >>   
   >> [[Mod. note --   
   >> Note also that in the context of general relativity, one needs to be   
   >> careful in invoking the equivalence principle for a *uniform* *constant*   
   >> gravitational field.  The problem is that such a field is the result of   
   >> (i.e., implies the presence of) an infinite mass plane,   
   >   
   > True,   
      
   Which also implies that it very probably doesn't exist; it certainly   
   doesn't exist in our Universe.   
      
   >> which means that   
   >> spacetime is *not* asymptotically flat.  That has a number of "interesting"   
   >> consequences...   
   >> -- jt]]   
   >>   
   >   
   > Can you elaborate on that?  Why does that imply that spacetime "is not   
   > asymptotically flat"?  And what exactly does "asymptotically flat" mean?   
      
   Basically, it means that if you are far enough away from masses,   
   spacetime is Minkowski space, i.e. space itself is Euclidean and the   
   fourth dimension is time multiplied by the speed of light and there is   
   no curvature (neither of space nor of spacetime).  Obviously, if there   
   is an infinite mass, one could never get "far enough" away from it.   
      
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