From: jonathan@iron.astro.indiana.edu   
      
   In article ,   
   Sabbir Rahman wrote (addressing Gregor Scholten)   
   > I replied earlier to this, though the reply has yet to appear. Much   
   > of the confusion that arose was due to our using different definitions   
   > of "Schwarzschild interior metric". I was talking about the metric   
   > associated with the vacuum Schwarzschild interior solution, NOT the   
   > Schwarzschild interior metric that you provided a link to.   
      
   In that same article, I wrote in a moderator's note   
   > [[Mod. note -- There is indeed confusion.  Perhaps you could be   
   > clearer what you mean by the phrase "vacuum Schwarzschild interior"   
   > solution?  I know of two solutions to the Einstein equations which   
   > are commonly ascribed to Schwarzschild:   
   > (a) the Schwarzschild black hole solution (which isn't "interior",   
   >     but rather extends out to r=infinity)   
   By "interior" here I meant "interior to some *other* solution.   
      
   > (b) the Schwarzschild star (which isn't vacuum, and whose matter   
   >     content isn't dust)   
   > and neither of them really fit that phrase.   
   > -- jt]]   
      
   On reading Sabbir's other posting later in this thread, I think it's   
   now fairly clear that he is referring to solution (a), and that he is   
   using "interior" in the sense of "inside r=2M" or "inside the event   
   horizon".   
      
   That's not the standard usage in general relativity, where "interior"   
   usually means "inside some *other* metric"; it's this latter sense that   
   I meant when I said that (a) isn't "interior".   
      
   The standard usage is to say that solution (a) applies for all $r > 0$,   
   including both inside & outside the event horizon, and call this solution   
   it "the Schwarzschild solution" (without the qualifier "interior").  If   
   the solution (a) applies everywhere, i.e., if the whole spacetime is   
   vacuum, it's usually called "Schwarzschild spacetime".   
      
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   -- "Jonathan Thornburg [remove -animal to reply]"    
      Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA   
      currently visiting Max-Plack-Institute fuer Gravitationsphysik   
                         (Albert-Einstein-Institut), Potsdam-Golm, Germany   
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