From: wugi@brol.invalid   
      
   Op 7/09/2023 om 7:52 schreef Luigi Fortunati:   
   > wugi il 05/09/2023 09:21:30 ha scritto:   
   >> ...   
   > Richard Livingston il 05/09/2023 06:01:20 ha scritto:   
   >> ...   
   >   
   > We obviously live in different worlds.   
   >   
   > In my world, a body that contracts, compresses.   
   >   
   > And a rigid body doesn't become flexible just because it's in motion.   
      
   You live in a still Newtonian world, not understanding relativity of   
   simultaneity and the length contraction and time dilation properties   
   that go with it. Absolute rigidity implies absolute simultaneity and   
   time (for a measurement to be "absolute"), which don't exist in SRT.   
      
   And as Mod. said, what with all those different observers who observe   
   all those different length contractions? Which "absolute" length   
   contraction is disturbing your rigidity considerations?   
      
      
   > [[Mod. note --   
   > You are taking it for granted that the body does in fact contract   
   > or become flexible.  But those observations are made by an observer   
   > who is not at rest with respect to the body!   
   >   
   > If observer A (at rest with body X) observes X to be uncontracted,   
   > and observer B1 (moving at velocity v1 with respect to X) observes X   
   > to be contracted by some amount R1, and observer B2 (moving at some   
   > different velocity v2 with respect to X) observes X to be contracted   
   > by some different amount R2, what should we infer?  More generally,   
   > there are infinitely many possible observers B1, B2, B3, B4, ...,   
   > each of who will observe a different contraction of X.   
   >   
   > In special relativity, the answer is that we privilege observations   
   > made in the rest frame of the body being observed (in this case X).   
   >   
   > To put it another way, can you explain why you think it's paradoxical   
   > that observer B1 observes something different from observer A?   
   > -- jt]]   
      
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