An apology to Androcles
in [Relativity]
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From: Edward Green on 13 Aug 2010 16:31 On Aug 11, 3:07 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: <...> > A rod pushed in front of a rocket will *initially* compress to > a length that is less than its equilibrium length, but then will > expand to eventually settle down to its equilibrium length. > > A rod pulled behind a rocket will *initially* stretch to a length > that is greater than its equilibrium length, but will then contract > to its equilibrium length. Well, obviously assuming no permanent plastic deformation, and also that the acceleration eventually stops. Although by "equilibrium length" I suppose we could also mean the new equilibrium length if the rod suffered permanent deformation.
From: Androcles on 13 Aug 2010 16:37
"Edward Green" <spamspamspam3(a)netzero.com> wrote in message news:b544b23f-b69a-42be-b997-fb48b5011ba8(a)l14g2000yql.googlegroups.com... | On Aug 12, 3:33 pm, harald <h...(a)swissonline.ch> wrote: | > On Aug 12, 3:37 pm, stevendaryl3...(a)yahoo.com (Daryl McCullough) | > wrote: | <...> | > Nice, everything you write looks quite perfect - until the logical | > glitch right at the end. | > | > I would improve it as follows (which is certainly not by chance closer | > to the way Einstein put it!): | > | > "If the laws of physics possess a certain kind of symmetry, then there | > is nothing special about that frame for the laws of physics." | > | > A minor change? Not really! Compare: | > | > "If a picture is a perfect copy of a painting, then there is nothing | > special about the painting." | > | > with: | > | > "If a picture is a perfect copy of a painting, then there is nothing | > special about the painting for imaging purposes." | | I don't really understand your... watchamacallit: simile? analogy? | | Anyway, even if there is nothing special about a certain frame, we can | always construct a complete description of events from that frame, | which can be a very powerful point of view, I think. As Bell would | have said: in eliminating certain modes of thinking which were wrong, | we also forgot some which are right. | ============================================ http://www.youtube.com/watch?v=tAIZRVeGJd4 Watch from 4:41 minutes into the sequence and tell me all frames are the same. |