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What Einstein meant when he termed something a 'mollusc'

  1. Mar 31, 2010 #1
    I have been reading over the two theories, and cannot figure out what Einstein meant when he termed something a 'mollusc'. Can someone please explain?
  2. jcsd
  3. Mar 31, 2010 #2


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    Re: Molluscs?

    I think you're talking about this:
    He's just talking about arbitrary noninertial coordinate systems, maybe he used the word "mollusk" to suggest a curvy shape like the body of an octopus or a slug. Take a look at http://www.aei.mpg.de/einsteinOnline/en/spotlights/background_independence/index.html [Broken], particularly the part where they talk about "diffeomorphism invariance", for more on the idea that the equations of GR work in arbitrary coordinate systems...the last animated diagram on the page shows some rather "mollusk-like" curvilinear coordinate systems.
    Last edited by a moderator: May 4, 2017
  4. Apr 1, 2010 #3
    Re: Molluscs?

    thanks for the help :)
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