PAllen's latest activity
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PPAllen replied to the thread I Euclidean geometry and gravity.I will make a self correction which implies we were both right/wrong in a sense. Again, I think the correct analog to a well understood...
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PPAllen replied to the thread I Euclidean geometry and gravity.In my view, this is not a sensible approach. What you have is a collection of independent rockets, not a body. In a body, in any normal...
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PPAllen replied to the thread I Euclidean geometry and gravity.Another thought on this is to emphasize that spatial geometry is simply a choice of simultaneity, with the same conventionality as in...
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PPAllen replied to the thread I Euclidean geometry and gravity.I agree this is the fundamental question. I lean in the same direction as you (@pervect ). [This would mean that Herglotz-Noether...
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PPAllen replied to the thread I Euclidean geometry and gravity.What I know and don't know as of this point in the discussion: 1) You can have rigid body (congruence) of parametrized by varying r...
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PPAllen replied to the thread I Euclidean geometry and gravity.I think it is important to recall points made in some other threads about the limitations imposed by Herglotz-Noether : they apply to a...
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PPAllen replied to the thread I Euclidean geometry and gravity.But the real content of the theorem is what cases are possible. I have not been able to access discussions of this. The only things I...
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PPAllen replied to the thread I Euclidean geometry and gravity.The only such stresses on a rigid object, whatever its history, are those of tidal gravity.
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PPAllen replied to the thread I Euclidean geometry and gravity.Yes.
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PPAllen replied to the thread I Euclidean geometry and gravity.I am going to take some time responding to the rest of your post, but on this want to point out that the stationary congruence (constant...
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PPAllen replied to the thread I Euclidean geometry and gravity.So far as I know, Herglotz-Noether is purely a theorem of SR. The case described would definitely be a possible rigid motion in SR - you...
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PPAllen replied to the thread I Euclidean geometry and gravity.Thinking more about this, I come back to believing that for physics of materials, the only valid approach is in terms of kinematic...
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PPAllen replied to the thread I Euclidean geometry and gravity.I don't know that that is definitive. See my longer post on this, coming soon.
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PPAllen replied to the thread I Euclidean geometry and gravity.I am not quite sure how much of embedding theory corresponds to physics in pseudo-riemannian geometry, but I think it is worth pointing...
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PPAllen replied to the thread I Euclidean geometry and gravity.Claim: There is no difficulty defining a congruence of world lines representing a piece of paper far from a BH, that then has each...