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This is an old revision of this page, as edited by Delaszk (talk | contribs) at 01:32, 27 November 2008. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

de Sitter relativity

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    De Sitter relativity (edit | talk | history | protect | delete | links | watch | logs | views) (delete) – (View log)

    This doesn't appear to be notable. Chasing citations from the papers/preprints mentioned in the references, I found no independent critical review of this work. Most of the citations were from other papers by the same group of de Sitter relativity proponents. The few exceptions mentioned the papers only in passing in a survey of related work, or (in one case) in support of a true but trivial statement about the infinite-curvature limit of de Sitter space which isn't central to the papers' main claims.

    I should probably add that the papers appear to me to be nonsense; the authors don't seem to understand special relativity or cosmology. I'd expect any well-known cosmologist who did review the papers to reach the same conclusion. This puts Wikipedia in an impossible situation if the article is kept—pointing out flaws in the paper would be original research or synthesis, but not pointing them out (as our article currently doesn't) creates the impression of a scientific consensus that doesn't exist. I think that the notability requirement exists to protect us from just this kind of situation, and so the article ought to be deleted as non-notable. -- BenRG (talk) 23:17, 23 November 2008 (UTC)[reply]

    :Unfortunately most of those Google hits are about earlier work on de Sitter spacetime and are not about the modifications to special relativity that are proposed here. Delaszk (talk) 13:56, 24 November 2008 (UTC) [reply]

    Actually a lot of those hits are ok, I was thinking about a search I had made with the words de,sitter,relativity not joined together with dashes. Delaszk (talk) 23:03, 24 November 2008 (UTC)[reply]
    • Comment I agree that the theory is basically nonsensical in that anybody ever having done FRW cosmology and studied the deSitter solution knows that this doesn't really require any modification to GR. But unfortunately, that is no reason for deletion.
    However, the theory has little to no notability which might be reason for deletion.
    If the article is kept, it needs a major rework, because currently it has major NPOV issues; it reads like an infomercial for the theory. (TimothyRias (talk) 07:11, 24 November 2008 (UTC))[reply]
    In ordinary SR/GR you don't require these changes, however if you make the modifications to SR that are proposed here then there are corresponding modifications to GR to be made. Delaszk (talk) 13:54, 24 November 2008 (UTC)[reply]

    :*Keep I've made some changes to the article to address these issues. Also there are still more references, yet to be added, about de Sitter relativity in the limit as v<<c. Delaszk (talk) 15:13, 24 November 2008 (UTC)[reply]

    Still a delete from me.Headbomb {ταλκκοντριβς – WP Physics} 23:18, 24 November 2008 (UTC)[reply]
    Your changes aren't nearly enough. De Sitter relativity isn't just new or untested, it doesn't even make sense as a theory. "Modifying general relativity to make it locally de Sitter instead of locally [Minkowski]" doesn't mean anything on the face of it. De Sitter space is the Lorentzian analogue of a sphere, so it's like saying that one should modify surfaces to be locally spherical instead of locally flat. Most surfaces are neither. The use of flat tangent spaces in general relativity doesn't involve any assumption about the manifold except that it's differentiable. Maybe one could study manifolds using tangent spheres instead, but it would be the same theory (since the manifolds are the same), just expressed in less convenient language. The only nontrivial meaning I can think of for "locally de Sitter manifold" would be a manifold whose curvature at every point was purely scalar, but that can't be what they mean; it wouldn't reproduce the most basic features of Newtonian gravity.
    Their motivation for using de Sitter space in the first place—that its isometries preserve an invariant length—also doesn't make sense. The isometries preserve the radius of curvature, just as rotating a sphere preserves its radius, but that radius doesn't lie on the manifold. To the extent that one can define a notion of Lorentz contraction in de Sitter space, an object with a length equal to the radius of curvature still Lorentz contracts.
    One of the main predictions they claim to extract from de Sitter general relativity (if there is such a thing) is that the dark energy density is about the same as the matter density, which they claim as a success since it agrees with ΛCDM. But in ΛCDM the densities are only similar in the present era. At the time of decoupling, for example, the matter density was about 109 times higher while the dark energy density was the same as now. This isn't necessarily fatal—the WMAP team's analysis rules out any major variation in the dark energy density in the context of ΛCDM, but (not being familiar with the details) I can imagine that a completely new analysis based on a completely new model might agree with the data. I would expect this major disagreement with ΛCDM to be the centerpiece of their paper. That they don't even mention it suggests to me a pretty low level of understanding of the branch of science that they're trying to revolutionize.
    Either they've done a lousy job of explaining and motivating what they're really doing, or they're not really doing anything. I suspect the latter, but in either case the Wikipedia article needs to be rewritten from the ground up if it's going to stay. The article won't make sense as long as it echoes the papers. -- BenRG (talk) 07:13, 25 November 2008 (UTC)[reply]
    "One of the main predictions they claim ... is that the dark energy density is about the same as the matter density, which they claim as a success since it agrees with ΛCDM." - I can't find where they say this, could you tell me where this claim occurs? Thanks. Delaszk (talk) 12:20, 25 November 2008 (UTC)[reply]

    *Proposal Consensus seems to be heading for delete. If it comes to that, then I propose that the page be redirected to doubly special relativity since it is a form of doubly special relativity. That way all the references I've gathered could be restored if need be. Delaszk (talk) 12:56, 25 November 2008 (UTC)[reply]

    • Keep. I agree with most of the critcisms by BenRG, but we cannot delete articles on these grounds. This article should be rewritten, the promotion of the theory as an explanation for dark energy etc. in the lead should be made much less prominent, because this has yet to be scrutinized by the physics community. A reader who doesn't know this, should not get any other impression about this theory.

    Nowhere in the article could I read anything about the de Sitter algebra, which is strange as this is what everything seems to be based on. So, I think it would be much better if Delaszk rewrites this article as a mathematical physics article and explains in detail the de Sitter algebra along the lines of sections 2 and 3 of this article.

    Of course, the article would then look like a very technical exposition of a mathematical physics subject but that is what it i.m.o. should be. What you can do is mention later on in the article that this theory has been proposed to explain dark energy by the proponents. Count Iblis (talk) 17:37, 25 November 2008 (UTC)[reply]

    • Yes, but the theory that this wiki article is about seems to be founded on some Lie-algebra described in the link I gave above. I think one can have a wiki article that explains this formalism in detail and then mentions that a few physicists claim that the theory can account for dark energy. Count Iblis (talk) 14:20, 26 November 2008 (UTC)[reply]
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