Talk:Homology sphere

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 Field: Topology


"Link" cross-reference[edit]

Near the end of the current article, the "link" of a vertex in a triangulated manifold is mentioned, but it is cross-referenced to a different meaning of link (disjoint embeddings of S^1 --> S^3). Is there an article for Thurston's (and others) meaning of the word link? Are the two related (other than that the links of the cusps of a link-complement are the link)? —Preceding unsigned comment added by Lewallen (talkcontribs) 22:02, 10 March 2008 (UTC)

I fixed the (hyper)link to point to Link (geometry) which is closer to the intended meaning. Even this is not quite adequate, though, as the article Link (geometry) seems to describe the link only in a 2-dimensional simplicial complex. So the article Link (geometry) needs to be fixed. VectorPosse (talk) 22:56, 10 March 2008 (UTC)

Redirection of "Poincare Sphere"[edit]

"Poincare sphere" redirects here, however there is another use of the term. In optics, the polarisation state of (fully polarised) light is often described as lying at some position on the "Poincare sphere". In this usage, the Poincare sphere is analogous to a Bloch sphere (especially so for individual photons). Besides the first two results which are Wikipedia, Google seems of the opinion that this is the common usage of the term "Poincare sphere". Perhaps someone (more knowledgeable than I on editing WP) should do something about this. QTachyon 03:03, 25 October 2007 (UTC)

n > 3[edit]

There is more to say in dimension n > 3; but this article doesn't say it. Charles Matthews (talk) 15:48, 17 November 2009 (UTC)

Cosmology[edit]

The hypothesis that the universe can be described as a Poincare Sphere was, at the time it was suggested in 2003, quite controversial with a number of astronomers saying it had already been disproved. See for example the comments on Prof. Ned Wright's news page at the time:

"A twelve-sided Universe? - Probably not."

In particular the following article cited at the above link quotes Spergel, Cornish and Tegmark:

New York Times

That article suggests the question could be resolved within a few months, and that was six years ago. Should not the Wiki article at least indicate that the claim was contentious and if possible cite some sources addressing the follow-up investigations? There are many discredited speculations in cosmology and some indication should be given if this isn't, as it appears from the page, a mainstream view.

George Dishman 13:59, 18 December 2009 (UTC) —Preceding unsigned comment added by GeorgeDishman (talkcontribs)