Talk:Topological defect

This is the discussion/talk page for: Topological defect.

Definition issues
I think the subject is too narrowly defined. After all, topological defects arise in many other context than cosmology,


 * That's why I put "In cosmology," at the top, to suggest that this wasn't the only context in which topological defects were relevant. :) Unfortunately I have no knowledge of the other contexts, perhaps you could add stubs for a few? Bryan 23:38, 8 Jun 2004 (UTC)


 * This certainly is not the definition of topological defect which is completely independent of physical system . Loosely stated, it can expressed in terms of singularities in the mapping from some manifold to a topological space. I am not very thorough in the subject either but this article seriously needs to be rewritten. - [ 203.200.95.130, 18-Jan-2006]

Often stable
The article says a topological defect is a (often) stable configuration. Does it mean it is often used to mean a stable defect or the defects are stable most of the time? Billlion 18:08, 16 Nov 2004 (UTC)


 * Textures, which are often listed as being topological defects, are in fact not stable. The other types of defects listed are stable. (Of course, it's often possible to cook up exceptions, but generally the most basic strings, domain walls and monopoles are always completely classically stable.) User:mattmartin 8 Mar 2005

Mistake?
From the article:
 * "Typically, this occurs because the boundary on which the boundary conditions are specified has a non-trivial homotopy group which is
 * preserved by differential equations; the solutions to the differential equations are then topologically distinct, and are classified
 * by their homotopy class."

I don't think the homotopy groups of the boundary are what is relevant. It is the homotopy groups of what is called the `vacuum manifold', at least for a scalar field theory. The boundary conditions constitute a map from the boundary of your space to the vacuum manifold, and it is this map which can be homotopically non-trivial. Shambolic Entity 03:32, 2 November 2006 (UTC)


 * It's not a mistake. Its one of the most basic, simplest ways to understand the topological stability of a soliton. Virtually all students are going to have a basic understanding of the homotopy groups years before they encounter the idea of a "vacuum manifold" (if they ever encounter that). 67.198.37.17 (talk) 06:12, 5 July 2017 (UTC)

Please re-review (lack of)observational evidence section
I have clarified (I hope) that the lack of direct observational evidence for domain walls, etc., only potentially "rules out" these structures within the observable universe. I attended a lecture at Stanford last night given by Andrei Linde, who made it quite clear that he believes inflation produced a volume significantly larger (to put it mildly) than the observable universe. (If I understand him correctly, enough larger that the observable universe is such a tiny fraction of this volume that we cannot even truly claim to be able to determine whether or not two parallel lines would ultimately intersect or not). At any rate, while Linde is obviously an expert on inflation, and I believe I have understood him well enough on this point, I am, nonetheless, well outside my field here, and request review of that section. Breakpoint 02:51, 7 February 2007 (UTC)

Condensed matter
Adding some material on topological defects in condensed matter. The article still needs more stuff about condensed matter applcations.

S Pat  talk 14:01, 28 November 2009 (UTC)

Jargon?
This page contains too much jargon! —Preceding unsigned comment added by 69.37.69.213 (talk)

The last section "Image"
The last section "Image" needs some explanation.
 * A soliton and an antisoliton colliding with velocities ±sinh(0.05) and annihilating.

I wonder what relation between soliton colliding and topological defect. Of course, there should be some relations between them.--Enyokoyama (talk) 01:09, 22 October 2013 (UTC)

Phone cords for younger generations haha
That phone cord example sounds like a wonderful analogy! Unfortunately a great many people now have never seen a phone cord haha! I'm just barely old enough to remember them, myself. However, most people have interacted with coils, so if we put up a picture, that should recover the analogy I think :)

Is this, perhaps, what you meant by a topological defect in a phone cord?

https://empegbbs.com/ubbthreads.php/ubb/download/Number/5832/filename/PhoneCord.jpg

(If so, I can try to get it uploaded completely properly (with permission..not that it should need that ha) and put it in the article's if that's where we want it :) I just need to make sure it's not totally the wrong phone cord phenomenon haha!)  — Preceding unsigned comment added by RProgrammer (talk • contribs) 00:57, 13 July 2020 (UTC)

In protein folding
Removed section Biochemistry, containing:

"Defects[which?] have also been found in biochemistry, notably in the process of protein folding."

While the phrase "topological defects" occurs (rarely) in the protein folding literature, I'm not sure they really mean a topological defect, but a misfolding that affects global shape. Removed until explained better with references. CyreJ (talk) 12:29, 4 December 2022 (UTC)