Talk:Symmetry (physics)

Organisation of article

This article has the potential to be very nice. Perhaps an intuitive description of a symmetry in physics should be given before getting into the nitty-gritty of the actual symmetries. There should also be a link to spacetime symmetries somewhere in this article. Just a few ideas. MP (talk) 09:46, 27 December 2005 (UTC)

Is the following 'graph just a misplaced talk contribution??

I am unable to conceive a plausible reason why a colleague would have subordinated the following talk contrib directly below the (ten-years earlier) contrib of our colleague Mpatel, wherefore I now strike it through here, and duplicate it below at a point that would presumably have been appropriate for it if my conjecture about its intended relationship to the rest of the page is close to the mark.
--Jerzy•t 11:13, 4 October 2018 (UTC)

The concept of symmetry in physics and mathematics is so important that Wikipedia articles on symmetry should be clear and impeccably written... This and other articles on symmetry are below this standard at present... This particular article starts by saying more or less the following: Symmetry exists when a transformation leaves the object unchanged. The simple-minded but honest reader will immediately ask: If there is no change, what transformation are you talking about? If you say that a circle is symmetric under continuous rotation, how can you say that it was rotated at all? ...unless you mark a point on it before rotating it, which breaks the symmetry? Care should be taken in the leading paragraphs to prevent this kind of confusion in the reader's reasoning. — Preceding unsigned comment added by 201.75.191.252 (talk) 23:28, 17 January 2015 (UTC)

Symmetry of electric field of wire's current, Clarification requested.

Under "Invariance in Force" it currently speaks of a wire's current's electric field beaning cylindrically symmetrical, and then says: "Rotating the wire about its own axis does not change its position, hence it will preserve the field. The field strength at a rotated position is the same, but its direction is rotated accordingly." Could someone explain what is meant by this statement? I don't understand how the last sentence follows, could someone explain this or at least provide a citation for this portion if an explanation is deemed improper.--Δζ (talk) 23:46, 24 June 2010 (UTC)

Conservation Laws

I really like the inclusion of symmetries with the associated conserved quantity. However, for many of them (especially the later ones) the conserved quantity is not at all obvious/not really right. The standard model is not a quantity, and the links for time, space and charge parity are pretty useless. — Preceding unsigned comment added by Zzzzort (talk • contribs) 17:23, 6 April 2011 (UTC)

This section says that each continuous symmetry inplies a conservation law and that the converse is also true. Noether's Theorem says that a continuous symmetry implies a conservation law when the system is described by a Lagrangian or Hamiltonian and the symmetry applies to these. It is not necessarily true that a continuous symmetry implies a conservation law if there's no Lagrangian or Hamiltonian formulation, for example in a dissapative system. Also, Noether's theorem does not imply the converse and as far as I know it's not true. — Preceding unsigned comment added by NormDrez (talk • contribs) 15:48, 18 February 2014 (UTC)

Definition?

The lead does not define the article's subject; that is, Symmetry (physics). According to WP:BEGIN: "The first sentence should tell the nonspecialist reader what the subject is." The first fragment of a sentence in our article (before the m-dash) says, in brief, that symmetry is all features that exhibit the property of symmetry. When I read that, I gulped. The second fragment (after m-dash) and the second sentence both contain words in quotes that indicate, like the first fragment, that we aren't sure what we mean.

If symmetry in physics is purely theoretical then the following attempt at a definition might be something on which to start: "In physics, Symmetry is a mathematical concept that many physical laws and properties (as expressed by their equations) remain unchanged after certain other transformative events; for example, the passage of time, changes in location, rotations about an axis, reflection in a mirror, etc."

I know this is not quite right; that any definition along these lines will have to ignore 10% of the meaning. But abstract topics need to have context and context is often provided by examples. We can handle the exceptions in the second paragraph. I'm not an expert in this field but I think we can do better than a circular definition, don't you? --RoyGoldsmith (talk) 13:59, 20 September 2014 (UTC)

I made an attempt at merging two similar definitions and removing circular definition. Bhny (talk) 17:58, 20 September 2014 (UTC)

Presumably misplaced talk contrib

The concept of symmetry in physics and mathematics is so important that Wikipedia articles on symmetry should be clear and impeccably written... This and other articles on symmetry are below this standard at present... This particular article starts by saying more or less the following: Symmetry exists when a transformation leaves the object unchanged. The simple-minded but honest reader will immediately ask: If there is no change, what transformation are you talking about? If you say that a circle is symmetric under continuous rotation, how can you say that it was rotated at all? ...unless you mark a point on it before rotating it, which breaks the symmetry? Care should be taken in the leading paragraphs to prevent this kind of confusion in the reader's reasoning. — Preceding unsigned comment added by 201.75.191.252 (talk) 23:28, 17 January 2015 (UTC)

   As I noted above on this talk page, the preceding (apparently misplaced) critique (which IMO deserves more attention than I have granted to its content) probably makes no less sense at this new position; I've little doubt that at least future readers of this talk page are more likely to take note of it, than did prior ones over the last three years, of the curiously misplaced and now Struck-thru original; they may feel more urgency than I personally do, for heeding that colleague's IMO valid concern.
--Jerzy•t 11:52, 4 October 2018 (UTC)

The comment does seem to have been misplaced. Thank you for moving it. The comment is old, its originator made only a few edits immediately after that time, and much has been changed in the article since then, so the comment is stale. However, the article still needs quite a lot of work. I will take a look at it and see what I can do to improve it.—Anita5192 (talk) 16:55, 4 October 2018 (UTC)