Talk:Chirality (physics)

message: Alterations and restructuring are needed to properly represent use and meaning of the word chirality. Please join the multi-disciplinary discussion on Talk:Chirality. --Cigno 22:12, 15 November 2005 (UTC)
thread_title: Untitled

message: Two reasons.
* For massless particles, there's no difference between chirality and helicity, except for numerical factor.
* For massive particles, the two are often confused. Even this article talks about "relative chirality, which depends on the observer’s reference frame", but what it really means is that massive particles have relative helicities. As the article correctly says in the section 2, chirality is given by the operator \gamma^5. Chirality is Lorentz-invariant, and helicity is not.  --Itinerant1 05:27, 4 September 2006 (UTC)
replies: text: If you're an expert on the subject (or have knowledge) by all means please merge. Radagast83 19:58, 28 October 2006 (UTC)
thread_title:  Merge with Helicity 

message: The old definition is now (correctly) called helicity.  In the new definition, chirality tells us whether a particle transforms in a right or left handed representation of the poincare group.  Someone else can feel free to incorporate more detail.   Drkarat (talk) 18:20, 3 June 2008 (UTC)
replies: text: This article doesn't really explain what chirality is. (It does say a lot about helicity) Hopefully an expert can expand on the brief comment about left-handed and right-handed representations of the Poincare group. Mathewsyriac (talk) 20:47, 16 May 2010 (UTC)
thread_title: Chirality Fixed Up a Bit

message: I think the material discussing "absolute" vs. "relative" chirality is misleading and should be removed.  Chirality is chirality; the terms "absolute chirality" and "relative chirality" are certainly not in common usage and seem to have been invented in this article.  If there are no objections, I'll try to clean this up (and also make the definitions of chirality and helicity clearer) when I get the time.  Aiwendil42 02:15, 11 July 2007 (UTC)
replies: text: I agree entirely.  Rather than this absolute v. relative discussion, a section on chirality vs helicity would clarify things.  I've tried to clean out what I believe to be inaccuracies, though it was in a section about what things "are called" which is always debatable.PhysPhD 23:38, 4 August 2007 (UTC)

text: Though the recent changes were a step in the right direction, I think the above Chirality Explained Wrong criticism has not been adequately addressed.  We need a clear definition of chirality that differs from helicity.  Frankly, I don't know how chirality is defined geometrically, only that the Chirality operator is represented on fermions as \gamma^5 .  Also, how does the Pauli-Lubanski pseudo-vector fit into this?PhysPhD 21:27, 30 August 2007 (UTC)
thread_title: Absolute and Relative Chirality

message: Helicity is a physical space kind of thing.  If the fingers of your right hand curl in the direction of spin, and the thumb of the same hand points in the direction of the velocity (momentum direction), you have right hand helicity.  If it works in the same way for your left hand, you have left hand helicity.
In contrast, chirality is related to the charge of the weak force field the particle feels.  It is not related to the physical space, per se, but rather to an abstract space (the Dirac spinor space and the associated \gamma^5  matrix found therein.)   For example, a chiral left hand election has a weak charge of -1/2; a chiral left hand neutrino, +1/2; and any chiral right hand particle, zero.  Thus, only the left hand chirality particles feel the weak force (at least at high energy before symmetry breaking, but that is another story).  These chirality based, weak charge interactions have little to do with helicity, EXCEPT a funny thing happens as particle speed approaches that of light.  If one follows the math, one sees that helicity then approaches chirality, in effect.  For massless particles, as noted above, the speed is that of light, so helicity and chirality are the same.
The use of the terms "left hand chirality" and "right hand chirality" probably has its origin in that phenomenon (i.e., what happens as v --> c), but chirality really doesn't have a kind of physical handedness like helicity.  The choice of nomenclature, early on, has led to immense confusion over the years.
To see a simplified chart summary comparing chirality to helicity, and an in depth explanation of how the two become the same thing at the speed of light, go to Pedagogic Aids to Quantum Field Theory and scroll down to near the bottom of the page. I am unaware of any texts showing this material. —Preceding unsigned comment added by Bob108 (talk • contribs) 21:25, 22 October 2007 (UTC)
replies: text: You are assuming a fresnel zone interaction in the near field of two particles. In the absence of anything else, ie: a blob of photon infinitely removed from all other blobs of whatever, there is only angular momentum (energy) and linear momentum (energy) (excepting other forms of energy related to the dynamics of time), therefore there is no weak force in the manner that the weak force is defined. (No insult was intended, blob is in no relation to bob, as there is in the dimensional space in which I happen to inhabit). (Fractalhints (talk) 21:14, 29 January 2010 (UTC)
thread_title: Simple Summary of Chirality vs Helicity

message: Change spin to angular momentum and motion of trajectory to be linear momentum (energy considerations).
Angular momentum in the plane perpendicular to the direction of motion of linear momentum does not contain vectors in the direction of motion, all others do. That would provide you with the left and right handed orientation when your viewpoint is into the direction of motion. For all other orientations, with a viewpoint into the direction of motion, there are two vectors of angular momentum that contribute to linear momentum, one forwards, one backwards. In those particular cases you cannot use a single instantaneous point but must use both points (Alice or möbius strip orientation). There is absolutely no reason for the ideal that angular momentum must allways be in the plane perpendicular to the direction of linear momentum (not even when v-->c for linear momentum).  —Preceding unsigned comment added by Fractalhints (talk • contribs) 20:31, 29 January 2010 (UTC)
thread_title:  Helicity. 

message: If a graviton is imagined to be analagous to an Archimedes screw, then a hypothetical wraparound universe will create an effect where the circularly travelled helical gravitons (if they exist) appear to behave like anti-gravitons i.e. making objects move away from an observer, although the gravitons are still attracting the object, just in the opposite direction from which they were emitted. No-one else has made this connection as far as I'm aware a.k.a dark energy. The same principle can also be applied to the notion of electrical current in a closed loop or circuit. The concept is introduced in the FQXi essay competition 'Is Reality Digital or Analog' by Alan Lowey.  — Preceding unsigned comment added by 195.59.118.105 (talk) 12:17, 27 June 2011 (UTC)
thread_title:  Wraparound Universe Makes Helical Gravitons Behave Like Dark Energy 

message: "Only left-handed fermions interact with the weak interaction. In most circumstances, two left-handed fermions interact more strongly than right-handed or opposite-handed fermions implying that the universe has a preference for left-handed chirality," - the first sentence contradicts the second - either it's "all" or "most"... furthermore the fact that right is the opposite of left is somewhat obvious (and in this context the phrasing kinda reads like "left-handed, right-handed or opposite-handed"...)
92.230.146.4 (talk) 07:44, 29 December 2012 (UTC)
thread_title:  Questionable paragraph 

message: The articles Left-right symmetry and Chiral symmetry are technical, lacking in context and references, and cover the same topic. I propose they be merged into Chirality (physics)#Chiral_symmetry. RockMagnetist(talk) 22:41, 17 August 2015 (UTC)
replies: text: Sounds good, Left–right symmetry and chiral symmetry as sections in Chirality (physics)#Chiral_symmetry since the latter seems to be the most general. Chirality (physics) is fairly short, so could use some expansion which puts the other two articles to use. M∧Ŝc2ħεИτlk 22:57, 17 August 2015 (UTC)
replies: text: Good idea. Some effort might be warranted early on to uniformize the notation and conventions. Cuzkatzimhut (talk) 23:54, 17 August 2015 (UTC)

text: What about Mirror symmetry and P-symmetry?  Maybe I'm wrong, but aren't these essentially the same thing as Chiral symmetry?  If so, can there just be one article, with all the distinct terminologies, with redirects?  I think there is probably enough material for an article, not just a subsection.  — Preceding unsigned comment added by 70.247.174.3 (talk) 18:32, 12 September 2015 (UTC)

text: A resounding "thanks" from the community. Much better. Can take its time, now, to uniformize notation, level, and style. Cuzkatzimhut (talk) 20:12, 12 September 2015 (UTC)
thread_title:  Merger proposal 

message: Substituted at 11:33, 29 April 2016 (UTC)
thread_title: Assessment comment

message: Chirality is explained as something to do with a mirror, which involves the fact that we see a reflection with two eyes, which appear to switch our own image left/right (the mirror shows us as others see us). But why would an ordinary mirror deserve an article about physics? And what, exactly, is chirality, the subject of the article? I don't see a good definition. I see a diagram, but it doesn't make any sense: two spheres and an arrow. Are electrons chiral? Are photons chiral? Does this have to do with L and D isomers? How can an elementary particle be chiral when it is isotropic? Why are some WP articles so obscure that one gives up trying to make sense of them? David Spector (talk) 23:02, 29 July 2023 (UTC)
thread_title:  This article is puzzling