Talk:Thomas precession

message: This sentence: "Two boosts a small time interval (as measured in the lab frame) apart leads to a Wigner rotation after the second boost" is not correct English and needs to be rewritten.   — Preceding unsigned comment added by User135711 (talk • contribs) 16:13, 16 October 2018 (UTC)
thread_title:  unintelligible sentence 

message: Seems to be an error on the canonical form, a (1/c squared) is hanging without a differential, I think it should be dropped Bbharim (talk) 09:42, 25 December 2007 (UTC)
replies: text: It's just using units in which c=1, as is commonly done in relativity.--76.167.77.165 (talk) 02:50, 16 October 2009 (UTC)
thread_title:  error report 

message: The derivation is basically copied directly, without credit, from the book by Rindler. It's also a poor choice of derivation. Rindler is introducing the reader to general as well as special relativity, so it makes sense for him to use GR in the derivation. For this article, it would be preferable to give an explanation in terms of special relativity, such as the one in Jackson's Classical Electromagnetism.--76.167.77.165 (talk) 00:25, 3 October 2009 (UTC)
replies: text: The material has been removed as a copyvio. Charvest (talk) 01:14, 16 October 2009 (UTC)
thread_title: poor choice of derivation

message: I appreciate efforts of all contributors to improve this WP article, but it seems to me that lengthy quotation of a paper that contradicts to long well-established results violates WP policies. 
Concerning the spin precession rate, let me confirm that:
1. Two articles in External links Mathpages article on Thomas Precession  and Alternate, detailed derivation of Thomas Precession are in agreement with Jackson's Classical Electromagnetism. Jackson is in agreement with Møller.
2. The recent works by Rhodes and Semon and Krivoruchenko are in agreement with C. Møller.
3. C. Møller is in agreement with the first paper on Thomas precession published by L. Föppl and P. J. Daniell, "Zur Kinematik des Born'schen starren Körpers", Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen, 519 (1913).
4. G. B. Malykin suggests in Phys. Usp. 49, 83 (2006) that the spin precession rate is γ = 1/√(1 - v²/c²) times lower than that found by Föppl and Daniell, Møller and others. 
I actually see neither conflicting results nor serious discussions among the experts. I thus remove the lengthy quotation of Malykin's conclusions and leave one neutral reference. 
It was David Hilbert who recommended the work of Föppl and Daniell for publication. This work illustrates again the excellence of the Göttingen school.
--Gerasime (talk) 06:00, 2 May 2010 (UTC)
thread_title:  factor γ? 

message: Why have we temporarily changed the names of , , , to , , , just because the relative velocities are reversed in direction? I find this more confusing to follow, and think we should just stick to . We only need one name per frame. M∧Ŝc2ħεИτlk 22:15, 11 July 2015 (UTC)
replies: text: Agreed! YohanN7 (talk) 22:25, 11 July 2015 (UTC)
replies: text: Done. M∧Ŝc2ħεИτlk 07:41, 12 July 2015 (UTC)
thread_title:  Σ to Γ? 

message: This may seem obvious but I don't understand the velocity composition for the "inverse configuration". If the images are to be correct this needs to be cleared up.
According to the velocity addition formula, for the "forwards" composition, the velocity of  relative to  is
:\mathbf u \oplus \mathbf v = \frac{\mathbf u + \mathbf v}{1 + \frac{\mathbf u \cdot \mathbf v}{c^2}} +
\frac{1}{c^2}\frac{\gamma_u}{1+\gamma_u}\frac{\mathbf u \times(\mathbf u \times \mathbf v)} {1 + \frac{\mathbf u \cdot \mathbf v}{c^2}}.
since  moves with velocity  relative to  (first stage of composition), and  moves with velocity  relative to  (second stage).
[ It follows
:(-\mathbf{u}) \oplus (-\mathbf{v}) = -(\mathbf{u} \oplus \mathbf{v})\,\, ]
For the inverse composition, the velocity of  relative to  is surely 
:(-\mathbf{v}) \oplus (-\mathbf{u}) = - (\mathbf{v} \oplus \mathbf{u})  
since  moves with velocity  relative to  (first stage of composition), and  moves with velocity  relative to  (second stage). If this is correct, then velocity of  relative to  is then
: \mathbf{v} \oplus \mathbf{u} 
[ Aside... the axis of the Thomas rotation would surely correspond to
: (-\mathbf{v}) \times (-\mathbf{u}) = \mathbf{v} \times \mathbf{u} = - \mathbf{u} \times \mathbf{v} 
meaning a rotation in by the same angle in the opposite sense because the axis is reversed.]
So... why is the reversed composition, the velocity of  relative to , given by what is usually just stated in the papers (and this article) as it if were "obvious":
:\mathbf{v} \oplus \mathbf{u} \ldots \quad ? 
and correspondingly the velocity of  relative to  is 
: \mathbf{w}_i = - \mathbf{v} \oplus \mathbf{u} \ldots \quad ?? 
Basically... What is the ordering of velocities in the inverse configuration. Thanks, M∧Ŝc2ħεИτlk 08:22, 12 July 2015 (UTC)
replies: text: This probably boils down to notational abuse. . Horrible, and I should never have adopted it without mention (think it is from Ungar). The ordering of boosts in the inverse configuration is of course first with  and then with . YohanN7 (talk) 11:29, 12 July 2015 (UTC)

text: There is an error in the text as well. I'll fix it. YohanN7 (talk) 11:38, 12 July 2015 (UTC)
thread_title:  About the inverse configuration... 

message: How about this(?):
*Section outlining how to find rotation in principle (based on Goldstein). 
*Section carrying though calculation where second boost is infinitesimal (based on either Jackson or Goldstein)
*Section briefly listing recent attempts (based on survey in paper by Rhodes & Semon + referenced papers).
*Section on Ungar's explicit formula.
*Section on Wigner rotation as applied to QFT (based on Wigner's 1939 paper and Weinberg's QFT I)
YohanN7 (talk) 21:04, 12 July 2015 (UTC)
replies: text: Looks fine to me. M∧Ŝc2ħεИτlk 21:07, 12 July 2015 (UTC)
thread_title:  Plans 

message: Regrettably I had to remove this:
Yes, it has a reference. However...
The first paragraph is now basically superfluous, and only serves as a "intro/preview" of what's coming.
The second uses the proper time of the particle. The explanation I wrote is a rewrite of Jackson's Classical EM (2nd edition) p. 543-546 and uses the lab time for describing the accelerated motion, and transformations from the lab frame to the particle's frame at two instants of time as recorded in the lab frame. IMO this is easier to follow. So the quotation had to be cut out. Also, it is clear from the explanation that no forces or torques are required to obtain the precession. 
However, including spin back in the explanation would be better, and I don't want to dismissively remove referenced material other people have written. Spin and the reference to Ben-Menahem (1986) should be worked back in, maybe give the explanation in two segments; one for the proper time of the particle, and another for the lab time measured by the observer. M∧Ŝc2ħεИτlk 22:35, 30 December 2015 (UTC)
thread_title:  Removal of content 

message: Time dilation is a higher order effect; the Thomas precession is marginally correctly described otherwise in this article.
The precession is due to the angular offset in parallel displacements of the spin vector in the moving
frame, which is non-inertial (rotating) frame.  Purcell has a great picture of the source of the net rotation.
Time dilation does not enter at all, it is a next order effect.  — Preceding unsigned comment added by Bitsko Fignut (talk • contribs) 04:01, 12 April 2022 (UTC)
thread_title:  Time dilation is a higher order effect