Talk:Einstein–Cartan theory

message: EC kills  the  big  bang  theory,  and  black  hole  nonsense, ie,  no  singularities.  That  is  why  many  are  horrified  to  learn  of  EC,  which  is  a  perfectly  viable  alternative  to GR.  Cartan  was  right. Excellent article. 47.201.182.47 (talk) 14:03, 29 December 2018 (UTC)
replies: text: No it doesn't. --mfb (talk) 23:23, 29 December 2018 (UTC)
replies: text: Explain yourself why not. 47.201.182.47 (talk) 03:24, 31 December 2018 (UTC)
replies: text: You made a claim, you have to back it up. --mfb (talk) 05:01, 31 December 2018 (UTC)
replies: text: It  says  so  right  in  the  Wikipedia  article,  no  singularities.  Big  bang  and  black  holes  are  based  on  singularities. So  no  big  bang  and  no  black  holes. That  should  be  simple  enough  for  you to understand. 47.201.182.47 (talk) 05:36, 31 December 2018 (UTC)
replies: text: You didn't support your original claim at all. Anyway: The purpose of talk pages is to improve the article, and I don't see how you would contribute to that. If you have a specific suggestion for changes to the article then please write that. --mfb 05:52, 31 December 2018 (UTC)
replies: text: The  article  already  says  what  I  am  saying. I'd  like  it  to  be  even  more  strongly  put. No singularities  refutes  the  standard  accounts  of  the  big  bang theory, the universe  beginning  out of  a  point  singularity, and  black  holes, matter collapsing  into  a point singularity. 47.201.182.47 (talk) 14:35, 31 December 2018 (UTC)
replies: text: It doesn't refute anything. It is an alternative theory, and so far we don't have experiments to rule out either. --mfb (talk) 22:04, 31 December 2018 (UTC)
replies: text: Cartan shows we can have gravity without any big bang, or any black holes. I'll  take  it. 47.201.182.47 (talk) 23:56, 31 December 2018 (UTC)
replies: text: No it doesn't, and your constant misrepresentations of this theory get annoying. --mfb (talk) 11:10, 1 January 2019 (UTC)
replies: text: You still have yet to explain yourself. 47.201.182.47 (talk) 15:27, 1 January 2019 (UTC)

text: the  red ?  what  red ? 47.201.182.47 (talk) 01:20, 16 January 2019 (UTC)
thread_title: EC  Kills  the  Big Bang  Theory

message: The field equations obtained by varying the Lagrangian with respect to the metric are incorrect, and incorrectly described.
The tensor R_{ab} that results from varying the gravitational Lagrangian with respect to the metric g_{ab} must be symmetric because the metric is symmetric. Also, R_{ab} is not the Ricci tensor, which is the singly-contracted Riemann tensor, and which is generally nonsymmetric in EC.
A better procedure (the correct procedure) is to vary the Lagrangian with respect to the frame field (not the metric), which consists of the translational connection coefficients in affine geometry. I shall denote the frame field by Fr_{ab}. Varying the Lagrangian with respect to the frame field has two important effects.
a) The result R_{ab} is the full non-symmetric Ricci tensor. 
b) The variation of the matter Lagrangian yields the correct non-symmetric momentum tensor. The momentum tensor of EC must be non-symmetric because its non-symmetric part enables Einstein-Cartan theory to model exchange of intrinsic and orbital angular momentum, which general relativity cannot do (because GR is based on Riemannian geometry where the Ricci tensor must be symmetric, so the momentum tensor must be symmetric). 
This computation makes clear that Einstein-Cartan theory is an affine theory, not a metric theory.
I have not commented on this article in about five years. However, the main field equation is wrong, and the description does not correclty describe the incorrect field equation that is in the article. I have responded because of the importance of EC in the future of gravitational physics, despite the strong resistance to it. 
As Planck said, “A new scientific truth [that alters the elements of a field] does not triumph by persuading its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” --Max Planck, “Scientific Autobiography and Other Papers,” 1949, p 33-34. Quoted in “The Structure of Scientific Revolutions,” 4th edition, 2012, by Thomas Kuhn, p 150.
Rjpetti (talk) 15:29, 27 August 2019 (UTC)
replies: text: You are almost surely correct about the importance of this theory. Do you understand it well enough to make the needed corrections? 67.198.37.16 (talk) 05:29, 6 June 2023 (UTC)
thread_title: The main field equations contain the wrong variation

message: The article currently has 7/23 references to work by Nikodem J. Popławski. Absent secondary references this is WP:UNDUE.
If there are reviews that cite this work they should be summarized and cited (in addition to key primary refs).  If there are not reviews then the work is not notable and should be removed. Johnjbarton (talk) 16:04, 13 March 2024 (UTC)
thread_title:  Many primary references to work by Nikodem J. Popławski