Talk:Einstein–Cartan theory

EC Kills the Big Bang Theory

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)

No it doesn't. --mfb (talk) 23:23, 29 December 2018 (UTC)

Explain yourself why not. 47.201.182.47 (talk) 03:24, 31 December 2018 (UTC)

You made a claim, you have to back it up. --mfb (talk) 05:01, 31 December 2018 (UTC)

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)

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)

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)

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)

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)

No it doesn't, and your constant misrepresentations of this theory get annoying. --mfb (talk) 11:10, 1 January 2019 (UTC)

You still have yet to explain yourself. 47.201.182.47 (talk) 15:27, 1 January 2019 (UTC)

EC is standard, but the claims about it requiring non-singular fermions sound like crackpottery. A look at the red shows that the non-singularity is a conjecture. cheers, Michael C. Price ^talk 01:04, 14 January 2019 (UTC)

the red ? what red ? 47.201.182.47 (talk) 01:20, 16 January 2019 (UTC)

reference cheers, Michael C. Price ^talk 04:10, 16 January 2019 (UTC)

The main field equations contain the wrong variation

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)

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)

Recently added citation of writing of Niccolai, Edoardo

I recommend removal of the citation to a writing of Niccolai, Edoardo (recently added by JeppOne (talk · contribs)), unless it can be supported as reliable and noteworthy.

Please note that there are similar discussions at Talk:Bounded mean oscillation § Recently added citation of writing of Niccolai, Edoardo, Talk:Einstein–Cartan theory § Recently added citation of writing of Niccolai, Edoardo, and Talk:Covariant derivative § Recently added citation of writing of Niccolai, Edoardo. There is also discontinued discussion at User talk:JeppOne § Articles by Niccolai, Edoardo. —Quantling (talk | contribs) 13:41, 1 May 2023 (UTC)

I'm just trying to let people know that there are some important writings by my professor. That's all. And I do it for the love of science. Maybe you should inquire about the person in question before "triggering" an unfair censorial judgment, which is to the detriment of the knowledge itself.

Thank you very much JeppOne (talk) 11:57, 2 May 2023 (UTC)

There are thousands of articles published annually on this and related topics. Singling out one gives it too much prominence. It needs to be notable in some way. Wikipedia is not a dumping ground for citations.67.198.37.16 (talk) 05:10, 6 June 2023 (UTC)

That said, a quick skim indicates that the following is a high-quality work, and could very well be appropriate for this article:

• https://hal.science/hal-03948127 Spin & Torsion Tensors on Gauge Gravity: a Re-examination of the Einstein–Cartan Spatio-Temporal Theory

I will try to read it in the coming weeks; I have high hopes for it. 67.198.37.16 (talk) 04:03, 7 June 2023 (UTC)

Many primary references to work by Nikodem J. Popławski

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)