Talk:Einstein–Cartan theory#This article is complete nonsense

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)

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

Please note that there are similar discussions at {{slink|Talk:Bounded mean oscillation|Recently added citation of writing of Niccolai, Edoardo}}, {{slink|Talk:Einstein–Cartan theory|Recently added citation of writing of Niccolai, Edoardo}}, and {{slink|Talk:Covariant derivative|Recently added citation of writing of Niccolai, Edoardo}}. There is also discontinued discussion at {{slink|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)

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)

The "Other" section has two sentences:

• Einstein–Cartan theory seems to allow gravitational shielding and the oscillation of massless neutrinos without violating the equivalence principle. In addition, the Einstein–Cartan theory is also related to geometrodynamics and the vortex theory of the atom.

In my opinion this content is not notable. Most of sources cited are from the late 1990s but have found very few follow up citations. The content is so spare that it has no value for readers. Should we delete this section? Johnjbarton (talk) 18:51, 13 March 2025 (UTC)

:@RemotelyInterested I removed your tags in this section as sources are given. Johnjbarton (talk) 18:53, 13 March 2025 (UTC)

On History of loop quantum gravity, the origin of Ashtekar variables in loop quantum gravity and their connection with Einstein–Cartan theory are mentioned. Wjerome2023 (talk) 09:37, 24 March 2025 (UTC)

:Wikipedia does not consider any wiki, including Wikipedia to be a reliable source. Johnjbarton (talk) 18:04, 24 March 2025 (UTC)