English

Cotton gravity is not predictive

General Relativity and Quantum Cosmology 2024-08-14 v3 Cosmology and Nongalactic Astrophysics High Energy Physics - Theory

Abstract

It is well-known that the theory of Cotton gravity proposed by Harada is trivially solved by all isotropic and homogeneous cosmologies. We show that this under-determination is more general. More precisely, the degree of arbitrariness in the solutions increases with the degree of symmetry. We give two simple examples. The first is that of static spherically symmetric solutions, which depend on an arbitrary function of the radial coordinate. The second is that of anisotropic cosmologies, which depend on an arbitrary function of time.

Keywords

Cite

@article{arxiv.2312.17662,
  title  = {Cotton gravity is not predictive},
  author = {Gérard Clément and Khireddine Nouicer},
  journal= {arXiv preprint arXiv:2312.17662},
  year   = {2024}
}

Comments

11 pages, revised augmented version, incorporates input from arXiv:2401.16008

R2 v1 2026-06-28T14:04:39.764Z