Obstructions to distinguished Riemannian metrics via Lorentzian geometry

Fuente: arXiv
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Autore principale: Aazami, Amir Babak
Natura: Preprint
Pubblicazione: 2022
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author Aazami, Amir Babak
author_facet Aazami, Amir Babak
contents We approach the problem of finding obstructions to curvature distinguished Riemannian metrics by considering Lorentzian metrics to which they are dual in a suitable sense. Obstructions to the latter then yield obstructions to the former. This framework applies both locally and globally, including to compact manifolds, and is sensitive to various aspects of curvature. Here we apply it in two different ways. First, by embedding a Riemannian manifold into a Lorentzian one and utilizing Penrose's "plane wave limit," we find necessary local conditions, in terms of the Hessian of just one function, for large classes of Riemannian metrics to contain within them those that have parallel Ricci tensor, or are Ricci-flat, or are locally symmetric. Second, by considering Riemannian metrics dual to constant curvature Lorentzian metrics via a type of Wick rotation, we are able to rule out the existence of a family of compact Riemannian manifolds (in all dimensions) that deviate from constant curvature in a precise sense.
format Preprint
id arxiv_https___arxiv_org_abs_2207_14701
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Obstructions to distinguished Riemannian metrics via Lorentzian geometry
Aazami, Amir Babak
Differential Geometry
General Relativity and Quantum Cosmology
We approach the problem of finding obstructions to curvature distinguished Riemannian metrics by considering Lorentzian metrics to which they are dual in a suitable sense. Obstructions to the latter then yield obstructions to the former. This framework applies both locally and globally, including to compact manifolds, and is sensitive to various aspects of curvature. Here we apply it in two different ways. First, by embedding a Riemannian manifold into a Lorentzian one and utilizing Penrose's "plane wave limit," we find necessary local conditions, in terms of the Hessian of just one function, for large classes of Riemannian metrics to contain within them those that have parallel Ricci tensor, or are Ricci-flat, or are locally symmetric. Second, by considering Riemannian metrics dual to constant curvature Lorentzian metrics via a type of Wick rotation, we are able to rule out the existence of a family of compact Riemannian manifolds (in all dimensions) that deviate from constant curvature in a precise sense.
title Obstructions to distinguished Riemannian metrics via Lorentzian geometry
topic Differential Geometry
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2207.14701