Lorentzian-Euclidean black holes and Lorentzian to Riemannian metric transitions

Fuente: arXiv
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Autores principales: Bartolo, Rossella, Caponio, Erasmo, Germinario, Anna Valeria, Sánchez, Miguel
Formato: Preprint
Publicado: 2025
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author Bartolo, Rossella
Caponio, Erasmo
Germinario, Anna Valeria
Sánchez, Miguel
author_facet Bartolo, Rossella
Caponio, Erasmo
Germinario, Anna Valeria
Sánchez, Miguel
contents In recent papers on spacetimes with a signature-changing metric, the concept of a Lorentzian-Euclidean black hole and new elements for Lorentzian-Riemannian signature change have been introduced. A Lorentzian-Euclidean black hole is a signature-changing modification of the Schwarzschild spacetime satisfying the vacuum Einstein equations in a weak sense. Here the event horizon serves as a boundary beyond which time becomes imaginary. We demonstrate that the proper time needed to reach the horizon remains finite, consistently with the classical Schwarzschild solution. About Lorentzian to Riemannian metric transitions, we stress that the hypersurface where the metric signature changes is naturally a spacelike hypersurface which can be identified with the future or past causal boundary of the Lorentzian sector. Moreover, a number of geometric interpretations appear, as the degeneracy of the metric corresponds to the collapse of the causal cones into a line, the degeneracy of the dual metric corresponds to collapsing into a hyperplane, and additional geometric structures on the transition hypersurface (Galilean and dual Galilean) might be explored.
format Preprint
id arxiv_https___arxiv_org_abs_2502_14108
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lorentzian-Euclidean black holes and Lorentzian to Riemannian metric transitions
Bartolo, Rossella
Caponio, Erasmo
Germinario, Anna Valeria
Sánchez, Miguel
General Relativity and Quantum Cosmology
Differential Geometry
In recent papers on spacetimes with a signature-changing metric, the concept of a Lorentzian-Euclidean black hole and new elements for Lorentzian-Riemannian signature change have been introduced. A Lorentzian-Euclidean black hole is a signature-changing modification of the Schwarzschild spacetime satisfying the vacuum Einstein equations in a weak sense. Here the event horizon serves as a boundary beyond which time becomes imaginary. We demonstrate that the proper time needed to reach the horizon remains finite, consistently with the classical Schwarzschild solution. About Lorentzian to Riemannian metric transitions, we stress that the hypersurface where the metric signature changes is naturally a spacelike hypersurface which can be identified with the future or past causal boundary of the Lorentzian sector. Moreover, a number of geometric interpretations appear, as the degeneracy of the metric corresponds to the collapse of the causal cones into a line, the degeneracy of the dual metric corresponds to collapsing into a hyperplane, and additional geometric structures on the transition hypersurface (Galilean and dual Galilean) might be explored.
title Lorentzian-Euclidean black holes and Lorentzian to Riemannian metric transitions
topic General Relativity and Quantum Cosmology
Differential Geometry
url https://arxiv.org/abs/2502.14108