Singularities in Spacetime

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "Gravitation".

Deadline for manuscript submissions: closed (22 March 2022) | Viewed by 10673

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Guest Editor
Mathematics Department, US Naval Academy, Annapolis, MD 21402, USA
Interests: mathematical physics; general relativity; singularities; exact solutions
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Special Issue Information

Dear Colleagues,

This Special Issue will be focused on singularities in relativistic spacetimes. Papers on the definition, existence, and nature of singularities are welcome. Boundary definitions may be explored together with the location of singularities in relativistic spacetime manifolds. Theorems on the existence of singularities in general and discussions of the various types of singularities (quasiregular, nonscalar curvature, and scalar curvature) would be of interest together with the use of invariants, both scalar polynomial and Cartan, to indicate curvature singularities. The behavior of classical and quantum particles and fields in singular spacetimes could be explored to further our understanding of the singularities present, both in exact solutions to Einstein’s equations or alternative theories and within our physical universe. Finally, approaches to quantum gravity and how they can erase classical singularities would be appropriate.

Prof. Dr. Deborah Konkowski
Guest Editor

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Keywords

  • Boundary definitions of singularities
  • Quasiregular singularities
  • Nonscalar curvature singularities
  • Scalar curvature singularities
  • Exact solutions
  • Singularity resolution

Published Papers (3 papers)

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Research

15 pages, 320 KiB  
Article
The Poincaré Index and Its Applications
by Alexander G. Aleksandrov
Universe 2022, 8(4), 223; https://0-doi-org.brum.beds.ac.uk/10.3390/universe8040223 - 02 Apr 2022
Cited by 1 | Viewed by 5415
Abstract
We discuss an approach to the problem of calculating the local topological index of vector fields given on complex spaces or varieties with singularities developed by the author over the past few years. Our method is based on the study of the homology [...] Read more.
We discuss an approach to the problem of calculating the local topological index of vector fields given on complex spaces or varieties with singularities developed by the author over the past few years. Our method is based on the study of the homology of a contravariant version of the classical Poincaré–de Rham complex. This idea allows not only simplifying the calculations, but also clarifying the meaning of the basic constructions underlying many papers on the subject. In particular, in the graded case, the index can be expressed explicitly in terms of the elementary symmetric polynomials. We also considered some useful applications in physics, mechanics, control theory, the theory of bifurcations, etc. Full article
(This article belongs to the Special Issue Singularities in Spacetime)
18 pages, 571 KiB  
Article
Self-Adjoint Extension Approach to Motion of Spin-1/2 Particle in the Presence of External Magnetic Fields in the Spinning Cosmic String Spacetime
by Márcio M. Cunha and Edilberto O. Silva
Universe 2020, 6(11), 203; https://0-doi-org.brum.beds.ac.uk/10.3390/universe6110203 - 04 Nov 2020
Cited by 4 | Viewed by 1674
Abstract
In this work, we study the relativistic quantum motion of an electron in the presence of external magnetic fields in the spinning cosmic string spacetime. The approach takes into account the terms that explicitly depend on the particle spin in the Dirac equation. [...] Read more.
In this work, we study the relativistic quantum motion of an electron in the presence of external magnetic fields in the spinning cosmic string spacetime. The approach takes into account the terms that explicitly depend on the particle spin in the Dirac equation. The inclusion of the spin element in the solution of the problem reveals that the energy spectrum is modified. We determine the energies and wave functions using the self-adjoint extension method. The technique used is based on boundary conditions allowed by the system. We investigate the profiles of the energies found. We also investigate some particular cases for the energies and compare them with the results in the literature. Full article
(This article belongs to the Special Issue Singularities in Spacetime)
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12 pages, 299 KiB  
Article
Regular Black Holes with Asymptotically Minkowski Cores
by Alex Simpson and Matt Visser
Universe 2020, 6(1), 8; https://0-doi-org.brum.beds.ac.uk/10.3390/universe6010008 - 31 Dec 2019
Cited by 96 | Viewed by 2778
Abstract
Standard models of “regular black holes” typically have asymptotically de Sitter regions at their cores. Herein, we shall consider novel “hollow” regular black holes, those with asymptotically Minkowski cores. The reason for doing so is twofold: First, these models greatly simplify the physics [...] Read more.
Standard models of “regular black holes” typically have asymptotically de Sitter regions at their cores. Herein, we shall consider novel “hollow” regular black holes, those with asymptotically Minkowski cores. The reason for doing so is twofold: First, these models greatly simplify the physics in the deep core, and second, one can trade off rather messy cubic and quartic polynomial equations for somewhat more elegant special functions such as exponentials and the increasingly important Lambert W function. While these “hollow” regular black holes share many features with the Bardeen/Hayward/Frolov regular black holes, there are also significant differences. Full article
(This article belongs to the Special Issue Singularities in Spacetime)
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