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Symmetry
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Symmetries in the Universe
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Symmetries in the Universe

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (31 August 2020) | Viewed by 14824

Special Issue Editor

Dr. Laura Rossetto

E-Mail Website1 Website2
Guest Editor
Radboud University
Interests: astroparticle physics; cosmic-ray acceleration and propagation models; extreme processes in the universe

Special Issue Information

Dear Colleagues,

Astrophysics combines the study of the four fundamental interactions—nuclear strong and weak, electromagnetic, and gravitational—and in the past decades, extraordinary results have been obtained in discovering and understanding the processes taking place in the Universe. The Standard Model, confirmed with extraordinary precision by particle accelerator experiments, is not able to explain most of these astrophysical processes.

Many open questions are still far from being answered. Different experiments agree in reporting that baryonic matter constitutes only 5% of the entire Universe. This raises the question of what the remaining components—dark matter and dark energy—are constituted of. Another fundamental mystery is why and how matter has won over antimatter, and attempts are being made to look for different behaviour between matter and antimatter. The processes behind the acceleration of cosmic rays to the highest energies are mostly obscure, but an inverse correlation between the size of cosmic-ray sources and the intensity of their magnetic fields has been highlighted for long time. The observed isotropy of Cosmic Microwave Background radiation poses fundamental questions about the expansion of the Universe in the earliest phases.
    These different topics will be individually investigated, but the answer to each open question needs to fit the overall picture.

Dr. Laura Rossetto
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Matter–antimatter abundance ratio
  • Dark matter
  • Dark energy
  • Cosmic rays
  • Neutrino oscillations
  • Sterile neutrinos
  • CMB radiation
  • Gravitational waves
  • Turbulent evolutions
  • Astrophysical numerical simulations

Published Papers (5 papers)

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Research

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24 pages, 379 KiB  
Article
Solution of Non-Autonomous Schrödinger Equation for Quantized de Sitter Klein-Gordon Oscillator Modes Undergoing Attraction-Repulsion Transition
by Philip Broadbridge and Kathryn Deutscher
Symmetry 2020, 12(6), 943; https://doi.org/10.3390/sym12060943 - 03 Jun 2020
Cited by 3 | Viewed by 1905
Abstract
For a scalar field in an exponentially expanding universe, constituent modes of elementary excitation become unstable consecutively at shorter wavelength. After canonical quantization, a Bogoliubov transformation reduces the minimally coupled scalar field to independent 1D modes of two inequivalent types, leading eventually to [...] Read more.
For a scalar field in an exponentially expanding universe, constituent modes of elementary excitation become unstable consecutively at shorter wavelength. After canonical quantization, a Bogoliubov transformation reduces the minimally coupled scalar field to independent 1D modes of two inequivalent types, leading eventually to a cosmological partitioning of energy. Due to accelerated expansion of the coupled space-time, each underlying mode transits from an attractive oscillator with discrete energy spectrum to a repulsive unit with continuous unbounded energy spectrum. The underlying non-autonomous Schrödinger equation is solved here as the wave function evolves through the attraction-repulsion transition and ceases to oscillate. Full article
(This article belongs to the Special Issue Symmetries in the Universe)
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18 pages, 517 KiB  
Article
Scale Symmetry in the Universe
by Jose Gaite
Symmetry 2020, 12(4), 597; https://doi.org/10.3390/sym12040597 - 09 Apr 2020
Cited by 1 | Viewed by 4579
Abstract
Scale symmetry is a fundamental symmetry of physics that seems however not to be fully realized in the universe. Here, we focus on the astronomical scales ruled by gravity, where scale symmetry holds and gives rise to a truly scale invariant distribution of [...] Read more.
Scale symmetry is a fundamental symmetry of physics that seems however not to be fully realized in the universe. Here, we focus on the astronomical scales ruled by gravity, where scale symmetry holds and gives rise to a truly scale invariant distribution of matter, namely it gives rise to a fractal geometry. A suitable explanation of the features of the fractal cosmic mass distribution is provided by the nonlinear Poisson–Boltzmann–Emden equation. An alternative interpretation of this equation is connected with theories of quantum gravity. We study the fractal solutions of the equation and connect them with the statistical theory of random multiplicative cascades, which originated in the theory of fluid turbulence. The type of multifractal mass distributions so obtained agrees with results from the analysis of cosmological simulations and of observations of the galaxy distribution. Full article
(This article belongs to the Special Issue Symmetries in the Universe)
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20 pages, 1064 KiB  
Article
The Quantum Yang-Baxter Conditions: The Fundamental Relations behind the Nambu-Goldstone Theorem
by Ivan Arraut
Symmetry 2019, 11(6), 803; https://doi.org/10.3390/sym11060803 - 17 Jun 2019
Cited by 15 | Viewed by 3144
Abstract
We demonstrate that when there is spontaneous symmetry breaking in any system, relativistic or non-relativistic, the dynamic of the Nambu-Goldstone bosons is governed by the Quantum Yang-Baxter equations. These equations describe the triangular dynamical relations between pairs of Nambu-Goldstone bosons and the degenerate [...] Read more.
We demonstrate that when there is spontaneous symmetry breaking in any system, relativistic or non-relativistic, the dynamic of the Nambu-Goldstone bosons is governed by the Quantum Yang-Baxter equations. These equations describe the triangular dynamical relations between pairs of Nambu-Goldstone bosons and the degenerate vacuum. We then formulate a theorem and a corollary showing that these relations guarantee the appropriate dispersion relation and the appropriate counting for the Nambu-Goldstone bosons. Full article
(This article belongs to the Special Issue Symmetries in the Universe)
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12 pages, 249 KiB  
Article
Do Fractals Confirm the General Theory of Relativity?
by Irina Rozgacheva
Symmetry 2019, 11(6), 740; https://doi.org/10.3390/sym11060740 - 01 Jun 2019
Viewed by 2245
Abstract
The relatively high abundance of fractal properties of complex systems on Earth and in space is considered an argument in support of the general relativity of the geometric theory of gravity. The fractality may be called the fractal symmetry of physical interactions providing [...] Read more.
The relatively high abundance of fractal properties of complex systems on Earth and in space is considered an argument in support of the general relativity of the geometric theory of gravity. The fractality may be called the fractal symmetry of physical interactions providing self-similarities of complex systems. Fractal symmetry is discrete. A class of geometric solutions of the general relativity equations for a complex scalar field is offered. This class allows analogy to spatial fractals in large-scale structures of the universe due to its invariance with respect to the discrete scale transformation of the interval d s ↔ q d s ˜ . The method of constructing such solutions is described. As an application, the treatment of spatial variations of the Hubble constant H 0 H S T (Riess et al., 2016) is considered. It is noted that the values H 0 H S T form an almost fractal set. It has been shown that: a) the variation H 0 H S T may be connected with the local gravitational perturbations of the space-time metrics in the vicinity of the galaxies containing Cepheids and supernovae selected for measurements; b) the value of the variation H 0 H S T can be a consequence of variations in the space-time metric on the outskirts of the local supercluster, and their self-similarity indicates the fractal distribution of matter in this region. Full article
(This article belongs to the Special Issue Symmetries in the Universe)

Review

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13 pages, 376 KiB  
Review
Dark Matter Candidates with Dark Energy Interiors Determined by Energy Conditions
by Irina Dymnikova
Symmetry 2020, 12(4), 662; https://doi.org/10.3390/sym12040662 - 22 Apr 2020
Cited by 6 | Viewed by 2152
Abstract
We outline the basic properties of regular black holes, their remnants and self-gravitating solitons G-lumps with the de Sitter and phantom interiors, which can be considered as heavy dark matter (DM) candidates generically related to a dark energy (DE). They are specified by [...] Read more.
We outline the basic properties of regular black holes, their remnants and self-gravitating solitons G-lumps with the de Sitter and phantom interiors, which can be considered as heavy dark matter (DM) candidates generically related to a dark energy (DE). They are specified by the condition T t t = T r r and described by regular solutions of the Kerr-Shild class. Solutions for spinning objects can be obtained from spherical solutions by the Newman-Janis algorithm. Basic feature of all spinning objects is the existence of the equatorial de Sitter vacuum disk in their deep interiors. Energy conditions distinguish two types of their interiors, preserving or violating the weak energy condition dependently on violation or satisfaction of the energy dominance condition for original spherical solutions. For the 2-nd type the weak energy condition is violated and the interior contains the phantom energy confined by an additional de Sitter vacuum surface. For spinning solitons G-lumps a phantom energy is not screened by horizons and influences their observational signatures, providing a source of information about the scale and properties of a phantom energy. Regular BH remnants and G-lumps can form graviatoms binding electrically charged particles. Their observational signature is the electromagnetic radiation with the frequencies depending on the energy scale of the interior de Sitter vacuum within the range available for observations. A nontrivial observational signature of all DM candidates with de Sitter interiors predicted by analysis of dynamical equations is the induced proton decay in an underground detector like IceCUBE, due to non-conservation of baryon and lepton numbers in their GUT scale false vacuum interiors. Full article
(This article belongs to the Special Issue Symmetries in the Universe)
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