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Universe, Volume 7, Issue 1

2021 January - 20 articles

Cover Story: This is basic review of zeta functions and the zeta-regularization method, starting from the notions of harmonic series and of divergent sums. By way of simple examples, it is shown how these powerful methods are used for the regularization of physical quantities, such as quantum vacuum fluctuations in various contexts. Specifically, in Casimir effect setups—with a note on the dynamical Casimir effect—and mainly concerning its application in quantum theories in curved spaces, used in gravity theories and cosmology. A brief introduction to large scale cosmology leads then to the FLRW model, and to the cosmological constant problem. A concise summary of all these interrelated subjects and applications involving zeta functions and the cosmos, and an updated list of the pioneering and more influential works (in terms of citation counts) published on all those matters up to now, are provided. View this paper.
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Articles (20)

  • Article
  • Open Access
4 Citations
2,981 Views
15 Pages

19 January 2021

In this work, supervised artificial neural networks (ANN) with rapidity–mass matrix (RMM) inputs are studied using several Monte Carlo event samples for various pp collision processes. The study shows the usability of this approach for general...

  • Article
  • Open Access
23 Citations
5,111 Views
17 Pages

Correlations between Earthquake Properties and Characteristics of Possible ULF Geomagnetic Precursor over Multiple Earthquakes

  • Khairul Adib Yusof,
  • Mardina Abdullah,
  • Nurul Shazana Abdul Hamid,
  • Suaidi Ahadi and
  • Akimasa Yoshikawa

19 January 2021

In this study, we improved and adapted existing signal processing methods on vast geomagnetic field data to investigate the correlations between various earthquake properties and characteristics of possible geomagnetic precursors. The data from 10 ma...

  • Article
  • Open Access
58 Citations
5,536 Views
68 Pages

The Clustering Dynamics of Primordial Black Holes in N-Body Simulations

  • Manuel Trashorras,
  • Juan García-Bellido and
  • Savvas Nesseris

15 January 2021

We explore the possibility that Dark Matter (DM) may be explained by a nonuniform background of approximately stellar mass clusters of Primordial Black Holes (PBHs) by simulating the evolution from recombination to the present with over 5000 realisat...

  • Article
  • Open Access
1 Citations
3,106 Views
11 Pages

Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz

  • Xiang Liu,
  • Xin Wang,
  • Ning Chang,
  • Jun Liu,
  • Lang Cui,
  • Xiaofeng Yang and
  • Thomas P. Krichbaum

14 January 2021

Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) whic...

  • Feature Paper
  • Review
  • Open Access
16 Citations
9,623 Views
11 Pages

12 January 2021

I give a historical survey of the discussions about the existence of closed timelike curves in general relativistic models of the universe, opening the physical possibility of time travel in the past, as first recognized by K. Gödel in his rotat...

  • Feature Paper
  • Article
  • Open Access
25 Citations
3,790 Views
35 Pages

12 January 2021

It is well known that Einstein’s equations assume a simple polynomial form in the Hamiltonian framework based on a Yang-Mills phase space. We re-examine the gravitational dynamics in this framework and show that time evolution of the gravitatio...

  • Communication
  • Open Access
6 Citations
2,744 Views
10 Pages

9 January 2021

The scalar field of space-time film is considered as unified fundamental field. The field model under consideration is the space-time generalization of the model for a two-dimensional thin film. The force and metrical interactions between solitons ar...

  • Article
  • Open Access
14 Citations
3,618 Views
14 Pages

Gravitational Waves in Scalar–Tensor–Vector Gravity Theory

  • Yunqi Liu,
  • Wei-Liang Qian,
  • Yungui Gong and
  • Bin Wang

In this paper, we study the properties of gravitational waves in the scalar–tensor–vector gravity theory. The polarizations of the gravitational waves are investigated by analyzing the relative motion of the test particles. It is found th...

  • Article
  • Open Access
3 Citations
4,296 Views
20 Pages

7 January 2021

The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Bel...

  • Article
  • Open Access
12 Citations
3,514 Views
18 Pages

Statistical Estimates of the Pulsar Glitch Activity

  • Alessandro Montoli,
  • Marco Antonelli,
  • Brynmor Haskell and
  • Pierre Pizzochero

A common way to calculate the glitch activity of a pulsar is an ordinary linear regression of the observed cumulative glitch history. This method however is likely to underestimate the errors on the activity, as it implicitly assumes a (long-term) li...

  • Article
  • Open Access
10 Citations
3,965 Views
44 Pages

Neutrino Oscillations in Neutrino-Dominated Accretion Around Rotating Black Holes

  • Juan David Uribe,
  • Eduar Antonio Becerra-Vergara and
  • Jorge Armando Rueda

In the binary-driven hypernova model of long gamma-ray bursts, a carbon–oxygen star explodes as a supernova in the presence of a neutron star binary companion in close orbit. Hypercritical (i.e., highly super-Eddington) accretion of the ejecta...

  • Article
  • Open Access
7 Citations
2,542 Views
11 Pages

31 December 2020

We have studied the possible isospin corrections on the skewness and kurtosis of net-baryon and net-charge fluctuations in the isospin asymmetric matter formed in relativistic heavy-ion collisions at RHIC-BES energies, based on a 3-flavor Polyakov-lo...

  • Article
  • Open Access
5 Citations
5,673 Views
33 Pages

28 December 2020

Ever since Eddington’s analysis of the gravitational redshift a century ago, and the arguments in the relativity community that it produced, fine details of the roles of proper time and coordinate time in the redshift remain somewhat obscure. W...

  • Communication
  • Open Access
4 Citations
3,459 Views
8 Pages

Comparison of Gravitational and Light Frequency Shifts in Rubidium Atomic Clock

  • Alexey Baranov,
  • Sergey Ermak,
  • Roman Lozov and
  • Vladimir Semenov

24 December 2020

The article presents the results of an experimental study of the external magnetic field orientation and magnitude influence on the rubidium atomic clock, simulating the influence of the geomagnetic field on the onboard rubidium atomic clock of navig...

  • Article
  • Open Access
1 Citations
2,710 Views
12 Pages

22 December 2020

Short timescale variability is often associated with a black hole system. The consequence of an electromagnetic outflow suddenly generated near a Kerr black hole is considered assuming that it is described by a solution of a force-free field with a n...

  • Article
  • Open Access
61 Citations
3,658 Views
17 Pages

22 December 2020

Classical black holes contain a singularity at their core. This has prompted various researchers to propose a multitude of modified spacetimes that mimic the physically observable characteristics of classical black holes as best as possible, but that...

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Universe - ISSN 2218-1997