Space-time Structure Research Articles

Optical aspects of Born-Infeld BTZ black holes in massive gravity

We explore the dynamics of thin accretion disks, the radius of black hole shadows, observed intensities, and the visual characteristics of Born-Infeld BTZ black holes in massive gravity. We find out the relations for angular velocity, specific energy, and angular momentum of particles around the black hole. We observe that intense Born-Infeld electromagnetic effects lead to a reduction in the rotational motion of particles within the accretion disk, and the massive gravity slows down the orbital motion of these particles. We reveal that the influence of massive gravity parameter correlates with a reduction in the black hole’s shadow size, which suggests that massive gravity effects intensify the gravitational fields, thereby reducing the angular diameter of the shadows. On the other hand, a higher Born-Infeld parameter enlarges the black hole’s shadow, which manifests a visual relationship between the black hole’s physical dimensions and its gravitational influence. Moreover, we also uncover the optical characteristics of Born-Infeld BTZ black holes, which show that the Born-Infeld parameter greatly influences the electromagnetic field around the black hole, which affects energy distribution in the space. Finally, we observe that massive gravity significantly influences the spacetime structure near black holes, which is crucial for grasping gravitational lensing and the dynamics of accretion disks under such extreme conditions.

Semiclassical transport in two-dimensional Dirac materials with spatially variable tilt

We use Boltzmann theory to study the semi-classical dynamics of electrons in a two-dimensional (2D) tilted Dirac material in which the tilt varies in space. The spatial variation of the tilt parameter induces a non-trivial spacetime geometry on the background of which the electrons roam about. As the first manifestation of graivto-electric phenomena, we find a geometric planar Hall effect according to which a current flows in a direction transverse to the chemical potential gradient and is proportional to gxy component of the emergent spacetime structure. The longitudinal conductivity contains information about the gravitational red-shift factors. Furthermore, in the absence of externally applied electric field there can be “free-fall” or zero-bias currents that can be used as detectors of terahertz radiation.

Existence of remnants of regular black holes with de Sitter centers

We address the question of the end point of the quantum evaporation of regular black holes with the de Sitter centers specified by the algebraic structure of their stress–energy tensors [Formula: see text]. Most of the presented in the literature regular solutions belong to this class. In the case of a nonzero background cosmological constant stress–energy tensors with [Formula: see text] connect smoothly two de Sitter vacua, in the center and at infinity, and generate regular solutions to the Einstein equations, which describe the spacetime structure of regular black holes and their remnants. We show that for this class black holes their spacetime symmetry prevents a complete evaporation and provides the existence of thermodynamically stable remnants.

Holographic scattering and non-minimal RT surfaces

In the AdS/CFT correspondence, the causal structure of the bulk AdS spacetime is tied to entanglement in the dual CFT. This relationship is captured by the connected wedge theorem [1], which states that a bulk scattering process implies the existence of O(1/GN) entanglement between associated boundary subregions. In this paper, we study the connected wedge theorem in two asymptotically AdS2+1 spacetimes: the conical defect and BTZ black hole geometries. In these settings, we find that bulk scattering processes require not just large entanglement, but also additional restrictions related to candidate RT surfaces which are non-minimal. We argue these extra relationships imply a certain CFT entanglement structure involving internal degrees of freedom. Because bulk scattering relies on sub-AdS scale physics, this supports the idea that sub-AdS scale locality emerges from internal degrees of freedom. While the new restriction that we identify on non-minimal surfaces is stronger than the initial statement of the connected wedge theorem, we find that it is necessary but still not sufficient to imply bulk scattering in mixed states.

Across-horizon propagation and infinite time-dilation: An independent approach to Hawking radiation

The conformal scalar propagator as an explicit function of the Schwarzschild black-hole space-time has been established in the preceding three projects. The present project examines the precise relation which that propagator has to the amplitude the Schwarzschild black hole emit a scalar particle in a particular mode of positive energy. It is thereby established that the effect of infinite time-dilation on the event horizon results in both, the thermal radiation in the background of a static exterior space-time geometry and the detraction from thermality if energy-conservation is properly imposed as a constraint on scalar propagation. The derivation of the latter signifies an equivalent approach to the result of Parikh and Wilczek from the semi-classical perspective of the distant observer. From that perspective for that matter, Hawking radiation emerges in both contexts as the exclusive consequence of infinite time-dilation on the event horizon. These results are consistent with Hawking radiation as the exclusive consequence of the causal structure of the Schwarzschild black-hole space-time both, in a static exterior geometry and in such dynamical exterior geometry as energy-conservation signifies. The extension of the thermal case to other spin-fields and black-hole geometries is discussed.

Abstract Cyclic Functional Relation and Taxonomies of Cyclic Signals Mathematical Models: Construction, Definitions and Properties

This work is devoted to the procedure of the construction of an abstract cyclic functional relation, which summarizes and extends the known results for a cyclically correlated random process and a cyclic (cyclically distributed) random process to the case of arbitrary cyclic functional relations. Two alternative definitions of the abstract cyclic functional relation are given, and the fundamental properties of its cyclic and phase structures are presented. The theorem on the invariance of cyclicity attributes of an abstract cyclic functional relation to shifts of its argument, and which are determined by the rhythm function of this functional relation, is formulated and proved. This theorem gives the sufficient and necessary conditions that the rhythm function of an abstract cyclic functional relation must satisfy. By specifying the range of values and attributes of the cyclicity of an abstract cyclic functional relation, the definitions of important classes of cyclic functional relations are formulated. A deductive approach to building a wide system of taxonomies of classes of deterministic, stochastic, fuzzy and interval cyclic functional relations as potential mathematical models of cyclic signals is demonstrated. A comparative analysis of an abstract cyclic functional relation with the known mathematical models of cyclic signals was carried out. The results obtained in the article significantly expand and systematize the mathematical tools of the description of cyclic signals and are the basis for the development of effective model-based technologies for processing and computer simulation of signals with a cyclic space-time structure.

Kinetic theory of tilted Dirac cone materials

We formulate the Boltzmann kinetic equations for interacting electrons with tilted Dirac cones in two space dimensions characterized by a tilt parameter 0≤ζ<1. By solving the linearized Boltzmann equation, we find that the broadening of the Drude pole is enhanced by κ(ζ)×(1−ζ2)−1/2, where the κ is interaction-induced enhancement factor. The intensity of the Drude pole is also anisotropically enhanced by (1−ζ2)−1. The ubiquitous “redshift” factors (1−ζ2)1/2 can be regarded as a manifestation of an underlying spacetime structure in such solids. The additional broadening κ that arises from the interactions cannot be obtained from a simple coordinate change and are more pronounced for electrons in a ζ-deformed Minkowski spacetime of tilted Dirac fermions.

ENTROPY OF GRAVITATIONAL WAVES

Gravitational waves (GWs), the propagating perturbations within the structure of spacetime, provide a unique window into the dynamics of massive celestial objects and their cataclysmic events such as binary black hole (BBH), black hole – neutron star, binary neutron star (BNS) merger. While the detection and analysis of GWs have significantly advanced our understanding of the universe, the exploration of their information content, specifically their entropy, is not well studied and remains an intriguing avenue of research. This article presents an application of the concept of entropy to GWs and its implications for astrophysics. By using masses of the detected GW sources provided by open-source Gravitational Wave Open Science Center (GWOSC) and the PyCBC library, we generated GWs using different models and approximations. Specifically, we employed three different waveform models: IMRPhenomPv3, IMRPhenomPv2_NRTidal, and IMRPhenomXPHM. After generating GWs with different models we investigated the relationship between entropy and the masses of GW sources. Besides varying values in different models, entropy nearly exponentially decreases while the total mass of the systems providing those GWs increases. Additionally, different waveform models demonstrated varying levels of entropy. This study opens avenues for further research on the underlying physics of GWs and their detection and classification methods.

Casimir wormholes with GUP correction in the Loop Quantum Cosmology

In this paper, we obtain novel traversable, static, and spherically symmetric wormhole solutions, derived from the effective energy density and isotropic pressure resulting from the Casimir effect, corrected by the Generalized Uncertainty Principle (GUP) within the framework of Loop Quantum Cosmology (LQC). The goal is to explore the interplay between competing quantum gravity effects and quantum vacuum phenomena in the emergence of non-trivial spacetime structures. We examine features such as traversability, embedding diagrams, energy conditions, curvature, and stability of the obtained solutions. Additionally, we analyze the junction conditions required to integrate the wormhole spacetime with an external Schwarzschild spacetime and calculate the amount of exotic matter needed to maintain the wormhole. Finally, we evaluate the conditions under which this latter remains visible or is hidden by the event horizon associated with the Schwarzschild spacetime.

Beyond four dimensions: An extended study of f(R,T) theory with multidimensional metric

The present communication explores [Formula: see text]-dimensional cosmological models within the framework of the [Formula: see text] theory. The exploration is motivated by Kaluza–Klein theory, where the existence of extra dimensions becomes a focal point in understanding the fundamental forces of the universe. A cosmological model has been constructed by assuming Fractional quadratic deceleration parameter. [Formula: see text] and [Formula: see text] provide a crucial link between theoretical predictions and empirical observations. Through rigorous mathematical analysis and theoretical modeling, we investigate the implications of this extended gravitational theory on cosmic evolution and the structure of spacetime. Our findings shed light on the interplay between geometry, matter and gravitational dynamics in multidimensional space, offering new insights into the nature of gravity and cosmological phenomenon.

Causal Fermion Systems and Octonions

AbstractThe authors compare the structures and methods in the theory of causal fermion systems with approaches to fundamental physics based on division algebras, in particular the octonions. It is found that octonions and, more generally, tensor products of division algebras come up naturally to describe the symmetries of the vacuum configuration of a causal fermion system. This is achieved by associating the real and imaginary octonion basis elements with the neutrino and charged sectors of the vacuum fermionic projector, respectively. Conversely, causal fermion systems provide octonionic theories with spacetime structures and dynamical equations via the causal action principle. In this way, octonionic theories and causal fermion systems complement each other.

Exploring Fractal Quantum Field Theory in Higher-Order Dimensions Using the McGinty Equation

This hypothesis investigates the application of the McGinty Equation to quantum fields in higher-order dimensions, proposing that these fields exhibit self-similar fractal properties. The primary objective is to understand the implications of fractal geometry on quantum field interactions, coupling constants, and particle scattering processes, offering new insights into the fundamental forces and the structure of spacetime.

Space-time structures, light trajectories and shadows for Kerr-Newman-AdS black hole with surrounding perfect fluid matter in Rastall gravity

We present the horizon structures and the shadows for Kerr-Newman-AdS black hole located in perfect fluid matter field in Rastall gravity. By considering the Hamilton-Jacobi equation and Carter constant separable method, we obtain the null geodesic equations of the black hole space-time as well as the unstable circular photon orbits in terms of the impact parameters. The horizon structures of the space-time are calculated numerically. The results show that there are four roots for a general case of the horizon equation (the Cauchy horizon r−h , the event horizon r+h , the cosmological horizon r q of Rastall gravity and the cosmological horizon r c of cosmological constant), which lead to a specific characteristic with the subregions of the space-time. The influences of the cosmological horizons r q and r c on the light trajectories around the black hole are also investigated. Furthermore, we study the effects of the parameters, including the perfect fluid matter intensity N s , the Rastall parameter k λ, the cosmological constant Λ, the black hole spin a and the black hole charge Q on black hole shadows in detail.

Quantizing Galilean spacetime: a reconstruction of Maxwell’s equations in empty space

As was recently shown, non-relativistic quantum theory can be derived by means of a projection method from a continuum of classical solutions for (massive) particles. In this paper, we show that Maxwell’s equations in empty space can be derived using the same method. In this case, the starting point is a continuum of solutions of equations of motion for massless particles describing the structure of Galilean space-time. As a result of the projection, the space-time structure itself is changed by the appearance of a new fundamental constant c with the dimension of a velocity. This maximum velocity c, derived here for massless particles, is analogous to the accuracy limit ħ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbar $$\\end{document} derived earlier for massive particles. The projection method can thus be interpreted as a generalized quantization. We suspect that all fundamental fields can be traced back to continuous sets of particle trajectories, and that in this sense, the particle concept is more fundamental than the field concept.

Effect of the Weakly Divergent Acoustic Beam on the Space-Time Structure of Pulsed Signals in the Underwater Sound Channel

Effect of the Weakly Divergent Acoustic Beam on the Space-Time Structure of Pulsed Signals in the Underwater Sound Channel

Exploration of GUP-corrected Casimir wormholes in extended teleparallel gravity with matter coupling

In this manuscript, we investigate the properties of Casimir wormholes within the framework of extended teleparallel gravity, incorporating the Generalized Uncertainty Principle. Both the Casimir effect and the Generalized Uncertainty Principle (GUP) originate from the concept of a fundamental minimum length. Our analysis explores the geometric and physical traits of these wormholes, examining two distinct GUP constructions namely the Kempf, Mangano, and Mann (KMM) model and the Detournay, Gabriel, and Spindel (DGS) model and their corresponding equations of state. We find that the resulting wormhole solutions exhibit anisotropic effects and violate the null energy condition, implying the presence of exotic fluid. By employing volume integral techniques, we compute the quantity of exotic fluid, providing new insights into the nature of these wormholes. Our study sheds light on the implications of GUP-corrected Casimir wormholes for our understanding of gravity and the structure of spacetime.

Economic paradigms, public ethics, socio-economic institutions: dynamics and relationships

The article studies the relationship between ethics and economics in the context of current system’s functioning of the most important social institutions. The purpose of the study is to theoretically analyze the relation between the economic and ethical structure of society and to develop recommendations for the practical application of the results ща designing a strategy for the country's socio-economic development. The research is based on the principles of the systems approach, space-time analysis and the methodology of systemic socio-economic theory. The structure of economic paradigms is compared to the structure of ethical paradigms. The conclusion is made about their mutual conditionality and influence on the type of social structure. The dual nature of the relationship between economics and ethics is substantiated. This duality is manifested in the separation of the subject of economics and ethics in systemic terms: if the economic subjects are the processes aimed at mastering the forces of nature, then the subjects of ethics are the processes aimed at improving the system of intra-societal relations. Economics in society is comprehensive, while ethics has the property of widespread penetration into the consciousness of economic subjects. The economic and ethical spheres all together determine the structure and functions of socio-economic space-time. Strengthening the institution of reputation contributes to the dissemination and consolidation of traditional values and raising the ethical level of society. It is necessary to represent it in the strategy of the country's socio-economic development along with target guidelines for economic dynamics, as well as the desired state of the spiritual sphere of the population and generally accepted principles of ethical behavior. The possibilities of applying ethical principles in solving the problems of location and development of productive forces in the country are explored.

Building the blocks of Schwarzschild

We demonstrate that the Schwarzschild black hole can be “resolved” into bound states of Reissner-Nordström black holes in four dimensions. These bound states closely resemble the Schwarzschild geometry from the asymptotic region up to an infinitesimal distance away from the Schwarzschild horizon. Below this scale, the horizon is replaced by novel spacetime structures supported by intense and entrapped electromagnetic flux. The flux originates from collinear black holes that can be brought arbitrarily close to extremality. We find that the charge distribution follows a universal pattern, with magnitudes scaling proportionally to the total mass and alternating in sign. Moreover, the bound states always have an entropy that constitutes a fraction of the Schwarzschild entropy. Constructed in four dimensions, the black holes are kept apart by struts, for which we analyze tensions and energies. These solutions pave the way for analogous constructions in supergravity and for a brane/anti-brane description of the Schwarzschild black hole in string theory.

Hawking Temperature Modification and the Physical Dynamics of Black Holes: A Study of the Influence of Internal and Cosmological Variables

&lt;p&gt;The main objective of the study is to develop a model that modifies the traditional Hawking temperature by considering the influence of internal variables such as radius, mass, electric charge, angular momentum, and cosmological constant. The research method involves mathematical analysis and computational modeling based on the modified Hawking temperature equation. The results show that the modified Hawking temperature produces non-linear corrections that show the interaction between black holes and the quantum structure of spacetime. graphical representations visualize the variation of Hawking temperature with changes in area, electric charge, angular momentum, and cosmological parameters. The implications of the research extend to the understanding of the thermal properties of black holes in the context of gravitational and quantum theories. The research identifies gaps in the knowledge of the effects of cosmological parameters on black hole thermodynamics and introduces Hawking temperature modifications that have not been mapped in detail before. The study concludes that the Hawking temperature modification provides a strong foundation for further research in black hole physics, particularly in the effect of physical and cosmological parameters on the thermal properties of black holes.&lt;/p&gt;

Landauer Principle and the Second Law in a Relativistic Communication Scenario.

The problem of formulating thermodynamics in a relativistic scenario remains unresolved, although many proposals exist in the literature. The challenge arises due to the intrinsic dynamic structure of spacetime as established by the general theory of relativity. With the discovery of the physical nature of information, which underpins Landauer's principle, we believe that information theory should play a role in understanding this problem. In this work, we contribute to this endeavour by considering a relativistic communication task between two partners, Alice and Bob, in a general Lorentzian spacetime. We then assume that the receiver, Bob, reversibly operates a local heat engine powered by information, and seek to determine the maximum amount of work he can extract from this device. As Bob cannot extract work for free, by applying both Landauer's principle and the second law of thermodynamics, we establish a bound on the energy Bob must spend to acquire the information in the first place. This bound is a function of the spacetime metric and the properties of the communication channel.