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In this paper, we explore the possibility of formation of a traversable wormhole in General Relativity supported by particle creation mechanism. The repulsive back-reaction pressure generated through this mechanism can be thought of as a source of sustaining a traversable wormhole. In the first part of this paper, we model a wormhole geometry by assuming an inverse powerlaw variation of particle creation pressure within the wormhole geometry, and the shape function for the wormhole is obtained, assuming a finite redshift function. By stabilizing the wormhole structure, based on the causality of sound-speed we obtained the existence range of the parameter β associated with particle creation mechanism. The general shape function obtained is found to adhere to the feasibility conditions of a viable wormhole geometry. Then we studied the 2D and 3D embedding derived for the obtained shape function. In the second part of the paper, we followed the reverse approach of the aforementioned treatment, where we derived the particle creation pressures by assuming three commonly utilized toy shape-functions. The energy conditions are then investigated for all these cases. In essence, particle creation phenomena inside the wormhole may indeed provide for the possibility of sustenance of stable wormhole structure. [ABSTRACT FROM AUTHOR]

We explore relativistic quantum dynamics of spin- bosonic fields governed by the Duffin–Kemmer–Petiau (DKP) equation within the context of a topologically charged Ellis–Bronnikov-type wormhole. We derive the radial equation for the quantum systems described by the DKP equation on this wormhole background, ultimately arriving at the confluent Heun differential equation form. As a specific case, we present the ground energy level and the corresponding wave function of this quantum system. Furthermore, we extend our investigation to the DKP oscillator in the considered wormhole background, employing a similar methodology to deduce the ground state energy levels and wave function of the quantum oscillator field. Additionally, we introduce a zeroth component of the electromagnetic four-vector potential and examine the DKP oscillator by considering two types of potential on this wormhole background. Our findings highlight the influence of the wormhole throat radius and the topological charge of the geometry. Moreover, we observe that different external potentials also impact the energy levels of this relativistic quantum system. [ABSTRACT FROM AUTHOR]

This paper focuses on the examination of stable and unstable geometrical structures of thin-shell wormholes constructed from Henneaux–Martinez–Troncoso–Zanelli black holes through the Visser cut-and-paste approach. We use the Israel thin-shell formalism for evaluating the stress–energy tensor components of the matter distribution near the wormhole throat. Equations of state, specifically the phantom-like and generalized Chaplygin gas model for exotic matter, are used to conduct an extensive investigation into the stability of the thin-shell. The radial perturbation around the equilibrium throat radius is also considered to explore the stable configuration for specific values of physical parameters. Our results show that the stable zones of these thin-shell wormholes increase as the scalar field parameter ℰ approaches −1. This study gives light on the behavior and dynamics of these wormholes throw light on their potential stability and lead the way for additional theoretical physics research. [ABSTRACT FROM AUTHOR]

This work aims to explore the possibility of wormholes (WHs) fenced by fuzzy Dark Matter (FDM) haloes relying on the Einasto density profile (EDP). The research explains how combining the EDP with an anisotropic stress-energy momentum tensor leads to the formation of WH solutions corresponding to different Einasto index values. We have investigated the existence of fuzzy WHs and developed the shape function for them. An analysis is conducted on the active gravitational mass and the lodging diagrams for a certain form of the shape function. Additionally, we have also examined the exotic matter’s breach of the null energy conditions, the equilibrium conditions, and the complexity factor associated with the fuzzy WHs. [ABSTRACT FROM AUTHOR]

Using Darmois-Israel-Sen junction conditions, and with help of Visser's cut-and-paste method, we study the dynamics of thin-shell wormholes that are made of two conformally Killing gravity (a.k.a Harada gravity) black holes. We check the energy conditions for different values of the new parameter that Harada introduced, as alternative for dark energy. We examine the radial acceleration to reveal the attractive and repulsive characteristics of the thin-shell wormhole throat. We consider the dynamics and stability of the wormhole around the static solutions of the linearized radial perturbations at the wormhole throat. Finally, we determine the regions of stability by applying the concavity test on the "speed of sound" as a function in the throat radius and other spacetime parameters, particularly the new Harada parameter. [ABSTRACT FROM AUTHOR]

In this work, we have obtained new phantom fluid-type traversable wormhole (WH) solutions in the context of f (R , T) modified gravity. We investigate the potential that some equations of state (EoS), specifically phantom energy, which describes the accelerated expansion of the universe, could support the existence of traversable wormholes. This cosmic fluid thus offers us a plausible explanation for the occurrence of WH geometries. We construct two WH models with matter Lagrangian density L m = - (- ρ + P r + 2 P t) and inspect numerous characteristics of these models under the WH geometry. The first WH solution (WH-I) is discovered by utilising a linear barotropic equation of state (EoS) connected with phantom energy ω < - 1 indicating the presence of the phantom fluid and pointing to the Universe's expansion, while in the second WH (WH-II) solution, we take into account an interesting EoS ρ = η (P t - P r) to generate a WH model. Additionally, it showed that the phantom fluid WH-I solution violates the radial null energy condition (NEC) while tangential NEC is satisfied. On the other hand, for the WH-II solution, NEC is violated. Extensive detailed discussions of the matter components have been done via graphical analysis. The obtained WH geometries satisfy a stable WH's physically acceptable criteria. [ABSTRACT FROM AUTHOR]

This paper investigates a possible wormhole and associated metrics, and the physical consequences of these geometries. Using the wormhole metric, the solution of Einstein's equation suggests that the energy density component of the energy-momentum tensor is negative. This result implies that a stable wormhole requires negative energy, and is consistent with Penrose's theory. An evaluation of a representative set of spacetime geometries suggests that the occurrence of negative energy does not universally occur in every theoretical spacetime geometry. It does not occur in flat spacetime or in the Schwarzschild geometry. Negative energies theoretically occur under a limited set of conditions for a general static spherical geometry and the Friedmann-Robertson-Walker spacetime. [ABSTRACT FROM AUTHOR]

This study explores the generalized embedded wormhole (WH) solutions in the background of f (ℛ ,) gravity, where ℛ represents the Ricci scalar and denotes the Gauss–Bonnet invariant. To investigate the necessary structures of the WH solutions we thoroughly analyzed the energy conditions under f (ℛ ,) gravity within the anisotropic source of matter. To meet this aim, we consider spherically symmetric geometry with the most generic gravity model of the gravity. A modified version of the field equations is calculated for two different embedded WH solutions. All the energy conditions are calculated and shown graphically with the regional ranges of the model parameter. Further, the invalid region of the energy conditions confirms the presence of exotic matter. Finally, we have concluding remarks. [ABSTRACT FROM AUTHOR]

The concept of wormholes is still hypothetical in physics but attractive among researchers. In this work, motivated by the important effect of f (R , T) gravity theory, we seek the existence of wormhole solutions. We consider the field equations that can be derived from two different choices of matter Lagrangian density and utilize them to find the possibility of having some wormhole geometry. This procedure is based on the specific choice of an equation-of-state that obeys a certain physical requirement on the matter stress-energy [S. Kar and D. Sahdev, Restricted class of traversable wormholes with traceless matter, Phys. Rev. D 52 (1995) 2030]. For this purpose, the functional form of the redshift function is taken into consideration, and the possible existence of wormhole solutions is proven. Finally, the work examines the energy conditions and shows that violations of null energy conditions hold throughout spacetime. [ABSTRACT FROM AUTHOR]

Most numerical simulations for modeling acid reactive fluid transport and wormhole propagation during matrix acidizing, waterflooding, and CO2 sequestration in carbonate formations are computationally expensive, limiting real-time reservoir management and deep learning training datasets generation for inverse modeling research. Therefore, there is a need for less computationally expensive acid-reactive fluid flow models with adequate accuracy. This study developed and validated a simplified acid reactive-transport model by integrating a simplified Stokes–Brinkman model (as opposed to Darcy's law), an averaged continuum model, and a pseudo-fracture model. Using FEniCS, the model effectively simulates acid-reactive fluid transport and wormhole propagation in carbonate rocks, achieving a high R-square value of about 0.97 based on a quantitative comparison of the breakthrough volume with other models. The simplified model can also simulate wormhole propagation for the reciprocal of the Damköhler number (1/Da) ranging from 0.001 to 1 with adequate accuracy. Sensitivity studies on the natural fracture parameters such as orientation, length, width, and density showed that higher fracture density, wider fracture aperture, longer fracture length, and orientation aligned with the direction of acid injection contribute to lower pore volume to breakthrough ratio but may not increase long-term acid stimulation efficiency. Also, the presence or absence of fractures in the matrix does not alter the dissolving patterns and optimum injection rate. This simple acid reactive-transport model can generate large training datasets for developing surrogate models in deep learning research. Finally, the FEniCS code in this paper is shared so future researchers can reproduce the results or extend the research work. [ABSTRACT FROM AUTHOR]

Abstract Most numerical simulations for modeling acid reactive fluid transport and wormhole propagation during matrix acidizing, waterflooding, and CO2 sequestration in carbonate formations are computationally expensive, limiting real-time reservoir management and deep learning training datasets generation for inverse modeling research. Therefore, there is a need for less computationally expensive acid-reactive fluid flow models with adequate accuracy. This study developed and validated a simplified acid reactive-transport model by integrating a simplified Stokes–Brinkman model (as opposed to Darcy’s law), an averaged continuum model, and a pseudo-fracture model. Using FEniCS, the model effectively simulates acid-reactive fluid transport and wormhole propagation in carbonate rocks, achieving a high R-square value of about 0.97 based on a quantitative comparison of the breakthrough volume with other models. The simplified model can also simulate wormhole propagation for the reciprocal of the Damköhler number (1/Da) ranging from 0.001 to 1 with adequate accuracy. Sensitivity studies on the natural fracture parameters such as orientation, length, width, and density showed that higher fracture density, wider fracture aperture, longer fracture length, and orientation aligned with the direction of acid injection contribute to lower pore volume to breakthrough ratio but may not increase long-term acid stimulation efficiency. Also, the presence or absence of fractures in the matrix does not alter the dissolving patterns and optimum injection rate. This simple acid reactive-transport model can generate large training datasets for developing surrogate models in deep learning research. Finally, the FEniCS code in this paper is shared so future researchers can reproduce the results or extend the research work.

Abstract The motivation for constructing a thin-shell wormhole from a (2+1)-dimensional rotating black hole arises from the desire to study the effects of a nonminimally coupled scalar field in this particular spacetime. By investigating the behavior of such a field in the presence of rotation, we can gain insights into the interplay between gravity and scalar fields in lower-dimensional systems. Additionally, this construction allows us to explore potential connections between black hole physics and exotic phenomena like traversable wormholes. The radial perturbation around the equilibrium throat radius is considered to explore the stable configuration for specific values of physical parameters. Then, the equations of state, specifically the phantom-like and generalized Chaplygin gas model for exotic matter is used to conduct an extensive investigation into the stability of the counter-rotating thin-shell wormholes. Our results show that the presence of a scalar field enhances the stability of the counter-rotating thin-shell wormholes.

In this work, we present a review of Energy-Momentum Squared Gravity (EMSG)—more specifically, f (R , T μ ν T μ ν) gravity, where R represents the Ricci scalar and T μ ν denotes the energy-momentum tensor. The inclusion of quadratic contributions from the energy-momentum components has intriguing cosmological implications, particularly during the Universe's early epochs. These effects dominate under high-energy conditions, enabling EMSG to potentially address unresolved issues in General Relativity (GR), such as the initial singularity and aspects of big-bang nucleosynthesis in certain models. The theory's explicit non-minimal coupling between matter and geometry leads to the non-conservation of the energy-momentum tensor, which prompts the investigation of cosmological scenarios through the framework of irreversible thermodynamics of open systems. By employing this formalism, we interpret the energy-balance equations within EMSG from a thermodynamic perspective, viewing them as descriptions of irreversible matter creation processes. Since EMSG converges to GR in a vacuum and differences emerge only in the presence of an energy-momentum distribution, these distinctions become significant in high-curvature regions. Therefore, deviations from GR are expected to be pronounced in the dense cores of compact objects. This review delves into these facets of EMSG, highlighting its potential to shed light on some of the fundamental questions in modern cosmology and gravitational theory. [ABSTRACT FROM AUTHOR]

In developing his cosmological model of 1917, de Sitter theoretically predicted the phenomenon of cosmological redshift (the de Sitter effect), which he did long before the discovery of this phenomenon in observations. The de Sitter effect is gravitational by its nature, as it is due to differences between the coordinate systems of the observer and the distant source. However, the relationship between the redshift and distance derived from the de Sitter metric is at odds with observations, since this relationship is nonlinear (quadratic) for small redshifts, while the observed relationship between the same quantities is strictly linear. This paper discusses the possibility that cosmological redshift is gravitational by its nature, as in de Sitter's 1917 model. At the same time, here, as in de Sitter's model, an elliptical space is used, the main characteristic of which is the identification of its antipodal points. But, unlike de Sitter's model, here, in order to ensure strict linear dependence of the redshift on distance, the origin of the reference system is transferred to the observer's antipodal point. The Schwarzschild–de Sitter metric used in this model allows you to estimate the curvature of space from observational data. To achieve this, a theoretical Hubble diagram is built within the framework of the model with the Schwarzschild–de Sitter metric, which is compared with observations from the Pantheon+ catalogue of type Ia supernovae and the Amati catalogue of gamma-ray bursts in the redshift range of 0 < z < 8 . As a result of this comparison, we found that the lower estimate of the radius of curvature of space was quite large: 2.4 × 10 15 Mpc. This means that the observational data indicate a negligible curvature of space. [ABSTRACT FROM AUTHOR]

The Janis–Newman–Winicour spacetime corresponds to a static spherically symmetric solution of Einstein equations with the energy momentum tensor of a massless quintessence field. It is understood that the spacetime describes a naked singularity. The solution has two parameters, b and s. To our knowledge, the exact physical meaning of the two parameters is still unclear. In this paper, starting from the Janis–Newman–Winicour naked singularity solution, we first obtain a wormhole solution by a complex transformation. Then, letting the parameter s approach infinity, we obtain the well-known exponential wormhole solution. After that, we embed both the Janis–Newman–Winicour naked singularity and its wormhole counterpart in the background of a de Sitter or anti-de Sitter universe with the energy momentum tensor of massive quintessence and massive phantom fields, respectively. To our surprise, the resulting quintessence potential is actually the dilaton potential found by one of us. It indicates that, by modulating the parameters in the charged dilaton black hole solutions, we can obtain the Janis–Newman–Winicour solution. Furthermore, a charged wormhole solution is obtained by performing a complex transformation on the charged dilaton black hole solutions in the background of a de Sitter or anti-de Sitter universe. We eventually find that s is actually related to the coupling constant of the dilaton field to the Maxwell field and b is related to a negative mass for the dilaton black holes. A negative black hole mass is physically forbidden. Therefore, we conclude that the Janis–Newman–Winicour naked singularity solution is not physically allowed. [ABSTRACT FROM AUTHOR]

The motivation for constructing a thin-shell wormhole from a (2+1)-dimensional rotating black hole arises from the desire to study the effects of a nonminimally coupled scalar field in this particular spacetime. By investigating the behavior of such a field in the presence of rotation, we can gain insights into the interplay between gravity and scalar fields in lower-dimensional systems. Additionally, this construction allows us to explore potential connections between black hole physics and exotic phenomena like traversable wormholes. The radial perturbation around the equilibrium throat radius is considered to explore the stable configuration for specific values of physical parameters. Then, the equations of state, specifically the phantom-like and generalized Chaplygin gas model for exotic matter is used to conduct an extensive investigation into the stability of the counter-rotating thin-shell wormholes. Our results show that the presence of a scalar field enhances the stability of the counter-rotating thin-shell wormholes. [ABSTRACT FROM AUTHOR]

Science stands as the beacon of human ingenuity, illuminating pathways through the vast uncertainties of existence and exploring the frontiers of the universe. It challenges our understanding, propels our ambitions, and provides the essential frameworks for survival. This article explores the interplay between science, specifically physics, and the human quest for survival as depicted in Christopher Nolan's Interstellar. The film portrays a dystopian future where Earth's habitability is rapidly deteriorating, forcing humanity to look beyond the planet for survival. Central to this narrative is the application of advanced physics concepts like wormholes, black holes, and time dilation, since they serve as the critical mechanisms driving the plot and enabling humankind's hope for survival. By delving into these scientific principles, this article highlights how Interstellar reflects the fundamental role of physics in extending the boundaries of human existence and adaptability. It also examines the film's deeper philosophical questions about humanity's resilience, the nature of space-time, and the ethical repercussions of survival, eventually underscoring the extensive significance of science in shaping the future of human life. [ABSTRACT FROM AUTHOR]

Wormhole solutions, bridges that connect different parts of spacetime, were proposed early in the history of General Relativity. Soon after, it was shown that all wormholes violate classical energy conditions, which are non-negativity constraints on contractions of the stress–energy tensor. Since these conditions are violated by quantum fields, it was believed that wormholes can be constructed in the context of semiclassical gravity. But negative energies in quantum field theory are not without restriction: quantum energy inequalities (QEIs) control renormalized negative energies averaged over a geodesic. Thus, QEIs provide restrictions on the construction of wormholes. This work is a review of the relevant literature, thus focusing on results where QEIs restrict traversable wormholes. Both 'short' and 'long' (without causality violations) wormhole solutions in the context of semiclassical gravity are examined. A new result is presented on constraints on the Maldacena, Milekhin, and Popov 'long' wormhole from the recently derived doubled smeared null energy condition. [ABSTRACT FROM AUTHOR]

Is it possible for today's man to return to the historical past several centuries or millennia and find himself among his ancestors as shown in various science fiction films such as the cult British series "Outlander" when the main heroine enters the hollow of the tree and returns in the middle ages. Is it possible to travel into the future several centuries or millennia into the future as shown by Herbert George Wells in the science fiction novel Time machine or the French film "Les Visiteurs" when the heroes of the Middle Ages travel to the future. Are there parallel worlds or multiverses in which one day future generations will travel only with advanced technologies at the speed of light like in the cult TV series Wars or Dr.No? For now, these impossible feats are possible only on movies, but scientists like Albert Einstein, Nikola Tesla, and especially Everett Hughes, Stephen Hawking, theoretically explained the probability of such hypotheses. The concepts of time travel and parallel worlds are phenomena that are mutually related and interdependent both in literature and cinema, and in other scientific cultural-artistic or entertainment works. They complement and enhance each other because the phenomenon of time travel cannot be effected if there is no other world, even assuming that it is simply a return to the past or travel to the future. In this review, we will only focus on the phenomenon of time travel. This paper is part of the research dedicated to the project Time Travel and Parallel Worlds in Cinema integrated in my doctoral thesis with the same title. [ABSTRACT FROM AUTHOR]

The present work looks for the possible existence of static and spherically symmetric wormhole geometries in Rastall–Rainbow gravity. Since, the Rastall–Rainbow gravity model has been constructed with the combination of Rastall theory and the gravity's rainbow formalism. Taking advantage of the Karmarkar condition for embedding class one metrics, we solve the modified field equations analytically that describe wormholes for specific choice of redshift function. For specific parameter ranges, the solution represents a traversable wormhole that exhibits the violation of null energy condition and consequently the weak energy condition also. Furthermore, we focus on the wormhole stability via adiabatic sound velocity analysis. This model establishes a strong connection between two model parameters, namely, the Rastall parameters and the Rainbow functions, and how it affects the wormhole solution. [ABSTRACT FROM AUTHOR]

While modern computers are fast, there are still many practical problems that require even faster computers. It turns out that on the fundamental level, one of the main factors limiting computation speed is the fact that, according to modern physics, the speed of all processes is limited by the speed of light. Good news is that while the corresponding limitation is very severe in Euclidean geometry, it can be more relaxed in (at least some) non-Euclidean spaces, and, according to modern physics, the physical space is not Euclidean. The differences from Euclidean character are especially large on micro-level, where quantum effects need to be taken into account. To analyze how we can speed up computations, it is desirable to reconstruct the actual distance values – corresponding to all possible paths – from the values that we actually measure – which correspond only to macro-paths and thus, provide only the upper bound for the distance. In our previous papers – including our joint paper with Victor Selivanov – we provided an explicit formula for such a reconstruction. But for this formula to be useful, we need to analyze how algorithmic is this reconstructions. In this paper, we show that while in general, no reconstruction algorithm is possible, an algorithm is possible if we impose a lower limit on the distances between steps in a path. So, hopefully, this can help to eventually come up with faster computations. [ABSTRACT FROM AUTHOR]

In this paper, we explore the existence of wormholes in the context of f (R , T) gravity. The f (R , T) theory is a curvature-matter coupled modified gravity that depends on an arbitrary function of the Ricci scalar R and the trace of the stress-energy tensor T. In this work, we adopt two different choices for the matter Lagrangian density ( ℒ m = and ℒ m = p r ) and investigate the impact of each one on wormhole structure. By adequately specifying the redshift function and the shape function, we found a variety of exact wormhole solutions in the theory. Our finding indicates that for both classes of wormholes, the energy density is always positive throughout the spacetime, while the radial pressure is negative. This means exotic matter is necessary for the existence of wormholes in f (R , T) gravity. [ABSTRACT FROM AUTHOR]

This research work provides an exhaustive investigation of the viability of different coupled wormhole (WH) geometries with the relativistic matter configurations in the f (R , G , T) extended gravity framework. We consider a specific model in the context of f (R , G , T) -gravity for this purpose. Also, we assume a static spherically symmetric spacetime geometry and a unique distribution of matter with a set of shape functions (β (r)) for analyzing different energy conditions. In addition to this, we examined WH-models in the equilibrium scenario by employing anisotropic fluid. The corresponding results are obtained using numerical methods and then presented using different plots. In this case, f (R , G , T) gravity generates additional curvature quantities, which can be thought of as gravitational objects that maintain irregular WH-situations. Based on our findings, we conclude that in the absence of exotic matter, WH can exist in some specific regions of the parametric space using modified gravity model as f (R , G , T) = R + α R 2 + β G n + γ G ln (G) + λ T. [ABSTRACT FROM AUTHOR]

The main feature of elliptical space—the topological identification of its antipodal points—could be fundamental for understanding the nature of the cosmological redshift. The physical interpretation of the mathematical (topological) structure of elliptical space is made by using physical connections in the form of Einstein-Rosen bridges (also called "wormholes"). The Schwarzschild metric of these structures embedded into a dynamic (expanding) spacetime corresponds to McVittie's solution of Einstein's field equations. The cosmological redshift of spectral lines of remote sources in this metric is a combination of gravitational redshift and the time-dependent scale factor of the Friedmann-Lemaitre-Robertson-Walker metric. I compare calculated distance moduli of type-Ia supernovae, which are commonly regarded as "standard candles" in cosmology, with the observational data published in the catalogue "Pantheon+". The constraint based on these accurate data gives a much smaller expansion rate of the Universe than is currently assumed by modern cosmology, the major part of the cosmological redshift being gravitational by its nature. The estimated age of the Universe within the discussed model is 1.48 · 10 12 yr, which is more than two orders of magnitude larger than the age assumed by using the standard cosmological model parameters. [ABSTRACT FROM AUTHOR]

Morris and Thorne developed wormhole solutions in the late 1980s when they discovered a recipe that wormholes must follow for travelers to cross them safely. They describe exotic matter as satisfying −pr>ρ, where pr is the radial pressure and ρ is the energy density of the wormhole. This is a notable characteristic of the General Relativity Theory. The current article discusses traversable wormhole solutions in f(R,L,T)=R+αL+βT, with α and β are model parameters. The wormhole solutions presented here satisfy the metric constraints of traversability while remarkably avoiding the exotic matter condition, indicating that f(R,L,T) gravity wormholes can be filled with ordinary matter. The derived solutions for the shape function of the wormhole meet the required metric conditions. They exhibit behavior that is comparable to that of wormholes reported in earlier references, which is also the case for our solutions for the energy density of such objects.

Reprise Editor's Introduction

The existence of even the simplest magnetized wormholes may lead to observable consequences. In the case where both the wormhole and the magnetic field around its mouths are static and spherically symmetric, and gas in the region near the wormhole falls radially into it, the former's spectrum contains bright cyclotron or synchrotron lines due to the interaction of charged plasma particles with the magnetic field. At the same time, due to spherical symmetry, the radiation is non-polarized. The emission of this just-described exotic type (non-thermal, but non-polarized) may be a wormhole signature. Also, in this scenario, the formation of an accretion disk is still quite possible at some distance from the wormhole, but a monopole magnetic field could complicate this process and lead to the emergence of asymmetrical and one-sided relativistic jets. [ABSTRACT FROM AUTHOR]

In this paper, some Schwarzschild-like solutions in the framework of f (T) theory where T means the scalar tensor are reconstructed and analyzed in the context of some open problems like traversable wormholes and neutron starts mass limits. Like some authors, we search for the potentiality of the presence of traversable wormholes in the outer/inner regions halo of galaxies particularly the Milky Way galaxy by considering diagonal tetrads which support the Morris–Thorne metric. In such description where attention is attached to the energy density of dark matter present in the halo of spiral galaxies, a new dark matter density emerges in this work. The reconstructed density profile reveals the existence of traversable wormholes not only in the inner of the Milky Way galaxy but also in the both outer and inner of another galaxy smaller than the Milky Way galaxy. The use of Einasto density profile in this work makes it predict traversable wormholes in both outer and inner of the Milky Way galaxy. In the second part of this work, the non-diagonal tetrads describing the Schwarzschild metric are considered to solve the f (T) motion equations, where solutions describing neutron stars are provided. Several numerical analyses based on neutron stars mass are done and the obtained results give the best fit with observational data in the framework of neutron stars mass limit. [ABSTRACT FROM AUTHOR]

In this study, we investigate the relativistic dynamics of vector bosons within the context of rotating frames of negative curvature wormholes. We seek exact solutions for the fully-covariant vector boson equation, derived as an excited state of zitterbewegung. This equation encompasses a symmetric rank-two spinor, enabling the derivation of a non-perturbative second-order wave equation for the system under consideration. Our findings present exact results in two distinct scenarios. Notably, we demonstrate the adaptability of our results to massless vector bosons without compromising generality. The evolution of this system is shown to correlate with the angular frequency of the uniformly rotating reference frame and the curvature radius of the wormholes. Moreover, our results highlight that the interplay between the spin of the vector boson and the angular frequency of the rotating frame can give rise to real oscillation modes, particularly evident in excited states for massless vector bosons. Intriguingly, we note that the energy spectra obtained remain the same whether the wormhole is of hyperbolic or elliptic nature. [ABSTRACT FROM AUTHOR]

In this paper, we explore the physical properties and characteristics of static, spherically symmetric wormholes in the background of Rastall–Rainbow gravity. The Rastall–Rainbow gravity theory has recently been proposed as a combination of two theories, namely, the Rastall theory and the Rainbow description. We implemented noncommutativity by adopting two different distributions of energy density (Gaussian and Lorentzian) in the Morris and Thorne metric. We solve the field equations analytically and discuss all the properties of wormholes depending on the two model parameters. Notably, for specific parameter ranges, one can alleviate the violation of the WEC at the throat and its neighborhood. [ABSTRACT FROM AUTHOR]

We have conducted research on the presence of wormholes characterized by a logarithmic shape function within the framework of exponential f (R , T) gravity. This gravity model is defined as f (R , T) = R + 2 e β t , with β representing an arbitrary constant. We find that the logarithmic shape function serves as expected, providing all the necessary conditions for traversable and asymptotically flat wormholes. We have examined the solutions with three distinct sets of physical constraints placed on p r , p t and ρ. viz. Model-I: p r = k p t with k being variable dependent on r and p t = ω ρ with ω being EoS parameter, Model-II: p r = ω 1 ρ and p t = ω 2 ρ with ω 1 and ω 2 being EoS parameters, Model-III: Trace is zero i.e. T = 0 or ρ = p r + 2 p t i.e. f (R) gravity model. From Model-I, we have obtained a new parametrization for EoS parameter ω (r) and from Model-III, we have obtained a new form of shape function b (r) in f (R) gravity theory. [ABSTRACT FROM AUTHOR]

The flow‐induced dissolution of porous rocks governs many important subsurface processes and applications. Solute mixing, which determines pore‐scale concentration fields, is a key process that affects dissolution. Despite its importance, the effects of pore‐scale mixing on large‐scale dissolution patterns have not been investigated. Here, we use a pore network model to elucidate the mixing effects on macroscopic dissolution patterns and solute transport. We consider two mixing rules at pore intersections that represent two end members in terms of the mixing intensity. We observe that the mixing effect on dissolution is the strongest at moderate Damköhler number, when the reactive and advective time scales are comparable. This is the regime where wormholes spontaneously appear. Incomplete mixing is shown to enhance flow focusing at the tips of the dissolution channels, which results in thinner wormholes and shorter breakthrough times. These effects on passive solute transport are evident independent of initial network heterogeneity. Plain Language Summary: When a reactive fluid infiltrates the rock, the dissolution channels (wormholes) can spontaneously form, in which the flow and transport of reactant focus. The formation and growth of such channels is a complex phenomenon in which the processes taking place at the micro‐scale are strongly coupled with the macro‐scale patterns. One of these processes is the mixing of reactant‐saturated water at pore intersections. In this paper, we study how the intensity of the mixing process impacts the shapes and growth velocities of the dissolution channels. We find that when the mixing at pore intersections is relatively weak, the flow focuses more strongly in front of the wormhole tip, which reduces the width of the wormhole and leads to its faster propagation and early breakthrough. These effects are also evident from tracer breakthrough curves. Our findings contribute to the understanding of dissolution‐induced patterns, with implications to subsurface flow‐related processes such as karst formation and contaminant migration. Key Points: Mixing at pore intersections can have a major impact on macroscopic dissolution patterns and solute transportMixing effect is the strongest when reactive and advective time scales in the system are comparableMixing effect on dissolution increases as network heterogeneity decreases [ABSTRACT FROM AUTHOR]

The tunnel-like structures proposed by Morris and Thorne are explored in this study by using f (ℛ ,) framework. The solutions of static wormhole, supported by the matter possess van der Waals equation of state, are derived by two possible schemes. We have explored the shape function and energy conditions including null, weak, strong and dominant conditions. For this purpose, we used the equation of state p r = − α ρ 2 in first scheme and a numerical technique in second scheme. Also, the radius of the wormhole's throat is calculated, within which the energy conditions are satisfied. We have also deliberated the graphical illustrations of all the solutions. [ABSTRACT FROM AUTHOR]

There is an unavoidable association of traversability of wormholes to the violation of null energy condition which in turn indicates the presence of exotic or non-exotic matter in the wormhole geometry. The exotic matter possesses the negative energy that is required to sustain the wormhole. Recently studies are done to solve this problem so as to avoid the exotic matter. In this work, we attempt to find such solution in the framework of F (R , T) gravity where F (R , T) = R + 2 λ T , here R and T are Ricci scalar and trace of energy momentum tensor respectively, using the Yukawa–Casimir shape function. For Yukawa–Casimir wormhole, it is assumed that the exotic energy is sourced from the Casimir energy density. We have examined the energy conditions using Yukawa–Casimir shape function b (r) = 2 r 0 3 + r 0 2 3 r exp − μ r − r 0 , where μ is a positive mass scale. We have taken different values of μ to study the role of Yukawa–Casimir energy in formation of traversable wormholes. The equilibrium aspect of the model is also investigated with the help of TOV equation. [ABSTRACT FROM AUTHOR]

We study the properties of evolving wormholes able to exist in a closed Friedmann dust-filled universe and described by a particular branch of the well-known Lemaître–Tolman–Bondi solution to the Einstein equations and its generalization with a nonzero cosmological constant and an electromagnetic field. Most of the results are obtained with pure dust solutions. It is shown, in particular, that the lifetime of wormhole throats is much shorter than that of the whole wormhole region in the universe (which coincides with the lifetime of the universe as a whole), and that the density of matter near the boundary of the wormhole region is a few times smaller than the mean density of matter in the universe. Explicit examples of wormhole solutions and the corresponding numerical estimates are presented. The traversability of the wormhole under study is shown by a numerical analysis of radial null geodesics. [ABSTRACT FROM AUTHOR]

Using results of statistical field theory for systems with an anisotropic disorder, we present an analog model for Euclidean wormholes and topological fluctuation effects in a Riemannian space ℳ d . The contribution of wormholes and topological fluctuations to the Euclidean gravitational functional integral is modeled by quenched randomness defined in the ℝ d manifold. We obtain a disorder-averaged free energy by taking the average over all the realizations of the random fields. In the scenario of topology fluctuation, there appears a superposition of infinite branes that contribute to the physical quantities. All topology fluctuations can be understood as two distinct kinds of Euclidean wormholes: wormholes confined to one brane, and wormholes connecting different branes. [ABSTRACT FROM AUTHOR]

The various "defect wormholes" developed by Klinkhamer have recently attracted considerable attention—especially in view of the fact that the simplest example, the so-called "vacuum defect wormhole", was claimed to be an everywhere-vacuum everywhere-Ricci-flat exact solution to the Einstein equations. This claim has been conclusively refuted by Feng, and in the current article, we take a deeper look at exactly what goes wrong. The central issue is this: Although Klinkhamer's specific representation of the metric g a b is smooth ( C ∞ ), his inverse metric g a b is not even everywhere continuous ( C 0 ), being undefined at the wormhole throat. This situation implies that one should very carefully investigate curvature tensors at the throat using the Israel–Lanczos–Sen thin-shell formalism. Doing so reveals the presence of a delta-function energy-condition-violating thin shell of matter at the wormhole throat. The "defect wormholes" are thus revealed to be quite ordinary "cut-and-paste" thin-shell wormholes, but represented in a coordinate system that is unfortunately pathological at exactly the same place that all the interesting physics occurs. To help clarify the situation, we shall focus on the behavior of suitable coordinate invariants—the Ricci scalar, the eigenvalues of the mixed R a b Ricci tensor, and the eigenvalues of the mixed R a b c d Riemann tensor. [ABSTRACT FROM AUTHOR]

Regular black holes are often geodesically incomplete when their extensions to negative values of the radial coordinate are considered. Here, we propose to use the Simpson–Visser method of regularising a singular spacetime, and apply it to a regular solution that is geodesically incomplete, to construct a geodesically complete regular solution. Our method is generic, and can be used to cure geodesic incompleteness in any spherically symmetric static regular solution, so that the resulting solution is symmetric in the radial coordinate. As an example, we illustrate this procedure using a regular black hole solution with an asymptotic Minkowski core. We study the structure of the resulting metric, and show that it can represent a wormhole or a regular black hole with a single or double horizon per side of the throat. Further, we construct a source Lagrangian for which the geodesically complete spacetime is an exact solution of the Einstein equations, and show that this consists of a phantom scalar field and a nonlinear electromagnetic field. Finally, gravitational lensing properties of the geodesically complete spacetime are briefly studied. [ABSTRACT FROM AUTHOR]

This paper explores the existence of static wormholes in 4-Dimensional Einstein Gauss–Bonnet (4D EGB) gravity. We discuss some possibilities for constructing radial-dependent shape functions via different strategies to develop some non-conventional wormhole geometries by considering anisotropic matter sources. In this regard, we assume a specific form of the equation of state and investigate its effects on Gauss–Bonnet (GB) coupling parameter. Next, we impose a traceless condition on the anisotropic fluid distribution as well as radial-dependent energy density profile to explore wormhole geometries as separate cases. It is seen that the obtained results can be reduced into Morris–Throne wormholes for the zero value of GB-coupled parameter for anisotropic fluid distribution. Furthermore, we scrutinize flaring-out conditions and examine asymptotically flatness constraints for the existence of wormholes. Our analysis shows that the weak energy condition (WEC) is satisfied for a particular range by constraining GB-coupled parameter. We study the dynamics of GB-coupled parameter for both cases μ > 0 and μ < 0. It is concluded that wormhole solutions are possible for μ > 0 and, in some cases, μ < 0. The active gravitational mass of developed wormholes is calculated and plotted graphically. The wormhole geometry is discussed by plotting 2D and 3D embedding diagrams. In order to analyze the complexity of the system, we have plotted the complexity factor for each wormhole. [ABSTRACT FROM AUTHOR]

The paper explores the distribution of matter in thick disks around black holes and wormholes both numerically and analytically. Kerr and Lame metrics are considered, and exact analytical solutions are derived. The influence of toroidal magnetic fields on the structure of the thick disk is taken into account. Images of thin disks are constructed depending on the values of metric parameters. [ABSTRACT FROM AUTHOR]

A review of the development of our ideas about new forms of matter in the Universe is presented. [ABSTRACT FROM AUTHOR]

One of the most important issues in cosmology is the study of a series of hypothetical objects called wormholes. Recently, researchers have studied these hypothetical objects under different conditions. In this paper, we aim to evaluate the traversable wormhole according to a modified f (R) gravitational model, specifically − R 2 + a R 2 (1 − n) , from the perspective of two essential functions in wormhole structure: shape and redshift function. These hypothetical objects can solve Einstein's equations by tolerating the violation of null energy conditions (NEC). With respect to these concepts, we examine various energy conditions such as the NEC, weak energy condition (WEC), dominant energy condition (DEC) and strong energy condition (SEC) using radial pressure, tangential pressure and energy density obtained from the wormhole equations. Finally, we evaluate different energy conditions by plotting some figures and checking for satisfaction or violation. We will analyze the results and present the conclusions in tables. [ABSTRACT FROM AUTHOR]