Narrow Results

The paper investigates the static, non-commutative solutions of wormholes (WHs) that exhibit spherical symmetry. The study is conducted in the setting of modified Gauss–Bonnet gravity. Our investigation employs two methods: to construct a shape function using a viable $f(G)$ gravity model and to infer the $f(G)$ model through a specific shape function. We then carefully analyze the energy constraints for both methods. Our findings reveal the following results. For each value of $r$, the first technique provides a physically viable solution of WH related to the ordinary matter. The second approach has a feasible solution only when the values of $r$ are high. This study analyzes the complex procedure of the development of cosmic structures to demonstrate a connection between hypothetical and observed data.

This paper highlights a family of timeless universes connected by the same simple change of coordinates which allows to transfer between the two metrics involved in the description of each such universe. The first example can be called the simple-basic timeless universe. This universe allows one to create some other timeless universes, one of them being without matter, one in expansion and another one of the wormhole type. In all these universes, there are regions where classical physical time exists, but a global time coordinate indicating the temporal order of events does not exist. This happens because, in these universes, we can mathematically construct future oriented time-like loops and closed chains of future oriented time-like curves. The example of timeless expanding universe shows that time, in general, is not a consequence of space expansion.

In this paper, we study noncommutative static spherically symmetric wormhole solutions in the context of modified Gauss–Bonnet gravity. We explore these solutions either by assuming a viable $f(G)$ model to construct shape function or by specifying the shape function to deduce $f(G)$ model. The energy conditions are discussed for both types of wormholes. In the first case, we find a physically acceptable wormhole solution threaded by normal matter for all values of radial coordinate $r$ while the second case gives physical solution only for large values of $r$.

In this work, we investigate wormhole configurations described by a constant redshift function in Einstein-Cubic gravity (ECG). We derive analytical wormhole geometries by assuming a particular equation of state (EoS) and investigate the possibility that these solutions satisfy the standard energy conditions. We introduce exact asymptotically flat and anti-de Sitter (AdS) spacetimes that admit traversable wormholes. These solutions are obtained by imposing suitable values for the parameters of the theory so that the resulted geometries satisfy the weak energy condition (WEC) in the vicinity of the throat, due to the presence of higher-order curvature terms. Moreover, we find that AdS solutions satisfy the WEC throughout the spacetime. A description of the geodesic motion of time-like and null particles is presented for the obtained wormhole solutions. Also, using gravitational lensing effects, observational features of the wormhole structure are discussed.

This work aims to investigate the wormhole solutions in the background of $f(R,\phi ,X)$ theory of gravity, where $R$ is Ricci scalar, $\phi$ is scalar potential, and $X$ is the kinetic term. We consider spherically symmetric static space–time for exploring the wormhole geometry with anisotropic fluid. For our current analysis, we consider a particular equation of state parameter to study the behavior of traceless fluid and examine the physical behavior of energy density and pressure components. Furthermore, we also choose a particular shape function and explore the energy conditions. It can be noticed that energy conditions are violated for both shape functions. The violation of energy conditions indicates the existence of exotic matter and wormhole. Therefore, it can be concluded that our results are stable and realistic. The interesting feature of this work is to show two- and three-dimensional plotting for the analysis of wormhole geometry.

This paper investigates static spherically symmetric traversable wormhole (WH) solutions in $f({𝒢},T)$ gravity (${𝒢}$ and $T$ represent the Gauss–Bonnet invariant and trace of the energy–momentum tensor, respectively). We construct explicit expressions for ordinary matter by taking specific form of redshift function and $f({𝒢},T)$ model. To analyze the possible existence of wormholes, we consider anisotropic, isotropic, as well as barotropic matter distributions. The graphical analysis shows the violation of null energy condition for the effective energy–momentum tensor throughout the evolution while ordinary matter meets energy constraints in certain regions for each case of matter distribution. It is concluded that traversable WH solutions are physically acceptable in this theory.

This paper explores static spherically symmetric wormhole solutions in the galatic halo region for $f({𝒢},T)$ gravity (${𝒢}$ and $T$ represent the Gauss–Bonnet invariant and trace of the energy–momentum tensor, respectively). We formulate the explicit expressions for matter variables and evaluate wormhole solutions either specifying $f({𝒢},T)$ model to construct shape function or taking specific form of the shape function to determine $f({𝒢},T)$ model. It is found that null energy condition for the effective energy–momentum tensor is violated throughout the evolution in both cases while physically acceptable wormhole solutions exist only for a considered $f({𝒢},T)$ model.

This work provides some feasible regions for the existence of traversable wormhole geometries in modified $f({𝒢},T)$ gravity. For this purpose, three different matter contents have been studied with special emphasis on anisotropic fluid by considering a specific $f({𝒢},T)$ gravity power law model. It has been shown that the null energy conditions for the effective energy–momentum tensor are widely violated for the ordinary matter content. However, some small feasible regions to support the wormhole solutions have been noted. Furthermore, the stability of the anisotropic feasible regions for the wormhole solutions has been discussed. It is concluded that the wormhole geometries threaded by the ordinary matter actually exist and are well stable in $f({𝒢},T)$ gravity.

Rip cosmological models have been investigated in the framework of $f(T,{𝒯})$ theory of gravity, where $T$ denotes the torsion and ${𝒯}$ is the trace of the energy–momentum tensor. These phantom cosmological models revealed that at initial epoch a EoS parameter $\omega <-1$ tends asymptotically at late phase to $-1$$(\omega \to -1)$. On the other hand, Wormhole Solutions and Big Trip have been subject to an investigation. The wormhole throat radius $R(t)$ and the conditions to be satisfied to produce the Big Trip phenomenon have been discussed.

In this paper, Morris Thorne wormholes are considered in the context of $f(R)$ gravity. A shape function is defined as $b(r)=r_0(1-k)+k\frac{r_0^2}{r}$, where $k$ is constant. The equation of state is considered as $p_t=-\rho$ and $f(R)$ function is derived. The wormhole solutions are obtained and energy conditions are examined. Further, the $f(R)$ model is found to be consistent with local gravity tests and stability of cosmological perturbations and late-time de Sitter point. Cosmological evolution is also explored using Friedman-Robertson-Walker (FRW) metric in $f(R)$ gravity.