Josephson junction formed in the wormhole space-time from the analysis of the critical temperature of BEC

In this study, we consider a gas in the Morris–Thorne traversable wormhole space-time, and analyze the critical temperature of the Bose-Einstein condensate in the vicinity of its throat. Our results show that it is equal to zero. Then, from this result, we point out that a state analogous to the Josephson junction is always formed at any temperature in the vicinity of its throat. This is of interest as a gravitational phenomenology. Of course, there is the problem of the exotic matter, but we perform this work without treating it.

Generalised Ellis–Bronnikov wormholes embedded in warped braneworld background and energy conditions

Ellis–Bronnikov (EB) wormholes require violation of null energy conditions at the ‘throat’. This problem was cured by a simple modification of the ‘shape function’, which introduces a new parameter $$m\ge 2$$ m ≥ 2 ($$m=2$$ m = 2 corresponds to the EB model). This leads to a generalised (GEB) version. In this work, we consider a model where the GEB wormhole geometry is embedded in a five dimensional warped background. We studied the status of all the energy conditions in detail for both EB and GEB embedding. We present our results analytically (wherever possible) and graphically. Remarkably, the presence of decaying warp factor leads to satisfaction of weak energy conditions even for the EB geometry, while the status of all the other energy conditions are improved compared to the four dimensional scenario. Besides inventing a new way to avoid the presence of exotic matter, in order to form a wormhole passage, our work reveals yet another advantage of having a warped extra dimension.

Charged thin-shell wormholes with quintessence effects

This work studies the theoretical construction of charged quintessence thin-shell wormholes using Israel thin-shell approach. The stability of these wormhole solutions is investigated by taking linear, logarithmic and Chaplygin gas models as a constituent of exotic matter at thin-shell. The presence of wormhole stability regions particularly relies on the physically justifiable values of charge and quintessence parameter. It is noted that the increasing value of charge seems as an effective component for stable regions while the rise in negativity of the quintessence parameter gives more stable wormhole configurations.

Schwarzschild-like Wormholes in Asymptotically Safe Gravity

In this paper, we analyze the Schwarzschild-like wormhole in the Asymptotically Safe Gravity(ASG) scenario. The ASG corrections are implemented via renormalization group methods, which, as consequence, provides a new tensor Xμν as a source to improved field equations, and promotes the Newton’s constant into a running coupling constant. In particular, we check whether the radial energy conditions are satisfied and compare with the results obtained from the usual theory. We show that only in the particular case of the wormhole being asymptotically flat(Schwarzschild Wormholes) that the radial energy conditions are satisfied at the throat, depending on the chosen values for its radius r0. In contrast, in the general Schwarzschild-like case, there is no possibility of the energy conditions being satisfied nearby the throat, as in the usual case. After that, we calculate the radial state parameter, ω(r), in r0, in order to verify what type of cosmologic matter is allowed at the wormhole throat, and we show that in both cases there is the possibility of the presence of exotic matter, phantom or quintessence-like matter. Finally, we give the ω(r) solutions for all regions of space. Interestingly, we find that Schwarzschild-like Wormholes with excess of solid angle of the sphere in the asymptotic limit have the possibility of having non-exotic matter as source for certain values of the radial coordinate r. Furthermore, it was observed that quantum gravity corrections due the ASG necessarily imply regions with phantom-like matter, both for Schwarzschild and for Schwarzschild-like wormholes. This reinforces the supposition that a phantom fluid is always present for wormholes in this context.

Accounting for exotic matter and the extreme radial tension in Morris–Thorne wormholes of embedding class one

The embedding of a curved spacetime in a higher-dimensional flat spacetime has continued to be a topic of interest in the general theory of relativity, as exemplified by the induced-matter theory. This paper deals with spacetimes of embedding class one, i.e., spacetimes that can be embedded in a five-dimensional flat spacetime. Einstein’s theory allows the fifth dimension to be either spacelike or timelike. By assuming the latter, this paper addresses two fundamental issues concerning Morris–Thorne wormholes, the origin of exotic matter and the frequently inexplicable enormous radial tension at the throat.

Computing the temporal intervals by making a Throne-Morris wormhole from a Kerr black hole in the context of f(R,T) gravity

In the paper we will proceed towards taking the larger root of and make it equal to zero to remove the event horizon of a Kerr black hole (BH) in Boyer-Lindquist coordinates with a prevalent ring type singularity that can be smoothen by a tunneling approach of a spherinder thereby proceeding safely towards the Cauchy horizon with the deduced intervals computed in detail for the time travel in the Throne-Morris wormhole (WH) approach under gravity without the presence of any exotic matter at the WH mouth thereby preserving the asymptotically solutions of flaring out conditions and mouth opening during the course of the journey through the Einstein-Rosen bridge. An approach has been organized in the paper in which not only time travel is possible without exotic matter but also time travel is flexible to past and future in the Einstein’s universe by eliminating all sorts of paradoxes by spatial sheath through 2D approach of temporal dimensions.

Stable Morris Thorne wormholes supported by non-exotic matter

The present work is focused on the study of traversable wormholes, proposed by Morris and Thorne [Wormholes in spacetime and their use for interstellar travel: A tool for teaching general relativity, Am. J. Phys. 56 (1988) 395], using the background of modified gravity. It is performed by using the models: I. [Formula: see text], II. [Formula: see text] and III. [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] are constants. The Model I belongs to the theory of [Formula: see text] gravity, Model II belongs to the theory of [Formula: see text] gravity and Model III is a combination of Models I and II. These functions have been taken into account for the exploration of wormhole solutions. The shape function, a wormhole metric function, is newly defined which satisfies the flare out condition. Further, the stability condition and energy conditions, namely null, weak and dominant energy conditions, have been examined with respect to each model.

Automatic enhancement in 6D supergravity and F-theory models

We observe that in many F-theory models, tuning a specific gauge group G and matter content M under certain circumstances leads to an automatic enhancement to a larger gauge group G′ ⊃ G and matter content M′ ⊃ M. We propose that this is true for any theory G, M whenever there exists a containing theory G′, M′ that cannot be Higgsed down to G, M. We give a number of examples including non-Higgsable gauge factors, nonabelian gauge factors, abelian gauge factors, and exotic matter. In each of these cases, tuning an F-theory model with the desired features produces either an enhancement or an inconsistency, often when the associated anomaly coefficient becomes too large. This principle applies to a variety of models in the apparent 6D supergravity swampland, including some of the simplest cases with U(1) and SU(N) gauge groups and generic matter, as well as infinite families of U(1) models with higher charges presented in the prior literature, potentially ruling out all these apparent swampland theories.

Thin-shell wormhole from ABGB–de Sitter black holes

A thin shell wormhole is constructed utilizing the cut and paste technique from ABGB–de Sitter black hole derived by Matyjasek et al. The surface stress localized at the wormhole throat is determined using Darmois–Israel formalism. We examine the attractive and repulsive nature of the thin shell wormhole on which cosmological constant [Formula: see text] has a significant effect. For the fixed values of charge [Formula: see text] and mass [Formula: see text], the attractiveness of the wormhole decreases with increasing [Formula: see text]. We calculate the total amount of exotic matter in the shell, which is not much affected by [Formula: see text]. For the construction of the wormhole in de Sitter universe, the regular black holes have to be heavily charged with a light mass to minimize the amount of required exotic matter. The stability of the wormhole solution is explored by considering a general equation of state in the form of linear perturbation. The stability regions are shown in the figures.