Recently, spherically symmetric, static wormholes supported by exotic dust and a radial magnetic field have been derived and argued to be stable with respect to linear radial fluctuations. In this report we point out that these wormholes are unstable due to the formation of shell-crossing singularities when the nonlinearities of the theory are taken into account.
In this work we construct traversable wormholes geometries in the framework of the complexity factor. We provide the redshift function of a Casimir traversable wormhole which, in combination with a non--vanishing complexity factor, leads to a traversable wormhole with a minimum amount of exotic matter. The shape function and the embedding diagram are shown and discussed. The tidal accelerations and the time required to get through the wormholes are estimated.
A fundamental property of Morris-Thorne wormholes is the so-called flare-out condition that automatically results in a violation of the null energy condition (NEC) in classical general relativity. By contrast, in $f(R)$ modified gravity, the material threading the wormhole may actually satisfy the NEC, while, at the same time, the effective stress-energy tensor arising from the modified theory violates the NEC, thereby sustaining the wormhole. It is shown in this paper that noncommutative geometry, an offshoot of string theory, can be viewed as a special case of $f(R)$ gravity and can therefor…
It is well known that phantom energy, which is characterized by the equation of state $p=ωρ$, $ω<-1$, can support Morris-Thorne wormholes since it leads to a violation of the null energy condition. The purpose of this note is to show that the converse is also true in the following sense: for a typical shape function, the equation of state of exotic matter in the vicinity of the throat is given by $p_r=ωρ$, $ω<-1$, where $p_r$ is the radial pressure. Some implications thereof are also considered.
It is generally believed that wormholes are supported by exotic matter violating Null Energy Condition (NEC). However, various studies of wormhole geometries under Lovelock theories of gravity have reported existence of wormhole supported by matter satisfying NEC. Being inspired by these results, we explore the possibility of the existence of wormhole supported by normal quark matter in third order Lovelock gravity theory. Well known MIT Bag Model Equation of state is chosen for describing the quark matter. Taking physically acceptable approximations, we solve the field equations for shape fun…
In the present paper, we investigate wormholes in 4D-Einstein-Gauss-Bonnet gravity without the requirement of exotic matters. We have taken the radial dependent red-shift function $ϕ=\ln \left( {\frac {r_{0}}{r}}+1 \right)$ and shape function $b(r)={\frac{r_{0}\ln(r+1)}{\ln({r_0}+1)}}$ as well as anisotropic matter sources through equation of state (EoS) $p_r(r) = ωρ(r)$. We examine the energy conditions, flaring out condition, throat condition and anisotropic parameter. The volume integral quantifier is also analyzed to validate the existence and stability of the WH solution. We find, for -ve…
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 a…
Abstract This short paper investigates the harmonic behavior of a general-relativistic thin-shell wormhole supported by a particular type of exotic fluid. The exotic fluid obeys a never-studied-before metric-dependent equation of state. This equation of state is tailored such that the wormhole's throat undergoes a harmonic-like behavior before damping to an equilibrium radius. Eventually, the mirror-symmetric Schwarzschild thin-shell wormhole is studied in this framework as an example.
In this work we analyze traversable wormhole solutions in the linear form of $f\left(R,T\right)=R+λT$ gravity satisfying the Null, Weak, Strong, and Dominant Energy Conditions (NEC, WEC, SEC, and DEC respectively) for the entire spacetime. These solutions are obtained via a fully analytical parameter space analysis of the free parameters of the wormhole model, namely the exponents controlling the degree of the redshift and shape functions, the radius of the wormhole throat $r_0$, the value of the redshift function at the throat $ζ_0$, and the coupling parameter $λ$. Bounds on these free parame…
