scholarly journals Traversable wormholes without exotic matter in multimetric repulsive gravity

2014 ◽  
Vol 89 (8) ◽  
Author(s):  
Manuel Hohmann
Keyword(s):  
Exotic Matter ◽  
Traversable Wormholes ◽  
Repulsive Gravity

scholarly journals TRAVERSABLE WORMHOLES IN A STRING CLOUD

2008 ◽  
Vol 17 (08) ◽  
pp. 1179-1196 ◽  
Author(s):  
MARTÍN G. RICHARTE ◽  
CLAUDIO SIMEONE
Keyword(s):  
Thin Shell ◽  
Dimensional Space ◽  
Space Time ◽  
Exotic Matter ◽  
Spherically Symmetric ◽  
Related Model ◽  
Traversable Wormholes ◽  
Dimensional Space Time ◽  
Thin Shell Wormholes ◽  
The Stability

We study spherically symmetric thin shell wormholes in a string cloud background in (3 + 1)-dimensional space–time. The amount of exotic matter required for the construction, the traversability and the stability of such wormholes under radial perturbations are analyzed as functions of the parameters of the model. In addition, in the appendices a nonperturbative approach to the dynamics and a possible extension of the analysis to a related model are briefly discussed.

scholarly journals Wormhole modeling in R2 gravity with linear trace term

2020 ◽  
Vol 35 (08) ◽  
pp. 2050045
Author(s):  
Nisha Godani ◽  
Gauranga C. Samanta
Keyword(s):  
General Relativity ◽  
General Theory ◽  
Significant Contribution ◽  
Shape Function ◽  
Exotic Matter ◽  
Geometric Configuration ◽  
Energy Conditions ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Traversable Wormholes

Morris and Thorne1 proposed traversable wormholes, hypothetical connecting tools, using the concept of Einstein’s general theory of relativity. In this paper, the modification of general relativity (in particular [Formula: see text] theory of gravity defined by Harko et al.2) is considered, to study the traversable wormhole solutions. The function [Formula: see text] is considered as [Formula: see text], where [Formula: see text] and [Formula: see text] are controlling parameters. The shape and redshift functions appearing in the metric of wormhole structure have significant contribution in the development of wormhole solutions. We have considered both variable and constant redshift functions with a logarithmic shape function. The energy conditions are examined, geometric configuration is analyzed and the radius of the throat is determined in order to have wormhole solutions in absence of exotic matter.

scholarly journals Wormhole modeling supported by non-exotic matter

2019 ◽  
Vol 34 (28) ◽  
pp. 1950224 ◽  
Author(s):  
Gauranga C. Samanta ◽  
Nisha Godani
Keyword(s):  
Shape Function ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Traversable Wormholes ◽  
Geometric Nature

In the present paper, the modeling of traversable wormholes, proposed by Morris and Thorne [Am. J. Phys. 56, 395 (1988)], is performed within the [Formula: see text] gravity with particular viable case [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text]. The energy conditions are analyzed using the shape function [Formula: see text] defined by Godani and Samanta [Int. J. Mod. Phys. D 28, 1950039 (2018)] and the geometric nature of wormholes is analyzed.

Charged traversable wormholes in f(R) gravity

2021 ◽  
pp. 2150098
Author(s):  
Nisha Godani ◽  
Gauranga C. Samanta
Keyword(s):  
Gravitational Lensing ◽  
Deflection Angle ◽  
Strong Field ◽  
Energy Condition ◽  
Weak Energy Condition ◽  
Exotic Matter ◽  
Field Limit ◽  
Traversable Wormholes ◽  
The Deflection Angle ◽  
Lensing Effect

This work is focused on the study of charged wormholes in the following two aspects: (i) to obtain exotic matter free effective charged wormhole solutions and (ii) to determine deflection angle for gravitational lensing effect. We have defined a novel redshift function, obtained wormhole solutions using the background of [Formula: see text] theory of gravity and found the regions obeying the weak energy condition. Further, the gravitational lensing effect is analyzed by determining the deflection angle in terms of strong field limit coefficients.

Modeling of traversable wormholes in exponential f(R,T) gravity

2021 ◽  
Author(s):  
Chanchal Chawla ◽  
Archana Dixit ◽  
Anirudh Pradhan
Keyword(s):  
Shape Function ◽  
Anisotropy Parameter ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Physical Parameters ◽  
Asymptotically Flat ◽  
Physical Constraints ◽  
Traversable Wormholes ◽  
Necessary Constraints ◽  
The Universe

In the present communication, we have studied the existence of wormholes described by a logarithmic shape function, in the exponential f(R, T) gravity given by f(R, T) = R + 2ξe^{ςt} where ξ and ς are arbitrary constants, under three different set of physical constraints. The logarithmic shape function is found to be well behaved satisfying all the necessary constraints for traversable and asymptotically flat wormholes. The obtained wormhole solutions are analyzed from the energy conditions for different values of involved physical constants. It has been observed that our proposed shape function for the exponential form of f(R, T) gravity, represents the existence of exotic matter with a standard violation of the NEC. Moreover, for the trace T=0 i.e. for the general relativity case with R being replaced by R+2, the wormhole geometry has been analyzed to prove the existence of exotic matter. Further, the behaviour of physical parameters such as the energy density ρ, the trace T, anisotropy parameter △ describing the geometry of the universe has been presented with the help of graphs.

Stable Morris Thorne wormholes supported by non-exotic matter

2021 ◽  
pp. 2150170
Author(s):  
Nisha Godani
Keyword(s):  
General Relativity ◽  
Gravity Model ◽  
Stability Condition ◽  
Modified Gravity ◽  
Shape Function ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Traversable Wormholes ◽  
The Stability ◽  
Metric Function

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.

scholarly journals Traversable wormholes in Einsteinian cubic gravity

2019 ◽  
Vol 35 (06) ◽  
pp. 2050017 ◽  
Author(s):  
Mohammad Reza Mehdizadeh ◽  
Amir Hadi Ziaie
Keyword(s):  
Equation Of State ◽  
Gravitational Lensing ◽  
Energy Condition ◽  
Higher Order ◽  
Energy Conditions ◽  
Geodesic Motion ◽  
De Sitter ◽  
Asymptotically Flat ◽  
Traversable Wormholes ◽  
Standard Energy

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.

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