Scalar waves in a wormhole geometry (original) (raw)

ar X iv : g r-qc / 0 51 10 29 v 1 6 N ov 2 00 5 Scalar Waves in a Wormhole Topology

2008

Global monochromatic solutions of the scalar wave equation are obtained in flat wormholes of dimensions 2+1 and 3+1. The solutions are in the form of infinite series involving cylindirical and spherical wave functions and they are elucidated by the multiple scattering method. Explicit solutions for some limiting cases are illustrated as well. The results presented in this work constitute instances of solutions of the scalar wave equation in a spacetime admitting closed timelike curves.

Resonances in the transmission of massless scalar waves in a class of wormholes

Physical Review D, 1995

The propagation of massless, minimally coupled scalar waves in the curved backgrounds of a oneparameter family of wormhole geometries is investigated using numerical methods. The transmission coefBcient as a function of the energy of the scalar wave exhibits distinct resonances dependent on the value of the parameter which specifies the geometry.

Scalars on asymptotically locally AdS wormholes with mathcalR2\mathcal{R}^{2}mathcalR2 terms

Cornell University - arXiv, 2018

In this paper we study the propagation of a probe scalar on an asymptotically locally AdS wormhole solution of Einstein-Gauss-Bonnet theory in five dimensions. The radial coordinate ρ connects both asymptotic regions located at ρ → ±∞. The metric is characterized by a single integration constant ρ 0 and the wormhole throat is located at ρ = 0. In the region 0 < ρ < ρ 0 , both the gravitational pull as well as the centrifugal contributions to the geodesic motion point in the same direction and therefore they cannot balance. We explore the consequences of the existence of this region on the propagation of a scalar probe. The cases with ρ 0 = 0 as well as the limit ρ 0 → +∞ lead to exactly solvable differential eigenvalue problems, with shape-invariant potentials of the Rosen-Morse and Scarf family, respectively. Here, we numerically obtain the normal modes of a scalar field when ρ 0 = 0, with reflecting boundary conditions at both asymptotic regions. We also explore the effect of a non-minimal coupling between the scalar curvature and the scalar field. Remarkably, there is a particular value of the non-minimal coupling parameter that leads to fully resonant spectra in the limit of vanishing ρ 0 as well as when ρ 0 → +∞, for purely radial modes.

Rotating scalar field wormhole

Classical and Quantum Gravity, 2006

We derive an exact solution of the Einstein's equations with a scalar field stress-energy tensor with opposite-sign, and show that such a solution describes the inner region of a rotating wormhole. We also show that the non-rotating case of such a solution represents a static, asymptotically flat wormhole solution. We match the radial part of the rotating solution to the static one at both mouths, thus obtaining an analytic description for the asymptotic radial region of space-time. We explore some of the features of these solutions.

Wormholes supported by a kink-like configuration of a scalar field

Classical and Quantum Gravity, 2002

We study the problem of existence of static spherically symmetric wormholes supported by the kink-like configuration of a scalar field. With this aim we consider a self-consistent, real, nonlinear, nonminimally coupled scalar field φ in general relativity with the symmetry-breaking potential V (φ) possessing two minima. We classify all possible field configurations ruling out those of them for which wormhole solutions are impossible. Field configurations admitting wormholes are investigated numerically. Such the configurations represent a spherical domain wall localized near the wormhole throat.

Generic Three-Parameter Wormhole Solution in Einstein-Scalar Field Theory

Particles, 2021

An exact analytical, spherically symmetric, three-parametric wormhole solution has been found in the Einstein-scalar field theory, which covers the several well-known wormhole solutions. It is assumed that the scalar field is massless and depends on the radial coordinate only. The relation between the full contraction of the Ricci tensor and Ricci scalar has been found as RαβRαβ=R2. The derivation of the Einstein field equations have been explicitly shown, and the exact analytical solution has been found in terms of the three constants of integration. The several wormhole solutions have been extracted for the specific values of the parameters. In order to explore the physical meaning of the integration constants, the solution has been compared with the previously obtained results. The curvature scalar has been determined for all particular solutions. Finally, it is shown that the general solution describes naked singularity characterized by the mass, the scalar quantity and the throat.

New features of extended wormhole solutions in the scalar field gravity theories

Classical and Quantum Gravity, 2008

The present paper reports interesting new features that wormhole solutions in the scalar field gravity theory have. To demonstrate these, we obtain, by using a slightly modified form of the Matos-Núñez algorithm, an extended class of asymptotically flat wormhole solutions belonging to Einstein minimally coupled scalar field theory. Generally, solutions in these theories do not represent traversable wormholes due to the occurrence of curvature singularities. However, the Ellis I solution of the Einstein minimally coupled theory, when Wick rotated, yields Ellis class III solution, the latter representing a singularity-free traversable wormhole. We see that Ellis I and III are not essentially independent solutions. The Wick rotated seed solutions, extended by the algorithm, contain two new parameters a and δ. The effect of the parameter a on the geodesic motion of test particles reveals some remarkable features. By arguing for Sagnac effect in the extended Wick rotated solution, we find that the parameter a can indeed be interpreted as a rotation parameter of the wormhole. The analyses reported here have wider applicability in that they can very well be adopted in other theories, including in the string theory.

Scattering of electromagnetic waves by a traversable wormhole

Iranian Journal of Physics Research 5 (3), 135-144

Spin entropy production for particles with arbitrary spin moving in a curved spacetime is discussed. There is a Wigner rotation due to both the acceleration an the curvature, which causes an initial pure state to transform into a final mixed state. Depending on the spacetime characteristics, one may find paths on which there is no Wigner rotation and the state remains pure.

Scalar Fields as Sources for Wormholes and Regular Black Holes

Particles, 2018

We review nonsingular static, spherically symmetric solutions of general relativity with minimally coupled scalar fields. Considered are wormholes and regular black holes (BHs) without a center, including black universes (BHs with expanding cosmology beyond the horizon). Such configurations require a "ghost" field with negative kinetic energy K. Ghosts can be invisible under usual conditions if K < 0 only in strong-field region ("trapped ghost"), or they rapidly decay at large radii. Before discussing particular examples, some general results are presented, such as the necessity of anisotropic matter for asymptotically flat or AdS wormholes, no-hair and global structure theorems for BHs with scalar fields. The stability properties of scalar wormholes and regular BHs under spherical perturbations are discussed. It is stressed that the effective potential V eff for perturbations has universal shapes near generic wormhole throats (a positive pole regularizable by a Darboux transformation) and near transition surfaces from canonical to ghost scalar field behavior (a negative pole at which the perturbation finiteness requirement plays a stabilizing role). Positive poles of V eff emerging at "long throats" (with the radius r ≈ r 0 + const • x 2n , n > 1, x = 0 is the throat) may be regularized by repeated Darboux transformations for some values of n.

The Finslerian wormhole models

2016

We present models of wormhole under the Finslerian structure of spacetime. This is a sequel of our previous work (Eur Phys J 75:564, 2015) where we constructed a toy model for compact stars based on the Finslerian spacetime geometry. In the present investigation, a wide variety of solutions are obtained that explore wormhole geometry by considering different choices for the form function and energy density. The solutions, like the previous work, are revealed to be physically interesting and viable models for the explanation of wormholes as far as the background theory and literature are concerned.