scholarly journals Quaternionic electrodynamics

2020 ◽  
Vol 35 (39) ◽  
pp. 2050327
Author(s):  
Sergio Giardino

We develop a quaternionic electrodynamics and show that it naturally supports the existence of magnetic monopoles. We obtained the field equations, the continuity equation, the electrodynamic force law, the Poynting vector, the energy conservation, and the stress-energy tensor. The formalism also enabled us to generalize the Dirac monopole and the charge quantization rule.

2015 ◽  
Vol 30 (35) ◽  
pp. 1550190 ◽  
Author(s):  
Tiberiu Harko ◽  
Francisco S. N. Lobo ◽  
M. K. Mak ◽  
Sergey V. Sushkov

Eddington-inspired Born–Infeld (EiBI) gravity is a recently proposed modified theory of gravity, based on the classic work of Eddington and Born–Infeld nonlinear electrodynamics. In this paper, we consider the possibility that wormhole geometries are sustained in EiBI gravity. We present the gravitational field equations for an anisotropic stress–energy tensor and consider the generic conditions, for the auxiliary metric, at the wormhole throat. In addition to this, we obtain an exact solution for an asymptotically flat wormhole.


2009 ◽  
Vol 24 (31) ◽  
pp. 2517-2530 ◽  
Author(s):  
JERZY MATYJASEK ◽  
DARIUSZ TRYNIECKI

The second-order term of the approximate stress–energy tensor of the quantized massive scalar field in the Bertotti–Robinson and Reissner–Nordström spacetimes is constructed within the framework of the Schwinger–DeWitt method. It is shown that although the Bertotti–Robinson geometry is a self-consistent solution of the (Λ = 0) semiclassical Einstein field equations with the source term given by the leading term of the renormalized stress–energy tensor, it does not remain so when the next-to-leading term is taken into account and requires the introduction of a cosmological term. The addition of the electric charge to the system does not change this behavior. The near horizon geometry of the extreme quantum-corrected Reissner–Nordström black hole is analyzed. It has the AdS2 ×S2 topology and the sum of the curvature radii of the two-dimensional submanifolds is proportional to the trace of the second-order term. It suggests that the "minimal" approximation should be constructed from the first two terms of the Schwinger–DeWitt expansion


2019 ◽  
pp. 59-65
Author(s):  
Steven Carlip

The “source” of gravity in the Einstein field equations is the stress-energy tensor. After a discussion of why gravitational mass should be part of a rank two tensor, this chapter derives the stress-energy tensor for a variety of types of matter: point particles, perfect fluids, scalar fields, and electromagnetism. The chapter discusses the relationship of differential and integral conservation laws, and introduces the problem of gravitational energy. It concludes with a discussion of one of the most remarkable results of general relativity, the fact that equations of motion for matter do not need to be introduced separately, but follow from the field equations.


2020 ◽  
Vol 35 (27) ◽  
pp. 2050222
Author(s):  
M. Sharif ◽  
Sana Saleem

The aim of this paper is to investigate the stability of Einstein static cosmos using anisotropic homogeneous perturbations in the background of [Formula: see text] theory in which [Formula: see text] and [Formula: see text] express the Ricci scalar and trace of the stress–energy tensor, respectively. To accomplish this work, we consider perfect fluid distribution and adopt small anisotropic perturbations in the scale factors and matter contents. We develop static and perturbed field equations that are simplified by using equation of state parameter. For the specific models of [Formula: see text] theory with conserved and non-conserved stress–energy tensor, the Einstein solutions are explored and their stability regions are analyzed graphically. We conclude that the static Einstein stable universe with anisotropic perturbations exists in this framework contrary to general relativity.


2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Hanno Bertle ◽  
Andrea Dei ◽  
Matthias R. Gaberdiel

Abstract The large N limit of symmetric orbifold theories was recently argued to have an AdS/CFT dual world-sheet description in terms of an sl(2, ℝ) WZW model. In previous work the world-sheet state corresponding to the symmetric orbifold stress-energy tensor was identified. We calculate certain 2- and 3-point functions of the corresponding vertex operator on the world-sheet, and demonstrate that these amplitudes reproduce exactly what one expects from the dual symmetric orbifold perspective.


1996 ◽  
Vol 11 (27) ◽  
pp. 2171-2177
Author(s):  
A.N. ALIEV

The electromagnetic perturbations propagating in the multiconical spacetime of N parallel cosmic strings are described. The expression for vacuum average of the stress-energy tensor is reduced to a form involving only zero-spin-weighted perturbation modes.


2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Ming-Zhi Chung ◽  
Yu-tin Huang ◽  
Jung-Wook Kim

Abstract In this paper, we demonstrate that at leading order in post Minkowskian (PM) expansion, the stress-energy tensor of Kerr-Newman black hole can be recovered to all orders in spin from three sets of minimal coupling: the electric and gravitational minimal coupling for higher-spin particles, and the “minimal coupling” for massive spin-2 decay. These couplings are uniquely defined from kinematic consideration alone. This is shown by extracting the classical piece of the one-loop stress-energy tensor form factor, which we provide a basis that is valid to all orders in spin. The 1 PM stress tensor, and the metric in the harmonic gauge, is then recovered from the classical spin limit of the form factor.


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