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We present a simplified version of the lowest-order embedded point mass gravitational lens theory and then make the extension of this theory to any embedded transparent lens. Embedding a lens effectively reduces the gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-17 Ronald Kantowski , Bin Chen , Xinyu Dai

In this geometrical approach to gravitational lensing theory, we apply the Gauss-Bonnet theorem to the optical metric of a lens, modelled as a static, spherically symmetric, perfect non-relativistic fluid, in the weak deflection limit. We…

General Relativity and Quantum Cosmology · Physics 2008-12-18 G W Gibbons , M C Werner

Fermat's principle is fully generalized to the case where a smooth interface separates two cone structures -- Lorentz-Finsler lightcones -- representing wave propagation in a potentially inhomogeneous, anisotropic, time-dependent and…

Differential Geometry · Mathematics 2025-10-01 Miguel Ángel Javaloyes , Steen Markvorsen , Enrique Pendás-Recondo , Miguel Sánchez

The mathematical theory of gravitational lensing has revealed many generic and global properties. Beginning with multiple imaging, we review Morse-theoretic image counting formulas and lower bound results, and complex-algebraic upper bounds…

Astrophysics of Galaxies · Physics 2014-11-20 A. O. Petters , M. C. Werner

Building on the results of previous work, we demonstrate how matter fields are incorporated into the general linear frame approach to general relativity. When considering the Maxwell one-form field, we find that the system that leads…

General Relativity and Quantum Cosmology · Physics 2015-06-25 M. A. Clayton

Even when used to describe the same phenomenon, equations, graphics and words each give different perspectives and lead to complementary insights. The basic elements of strong gravitational lensing are introduced here favoring words and…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-30 Paul L. Schechter , Jeremy D. Schnittman

Using the linearized theory of general relativity, the gravitomagnetic analogue of the Barnett effect is derived. Further theoretical and experimental investigation is recommended, due to the expected macroscopic values of the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. J. de Matos , M. Tajmar

We analyzed the influence of static gravitational field on the vacuum and proposed the concept of inhomogeneous vacuum. According to the corresponding Fermat's principle in the general relativity, we derived a graded refractive index of…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Xing-Hao Ye , Qiang Lin

We offer a concise and direct way to derive the bending angle of light (i.e. as generally called, gravitational lensing), while light grazes a star, through the approach suggested earlier by the first author, which is fundamentally based on…

General Physics · Physics 2014-01-15 Tolga Yarman , Alexander Kholmetskii , Metin Arik

The theory of gravitational lensing has revealed many generic and fundamental properties of compact objects like black holes and wormholes. In this article, we utilize a recent formulation to compute the quantum effects on the deflection…

General Relativity and Quantum Cosmology · Physics 2018-01-11 Kimet Jusufi , Farook Rahaman , Ayan Banerjee

Interactions incorporating the vacuum polarization effects in curved backgrounds modify the null cone structure in such a way that the photon trajectories would not be the space-time geodesics anymore. The gravitational birefringence…

General Relativity and Quantum Cosmology · Physics 2008-11-26 N. Ahmadi , S. Khoeini-Moghaddam , M. Nouri-Zonoz

The present work shows that through a suitable change of variables relativistic dynamics can be mapped to light propagation in a non-homogeneous medium. A particle's trajectory through the modified space-time is thus formally equivalent to…

Optics · Physics 2007-05-23 J. B. Almeida

We first define what we mean by gravitational lensing equations in a general space-time. A set of exact relations are then derived that can be used as the gravitational lens equations in all physical situations. The caveat is that into…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Simonetta Frittelli , Ezra T. Newman

The contribution of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's Principle. The findings are in agreement with recent results…

Astrophysics · Physics 2008-12-18 Mustapha Ishak

This study aims to investigate the strong gravitational lensing effects in $f(T)$ gravity. We present the theoretical analytic expressions for the lensing effects in $f(T)$ gravity, including deflection angle, magnification, and time delay.…

General Relativity and Quantum Cosmology · Physics 2024-01-12 Xinyue Jiang , Xin Ren , Zhao Li , Yi-Fu Cai , Xinzhong Er

In this paper we investigate a complex symmetric generalization of general relativity and in particular we investigate its linearized field equations. We begin by reviewing some basic definitions and structures in Moffat's symmetric complex…

General Relativity and Quantum Cosmology · Physics 2009-09-22 Joakim Munkhammar

Fermat's principle applied to a flat metric in the plane yields the phase of a Bessel function in the periodic domain for a constant index of refraction. Gravitational forces cause the index of refraction to vary and lead to a modified…

Mathematical Physics · Physics 2016-11-15 B. H. Lavenda

We describe local light-ray rotation in terms of complex refractive indices. We show that Fermat's principle holds, and we derive an extended Snell's law. The change in the angle of a light ray with respect to the normal to a…

Optics · Physics 2009-01-29 Bhuvanesh Sundar , Alasdair C. Hamilton , Johannes Courtial

Linearized general relativity admits a formulation in terms of gravitoelectric and gravitomagnetic fields that closely parallels the description of the electromagnetic field by Maxwell's equations. For steady mass currents, this formalism…

General Relativity and Quantum Cosmology · Physics 2010-07-01 John Swain

In general relativity the fermions are treated from the perspective of the gauged Lorentz group and by introducing the corresponding gauge fields the spin connection. This procedure is intimately related to the so-called "vielbein"…

General Relativity and Quantum Cosmology · Physics 2020-04-23 Renata Jora