scholarly journals Light propagation and optical scalars in torsion theories of gravity

2019 ◽  
Vol 34 (04) ◽  
pp. 1950029
Author(s):  
Siamak Akhshabi
Keyword(s):  
Gravitational Lensing ◽  
Light Propagation ◽  
Raychaudhuri Equation ◽  
Angular Diameter Distance ◽  
Propagation Of Light ◽  
Light Rays ◽  
Theories Of Gravity ◽  
Torsion Theories ◽  
Basic Equations ◽  
Gauge Theory Of Gravity

We investigate the propagation of light rays and evolution of optical scalars in gauge theories of gravity where torsion is present. Recently, the modified Raychaudhuri equation in the presence of torsion has been derived. We use this result to derive the basic equations of geometric optics for several different interesting solutions of the Poincaré gauge theory of gravity. The results show that the focusing effects for neighboring light rays will be different than general relativity. This in turn has practical consequences in the study of gravitational lensing effects and also in determining the angular diameter distance for cosmological objects.

scholarly journals Cosmological Parameter Survey Using the Gravitational Lensing Method

2001 ◽  
Vol 18 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Premana W. Premadi ◽  
Hugo Martel ◽  
Richard Matzner ◽  
Toshifumi Futamase
Keyword(s):  
Gravitational Lensing ◽  
Light Propagation ◽  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Angular Size ◽  
Hubble Constant ◽  
Density Parameter ◽  
Multiple Imaging ◽  
Light Rays ◽  
Insight Into

AbstractUsing a multiple-lens plane algorithm, we study light propagation in inhomogeneous universes for 43 different COBE-normalized Cold Dark Matter models, with various values of the density parameter Ω0, cosmological constant λ0, Hubble constant H0, and rms density fluctuation σ8.We performed a total of 3798 experiments, each experiment consisting of propagating a square beam of angular size 21.9″ 21.9″ composed of 116 281 light rays from the observer up to redshift z = 3. These experiments provide statistics of the magnification, shear, and multiple imaging of distant sources. The results of these experiments might be compared with observations, and eventually help constrain the possible values of the cosmological parameters. Additionally, they provide insight into the gravitational lensing process and its complex relationship with the various cosmological parameters.

scholarly journals Metamaterials mimic the black holes: the effects of charge and rotation on the optical properties

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
S H Hendi ◽  
Z S Taghadomi ◽  
A Ghasempour Ardakani
Keyword(s):  
Black Holes ◽  
Optical Properties ◽  
Light Propagation ◽  
Transformation Optics ◽  
Two Dimensional ◽  
Propagation Of Light ◽  
Analogue Gravity ◽  
Light Rays ◽  
Optical Limit ◽  
Dimensional Simulation

Abstract Motivated by the investigation of a black hole’s properties in the lab, some interesting subjects such as analogue gravity and transformation optics are generated. In this paper, we look for analogies between the geometry of a gravitating system and the optical medium. In addition, we recognize that appropriate two-dimensional metamaterials can be used to mimic the propagation of light in the curved spacetimes and behave like black holes which are incident with light rays in the equatorial plane. The resemblance of metamaterials with Kerr and Reissner–Nordström spacetimes is studied. Finally, we compare the results of two-dimensional simulation for light propagation in the corresponding two-dimensional metamaterials with those obtained from the geometrical optical limit.

scholarly journals An energy conservative hp-scheme for light propagation using Liouville’s equation for geometrical optics

2020 ◽  
Vol 238 ◽  
pp. 02005
Author(s):  
Robert A.M. van Gestel ◽  
Martijn J.H. Anthonissen ◽  
Jan H.M. ten Thije Boonkkamp ◽  
Wilbert L. IJzerman
Keyword(s):  
Optical System ◽  
Light Propagation ◽  
Energy Propagation ◽  
Conservation Of Energy ◽  
Adaptive Scheme ◽  
Propagation Of Light ◽  
Light Rays ◽  
Liouville’S Equation ◽  
Full Domain ◽  
Space Description

In this contribution an alternative method to standard forward ray-tracing is briefly outlined. The method is based on a phase-space description of light propagating through an optical system. The propagation of light rays are governed by Hamilton’s equations. Conservation of energy and étendue for a beam of light, allow us to derive a Liouville’s equation for the energy propagation through an optical system. Liouville’s equation is solved numerically using an hp-adaptive scheme, which for a smooth refractive index field is energy conservative. A proper treatment of optical interfaces ensures that the scheme is energy conservative over the full domain.

scholarly journals Вычислительный эксперимент по моделированию распространения света в волокнистой профилированной структуре

2020 ◽  
pp. 50-57
Author(s):  
V. V. Savchenko ◽  
M. A. Savchenko
Keyword(s):  
Ray Tracing ◽  
Light Propagation ◽  
Short Note ◽  
Fiber Structure ◽  
Propagation Of Light ◽  
Light Rays ◽  
Tracing Algorithm ◽  
The Given ◽  
System Characteristics ◽  
Fiber Sample

Many studies show that profiled structures are the source of attaining desired system characteristics in industrial or other applications. In this short note, we continue considering proposed recently by us the profiled structure such as a beach umbrella based on the principles of origami design. To demonstrate the optical properties of the given model, a developed recursive ray tracing algorithm is used to simulate the propagation of light rays through the modelled paper fiber sample. In this paper, modeling light propagation through a porous structure using ray tracing technique is presented and results of modeling light propagation in a profiled structure with respect to simulated light propagation in fiber structure are discussed. Во многих работах указывается, что использование профилированных структур позволяет получить характеристики материала, необходимые для его применения в промышленности и других областях. В этой небольшой статье мы продолжаем рассматривать предложенную нами недавно профилированную структуру в виде пляжного зонта, основанную на принципах дизайна оригами. Для демонстрации оптических свойств данной модели используется разработанный алгоритм рекурсивной трассировки лучей для моделирования распространения световых лучей через смоделированный образец бумажного волокна. В этой статье представлено моделирование распространения света через пористую структуру с использованием техники трассировки лучей, а также обсуждаются результаты моделирования распространения света в профилированной структуре в сравнении с моделированным распространением света в волокнистой структуре.

scholarly journals Testing Cosmogonic Models With Gravitational Lensing

1996 ◽  
Vol 173 ◽  
pp. 65-70 ◽  
Author(s):  
Joachim Wambsganss ◽  
Renyue Cen ◽  
Jeremiah P. Ostriker ◽  
Edwin L. Turner
Keyword(s):  
Gravitational Lensing ◽  
Three Dimensional ◽  
Model Universe ◽  
Propagation Of Light ◽  
Light Rays ◽  
Non Linear

Gravitational lensing provides a strict test of cosmogonic models. We use fully non-linear numerical propagation of light rays through a model universe with inhomogeneities derived from a particular cosmogonic model, i.e. three-dimensional lensing simulations, to study its lensing properties. As a first example we present results for the standard CDM scenario. The lensing test for this model predicts that we should have seen far more widely split quasar images than have been found.

scholarly journals Numerical methods for General Relativistic particles

2018 ◽  
Vol 14 (S342) ◽  
pp. 19-23
Author(s):  
Fabio Bacchini ◽  
Bart Ripperda ◽  
Alexander Y. Chen ◽  
Lorenzo Sironi
Keyword(s):  
Numerical Methods ◽  
Gravitational Lensing ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Numerical Algorithms ◽  
Relativistic Effects ◽  
Compact Objects ◽  
Light Rays ◽  
Massive Particles ◽  
External Forces

AbstractWe present recent developments on numerical algorithms for computing photon and particle trajectories in the surrounding of compact objects. Strong gravity around neutron stars or black holes causes relativistic effects on the motion of massive particles and distorts light rays due to gravitational lensing. Efficient numerical methods are required for solving the equations of motion and compute i) the black hole shadow obtained by tracing light rays from the object to a distant observer, and ii) obtain information on the dynamics of the plasma at the microscopic scale. Here, we present generalized algorithms capable of simulating ensembles of photons or massive particles in any spacetime, with the option of including external forces. The coupling of these tools with GRMHD simulations is the key point for obtaining insight on the complex dynamics of accretion disks and jets and for comparing simulations with upcoming observational results from the Event Horizon Telescope.

scholarly journals Light Propagation through Nanophotonics Wormholes

Universe ◽  
2018 ◽  
Vol 4 (12) ◽  
pp. 137 ◽  
Author(s):  
Carlos Sabín
Keyword(s):  
Light Propagation ◽  
State Of The Art ◽  
Curved Space ◽  
Traversable Wormhole ◽  
Propagation Of Light ◽  
Phase And Group Velocities ◽  
Spatial Shape ◽  
Group Velocities

We consider the propagation of light along a 3D nanophotonic structure with the spatial shape of a spacetime containing a traversable wormhole. We show that waves experience significant changes of phase and group velocities when propagating along this curved space. This experiment can be realized with state-of-the-art nanophotonics technology.

A genesis of special relativity

2015 ◽  
Vol 24 (10) ◽  
pp. 1530024
Author(s):  
Valérie Messager ◽  
Christophe Letellier
Keyword(s):  
Special Relativity ◽  
19Th Century ◽  
Maxwell Equations ◽  
Light Propagation ◽  
Principle Of Relativity ◽  
Light Rays ◽  
Optical Phenomena ◽  
Light Particles ◽  
The 19Th Century ◽  
The Waves

The genesis of special relativity is intimately related to the development of the theory of light propagation. When optical phenomena were described, there are typically two kinds of theories: (i) One based on light rays and light particles and (ii) one considering the light as waves. When diffraction and refraction were experimentally discovered, light propagation became more often described in terms of waves. Nevertheless, when attempts were made to explain how light was propagated, it was nearly always in terms of a corpuscular theory combined with an ether, a subtle medium supporting the waves. Consequently, most of the theories from Newton's to those developed in the 19th century were dual and required the existence of an ether. We therefore used the ether as our Ariadne thread for explaining how the principle of relativity became generalized to the so-called Maxwell equations around the 1900's. Our aim is more to describe how the successive ideas were developed and interconnected than framing the context in which these ideas arose.

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