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It is proposed that the propagation of light in disordered photonic lattices can be harnessed as a random projection that preserves distances between a set of projected vectors. This mapping is enabled by the complex evolution matrix of a…

Optics · Physics 2021-10-01 Mohammad-Ali Miri

A linear singularly perturbed convection-diffusion problem with characteristic layers is considered in three dimensions. Sharp bounds for the associated Green's function and its derivatives are established in the $L_1$ norm. The dependence…

Numerical Analysis · Mathematics 2015-03-19 S. Franz , N. Kopteva

The collapse of marginally bound, inhomogeneous, pressureless (dust) matter, in spherical symmetry, is considered. The starting point is not, in this case, the integration of the Einstein equations from some suitable initial conditions.…

General Relativity and Quantum Cosmology · Physics 2018-04-27 Ramon Lapiedra , Juan Antonio Morales-Lladosa

In this article, we continue our investigation on how the electromagnetic waves propagate in the Friedman-Lemaitre-Robertson-Walker spacetime. Unlike the standard approach, which relies on null geodesics and geometric optics approximation,…

General Relativity and Quantum Cosmology · Physics 2025-02-18 Denitsa Staicova , Michail Stoilov

Light propagation through turbulence produces speckles, whose ensemble behavior is typically characterized by snapshot intensity statistics. Here, we track the spatiotemporal evolution of individual speckles and quantify fragmentation,…

Optics · Physics 2025-11-12 Travis M. Crumpton , Luat T. Vuong

We analyze gravitational lensing in a matched Kottler spacetime with cosmological constant $\Lambda$, where a uniform-density fluid sphere described by the interior Kottler solution is smoothly joined to the exterior Kottler region. We…

General Relativity and Quantum Cosmology · Physics 2026-05-29 Mourad Guenouche

We develop a model-independent approach to lagrangian perturbation theory for the large scale structure of the universe. We focus on the displacement field for dark matter particles, and derive its most general structure without assuming a…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-27 Marco Marinucci , Kevin Pardede , Massimo Pietroni

A synoptic view on the long-established theory of light propagation in crystalline dielectrics is presented, providing a new exact solution for the microscopic local electromagnetic field thus disclosing the role of the divergence-free…

Optics · Physics 2018-08-03 Marius Dommermuth , Nils Schopohl

In the context of f(R) theories of gravity, we study the cosmological evolution of scalar perturbations by using a completely general procedure. We find that the exact fourth-order differential equation for the matter density perturbations…

Astrophysics · Physics 2015-05-13 A. de la Cruz-Dombriz , A. Dobado , A. L. Maroto

According to the separate universe conjecture, spherically symmetric sub-regions in an isotropic universe behave like mini-universes with their own cosmological parameters. This is an excellent approximation in both Newtonian and general…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-14 Gábor Rácz , László Dobos , Róbert Beck , István Szapudi , István Csabai

In this paper, we propose a new method to use the strong lensing data sets to constrain a cosmological model. By taking the ratio…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-05 Nannan Wang , Lixin Xu

Inspired by the fully non-linear Geodesic Light-Cone (GLC) gauge, we consider its analogous set of coordinates which describes the unperturbed Universe. Given this starting point, we then build a cosmological perturbation theory on top of…

General Relativity and Quantum Cosmology · Physics 2021-02-15 Giuseppe Fanizza , Giovanni Marozzi , Matheus Medeiros , Gloria Schiaffino

We present a new approach to calculating the statistical distributions for magnification, shear, and rotation of images of cosmological sources due to gravitational lensing. In this approach one specifies an underlying Robertson-Walker…

Astrophysics · Physics 2016-08-25 Daniel E. Holz , Robert M. Wald

We give a pedagogical review of a covariant and fully non-perturbative approach to study nonlinear perturbations in cosmology. In the first part, devoted to cosmological fluids, we define a nonlinear extension of the uniform-density…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 David Langlois , Filippo Vernizzi

A quantum theory of dispersion for an inhomogeneous solid is obtained, from a starting point of multipolar coupled atoms interacting with an electromagnetic field. The dispersion relations obtained are equivalent to the standard classical…

Quantum Physics · Physics 2009-10-31 P. D. Drummond , M. Hillery

Spatio-temporal imaging of light propagation is very important in photonics because it provides the most direct tool available to study the interaction between light and its host environment. Sub-ps time resolution is needed to investigate…

Optics · Physics 2016-06-17 Lorenzo Pattelli , Romolo Savo , Matteo Burresi , Diederik S. Wiersma

{Using two different approaches, we study imaging in the strong lens regime taking into account the effects of plasmatic environments on light propagation. First, we extend the use of a perturbative approach that allows us to quickly and…

General Relativity and Quantum Cosmology · Physics 2023-05-24 Gabriel Crisnejo , Emanuel Gallo , Ezequiel Boero , Osvaldo M. Moreschi

We study the diffusion of classical hard-core particles in disordered lattices within the formalism of a quantum spin representation. This analogy enables an exact treatment of non-instantaneous correlation functions at finite particle…

Statistical Mechanics · Physics 2009-10-31 M. D. Grynberg , R. B. Stinchcombe

The concept of local symmetry is a powerful tool in predicting complex transport phenomena in aperiodic media. A nonlocal continuity formalism reveals how local symmetries are encoded into the dynamics of light propagation in discrete…

We investigate linear matter density perturbations in models of structure formation with causal seeds. Under the fluid approximation, we obtain the analytic solutions using Green-function technique. Some incorrect solutions in the…

Astrophysics · Physics 2007-05-23 Jiun-Huei Proty Wu