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Outer boundary conditions for strongly and symmetric hyperbolic formulations of 3D Einstein's field equations with a live gauge condition are discussed. The boundary conditions have the property that they ensure constraint propagation and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Olivier Sarbach , Manuel Tiglio

The potential flow of two-dimensional ideal incompressible fluid with a free surface is studied. Using the theory of conformal mappings and Hamiltonian formalism allows us to derive exact equations of surface evolution. Simple form of the…

Fluid Dynamics · Physics 2012-06-12 V. E. Zakharov , A. I. Dyachenko

This paper formulates time-dependent, force-free, degenerate electrodynamics as a hyperbolic system of conservation laws. It is shown that this system has four characteristic modes, a pair of fast waves propagating with the speed of light…

Astrophysics · Physics 2009-11-07 S. S. Komissarov

We study the constraint equations for the Einstein-scalar field system on compact manifolds. Using the conformal method we reformulate these equations as a determined system of nonlinear partial differential equations. By introducing a new…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yvonne Choquet-Bruhat , James Isenberg , Daniel Pollack

We investigate the finite time stability property of one-dimensional nonautonomous initial boundary value problems for linear decoupled hyperbolic systems with nonlinear boundary conditions. We establish sufficient and necessary conditions…

Analysis of PDEs · Mathematics 2025-12-10 Irina Kmit

In this paper we present a new approach for studying the dynamics of spatially inhomogeneous cosmological models with one spatial degree of freedom. By introducing suitable scale-invariant dependent variables we write the evolution…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Henk van Elst , Claes Uggla , John Wainwright

Open effective field theories provide a systematic framework for describing physical systems interacting with an environment whose microscopic details are unknown, unobservable, or uncalculable. A basic step in constructing any effective…

High Energy Physics - Theory · Physics 2026-05-25 Enrica Lausdei , Enrico Pajer

In this paper, we establish a necessary and sufficient stability condition for a class of two coupled first-order linear hyperbolic partial differential equations. Through a backstepping transform, the problem is reformulated as a stability…

Optimization and Control · Mathematics 2025-03-24 Ismaïla Balogoun , Jean Auriol , Islam Boussaada , Guilherme Mazanti

We propose and study a one-dimensional $2\times 2$ hyperbolic Eulerian system with local relaxation from critical threshold phenomena perspective. The system features dynamic transition between strictly and weakly hyperbolic. For different…

Analysis of PDEs · Mathematics 2020-12-15 Manas Bhatnagar , Hailiang Liu

We present three-dimensional simulations of Einstein equations implementing a symmetric hyperbolic system of equations with dynamical lapse. The numerical implementation makes use of techniques that guarantee linear numerical stability for…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Manuel Tiglio , Luis Lehner , David Neilsen

We consider one-dimensional, locally finite interacting particle systems with two conservation laws. The models have a family of stationary measures with product structure and we assume the existence of a uniform bound on the inverse of the…

Probability · Mathematics 2007-05-23 Benedek Valko

In this article, it is shown how the extended conformal Einstein field equations and a gauge based on the properties of conformal geodesics can be used to analyse the non-linear stability of de Sitter-like spacetimes with spatial sections…

General Relativity and Quantum Cosmology · Physics 2024-08-09 Marica Minucci , Juan Antonio Valiente Kroon

The tetrad-based equations for vacuum gravity published by Estabrook, Robinson, and Wahlquist are simplified and adapted for numerical relativity. We show that the evolution equations as partial differential equations for the Ricci rotation…

General Relativity and Quantum Cosmology · Physics 2014-11-17 L. T. Buchman , J. M. Bardeen

Einstein's field equations for timelike self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Martin Goliath , Ulf S Nilsson , Claes Uggla

A general covariant extension of Einstein's field equations is considered with a view to Numerical Relativity applications. The basic variables are taken to be the metric tensor and an additional four-vector. The extended field equations,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. Bona , T. Ledvinka , C. Palenzuela , M. Zacek

In this paper, the hyperbolic Anderson equation generated by a time-dependent Gaussian noise is under investigation in two fronts: The solvability and large-$t$ asymptotics. The investigation leads to a necessary and sufficient condition…

Probability · Mathematics 2025-10-03 Xia Chen

A perturbative quantum theory of the two Killing vector reduction of Einstein gravity is constructed. Although the reduced theory inherits from the full one the lack of standard perturbative renormalizability, we show that strict cutoff…

High Energy Physics - Theory · Physics 2007-05-23 P. Forgacs , M. Niedermaier

We consider the Einstein-Boltzmann system for massless particles in the Bianchi I space-time with scattering cross-sections in a certain range of soft potentials. We assume that the space-time has an initial conformal gauge singularity and…

General Relativity and Quantum Cosmology · Physics 2024-08-21 Ho Lee , Ernesto Nungesser , John Stalker , Paul Tod

By employing the Bianchi identities for the Riemann tensor in conjunction with the Einstein equations, we construct a first order symmetric hyperbolic system for the evolution part of the Cauchy problem of general relativity. In this…

General Relativity and Quantum Cosmology · Physics 2012-08-27 Arlen Anderson , Yvonne Choquet-Bruhat , James W. York,

Studies of new hyperbolic systems for the Einstein evolution equations show that the ``slicing density'' $\alpha(t,x)$ can be freely specified while the lapse $N = \alpha g^{1/2}$ cannot. Implementation of this small change in the…

General Relativity and Quantum Cosmology · Physics 2012-08-27 James W. York,