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From a covariant Hamiltonian formulation, using symplectic ideas, we obtain covariant quasilocal energy-momentum boundary expressions for general gravity theories. The expressions depend upon which variables are fixed on the boundary, a…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Chiang-Mei Chen , James M. Nester , Roh Suan Tung

Traditional approaches to energy-momentum localization led to reference frame dependent pseudotensors. The more modern idea is quasilocal energy-momentum. We take a Hamiltonian approach. The Hamiltonian boundary term gives not only the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Chia-Chen Chang , James M. Nester , Chiang-Mei Chen

From a covariant Hamiltonian formulation, by using symplectic ideas, we obtain certain covariant boundary expressions for the quasilocal quantities of general relativity and other geometric gravity theories. The contribution from each of…

General Relativity and Quantum Cosmology · Physics 2014-11-17 C. M. Chen , J. M. Nester

The Hamiltonian for a gravitating region includes a boundary term which determines not only the quasi-local values but also, via the boundary variation principle, the boundary conditions. Using our covariant Hamiltonian formalism, we found…

General Relativity and Quantum Cosmology · Physics 2013-05-29 Chiang-Mei Chen , James M. Nester , Roh-Suan Tung

The various roles of boundary terms in the gravitational Lagrangian and Hamiltonian are explored. A symplectic Hamiltonian-boundary-term approach is ideally suited for a large class of quasilocal energy-momentum expressions for general…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Chiang-Mei Chen , James M. Nester

The Hamiltonian for dynamic geometry generates the evolution of a spatial region along a vector field. It includes a boundary term which determines both the value of the Hamiltonian and the boundary conditions. The value gives the…

General Relativity and Quantum Cosmology · Physics 2019-02-27 Gang Sun , Chiang-Mei Chen , Jian-Liang Liu , James M. Nester

Early energy-momentum investigations for gravitating systems gave reference frame dependent pseudotensors; later the quasilocal idea was developed. Quasilocal energy-momentum can be determined by the Hamiltonian boundary term, which also…

General Relativity and Quantum Cosmology · Physics 2009-10-31 C. C. Chang , J. M. Nester , C. M. Chen

We construct a Hamiltonian formulation of quasilocal general relativity using an extended phase space that includes boundary coordinates as configuration variables. This allows us to use Hamiltonian methods to derive an expression for the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ivan S. Booth , Stephen Fairhurst

The Hamiltonian for dynamic geometry generates the evolution of a spatial region along a vector field. It includes a boundary term which determines both the value of the Hamiltonian and the boundary conditions. The value gives the…

General Relativity and Quantum Cosmology · Physics 2012-10-24 James M. Nester , Chiang-Mei Chen , Jian-Liang Liu , Gang Sun

The Hamiltonian for physical systems and dynamic geometry generates the evolution of a spatial region along a vector field. It includes a boundary term which not only determines the value of the Hamiltonian, but also, via the boundary term…

General Relativity and Quantum Cosmology · Physics 2013-07-08 Chiang-Mei Chen , Jian-Liang Liu , James M. Nester , Gang Sun

I modify the quasilocal energy formalism of Brown and York into a purely Hamiltonian form. As part of the reformulation, I remove their restriction that the time evolution of the boundary of the spacetime be orthogonal to the leaves of the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ivan S. Booth

A quasi-local energy for Einstein's general relativity is defined by the value of the preferred boundary term in the covariant Hamiltonian formalism. The boundary term depends upon a choice of reference and a time-like displacement vector…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Jian-Liang Liu , Chiang-Mei Chen , James M Nester

The boundary term of the gravitational Hamiltonian can be used to give the values of the quasi-local quantities as long as one can provide a suitable evolution vector field and an appropriate reference. On the two-surface boundary of a…

General Relativity and Quantum Cosmology · Physics 2013-07-04 Gang Sun , Chiang-Mei Chen , Jian-Liang Liu , James M. Nester

The specification of energy for gravitating systems has been an unsettled issue since Einstein proposed his pseudotensor. It is now understood that energy-momentum is \emph{quasi-local} (associated with a closed 2-surface). Here we consider…

General Relativity and Quantum Cosmology · Physics 2018-11-15 Chiang-Mei Chen , Jian-Liang Liu , James M. Nester

Recently Brown and York have devised a new method for defining quasilocal energy in general relativity. Their method yields expressions for the quasilocal energy and momentum surface densities associated with the two-boundary of a spacelike…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Stephen Lau

The M$\o$ller tetrad gravitational energy-momentum expression was recently evaluated for a small vacuum region using orthonormal frames adapted to Riemann normal coordinates. However the result was not proportional to the Bel-Robinson…

General Relativity and Quantum Cosmology · Physics 2008-09-24 Lau Loi So

This paper presents a complete set of quasilocal densities which describe the stress-energy-momentum content of the gravitational field and which are built with Ashtekar variables. The densities are defined on a two-surface $B$ which bounds…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Stephen R. Lau

The energy of gravitating systems has been an issue since Einstein proposed general relativity: considered to be ill defined, having no proper local density. Energy-momentum is now regarded as \emph{quasi-local} (associated with a closed…

General Relativity and Quantum Cosmology · Physics 2018-11-15 Chiang-Mei Chen , Jian-Liang Liu , James M. Nester

The quasilocal energy of gravitational and matter fields in a spatially bounded region is obtained by employing a Hamilton-Jacobi analysis of the action functional. First, a surface stress-energy-momentum tensor is defined by the functional…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. David Brown , James W. York

In general relativity, quasi-local energy-momentum expressions have been constructed from various formulae. However, Newtonian theory of gravity gives a well known and an unique quasi-local mass expression (surface integration). Since…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yu-Huei Wu , Chih-Hung Wang
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