In each volume of the journal General Relativity and Gravitation (GRG), a few papers are marked as “Editor’s Choice”. The primary criteria is original, high-quality research that is of wide interest within the community. This recent article deserves special attention:
Chiang-Mei Chen, Jian-Liang Liu, James M. Nester,
“Quasi-local energy from a Minkowski reference”
https://doi.org/10.1007/s10714-018-2484-z
Abstract:
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 quasi-local (associated with a closed 2-surface). Here we consider quasi-local proposals (including pseudotensors) in the Lagrangian–Noether–Hamiltonian formulations. There are two ambiguities: (1) there are many possible expressions, (2) they depend on some non-dynamical structure, e.g., a reference frame. The Hamiltonian approach gives a handle on both problems. The Hamiltonian perspective helped us to make a remarkable discovery: with an isometric Minkowski reference a large class of expressions—namely all those that agree with the Einstein pseudotensor’s Freud superpotential to linear order—give a common quasi-local energy value. Moreover, with a best-matched reference on the boundary this is the Wang–Yau mass value.
Please, browse all Editor’s Choice articles at:
https://www.springer.com/gp/livingreviews/relativity/grg-editors-choice
Frank Schulz
Publishing Editor GRG