The Field-Theoretic Approach in General Relativity and Other Metric Theories. A Review

Understand

GR and other metric theories of gravity are formulated with an arbitrary auxiliary curved background in a Lagrangian formalism.

• A new sketch of how to include spinor fields is included.
• Conserved quantities are obtained using Noether's theorem and expressed as divergences of antisymmetric densities, connecting local perturbations with quasi-local conserved quantities.
• The background's arbitrariness matches the so-called non-localizability of gravitational energy (infinity of localizations).