## Abstract

Gravity, and the puzzle regarding its energy, can be understood from a gauge theory perspective. Gravity, i.e., dynamical s-pacetime geometry, can be considered as a local gauge theory of the symmetry group of Minkowski spacetime: the Poincare group. The dynamical potentials of the Poincare gauge theory of gravity are the frame and the metric-compatible connection. The spacetime geometry has in general both curvature and torsion. Einstein's general relativity theory is a special case. Both local gauge freedom and energy are clarified via the Hamiltonian formulation. We have developed a covariant Hamiltonian formulation. The Hamiltonian boundary term gives covariant expressions for the quasi-local energy, momentum and angular momentum. A key feature is the necessity to choose on the boundary a non-dynamic reference. With a best matched reference one gets good quasi-local energy-momentum and angular momentum values.

Original language | English |
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Title of host publication | Memorial Volume for Yi-shi Duan |

Publisher | World Scientific Publishing Co. Pte Ltd |

Pages | 168-187 |

Number of pages | 20 |

ISBN (Electronic) | 9789813237278 |

ISBN (Print) | 9789813237261 |

State | Published - 5 Jan 2018 |