Yang's Gravitational Theory

Yang's pure space equations generalize Einstein's gravitational equations, while coming from gauge theory. We study these equations from a number of vantage points: summarizing the work done previously, comparing them with the Einstein equations and investigating their properties. In particular, the initial value problem is discussed and a number of results are presented for these equations with common energy-momentum tensors.     

General Relativity on a Null Surface: Hamiltonian Formulation in the Teleparallel Geometry

The Hamiltonian formulation of generalrelativity on a null surface is established in theteleparallel geometry. No particular conditions on thetetrads are imposed, like the time gauge condition. Bymeans of a 3 + 1 decomposition the resultingHamiltonian arises as a completely constrained system.However, it is structurally different from the standardArnowitt–Deser–Misner (adm) typeformulation. In this geometrical framework the basic fieldquantities are tetrads that transform under the globalSO(3, 1) and the torsion tensor.