题目：Bondi-Sachs Spacetimes and the Bondi Energy 

报告人：张晓 教授

（中科院数学与系统科学研究院数学研究所，广西大学广西数学研究中心）

Abstract：

   Bondi-Sachs spacetimes were originally introduced by Bondi for axi-symmetric spacetimes, and generalized by Sachs to general asymptotically flat spacetimes for the zero cosmological constant. In this framework, Bondi defined the Bondi energy-momentum at null infinity, which represents the rest energy of spacetimes after the loss due to gravitational radiation. In this talk, we shall discuss, for zero cosmological constant, whether the Bondi energy is nonnegative? How the Bondi energy-momentum relates to the ADM energy-momentum defined at spatial infinity? We shall also discuss the natural boundary condition and the peeling property when the cosmological constant is nonzero. The talk is based on some joint works with W-l. Huang, Yau and F. Xie. 

时间：2019年12月23日（周一）下午16:00-17:00

地点：565net必赢客户端本部教二627教室

联系人：沈伟明，王越

欢迎全体师生积极参加！