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# Geometric Analysis and Partial Differential Equations Seminar

## July 12, 2013 @ 10:30 am - 11:30 pm

##### Speaker

Prof. Xiao Zhang (Chinese Academy of Sciences, Beijing China)

##### Title

The positive energy theorem for spacetimes with the positive cosmological constant

##### Abstract

The positive energy theorem plays a fundamental role in general relativity. It was firstly proved by Schoen-Yau using minimal surfaces and PDEs, and then by Witten using spinors in the case of zero cosmological constant. In this talk, we shall discuss the theorem when the cosmological constant is positive. This case seems to gain much more importance as the recent cosmological observations indicate that our universe has a positive cosmological constant.