**4 May 2021***Current trends in gravitation Seminar*

Location: **University Oldenburg - Online **

When: 4.5.2021, 16:15 h**Speaker**: Carla Cederbaum (University TÃ¼bingen)

**Title**: On the center of mass in General Relativity

Abstract: In many situations in Newtonian gravity, understanding the motion of the center of mass of a system is key to understanding the general "trend" of the motion of the system. It is thus desirable to also devise a notion of center of mass with similar properties in General Relativity. However, while the definition of the center of mass via the mass density is straightforward in Newtonian gravity, there is a priori no definitive corresponding notion in general relativity. We will take geometric approach to defining the center of mass of a relativistic system in the spirit of a fundamental result by Huisken and Yau from 1996. I will then relate this approach to the standard ADM-approach. After introducing and relating these approaches, I will discuss the analytic, geometric, and physical issues they have. I will then present a new approach (joint work with Anna Sakovich) that remedies (most of) these issues.