Data & Time : 25 Sep. (Fri.), 3:00 pm
Place : R1029
Speaker : Hyun Seok Yang
Institute : CQUeST
Title : Gravitational Memory, BMS Supertranslations and Soft Theorems
Abstract : The transit of a gravitating radiation pulse past arrays of detectors stationed near future null infinity in the vacuum is considered. It is shown that the relative ositions and clock times of the detectors before and after the adiation transit differ by a BMS supertranslation. An explicit expression for the supertranslation in terms of moments of the radiation energy flux is given. The relative spatial displacement found for a pair of nearby detectors reproduces the well-known and potentially measurable gravitational memory effect. The displacement memory formula is shown to be equivalent to Weinberg’s formula for soft graviton production.