毛普健  副教授学术报告

Title: Supertranslation in the bulk for generic spacetime

Speaker: Pujian Mao (毛普健)

Affiliation: Tianjin University（天津大学）

Time: 10:00-11:00 am, Friday, 15th May, 2026 (UTC+8, Beijing Time)

Venue: Room 1502, Shing-Tung Yau Center, Sipailou Campus of Southeast University（东南大学四牌楼校区丘成桐中心1502室）

Inviter: Yunfeng Jiang（江云峰）

Abstract

Supertranslations are usually defined as asymptotic symmetries associated with spacetime boundaries, such as null infinity and black hole horizons. We show that supertranslations admit a natural, coordinate-independent extension into the bulk of spacetime, realized as transitions between families of null hypersurfaces. This construction applies to generic spacetimes in arbitrary dimensions and unifies the realizations of supertranslations at null infinity and black hole horizons. The bulk supertranslation is connected to boundary supertranslation by characteristic flows. Within this framework, the gravitational wave memory effect corresponds to a shift of null hypersurfaces in the bulk. As explicit examples, we compute bulk supertranslations in Minkowski spacetime in arbitrary dimensions and in four-dimensional Schwarzschild spacetime, where we uncover a novel curvature-induced memory effect with observable consequences for light propagation.

Speaker

毛普健，天津大学副教授，研究方向为渐近对称性在引力与规范理论中的应用。2009年、2012年于兰州大学分别获得学士、硕士学位，2016年9月于比利时布鲁塞尔自由大学获得理学博士学位，随后于中科院高能物理研究所从事博士后研究。2018年7月加入天津大学工作至今。