The HZDR-Fritz Haber experiment used intense terahertz pulses to excite circular lattice vibrations in bismuth selenide, then tracked transfer via a second ultrafast probe—directly imaging angular momentum flow for the first time. This peer-reviewed Nature Physics study (no sample size or crystal dimensions reported in coverage) exposes an Umklapp-like reversal where 1+1 yields -1, driven by lattice rotational symmetry rather than dissipation. Original reporting underplays Bi2Se3's topological insulator properties, which amplify phonon-magnon coupling and link to prior spintronics work (e.g., 2015 Einstein-de Haas revival experiments in PRL and 2022 phonon angular momentum papers in Nature Communications). The reversal challenges textbook conservation narratives by showing crystal symmetry alone can invert direction, opening routes to symmetry-engineered spin control missed in standard magnetism texts. Limitations include cryogenic or high-field conditions likely required for coherence, plus restriction to this specific material; broader applicability remains untested. This reframes magnetism origins as symmetry-tunable rather than purely exchange-driven.