Episode 735 - Cosmic Conundrums

The fundamental relationship between physical rotation and magnetic states has remained a cornerstone of quantum and classical mechanics for over a century. In 1915, Albert Einstein and Wander Johannes de Haas demonstrated that altering the magnetization of a ferromagnetic material physically induces a macroscopic rotation. While this Einstein-de Haas effect established that electron spin couples directly to mechanical motion, the micro-mechanical reciprocal—specifically, how angular momentum transfers and conserves among collective atomic vibrations (phonons) within a solid lattice—remained an unverified theoretical prediction. ​On May 12, 2026, an international collaboration of physicists representing the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the Fritz Haber Institute of the Max Planck Society, alongside researchers from Berlin, Dresden, Jülich, and Eindhoven, published a study in Nature Physics addressing this theoretical gap. The research team, led by O. Minakova, C. Paiva, M. Frenzel, M. S. Spencer, J. M. Urban, C. Ringkamp, M. Wolf, G. Mussler, D. M. Juraschek, and S. F. Maehrlein, succeeded in directly observing and controlling angular momentum transfer between distinct lattice vibrations in a solid material.