An international research team consisting of the Korea Astronomy and Space Science Institute, Kogakuin University, and Nagoya City University has conducted a detailed investigation of periodic lateral displacements observed in the jet launched from the supermassive black hole at the center of the giant elliptical galaxy M87. As a result, they found that these oscillations are not merely local fluctuations, but instead behave as “transverse waves” propagating downstream within the jet. Such waves may originate from activity in the vicinity of the black hole, or may be generated by instabilities that develop as the jet propagates. This discovery provides a new clue for understanding the physical processes occurring inside relativistic jets.