Light sometimes appears to be “dragged” by the motion of the medium through which it is traveling. This phenomenon, referred to as “light dragging,” is typically imperceptible when light is traveling in most widely available materials, as the movement is significantly slower than the speed of light. So far, it has thus proved difficult to observe in experimental settings.

Researchers at the University of Toulouse, University of California-Los Angeles (UCLA), University of Paris-Saclay and Princeton University recently observed a specific type of light dragging known as image rotation in a plasma-based system.

Their observation, outlined in a paper published in Physical Review Letters, was made using magnetohydrodynamic (MHD) waves that propagate in a magnetized plasma, known as Alfvén waves.