TianjinA beam of light moved upstream without spending energy.
The result could give physicists a new way to steer quantum light in devices.
The swimmer attracted the river but the river repelled the swimmer, a non-reciprocal force that breaks action-reaction, Yi Hu’s team found.
Earlier upstream motion in light fluids relied on vortex recoil, said Mathias Albert of Côte d’Azur University.
Hu’s team next plans experiments with several swimmers and finer control of their motion.
Sources: New Scientist