Light can actually travel freely through a messy 2D environment that physicists thought would trap it forever.
April 29, 2026
Original Paper
Delocalization transition for light in two dimensions
arXiv · 2604.22919
The Takeaway
A long-held belief in physics states that any amount of disorder in a two-dimensional space will eventually stop light from moving. New research into 2D waveguides shows that this is not always true and that a delocalization transition can occur. Based on the density of atoms in the waveguide, light can suddenly break free and move across the system. This challenges the common sense of wave physics and shows that disorder does not always equal a dead end. This discovery will help engineers design more reliable optical communications networks and advanced light-based chips.
From the abstract
Common belief, confirmed by existing experiments, is that arbitrarily weak disorder should lead to spatial localization of eigenmodes of scalar wave equations when wave propagation is two-dimensional (2D). We predict that contrary to this belief, a localization-delocalization transition can take place for light scattered by two-level atoms placed at random positions in the middle plane of a parallel-plate 2D waveguide fed by its fundamental transverse-magnetic (TM) mode (electric field polarized