EN
Ray splitting is a universal phenomenon that occurs in all wave systems with sharp interfaces. Quantum implications of ray splitting are: (i) the importance of non-Newtonian orbits for the density of states in the semiclassical limit, (ii) ray-splitting corrections to the average density of states and (iii) the need to include non-Newtonian orbits in trace formulas for the oscillating part of the density of states. The signatures of non-Newtonian orbits in the density of states have recently been identified experimentally.