Society of Physics Students, Department of Physics, Queens Campus

In 1968 Zabusky and Kruskal examined the continuum limit of the problem numerically, in which the number of atoms is increased and the spacing between the atoms is reduced so that it looks like a continuous string. They found that this system was described by a partial differential equation first put forward by two dutchmen Korteweg and de Vries (KdV) to describe unusual waves in shallow canals. These unusual water waves were first observed by Scott Russell while inspecting a canal near Edinburgh.

These solitary waves had a localized profile (like a Tsunami), but unlike most other water waves never broke or changed form. Zabusky and Kruskal found that when these special waves collided they passed through each other. Zabusky and Kruskal penned the name soliton to describe these particle-like wave excitations.

Zabusky and Kruskal's result spurred intensive studies by mathematical physicists who showed that the continuum system was governed by an infinite number of conservation laws. It was also found that the KdV equation supported very unusual oscillations that were localized. Recently it has been proposed that excitations like these have been found in experiments that look at the lattice dynamics of a three-dimensional structure: rocksalt.

All interested students and faculty are invited. Refreshments will be served.