Gravitational dispersion in a torsional wave machine
  We demonstrate that mechanical waves traveling in a torsional, mechanical wave machine exhibit dispersion due to gravity and the discreteness of the medium. We also show that although the dispersion due to discreteness is negligible, the dispersion due to gravity can be easily measured, and can be shown to disappear in a zero-gravity environment. 
Rafael de la Madrid, Alejandro Gonzalez, George Irwin
physics.class-ph gr-qc