Re:The result looks like a simple sine wave to me. (Score 5, Informative)

It's not that the resulting wave acts in a novel manner, what is suprising is the column of matter that shoots up afterwards (the jet). Quick and Dirty Summary of the aricle: As you increase ambient pressure on a losely packed cluster of particles you would expect the pressure response from a force to be lessened, resulting in a smaller jet. Instead the high pressure in-between the particles seems to act as a turbocharger, creating a larger force - evidenced by the much higher jet.