Corn Starch Holes

As I drive from Cambridge to Madison this weekend, with all my Earthly possessions in the back of the car, here’s some high octane entertainment for you.



Corn starch mixed with water is a dilatant fluid. That is, when you apply a shear force its viscosity dramatically increases and it behaves more like a solid; once the shearing stops, the fluid starts flowing again. The shear force could come from the vibrations of an earthquake or loudspeaker, or simply shoving your finger into a bowl of the stuff quickly (fun for the whole family!). Ketchup and some clay soils are also dilatant. In the video, the continual application of the shearing by the vibrations keeps the mixture in a perpetual state of high viscosity, so when the holes are created they don’t collapse. Fascinatin’.

Credit to Booker T. and the M.G.’s, and the Center for Nonlinear Dynamics, UT Austin.

Update 9/15/06: Thanks to constructive input of an anonymous reviewer who pointed out a careless mistake, and a hole in my knowledge. More later.