Eric F. Brown over at "The Rheol World" has a new post of the guys from "The Big Bang Theory" having fun with Oobleck (cornstarch and water) on a music speaker. Sheldon Cooper does an adequate job of describing the phenomenon - it's not a complete description, but he certainly is not incorrect in anything he says.
Compare this with this awful video, only 6 seconds long and (about that many words too) which makes a total mess of the matter:
Oobleck is not thixotropic; it certainly shows signs of rheopexy, dilatancy and other non-Newtonian behavior, but not thixotropy.
This is another example of something I've discussed before: while the word "thixotropic" sounds like "thick", that association is completely inaccurate when it comes to understanding the meaning of the word. A thixotropic material will reversibly reduce its viscosity at a constant shear rate. When the shearing stops, the viscosity increases. The imaginary word "thinnotropic" would be closer to its true meaning.
Everything flows, but only the macromolecules are worth the time.
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