Secrets of cornstarch fluid unveiled
Dump enough cornstarch into a swimming pool, and you can walk across the water’s surface. Scientists have now revealed the secret of this YouTube party trick.
When struck by a foot, the particles suspended in the water jam together like snow piling up in front of a snowplow. The compaction forms a hard patch that can push back with the same amount of bone-crushing pressure concentrated at the tip of a high heel, researchers report in the July 12 Nature.
“If you were to punch the suspension, you might break your wrist,” says Scott Waitukaitis, a physicist at the University of Chicago who was inspired to study the goop after watching videos of people running on top of it.
Water added to equal or larger quantities of cornstarch has long been a staple of science fair demos, thanks to the mixture’s Jekyll-and-Hyde personality. A non-Newtonian fluid, it doesn’t behave like regu