As complex as a toy
Tadashi Tokieda drops a small cedar ball into an empty soup bowl and begins swirling the bowl on a tabletop with his hand. As the bowl moves in circles, so does the ball. Tokieda adds a second ball and a third, and they swirl, too. When he adds a fourth, the balls’ smooth movements become jerky. A fifth and sixth add to the confusion as the balls are influenced not just by the bowl’s movement, but also by their interactions with each other. A seventh ball triggers something odd. The confusion subsides, and the balls, now influenced largely by their interactions with each other, begin to swirl in the opposite direction of the bowl’s motion. Tokieda explains that the change is analogous to the shift of particles moving freely in a gas to those crowded in a liquid. “A transition takes place,” Tokieda tells the crowd watching his demonstration earlier this month at...