Transfixing tetrahedrons

As a whirling dervish spins, his long skirt can form mesmerizing shapes such as a three-faced pyramid that rotates more slowly than its wearer. Dervishes are Sufi Muslims who represent the revolving heavens with their spinning dance, and it turns out the dance also mirrors the physics of a spinning Earth.

The flowing shapes made by a dervish’s skirt, physicists have discovered, depend on the same force that deflects objects to the right in the Northern Hemisphere: the Coriolis effect. As the spinning skirt’s fabric flows into a pyramidal shape, it is deflected similarly to the Earth’s atmosphere flowing over the spinning planet, scientists report November 26 in the New Journal of Physics.

Only by including the Coriolis effect could the researchers’ equations reproduce the rotating peaks and valleys of real dervishes’ skirts.