This is a visualization of what happens when Pappus's theorem is iterated. Pappus's theorem is a basic theorem in projective geometry, going back to Pappus of Alexandria, an ancient Greek mathematician. The image illustrates the research in the paper Pappus's Theorem and the Modular Group, I.H.E.S. Publications Mathematiques , Vol. 78 pp. 187-206, by Richard Evan Schwartz. Credit: Rich Schwartz. Courtesy: National Science Foundation.
Why does a returning boomerang come back?
When most of us think of boomerangs, we imagine somebody throwing a curved stick that eventually turns around and comes right back to the thrower's hand. This device is simply amazing, and a wonderful application of some laws of physics relating to aerodynamic lift and angular momentum.