Number theory and neuroscience are probably not the first things that come to mind when you contemplate the circus. Yet along with the clowns and the fire-eaters, there’s a place for science under the big top. Performers and their coaches have to know, either instinctively or consciously, what the laws of physics and biology will permit them to do; moreover, a surprisingly large number of scientists are themselves circus fanatics, and a few are even performers. Perhaps it’s because the circus proves that science doesn’t stop at the lab door.
The crowds are always awed when the acrobats with Montreal’s Cirque du Soleil start twisting their bodies as they flip. But actually such twisting is, in a purely physical sense, easy. Any object resists efforts to turn it--this is the quality physicists call rotational inertia. Rotational inertia increases as the mass of an object is spread farther from its center ...
