Doing the ‘impossible’: researchers roll a ball down a wall

Monday, June 2, 2025

Waterloo Engineering researchers have done something that was previously believed to be impossible – roll a sphere down a totally vertical surface.

The slow rolling motion was unexpectedly recorded by high-speed cameras after months of trial, error and theoretical calculations by two collaborating research teams.

“When we first saw it happening, we were frankly in disbelief,” said Dr. Sushanta Mitra, a professor of mechanical and mechatronics engineering, and executive director of the Waterloo Institute for Nanotechnology.

“We double-checked everything because it seemed to defy common sense. There was excitement in the lab when we confirmed it wasn’t a fluke and that this was real vertical rolling.”

Go to Redefining physics to roll a ball vertically for the full story.