Scientists finally cracked the physics of the 'oloid'—this weird shape that touches every single part of its surface as it rolls along.
arXiv · March 17, 2026 · 2603.15145
The Takeaway
The oloid is a strange, curvy skeleton made from two interlocking circles that rolls in a wobbling path. While it has been a popular mathematical toy for nearly a century, researchers only just produced the exact analytical formula for how its mass is distributed, solving the mystery of its unique rolling resistance.
From the abstract
The oloid is defined as the convex hull of two unit circles in perpendicular planes, each passing through the center of the other. In this paper we derive an analytical expression for the moment of inertia tensor of an oloid with uniform density and confirm the result numerically.