Science & Technology

The Gömböc Is the World's Only Artificial Self-Righting Shape

You know those inflatable clown bop bags that always stand back up no matter how hard they're punched down? The gömböc is basically that. The difference is this shape was born of mathematical theory, it has a consistent weight throughout, and you'd be hard-pressed to find one at a kid's birthday part.

A statue of a gömböc by József Zalavári in Budapest, Hungary

Can't Hold This Down

The gömböc is the world's only artificial self-righting shape. What this means is that no matter how it is placed on a flat surface, it will always find its way back to the same position. It's like a weighted punch bag in that way. But unlike the punch bag, the gömböc has a consistent density and weight throughout. The way it rights itself is due strictly to its unique shape: It has a wide, curved bottom that's surrounded by almost-flat sides, and a curved ridge on top not unlike a stegosaurus.

It's what is called a mono-monostatic shape, meaning it has one stable and one unstable point. (Place the shape on any side and it will right itself to the stable point, usually slowly with a rocking or vibrating; place the shape at the unstable point and it will flop more quickly to the stable point.) Hungarian engineers Gábor Domokos and Péter Várkonyi, both of the Budapest University of Technology and Economics, invented this shape in 2006.

The shape of the Indian Star Tortoise resembles a gömböc. This tortoise rolls easily without relying much on its limbs.

A Turtle Hurdle

This thing is fascinating to look at and watch wiggle back to its stable point, but it's even cooler than its unique aesthetics. For one, according to Gizmodo, "the different angles and proportions have to be measured to within ten microns — one tenth of the thickness of a human hair — to make the shape work." The shape may also give us insight as to why and how turtles are able to get back on their feet when upside down without the use of their limbs. Yes, highly domed turtle shells are nature's own gömböcs. Seeing math and nature come together sure is a beautiful thing.

The Story Behind the Invention of the Gömböc

Written by Joanie Faletto March 22, 2017

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