Meet the Gömböcs: Weebles for adults

Readers of a certain age will remember Weebles, the self-righting plastic toys famous for their catchphrase: “Weebles wobble but they don’t fall down!”

The geometric term for a Weeble-like object is a mono-monostatic body, which means that it has one stable resting position and only one unstable point of balance. Weebles are weighted so that their centre of mass is shifted from their geometric centre, hence they wobble but do not fall over.

The concept of a homogeneous (ie, not weighted) and convex mono-monostatic body was first proposed by Russian mathematician Vladimir Arnold in 1995. It is fairly straightforward to construct a concave mono-monostatic body, but the convex version is much more tricky and no one was sure if such an object existed until the problem was solved by a pair of Hungarians, engineer Gábor Domokos and architect Péter Várkonyi.

Domokos and Várkonyi created their first prototype in 2006 and named it the Gömböc, after a spherical Hungarian dumpling. The Gömböc is a sphere-like shape that comes in an infinite number of varieties, although most of the shapes cannot be manufactured because they are too close to a sphere. If placed on a horizontal surface in an arbitrary position the Gömböc returns to the stable equilibrium point, purely on account of its shape.

All Gömböcs have a strict shape tolerance of about 0.1mm per 10cm, and this sensitivity means that you are unlikely to find spontaneous forms of the Gömböc in nature, such as pebbles.

Evolution, however, came up with a use for the phenomenon in the shell of the Indian star tortoise (Geochelone elegans), whose highly domed carapace helps it to self-right if it falls on its back.

If you would like to wobble your own Gömböc on your desk or dispensing bench, there is only one place to go. Check out the “only official Gömböc shop in the world” at www.gomboc-shop.com

Prices start at €99 for a small aluminium model, rising to over €1,000 for numbered, limited edition versions in a range of materials.

The largest Gömböc in the world is due to be displayed in the Hungarian pavilion at this year’s Shanghai Expo (2010). This giant steel wobbler is 1.5m high, 3m wide and weighs around two tons.