Pebbles on Mars and the Gömböc - a public lecture by Professor Gábor Domokos Event as iCalendar

(Mathematics, Physics, Environment)

21 March 2017

5:15pm

Venue: Lecture Theatre PLT1

Location: Ground Floor, Building 303, 38 Princes Street

Cost: Free

In 2012 NASA's Curiosity sent home stunning images of rounded pebbles on Mars.

It seemed to be a plausible hypothesis that these pebbles have been rounded while they were carried by an ancient river. However, more evidence was called for. The mathematical theory that finally led to the required geophyiscal argument is based on a curious idea of one of 20th century's most prominent mathematicians, V.I. Arnold, who in 1995 conjectured that convex, homogeneous solids with just two static balance points may exist.

Ten years later, based on a constructive proof by P.L. Varkonyi and the speaker, the first such object (dubbed Gömböc) was built.

In everyday terms, such a body (or pebble) would behave like a weeble toy, and it would always right itself on a flat surface under gravity to one and the same rest position.

The Gömböc is quite sensitive and almost never found in Nature, so it appeared to be a mathematical curiosity.

It came as a surprise when it turned out that the Gömböc plays an important role in the theory explaining the evolution of shapes in non-living Nature, such as sand grains, pebbles or asteroids. Although at first sight the connection appeared to be far-fetched, laboratory and field data showed a convincing match with theory-based predictions, and this turned out to be the key to understanding the provenance of Martian pebbles.