In 1977, the amateur mathematician Robert Ammann found several sets of aperiodic tiles. This example, named set A5, is certainly the most celebrated Ammann tiling. It is constructed by using only two simple building blocks: a square and a rhombus, which allows tilings with perfect 8-fold symmetry. The deflation factor is
, sometimes known as the "silver mean", and was the first irrational inflation factor known not related to the golden mean. The discovery of materials with quasicrystal structures changed the status of the theory of aperiodic tilings from mere recreational math to serious research.
