Why certain symmetries are mathematically forbidden in crystals

Roger Penrose: Forbidden crystal symmetry - Event Q&A · 23:53 · Video: The Royal Institution · Watch at the source

In short: In this Q&A, Sir Roger Penrose explores the fascinating world of non-repeating patterns and the mathematical rules that govern what can and cannot exist in crystal structures.

While classical crystallography dictates that only 2, 3, 4, and 6-fold symmetries are possible, Penrose discusses the existence of 'forbidden' symmetries. Since the 1970s, patterns exhibiting 5, 8, 10, and 12-fold 'almost' symmetric properties have been observed, deviating from exact symmetry by only an infinitesimal amount.

The discussion covers the practical application of these patterns in architecture, such as a granite and stainless steel tiling composed of thousands of diamond-shaped tiles. These tiles use specific matching rules to create a non-repeating pattern with 5-fold and 10-fold symmetry. This phenomenon is also present in the atomic structures of quasi-crystalline materials, a discovery that led to Dan Shectman receiving the 2011 Nobel Prize in Chemistry.

Opens the Intellect+ feed with this card first. Swipe up for the next one.

Sources

To cite this card, link to https://intellectplus.co.uk/app/ideas-roger-penrose-forbidden-crystal-symmetry-event-q-a.

How we source, check and correct cards: Editorial standards.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

Finding something worth knowing…