Quasicrystals and Symmetries

Quasi crystals are a new form of matter that challenge traditional symmetry rules in solids. Unlike regular crystals, which have repeating atomic patterns, quasi crystals exhibit forbidden symmetries and repeat at irrational frequencies. This unique structure is analogous to disharmonic sound, which appears noisy but is actually ordered. The video explains the differences between random, crystal, and quasi crystal arrangements, highlighting the complexity and unpredictability of quasi crystal patterns.

What is one of the two known types of atomic arrangements before the discovery of quasicrystals?

• Random arrangement

• Elevenfold symmetry

• Irrational frequency

• Pentagonal symmetry

How do quasicrystals differ from traditional crystals in terms of symmetry?

• They have no symmetry at all

• They follow the same symmetry rules as crystals

• They exhibit forbidden symmetries not found in traditional crystals

• They have only one type of symmetry

What is a unique feature of quasicrystals in terms of frequency?

• They repeat at two or more frequencies with a rational ratio

• They do not repeat at any frequency

• They repeat at a single frequency

• They repeat at two or more frequencies with an irrational ratio

What analogy is used to describe the ordered yet seemingly random nature of quasicrystals?

• A child's toy

• A building block

• A frozen network

• A disharmonic sound

Why might humans initially perceive quasicrystals as random?

• Their patterns are unpredictable without training

• They lack any form of order

• They are visually identical to traditional crystals

• They have a broad spectrum of frequencies