Symmetry in crystallography

The science of crystals involves symmetry. Symmetry is also an excellent li nk to other fields of human endeavor. The first scientific crystallographer , Johannes Kepler, came to the idea of close packing when he was considerin g the symmetry of snow crystals. When Louis Pasteur observed crystal and mo lecular chirality, he opened a Pandora's box of the notion of the dissymmet ry of the universe. Since the start of X-ray crystallography in 1912, empha sis has been on single-crystal symmetry, and the held has moved from triump h to triumph. In the late 1920s, however, interest in less than perfect str uctures developed, leading to the establishment of molecular biology. Helic al symmetries were found to characterize life's most important molecules. S ymmetry considerations were decisive in these: discoveries, which stimulate d the expansion of the symmetry concept. In the mid-1980s, the belief that fivefold symmetry was a noncrystallographic symmetry crumbled, and the conc ept of the crystal had to be revised. Crystallography has now become the sc ience of structures. Symmetry has helped crystallography to influence the a rts. This tends to unify our culture - a side effect of the enormous work o f uncovering the secrets of matter for the betterment of human life.