Our main aim is to examine whether the atoms and molecules constituting the world around us are distributed in space in a random and disordered fashion, like pebbles on the beach, or in an ordered pattern like the cells of a honeycomb. However, it is often impossible to make such a clear-cut distinction, and it is better not to use "order" and "disorder" as absolute terms but to speak instead of a "degree of order" and a "degree of disorder. " These concepts are fairly new in science. Up to about 20-30 years ago it was still believed (and in fact this belief can still be en­ countered today) that certain states of matter - such as gases, liquids, and amorphous solids - were characterized by a totally disordered distribution of the constituent particles, whilst crys­ tals, by contrast, exhibited perfectly ordered lattices. According to the present view, on the other hand, order and disorder often coexist inseparably from each other, though there are admittedly many cases in which "order" or "disorder" does describe quite accurately tbe actual state of affairs. Symptoms of disorder have recently been found in seemingly perfectly regular molecular structures, and symptoms of order in seemingly perfectly chaotic aggregations of particles. These dis­ coveries led to the formulation of new and important laws cor­ relating the structure of substances with their properties, and to tIlt' explanation of many phenomena in terms of changes in the degree of order.

Inhalt

1-Disorder.- 1. What constitutes a disordered arrangement?.- 2. The gaseous state of matter.- 3. Thermal motion in gases.- 2-Order.- 1. The symmetry of wallpaper patterns.- 2. Crystals.- 3. Invisible lattices.- 4. Crystals and the close packing of spheres.- 5. Crystals that are not close-packed assemblies of spheres.- 6. Same atoms but different crystals.- 7. Long-range order.- 8. Order in microcrystalline bodies.- 3-Elements of Order in Disorder.- 1. Short-range order and the structure of liquids.- 2. The amorphous solid state.- 3. Liquid crystals.- 4. Thermal motion of particles in liquids.- 4-Elements of Disorder in Order.- 1. Thermal motion of atoms and molecules in crystals.- 2. The gas-crystalline state of matter.- 3. Block structure.- 4. Dislocations.- 5. The dislocations move.- 6. Ideal crystals.- 7. Defects within the blocks.- 8. Crystals with errors.- 9. Order and disorder in binary alloys.- 10. Magnetic order.- 5-Order and Disorder in the World of Large Molecules.- 1. Long and branched molecules.- 2. Bundles of long molecules.- 3. Behavior of bundle polymers.- 4. Alignment of polymer molecules to form single crystals.- 5. The structure of polymers.- 6. The living cell.- 6-Transitions Between Order and Disorder.- 1. Iron vapor and solid air.- 2. Water-an exception to the rule.- 3. The growth of crystals.- 4. Spiral growth.- 5. Conversions between crystal structures.- 6. Delayed transitions.- 7. Particles do change place in crystals.- 7-Order or Disorder?.- 1. Probability and disorder.- 2. The tendency toward disorder.- 3. The tendency toward order.- 4. The struggle between order and disorder.