Statistics and the shell model for chaotic motion in atomic nuclei

The paper concerns the statistical properties of nuclei and their interpretation in terms of chaotic motion. The discussion centres on the very different features of averages and fluctuations in nuclei, and in other many-body systems. Arguments are put forward to show that averages are determined by the dynamics, and therefore carry dynamical information, while fluctuations reflect chaotic behaviour, are generic for finite quantum systems, and carry no information content. (UK)