Abstract

The magnetosphere is quite clearly “complex” as the word is used in everyday speech. However, in the last 15 to 20 years there has been a growing thread in magnetospheric physics which draws from, and develops, the emerging set of concepts and techniques which are now maturing to form a science of complex systems. Here “complexity” has a more specific meaning, usually implying system properties which cannot simply be deduced from the properties of the component parts. A particularly well-studied set of system properties has been derived from those used in the study of critical phenomena in condensed matter physics, notably correlation functions, power spectra and burst distributions. I will talk about these 3 measurements, why they have been made, how they have been adapted to the magnetospheric context, what they have told us so far and what I think the current issues are in their interpretation. I will also sketch some future directions. My own work has been done with many colleagues but I would particularly like to acknowledge Mervyn Freeman (BAS) and Sandra Chapman (Warwick) for collaboration over many years.