Brain, Rain and Forest Fires -- What is critical about criticality: In praise of the correlation function

Henrik Jeldtoft Jensen

Published 2021-06-17Version 1

We present a brief review of power laws and correlation functions as measures of criticality and the relation between them. By comparing phenomenology from rain, brain and the forest fire model we discuss the relevant features of self-organisation to the vicinity about a critical state. We conclude that organisation to a region of extended correlations and approximate power laws may be behaviour of interest shared between the three considered systems.