Any system in nature has some set of properties. State variables refer to such properties and inform about the system’s state of interest for the observer. They can be: positions, orientations or rates of change of some property (e.g. anxiety state of a person, body position or orientation or their changes, respectively); relational variables that show the mutual relationship between two or more components, for example, interpersonal, inter-atomic /inter-molecular, or inter-galactic distances; collective properties of a large number of components (e.g., the average magnetization, density or concentration of particles or animals or the collective direction of motion of players, flocks of birds, schools of fish or fluid molecules.Collective state variables have different names in different areas of science. In chemistry they may be called reaction coordinates. In physics, psychology, kinesiology and neuroscience – order parameters. State variables as system’s descriptors are usually analyzed for stability in following ways: 1. How they behave when subject to perturbations and 2. How they behave under the change of the context . Their properties of stability are informative about system’s possible qualitative changes (i.e. phase transitions). Their long term states are called attractors (states attract the behavior of the system toward them and maintain it) and the unstable ones repellers (states repel the system from them).
Robert Hristovski 14.11.2016