Linked from
The 23 pages that link to Order parameter, each with the reason it gives.
Lev LandauRelated: It is the central variable in Landau’s phenomenological account of phase changes.
Self-organizationRelated: It makes the onset and strength of collective order measurable.
Critical phenomenaRelated: Its vanishing or changing value often marks the continuous transition.
Finite-size scalingRelated: Its size-dependent distribution often tracks the onset of order.
Liquid crystalRelated: It quantifies how strongly molecules share a common orientation.
PhaseRelated: Its value can identify which phase a material occupies.
Classical spin modelsRelated: Magnetization often measures the ordering that spin models undergo.