Editing Critical phenomena (section)

==Critical point in renormalization group theory==
The critical point is described by a [[conformal field theory]]. According to the [[renormalization group]] theory, the defining property of criticality is that the characteristic [[length scale]] of the structure of the physical system, also known as the [[correlation length]] ''ξ'', becomes infinite. This can happen along ''critical lines'' in [[phase space]]. This effect is the cause of the [[critical opalescence]] that can be observed as a binary fluid mixture approaches its liquid–liquid critical point.

In systems in equilibrium, the critical point is reached only by precisely tuning a control parameter.  However, in some [[non-equilibrium thermodynamics|non-equilibrium]] systems, the critical point is an [[attractor]] of the dynamics in a manner that is robust with respect to system parameters, a phenomenon referred to as [[self-organized criticality]].<ref>{{cite book | first1 = Kim | last1 = Christensen | first2 = Nicholas R. | last2 = Moloney | title = Complexity and Criticality | pages = Chapter 3 | publisher = [[Imperial College Press]] | year = 2005 | isbn = 1-86094-504-X }}</ref>