In physics, critical phenomena is the collective name associated with the physics of critical points. Most of them stem from the divergence of the correlation length, but also the dynamics slows down. Critical phenomena include scaling relations among different quantities, power-law divergences of some quantities (such as the magnetic susceptibility in the ferromagnetic phase transition) described by critical exponents, universality, fractal behaviour, ergodicity breaking. Critical phenomena take place in second order phase transition, although not exclusively.
The critical behavior is usually different from the mean-field approximation which is valid away from the phase transition, since the latter neglects correlations, which become increasingly important as the system approaches the critical point where the correlation length diverges. Many properties of the critical behavior of a system can be derived in the framework of the renormalization group.
In order to explain the physical origin of these phenomena, we shall use the Ising model as a pedagogical example.
Read more about Critical Phenomena: The Critical Point of The 2D Ising Model, Divergences At The Critical Point, Critical Exponents and Universality, Critical Dynamics, Ergodicity Breaking, Mathematical Tools, Applications
Famous quotes containing the words critical and/or phenomena:
“To take pride in a library kills it. Then, its motive power shifts over to the critical if admiring visitor, and apologies are necessary and acceptable and the fat is in the fire.”
—Carolyn Wells (1862–1942)
“Hence anyone who seeks for the true cause of miracles, and strives to understand natural phenomena as an intelligent being, and not to gaze at them as a fool, is set down and denounced as a impious heretic by those, whom the masses adore as the interpreters of nature and the gods.”
—Baruch (Benedict)