Criticality

First published: 2021

Brief summary

Stanford entry on phase transitions and criticality.

Article

Criticality concerns the behaviour of systems near a continuous phase transition. At a critical point, the distinction between competing phases changes and fluctuations can occur across a wide range of spatial and temporal scales.

Near criticality, correlation lengths grow and local changes can be associated with behaviour over much larger distances. Observable quantities often follow power laws characterised by critical exponents rather than a single typical scale.

Different physical systems can display the same critical exponents and scaling relations. This universality allows systems with different microscopic components to be grouped according to a smaller set of large-scale properties such as dimensionality and symmetry.

Renormalisation methods explain how descriptions change when a system is viewed at successively larger scales. Critical phenomena are established in statistical physics, while applications of criticality concepts to biological or social systems require separate empirical evidence for each proposed case.

Source details and credits

• Source / publisher: Stanford Encyclopedia of Philosophy
• Source type: Reference article
• URL type: WWW
• Credits: Stanford Encyclopedia of Philosophy
• URL: https://plato.stanford.edu/entries/physics-criticality/