Editing Condensed matter physics (section)

===Emergence===
{{Main|Emergence}}

Theoretical understanding of condensed matter physics is closely related to the notion of [[emergence]], wherein complex assemblies of particles behave in ways dramatically different from their individual constituents.<ref name=coleman>{{cite book|last=Coleman |first=Piers |title=Introduction to Many Body Physics |year=2016 |publisher=Cambridge University Press |isbn=978-0-521-86488-6|url=http://www.cambridge.org/us/academic/subjects/physics/condensed-matter-physics-nanoscience-and-mesoscopic-physics/introduction-many-body-physics}}</ref><ref name=":0" /> For example, a range of phenomena related to high temperature superconductivity are understood poorly, although the microscopic physics of individual electrons and lattices is well known.<ref name=nsf-emergence>{{cite web|title=Understanding Emergence|url=https://www.nsf.gov/news/overviews/physics/physics_q01.jsp|publisher=National Science Foundation|access-date=30 March 2012}}</ref> Similarly, models of condensed matter systems have been studied where [[collective excitation]]s behave like [[photon]]s and [[electron]]s, thereby describing [[electromagnetism]] as an emergent phenomenon.<ref name=levin-rmp>{{cite journal|last=Levin|first=Michael|author2=Wen, Xiao-Gang |title=Colloquium: Photons and electrons as emergent phenomena|journal=Reviews of Modern Physics|year=2005|volume=77|issue=3|doi=10.1103/RevModPhys.77.871|arxiv= cond-mat/0407140 |bibcode= 2005RvMP...77..871L |pages=871–879 |s2cid=117563047}}</ref> Emergent properties can also occur at the interface between materials: one example is the [[lanthanum aluminate-strontium titanate interface]], where two band-insulators are joined to create conductivity and [[superconductivity]].