Editing Holographic principle (section)

==The AdS/CFT correspondence==

{{Main|AdS/CFT correspondence}}
[[File:AdS CFT.png|thumb|upright=0.5|Conjectured relationship of adS/CFT]]
The '''anti-de Sitter/conformal field theory correspondence''', sometimes called '''Maldacena duality''' (after ref.<ref name=":0">{{Cite journal |last=Maldacena |first=Juan |date=March 1998 |title=The large $N$ limit of superconformal field theories and supergravity |url=https://www.intlpress.com/site/pub/pages/journals/items/atmp/content/vols/0002/0002/a001/ |journal=Advances in Theoretical and Mathematical Physics |language=EN |volume=2 |issue=2 |pages=231–252 |doi=10.4310/ATMP.1998.v2.n2.a1 |bibcode=1998AdTMP...2..231M |issn=1095-0753|doi-access=free |arxiv=hep-th/9711200 }}</ref>) or '''gauge/gravity duality''', is a conjectured relationship between two kinds of physical theories. On one side are [[anti-de Sitter space]]s (AdS) which are used in theories of [[quantum gravity]], formulated in terms of [[string theory]] or [[M-theory]]. On the other side of the correspondence are [[conformal field theory|conformal field theories]] (CFT) which are [[quantum field theory|quantum field theories]], including theories similar to the [[Yang–Mills theory|Yang–Mills theories]] that describe elementary particles.

The duality represents a major advance in understanding of string theory and quantum gravity.<ref name="de Haro et al. 2013, p.2">de Haro et al. 2013, p. 2.</ref> This is because it provides a [[non-perturbative]] formulation of string theory with certain [[boundary condition]]s and because it is the most successful realization of the holographic principle.

It also provides a powerful toolkit for studying [[coupling (physics)|strongly coupled]] quantum field theories.<ref>Klebanov and Maldacena. 2009.</ref> Much of the usefulness of the duality results from a strong-weak duality: when the fields of the quantum field theory are strongly interacting, the ones in the gravitational theory are weakly interacting and thus more mathematically tractable. This fact has been used to study many aspects of [[nuclear physics|nuclear]] and [[condensed matter physics]] by translating problems in those subjects into more mathematically tractable problems in string theory.

The AdS/CFT correspondence was first proposed by [[Juan Maldacena]] in late 1997.<ref name=":0" /> Important aspects of the correspondence were elaborated in articles by [[Steven Gubser]], [[Igor Klebanov]], and [[Alexander Markovich Polyakov]], and by [[Edward Witten]]. By 2015, Maldacena's article had over 10,000 citations, becoming the most highly cited article in the field of [[high energy physics]].<ref name="inspire">{{cite web |url= https://inspirehep.net/info/hep/stats/topcites/2014/alltime.html |title=Top Cited Articles of All Time (2014 edition) | publisher= [[INSPIRE-HEP]] |author=<!--Staff writer(s); no by-line.--> | access-date=26 December 2015}}</ref>