Editing Ekpyrotic universe (section)

== Origins ==

The original ekpyrotic model was introduced by Justin Khoury, [[Burt Ovrut]], [[Paul Steinhardt]] and [[Neil Turok]] in 2001.<ref>{{cite journal | last1 = Khoury | first1 = Justin | last2= Ovrut | first2= Burt A.| last3= Steinhardt | first3= Paul J. | last4= Turok |first4= Neil |title = The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang| journal = Physical Review D| volume = 64 | issue = 12 | pages = 123522 | doi = 10.1103/PhysRevD.64.123522| arxiv = hep-th/0103239 | year = 2001 | bibcode = 2001PhRvD..64l3522K | s2cid = 374628 }}</ref>

Steinhardt created the name based on the [[Ancient Greek]] word [[ekpyrosis]] (ἐκπύρωσις, "conflagration"), which refers to a [[Stoicism|Stoic]] cosmological model in which the universe is caught in an eternal cycle of fiery birth, cooling and rebirth.<ref>'The dissolution of the universe into fire'. In Stoic philosophy, ''ekpyrosis'', all-engulfing cosmic fire, represents the contractive phase of eternally-recurring destruction and re-creation. On "ekpyrosis" see generally [[Michael Lapidge]], "Stoic Cosmology", in John M. Rist, ''The Stoics,'' Cambridge University Press, 1978, pp. 161–186 [180–184].{{ISBN?}}</ref>

The theory addresses the fundamental question that remains unanswered by the [[Big Bang]] inflationary model, "What happened before the Big Bang?" The explanation, according to the ekpyrotic theory, is that the Big Bang was actually a big bounce, a transition from a previous epoch of contraction to the present epoch of expansion. The key events that shaped our universe occurred before the bounce, and, in a cyclic version, the universe bounces at regular intervals.<ref>{{cite journal | last1 = Steinhardt | first1 = P. J. | last2=Turok | first2=N.| title = A Cyclic Model of the Universe | journal = [[Science (journal)|Science]] | volume = 296 | issue = 5572 | pages = 1436–1439 | date = 2002-04-25 | doi = 10.1126/science.1070462 | bibcode = 2002Sci...296.1436S | arxiv = hep-th/0111030 | pmid=11976408| s2cid = 1346107 }}</ref>