Editing Multiverse (section)

== History of the concept ==
According to some, the idea of infinite worlds was first suggested by the pre-Socratic Greek philosopher [[Anaximander]] in the sixth century BCE.<ref>{{Citation |last=Tarán |first=Leonardo |title=The Text of Simplicius' Commentary on Aristotle's Physics |work=Simplicius. Sa vie, son oeuvre, sa survie |year=1987 |url=http://dx.doi.org/10.1515/9783110862041.246 |access-date=2022-09-21 |place=Berlin, Germany; Boston, Massachusetts |publisher=DE GRUYTER |doi=10.1515/9783110862041.246 |isbn=9783110862041}}</ref> However, there is debate as to whether he believed in multiple worlds, and if he did, whether those worlds were co-existent or successive.<ref>
{{Cite journal |last=Kočandrle |first=Radim |title=Infinite Worlds in the Thought of Anaximander |date=December 2019 |url=https://www.cambridge.org/core/product/identifier/S000983882000004X/type/journal_article |journal=The Classical Quarterly |language=en |volume=69 |issue=2 |pages=483–500 |doi=10.1017/S000983882000004X |s2cid=216169543 |issn=0009-8388}}
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{{cite book |last1=Gregory |first1=Andrew |title=Anaximander: A Re-assessment |date=25 February 2016 |publisher=Bloomsbury Publishing |isbn=978-1-4725-0625-2 |page=121 |url=https://books.google.com/books?id=7TE0CwAAQBAJ&pg=PA121}}
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{{cite book |last1=Curd |first1=Patricia |last2=Graham |first2=Daniel W. |title=The Oxford Handbook of Presocratic Philosophy |date=27 October 2008 |publisher=Oxford University Press |isbn=978-0-19-972244-0 |pages=239–241 |url=https://books.google.com/books?id=lDvRCwAAQBAJ&pg=PA239}}
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{{cite thesis |last=Hatleback |first=Eric Nelson |date=2014 |title=Chimera of the Cosmos |type=PhD |chapter= |publisher=University of Pittsburgh |url=https://d-scholarship.pitt.edu/22668/1/Chimera_of_the_Cosmos_2.pdf |place=Pittsburgh, Pennsylvania}}</ref>

The first to whom we can definitively attribute the concept of innumerable worlds are the Ancient Greek [[Atomists]], beginning with [[Leucippus]] and [[Democritus]] in the 5th century BCE, followed by [[Epicurus]] (341–270 BCE) and [[Lucretius]] (1st century BCE).<ref name="Siegfried2019">
{{cite book |last1=Siegfried |first1=Tom |title=The Number of the Heavens: A History of the Multiverse and the Quest to Understand the Cosmos |date=17 September 2019 |publisher=Harvard University Press |isbn=978-0-674-97588-0 |pages=51–61 |url=https://books.google.com/books?id=L36mDwAAQBAJ&pg=PA51 |quote="In some worlds there is no sun and moon, in others they are larger than in our world, and in others more numerous. The intervals between the worlds are unequal; in some parts there are more worlds, in others fewer; some are increasing, some at their height, some decreasing; in some parts they are arising, in others falling. They are destroyed by collision one with another. There are some worlds devoid of living creatures or plants or any moisture." ... Only an infinite number of atoms could have created the complexity of the known world by their random motions... In this sense, the atomist-multiverse theory of antiquity presents a striking parallel to the situation in science today. The Greek atomists' theory of the ultimate nature of matter on the smallest scales implied the existence of multiple universes on cosmic scales. Modern science's most popular attempt to describe the fundamental nature of matter—superstring theory—also turns out (much to the theorists' surprise) to imply a vast multiplicity of vacuum states, essentially the same thing as predicting the existence of a multiverse.}}
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{{cite book |last1=Dick |first1=Steven J. |title=Plurality of Words: The Extraterrestrial Life Debate from Democritus to Kant |date=29 June 1984 |publisher=Cambridge University Press |isbn=978-0-521-31985-0 |pages=6–10 |url=https://books.google.com/books?id=Uak5AAAAIAAJ&pg=PA6 |quote=Why should other worlds have become the subject of scientific discourse, when they were neither among the phenomena demanding explanation?... it derived from the cosmogonic assumption of ancient atomism: the belief that the constituent bodies of the cosmos are formed by the chance coalescence of moving atoms, the same type of indivisible particles of which matter on Earth was composed... Given the occurrence of these natural processes, and the obvious example of potential stability revealed in our own finite world, it was not unreasonable to suppose the existence of other stable conglomerations. The atomists further employed the principle that when causes were present, effects must occur.6 Atoms were the agents of causality and their number was infinite. The effect was innumerable worlds in formation, in collision, and in decay."}}
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{{cite book |last1=Rubenstein |first1=Mary-Jane |title=Worlds Without End: The Many Lives of the Multiverse |date=11 February 2014 |publisher=Columbia University Press |isbn=978-0-231-15662-2 |pages=40–69 |chapter-url=https://books.google.com/books?id=fV-sAgAAQBAJ&pg=PA40 |chapter=Ancient Openings of Multiplicity}}
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{{cite web |last1=Sedacca |first1=Matthew |title=The Multiverse Is an Ancient Idea |url=https://nautil.us/the-multiverse-is-an-ancient-idea-236401/ |website=Nautilus |access-date=4 December 2022 |date=30 January 2017 |quote=The earliest hints of the multiverse are found in two ancient Greek schools of thought, the Atomists and the Stoics. The Atomists, whose philosophy dates to the fifth century B.C., argued that that the order and beauty of our world was the accidental product of atoms colliding in an infinite void. The atomic collisions also give rise to an endless number of other, parallel worlds less perfect than our own.}}
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{{cite web |last1=Siegfried |first1=Tom |title=Long Live the Multiverse! |url=https://blogs.scientificamerican.com/observations/long-live-the-multiverse/ |website=Scientific American Blog Network |date=2019 |quote=Leucippus and Democritus believed that their atomic theory required an infinity of worlds... Their later follower, Epicurus of Samos, also professed the reality of multiple worlds. "There are infinite worlds both like and unlike this world of ours"...}}
</ref> In the third century BCE, the philosopher [[Chrysippus]] suggested that the world eternally expired and regenerated, effectively suggesting the existence of multiple universes across time.<ref name=Sedacca2017/> The concept of multiple universes became more defined in the [[Middle Ages]].{{Citation needed|date=August 2022}}

The American philosopher and psychologist [[William James]] used the term "multiverse" in 1895, but in a different context.<ref>James, William, ''The Will to Believe'', 1895; and earlier in 1895, as cited in [[OED]]'s new 2003 entry for "multiverse": {{citation|url=https://books.google.com/books?id=HA0MAAAAIAAJ&pg=PA10|date=October 1895|last=James|first=William|journal=Int. J. Ethics|volume=6|page=10|title=Is Life Worth Living?|quote=Visible nature is all plasticity and indifference, a multiverse, as one might call it, and not a universe.|doi=10.1086/205378|issue=1}}</ref>

The concept first appeared in the modern scientific context in the course of the debate between [[Ludwig Boltzmann|Boltzmann]] and [[Ernst Zermelo|Zermelo]] in 1895.<ref>{{cite book |last1=Ćirković |first1=Milan M. |editor1-last=Kragh |editor1-first=Helge |editor2-last=Longair |editor2-first=Malcolm |title=The Oxford Handbook of the History of Modern Cosmology |date=6 March 2019 |publisher=Oxford University Press |isbn=978-0-19-254997-6 |chapter-url=https://books.google.com/books?id=OsKKDwAAQBAJ&pg=PA467 |chapter=Stranger things: multiverse, string cosmology, physical eschatology}}</ref>

In [[Dublin]] in 1952, [[Erwin Schrödinger]] gave a lecture in which he jocularly warned his audience that what he was about to say might "seem lunatic". He said that when his equations seemed to describe several different histories, these were "not alternatives, but all really happen simultaneously".<ref>{{Cite web |date=2012-04-05 |title=Erwin Schrödinger and the Quantum Revolution by John Gribbin: review |url=https://www.telegraph.co.uk/culture/books/bookreviews/9188438/Erwin-Schrodinger-and-the-Quantum-Revolution-by-John-Gribbin-review.html |access-date=2023-09-24 |website=The Telegraph |language=en}}</ref> This sort of duality is called "[[Quantum superposition|superposition]]".