Universe

=== Philosophical models ===
{{Further|Cosmology}}
{{See also|Pre-Socratic philosophy|Physics (Aristotle)|Hindu cosmology|Islamic cosmology|Philosophy of space and time}}
The [[pre-Socratic philosophy|pre-Socratic Greek philosophers]] and Indian philosophers developed some of the earliest philosophical concepts of the universe.<ref name=Routledge /><ref>{{cite book|title=The Unfinished Universe|page=21|publisher=Oxford University Press|first=Louise B.|last=Young |year=1993 |isbn=978-0-195-08039-1 |oclc=26399171}}</ref> The earliest Greek philosophers noted that appearances can be deceiving, and sought to understand the underlying reality behind the appearances. In particular, they noted the ability of matter to change forms (e.g., ice to water to steam) and several philosophers proposed that all the physical materials in the world are different forms of a single primordial material, or ''[[arche]]''. The first to do so was [[Thales]], who proposed this material to be [[Water (classical element)|water]]. Thales' student, [[Anaximander]], proposed that everything came from the limitless ''[[Apeiron (cosmology)|apeiron]]''. [[Anaximenes of Miletus|Anaximenes]] proposed the primordial material to be [[Air (classical element)|air]] on account of its perceived attractive and repulsive qualities that cause the ''arche'' to condense or dissociate into different forms. [[Anaxagoras]] proposed the principle of ''[[Nous]]'' (Mind), while [[Heraclitus]] proposed [[fire (classical element)|fire]] (and spoke of ''[[logos]]''). [[Empedocles]] proposed the elements to be earth, water, air and fire. His four-element model became very popular. Like [[Pythagoras]], [[Plato]] believed that all things were composed of [[number]], with Empedocles' elements taking the form of the [[Platonic solids]]. [[Democritus]], and later philosophers—most notably [[Leucippus]]—proposed that the universe is composed of indivisible [[atom]]s moving through a [[void (astronomy)|void]] ([[vacuum]]), although [[Aristotle]] did not believe that to be feasible because air, like water, offers [[Drag (physics)|resistance to motion]]. Air will immediately rush in to fill a void, and moreover, without resistance, it would do so indefinitely fast.<ref name=Routledge />

Although Heraclitus argued for eternal change,<ref>{{cite SEP|url-id=heraclitus |title=Heraclitus |date=September 3, 2019 |last=Graham |first=Daniel W.}}</ref> his contemporary [[Parmenides]] emphasized changelessness. Parmenides' poem ''On Nature'' has been read as saying that all change is an illusion, that the true underlying reality is eternally unchanging and of a single nature, or at least that the essential feature of each thing that exists must exist eternally, without origin, change, or end.<ref>{{cite SEP|url-id=parmenides |title=Parmenides |date=October 19, 2020 |first=John |last=Palmer}}</ref> His student [[Zeno of Elea]] challenged everyday ideas about motion with several famous [[Zeno's paradoxes|paradoxes]]. Aristotle responded to these paradoxes by developing the notion of a potential countable infinity, as well as the infinitely divisible continuum.<ref>{{cite SEP|url-id=zeno-elea |title=Zeno of Elea |date=April 8, 2021 |first=John |last=Palmer}}</ref><ref>{{cite IEP|url-id=zenos-paradoxes |title=Zeno's Paradoxes |first=Bradley |last=Dowden}}</ref> Unlike the eternal and unchanging cycles of time, he believed that the world is bounded by the celestial spheres and that cumulative stellar magnitude is only finitely multiplicative.

The [[Indian philosophy|Indian philosopher]] [[Kanada (philosopher)|Kanada]], founder of the [[Vaisheshika]] school, developed a notion of [[atomism]] and proposed that [[light]] and [[heat]] were varieties of the same substance.<ref>[[Will Durant]], ''Our Oriental Heritage'': {{blockquote|"Two systems of Hindu thought propound physical theories suggestively similar to those of [[Ancient Greece|Greece]]. Kanada, founder of the Vaisheshika philosophy, held that the world is composed of atoms as many in kind as the various elements. The [[Jainism|Jains]] more nearly approximated to [[Democritus]] by teaching that all atoms were of the same kind, producing different effects by diverse modes of combinations. Kanada believed light and heat to be varieties of the same substance; [[Udayana]] taught that all heat comes from the Sun; and [[Vācaspati Miśra|Vachaspati]], like [[Isaac Newton|Newton]], interpreted light as composed of minute particles emitted by substances and striking the eye."}}</ref> In the 5th century AD, the [[Buddhist atomism|Buddhist atomist]] philosopher [[Dignāga]] proposed [[atom]]s to be point-sized, durationless, and made of energy. They denied the existence of substantial matter and proposed that movement consisted of momentary flashes of a stream of energy.<ref>Stcherbatsky, F. Th. (1930, 1962), ''Buddhist Logic'', Volume 1, p. 19, Dover, New York: {{blockquote|"The Buddhists denied the existence of substantial matter altogether. Movement consists for them of moments, it is a staccato movement, momentary flashes of a stream of energy... "Everything is evanescent",... says the Buddhist, because there is no stuff... Both systems <nowiki>[</nowiki>[[Samkhya|Sānkhya]], and later Indian Buddhism<nowiki>]</nowiki> share in common a tendency to push the analysis of existence up to its minutest, last elements which are imagined as absolute qualities, or things possessing only one unique quality. They are called "qualities" (''guna-dharma'') in both systems in the sense of absolute qualities, a kind of atomic, or intra-atomic, energies of which the empirical things are composed. Both systems, therefore, agree in denying the objective reality of the categories of Substance and Quality,... and of the relation of Inference uniting them. There is in Sānkhya philosophy no separate existence of qualities. What we call quality is but a particular manifestation of a subtle entity. To every new unit of quality corresponds a subtle quantum of matter which is called ''guna'', "quality", but represents a subtle substantive entity. The same applies to early Buddhism where all qualities are substantive... or, more precisely, dynamic entities, although they are also called ''dharmas'' ('qualities')."}}</ref>

The notion of [[temporal finitism]] was inspired by the doctrine of creation shared by the three [[Abrahamic religions]]: [[Judaism]], [[Christianity]] and [[Islam]]. The [[Christian philosophy|Christian philosopher]], [[John Philoponus]], presented the philosophical arguments against the ancient Greek notion of an infinite past and future. Philoponus' arguments against an infinite past were used by the [[Early Islamic philosophy|early Muslim philosopher]], [[Al-Kindi]] (Alkindus); the [[Jewish philosophy|Jewish philosopher]], [[Saadia Gaon]] (Saadia ben Joseph); and the [[Kalam|Muslim theologian]], [[Al-Ghazali]] (Algazel).<ref name="Viney1985">{{cite book |author=Viney |first=Donald Wayne |title=Charles Hartshorne and the Existence of God |publisher=SUNY Press |year=1985 |isbn=978-0-87395-907-0 |pages=65–68 |chapter=The Cosmological Argument}}</ref>

[[Pantheism]] is the [[Philosophy|philosophical]] [[Religion|religious]] belief that the universe itself is identical to [[divinity]] and a [[Deity|supreme being]] or entity.<ref name="Pearsall">{{cite book |last1=Pearsall |first1=Judy |title=The New Oxford Dictionary Of English |date=1998 |publisher=Clarendon Press |isbn=978-0-19-861263-6 |edition=1st |location=Oxford |page=1341}}</ref> The physical universe is thus understood as an all-encompassing, [[Immanence|immanent]] deity.<ref name="Edwards">{{cite book |last1=Edwards |first1=Paul |url=https://archive.org/details/encyclopediaofph08edwa |title=Encyclopedia of Philosophy |date=1967 |publisher=Macmillan |location=New York |page=[https://archive.org/details/encyclopediaofph08edwa/page/34 34] |url-access=registration}}</ref> The term 'pantheist' designates one who holds both that everything constitutes a unity and that this unity is divine, consisting of an all-encompassing, manifested [[God (male deity)|god]] or [[goddess]].<ref name="Edwards2">{{Cite book |title=Encyclopedia of Philosophy ed. Paul Edwards |publisher=Macmillan and Free Press |year=1967 |location=New York |page=34}}</ref><ref>{{cite book |last=Reid-Bowen |first=Paul |title=Goddess as Nature: Towards a Philosophical Thealogy |date=April 15, 2016 |publisher=[[Taylor & Francis]] |isbn=9781317126348 |page=70}}</ref> Pantheistic concepts date back thousands of years, and pantheistic elements have been identified in various religious traditions.