View source for Religion:Cosmology in medieval Islam

{{Short description|Description of the universe in Islam}}
'''Islamic cosmology''' is the [[Astronomy:Cosmology|cosmology]] of [[Religion:Muslim world|Islamic societies]].<ref>{{Cite web|title=Islamic Cosmology and Science|url=https://www.researchgate.net/publication/336044953|access-date=2021-09-13|website=ResearchGate|language=en}}</ref> It is mainly derived from the Qur'an, [[Religion:Hadith|Hadith]], [[Religion:Sunnah|Sunnah]], and current [[Religion:Islam|Islam]]ic as well as other pre-Islamic sources. The [[Religion:Quran|Qur'an]] itself mentions seven heavens.<ref name=":0">Qur'an 2:29</ref><ref>{{Cite web|title=Seven Heavens In Quran.|url=http://seven_heavens.html/|access-date=2021-09-13|website=seven_heavens.html}}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{Cite web|title=Seven Heavens – The Quranic Multiverse 41:12 – Islamic Web Library|url=http://www.islamicweblibrary.com/2019/03/19/seven-heavens-quran-4112/|access-date=2021-09-13|language=en-US}}</ref>

==Metaphysical principles==

===[[Duality (mathematics)|Duality]]===
In Islamic thought the cosmos includes both the '''Unseen Universe''' ({{lang-ar|عالم الغيب}}, ''{{transliteration|ar|ALA|Alam-al-Ghaib}}'') and the '''Observable Universe''' ({{lang-ar| عالم الشهود}}, ''Alam-al-Shahood'').<ref>{{Cite journal|last=Almirzanah|first=Syafaatun|date=2020-10-20|title=God, humanity and nature: Cosmology in Islamic spirituality|url=https://hts.org.za/index.php/hts/article/view/6130|journal=HTS Teologiese Studies / Theological Studies|language=en|volume=76|issue=1|pages=10|doi=10.4102/hts.v76i1.6130|s2cid=225146959|issn=2072-8050|hdl=2263/79559|hdl-access=free}}</ref> Nevertheless, both belong to the created universe. Islamic dualism does not constitute between spirit and matter, but between Creator ([[Religion:God in Islam|God]]) and creation.<ref>John Valk, Halis Albayrak, Mualla Selçuk ''An Islamic Worldview from Turkey: Religion in a Modern, Secular and Democratic State'' Springer, 31.10.2017 {{ISBN|9783319667515}} p. 148</ref> The latter including both the seen and unseen.

==Sufi cosmology==
{{Main|Religion:Sufi cosmology}}

Sufi cosmology ({{lang-ar|الكوزمولوجية الصوفية}}) is a general term for [[Astronomy:Cosmology|cosmological]] doctrines associated with the mysticism of [[Religion:Sufism|Sufism]]. These may differ from place to place, order to order and time to time, but overall show the influence of several different [[Astronomy:Cosmography|cosmographies]]:<ref>{{Cite web|title=Drunkenness and cosmology in Sufi poetry|url=https://www.wm.edu/news/stories/2018/drunkenness-and-cosmology-in-sufi-poetry.php|access-date=2021-09-13|website=William & Mary|language=en}}</ref><ref>{{Cite web|title=Sufi cosmology|url=https://www.onelittleangel.com/wisdom/quotes/sufism.asp?level=1}}</ref>

*The [[Religion:Quran|Quran]]'s testament concerning God and immaterial beings, the soul and the afterlife,<ref>{{Cite web|title=6: Renaissance and Early Modern Philosophy|url=https://www.utm.edu/staff/jfieser/class/110/6-renaissance.htm|access-date=2021-09-14|website=www.utm.edu}}</ref> the beginning and end of things, the seven heavens, etc.<ref>{{Cite web|last=Sûfî|first=Es|title=Sufi cosmology|url=https://sufier.wordpress.com/category/sufi-cosmology/|access-date=2021-09-14|website=Sufismen och Sufier|language=sv-SE}}</ref>
*The Neoplatonic views cherished by [[Religion:Islamic philosophy|Islamic philosophers]] like [[Biography:Avicenna|Avicenna]] and [[Biography:Ibn Arabi|Ibn Arabi]].<ref>{{Cite web|title=Neoplatonism in Islamic philosophy|url=http://www.muslimphilosophy.com/ip/rep/H003.htm|access-date=2021-09-14|website=www.muslimphilosophy.com}}</ref><ref>{{Cite web|title=Neoplatonism in Islamic philosophy - Routledge Encyclopedia of Philosophy|url=https://www.rep.routledge.com/articles/thematic/neoplatonism-in-islamic-philosophy/v-1|access-date=2021-09-14|website=www.rep.routledge.com|language=en}}</ref><ref>{{Cite journal|last=Bornstein|first=Pablo|date=October 2019|title=An Orientalist Contribution to "Catholic Science": The Historiography of Andalusi Mysticism and Philosophy in Julián Ribera and Miguel Asín|journal=Religions|language=en|volume=10|issue=10|pages=568|doi=10.3390/rel10100568|doi-access=free}}</ref>
*The [[Philosophy:Hermeticism|Hermetic]]-Ptolemaic spherical geocentric world.
*The Ishraqi visionary universe as expounded by Suhrawardi Maqtul.<ref>{{Cite web|title=Suhrawardi and Ishraqi Philosophy|url=https://www.independentphilosophy.net/Suhrawardi_and_Ishraqi_Philosophy.html|access-date=2021-09-14|website=www.independentphilosophy.net}}</ref><ref>{{Cite web|title=Sufi cosmology|url=https://www.onelittleangel.com/wisdom/quotes/sufism.asp|access-date=2021-09-14|website=Onelittleangel.com|language=en}}</ref>

== Quranic interpretations ==
{{See also|Qur'an and science|Islam and science}}Contemporary and traditional interpretations have generally held in line with general biblical cosmology, with a flat Earth with skies stacked on top of each other, with some believing them to be domes and others flat circles.<ref>{{Cite journal |last=Janos |first=Damien |date=April 2012 |title=Qur'ānic cosmography in its historical perspective: some notes on the formation of a religious worldview |url=http://www.tandfonline.com/doi/abs/10.1080/0048721X.2012.642573 |journal=Religion |language=en |volume=42 |issue=2 |pages=215–231 |doi=10.1080/0048721X.2012.642573 |s2cid=144051327 |issn=0048-721X}}</ref><ref>{{Cite book |last=Decharneux |first=Julien |url=https://www.degruyter.com/document/doi/10.1515/9783110794083/html |title=Creation and Contemplation: The Cosmology of the Qur'ān and Its Late Antique Background |date=2023-05-23 |publisher=De Gruyter |isbn=978-3-11-079408-3 |doi=10.1515/9783110794083}}</ref> Traditionalists rejected most concepts of Ptolemy's theories of a round Earth, and the debate continued for many centuries after the advent of Islam.<ref>''[https://www.academia.edu/93485940/Against_Ptolemy_Cosmography_in_Early_Kal%C4%81m_2022_ Against Ptolemy? Cosmography in Early Kalām (2022)].'' Omar Anchassi. ''Journal of the American Oriental Society'', ''142''(4), 851–881. <nowiki>https://doi.org/10.7817/jaos.142.4.2022.ar033</nowiki></ref>

There are several verses in the Qur'an (610–632) which some medieval and modern writers have reinterpreted as foreshadowing modern [[Astronomy:Cosmology|cosmological]] theories.<ref name="Salem">{{citation|title=The Evolution of the Universe: A New Vision|url=http://www.akamaiuniversity.us/pdf/BenSalem_JAHC_051.pdf|year=2007|author=Kamel Ben Salem|journal=European Journal of Science and Theology|access-date=2010-03-19}}</ref><ref name=":0" /> An early example of this can be seen in the work of the Islamic theologian [[Biography:Fakhr al-Din al-Razi|Fakhr al-Din al-Razi]] (1149–1209), in dealing with his conception of physics and the physical world in his ''Matalib''.<ref>{{Cite web|title=Fakhr al-Din al-Razi|url=https://www.oxfordbibliographies.com/view/document/obo-9780195390155/obo-9780195390155-0214.xml|access-date=2021-09-14|website=obo|language=en}}</ref><ref>{{Cite journal|last=Setia|first=Adi|date=2008-06-22|title=Time, motion, distance, and change in the Kalam of Fakhr al-Din al-Razi: a preliminary survey with special reference to the Matalib Aliyyah|url=https://go.gale.com/ps/i.do?p=AONE&sw=w&issn=17037603&v=2.1&it=r&id=GALE%7CA182036008&sid=googleScholar&linkaccess=abs|journal=Islam & Science|language=English|volume=6|issue=1|pages=13–30}}</ref> He discusses Islamic cosmology, criticizes the idea of the [[Geocentric model|Earth's centrality]] within the universe, and explores "the notion of the existence of a [[Physics:Multiverse|multiverse]] in the context of his commentary" on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds." He raises the question of whether the term "worlds" in this verse refers to "multiple [[Philosophy:World|world]]s within this single [[Astronomy:Universe|universe]] or [[Astronomy:Cosmos|cosmos]], or to many other universes or a multiverse beyond this known universe." He rejects the Aristotelian view of a single world or universe in favour of the existence of multiple worlds and universes, a view that he believed to be supported by the Qur'an and by the [[Religion:Ash'ari|Ash'ari]] theory of [[Philosophy:Atomism|atomism]].<ref name="Setia">{{cite journal|title=Fakhr Al-Din Al-Razi on Physics and the Nature of the Physical World: A Preliminary Survey|date=Winter 2004|author=Adi Setia |journal=Islam & Science|volume=2 |url=http://findarticles.com/p/articles/mi_m0QYQ/is_2_2/ai_n9532826/|access-date=2010-03-02|archive-url= https://web.archive.org/web/20090702235721/http://findarticles.com/p/articles/mi_m0QYQ/is_2_2/ai_n9532826/ |archive-date=2009-07-02|url-status=dead}}</ref><ref>{{Cite web|title=al-Razi, Fakhr al-Din (1149-1209)|url=https://www.muslimphilosophy.com/ip/rep/H044.htm|access-date=2021-09-14|website=www.muslimphilosophy.com}}</ref>

==Cosmology in the medieval Islamic world==

[[Astronomy:Cosmology|Cosmology]] was studied extensively in the [[Religion:Muslim world|Muslim world]] during what is known as the Islamic Golden Age from the 7th to 15th centuries.<ref>{{Cite web|url=https://www.metmuseum.org/toah/hd/astr/hd_astr.htm|access-date=2021-09-14|website=www.metmuseum.org|title=Astronomy and Astrology in the Medieval Islamic World &#124; Essay &#124; the Metropolitan Museum of Art &#124; Heilbrunn Timeline of Art History }}</ref> There are exactly seven verses in the [[Religion:Quran|Quran]] that specify that there are [[Religion:Seven Heavens|seven heavens]], "He it is who created for you all that is in the earth; then he turned towards the heavens, and he perfected them as seven heavens; and he has perfect knowledge of all things."
One verse says that each heaven or sky has its own order, possibly meaning laws of nature. Another verse says after mentioning the seven heavens "and similar earths".<ref>{{Cite web|title=Ayah al-Baqarah (The Cow) 2:29|url=https://www.islamawakened.com/quran/2/29/default.htm|access-date=2021-09-14|website=www.islamawakened.com}}</ref><ref name=":0" />

In 850, al-Farghani wrote ''Kitab fi Jawani'' ("''A compendium of the science of stars''"). The book primarily gave a summary of Ptolemic [[Astronomy:Cosmography|cosmography]]. However, it also corrected [[Biography:Ptolemy|Ptolemy]]'s ''[[Astronomy:Almagest|Almagest]]'' based on findings of earlier Iranian astronomers. Al-Farghani gave revised values for the [[Astronomy:Axial tilt|obliquity]] of the [[Astronomy:Ecliptic|ecliptic]], the [[Physics:Precession|precession]]al movement of the apogees of the Sun and the Moon, and the circumference of the Earth. The books were widely circulated through the Muslim world, and even translated into [[Social:Latin|Latin]].<ref>{{Harv|Dallal|1999|p=164}}</ref><ref>{{Cite web|title=Muslim Astronomers|url=http://althaqalayn.com/MuslimAstronomers.aspx|access-date=2021-09-14|website=althaqalayn.com}}</ref>

===Cosmography===
Islamic historian Michael Cook states that the "basic structure" of the Islamic universe according to scholars interpretation of the verses of the Quran and Islamic [[Religion:Hadith|traditions]] was of seven heavens above seven earths.<ref name="Cook-1983-26">{{cite book |last1=Cook |first1=Michael |title=Muhammad |date=1983 |publisher=Oxford University Press |isbn=0192876058 |page=26}}</ref> 
*"Allah is He Who Created seven firmaments and of the earth a similar number. Through the midst of them (all) descends His command: that ye may know that Allah has power over all things, and that Allah comprehends all things In (His) Knowledge." {{cite quran|65|12|style=nosup|expand=no}}

The seven earths formed parallel layers with human beings inhabiting the top layer and Satan dwelling at the bottom. The seven heavens also formed parallel layers; the lowest level being the sky we see from earth and the highest being paradise ([[Religion:Jannah|Jannah]]).<ref name="Cook-1983-26"/>  Other traditions describes the [[Religion:Seven Heavens#Islam|seven heavens]] as each having a notable prophet in residence that Muhammad visits during [[Religion:Isra and Mi'raj|Miʿrāj]]: Moses (Musa) on the sixth heaven,<ref>{{cite book |pages=[https://archive.org/details/whataresevenwond00depi_0/page/219 219]–220 |title=What Are the Seven Wonders of the World? And 100 Other Great Cultural Lists: Fully Explained |author=Peter D'Epiro |author2=Mary Desmond Pinkowish |name-list-style=amp |publisher=Doubleday |year=1998 |isbn=0-385-49062-3 |url-access=registration |url=https://archive.org/details/whataresevenwond00depi_0 }}</ref> Abraham (Ibrahim) on the seventh heaven,<ref>{{cite book|title=Mixer and Server |volume=27 |page=51 |year=1918 |author=Hotel and Restaurant Employee's International Alliance |author2=Bartenders' International League of America |name-list-style=amp}}</ref> etc.

{{Main|Religion:ʿAjā'ib al-makhlūqāt wa gharā'ib al-mawjūdāt}}
''ʿAjā'ib al-makhlūqāt wa gharā'ib al-mawjūdāt'' ({{lang-ar|عجائب المخلوقات و غرائب الموجودات}}, meaning ''Marvels of creatures and Strange things existing'') is an important work of [[Astronomy:Cosmography|cosmography]] by Zakariya ibn Muhammad ibn Mahmud Abu Yahya al-Qazwini who was born in Qazwin year 600 ([[Engineering:Islamic calendar|AH]] (1203 AD).

===Temporal finitism===

In contrast to ancient Greek philosophers who believed that the [[Astronomy:Universe|universe]] had an infinite past with no beginning, [[Philosophy:Medieval philosophy|medieval philosophers]] and [[Religion:Theology|theologians]] developed the concept of the universe having a finite past with a beginning (see [[Temporal finitism]]).  The [[Philosophy:Christian philosophy|Christian philosopher]], [[Biography:John Philoponus|John Philoponus]], presented the first such argument against the ancient Greek notion of an infinite past. His arguments were adopted by many most notably; early Muslim philosopher, [[Biography:Al-Kindi|Al-Kindi]] (Alkindus);{{additional citation needed|date=October 2016}} the Jewish philosopher, [[Biography:Saadia Gaon|Saadia Gaon]] (Saadia ben Joseph); and the Muslim theologian, [[Biography:Al-Ghazali|Al-Ghazali]] (Algazel).{{additional citation needed|date=October 2016}} They used two logical arguments against an infinite past, the first being the "argument from the impossibility of the existence of an actual infinite", which states:<ref name=Craig>{{citation|title=Whitrow and Popper on the Impossibility of an Infinite Past|first=William Lane|last=Craig|journal=The British Journal for the Philosophy of Science|volume=30|issue=2|date=June 1979|pages=165–170 [165–6]|doi=10.1093/bjps/30.2.165}}</ref>

:"An actual infinite cannot exist."
:"An infinite temporal regress of events is an actual infinite."
:"∴ An infinite temporal regress of events cannot exist."

The second argument, the "argument from the impossibility of completing an actual infinite by successive addition", states:<ref name=Craig/>

:"An actual infinite cannot be completed by successive addition."
:"The temporal series of past events has been completed by successive addition."
:"∴ The temporal series of past events cannot be an actual infinite."

Both arguments were adopted by later Christian philosophers and theologians, and the second argument in particular became more famous after it was adopted by [[Biography:Immanuel Kant|Immanuel Kant]] in his thesis of the first antinomy concerning [[Time|time]].<ref name=Craig/>

====Amount of time====
The Quran states that the universe was created in six ayyam (days), in verse 50:38 among others.<ref>{{cite web|url=https://www.dar-alifta.org/Foreign/ViewFatwa.aspx?ID=8031|title=In how many days the heavens and the earth were created?|access-date=12 January 2020|work=Dar al-Ifta al-Misriyyah|archive-url=https://web.archive.org/web/20200112215308/https://www.dar-alifta.org/Foreign/ViewFatwa.aspx?ID=8031|archive-date=12 January 2020|url-status=live}}</ref> According to verse 70:4, one day in Quran is equal to 50,000 years on Earth. Therefore, Muslims interpret the description of a "six days" creation as six distinct periods or eons. The length of these periods is not precisely defined, nor are the specific developments that took place during each period.<ref>{{cite web|url=http://www2.nau.edu/~gaud/bio301/content/iscrst.htm|title=Islam creation story|work=nau.edu|access-date=12 January 2020|archive-url=https://web.archive.org/web/20191206043644/http://www2.nau.edu/~gaud/bio301/content/iscrst.htm|archive-date=6 December 2019|url-status=live}}</ref>

According to Michael Cook "early Muslim scholars" believed the amount of finite time creation had been assigned was about "six or seven thousand years" and that perhaps all but 500 years or so  had already passed. He quotes a tradition of Muhammad saying "in reference to the prospective duration" of the community of the Muslim [[Religion:Companions of the Prophet|companions]]: `Your appointed time compared with that of those who were before you is as from the afternoon prayer ([[Religion:Asr prayer|Asr prayer]]) to the setting of the sun'".<ref name="Cook-1983-31">{{cite book |last1=Cook |first1=Michael |title=Muhammad |date=1983 |publisher=Oxford University Press |isbn=0192876058 |pages=31}}</ref> Early Muslim Ibn Ishaq estimated the prophet Noah lived 1200 years after [[Biography:Adam|Adam]] was expelled from paradise, the prophet [[Biography:Abraham|Abraham]] 2342 years after Adam, [[Biography:Moses|Moses]] 2907 years, [[Biography:Jesus|Jesus]] 4832 years and [[Biography:Muhammad|Muhammad]] 5432 years.<ref name="Cook-1983-31"/>

The [[Religion:Fatimid Caliphate|Fatimid]] thinker [[Biography:Al-Mu'ayyad fi'l-Din al-Shirazi|al-Mu’ayyad fi’l-Din al-Shirazi]] (d. 1078) shares his own views about the creation of the world in 6 days. He rebukes the idea of the creation of the world in 6 cycles of either 24 hours, 1000 or 50,000 years, and instead questions both how creation can be measured in units of time when time was yet to be created, as well as how an infinitely powerful creator can be limited by the constraints of time, as it is itself part of his own creation. The [[Religion:Isma'ilism|Ismaili]] thinker [[Biography:Nasir Khusraw|Nasir Khusraw]] (d. after 1070) expands on his colleague's work. He writes that these days refer to cycles of creation demarcated by the arrival of God's messengers (''ṣāḥibān-i adwār''), culminating in the arrival of the [[Religion:Al-Qa'im Al Muhammad|Lord of the Resurrection]] (''Qāʾim al-Qiyāma''), when the world will come out of darkness and ignorance and “into the light of her Lord” (Quran 39:69). His era, unlike that of the enunciators of divine revelation (''nāṭiqs'') before him, is not one where God prescribes the people to work. Rather, his is an era of reward for those “who laboured in fulfilment of (the Prophets') command and with knowledge”.<ref>{{Cite journal|last=Virani|first=Shafique|title=The Days of Creation in the Thought of Nasir Khusraw|url=https://www.academia.edu/37219457|journal=Nasir Khusraw: Yesterday, Today, Tomorrow|date=January 2005 |language=en}}</ref>

===Galaxy observation===
The Arab astronomer Alhazen (965–1037) made the first attempt at observing and measuring the [[Astronomy:Milky Way|Milky Way]]'s [[Astronomy:Parallax|parallax]],<ref>{{Cite book
 | title=Great Muslim Mathematicians | first=Mohaini
 | last=Mohamed | year=2000 | publisher=Penerbit UTM
 | isbn=983-52-0157-9 | pages=49–50 | oclc=48759017 }}</ref> and he thus "determined that because the Milky Way had no parallax, it was very remote from the [[Astronomy:Earth|earth]] and did not belong to the atmosphere."<ref>{{cite web
 | title=Popularisation of Optical Phenomena: Establishing the First Ibn Al-Haytham Workshop on Photography
 |author1=Bouali, Hamid-Eddine |author2=Zghal, Mourad |author3=Lakhdar, Zohra Ben | publisher=The Education and Training in Optics and Photonics Conference
 | year=2005 | url=http://spie.org/etop/ETOP2005_080.pdf|access-date=2008-07-08 }}</ref>  The Persian astronomer Abū Rayhān al-Bīrūnī (973–1048) proposed the Milky Way [[Astronomy:Galaxy|galaxy]] to be "a collection of countless fragments of the nature of nebulous stars."<ref>{{MacTutor Biography | id=Al-Biruni | title=Abu Rayhan Muhammad ibn Ahmad al-Biruni }}</ref> The Andalusian astronomer Ibn Bajjah ("Avempace", d. 1138) proposed that the Milky Way was made up of many stars which almost touched one another and appeared to be a continuous image due to the effect of [[Physics:Refraction|refraction]] from sublunary material, citing his observation of the conjunction of Jupiter and Mars on 500 [[Engineering:Islamic calendar|AH]] (1106/1107 AD) as evidence.<ref name=Montada/><ref>{{cite book |at=Table 2.1, p. 25 |title=A history of physical theories of comets, from Aristotle to Whipple |author=Tofigh Heidarzadeh |publisher=Springer |year=2008 |isbn=978-1-4020-8322-8}}</ref> Ibn Qayyim Al-Jawziyya (1292–1350) proposed the Milky Way galaxy to be "a myriad of tiny stars packed together in the sphere of the fixed stars".<ref name=Livingston>{{Cite journal |last=Livingston |first=John W. |title=Ibn Qayyim al-Jawziyyah: A Fourteenth Century Defense against Astrological Divination and Alchemical Transmutation |journal=Journal of the American Oriental Society |volume=91 |issue=1 |year=1971 |pages=96–103 [99] |doi=10.2307/600445| jstor=600445}}</ref>

In the 10th century, the Persian astronomer Abd al-Rahman al-Sufi (known in the West as ''Azophi'') made the earliest recorded observation of the [[Astronomy:Andromeda Galaxy|Andromeda Galaxy]], describing it as a "small cloud".<ref>{{cite book |last1=Kepple |first1=George Robert |last2=Sanner |first2=Glen W. |title=The Night Sky Observer's Guide, Volume 1 |publisher=Willmann-Bell, Inc. |year=1998 |isbn=0-943396-58-1 |page=18}}</ref> Al-Sufi also identified the [[Astronomy:Large Magellanic Cloud|Large Magellanic Cloud]], which is visible from Yemen, though not from [[Place:Isfahan|Isfahan]]; it was not seen by Europeans until Magellan's voyage in the 16th century.<ref>{{cite web |publisher=Observatoire de Paris |title=Abd-al-Rahman Al Sufi (December 7, 903 - May 25, 986 A.D.) |url=http://messier.obspm.fr/xtra/Bios/alsufi.html |access-date=2007-04-19}}</ref><ref>{{cite web |publisher=Observatoire de Paris |title=The Large Magellanic Cloud, LMC |access-date=2007-04-19 |url=http://messier.obspm.fr/xtra/ngc/lmc.html}}</ref> These were the first galaxies other than the Milky Way to be observed from Earth. Al-Sufi published his findings in his ''[[Astronomy:Book of Fixed Stars|Book of Fixed Stars]]'' in 964.

===Possible worlds===
[[Biography:Al-Ghazali|Al-Ghazali]], in ''[[Religion:The Incoherence of the Philosophers|The Incoherence of the Philosophers]]'', defends the [[Religion:Ash'ari|Ash'ari]] doctrine of a created universe that is [[Temporal finitism|temporally finite]], against the [[Philosophy:Aristotelianism|Aristotelian]] doctrine of an [[Eternity|eternal]] universe. In doing so, he proposed the [[Philosophy:Modal realism|modal]] theory of [[Philosophy:Possible world|possible world]]s, arguing that their actual world is the [[Philosophy:Best of all possible worlds|best of all possible worlds]] from among all the alternate timelines and [[History:World history (field)|world histories]] that God could have possibly created. His theory parallels that of [[Biography:Duns Scotus|Duns Scotus]] in the 14th century. While it is uncertain whether Al-Ghazali had any influence on Scotus, they both may have derived their theory from their readings of [[Biography:Avicenna|Avicenna]]'s ''Metaphysics''.<ref>{{citation|title=Possible Worlds in the Tahâfut al-Falâsifa: Al-Ghazâlî on Creation and Contingency|author=Taneli Kukkonen|journal=[[Philosophy:Journal of the History of Philosophy|Journal of the History of Philosophy]]|volume=38|issue=4|year=2000|pages=479–502|doi=10.1353/hph.2005.0033|s2cid=170995877}}</ref>

===Multiversal cosmology===
[[File:Tusi couple.jpg|upright=1.15|thumb|right|The Tusi-couple is a mathematical device invented by Nasir al-Din al-Tusi in which a small [[Circle|circle]] rotates inside a larger circle twice the [[Diameter|diameter]] of the smaller [[Circle|circle]]. Rotations of the circles cause a point on the [[Circumference|circumference]] of the smaller circle to oscillate back and forth in linear motion along a diameter of the larger circle.]]

[[Biography:Fakhr al-Din al-Razi|Fakhr al-Din al-Razi]] (1149–1209), in dealing with his conception of physics and the physical world in his ''Matalib al-'Aliya'', criticizes the idea of the [[Geocentric model|Earth's centrality]] within the universe and "explores the notion of the existence of a [[Physics:Multiverse|multiverse]] in the context of his commentary" on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds." He raises the question of whether the term "[[Philosophy:World|world]]s" in this verse refers to "multiple worlds within this single [[Astronomy:Universe|universe]] or [[Astronomy:Cosmos|cosmos]], or to many other universes or a multiverse beyond this known universe." In volume 4 of the ''Matalib'', Al-Razi states:<ref name=Setia/>

{{Blockquote|It is established by evidence that there exists beyond the world a void without a terminal limit (''khala' la nihayata laha''), and it is established as well by evidence that God Most High has power over all contingent beings (''al-mumkinat''). Therefore He the Most High has the power (''qadir'') to create a thousand thousand worlds (''alfa alfi 'awalim'') beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has of the throne (''al-arsh''), the chair (''al-kursiyy''), the heavens (''al-samawat'') and the Earth (''al-ard''), and the Sun (''al-shams'') and the Moon (''al-qamar''). The arguments of the philosophers (''dala'il al-falasifah'') for establishing that the world is one are weak, flimsy arguments founded upon feeble premises.}}

Al-Razi rejected the [[Philosophy:Aristotelianism|Aristotelian]] and [[Religion:Avicennism|Avicennian]] notions of a single universe revolving around a single world. He describes the main arguments against the existence of multiple worlds or universes, pointing out their weaknesses and refuting them. This rejection arose from his affirmation of [[Philosophy:Atomism|atomism]], as advocated by the [[Religion:Ash'ari|Ash'ari]] school of Islamic theology, which entails the existence of vacant space in which the atoms move, combine and separate. He discussed in greater detail the [[Astronomy:Void|void]], the empty space between stars and constellations in the [[Astronomy:Universe|Universe]], in volume 5 of the ''Matalib''.<ref name=Setia/> He argued that there exists an infinite [[Astronomy:Outer space|outer space]] beyond the known world,<ref name=Iskenderoglu>{{citation|title=Fakhr al-Dīn al-Rāzī and Thomas Aquinas on the question of the eternity of the world|author=Muammer İskenderoğlu|publisher=[[Company:Brill Publishers|Brill Publishers]]|year=2002|isbn=90-04-12480-2|page=79}}</ref> and that God has the power to fill the [[Physics:Vacuum|vacuum]] with an infinite number of universes.<ref>{{citation|title=al-Razi, Fakhr al-Din (1149-1209)|encyclopedia=[[Routledge Encyclopedia of Philosophy]]|author=John Cooper|year=1998|publisher=[[Company:Routledge|Routledge]]|url=http://www.muslimphilosophy.com/ip/rep/H044.htm|access-date=2010-03-07}}</ref>

===Refutations of astrology===

The study of astrology was refuted by several Muslim writers at the time, including [[Biography:Al-Farabi|al-Farabi]], [[Biography:Ibn al-Haytham|Ibn al-Haytham]], [[Biography:Avicenna|Avicenna]], Biruni and [[Biography:Averroes|Averroes]].{{additional citation needed|date=October 2016}} Their reasons for refuting astrology were often due to both scientific (the methods used by astrologers being conjectural rather than empirical) and religious (conflicts with orthodox Islamic scholars) reasons.<ref>{{Harv|Saliba|1994b|pp=60, 67–69}}</ref>

Ibn Qayyim Al-Jawziyya (1292–1350), in his ''Miftah Dar al-SaCadah'', used empirical arguments in astronomy in order to refute the practice of astrology and divination.<ref name=Livingston/> He recognized that the [[Astronomy:Star|star]]s are much larger than the [[Astronomy:Planet|planet]]s, and thus argued:<ref name=Livingston/>
{{Blockquote|"And if you astrologers answer that it is precisely because of this distance and smallness that their influences are negligible, then why is it that you claim a great influence for the smallest heavenly body, Mercury? Why is it that you have given an influence to al-Ra's and al-Dhanab, which are two imaginary points [ascending and descending nodes]?"}}

Al-Jawziyya also recognized the [[Astronomy:Milky Way|Milky Way]] [[Astronomy:Galaxy|galaxy]] as "a myriad of tiny stars packed together in the sphere of the fixed stars" and thus argued that "it is certainly impossible to have knowledge of their influences."<ref name=Livingston/>

===Early heliocentric models===
[[File:Birjandimanuscript.jpg|thumb|upright=0.85|right|A work of [[Biography:Al-Birjandi|Al-Birjandi]]'s, Sharh al-Tadhkirah, a manuscript copy, beginning of 17th Century]]

The [[Astronomy:Ancient Greek astronomy|Hellenistic Greek astronomer]] [[Biography:Seleucus of Seleucia|Seleucus of Seleucia]], who advocated a [[Astronomy:Heliocentrism|heliocentric]] model in the 2nd century BC, wrote a work that was later translated into Arabic. A fragment of his work has survived only in Arabic translation, which was later referred to by the Persian philosopher [[Biography:Muhammad ibn Zakariya al-Razi|Muhammad ibn Zakariya al-Razi]] (865–925).<ref>{{citation|title=Studies in Arabic versions of Greek texts and in mediaeval science|volume=2|author=Shlomo Pines|publisher=[[Company:Brill Publishers|Brill Publishers]]|year=1986|isbn=965-223-626-8|pages=viii & 201–217|}}</ref>

In the late ninth century, Ja'far ibn Muhammad Abu Ma'shar al-Balkhi (Albumasar) developed a planetary model which some have interpreted as a [[Astronomy:Heliocentrism|heliocentric model]]. This is due to his [[Physics:Orbit|orbit]]al revolutions of the planets being given as heliocentric revolutions rather than [[Geocentric model|geocentric]] revolutions, and the only known planetary theory in which this occurs is in the heliocentric theory. His work on planetary theory has not survived, but his astronomical data was later recorded by al-Hashimi, Abū Rayhān al-Bīrūnī and [[Biography:Al-Sijzi|al-Sijzi]].<ref>{{cite journal |last1=van der Waerden |first1=Bartel Leendert |year=1987 |title=The Heliocentric System in Greek, Persian and Hindu Astronomy |doi=10.1111/j.1749-6632.1987.tb37224.x |journal=Annals of the New York Academy of Sciences |volume=500 |issue=1| pages=525–545 [534–537] |bibcode=1987NYASA.500..525V |s2cid=222087224}}</ref>

In the early eleventh century, [[Biography:Al-Biruni|al-Biruni]] had met several Indian scholars who believed in a rotating Earth. In his ''Indica'', he discusses the theories on the [[Earth's rotation]] supported by Brahmagupta and other [[Astronomy:Indian astronomy|Indian astronomers]], while in his ''Canon Masudicus'', al-Biruni writes that Aryabhata's followers assigned the first movement from east to west to the Earth and a second movement from west to east to the fixed stars. Al-Biruni also wrote that [[Biography:Al-Sijzi|al-Sijzi]] also believed the Earth was moving and invented an [[Astronomy:Astrolabe|astrolabe]] called the "Zuraqi" based on this idea:<ref name=Nasr>{{Harv|Nasr|1993|pp=135–136}}</ref>

{{Blockquote|"I have seen the astrolabe called Zuraqi invented by Abu Sa'id Sijzi. I liked it very much and praised him a great deal, as it is based on the idea entertained by some to the effect that the motion we see is due to the Earth's   movement and not to that of the sky. By my life, it is a problem difficult of solution and refutation. [...] For it is the same whether you take it that the Earth is in motion or the sky. For, in both cases, it does not affect the Astronomical Science. It is just for the physicist to see if it is possible to refute it."}}

In his ''Indica'', al-Biruni briefly refers to his work on the refutation of heliocentrism, the ''Key of Astronomy'', which is now lost:<ref name=Nasr/>

{{Blockquote|"The most prominent of both modern and ancient astronomers have deeply studied the question of the moving earth, and tried to refute it. We, too, have composed a book on the subject called ''Miftah 'ilm al-hai'ah'' (''Key of Astronomy''), in which we think we have surpassed our predecessors, if not in the words, at all events in the matter."}}

===Early ''Hay'a'' program===
[[File:Timbuktu-manuscripts-astronomy-mathematics.jpg|thumb|left|The Timbuktu Manuscripts showing both [[Mathematics|mathematics]] and astronomy.]]

During this period, a distinctive Islamic system of astronomy flourished.  It was Greek tradition to separate mathematical astronomy (as typified by [[Biography:Ptolemy|Ptolemy]]) from philosophical cosmology (as typified by [[Biography:Aristotle|Aristotle]]). Muslim scholars developed a program of seeking a physically real configuration (''hay'a'') of the universe, that would be consistent with both [[Mathematics|mathematical]] and [[Physics:Physics|physical]] principles.  Within the context of this ''hay'a'' tradition, Muslim astronomers began questioning technical details of the Ptolemaic system of astronomy.<ref>{{Harv|Sabra|1998|pp=293–298}}</ref>

Some Muslim astronomers, however, most notably Abū Rayhān al-Bīrūnī and Nasīr al-Dīn al-Tūsī, discussed whether the Earth moved and considered how this might be consistent with astronomical computations and physical systems.<ref>{{Harv|Ragep|Teresi|Hart|2002}}</ref> Several other Muslim astronomers, most notably those following the Maragha school of astronomy, developed non-Ptolemaic planetary models within a geocentric context that were later adapted by the [[Astronomy:Copernican heliocentrism|Copernican model]] in a [[Astronomy:Heliocentrism|heliocentric]] context.

Between 1025 and 1028, [[Biography:Ibn al-Haytham|Ibn al-Haytham]] ([[Social:Latin|Latin]]ized as Alhazen), began the ''hay'a'' tradition of Islamic astronomy with his ''Al-Shuku ala Batlamyus'' (''Doubts on Ptolemy''). While maintaining the physical reality of the [[Geocentric model|geocentric model]], he was the first to criticize [[Biography:Ptolemy|Ptolemy]]'s astronomical system, which he criticized on empirical, [[Observation|observation]]al and [[Experiment|experiment]]al grounds,<ref>{{Harv|Sabra|1998|p=300}}</ref> and for relating actual physical motions to imaginary mathematical points, lines and circles.<ref>{{citation|contribution-url=http://setis.library.usyd.edu.au/stanford/entries/copernicus/index.html
|contribution=Nicolaus Copernicus|title=Stanford Encyclopedia of Philosophy|year=2004|access-date=2008-01-22|title-link=Stanford Encyclopedia of Philosophy}}</ref> Ibn al-Haytham developed a physical structure of the Ptolemaic system in his ''Treatise on the configuration of the World'', or ''Maqâlah fî ''hay'at'' al-‛âlam'', which became an influential work in the ''hay'a'' tradition.<ref>{{Harv|Langermann|1990|pp=25–34}}</ref> In his ''Epitome of Astronomy'', he insisted that the heavenly bodies "were accountable to the [[Physical law|laws of physics]]."<ref>{{Harv|Duhem|1969|p=28}}</ref>

In 1038, Ibn al-Haytham described the first non-Ptolemaic configuration in ''The Model of the Motions''. His reform was not concerned with [[Astronomy:Cosmology|cosmology]], as he developed a systematic study of celestial [[Physics:Kinematics|kinematics]] that was completely [[Geometry|geometric]]. This in turn led to innovative developments in [[Infinitesimal|infinitesimal]] [[Geometry|geometry]].<ref>{{Harv|Rashed|2007}}</ref> His reformed model was the first to reject the [[Equant|equant]]<ref>{{Harv|Rashed|2007|pp=20 & 53}}</ref> and eccentrics,<ref>{{Harv|Rashed|2007|pp=33–4}}</ref> separate [[Philosophy:Natural philosophy|natural philosophy]] from astronomy, free celestial kinematics from cosmology, and reduce physical entities to geometrical entities. The model also propounded the [[Earth's rotation]] about its axis,<ref>{{Harv|Rashed|2007|pp=20 & 32–33}}</ref> and the centres of motion were geometrical points without any physical significance, like [[Biography:Johannes Kepler|Johannes Kepler]]'s model centuries later.<ref>{{Harv|Rashed|2007|pp=51–2}}</ref> Ibn al-Haytham also describes an early version of [[Occam's razor]], where he employs only minimal hypotheses regarding the properties that characterize astronomical motions, as he attempts to eliminate from his planetary model the [[Astronomy:Cosmology|cosmological]] hypotheses that cannot be observed from [[Astronomy:Earth|Earth]].<ref>{{Harv|Rashed|2007|pp=35–36}}</ref>

In 1030, Abū al-Rayhān al-Bīrūnī discussed the [[Astronomy:Indian astronomy|Indian planetary theories]] of Aryabhata, Brahmagupta and Varahamihira in his ''Ta'rikh al-Hind'' (Latinized as ''Indica''). Biruni stated that Brahmagupta and others consider that the [[Earth's rotation|earth rotates]] on its axis and Biruni noted that this does not create any mathematical problems.<ref>{{Harv|Nasr|1993|p=135, n. 13}}</ref> Abu Said [[Biography:Al-Sijzi|al-Sijzi]], a contemporary of al-Biruni, suggested the possible heliocentric movement of the Earth around the Sun, which al-Biruni did not reject.<ref name=Ahmad>{{Harv|Ahmad|1966}}</ref> Al-Biruni agreed with the [[Earth's rotation]] about its own axis, and while he was initially neutral regarding the [[Astronomy:Heliocentrism|heliocentric]] and [[Geocentric model|geocentric model]]s,<ref>{{Harv|Marmura|1965}}</ref> he considered heliocentrism to be a philosophical problem.<ref name=Saliba/> He remarked that if the Earth rotates on its axis and moves around the Sun, it would remain consistent with his astronomical parameters:<ref name=Khwarizm>{{cite web|url=http://muslimheritage.com/topics/default.cfm?ArticleID=482 |title=Khwarizm|publisher=Foundation for Science Technology and Civilisation|access-date=2008-01-22 |archive-url=https://web.archive.org/web/20100104101845/http://muslimheritage.com/topics/default.cfm?ArticleID=482 |archive-date=2010-01-04|url-status=dead}}</ref><ref>{{Harv|Saliba|1980|p=249}}</ref><ref>G. Wiet, V. Elisseeff, P. Wolff, J. Naudu (1975). ''History of Mankind, Vol 3: The Great medieval Civilisations'', p. 649. George Allen & Unwin Ltd, [[Organization:UNESCO|UNESCO]].</ref>
{{Blockquote|"Rotation of the earth would in no way invalidate astronomical calculations, for all the astronomical data are as explicable in terms of the one theory as of the other. The problem is thus difficult of solution."}}

===Andalusian Revolt===
[[File:AverroesColor.jpg|thumb|Averroes rejected the eccentric deferents introduced by Ptolemy. He rejected the Ptolemaic model and instead argued for a strictly concentric model of the universe.]]

In the 11th–12th centuries, astronomers in al-Andalus took up the challenge earlier posed by Ibn al-Haytham, namely to develop an alternate non-Ptolemaic configuration that evaded the errors found in the [[Geocentric model|Ptolemaic model]].<ref>{{Harv|Saliba|1981|p=219}}</ref> Like Ibn al-Haytham's critique, the anonymous Andalusian work, ''al-Istidrak ala Batlamyus'' (''Recapitulation regarding Ptolemy''), included a list of objections to Ptolemic astronomy. This marked the beginning of the Andalusian school's revolt against Ptolemaic astronomy, otherwise known as the "Andalusian Revolt".<ref>{{citation|first=A. I.|last=Sabra|contribution=The Andalusian Revolt Against Ptolemaic Astronomy: Averroes and al-Bitrûjî|pages=233–53|editor-first=Everett|editor-last=Mendelsohn|title=Transformation and Tradition in the Sciences: Essays in honor of I. Bernard Cohen|publisher={{wipe|Cambridge University Press}}}}</ref>

In the 12th century, [[Biography:Averroes|Averroes]] rejected the [[Astronomy:Deferent and epicycle|eccentric deferents]] introduced by [[Biography:Ptolemy|Ptolemy]]. He rejected the Ptolemaic model and instead argued for a strictly concentric model of the universe. He wrote the following criticism on the Ptolemaic model of planetary motion:<ref name=Gingerich>{{Citation|last=Gingerich |first=Owen |date=April 1986 |url=http://faculty.kfupm.edu.sa/PHYS/alshukri/PHYS215/Islamic_astronomy.htm |title=Islamic astronomy |journal=Scientific American |volume=254 |issue=10 |page=74 |access-date=2008-05-18 |doi=10.1038/scientificamerican0486-74 |bibcode=1986SciAm.254d..74G |url-status=dead |archive-url=https://web.archive.org/web/20110101211150/http://faculty.kfupm.edu.sa/PHYS/alshukri/PHYS215/Islamic_astronomy.htm |archive-date=2011-01-01 }}</ref>

{{Blockquote|"To assert the existence of an eccentric sphere or an epicyclic sphere is contrary to nature. [...] The astronomy of our time offers no truth, but only agrees with the calculations and not with what exists."}}

Averroes' contemporary, [[Biography:Maimonides|Maimonides]], wrote the following on the planetary model proposed by Ibn Bajjah (Avempace):

{{Blockquote|"I have heard that Abu Bakr [Ibn Bajja] discovered a system in which no [[Astronomy:Deferent and epicycle|epicycles]] occur, but [[Eccentricity (mathematics)|eccentric]] spheres are not excluded by him. I have not heard it from his pupils; and even if it be correct that he discovered such a system, he has not gained much by it, for eccentricity is likewise contrary to the principles laid down by Aristotle.... I have explained to you that these difficulties do not concern the astronomer, for he does not profess to tell us the existing properties of the spheres, but to suggest, whether correctly or not, a theory in which the motion of the [[Astronomy:Star|star]]s and planets is uniform and circular, and in agreement with observation."<ref>{{cite journal | last1 = Goldstein | first1 = Bernard R. | year = 1972 | title = Theory and Observation in Medieval Astronomy | journal = Isis | volume = 63 | issue = 1| pages = 39–47 [40–41] | doi = 10.1086/350839 | s2cid = 120700705 }}</ref>}}

Ibn Bajjah also proposed the [[Astronomy:Milky Way|Milky Way]] [[Astronomy:Galaxy|galaxy]] to be made up of many stars but that it appears to be a continuous image due to the effect of [[Physics:Refraction|refraction]] in the Earth's atmosphere.<ref name=Montada>{{cite encyclopedia|author=Josep Puig Montada|title=Ibn Bajja|encyclopedia=[[Stanford Encyclopedia of Philosophy]]|url=http://plato.stanford.edu/entries/ibn-bajja|date=September 28, 2007|access-date=2008-07-11}}</ref> Later in the 12th century, his successors [[Biography:Ibn Tufail|Ibn Tufail]] and Nur Ed-Din Al Betrugi (Alpetragius) were the first to propose planetary models without any [[Equant|equant]], [[Astronomy:Deferent and epicycle|epicycles or eccentrics]]. Their configurations, however, were not accepted due to the numerical predictions of the planetary positions in their models being less accurate than that of the Ptolemaic model,<ref name=Gale>{{citation|url=http://www.bookrags.com/research/ptolemaic-astronomy-islamic-planeta-scit-021234
|contribution=Ptolemaic Astronomy, Islamic Planetary Theory, and Copernicus's Debt to the Maragha School|title=Science and Its Times|publisher=Thomson Gale|year=2005–2006|access-date=2008-01-22}}</ref> mainly because they followed [[Biography:Aristotle|Aristotle]]'s notion of perfectly uniform circular motion.

===Maragha Revolution===

The "Maragha Revolution" refers to the Maragheh school's [[Social:Revolution|revolution]] against Ptolemaic astronomy. The "Maragha school" was an astronomical tradition beginning in the Maragheh observatory and continuing with astronomers from [[Place:Damascus|Damascus]] and [[Place:Samarkand|Samarkand]]. Like their Andalusian predecessors, the Maragha astronomers attempted to solve the [[Equant|equant]] problem and produce alternative configurations to the Ptolemaic model. They were more successful than their Andalusian predecessors in producing non-Ptolemaic configurations which eliminated the equant and eccentrics, were more accurate than the Ptolemaic model in numerically predicting planetary positions, and were in better agreement with empirical [[Observation|observation]]s.<ref name=Saliba-1994>{{Harv|Saliba|1994b|pp=233–234, 240}}</ref> The most important of the Maragha astronomers included Mo'ayyeduddin Urdi (d. 1266), Nasīr al-Dīn al-Tūsī (1201–1274), [[Biography:Najm al-Dīn al-Qazwīnī al-Kātibī|Najm al-Dīn al-Qazwīnī al-Kātibī]] (d. 1277), [[Biography:Qutb al-Din al-Shirazi|Qutb al-Din al-Shirazi]] (1236–1311), Sadr al-Sharia al-Bukhari (c. 1347), Ibn al-Shatir (1304–1375), [[Biography:Ali Qushji|Ali Qushji]] (c. 1474), [[Biography:Al-Birjandi|al-Birjandi]] (d. 1525) and Shams al-Din al-Khafri (d. 1550).<ref>{{Harv|Dallal|1999|p=171}}</ref>

Some have described their achievements in the 13th and 14th centuries as a "Maragha Revolution", "Maragha School Revolution", or "Scientific Revolution before the [[Philosophy:Renaissance|Renaissance]]".  An important aspect of this revolution included the realization that astronomy should aim to describe the behavior of [[Philosophy:Physical body|physical bodies]] in mathematical language, and should not remain a mathematical [[Hypothesis|hypothesis]], which would only save the phenomena. The Maragha astronomers also realized that the [[Astronomy:On the Heavens|Aristotelian]] view of [[Physics:Motion|motion]] in the universe being only circular or linear was not true, as the Tusi-couple showed that linear motion could also be produced by applying [[Physics:Circular motion|circular motion]]s only.<ref>{{Harv|Saliba|1994b|pp=245, 250, 256–257}}</ref>

Unlike the ancient Greek and Hellenistic astronomers who were not concerned with the coherence between the mathematical and physical principles of a planetary theory, Islamic astronomers insisted on the need to match the mathematics with the real world surrounding them,<ref>{{Harv|Saliba|1999a}}</ref> which gradually evolved from a reality based on [[Physics:Aristotelian physics|Aristotelian physics]] to one based on an empirical and mathematical [[Physics:Physics|physics]] after the work of Ibn al-Shatir. The Maragha Revolution was thus characterized by a shift away from the philosophical foundations of [[Astronomy:On the Heavens|Aristotelian cosmology]] and Ptolemaic astronomy and towards a greater emphasis on the empirical observation and mathematization of astronomy and of [[Earth:Nature|nature]] in general, as exemplified in the works of Ibn al-Shatir, Qushji, al-Birjandi and al-Khafri.<ref>{{Harv|Saliba|1994b|pp=42 & 80}}</ref><ref>{{citation|first=Ahmad|last=Dallal|year=2001–2002|title=The Interplay of Science and Theology in the Fourteenth-century Kalam|publisher=From Medieval to Modern in the Islamic World, Sawyer Seminar at the [[Organization:University of Chicago|University of Chicago]] |url=http://humanities.uchicago.edu/orgs/institute/sawyer/archive/islam/dallal.html|access-date=2008-02-02 |archive-url=https://web.archive.org/web/20120210094416/http://humanities.uchicago.edu/orgs/institute/sawyer/archive/islam/dallal.html |archive-date=2012-02-10|url-status=dead}}</ref><ref>{{Harv|Huff|2003|pp=217–218}}</ref>

[[File:Shatir500.jpg|thumb|right|Ibn al-Shatir's model for the appearances of Mercury, showing the multiplication of epicycles using the Tusi-couple, thus eliminating the Ptolemaic eccentrics and [[Equant|equant]].]]

Other achievements of the Maragha school include the first empirical observational evidence for the [[Earth's rotation]] on its axis by al-Tusi and Qushji,<ref name=Ragep/> the separation of [[Philosophy:Natural philosophy|natural philosophy]] from astronomy by Ibn al-Shatir and Qushji,<ref name=Ragep2>{{Harv|Ragep|2001b}}</ref> the rejection of the Ptolemaic model on empirical rather than philosophical grounds by Ibn al-Shatir,<ref name=Saliba-1994/> and the development of a non-Ptolemaic model by Ibn al-Shatir that was mathematically identical to the [[Astronomy:Copernican heliocentrism|heliocentric Copernical model]].<ref>{{Harv|Saliba|1994b|pp=254, 256–257}}</ref>

Mo'ayyeduddin Urdi (d. 1266)  was the first of the Maragheh astronomers to develop a non-Ptolemaic model, and he proposed a new theorem, the "Urdi lemma".<ref>{{Harv|Saliba|1979}}</ref> Nasīr al-Dīn al-Tūsī (1201–1274) resolved significant problems in the Ptolemaic system by developing the Tusi-couple as an alternative to the physically problematic [[Equant|equant]] introduced by Ptolemy.<ref name=Gill>{{Harv|Gill|2005}}</ref> Tusi's student [[Biography:Qutb al-Din al-Shirazi|Qutb al-Din al-Shirazi]] (1236–1311), in his ''The Limit of Accomplishment concerning Knowledge of the Heavens'', discussed the possibility of [[Astronomy:Heliocentrism|heliocentrism]]. Al-Qazwīnī al-Kātibī, who also worked at the Maragheh observatory, in his ''Hikmat al-'Ain'', wrote an argument for a heliocentric model, though he later abandoned the idea.<ref name=Ahmad/>

[[File:Ghotb2.jpg|thumb|upright=0.85|left|Medieval manuscript by Qutb al-Din al-Shirazi depicting an epicyclic planetary model.]]

Ibn al-Shatir (1304–1375) of [[Place:Damascus|Damascus]], in ''A Final Inquiry Concerning the Rectification of Planetary Theory'', incorporated the Urdi lemma, and eliminated the need for an equant by introducing an extra epicycle (the Tusi-couple), departing from the Ptolemaic system in a way that was mathematically identical to what [[Biography:Nicolaus Copernicus|Nicolaus Copernicus]] did in the 16th century. Unlike previous astronomers before him, Ibn al-Shatir was not concerned with adhering to the theoretical principles of [[Philosophy:Natural philosophy|natural philosophy]] or Aristotelian [[Astronomy:Cosmology|cosmology]], but rather to produce a model that was more consistent with empirical observations. For example, it was Ibn al-Shatir's concern for observational accuracy which led him to eliminate the epicycle in the Ptolemaic [[Astronomy:Sun|solar]] model and all the eccentrics, epicycles and equant in the Ptolemaic [[Astronomy:Moon|lunar]] model. His model was thus in better agreement with empirical [[Observation|observation]]s than any previous model,<ref name=Saliba-1994/> and was also the first that permitted empirical [[Experiment|testing]].<ref>{{cite journal | last1 = Faruqi | first1 = Y. M. | year = 2006 | title = Contributions of Islamic scholars to the scientific enterprise | journal = International Education Journal | volume = 7 | issue = 4| pages = 395–396 }}</ref> His work thus marked a turning point in astronomy, which may be considered a "Scientific Revolution before the Renaissance".<ref name=Saliba-1994/> His rectified model was later adapted into a [[Astronomy:Copernican heliocentrism|heliocentric model]] by Copernicus,<ref name=Gill/> which was mathematically achieved by reversing the direction of the last vector connecting the Earth to the Sun.<ref name=Saliba>{{Harv|Saliba|1999}}</ref>

An area of active discussion in the Maragheh school, and later the [[Place:Samarkand|Samarkand]] and Istanbul observatories, was the possibility of the [[Earth's rotation]]. Supporters of this theory included Nasīr al-Dīn al-Tūsī, Nizam al-Din al-Nisaburi (c. 1311), al-Sayyid al-Sharif al-Jurjani (1339–1413), Ali Qushji (d. 1474), and Abd al-Ali [[Biography:Al-Birjandi|al-Birjandi]] (d. 1525). Al-Tusi was the first to present empirical observational evidence of the Earth's rotation, using the location of [[Astronomy:Comet|comet]]s relevant to the Earth as evidence, which Qushji elaborated on with further empirical observations while rejecting Aristotelian [[Philosophy:Natural philosophy|natural philosophy]] altogether. Both of their arguments were similar to the arguments later used by [[Biography:Nicolaus Copernicus|Nicolaus Copernicus]] in 1543 to explain the Earth's rotation (see Astronomical physics and Earth's motion section below).<ref name=Ragep>{{Harv|Ragep|2001a}}</ref>

===Experimental astrophysics and celestial mechanics===
In the 9th century, the eldest [[Biography:Banū Mūsā|Banū Mūsā]] brother, Ja'far Muhammad ibn Mūsā ibn Shākir, made significant contributions to Islamic astrophysics and [[Physics:Celestial mechanics|celestial mechanics]]. He was the first to hypothesize that the heavenly bodies and [[Astronomy:Celestial spheres|celestial spheres]] are subject to the same [[Physical law|laws of physics]] as [[Astronomy:Earth|Earth]], unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth.<ref>{{Harv|Saliba|1994a|p=116}}</ref> In his ''Astral Motion'' and ''The Force of Attraction'', Muhammad ibn Musa also proposed that there is a [[Physics:Force|force]] of attraction between [[Astronomy:Astronomical object|heavenly bodies]],<ref>{{citation|first=K. A.|last=Waheed|year=1978|title=Islam and The Origins of Modern Science|page=27|publisher=Islamic Publication Ltd., Lahore}}</ref> foreshadowing [[Physics:Newton's law of universal gravitation|Newton's law of universal gravitation]].<ref>{{Harv|Briffault|1938|p=191}}</ref>

In the early 11th century, [[Biography:Ibn al-Haytham|Ibn al-Haytham]] (Alhazen) wrote the ''Maqala fi daw al-qamar'' (''On the Light of the Moon'') some time before 1021. This was the first attempt successful at combining mathematical astronomy with [[Physics:Physics|physics]] and the earliest attempt at applying the [[Scientific method|experimental method]] to astronomy and [[Physics:Astrophysics|astrophysics]]. He disproved the universally held opinion that the [[Astronomy:Moon|Moon]] reflects [[Astronomy:Sunlight|sunlight]] like a [[Physics:Mirror|mirror]] and correctly concluded that it "emits light from those portions of its surface which the [[Astronomy:Sun|sun]]'s light strikes." In order to prove that "light is emitted from every point of the Moon's illuminated surface," he built an "ingenious [[Experiment|experiment]]al device." Ibn al-Haytham had "formulated a clear conception of the relationship between an ideal mathematical model and the complex of observable phenomena; in particular, he was the first to make a systematic use of the method of varying the experimental conditions in a constant and uniform manner, in an experiment showing that the [[Physics:Radiance|intensity]] of the light-spot formed by the projection of the [[Astronomy:Moonlight|moonlight]] through two small [[Astronomy:Aperture|aperture]]s onto a screen diminishes constantly as one of the apertures is gradually blocked up."<ref name=Toomer>{{citation|first=G. J.|last=Toomer|title=Review: ''Ibn al-Haythams Weg zur Physik'' by Matthias Schramm|journal=Isis|volume=55|issue=4|date=December 1964|pages=463–465 [463–4]|doi=10.1086/349914}}</ref>

Ibn al-Haytham, in his ''[[Physics:Book of Optics|Book of Optics]]'' (1021), was also the first to discover that the [[Astronomy:Celestial spheres|celestial spheres]] do not consist of [[Physics:Solid|solid]] matter, and he also discovered that the heavens are less dense than the air. These views were later repeated by Witelo and had a significant influence on the [[Astronomy:Copernican heliocentrism|Copernican]] and [[Astronomy:Tychonic system|Tychonic system]]s of astronomy.<ref>{{Harv|Rosen|1985|pp=19–21}}</ref>

In the 12th century, [[Biography:Fakhr al-Din al-Razi|Fakhr al-Din al-Razi]] participated in the debate among Islamic scholars over whether the [[Astronomy:Celestial spheres|celestial spheres]] or orbits (''falak'') are "to be considered as real, concrete physical bodies" or "merely the abstract circles in the heavens traced out year in and year out by the various stars and planets." He points out that many astronomers prefer to see them as solid spheres "on which the stars turn," while others, such as the Islamic scholar Dahhak, view the celestial sphere as "not a body but merely the abstract orbit traced by the stars." Al-Razi himself remains "undecided as to which [[Physics:Celestial mechanics|celestial models]], concrete or abstract, most conform with external reality," and notes that "there is no way to ascertain the characteristics of the heavens," whether by "observable" evidence or by authority (''al-khabar'') of "divine revelation or [[Religion:Sunnah|prophetic traditions]]." He concludes that "astronomical models, whatever their utility or lack thereof for ordering the heavens, are not founded on sound rational proofs, and so no intellectual commitment can be made to them insofar as description and explanation of celestial realities are concerned."<ref name=Setia/>

The theologian Adud al-Din al-Iji (1281–1355), under the influence of the [[Religion:Ash'ari|Ash'ari]] doctrine of [[Philosophy:Occasionalism|occasionalism]], which maintained that all physical effects were caused directly by God's will rather than by natural causes, rejected the [[Physics:Aristotelian physics|Aristotelian principle]] of an innate principle of circular motion in the heavenly bodies,<ref>{{Harv|Huff|2003|p=175}}</ref> and maintained that the celestial spheres were "imaginary things" and "more tenuous than a spider's web".<ref name=Ragep2/> His views were challenged by al-Jurjani (1339–1413), who argued that even if the celestial spheres "do not have an external reality, yet they are things that are correctly imagined and correspond to what [exists] in actuality".<ref name=Ragep2 />

===Astronomical physics and Earth's motion===
[[File:Ali Kuşçu Portre.jpg|thumb|upright=0.85|Ali Qushji provided [[Empirical research|empirical evidence]] for the [[Earth's rotation|Earth's motion]] and developed an astronomical physics independent from Aristotelian physics and natural philosophy.]]

The work of [[Biography:Ali Qushji|Ali Qushji]] (d. 1474), who worked at [[Place:Samarkand|Samarkand]] and then Istanbul, is seen as a late example of innovation in Islamic theoretical astronomy and it is believed he may have possibly had some influence on [[Biography:Nicolaus Copernicus|Nicolaus Copernicus]] due to similar arguments concerning the [[Earth's rotation]]. Before Qushji, the only astronomer to present [[Empirical research|empirical evidence]] for the Earth's rotation was Nasīr al-Dīn al-Tūsī (d. 1274), who used the phenomena of [[Astronomy:Comet|comet]]s to refute [[Biography:Ptolemy|Ptolemy]]'s claim that a stationary Earth can be determined through observation. Al-Tusi, however, eventually accepted that the Earth was stationary on the basis of [[Astronomy:On the Heavens|Aristotelian cosmology]] and [[Philosophy:Natural philosophy|natural philosophy]]. By the 15th century, the influence of [[Physics:Aristotelian physics|Aristotelian physics]] and natural philosophy was declining due to religious opposition from Islamic theologians such as [[Biography:Al-Ghazali|Al-Ghazali]] who opposed to the interference of [[Philosophy:Aristotelianism|Aristotelianism]] in astronomy, opening up possibilities for an astronomy unrestrained by philosophy. Under this influence, Qushji, in his ''Concerning the Supposed Dependence of Astronomy upon Philosophy'', rejected Aristotelian physics and completely separated natural philosophy from astronomy, allowing astronomy to become a purely empirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationary Earth, as he explored the idea of a moving Earth. He also observed comets and elaborated on al-Tusi's argument. He took it a step further and concluded, on the basis of empirical evidence rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory and that it is not possible to empirically deduce which theory is true.<ref name=Ragep/><ref name=Ragep2/><ref>Edith Dudley Sylla, "Creation and nature", in Arthur Stephen McGrade (2003), pp. 178–179, {{wipe|Cambridge University Press}}, {{ISBN|0-521-00063-7}}.</ref> His work was an important step away from Aristotelian physics and towards an independent [[Physics:Astrophysics|astronomical physics]].<ref>{{Harv|Ragep|2004|p=139}}</ref>

Despite the similarity in their discussions regarding the Earth's motion, there is uncertainty over whether Qushji had any influence on Copernicus. However, it is likely that they both may have arrived at similar conclusions due to using the earlier work of al-Tusi as a basis. This is more of a possibility considering "the remarkable coincidence between a passage in ''De revolutionibus'' (I.8) and one in Ṭūsī’s ''Tadhkira'' (II.1[6]) in which Copernicus follows Ṭūsī’s objection to Ptolemy’s “proofs” of the Earth's immobility." This can be considered as evidence that not only was Copernicus influenced by the mathematical models of Islamic astronomers, but may have also been influenced by the astronomical physics they began developing and their views on the Earth's motion.<ref>{{Harv|Ragep|2004|pp=137–139}}</ref>

In the 16th century, the debate on the Earth's motion was continued by [[Biography:Al-Birjandi|al-Birjandi]] (d. 1528), who in his analysis of what might occur if the Earth were moving, develops a hypothesis similar to [[Biography:Galileo Galilei|Galileo Galilei]]'s notion of "circular [[Physics:Inertia|inertia]]",<ref>{{Harv|Ragep|2001b|pp=63–64}}</ref> which he described in the following observational test (as a response to one of [[Biography:Qutb al-Din al-Shirazi|Qutb al-Din al-Shirazi]]'s arguments):

{{Blockquote|"The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (''sath'') of the horizon; this is witnessed by experience (''tajriba''). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (''hissi'') horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks."<ref>{{Harv|Ragep|2001a|pp=152–153}}</ref>}}

==See also==
* [[Religion:Sufi cosmology|Sufi cosmology]]
* [[Religion:Astronomy in the medieval Islamic world|Astronomy in the medieval Islamic world]]
* [[Religion:Baháʼí cosmology|Baháʼí cosmology]]
* [[Philosophy:Buddhist cosmology|Buddhist cosmology]]
* [[Unsolved:Biblical cosmology|Biblical cosmology]]
* [[Unsolved:Hindu cosmology|Hindu cosmology]]
* [[Religion:Jain cosmology|Jain cosmology]]
* [[Unsolved:Religious cosmology|Religious cosmology]]
* [[Religion:Arcs of Descent and Ascent|Arcs of Descent and Ascent]]

==Notes==
{{Reflist|2}}

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==External links==
*[http://www.alislam.org/library/books/revelation/part_4_section_5.html The Quran and Cosmology]
*Dr Israr Ahmed [https://web.archive.org/web/20080329114424/http://islam.islamabad.net/]


[[Category:Islamic cosmology| ]]

{{Sourceattribution|Cosmology in medieval Islam}}