Editing Scientific Revolution (section)

=== Astronomy ===

==== Heliocentrism ====
For almost five millennia, the [[geocentric model]] of the Earth as the center of the universe had been accepted by all but a few astronomers. In Aristotle's cosmology, Earth's central location was perhaps less significant than its identification as a realm of imperfection, inconstancy, irregularity, and change, as opposed to the "heavens" (Moon, Sun, planets, stars), which were regarded as perfect, permanent, unchangeable, and in religious thought, the realm of heavenly beings. The Earth was even composed of different material, the four elements "earth", "water", "fire", and "air", while sufficiently far above its surface (roughly the Moon's orbit), the heavens were composed of a different substance called "aether".<ref>{{citation |last1=Lewis |first1=C.S. |title=The Discarded Image |publisher=Canto Classics |isbn=978-1-107-60470-4 |year=2012 |pages=3, 4 }}</ref> The heliocentric model that replaced it involved the radical displacement of the Earth to an orbit around the Sun; sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

[[File:JKepler.jpg|thumb|left|Portrait of [[Johannes Kepler]], one of the founders and fathers of modern [[astronomy]], the [[scientific method]], [[Natural science|natural]] and [[modern science]]<ref>{{cite web | url=https://www.dpma.de/english/our_office/publications/milestones/greatinventors/johanneskepler/index.html | title=DPMA &#124; Johannes Kepler }}</ref><ref>{{Cite web |url=https://www.nasa.gov/kepler/education/johannes |title=Johannes Kepler: His Life, His Laws and Times &#124; NASA |access-date=1 September 2023 |archive-date=24 June 2021 |archive-url=https://web.archive.org/web/20210624003856/https://www.nasa.gov/kepler/education/johannes/ |url-status=dead }}</ref><ref>{{cite web | url=https://micro.magnet.fsu.edu/optics/timeline/people/kepler.html | title=Molecular Expressions: Science, Optics and You - Timeline - Johannes Kepler }}</ref>]]

Copernicus' 1543 work on the heliocentric model of the [[Solar System]] tried to demonstrate that the Sun was the center of the universe. Few were bothered by this suggestion, and the pope and several archbishops were interested enough by it to want more detail.<ref>[[#Hannam|Hannam]], p. 303</ref> His model was later used to create [[Gregorian calendar|the calendar]] of [[Pope Gregory XIII]].<ref>[[#Hannam|Hannam]], p. 329</ref> However, the idea that the Earth moved around the Sun was doubted by most of Copernicus' contemporaries. It contradicted not only empirical observation, due to the absence of an observable [[stellar parallax]],<ref>[[#Hannam|Hannam]], p. 283</ref> but more significantly at the time, the authority of Aristotle. The discoveries of Kepler and Galileo gave the theory credibility. 

Kepler was an astronomer who is best known for his [[Kepler's laws of planetary motion|laws of planetary motion]], and Kepler´s books ''[[Astronomia nova]]'', ''[[Harmonice Mundi]]'', and ''[[Epitome Astronomiae Copernicanae]]'' influenced among others [[Isaac Newton]], providing one of the foundations for his theory of [[Newton's law of universal gravitation|universal gravitation]].<ref>{{Cite journal|last=Voelkel|first=James R.|date=2001|title=Commentary on Ernan McMullin, "The Impact of Newton's Principia on the Philosophy of Science"|url=https://www.jstor.org/stable/3080920|journal=Philosophy of Science|volume=68|issue=3|pages=319–326|doi=10.1086/392885|jstor=3080920|s2cid=144781947|issn=0031-8248}}</ref> One of the most significant books in the history of astronomy, the Astronomia nova provided strong arguments for heliocentrism and contributed valuable insight into the movement of the planets. This included the first mention of the planets' elliptical paths and the change of their movement to the movement of free floating bodies as opposed to objects on rotating spheres. It is recognized as one of the most important works of the Scientific Revolution.<ref>{{Cite book | last=Voelkel | first=James R. | author-link=James R. Voelkel | title=The composition of Kepler's Astronomia nova | date=2001 | publisher=[[Princeton University Press]] | location=Princeton  | isbn=0-691-00738-1 | pages=1}}</ref> Using the accurate observations of [[Tycho Brahe]], Kepler proposed that the planets move around the Sun not in circular orbits but in elliptical ones. Together with Kepler´s other laws of planetary motion, this allowed him to create a model of the Solar System that was an improvement over Copernicus' original system. 

Galileo's main contributions to the acceptance of the heliocentric system were his mechanics, the observations he made with his telescope, as well as his detailed presentation of the case for the system. Using an early theory of [[inertia]], Galileo could explain why rocks dropped from a tower fall straight down even if the Earth rotates. His observations of the [[moons of Jupiter]], the phases of [[Venus]], the spots on the Sun, and [[List of mountains on the Moon|mountains on the Moon]] all helped to discredit the Aristotelian philosophy and the Ptolemaic theory of the Solar System. Through their combined discoveries, the heliocentric system gained support, and at the end of the 17th century it was generally accepted by astronomers.

This work culminated in the work of Newton, and his ''Principia'' formulated the laws of motion and universal gravitation which dominated scientists' view of the physical universe for the next three centuries. By deriving Kepler's laws of planetary motion from his mathematical description of gravity, and then using the same principles to account for the trajectories of [[comet]]s, the [[tide]]s, the precession of the [[equinox]]es, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the cosmos. This work also demonstrated that the motion of objects on Earth and of celestial bodies could be described by the same principles. His prediction that the Earth should be shaped as an oblate spheroid was later vindicated by other scientists. His laws of motion were to be the solid foundation of mechanics; his [[Newton's law of universal gravitation|law of universal gravitation]] combined terrestrial and celestial mechanics into one great system that seemed to be able to describe the whole world in mathematical formulae.

==== Gravitation ====
[[File:NewtonsPrincipia.jpg|thumb|[[Isaac Newton]]'s ''[[Philosophiæ Naturalis Principia Mathematica|Principia]]'' developed the first set of unified scientific laws.]]

Newton also developed the theory of gravitation. In 1679, Newton began to consider gravitation and its effect on the orbits of planets with reference to Kepler's laws of planetary motion. This followed stimulation by a brief exchange of letters in 1679–80 with Hooke, opened a correspondence intended to elicit contributions from Newton to Royal Society transactions.<ref>''Correspondence of Isaac Newton, vol. 2, 1676–1687'' ed. H.W. Turnbull, Cambridge University Press 1960; at page 297, document No. 235, letter from Hooke to Newton dated 24 November 1679.</ref> Newton's reawakening interest in astronomical matters received further stimulus by the appearance of a comet in the winter of 1680–81, on which he corresponded with [[John Flamsteed]].<ref>[[#Westfall|Westfall]], pp. 391–92</ref> After the exchanges with Hooke, Newton worked out proof that the elliptical form of planetary orbits would result from a [[centripetal force]] [[inverse-square law|inversely proportional to the square of the radius vector]]. Newton communicated his results to [[Edmond Halley]] and to the Royal Society in ''[[De motu corporum in gyrum]]'' in 1684.<ref>Whiteside D.T. (ed.) (1974) ''Mathematical Papers of Isaac Newton'', vol. 6, 1684–1691, Cambridge University Press. p. 30.</ref> This tract contained the nucleus that Newton developed and expanded to form the ''Principia''.<ref>[https://www.bbc.co.uk/history/historic_figures/newton_isaac.shtml Isaac Newton (1643–1727)] {{Webarchive|url=https://web.archive.org/web/20150310093436/http://www.bbc.co.uk/history/historic_figures/newton_isaac.shtml |date=10 March 2015 }}, BBC – History</ref>

The ''Principia'' was published on 5 July 1687 with encouragement and financial help from Halley.<ref>[http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Halley.html Halley biography] {{Webarchive|url=https://web.archive.org/web/20090213164959/http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Halley.html |date=13 February 2009 }}. Groups.dcs.st-and.ac.uk. Retrieved on 26 September 2011.</ref> In this work, Newton states the [[Newton's laws of motion|three universal laws of motion]] that contributed to many advances during the [[Industrial Revolution]] which soon followed and were not to be improved upon for more than 200 years. Many of these advancements continue to be the underpinnings of non-relativistic technologies in the modern world. He used the Latin word ''gravitas'' (weight) for the effect that would become known as [[gravity]] and defined the law of universal gravitation.

Newton's postulate of an invisible [[action at a distance|force able to act over vast distances]] led to him being criticised for introducing "[[occult]] agencies" into science.<ref>Edelglass et al., ''Matter and Mind'', {{ISBN|0-940262-45-2}}. p. 54</ref> Later, in the second edition of the ''Principia'' (1713), Newton firmly rejected such criticisms in a concluding "[[General Scholium]]," writing that it was enough that the phenomena implied a gravitational attraction, as they did; but they did not so far indicate its cause, and it was both unnecessary and improper to frame hypotheses of things that were not implied by the phenomena. (Here Newton used what became his famous expression "''[[hypotheses non fingo]]''").<ref>On the meaning and origins of this expression, see Kirsten Walsh, [https://blogs.otago.ac.nz/emxphi/2010/10/does-newton-feign-an-hypothesis/ Does Newton feign an hypothesis?] {{Webarchive|url=https://web.archive.org/web/20140714120054/https://blogs.otago.ac.nz/emxphi/2010/10/does-newton-feign-an-hypothesis/ |date=14 July 2014 }}, [https://blogs.otago.ac.nz/emxphi/ Early Modern Experimental Philosophy] {{Webarchive|url=https://web.archive.org/web/20110721051523/https://blogs.otago.ac.nz/emxphi/ |date=21 July 2011 }}, 18 October 2010.</ref>