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According to ancient and medieval science, aether (/ˈiːθər/, alternative spellings include æther, aither, and ether), also known as the fifth element or quintessence, is the material that fills the region of the universe beyond the terrestrial sphere.^[1] The concept of aether was used in several theories to explain several natural phenomena, such as the propagation of light and gravity. In the late 19th century, physicists postulated that aether permeated space, providing a medium through which light could travel in a vacuum, but evidence for the presence of such a medium was not found in the Michelson–Morley experiment, and this result has been interpreted to mean that no luminiferous aether exists.^[2]

Mythological origins

The word αἰθήρ (aithḗr) in Homeric Greek means "pure, fresh air" or "clear sky".^[3] In Greek mythology, it was thought to be the pure essence that the gods breathed, filling the space where they lived, analogous to the air breathed by mortals.^[4] It is also personified as a deity, Aether, the son of Erebus and Nyx in traditional Greek mythology.^[5] Aether is related to αἴθω "to incinerate",^[6] and intransitive "to burn, to shine" (related is the name Aithiopes (Ethiopians; see Aethiopia), meaning "people with a burnt (black) visage").^[7]^[8]

Fifth element

Medieval concept of the cosmos. The innermost spheres are the terrestrial spheres, while the outer are made of aether and contain the celestial bodies.

In Plato's Timaeus (58d) speaking about air, Plato mentions that "there is the most translucent kind which is called by the name of aether (αἰθήρ)"^[9] but otherwise he adopted the classical system of four elements. Aristotle, who had been Plato's student at the Academy, agreed on this point with his former mentor, emphasizing additionally that fire has sometimes been mistaken for aether. However, in his Book On the Heavens he introduced a new "first" element to the system of the classical elements of Ionian philosophy. He noted that the four terrestrial classical elements were subject to change and naturally moved linearly. The first element however, located in the celestial regions and heavenly bodies, moved circularly and had none of the qualities the terrestrial classical elements had. It was neither hot nor cold, neither wet nor dry. With this addition the system of elements was extended to five and later commentators started referring to the new first one as the fifth and also called it aether, a word that Aristotle had used in On the Heavens and the Meteorology.^[10]

Aether differed from the four terrestrial elements; it was incapable of motion of quality or motion of quantity. Aether was only capable of local motion. Aether naturally moved in circles, and had no contrary, or unnatural, motion. Aristotle also stated that celestial spheres made of aether held the stars and planets. The idea of aethereal spheres moving with natural circular motion led to Aristotle's explanation of the observed orbits of stars and planets in perfectly circular motion.^[1]^[11]

Medieval scholastic philosophers granted aether changes of density, in which the bodies of the planets were considered to be more dense than the medium which filled the rest of the universe.^[12] Robert Fludd stated that the aether was "subtler than light". Fludd cites the 3rd-century view of Plotinus, concerning the aether as penetrative and non-material.^[13]

Quintessence

Quintessence (𝓠) is the Latinate name of the fifth element used by medieval alchemists for a medium similar or identical to that thought to make up the heavenly bodies. It was noted that there was very little presence of quintessence within the terrestrial sphere. Due to the low presence of quintessence, earth could be affected by what takes place within the heavenly bodies.^[15] This theory was developed in the 14th century text The testament of Lullius, attributed to Ramon Llull.^{[citation needed]} The use of quintessence became popular within medieval alchemy. Quintessence stemmed from the medieval elemental system, which consisted of the four classical elements, and aether, or quintessence, in addition to two chemical elements representing metals: sulphur, "the stone which burns", which characterized the principle of combustibility, and mercury, which contained the idealized principle of metallic properties.

This elemental system spread rapidly throughout all of Europe and became popular with alchemists, especially in medicinal alchemy. Medicinal alchemy then sought to isolate quintessence and incorporate it within medicine and elixirs.^[15] Due to quintessence's pure and heavenly quality, it was thought that through consumption one may rid oneself of any impurities or illnesses. In The book of Quintessence, a 15th-century English translation of a continental text, quintessence was used as a medicine for many of man's illnesses. A process given for the creation of quintessence is distillation of alcohol seven times.^[16] Over the years, the term quintessence has become synonymous with elixirs, medicinal alchemy, and the philosopher's stone itself.^[17]

Legacy

With the 18th century physics developments, physical models known as "aether theories" made use of a similar concept for the explanation of the propagation of electromagnetic and gravitational forces. As early as the 1670s, Newton used the idea of aether to help match observations to strict mechanical rules of his physics.^[18]^[a] The early modern aether had little in common with the aether of classical elements from which the name was borrowed. These aether theories are considered to be scientifically obsolete, as the development of special relativity showed that Maxwell's equations do not require the aether for the transmission of these forces. Einstein noted that his own model which replaced these theories could itself be thought of as an aether, as it implied that the empty space between objects had its own physical properties.^[20]

Despite the early modern aether models being superseded by general relativity, occasionally some physicists have attempted to reintroduce the concept of aether in an attempt to address perceived deficiencies in current physical models.^[21] One proposed model of dark energy has been named "quintessence" by its proponents, in honor of the classical element.^[22] This idea relates to the hypothetical form of dark energy postulated as an explanation of observations of an accelerating universe. It has also been called a fifth fundamental force.

Aether and light

The motion of light was a long-standing investigation in physics for hundreds of years before the 20th century. The use of aether to describe this motion was popular during the 17th and 18th centuries, including a theory proposed by Johann II Bernoulli, who was recognized in 1736 with the prize of the French Academy. In his theory, all space is permeated by aether containing "excessively small whirlpools". These whirlpools allow for aether to have a certain elasticity, transmitting vibrations from the corpuscular packets of light as they travel through.^[23]

This theory of luminiferous aether would influence the wave theory of light proposed by Christiaan Huygens, in which light traveled in the form of longitudinal waves via an "omnipresent, perfectly elastic medium having zero density, called aether". At the time, it was thought that in order for light to travel through a vacuum, there must have been a medium filling the void through which it could propagate, as sound through air or ripples in a pool. Later, when it was proved that the nature of light wave is transverse instead of longitudinal, Huygens' theory was replaced by subsequent theories proposed by Maxwell, Einstein and de Broglie, which rejected the existence and necessity of aether to explain the various optical phenomena. These theories were supported by the results of the Michelson–Morley experiment in which evidence for the motion of aether was conclusively absent.^[24] The results of the experiment influenced many physicists of the time and contributed to the eventual development of Einstein's theory of special relativity.^[25]

Aether and gravitation

In 1682, Jakob Bernoulli formulated the theory that the hardness of the bodies depended on the pressure of the aether.^[26] Aether has been used in various gravitational theories as a medium to help explain gravitation and what causes it.

A few years later, aether was used in one of Sir Isaac Newton's first published theories of gravitation, Philosophiæ Naturalis Principia Mathematica (the Principia, 1687). He based the whole description of planetary motions on a theoretical law of dynamic interactions. He renounced standing attempts at accounting for this particular form of interaction between distant bodies by introducing a mechanism of propagation through an intervening medium.^[27] He calls this intervening medium aether. In his aether model, Newton describes aether as a medium that "flows" continually downward toward the Earth's surface and is partially absorbed and partially diffused. This "circulation" of aether is what he associated the force of gravity with to help explain the action of gravity in a non-mechanical fashion.^[27] This theory described different aether densities, creating an aether density gradient. His theory also explains that aether was dense within objects and rare without them. As particles of denser aether interacted with the rare aether they were attracted back to the dense aether much like cooling vapors of water are attracted back to each other to form water.^[28] In the Principia he attempts to explain the elasticity and movement of aether by relating aether to his static model of fluids. This elastic interaction is what caused the pull of gravity to take place, according to this early theory, and allowed an explanation for action at a distance instead of action through direct contact. Newton also explained this changing rarity and density of aether in his letter to Robert Boyle in 1679.^[28] He illustrated aether and its field around objects in this letter as well and used this as a way to inform Robert Boyle about his theory.^[29] Although Newton eventually changed his theory of gravitation to one involving force and the laws of motion, his starting point for the modern understanding and explanation of gravity came from his original aether model on gravitation.^[30]^{[self-published source?]}

References

Footnotes

^ In a 1675 paper, he also wrote a number of pages speculating that aether may explain how the soul interacts with the body.^[19]

Citations

^ ^a ^b Lloyd, G. E. R. (1968), Aristotle: The Growth and Structure of his Thought, Cambridge: Cambridge Univ. Pr., pp. 133–139, ISBN 0-521-09456-9, Believing that the movements of the heavenly bodies are continuous, natural and circular, and that the natural movements of the four terrestrial elements are rectilinear and discontinuous, Aristotle concluded that the heavenly bodies must be composed of a fifth element, aither [sic].
^ Carl S. Helrich, The Classical Theory of Fields: Electromagnetism Berlin, Springer 2012, p. 26.
^ Hobart, Michael E. (2018-04-16). The Great Rift: Literacy, Numeracy, and the Religion-Science Divide. Harvard University Press. ISBN 978-0-674-98516-2.
^ Allison Muri, The Enlightenment Cyborg: A History of Communications and Control in the Human Machine, 1660-1830, p. 63, University of Toronto Press, 2007 ISBN 0802088503.
^ "AITHER". AETHER : Greek protogenos god of upper air & light; mythology : AITHER. Retrieved January 16, 2016.
^ Pokorny, Julius (1959). Indogermanisches etymologisches Wörterbuch, s.v. ai-dh-.
^ Αἰθίοψ in Liddell, Scott, A Greek–English Lexicon: "Αἰθίοψ, οπος, ὁ, fem. Αἰθιοπίς, ίδος, ἡ (Αἰθίοψ as fem., A.Fr.328, 329): pl. 'Αἰθιοπῆες' Il.1.423, whence nom. 'Αἰθιοπεύς' Call.Del.208: (αἴθω, ὄψ):— properly, Burnt-face, i.e. Ethiopian, negro, Hom., etc.; prov., Αἰθίοπα σμήχειν 'to wash a blackamoor white', Luc.Ind. 28." Cf. Etymologicum Genuinum s.v. Αἰθίοψ, Etymologicum Gudianum s.v.v. Αἰθίοψ. "Αἰθίοψ". Etymologicum Magnum (in Greek). Leipzig: Lipsiae Apud J.A.G. Weigel. 1818.
^ Fage, John (2013-10-23). A History of Africa. Routledge. pp. 25–26. ISBN 9781317797272. Retrieved 20 January 2015. ...[Africa's Indian Ocean] coast was called Azania, and no 'Ethiopeans', dark skinned people, were mentioned amongst its inhabitants.
^ Plato, Timaeus 58d.
^ Hahm, David E. (1982). "The fifth element in Aristotle's De Philosophia: A Critical Re-Examination". The Journal of Hellenic Studies. 102: 60–74, at p.62. doi:10.2307/631126. JSTOR 631126. S2CID 170926485.
^ George Smoot III. "Aristotle's Physics". lbl.gov. Archived from the original on 20 December 2016. Retrieved 20 December 2016.
^ Grant, Edward (1996). Planets, Stars, & Orbs: The Medieval Cosmos, 1200-1687 (1st pbk. ed.). Cambridge [England]: Cambridge University Press. pp. 322–428. ISBN 978-0-521-56509-7.
^ Robert Fludd, "Mosaical Philosophy". London, Humphrey Moseley, 1659, p. 221.
^ B.J.T. Dobbs (1983) The Foundations of Newton's Alchemy, p. xiv.
^ ^a ^b The Alchemists, F. Sherwood Taylor, page 95.
^ The book of Quintessence Archived 2015-09-24 at the Wayback Machine, Early English Text Society original series number 16, edited by F. J. Furnivall.
^ The Dictionary of Alchemy, Mark Haeffner.
^ Margaret Osler, Reconfiguring the World. The Johns Hopkins University Press 2010. (155).
^ Gillispie, Charles Coulston (1960). The Edge of Objectivity: An Essay in the History of Scientific Ideas. Princeton, NJ: Princeton University Press. pp. 129–30. ISBN 0-691-02350-6.
^ Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922)
^ Dirac, Paul (1951). "Is there an Aether?". Nature. 168 (4282): 906–907. Bibcode:1951Natur.168..906D. doi:10.1038/168906a0. S2CID 4288946.
^ Zlatev, I.; Wang, L.; Steinhardt, P. (1999). "Quintessence, Cosmic Coincidence, and the Cosmological Constant". Physical Review Letters (Submitted manuscript). 82 (5): 896–899. arXiv:astro-ph/9807002. Bibcode:1999PhRvL..82..896Z. doi:10.1103/PhysRevLett.82.896. S2CID 119073006.
^ Whittaker, Edmund Taylor, A History of the Theories of Aether and Electricity from the Age of Descartes to the Close of the 19th Century (1910), pp. 101-02.
^ Michelson, Albert A. (1881). "The Relative Motion of the Earth and the Luminiferous Ether". American Journal of Science. 22 (128): 120–129. Bibcode:1881AmJS...22..120M. doi:10.2475/ajs.s3-22.128.120. S2CID 130423116.
^ Shankland, R. S. (1964). "Michelson-Morley Experiment". American Journal of Physics. 32 (1): 16. Bibcode:1964AmJPh..32...16S. doi:10.1119/1.1970063.
^ "Bernoulli nell'Enciclopedia Treccani".
^ ^a ^b Rosenfeld, L. (1969). "Newton's views on aether and gravitation". Archive for History of Exact Sciences. 6 (1): 29–37. doi:10.1007/BF00327261. S2CID 122494617.
^ ^a ^b Newton, Isaac."Isaac Newton to Robert Boyle, 1679." 28 February 1679.
^ James DeMeo (2009). "Isaac Newton's Letter to Robert Boyle, on the Cosmic Ether of Space - 1679". orgonelab.org. Archived from the original on 20 December 2016. Retrieved 20 December 2016.
^ Andrew Robishaw (9 April 2015). The Esoteric Codex: Esoteric Cosmology. Lulu.com. p. 6. ISBN 9781329053083. Retrieved 20 December 2016.^{[self-published source]}

[20] In a 1675 paper, he also wrote a number of pages speculating that aether may explain how the soul interacts with the body.^[19]

[Lloyd-1] Lloyd, G. E. R. (1968), Aristotle: The Growth and Structure of his Thought, Cambridge: Cambridge Univ. Pr., pp. 133–139, ISBN 0-521-09456-9, Believing that the movements of the heavenly bodies are continuous, natural and circular, and that the natural movements of the four terrestrial elements are rectilinear and discontinuous, Aristotle concluded that the heavenly bodies must be composed of a fifth element, aither [sic].

[2] Carl S. Helrich, The Classical Theory of Fields: Electromagnetism Berlin, Springer 2012, p. 26.

[3] Hobart, Michael E. (2018-04-16). The Great Rift: Literacy, Numeracy, and the Religion-Science Divide. Harvard University Press. ISBN 978-0-674-98516-2.

[4] Allison Muri, The Enlightenment Cyborg: A History of Communications and Control in the Human Machine, 1660-1830, p. 63, University of Toronto Press, 2007 ISBN 0802088503.

[5] "AITHER". AETHER : Greek protogenos god of upper air & light; mythology : AITHER. Retrieved January 16, 2016.

[6] Pokorny, Julius (1959). Indogermanisches etymologisches Wörterbuch, s.v. ai-dh-.

[7] Αἰθίοψ in Liddell, Scott, A Greek–English Lexicon: "Αἰθίοψ, οπος, ὁ, fem. Αἰθιοπίς, ίδος, ἡ (Αἰθίοψ as fem., A.Fr.328, 329): pl. 'Αἰθιοπῆες' Il.1.423, whence nom. 'Αἰθιοπεύς' Call.Del.208: (αἴθω, ὄψ):— properly, Burnt-face, i.e. Ethiopian, negro, Hom., etc.; prov., Αἰθίοπα σμήχειν 'to wash a blackamoor white', Luc.Ind. 28." Cf. Etymologicum Genuinum s.v. Αἰθίοψ, Etymologicum Gudianum s.v.v. Αἰθίοψ. "Αἰθίοψ". Etymologicum Magnum (in Greek). Leipzig: Lipsiae Apud J.A.G. Weigel. 1818.

[Fage2526-8] Fage, John (2013-10-23). A History of Africa. Routledge. pp. 25–26. ISBN 9781317797272. Retrieved 20 January 2015. ...[Africa's Indian Ocean] coast was called Azania, and no 'Ethiopeans', dark skinned people, were mentioned amongst its inhabitants.

[9] Plato, Timaeus 58d.

[10] Hahm, David E. (1982). "The fifth element in Aristotle's De Philosophia: A Critical Re-Examination". The Journal of Hellenic Studies. 102: 60–74, at p.62. doi:10.2307/631126. JSTOR 631126. S2CID 170926485.

[smoot-11] George Smoot III. "Aristotle's Physics". lbl.gov. Archived from the original on 20 December 2016. Retrieved 20 December 2016.

[12] Grant, Edward (1996). Planets, Stars, & Orbs: The Medieval Cosmos, 1200-1687 (1st pbk. ed.). Cambridge [England]: Cambridge University Press. pp. 322–428. ISBN 978-0-521-56509-7.

[13] Robert Fludd, "Mosaical Philosophy". London, Humphrey Moseley, 1659, p. 221.

[14] B.J.T. Dobbs (1983) The Foundations of Newton's Alchemy, p. xiv.

[TheAlchemists-15] The Alchemists, F. Sherwood Taylor, page 95.

[16] The book of Quintessence Archived 2015-09-24 at the Wayback Machine, Early English Text Society original series number 16, edited by F. J. Furnivall.

[17] The Dictionary of Alchemy, Mark Haeffner.

[18] Margaret Osler, Reconfiguring the World. The Johns Hopkins University Press 2010. (155).

[19] Gillispie, Charles Coulston (1960). The Edge of Objectivity: An Essay in the History of Scientific Ideas. Princeton, NJ: Princeton University Press. pp. 129–30. ISBN 0-691-02350-6.

[21] Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922)

[22] Dirac, Paul (1951). "Is there an Aether?". Nature. 168 (4282): 906–907. Bibcode:1951Natur.168..906D. doi:10.1038/168906a0. S2CID 4288946.

[23] Zlatev, I.; Wang, L.; Steinhardt, P. (1999). "Quintessence, Cosmic Coincidence, and the Cosmological Constant". Physical Review Letters (Submitted manuscript). 82 (5): 896–899. arXiv:astro-ph/9807002. Bibcode:1999PhRvL..82..896Z. doi:10.1103/PhysRevLett.82.896. S2CID 119073006.

[24] Whittaker, Edmund Taylor, A History of the Theories of Aether and Electricity from the Age of Descartes to the Close of the 19th Century (1910), pp. 101-02.

[25] Michelson, Albert A. (1881). "The Relative Motion of the Earth and the Luminiferous Ether". American Journal of Science. 22 (128): 120–129. Bibcode:1881AmJS...22..120M. doi:10.2475/ajs.s3-22.128.120. S2CID 130423116.

[26] Shankland, R. S. (1964). "Michelson-Morley Experiment". American Journal of Physics. 32 (1): 16. Bibcode:1964AmJPh..32...16S. doi:10.1119/1.1970063.

[27] "Bernoulli nell'Enciclopedia Treccani".

[Rosenfeld1969-28] Rosenfeld, L. (1969). "Newton's views on aether and gravitation". Archive for History of Exact Sciences. 6 (1): 29–37. doi:10.1007/BF00327261. S2CID 122494617.

[newton1679-29] Newton, Isaac."Isaac Newton to Robert Boyle, 1679." 28 February 1679.

[letter-30] James DeMeo (2009). "Isaac Newton's Letter to Robert Boyle, on the Cosmic Ether of Space - 1679". orgonelab.org. Archived from the original on 20 December 2016. Retrieved 20 December 2016.

[robishaw-31] Andrew Robishaw (9 April 2015). The Esoteric Codex: Esoteric Cosmology. Lulu.com. p. 6. ISBN 9781329053083. Retrieved 20 December 2016.^{[self-published source]}

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@@ Line 1: / Line 1: @@
 {{short description|Classical element}}
 {{classic element}}
-According to ancient and [[History of science in the Middle Ages|medieval science]], '''aether''' ({{IPAc-en|ˈ|iː|θ|ər}}, alternative spellings include ''æther'', ''aither'', and ''ether''), also known as the '''fifth element''' or '''quintessence''', is the material that fills the region of the [[universe]]  beyond the [[Sublunary sphere|terrestrial sphere]].<ref name="Lloyd" /> The concept of aether was used in several theories to explain several natural phenomena, such as the traveling of light and gravity. In the late 19th century, physicists postulated that aether permeated all throughout space, providing a medium through which light could travel in a [[vacuum]], but evidence for the presence of such a medium was not found in the [[Michelson–Morley experiment]], and this result has been interpreted as meaning that no such [[luminiferous aether]] exists.<ref>Carl S. Helrich,  [https://books.google.com/books?id=aRpJJXc-LCIC&pg=PA26 ''The Classical Theory of Fields: Electromagnetism''] Berlin, Springer 2012, p. 26.</ref>
+According to ancient and [[History of science in the Middle Ages|medieval science]], '''aether''' ({{IPAc-en|ˈ|iː|θ|ər}}, alternative spellings include ''æther'', ''aither'', and ''ether''), also known as the '''fifth element''' or '''quintessence''', is the material that fills the region of the [[universe]] beyond the [[Sublunary sphere|terrestrial sphere]].<ref name="Lloyd" /> The concept of aether was used in several theories to explain several natural phenomena, such as the propagation of light and gravity. In the late 19th century, physicists postulated that aether permeated space, providing a medium through which light could travel in a [[vacuum]], but evidence for the presence of such a medium was not found in the [[Michelson–Morley experiment]], and this result has been interpreted to mean that no [[luminiferous aether]] exists.<ref>Carl S. Helrich,  [https://books.google.com/books?id=aRpJJXc-LCIC&pg=PA26 ''The Classical Theory of Fields: Electromagnetism''] Berlin, Springer 2012, p. 26.</ref>
 ==Mythological origins==
 {{main|Aether (mythology)}}
 {{see also|Empyrean}}
-The word  {{lang|grc|αἰθήρ}} (''aithḗr'') in [[Homeric Greek]] means "pure, fresh air" or "clear sky".<ref>{{Cite book |last=Hobart |first=Michael E. |url=https://books.google.com/books?id=r7pTDwAAQBAJ&dq=aether+homeric+greek+pure+sky&pg=PT266 |title=The Great Rift: Literacy, Numeracy, and the Religion-Science Divide |date=2018-04-16 |publisher=Harvard University Press |isbn=978-0-674-98516-2 |language=en}}</ref> In [[Greek mythology]], it was thought to be the pure essence that the gods breathed, filling the space where they lived, analogous to the ''[[Air (classical element)|air]]'' breathed by mortals.<ref>Allison Muri, ''The Enlightenment Cyborg: A History of Communications and Control in the Human Machine, 1660-1830'', p. 63, University of Toronto Press, 2007 {{ISBN|0802088503}}.</ref> It is also personified as a deity, [[Aether (mythology)|Aether]], the son of [[Erebus]] and [[Nyx (mythology)|Nyx]] in traditional Greek mythology.<ref>{{Cite web|url = http://www.theoi.com/Protogenos/Aither.html|title = AITHER|access-date = January 16, 2016|website = AETHER : Greek protogenos god of upper air & light ; mythology : AITHER}}</ref> Aether is related to {{lang|grc|αἴθω}} "to incinerate",<ref>[[Julius Pokorny|Pokorny, Julius]] (1959). [[Indogermanisches etymologisches Wörterbuch]], s.v. ''ai-dh-.''</ref> and intransitive "to burn, to shine" (related is the name ''Aithiopes'' ([[Ethiopia]]ns; see [[Aethiopia]]), meaning "people with a burnt (black) visage").<ref>[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D*ai%29qi%2Foy Αἰθίοψ] in Liddell, Scott, ''[[A Greek–English Lexicon]]'': "Αἰθίοψ , οπος, ὁ, fem. Αἰθιοπίς , ίδος, ἡ (Αἰθίοψ as fem., A.Fr.328, 329): pl. 'Αἰθιοπῆες' Il.1.423, whence nom. 'Αἰθιοπεύς' Call.Del.208: (αἴθω, ὄψ):— properly, Burnt-face, i.e. Ethiopian, negro, Hom., etc.; prov., Αἰθίοπα σμήχειν 'to wash a blackamoor white', Luc.Ind. 28." Cf. ''[[Etymologicum Genuinum]]'' s.v. {{lang|grc|Αἰθίοψ}}, ''Etymologicum Gudianum'' s.v.v. {{lang|grc|Αἰθίοψ}}. {{cite book|title=Etymologicum Magnum|language=el|chapter=Αἰθίοψ|chapter-url=https://archive.org/stream/etymologikontome00etymuoft#page/n34/mode/1up|place=Leipzig|year=1818|publisher=Lipsiae Apud J.A.G. Weigel}}</ref><ref name="Fage2526">{{cite book|last1=Fage|first1=John|title=A History of Africa|publisher=Routledge|isbn=9781317797272|pages=25–26|url=https://books.google.com/books?id=mXa4AQAAQBAJ|access-date=20 January 2015|quote=...[Africa's Indian Ocean] coast was called Azania, and no 'Ethiopeans', dark skinned people, were mentioned amongst its inhabitants.|date=2013-10-23}}</ref>
+The word {{lang|grc|αἰθήρ}} (''aithḗr'') in [[Homeric Greek]] means "pure, fresh air" or "clear sky".<ref>{{Cite book |last=Hobart |first=Michael E. |url=https://books.google.com/books?id=r7pTDwAAQBAJ&dq=aether+homeric+greek+pure+sky&pg=PT266 |title=The Great Rift: Literacy, Numeracy, and the Religion-Science Divide |date=2018-04-16 |publisher=Harvard University Press |isbn=978-0-674-98516-2 |language=en}}</ref> In [[Greek mythology]], it was thought to be the pure essence that the gods breathed, filling the space where they lived, analogous to the ''[[Air (classical element)|air]]'' breathed by mortals.<ref>Allison Muri, ''The Enlightenment Cyborg: A History of Communications and Control in the Human Machine, 1660-1830'', p. 63, University of Toronto Press, 2007 {{ISBN|0802088503}}.</ref> It is also personified as a deity, [[Aether (mythology)|Aether]], the son of [[Erebus]] and [[Nyx (mythology)|Nyx]] in traditional Greek mythology.<ref>{{Cite web |url=http://www.theoi.com/Protogenos/Aither.html |title=AITHER |access-date=January 16, 2016 |website=AETHER : Greek protogenos god of upper air & light; mythology : AITHER}}</ref> Aether is related to {{lang|grc|αἴθω}} "to incinerate",<ref>[[Julius Pokorny|Pokorny, Julius]] (1959). [[Indogermanisches etymologisches Wörterbuch]], s.v. ''ai-dh-.''</ref> and intransitive "to burn, to shine" (related is the name ''Aithiopes'' ([[Ethiopia]]ns; see [[Aethiopia]]), meaning "people with a burnt (black) visage").<ref>[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D*ai%29qi%2Foy Αἰθίοψ] in Liddell, Scott, ''[[A Greek–English Lexicon]]'': "Αἰθίοψ, οπος, ὁ, fem. Αἰθιοπίς, ίδος, ἡ (Αἰθίοψ as fem., A.Fr.328, 329): pl. 'Αἰθιοπῆες' Il.1.423, whence nom. 'Αἰθιοπεύς' Call.Del.208: (αἴθω, ὄψ):— properly, Burnt-face, i.e. Ethiopian, negro, Hom., etc.; prov., Αἰθίοπα σμήχειν 'to wash a blackamoor white', Luc.Ind. 28." Cf. ''[[Etymologicum Genuinum]]'' s.v. {{lang|grc|Αἰθίοψ}}, ''Etymologicum Gudianum'' s.v.v. {{lang|grc|Αἰθίοψ}}. {{cite book |title=Etymologicum Magnum |language=el |chapter=Αἰθίοψ |chapter-url=https://archive.org/stream/etymologikontome00etymuoft#page/n34/mode/1up |place=Leipzig |year=1818 |publisher=Lipsiae Apud J.A.G. Weigel}}</ref><ref name="Fage2526">{{cite book |last1=Fage |first1=John |title=A History of Africa |publisher=Routledge |isbn=9781317797272 |pages=25–26 |url=https://books.google.com/books?id=mXa4AQAAQBAJ |access-date=20 January 2015|quote=...[Africa's Indian Ocean] coast was called Azania, and no 'Ethiopeans', dark skinned people, were mentioned amongst its inhabitants.|date=2013-10-23}}</ref>
 ==Fifth element==<!-- This section is linked from [[Classical element]] -->
 [[File:Ptolemaicsystem-small.png|thumb|Medieval concept of the cosmos. The innermost spheres are the terrestrial spheres, while the outer are made of aether and contain the celestial bodies.]]
-In [[Plato]]'s ''[[Timaeus (dialogue)|Timaeus]]'' (58d) speaking about air, Plato mentions that "there is the most translucent kind which is called by the name of aether (αἰθήρ)"<ref>[[Plato]],  ''[[Timaeus (dialogue)|Timaeus]]'' [https://www.perseus.tufts.edu/hopper/text;jsessionid=1C8F72843B9D65CB4C634D700A6E694C?doc=Plat.+Tim.+58d 58d].</ref> but otherwise he adopted the classical system of four elements. [[Aristotle]], who had been Plato's student at the [[Akademia|Academy]], agreed on this point with his former mentor, emphasizing additionally that fire has sometimes been mistaken for aether. However, in his Book ''[[On the Heavens]]'' he introduced a new "first" element to the system of the [[classical element]]s of [[Ionian School (philosophy)|Ionian]] [[Greek philosophy|philosophy]]. He noted that the four terrestrial classical elements were subject to change and naturally moved linearly. The first element however, located in the celestial regions and heavenly bodies, moved circularly and had none of the qualities the terrestrial classical elements had. It was neither hot nor cold, neither wet nor dry. With this addition the system of elements was extended to five and later commentators started referring to the new first one as the fifth and also called it ''aether'', a word that Aristotle had not used.<ref>{{cite journal |last1=Hahm |first1=David E. |title=The fifth element in Aristotle's ''De Philosophia'': A Critical Re-Examination |journal=The Journal of Hellenic Studies |date=1982 |volume=102 |pages=60–74 |doi=10.2307/631126|jstor=631126 |s2cid=170926485 }}</ref>
+In [[Plato]]'s ''[[Timaeus (dialogue)|Timaeus]]'' (58d) speaking about air, Plato mentions that "there is the most translucent kind which is called by the name of aether (αἰθήρ)"<ref>[[Plato]],  ''[[Timaeus (dialogue)|Timaeus]]'' [https://www.perseus.tufts.edu/hopper/text;jsessionid=1C8F72843B9D65CB4C634D700A6E694C?doc=Plat.+Tim.+58d 58d].</ref> but otherwise he adopted the classical system of four elements. [[Aristotle]], who had been Plato's student at the [[Akademia|Academy]], agreed on this point with his former mentor, emphasizing additionally that fire has sometimes been mistaken for aether. However, in his Book ''[[On the Heavens]]'' he introduced a new "first" element to the system of the [[classical element]]s of [[Ionian School (philosophy)|Ionian]] [[Greek philosophy|philosophy]]. He noted that the four terrestrial classical elements were subject to change and naturally moved linearly. The first element however, located in the celestial regions and heavenly bodies, moved circularly and had none of the qualities the terrestrial classical elements had. It was neither hot nor cold, neither wet nor dry. With this addition the system of elements was extended to five and later commentators started referring to the new first one as the fifth and also called it ''aether'', a word that Aristotle had used in ''On the Heavens'' and the ''Meteorology''.<ref>{{cite journal |last1=Hahm |first1=David E. |title=The fifth element in Aristotle's ''De Philosophia'': A Critical Re-Examination |journal=The Journal of Hellenic Studies |date=1982 |volume=102 |pages=60–74, at p.62 |doi=10.2307/631126|jstor=631126 |s2cid=170926485 }}</ref>
-Aether differed from the four terrestrial elements; it was incapable of motion of quality or motion of quantity. Aether was only capable of local motion. Aether naturally moved in circles, and had no contrary, or unnatural, motion. Aristotle also noted that [[celestial spheres]] made of aether held the stars and planets. The idea of aethereal spheres moving with natural circular motion led to Aristotle's explanation of the observed orbits of stars and planets in perfectly circular motion.<ref name = "Lloyd">{{ Citation | last = Lloyd | first = G. E. R. | author-link = G. E. R. Lloyd | date = 1968 | title = Aristotle: The Growth and Structure of his Thought | publisher = Cambridge Univ. Pr. | place = Cambridge | pages = 133–139 | isbn = 0-521-09456-9 | quote = Believing that the movements of the heavenly bodies are continuous, natural and circular, and that the natural movements of the four terrestrial elements are rectilinear and discontinuous, Aristotle concluded that the heavenly bodies must be composed of a fifth element, aither [sic].}}</ref><ref name="smoot">{{cite web|url=http://aether.lbl.gov/www/classes/p10/aristotle-physics.html |title=Aristotle's Physics |author=George Smoot III |website=lbl.gov |access-date=20 December 2016 |archive-url=https://web.archive.org/web/20161220230803/http://aether.lbl.gov/www/classes/p10/aristotle-physics.html |archive-date=20 December 2016 |url-status=live }}</ref>
+Aether differed from the four terrestrial elements; it was incapable of motion of quality or motion of quantity. Aether was only capable of local motion. Aether naturally moved in circles, and had no contrary, or unnatural, motion. Aristotle also stated that [[celestial spheres]] made of aether held the stars and planets. The idea of aethereal spheres moving with natural circular motion led to Aristotle's explanation of the observed orbits of stars and planets in perfectly circular motion.<ref name = "Lloyd">{{Citation |last=Lloyd |first=G. E. R. |author-link=G. E. R. Lloyd |date=1968 |title=Aristotle: The Growth and Structure of his Thought |publisher=Cambridge Univ. Pr. |place=Cambridge |pages=133–139 |isbn=0-521-09456-9 |quote=Believing that the movements of the heavenly bodies are continuous, natural and circular, and that the natural movements of the four terrestrial elements are rectilinear and discontinuous, Aristotle concluded that the heavenly bodies must be composed of a fifth element, aither [sic].}}</ref><ref name="smoot">{{cite web |url=http://aether.lbl.gov/www/classes/p10/aristotle-physics.html |title=Aristotle's Physics |author=George Smoot III |website=lbl.gov |access-date=20 December 2016 |archive-url=https://web.archive.org/web/20161220230803/http://aether.lbl.gov/www/classes/p10/aristotle-physics.html |archive-date=20 December 2016 |url-status=live }}</ref>
-Medieval scholastic philosophers granted ''aether'' changes of density, in which the bodies of the planets were considered to be more dense than the medium which filled the rest of the universe.<ref>{{cite book|last1=Grant|first1=Edward|title=Planets, Stars, & Orbs: The Medieval Cosmos, 1200-1687|date=1996|publisher=Cambridge University Press|location=Cambridge [England]|isbn=978-0-521-56509-7|pages=322–428|edition=1st pbk.}}</ref> [[Robert Fludd]] stated that the aether was "subtler than light". Fludd cites the 3rd-century view of [[Plotinus]], concerning the aether as penetrative and non-material.<ref>Robert Fludd, "Mosaical Philosophy". London, Humphrey Moseley, 1659, p. 221.</ref>
+Medieval scholastic philosophers granted ''aether'' changes of density, in which the bodies of the planets were considered to be more dense than the medium which filled the rest of the universe.<ref>{{cite book |last1=Grant |first1=Edward |title=Planets, Stars, & Orbs: The Medieval Cosmos, 1200-1687 |date=1996 |publisher=Cambridge University Press |location=Cambridge [England] |isbn=978-0-521-56509-7 |pages=322–428 |edition=1st pbk.}}</ref> [[Robert Fludd]] stated that the aether was "subtler than light". Fludd cites the 3rd-century view of [[Plotinus]], concerning the aether as penetrative and non-material.<ref>Robert Fludd, "Mosaical Philosophy". London, Humphrey Moseley, 1659, p. 221.</ref>
 ==Quintessence==
@@ Line 20: / Line 20: @@
 [[File:Bismuth trident symbol.svg|thumb|upright=0.5|A symbol for quintessence in the works of [[Isaac Newton]]. Also abbreviated {{angbr|q̄}} and {{angbr|ē}}.<ref>B.J.T. Dobbs (1983) ''The Foundations of Newton's Alchemy'', p. xiv.</ref>]]
 [[File:Aether symbol.svg|thumb|upright=0.5|The symbol for aether in the works of [[Torbern Bergman]] (ca. 1775)]]
-Quintessence (𝓠) is the [[Latinate]] name of the fifth element used by medieval alchemists for a medium similar or identical to that thought to make up the heavenly bodies. It was noted that there was very little presence of quintessence within the terrestrial sphere. Due to the low presence of quintessence, earth could be affected by what takes place within the heavenly bodies.<ref name="TheAlchemists">''The Alchemists'', F. Sherwood Taylor, page 95.</ref> This theory was developed in the 14th century text ''The testament of Lullius'', attributed to [[Ramon Llull]].{{cn|date=December 2020}} The use of quintessence became popular within medieval alchemy. Quintessence stemmed from the medieval elemental system, which consisted of the four classical elements, and aether, or quintessence, in addition to two chemical elements representing metals: [[sulphur]], "the stone which burns", which characterized the principle of combustibility, and [[mercury (element)|mercury]], which contained the idealized principle of metallic properties.
+Quintessence (𝓠) is the [[Latinate]] name of the fifth element used by medieval alchemists for a medium similar or identical to that thought to make up the heavenly bodies. It was noted that there was very little presence of quintessence within the terrestrial sphere. Due to the low presence of quintessence, earth could be affected by what takes place within the heavenly bodies.<ref name="TheAlchemists">''The Alchemists'', F. Sherwood Taylor, page 95.</ref> This theory was developed in the 14th century text ''The testament of Lullius'', attributed to [[Ramon Llull]].{{citation needed|date=December 2020}} The use of quintessence became popular within medieval alchemy. Quintessence stemmed from the medieval elemental system, which consisted of the four classical elements, and aether, or quintessence, in addition to two chemical elements representing metals: [[sulphur]], "the stone which burns", which characterized the principle of combustibility, and [[mercury (element)|mercury]], which contained the idealized principle of metallic properties.
-This elemental system spread rapidly throughout all of Europe and became popular with alchemists, especially in medicinal alchemy. Medicinal alchemy then sought to isolate quintessence and incorporate it within medicine and elixirs.<ref name="TheAlchemists" /> Due to quintessence's pure and heavenly quality, it was thought that through consumption one may rid oneself of any impurities or illnesses. In ''The book of Quintessence'', a 15th-century English translation of a continental text, quintessence was used as a medicine for many of man's illnesses. A process given for the creation of quintessence is [[distillation]] of alcohol seven times.<ref>[http://www.stavacademy.co.uk/mimir/quintessence.htm ''The book of Quintessence''] {{Webarchive|url=https://web.archive.org/web/20150924110119/http://www.stavacademy.co.uk/mimir/quintessence.htm|date=2015-09-24}}, Early English Text Society original series number 16, edited by F. J. Furnivall.</ref> Over the years, the term quintessence has become synonymous with [[elixirs]], medicinal [[alchemy]], and the [[philosopher's stone]] itself.<ref>''The Dictionary of Alchemy'', Mark Haeffner.</ref>
+This elemental system spread rapidly throughout all of Europe and became popular with alchemists, especially in medicinal alchemy. Medicinal alchemy then sought to isolate quintessence and incorporate it within medicine and elixirs.<ref name="TheAlchemists" /> Due to quintessence's pure and heavenly quality, it was thought that through consumption one may rid oneself of any impurities or illnesses. In ''The book of Quintessence'', a 15th-century English translation of a continental text, quintessence was used as a medicine for many of man's illnesses. A process given for the creation of quintessence is [[distillation]] of alcohol seven times.<ref>[http://www.stavacademy.co.uk/mimir/quintessence.htm ''The book of Quintessence''] {{Webarchive|url=https://web.archive.org/web/20150924110119/http://www.stavacademy.co.uk/mimir/quintessence.htm|date=2015-09-24}}, Early English Text Society original series number 16, edited by F. J. Furnivall.</ref> Over the years, the term quintessence has become synonymous with [[elixir]]s, medicinal [[alchemy]], and the [[philosopher's stone]] itself.<ref>''The Dictionary of Alchemy'', Mark Haeffner.</ref>
 ==Legacy==
 {{main|Aether theories}}
-With the [[History of physics#18th-century developments|18th century physics developments]], physical models known as "aether theories" made use of a similar concept for the explanation of the propagation of electromagnetic and gravitational forces. As early as the 1670s, Newton used the idea of aether to help match observations to strict mechanical rules of his physics.<ref>Margaret Osler, ''Reconfiguring the World.'' The Johns Hopkins University Press 2010. (155).</ref>{{efn|In a 1675 paper, he also wrote a number of pages speculating that aether may explain how the [[soul]] interacts with the body.<ref>{{cite book|last=Gillispie|first=Charles Coulston|url=https://archive.org/details/edgeofobjectivit00char|title=The Edge of Objectivity: An Essay in the History of Scientific Ideas|publisher=Princeton University Press|year=1960|isbn=0-691-02350-6|location=Princeton, NJ|pages=129–30|author-link=Charles Coulston Gillispie}}</ref>}} The early modern aether had little in common with the aether of classical elements from which the name was borrowed. These aether theories are considered to be scientifically obsolete, as the development of [[special relativity]] showed that [[Maxwell's equations]] do not require the aether for the transmission of these forces. Einstein noted that his own model which replaced these theories could itself be thought of as an aether, as it implied that the empty space between objects had its own physical properties.<ref>Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922)</ref>
+With the [[History of physics#18th-century developments|18th century physics developments]], physical models known as "aether theories" made use of a similar concept for the explanation of the propagation of electromagnetic and gravitational forces. As early as the 1670s, Newton used the idea of aether to help match observations to strict mechanical rules of his physics.<ref>Margaret Osler, ''Reconfiguring the World.'' The Johns Hopkins University Press 2010. (155).</ref>{{efn|In a 1675 paper, he also wrote a number of pages speculating that aether may explain how the [[soul]] interacts with the body.<ref>{{cite book |last=Gillispie |first=Charles Coulston |url=https://archive.org/details/edgeofobjectivit00char |title=The Edge of Objectivity: An Essay in the History of Scientific Ideas |publisher=Princeton University Press |year=1960 |isbn=0-691-02350-6 |location=Princeton, NJ |pages=129–30 |author-link=Charles Coulston Gillispie}}</ref>}} The early modern aether had little in common with the aether of classical elements from which the name was borrowed. These aether theories are considered to be scientifically obsolete, as the development of [[special relativity]] showed that [[Maxwell's equations]] do not require the aether for the transmission of these forces. Einstein noted that his own model which replaced these theories could itself be thought of as an aether, as it implied that the empty space between objects had its own physical properties.<ref>Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922)</ref>
-Despite the early modern aether models being superseded by general relativity, occasionally some physicists have attempted to reintroduce the concept of aether in an attempt to address perceived deficiencies in current physical models.<ref>{{cite journal | last1 = Dirac | first1 = Paul | year = 1951 | title = Is there an Aether? | journal = Nature | volume = 168 | issue = 4282| pages = 906–907 | doi=10.1038/168906a0|bibcode = 1951Natur.168..906D | s2cid = 4288946 }}</ref> One proposed model of [[dark energy]] has been named "[[Quintessence (physics)|quintessence]]" by its proponents, in honor of the classical element.<ref>{{cite journal | last1 = Zlatev | first1 = I. | last2 = Wang | first2 = L. | last3 = Steinhardt | first3 = P. | year = 1999 | title = Quintessence, Cosmic Coincidence, and the Cosmological Constant | url = http://cds.cern.ch/record/358722| journal = Physical Review Letters | volume = 82 | issue = 5| pages = 896–899 | doi = 10.1103/PhysRevLett.82.896 | bibcode=1999PhRvL..82..896Z|arxiv = astro-ph/9807002 | s2cid = 119073006 | type = Submitted manuscript }}</ref> This idea relates to the hypothetical form of dark energy postulated as an explanation of observations of an accelerating universe. It has also been called a [[Fifth force|fifth fundamental force]].
+Despite the early modern aether models being superseded by general relativity, occasionally some physicists have attempted to reintroduce the concept of aether in an attempt to address perceived deficiencies in current physical models.<ref>{{cite journal |last1=Dirac |first1=Paul |year=1951 |title=Is there an Aether? |journal=Nature |volume=168 |issue=4282 |pages=906–907 |doi=10.1038/168906a0 |bibcode=1951Natur.168..906D |s2cid=4288946}}</ref> One proposed model of [[dark energy]] has been named "[[Quintessence (physics)|quintessence]]" by its proponents, in honor of the classical element.<ref>{{cite journal |last1=Zlatev |first1=I. |last2=Wang |first2=L. |last3=Steinhardt |first3=P. |year=1999 |title=Quintessence, Cosmic Coincidence, and the Cosmological Constant |url=https://cds.cern.ch/record/358722 |journal=Physical Review Letters |volume=82 |issue=5 |pages=896–899 |doi=10.1103/PhysRevLett.82.896 |bibcode=1999PhRvL..82..896Z |arxiv=astro-ph/9807002 |s2cid=119073006 |type=Submitted manuscript }}</ref> This idea relates to the hypothetical form of dark energy postulated as an explanation of observations of an accelerating universe. It has also been called a [[Fifth force|fifth fundamental force]].
 ===Aether and light===
@@ Line 34: / Line 34: @@
 The motion of light was a long-standing investigation in physics for hundreds of years before the 20th century. The use of aether to describe this motion was popular during the 17th and 18th centuries, including a theory proposed by [[Johann II Bernoulli]], who was recognized in 1736 with the prize of the French Academy. In his theory, all space is permeated by aether containing "excessively small whirlpools". These whirlpools allow for aether to have a certain elasticity, transmitting vibrations from the corpuscular packets of light as they travel through.<ref>[[E. T. Whittaker|Whittaker, Edmund Taylor]], ''[[A History of the Theories of Aether and Electricity|A History of the Theories of Aether and Electricity from the Age of Descartes to the Close of the 19th Century]]'' (1910), pp. 101-02.</ref>
-This theory of [[luminiferous aether]] would influence the [[wave|wave theory]] of light proposed by [[Christiaan Huygens]], in which light traveled in the form of [[longitudinal waves]]  via an "omnipresent, perfectly elastic medium having zero density, called aether". At the time, it was thought that in order for light to travel through a vacuum, there must have been a medium filling the void through which it could propagate, as sound through air or ripples in a pool. Later, when it was proved that the nature of light wave is [[transverse wave|transverse]] instead of longitudinal, Huygens' theory was replaced by subsequent theories proposed by [[James Clerk Maxwell|Maxwell]], [[Albert Einstein|Einstein]] and [[Louis-Victor de Broglie|de Broglie]], which rejected the existence and necessity of aether to explain the various optical phenomena. These theories were supported by the results of the [[Michelson–Morley experiment]] in which evidence for the motion of aether was conclusively absent.<ref>{{Cite journal |last=Michelson |first=Albert A. |journal = American Journal of Science |volume = 22 |issue=128 |year = 1881 |pages = 120–129 |doi=10.2475/ajs.s3-22.128.120|title=The Relative Motion of the Earth and the Luminiferous Ether |bibcode=1881AmJS...22..120M |s2cid=130423116 |url=https://zenodo.org/record/1450060 }}</ref> The results of the experiment influenced many physicists of the time and contributed to the eventual development of Einstein's [[special relativity|theory of special relativity]].<ref>{{cite journal | last1 = Shankland | first1 = R. S. | year = 1964 | title = Michelson-Morley Experiment | journal = American Journal of Physics | volume = 32 | issue = 1| page = 16 | doi = 10.1119/1.1970063 |bibcode = 1964AmJPh..32...16S }}</ref>
+This theory of [[luminiferous aether]] would influence the [[wave|wave theory]] of light proposed by [[Christiaan Huygens]], in which light traveled in the form of [[longitudinal waves]] via an "omnipresent, perfectly elastic medium having zero density, called aether". At the time, it was thought that in order for light to travel through a vacuum, there must have been a medium filling the void through which it could propagate, as sound through air or ripples in a pool. Later, when it was proved that the nature of light wave is [[transverse wave|transverse]] instead of longitudinal, Huygens' theory was replaced by subsequent theories proposed by [[James Clerk Maxwell|Maxwell]], [[Albert Einstein|Einstein]] and [[Louis-Victor de Broglie|de Broglie]], which rejected the existence and necessity of aether to explain the various optical phenomena. These theories were supported by the results of the [[Michelson–Morley experiment]] in which evidence for the motion of aether was conclusively absent.<ref>{{Cite journal |last=Michelson |first=Albert A. |journal=American Journal of Science |volume=22 |issue=128 |year=1881 |pages=120–129 |doi=10.2475/ajs.s3-22.128.120 |title=The Relative Motion of the Earth and the Luminiferous Ether |bibcode=1881AmJS...22..120M |s2cid=130423116 |url=https://zenodo.org/record/1450060 }}</ref> The results of the experiment influenced many physicists of the time and contributed to the eventual development of Einstein's [[special relativity|theory of special relativity]].<ref>{{cite journal |last1=Shankland |first1=R. S. |year=1964 |title=Michelson-Morley Experiment |journal=American Journal of Physics |volume=32 |issue=1 |page=16 |doi=10.1119/1.1970063 |bibcode=1964AmJPh..32...16S }}</ref>
 ===Aether and gravitation===
 [[File:Bernoulli - De gravitate aetheris, 1683 - 1216514.jpg|thumb|upright|[[Jakob Bernoulli]], ''De gravitate aetheris'', 1683]]
-In 1682, [[Jakob Bernoulli]] formulated the theory that the hardness of the bodies depended on the pressure of the aether.<ref>{{Cite web|url=http://www.treccani.it/enciclopedia/bernoulli|title=Bernoulli nell'Enciclopedia Treccani}}</ref>
+In 1682, [[Jakob Bernoulli]] formulated the theory that the hardness of the bodies depended on the pressure of the aether.<ref>{{Cite web |url=http://www.treccani.it/enciclopedia/bernoulli|title=Bernoulli nell'Enciclopedia Treccani}}</ref>
 Aether has been used in various gravitational theories as a medium to help explain gravitation and what causes it.
 [[File:GodfreyKneller-IsaacNewton-1689.jpg|thumb|left|upright|Sir [[Isaac Newton]]]]
-A few years later, aether was used in one of Sir [[Isaac Newton]]'s first published theories of gravitation, ''[[Philosophiæ Naturalis Principia Mathematica]]'' (the ''Principia'', 1687). He based the whole description of planetary motions on a theoretical law of dynamic interactions. He renounced standing attempts at accounting for this particular form of interaction between distant bodies by introducing a mechanism of propagation through an intervening medium.<ref name="Rosenfeld1969">{{cite journal |last1=Rosenfeld |first1=L. |title=Newton's views on aether and gravitation |journal=Archive for History of Exact Sciences |date=1969 |volume=6 |issue=1 |pages=29–37 |doi=10.1007/BF00327261|s2cid=122494617 }}</ref> He calls this intervening medium aether. In his aether model, Newton describes aether as a medium that "flows" continually downward toward the Earth's surface and is partially absorbed and partially diffused. This "circulation" of aether is what he associated the force of gravity with to help explain the action of gravity in a non-mechanical fashion.<ref name="Rosenfeld1969"/> This theory described different aether densities, creating an aether density gradient. His theory also explains that aether was dense within objects and rare without them. As particles of denser aether interacted with the rare aether they were attracted back to the dense aether much like cooling vapors of water are attracted back to each other to form water.<ref name="newton1679"/> In the ''Principia'' he attempts to explain the elasticity and movement of aether by relating aether to his static model of fluids. This elastic interaction is what caused the pull of gravity to take place, according to this early theory, and allowed an explanation for action at a distance instead of action through direct contact. Newton also explained this changing rarity and density of aether in his letter to [[Robert Boyle]] in 1679.<ref name="newton1679">Newton, Isaac.[http://www.orgonelab.org/newtonletter.htm "Isaac Newton to Robert Boyle, 1679."] 28 February 1679.</ref> He illustrated aether and its field around objects in this letter as well and used this as a way to inform Robert Boyle about his theory.<ref name="letter">{{cite web|url=http://www.orgonelab.org/newtonletter.htm |title=Isaac Newton's Letter to Robert Boyle, on the Cosmic Ether of Space - 1679 |author=James DeMeo |year=2009 |website=orgonelab.org |access-date=20 December 2016 |archive-url=https://web.archive.org/web/20161220231449/http://www.orgonelab.org/newtonletter.htm |archive-date=20 December 2016 |url-status=live }}</ref> Although Newton eventually changed his theory of gravitation to one involving force and the laws of motion, his starting point for the modern understanding and explanation of gravity came from his original aether model on gravitation.<ref name="robishaw">{{cite book |url=https://books.google.com/books?id=KkS9CQAAQBAJ&q=newton+robert+boyle+aether&pg=PA6 |title=The Esoteric Codex: Esoteric Cosmology |author=Andrew Robishaw |page=6 |date=9 April 2015 |publisher=Lulu.com |access-date=20 December 2016 |isbn=9781329053083}}{{self-published source|date=December 2020}}</ref>{{self-published inline|date=February 2020}}
+A few years later, aether was used in one of Sir [[Isaac Newton]]'s first published theories of gravitation, ''[[Philosophiæ Naturalis Principia Mathematica]]'' (the ''Principia'', 1687). He based the whole description of planetary motions on a theoretical law of dynamic interactions. He renounced standing attempts at accounting for this particular form of interaction between distant bodies by introducing a mechanism of propagation through an intervening medium.<ref name="Rosenfeld1969">{{cite journal |last1=Rosenfeld |first1=L. |title=Newton's views on aether and gravitation |journal=Archive for History of Exact Sciences |date=1969 |volume=6 |issue=1 |pages=29–37 |doi=10.1007/BF00327261 |s2cid=122494617}}</ref> He calls this intervening medium aether. In his aether model, Newton describes aether as a medium that "flows" continually downward toward the Earth's surface and is partially absorbed and partially diffused. This "circulation" of aether is what he associated the force of gravity with to help explain the action of gravity in a non-mechanical fashion.<ref name="Rosenfeld1969"/> This theory described different aether densities, creating an aether density gradient. His theory also explains that aether was dense within objects and rare without them. As particles of denser aether interacted with the rare aether they were attracted back to the dense aether much like cooling vapors of water are attracted back to each other to form water.<ref name="newton1679"/> In the ''Principia'' he attempts to explain the elasticity and movement of aether by relating aether to his static model of fluids. This elastic interaction is what caused the pull of gravity to take place, according to this early theory, and allowed an explanation for action at a distance instead of action through direct contact. Newton also explained this changing rarity and density of aether in his letter to [[Robert Boyle]] in 1679.<ref name="newton1679">Newton, Isaac.[http://www.orgonelab.org/newtonletter.htm "Isaac Newton to Robert Boyle, 1679."] 28 February 1679.</ref> He illustrated aether and its field around objects in this letter as well and used this as a way to inform Robert Boyle about his theory.<ref name="letter">{{cite web |url=http://www.orgonelab.org/newtonletter.htm |title=Isaac Newton's Letter to Robert Boyle, on the Cosmic Ether of Space - 1679 |author=James DeMeo |year=2009 |website=orgonelab.org |access-date=20 December 2016 |archive-url=https://web.archive.org/web/20161220231449/http://www.orgonelab.org/newtonletter.htm |archive-date=20 December 2016 |url-status=live}}</ref> Although Newton eventually changed his theory of gravitation to one involving force and the laws of motion, his starting point for the modern understanding and explanation of gravity came from his original aether model on gravitation.<ref name="robishaw">{{cite book |url=https://books.google.com/books?id=KkS9CQAAQBAJ&q=newton+robert+boyle+aether&pg=PA6 |title=The Esoteric Codex: Esoteric Cosmology |author=Andrew Robishaw |page=6 |date=9 April 2015 |publisher=Lulu.com |access-date=20 December 2016 |isbn=9781329053083}}{{self-published source|date=December 2020}}</ref>{{self-published inline|date=February 2020}}
 ==See also==
+{{Div col|small=no}}
 * [[Akasha]]
 * [[Celestial spheres]]
@@ Line 56: / Line 57: @@
 * [[Prana]]
 * [[Radiant energy]]
+{{Div col end}}
 ==References==
@@ Line 64: / Line 66: @@
 {{Reflist|30em}}
+[[de:Quintessenz (Philosophie)]]
 [[Category:Aether theories]]
 [[Category:Classical elements]]
@@ Line 70: / Line 73: @@
 [[Category:History of science]]
 [[Category:Mythological substances]]
-[[Category:Theories in ancient Greek philosophy]]
+[[Category:Concepts in ancient Greek metaphysics]]
+[[Category:Words and phrases derived from Greek mythology]]
-[[es:Éter (física)]]
-[[fr:Éther (physique)]]

Classical elements
Hellenistic Air Water Aether Fire Earth
Hinduism / Jainism / Buddhism Vayu Ap Akasha Agni Prithvi
Chinese Wood (木) Water (水) Fire (火) Metal (金) Earth (土)
Japanese Wind (風) Water (水) Void (空) Fire (火) Earth (地)
European alchemy Air Water Fire Aether Earth Sulphur Mercury Salt
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