Aether (classical element)

According to ancient and medieval science, aether (Ancient Greek: αἰθήρ, aither[1]), also spelled æther or ether and also called quintessence, is the material that fills the region of the universe above the terrestrial sphere.[2] 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.[3]

Mythological origins

The word αἰθήρ (aithēr) in Homeric Greek means "pure, fresh air" or "clear sky". 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.[4][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 (αίθηρ)".[9] but otherwise he adopted the classical system of four elements. Aristotle, who had been Plato's student at the Akademia, agreed on this point with his former mentor, emphasizing additionally that fire sometimes has 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 not used.[10]

Aether did not follow Aristotelian physics either. Aether was also 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.[11] Aristotle also noted that crystalline spheres made of aether held the celestial bodies. The idea of crystalline spheres and natural circular motion of aether led to Aristotle's explanation of the observed orbits of stars and planets in perfectly circular motion in crystalline aether.[2]

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 of the character that it was "subtler than light". Fludd cites the 3rd-century view of Plotinus, concerning the aether as penetrative and non-material.[13] See also Arche.


Quintessence 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.[14] This theory was developed in the 14th century text The testament of Lullius, attributed to Ramon Llull. 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.[14] 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.[15] Over the years, the term quintessence has become synonymous with elixirs, medicinal alchemy, and the philosopher's stone itself.[16]


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.[17] However, 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. However, Einstein himself 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.[18]

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.[19] One proposed model of dark energy has been named "quintessence" by its proponents, in honor of the classical element.[20] This idea relates to the hypothecial 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.[21]

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.[22] The results of the experiment influenced many physicists of the time and contributed to the eventual development of Einstein's theory of special relativity.[23]

Aether and gravitation

Sir Isaac Newton

Aether has been used in various gravitational theories as a medium to help explain gravitation and what causes it. It was used in one of Sir Isaac Newton's first published theories of gravitation, Philosophiæ Naturalis Principia Mathematica (the Principia). 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.[24] 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.[24] 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.[25] 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.[25] 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.[26] 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.[27]

See also


  1. ^ "ether". The American Heritage Dictionary of the English Language (4th ed.). Boston: Houghton Mifflin. 2006. ISBN 978-0618701728.
  2. ^ a b George Smoot III. "Aristotle's Physics". Archived from the original on 20 December 2016. Retrieved 20 December 2016.
  3. ^ Carl S. Helrich, The Classical Theory of Fields: Electromagnetism Berlin, Springer 2012, p. 26.
  4. ^ a b "Aether". Archived from the original on 20 December 2016. Retrieved 20 December 2016.
  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. 1818.
  8. ^ Fage, John (2013-10-23). A History of Africa. Routledge. pp. 25–26. ISBN 978-1317797272. 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. doi:10.2307/631126. JSTOR 631126.
  11. ^ G. E. R. Lloyd), Aristotle: The Growth and Structure of his Thought, Cambridge: Cambridge Univ. Pr., 1968, pp. 133-139, ISBN 0-521-09456-9.
  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. Pg 221.
  14. ^ a b The Alchemists, by F. Sherwood Taylor page 95
  15. ^ The book of Quintessence, Early English Text society original series number 16, edited by F. J. Furnivall
  16. ^ The Dictionary of Alchemy, by Mark Haeffner
  17. ^ Margaret Osler, Reconfiguring the World. The Johns Hopkins University Press 2010. (155).
  18. ^ Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922)
  19. ^ Dirac, Paul (1951). "Is there an Aether?". Nature. 168 (4282): 906–907. Bibcode:1951Natur.168..906D. doi:10.1038/168906a0.
  20. ^ 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.
  21. ^ 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.
  22. ^ 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.
  23. ^ Shankland, R. S. (1964). "Michelson-Morley Experiment". American Journal of Physics. 32 (1): 16. Bibcode:1964AmJPh..32...16S. doi:10.1119/1.1970063.
  24. ^ 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.
  25. ^ a b Newton, Isaac."Isaac Newton to Robert Boyle, 1679." 28 February 1679.
  26. ^ James DeMeo (2009). "Isaac Newton's Letter to Robert Boyle, on the Cosmic Ether of Space - 1679". Archived from the original on 20 December 2016. Retrieved 20 December 2016.
  27. ^ Andrew Robishaw (9 April 2015). The Esoteric Codex: Esoteric Cosmology. p. 6. ISBN 9781329053083. Retrieved 20 December 2016.
Absolute (philosophy)

In philosophy, the concept of The Absolute, also known as Brahman, The (Unconditioned) Ultimate, The Wholly Other, The Supreme Being, The Absolute/Ultimate Reality, and other names, is the thing, being, entity, power, force, reality, presence, law, principle, etc. that possesses maximal ontological status, existential ranking, existential greatness, or existentiality. In layman's terms, this is the one that is, in one way or another, the greatest, truest, or most real being.

There are many conceptions of The Absolute in various fields and subjects, such as philosophy, religion, spiritual traditions, mathematics, and even natural science. The nature of these conceptions can range from "merely" encompassing all physical existence, nature, or reality, to being completely unconditioned existentially, transcending all concepts, notions, and types, kinds, and categories of being.

The Absolute is often thought of as causing to come into being manifestations that interact with lower or lesser forms of being. This is either done passively, through emanations, or actively, through avatars and incarnations. These existential manifestations, which themselves can possess transcendent attributes, only contain minuscule or infinitesimal portions of the true essence of The Absolute.

The term itself was not in use in ancient or medieval philosophy, but closely related to the description of God as Actus purus (Pure Actuality) in scholasticism. It was introduced in modern philosophy, notably by Hegel, for "the sum of all being, actual and potential".

The term has since also been adopted in perennial philosophy.

Aether theories

In physics, aether theories (also known as ether theories) propose the existence of a medium, a space-filling substance or field, the aether (also spelled ether) thought to be necessary as a transmission medium for the propagation of electromagnetic or gravitational forces.

Since the development of special relativity, theories using a substantial aether fell out of use in modern physics, and are now joined by more abstract models.This early modern aether has little in common with the aether of classical elements from which the name was borrowed. The assorted theories embody the various conceptions of this medium and substance.


Aither may refer to:

Aether (classical element), the material supposed to fill the region of the universe above the terrestrial sphere

Aether (mythology), the personification of the "upper sky", space and heaven, in Greek mythology


Akasha (Sanskrit ākāśa आकाश) is a term for either space or æther in traditional Indian cosmology, depending on the religion. The term has also been adopted in Western occultism and spiritualism in the late 19th century. In Hindustani, Nepali, Bengali, Marathi, Kannada, Telugu, Tamil it means "sky". In many modern Indo-Aryan languages and Dravidian languages the corresponding word (often rendered Akash) retains a generic meaning of "sky".

Energy (esotericism)

The term "energy" is used by writers and practitioners of various esoteric forms of spirituality and alternative medicine to refer to a variety of phenomena. There is no scientific evidence for the existence of such energy.Therapies that purport to use, modify, or manipulate unknown energies are thus among the most contentious of all complementary and alternative medicines. Claims related to energy therapies are most often anecdotal (from single stories), rather than being based on repeatable empirical evidence.

Etheric plane

The etheric plane (see also etheric body) is a term introduced into Theosophy by Charles Webster Leadbeater and Annie Besant to represent the subtle part of the lower plane of existence. It represents the fourth [higher] subplane of the physical plane (a hyperplane), the lower three being the states of solid, liquid, and gaseous matter. The idea was later used by authors such as Alice Bailey, Rudolf Steiner, Walter John Kilner and others.

The term aether (also written as "ether") was adopted from ancient Greek philosophy and science into Victorian physics (see Luminiferous aether) and utilised by Madame Blavatsky to correspond to akasha, the fifth element (quintessence) of Hindu metaphysics.

The Greek word aither derives from an Indo-European root aith- ("burn, shine"). Blavatsky also related the idea to the Hindu Prana principle, the vital, life-sustaining force of living beings, present in all natural processes of the universe. Prana was first expounded in the Upanishads, where it is part of the worldly, physical realm, sustaining the body and the mind. Blavatsky also tended to use the word "astral" indiscriminately for these supposed subtle physical phenomena. The esoteric concepts of Adi, the Buddhic plane, the causal plane, and the monadic plane are also related to that of the etheric plane.Leadbeater and Besant (both belonging to the Adyar School of Theosophy) conceived that the etheric plane constituted four higher subplanes of the physical plane. According to the Theosophist Geoffrey A. Farthing, Leadbeater used the term, because of its resonance in the physical sciences, to describe his clairvoyant investigations of sub-atomic physics.

Index of ancient philosophy articles

This page is a list of topics in ancient philosophy.

Index of physics articles (A)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

List of discredited substances

This page is a list of substances or materials generally considered discredited.

A substance can be discredited in one of three ways:

It was widely believed to exist at one time but no longer is. Such substances are often part of an obsolete scientific theory.

It was once believed to have drastically different properties from those accepted now. It was widely claimed and believed to possess significant properties that are no longer attributed to it.

It is currently believed to exist as part of a theory that has not met the theoretical and experimental requirements of mainstream science. In particular, such a theory must be predictive.

Luminiferous aether

Luminiferous aether or ether ("luminiferous", meaning "light-bearing"), was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light.

The aether hypothesis was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects. As the nature of light was explored, especially in the 19th century, the physical qualities required of an aether became increasingly contradictory. By the late 1800s, the existence of the aether was being questioned, although there was no physical theory to replace it.

The negative outcome of the Michelson–Morley experiment (1887) suggested that the aether did not exist, a finding that was confirmed in subsequent experiments through the 1920s. This led to considerable theoretical work to explain the propagation of light without an aether. A major breakthrough was the theory of relativity, which could explain why the experiment failed to see aether, but was more broadly interpreted to suggest that it was not needed. The Michelson-Morley experiment, along with the blackbody radiator and photoelectric effect, was a key experiment in the development of modern physics, which includes both relativity and quantum theory, the latter of which explains the wave-like nature of light.


The occult (from the Latin word occultus "clandestine, hidden, secret") is "knowledge of the hidden" or "knowledge of the paranormal", as opposed to facts and "knowledge of the measurable", usually referred to as science. The term is sometimes taken to mean knowledge that "is meant only for certain people" or that "must be kept hidden", but for most practicing occultists it is simply the study of a deeper spiritual reality that extends pure reason and the physical sciences. The terms esoteric and arcane can also be used to describe the occult, in addition to their meanings unrelated to the supernatural.

The term occult sciences was used in the 16th century to refer to astrology, alchemy, and natural magic. The term occultism emerged in 19th-century France, where it came to be associated with various French esoteric groups connected to Éliphas Lévi and Papus, and in 1875 was introduced into the English language by the esotericist Helena Blavatsky. Throughout the 20th century, the term was used idiosyncratically by a range of different authors, but by the 21st century was commonly employed – including by academic scholars of esotericism – to refer to a range of esoteric currents that developed in the mid-19th century and their descendants. Occultism is thus often used to categorise such esoteric traditions as Spiritualism, Theosophy, Anthroposophy, the Hermetic Order of the Golden Dawn, and New Age.

Particularly since the late twentieth century, various authors have used the occult as a substantivized adjective. In this usage, "the occult" is a category into which varied beliefs and practices are placed if they are considered to fit into neither religion nor science. "The occult" in this sense is very broad, encompassing such phenomenon as beliefs in vampires or fairies and movements like Ufology and parapsychology. In that same period, occult and culture were combined to form the neologism occulture. Initially used in the industrial music scene, it was later given scholarly applications.

Odic force

The Odic force (also called Od [õd], Odyle, Önd, Odes, Odylic, Odyllic, or Odems) is the name given in the mid-19th century to a hypothetical vital energy or life force by Baron Carl von Reichenbach. Von Reichenbach coined the name from that of the Norse god Odin in 1845. The study of Odic force is called odology.


In traditional Chinese culture, qi or ch'i (Chinese: 气; pinyin: qì qì) is believed to be a vital force forming part of any living entity. Qi translates as "air" and figuratively as "material energy", "life force", or "energy flow". Qi is the central underlying principle in Chinese traditional medicine and in Chinese martial arts. The practice of cultivating and balancing qi is called qigong.

Believers of qi describe it as a vital energy, the flow of which must be balanced for health. Qi is a pseudoscientific, unverified concept, which has never been directly observed, and is unrelated to the concept of energy used in science (vital energy is itself an abandoned scientific notion).

Quintessence (physics)

In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of the observation of an accelerating rate of expansion of the universe. The first example of this scenario was proposed by Ratra and Peebles (1988). The concept was expanded to more general types of time-varying dark energy and the term "quintessence" was first introduced in a paper by Robert R. Caldwell, Rahul Dave and Paul Steinhardt.

It has been proposed by some physicists to be a fifth fundamental force. Quintessence differs from the cosmological constant explanation of dark energy in that it is dynamic; that is, it changes over time, unlike the cosmological constant which, by definition, does not change.

It is suggested that quintessence can be either attractive or repulsive depending on the ratio of its kinetic and potential energy. Those working with this postulate believe that quintessence became repulsive about ten billion years ago, about 3.5 billion years after the Big Bang.

Theoretical physics

Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena.

The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigor while giving little weight to experiments and observations. For example, while developing special relativity, Albert Einstein was concerned with the Lorentz transformation which left Maxwell's equations invariant, but was apparently uninterested in the Michelson–Morley experiment on Earth's drift through a luminiferous ether. Conversely, Einstein was awarded the Nobel Prize for explaining the photoelectric effect, previously an experimental result lacking a theoretical formulation.


The Coming Race is a novel by Edward Bulwer-Lytton, published anonymously in 1871. It has also been published as Vril, the Power of the Coming Race.

Some readers have believed the account of a superior subterranean master race and the energy-form called "Vril", at least in part; some theosophists, notably Helena Blavatsky, William Scott-Elliot, and Rudolf Steiner, accepted the book as based on occult truth, in part. One 1960 book, The Morning of the Magicians, suggested that a secret Vril Society existed in Weimar Berlin. However, there is no evidence for the existence of such a society.

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