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Emission Theory (vision)
Emission theory or extramission theory (variants: extromission) or extromissionism is the proposal that visual perception is accomplished by eye beams emitted by the eyes. This theory has been replaced by ''intromission theory'' (or '' intromissionism''), which is that visual perception comes from something representative of the object (later established to be rays of light reflected from it) entering the eyes. Modern physics has confirmed that light is physically transmitted by photons from a light source, such as the sun, to visible objects, and finishing with the detector, such as a human eye or camera. History In the fifth century BC, Empedocles postulated that everything was composed of four elements; fire, air, earth, and water. He believed that Aphrodite made the human eye out of the four elements and that she lit the fire in the eye which shone out from the eye, making sight possible. If this were true, then one could see during the night just as well as during the day, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucretius
Titus Lucretius Carus ( , ; – ) was a Roman poet and philosopher. His only known work is the philosophical poem ''De rerum natura'', a didactic work about the tenets and philosophy of Epicureanism, and which usually is translated into English as ''On the Nature of Things''—and somewhat less often as ''On the Nature of the Universe''. Lucretius has been credited with originating the concept of the three-age system that was formalised in 1836 by C. J. Thomsen. Very little is known about Lucretius's life; the only certainty is that he was either a friend or client of Gaius Memmius, to whom the poem was addressed and dedicated. ''De rerum natura'' was a considerable influence on the Augustan poets, particularly Virgil (in his ''Aeneid'' and ''Georgics'', and to a lesser extent on the ''Eclogues'') and Horace. The work was almost lost during the Middle Ages, but was rediscovered in 1417 in a monastery in Germany by Poggio Bracciolini and it played an important role both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the greatest mathematicians and physicists and among the most influential scientists of all time. He was a key figure in the philosophical revolution known as the Enlightenment. His book (''Mathematical Principles of Natural Philosophy''), first published in 1687, established classical mechanics. Newton also made seminal contributions to optics, and shares credit with German mathematician Gottfried Wilhelm Leibniz for developing infinitesimal calculus. In the , Newton formulated the laws of motion and universal gravitation that formed the dominant scientific viewpoint for centuries until it was superseded by the theory of relativity. Newton used his mathematical description of gravity to derive Kepler's laws of planetary motion, account for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alhazen
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the principal Arab mathematicians and, without any doubt, the best physicist.") , ("Ibn al-Ḥaytam was an eminent eleventh-century Arab optician, geometer, arithmetician, algebraist, astronomer, and engineer."), ("Ibn al-Haytham (d. 1039), known in the West as Alhazan, was a leading Arab mathematician, astronomer, and physicist. His optical compendium, Kitab al-Manazir, is the greatest medieval work on optics.") Referred to as "the father of modern optics", he made significant contributions to the principles of optics and visual perception in particular. His most influential work is titled '' Kitāb al-Manāẓir'' (Arabic: , "Book of Optics"), written during 1011–1021, which survived in a Latin edition. Ibn al-Haytham was an early propo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thesaurus Opticus Titelblatt
A thesaurus (plural ''thesauri'' or ''thesauruses'') or synonym dictionary is a reference work for finding synonyms and sometimes antonyms of words. They are often used by writers to help find the best word to express an idea: Synonym dictionaries have a long history. The word 'thesaurus' was used in 1852 by Peter Mark Roget for his ''Roget's Thesaurus''. While some thesauri, such as ''Roget's Thesaurus'', group words in a hierarchy, hierarchical hypernym, hypernymic taxonomy (general), taxonomy of concepts, others are organized alphabetically or in some other way. Most thesauri do not include definitions, but many dictionaries include listings of synonyms. Some thesauri and dictionary synonym notes characterize the distinctions between similar words, with notes on their "connotations and varying shades of meaning".''American Heritage Dictionary of the English Language'', 5th edition, Houghton Mifflin Harcourt 2011, , p. xxvii Some synonym dictionaries are primarily concerned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit for the speed at which conventional matter or energy (and thus any signal carrying information) can travel through space. All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and very sensitive measurements, their finite speed has noticeable effects. Starlight viewed on Earth left the stars many years ago, allowing humans to study the history of the universe by viewing distant objects. When communicating with distant space probes, it can take minutes to hours for signals to travel from Earth to the spacecraft and vice versa. In computing, the speed of light fixes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gezienus Ten Doesschate
Gezienus (or Gesinus) ten Doesschate (11 August 1885, Zwolle – 9 March 1965, Utrecht) was a Dutch ophthalmologist, amateur painter and historian. He was active as an amateur painter in Utrecht under the pseudonym Thomas Denier. He had good contacts with the cultural elite of Utrecht around the First World War and was good friends with the painters Janus de Winter and . In 1916 he was briefly a member of ''de Anderen,'' a Dutch artists' group that included Theo van Doesburg Theo van Doesburg (, 30 August 1883 – 7 March 1931) was a Dutch artist, who practiced painting, writing, poetry and architecture. He is best known as the founder and leader of De Stijl. He was married to artist, pianist and choreographer Nelly ..., but dropped out in support of ''de Winter,'' another artists group. At the end of his life he contributed to a number of medical-historical books concerning the University of Utrecht. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tapetum Lucidum
The ''tapetum lucidum'' ( ; ; ) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors (although slightly blurring the image). The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep sea animals. Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a ''tapetum lucidum''. Function and mechanism Presence of a ''tapetum lucidum'' enables animals to see in dimmer light than would otherwise be possible. The ''tapetum lucidum'', which is iridescent, reflects light roughly on the interference principles of thin-film optics, as seen in other iridescent tissues. However, the ''tapetum lucidum'' cells are leucophores, not iridophores. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galenic Corpus
The Galenic corpus is the collection of writings of Galen, a prominent Greek physician, surgeon and philosopher in the Roman Empire during the second century CE. Several of the works were written between 165–175 CE. Description Galen produced more work than any author in antiquity,Kotrc RF, Walters KR. "A bibliography of the Galenic Corpus. A newly researched list and arrangement of the titles of the treatises extant in Greek, Latin, and Arabic". ''Trans Stud Coll Physicians Philad''. 1979 Dec;1(4): 256-304 His surviving work runs to over 2.6 million words, and many more of his writings are now lost. Karl Gottlob Kühn of Leipzig (1754–1840) published an edition of 122 of Galen's writings between 1821 and 1833. His edition, which is the most complete, although flawed, consists of the Greek text with facing-page Latin translation. The text and translation are mainly taken from the edition of Chartier 1638—39, Paris. Kühn's edition runs to 22 volumes, 676 index pages, be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galen
Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one of the most accomplished of all medical researchers of antiquity, Galen influenced the development of various scientific disciplines, including anatomy, physiology, pathology, pharmacology, and neurology, as well as philosophy and logic. The son of Aelius Nicon, a wealthy Greek architect with scholarly interests, Galen received a comprehensive education that prepared him for a successful career as a physician and philosopher. Born in the ancient city of Pergamon (present-day Bergama, Turkey), Galen traveled extensively, exposing himself to a wide variety of medical theories and discoveries before settling in Rome, where he served prominent members of Roman society and eventually was given the position of personal physician to several emp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optics (Ptolemy)
Ptolemy's ''Optics'' is a 2nd-century book on geometrical optics, dealing with Reflection (physics), reflection, refraction, and colour. The book was most likely written late in Ptolemy's life, after the ''Almagest'', during the 160s. The work is of great importance in the early history of optics. The Greek text has been lost completely. Fragments of the work survive only in the form of a Latin translations of the 12th century, Latin translation, prepared around 1154 by Eugene of Palermo, based on an Arabic translation which was presumably based on the Greek original. Both the Arabic and the Greek texts are lost entirely, and the Latin text is "badly mangled". The Latin text was edited by Albert Lejeune in 1956. The 1996 English translation by Mark Smith is based on Lejeune's Latin text. Textual history The work is known to have been received by Arabic scholars working on optics in the 10th and 11th century, specifically Ibn Sahl (mathematician), Ibn Sahl ( 984) and Ibn Al-Haytha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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