optics

A telescope (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') is an optical tool which gathers and focuses electromagnetic radiation. Telescopes increase the apparent angular size of distant objects, as well as their apparent brightness. Telescopes are used for astronomy and in many non-astronomical instruments including theodolites, transits, spotting scopes, monoculars, binoculars, camera lenses and spyglasses. The word "telescope" usually refers to optical telescopes, but there are telescopes for mo ...

Including:

• Telescope - History
• Telescope - Types
• Telescope - Telescope mountings
• Telescope - Research telescopes
• Telescope - Imperfect images
• Telescope - The five Seidel aberrations
• Telescope - The chromatic aberrations
• Telescope - Famous optical telescopes
• Telescope - Related lists

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Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength. The three basic dimensions of light (i.e., all electromagnetic radiation) are: Intensity (or brilliance or amplitude), which is related to the human perception of brightness of the light, Frequency (or wavelength), perceived by humans as the color of the light, and Polarization (or angle of vibration), which is not perceptible by ...

Including:

• Light - Visible electromagnetic radiation
• Light - Speed of light
• Light - Refraction
• Light - Optics
• Light - Color and wavelengths
• Light - Measurement of light
• Light - Light sources
• Light - Theories about light
• Light - Early Greek ideas
• Light - 10th century optical theory
• Light - The 'plenum'
• Light - Particle theory
• Light - Wave theory
• Light - Electromagnetic theory
• Light - Particle theory revisited
• Light - Quantum theory
• Light - Wave-particle duality
• Light - A light wave

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A distortion is the (usually) undesirable alteration of the original shape (or other characteristic) of an object, image, sound, waveform or other form of information or representation. Distortion is sometimes denoted as the amount of difference between the entity's original shape and its altered shape and can be quantified as a percentage of the magnitude of the original entity. Distortion - Optics. In optics, distortion is a divergence from rectilinear projection caused by a change in magnification ...

Including:

• Distortion - Optics
• Distortion - Map projections
• Distortion - Electronic signals
• Distortion - Amplitude distortion
• Distortion - Frequency distortion
• Distortion - Phase distortion
• Distortion - Group delay distortion
• Distortion - Teletypewriter signaling
• Distortion - Audio distortion
• Distortion - Guitar distortion

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Sir Isaac Newton, PRS (4 January [O.S. 25 December 1642] 1643 – 31 March [O.S. 20 March] 1727) was an English physicist, mathematician, astronomer, alchemist, and natural philosopher who is regarded by many as the most influential scientist in history. Most importantly, Newton wrote the Philosophiae Naturalis Principia Mathematica wherein he described universal gravitation and the three laws of motion, laying the groundwork for classical mechanics. By deriving Kepler's laws of planetary mo ...

Including:

• Isaac Newton - Biography
• Isaac Newton - Early years
• Isaac Newton - Middle years
• Isaac Newton - Later life
• Isaac Newton - Religious views
• Isaac Newton - Newton's effect on religious thought
• Isaac Newton - Newton versus the counterfeiters
• Isaac Newton - Enlightenment philosophers
• Isaac Newton - Newton's legacy
• Isaac Newton - Newton's apple
• Isaac Newton - Fictional appearances
• Isaac Newton - Writings by Newton
• Isaac Newton - Notes
• Isaac Newton - Resources
• Isaac Newton - References
• Isaac Newton - Further reading
• Isaac Newton - External links

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Enochian is an occult language popularised by John Dee and Edward Kelley in the 16th Century. Dee and Kelley claimed that it was revealed to them by angels, though most contemporary practitioners of magick consider it a constructed language. The name "Enochian" is a reference to the Book of Enoch, a pseudepigraphal text and a major source of Judeo-Christian angelology. Enochian - Dee's Enochian. Dee began to allude to his search for knowledge through the angels in 1581 when he mentioned in his person ...

Including:

• Enochian - Dee's Enochian
• Enochian - Enochian Tradition
• Enochian - Trithemius's Angelic Script
• Enochian - Agrippa's Angelic Alphabets
• Enochian - Pantheus's Enoch
• Enochian - Influence of Ethiopian upon Enochian
• Enochian - Linguistic Analysis of Dee's Enochian
• Enochian - Modern Enochian Derivations

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In the eye, the pupil is the opening in the middle of the iris. It appears black because most of the light entering it is absorbed by the tissues inside the eye. In humans and many animals (but few fish), the size of the pupil is controlled by involuntary contraction and dilation of the iris, in order to regulate the intensity of light entering the eye. This is known as the pupillary reflex. In bright light, the human pupil has a diameter of about 1.5 millimeter, in dim light the diameter is enlarged to about 8 millimeter. The ...

Including:

• Pupil - Dilation of the pupil
• Pupil - Constriction of the pupil

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Coincidence literally describes two or more events or entities occupying the same point in space or time, but colloquially means two or more events or entities possessing unexpected parallels, such as thinking about someone and then receiving an unexpected phone call from that person, when it is clear that there is no ordinary causal connection. The index of coincidence can be used to analyze whether two events are related. A coincidence does not prove a relationship, but related events may be expected to have a higher index of ...

Including:

• Coincidence - Types of Coincidences
• Coincidence - Examples
• Coincidence - Separated twins and coincidences
• Coincidence - Coincidences and Conspiracies

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Alhazen Abu Ali al-Hasan Ibn Al-Haitham (also: Ibn al Haythen), (965-1040), was a mathematician; he is sometimes called al-Basri, after his birthplace Basrah, Iraq. Alhazen - Life. Alhazen was born at Basra, then part of Buwayhid Persia, now part of Iraq (See [1] and [2]), and probably died in Cairo, Egypt. One account of his career has him summoned to Egypt by the mercurial caliph Hakim to regulate the flooding of the Nile. After his field work made him aware of the impracticality of t ...

Including:

• Alhazen - Life
• Alhazen - Works
• Alhazen - Optics
• Alhazen - Other Alhazens
• Alhazen - Bibliography

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The letter F is the sixth letter in the Latin alphabet. Its name in English is ef, spelled eff when used as a verb. On keyboards, often the F and J keys (or occasionally the D and K keys) have a raised dot or bar on their surface, perceptible to the touch, to assist in typing, especially for the blind. All other keys can be found with their relative positions around these two keys as the index finger normally rests on F and J keys (or the middle finger in the case of D and K). F - Hi ...

Including:

• F - History
• F - Phonetic use
• F - Alternative representations
• F - Computing
• F - Ligatures
• F - Meanings for F
• F - Variants of F

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The Annus Mirabilis Papers (from Annus mirabilis, Latin for 'year of wonders') are the papers of Albert Einstein submitted to the "Annalen der Physik" journal in 1905. The four articles provided a foundation for modern physics. Annus Mirabilis Papers - Papers. Three of those papers (on Brownian motion, the photoelectric effect, and special relativity) deserved Nobel Prizes according to some physicists. Only the paper on the photoelectric effect would win one. What makes these papers remarkable ...

Including:

• Annus Mirabilis Papers - Papers
• Annus Mirabilis Papers - Background
• Annus Mirabilis Papers - Photoelectric effect
• Annus Mirabilis Papers - Brownian motion
• Annus Mirabilis Papers - Special relativity
• Annus Mirabilis Papers - Matter and energy equivalence
• Annus Mirabilis Papers - Commemoration

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Alchemy is an early protoscientific and philosophical discipline combining the elements of chemistry, metallurgy, physics, medicine, astrology, semiotics, mysticism, and art. Alchemy has been practiced in ancient Egypt, India, and China, in Classical Greece and Rome, in the Islamic Empire, and then in Europe up to the 19th century — in a complex network of schools and philosophical systems spanning at least 2500 years. The alchemists did not follow what is now known as the scientific method, and much of the "knowledge" they p ...

Including:

• Alchemy - Overview
• Alchemy - Alchemy as a proto-science
• Alchemy - The changing goals of alchemy
• Alchemy - Alchemy and astrology
• Alchemy - Alchemy in the age of science
• Alchemy - Alchemy as a subject of historical research
• Alchemy - Etymology
• Alchemy - History
• Alchemy - Alchemy in Ancient Egypt
• Alchemy - Chinese alchemy
• Alchemy - Indian alchemy
• Alchemy - Alchemy in the Greek world
• Alchemy - Alchemy in the Roman Empire
• Alchemy - Alchemy in the Islamic world
• Alchemy - Alchemy in Medieval Europe
• Alchemy - Alchemy in the Modern Age and Renaissance
• Alchemy - The decline of Western alchemy
• Alchemy - Modern 'alchemy'
• Alchemy - Alchemy in art and entertainment
• Alchemy - Literature
• Alchemy - Music
• Alchemy - Other alchemical pages
• Alchemy - Related and alternative philosophies
• Alchemy - Scientific connections
• Alchemy - Substances of the alchemists
• Alchemy - Other resources

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Albert Abraham Michelson, (pronunciation anglicized as "Michael-son", December 19, 1852 - May 9, 1931), was a Prussian-born American physicist known for his work on the measurement of the speed of light, and especially for the Michelson-Morley experiment. In 1907 he received a Nobel prize for physics, the first American to receive the Nobel Prize in the sciences. Albert Abraham Michelson - Life. Michelson was born in Strzelno, Poland (then Strelno, Provinz Posen Kingdom of Prussia) in 1852, the son of a Jew ...

Including:

• Albert Abraham Michelson - Life
• Albert Abraham Michelson - Speed of light
• Albert Abraham Michelson - Early measurements
• Albert Abraham Michelson - Mount Wilson and Lookout Mountain 1926
• Albert Abraham Michelson - Michelson Pease & Pearson 1932
• Albert Abraham Michelson - Interferometry
• Albert Abraham Michelson - Astronomical interferometry
• Albert Abraham Michelson - Reference in Bonanza television series
• Albert Abraham Michelson - Electronic books

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In meteorology, visibility is a measure of the distance that can be seen clearly at any given time. It is important to all forms of traffic: roads, sailing and aviation. Meteorological visibility refers to transparency of air: in dark, meteorological visibility is still the same as in the same air in daylight. For aviation, several subclasses such as Runway Visual Range (RVR) have been defined. In extremely clean air in Arctic or mountainous areas, the visibility can be up to 70 to 100 km. However, visibility is often reduced s ...

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In mathematics, the Airy function Ai(x) is a special function, i.e., a function that appears so frequently that it deserves its own name. It is named after the British astronomer George Biddell Airy. The function Ai(x) and the related function Bi(x), which is also called an Airy function, are solutions to the differential equation y'' − xy = 0. This is the simplest second-order linear differential equation with a turning point (a point ...

Including:

• Airy function - Definitions
• Airy function - Properties
• Airy function - Asymptotic formulas
• Airy function - Complex arguments
• Airy function - Relation to other special functions
• Airy function - History

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Anti-reflective or antireflection (AR) coatings are a type of optical coating applied to lenses and other devices to reduce reflection from optical surfaces. This often improves the efficiency of the system; this is especially important if the light wasted by reflections is difficult to obtain, i.e. from a large telescope, an obstacle on a dark roadway, or an intricate optics experiment. They also have qualitative benefits like making the eyes of a glasses-wea ...

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For broader historical context, see 1260s and 13th century. 1267 - Events. 1267 - Europe. King Afonso III of Portugal and King Alfonso X of Castile sign a treaty determining the southern border between Portugal and Spain as the Guadiana River, a border that remains to this day. The Second Barons' War in England ends, as the rebels and King Henry III of England agree to peace terms as laid out in the Dictum of Kenilworth. King Henry III of England ...

Including:

• 1267 - Events
• 1267 - Europe
• 1267 - Asia and Africa
• 1267 - Births
• 1267 - Deaths

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In general, a threshold is a fixed location or value where an abrupt change is observed. It may also have the following meanings: In architecture, a threshold is a strip of wood, metal or stone located on the floor in a doorway following the line of division between the two spaces linked by the doorway. In aviation, a threshold is the end of a runway over which an airplane first passes when landing. In Biology, an action potential is initiated if the membrane potential ...

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In most modern usages of the word spectrum, there is a unifying theme of a variety of possible cases between extremes at either end. Older usages were not necessarily on that same unifying theme, but nonetheless led to the modern ones through a sequence of events set out below. Some modern usages in mathematics evolved out of that unifying theme but may be difficult to recognize as fitting into it. Spectrum - Origins. Originally a spectrum was what is now called a spectre, i.e., a phantom or ...

Including:

• Spectrum - Origins
• Spectrum - Modern 17th through 21st centuries meaning in the physical sciences

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Roger Bacon (c. 1214 – 1294), also known as Doctor Mirabilis (Latin: "astounding teacher"), was one of the most famous Franciscan friars of his time. He was an English philosopher who placed considerable emphasis on empiricism, and has been presented as one of the earliest advocates of the modern scientific method; though later studies have emphasized his reliance on occult and alchemical traditions. He was intimately acquainted with the philosophical and scientific insights of the Arab world, one of the most advanced civiliz ...

Including:

• Roger Bacon - Early life
• Roger Bacon - Life and works
• Roger Bacon - In fiction
• Roger Bacon - See Also
• Roger Bacon - External link

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X is the twenty-fourth letter of the Latin alphabet. Its name in English is ex (/ɛks/). In phonetics, x is the IPA and X-SAMPA symbol for the voiceless velar fricative (IPA is used for pronunciation throughout this article). The consonant cluster /ks/ was in Ancient Greece written as Chi 'Χ' (Western Greek) or Xi 'Ξ' (Eastern Greek). In the end, Chi was standardized as Including:

• X - Codes for computing
• X - Meanings for X

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Wake turbulence, also known as "jetwash", is turbulence that forms behind an aircraft as it passes through the air. This turbulence can be especially hazardous during the landing and take off phases of flight, where an aircraft's proximity to the ground makes a timely recovery from turbulence-induced problems unlikely. Wingtip vortices make up the primary and most dangerous component of wake turbulence, but normal wake effects are also an important part. Wake turbulence - Special Hazards associated with wake turbulenceIncluding:

• Wake turbulence - Special Hazards associated with wake turbulence
• Wake turbulence - Hazard avoidance
• Wake turbulence - Examples of accidents/incidents due to wake turbulence
• Wake turbulence - Measurement

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