1.
Mount Hood
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Mount Hood, called Wyeast by the Multnomah tribe, is a potentially active stratovolcano in the Cascade Volcanic Arc of northern Oregon. It was formed by a zone on the Pacific coast. It is located about 50 miles east-southeast of Portland, on the border between Clackamas and Hood River counties, in addition to being Oregons highest mountain, it is one of the loftiest mountains in the nation based on its prominence. The height assigned to Mount Hoods snow-covered peak has varied over its history, the peak is home to 12 named glaciers and snowfields. It is the highest point in Oregon and the fourth highest in the Cascade Range, Mount Hood is considered the Oregon volcano most likely to erupt, though based on its history, an explosive eruption is unlikely. Timberline Lodge is a National Historic Landmark located on the flank of Mount Hood just below Palmer Glacier. The mountain has six ski areas, Timberline, Mount Hood Meadows, Ski Bowl, Cooper Spur, Snow Bunny and they total over 4,600 acres of skiable terrain, Timberline offers the only year-round lift-served skiing in North America. The most northwestern pass around the mountain is called Lolo Pass, native Americans crossed the pass while traveling between the Willamette Valley and Celilo Falls. The Multnomah name for Mount Hood was Wyeast, in one version of the legend, the two sons of the Great Spirit Sahale fell in love with the beautiful maiden Loowit, who could not decide which to choose. The two braves, Wyeast and Pahto, burned forests and villages in their battle over her, Sahale became enraged and smote the three lovers. Seeing what he had done, he erected three mountain peaks to mark where each fell and he made beautiful Mount St. Helens for Loowit, proud and erect Mount Hood for Wyeast, and the somber Mount Adams for the mourning Pahto. There are other versions of the legend, in another telling, Wyeast battles Pahto for the fair La-wa-la-clough. Or again Wyeast, the chief of the Multnomah tribe, competed with the chief of the Klickitat tribe and their great anger led to their transformation into volcanoes. Their battle is said to have destroyed the Bridge of the Gods, the mountain was given its present name on October 29,1792, by Lt. William Broughton, a member of Captain George Vancouvers discovery expedition. Lt. and seemed to announce a termination to the river, Lt. Broughton named the mountain after Lord Hood, a British Admiral at the Battle of the Chesapeake. Lewis and Clark spotted the mountain on October 18,1805 and it is at this time topped with snow. We called this the Falls Mountain, or Timm Mountain, Timm was the native name for Celilo Falls. Clark later noted that it was also Vancouvers Mount Hood, two French explorers from the Hudsons Bay Company may have traveled into the Dog River area east of Mount Hood in 1818
2.
Optics
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Optics is the branch of physics which involves 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 using the classical 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, physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that waves were in fact electromagnetic radiation. Some phenomena depend on the fact that light has both wave-like and particle-like properties, explanation of these effects requires quantum mechanics. When considering lights particle-like properties, the light is modelled as a collection of particles called photons, quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. Optics began with the development of lenses by the ancient Egyptians and Mesopotamians, the earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrian lenses such as the Layard/Nimrud lens. The ancient Romans and Greeks filled glass spheres with water to make lenses, the word optics comes from the ancient Greek word ὀπτική, meaning appearance, look. Greek philosophy on optics broke down into two opposing theories on how vision worked, the theory and the emission theory. The intro-mission approach saw vision as coming from objects casting off copies of themselves that were captured by the eye, plato first articulated the emission theory, the idea that visual perception is accomplished by rays emitted by the eyes. He also commented on the parity reversal of mirrors in Timaeus, some hundred years later, Euclid wrote a treatise entitled Optics where he linked vision to geometry, creating geometrical optics. Ptolemy, in his treatise Optics, held a theory of vision, the rays from the eye formed a cone, the vertex being within the eye. The rays were sensitive, and conveyed back to the observer’s intellect about the distance. He summarised much of Euclid and went on to describe a way to measure the angle of refraction, during the Middle Ages, Greek ideas about optics were resurrected and extended by writers in the Muslim world
3.
Specular reflection
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Specular reflection, also known as regular reflection is the mirror-like reflection of waves, such as light, from a surface. In this process, each incident ray is reflected, with the reflected ray having the same angle to the normal as the incident ray. The result is that an image reflected by the surface is reproduced in mirror-like fashion, the law of reflection states that for each incident ray the angle of incidence equals the angle of reflection, and the incident, normal, and reflected directions are coplanar. This behavior was first described by Hero of Alexandria, when light hits a surface, there are three possible outcomes. Light may be absorbed by the material, light may be transmitted through the surface, or light may be reflected back. Materials often show some mix of these behaviors, with the proportion of light that goes to each depending on the properties of the material, the wavelength of the light, and the angle of incidence. For most interfaces between materials, the fraction of the light that is reflected increases with increasing angle of incidence θ i, reflected light can be divided into two sub-types, specular reflection and diffuse reflection. Specular reflection reflects all light at the angle, whereas diffuse reflection reflects in a broad range of directions. An example of the distinction between specular and diffuse reflection would be glossy and matte paints, matte paints have almost exclusively diffuse reflection, while glossy paints have both specular and diffuse reflection. A surface built from a powder, such as plaster, can be a nearly perfect diffuser. The reflecting material of mirrors is usually aluminum or silver, the law of reflection describes the angle of reflected light, the angle of incident light is the same as the angle of the reflected light. If a mirror becomes very small compared to the wavelength, the law of reflection no longer holds, the law of reflection can also be equivalently expressed using linear algebra. The direction of a ray is determined by the vector of incidence. Different authors may define the incident and reflection directions with different signs, reflectivity is the ratio of the power of the reflected wave to that of the incident wave. It is a function of the wavelength of radiation, and is related to the index of the material as expressed by Fresnels equations. The polarization of the light depends on the symmetry of the arrangement of the incident probing light with respect to the absorbing transitions dipole moments in the material. Measurement of specular reflection is performed with normal or varying incidence reflection spectrophotometers using a scanning variable-wavelength light source, lower quality measurements using a glossmeter quantify the glossy appearance of a surface in gloss units. Specular reflection from a dielectric such as water can affect polarization, the image in a flat mirror has these features, It is the same distance behind the mirror as the object is in front
4.
Mirror
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This is different from other light-reflecting objects that do not preserve much of the original wave signal other than color and diffuse reflected light. The most familiar type of mirror is the mirror, which has a flat screen surface. Curved mirrors are used, to produce magnified or diminished images or focus light or simply distort the reflected image. Mirrors are commonly used for personal grooming or admiring oneself, decoration, Mirrors are also used in scientific apparatus such as telescopes and lasers, cameras, and industrial machinery. Most mirrors are designed for light, however, mirrors designed for other wavelengths of electromagnetic radiation are also used. The first mirrors used by people were most likely pools of dark, still water, the requirements for making a good mirror are a surface with a very high degree of flatness, and a surface roughness smaller than the wavelength of the light. The earliest manufactured mirrors were pieces of polished stone such as obsidian, examples of obsidian mirrors found in Anatolia have been dated to around 6000 BC. Mirrors of polished copper were crafted in Mesopotamia from 4000 BC, polished stone mirrors from Central and South America date from around 2000 BC onwards. In China, bronze mirrors were manufactured from around 2000 BC, some of the earliest bronze, Mirrors made of other metal mixtures such as copper and tin speculum metal may have also been produced in China and India. Mirrors of speculum metal or any precious metal were hard to produce and were owned by the wealthy. Stone mirrors often had poor reflectivity compared to metals, yet metals scratch or tarnish easily, depending upon the color, both often yielded reflections with poor color rendering. The poor image quality of ancient mirrors explains 1 Corinthians 13s reference to seeing as in a mirror, glass was a desirable material for mirrors. Because the surface of glass is smooth, it produces reflections with very little blur. In addition, glass is very hard and scratch resistant, however, glass by itself has little reflectivity, so people began coating it with metals to increase the reflectivity. According to Pliny, the people of Sidon developed a technique for creating crude mirrors by coating glass with molten lead. Glass mirrors backed with gold leaf are mentioned by Pliny in his Natural History and these circular mirrors were typically small, from only a fraction of an inch to as much as eight inches in diameter. These small mirrors produced distorted images, yet were prized objects of high value and these ancient glass mirrors were very thin, thus very fragile, because the glass needed to be extremely thin to prevent cracking when coated with a hot, molten metal. Due to the quality, high cost, and small size of these ancient glass mirrors
5.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
6.
Geometry
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Geometry is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space. A mathematician who works in the field of geometry is called a geometer, Geometry arose independently in a number of early cultures as a practical way for dealing with lengths, areas, and volumes. Geometry began to see elements of mathematical science emerging in the West as early as the 6th century BC. By the 3rd century BC, geometry was put into a form by Euclid, whose treatment, Euclids Elements. Geometry arose independently in India, with texts providing rules for geometric constructions appearing as early as the 3rd century BC, islamic scientists preserved Greek ideas and expanded on them during the Middle Ages. By the early 17th century, geometry had been put on a solid footing by mathematicians such as René Descartes. Since then, and into modern times, geometry has expanded into non-Euclidean geometry and manifolds, while geometry has evolved significantly throughout the years, there are some general concepts that are more or less fundamental to geometry. These include the concepts of points, lines, planes, surfaces, angles, contemporary geometry has many subfields, Euclidean geometry is geometry in its classical sense. The mandatory educational curriculum of the majority of nations includes the study of points, lines, planes, angles, triangles, congruence, similarity, solid figures, circles, Euclidean geometry also has applications in computer science, crystallography, and various branches of modern mathematics. Differential geometry uses techniques of calculus and linear algebra to problems in geometry. It has applications in physics, including in general relativity, topology is the field concerned with the properties of geometric objects that are unchanged by continuous mappings. In practice, this often means dealing with large-scale properties of spaces, convex geometry investigates convex shapes in the Euclidean space and its more abstract analogues, often using techniques of real analysis. It has close connections to convex analysis, optimization and functional analysis, algebraic geometry studies geometry through the use of multivariate polynomials and other algebraic techniques. It has applications in areas, including cryptography and string theory. Discrete geometry is concerned mainly with questions of relative position of simple objects, such as points. It shares many methods and principles with combinatorics, Geometry has applications to many fields, including art, architecture, physics, as well as to other branches of mathematics. The earliest recorded beginnings of geometry can be traced to ancient Mesopotamia, the earliest known texts on geometry are the Egyptian Rhind Papyrus and Moscow Papyrus, the Babylonian clay tablets such as Plimpton 322. For example, the Moscow Papyrus gives a formula for calculating the volume of a truncated pyramid, later clay tablets demonstrate that Babylonian astronomers implemented trapezoid procedures for computing Jupiters position and motion within time-velocity space
7.
Reflection symmetry
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Reflection symmetry, line symmetry, mirror symmetry, mirror-image symmetry, is symmetry with respect to reflection. That is, a figure which does not change upon undergoing a reflection has reflectional symmetry, in 2D there is a line/axis of symmetry, in 3D a plane of symmetry. An object or figure which is indistinguishable from its image is called mirror symmetric. The set of operations that preserve a property of the object form a group. Two objects are symmetric to each other with respect to a group of operations if one is obtained from the other by some of the operations. Another way to think about the function is that if the shape were to be folded in half over the axis. Thus a square has four axes of symmetry, because there are four different ways to fold it and have the edges all match, a circle has infinitely many axes of symmetry. Triangles with reflection symmetry are isosceles, quadrilaterals with reflection symmetry are kites, deltoids, rhombuses, and isosceles trapezoids. All even-sided polygons have two simple reflective forms, one with lines of reflections through vertices, and one through edges, for an arbitrary shape, the axiality of the shape measures how close it is to being bilaterally symmetric. It equals 1 for shapes with reflection symmetry, and between 2/3 and 1 for any convex shape, for each line or plane of reflection, the symmetry group is isomorphic with Cs, one of the three types of order two, hence algebraically C2. The fundamental domain is a half-plane or half-space, in certain contexts there is rotational as well as reflection symmetry. Then mirror-image symmetry is equivalent to inversion symmetry, in contexts in modern physics the term parity or P-symmetry is used for both. For more general types of reflection there are more general types of reflection symmetry. For example, with respect to a non-isometric affine involution with respect to circle inversion, most animals are bilaterally symmetric, likely because this supports forward movement and streamlining. Mirror symmetry is used in architecture, as in the facade of Santa Maria Novella. It is also found in the design of ancient structures such as Stonehenge, Symmetry was a core element in some styles of architecture, such as Palladianism. Patterns in nature Point reflection symmetry Stewart, Ian, weidenfeld & Nicolson. is potty Weyl, Hermann. Mapping with symmetry - source in Delphi Reflection Symmetry Examples from Math Is Fun
8.
Virtual image
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In optics, a virtual image is an image formed when the outgoing rays from a point on an object always diverge. The image appears to be located at the point of apparent divergence, because the rays never really converge, a virtual image cannot be projected onto a screen. In diagrams of systems, virtual rays are conventionally represented by dotted lines. Virtual images are located by tracing the rays that emerge from an optical device backward to a perceived point of origin. In contrast, an image is one that is formed when the outgoing rays forms a point converging at a real location. Real images can be projected onto a diffuse reflecting screen, but a screen is not necessary for the image to form, a plane mirror forms a virtual image positioned behind the mirror. Although the rays of light seem to come from behind the mirror, the image in a plane mirror is not magnified and appears to be as far behind the mirror as the object is in front of the mirror. A diverging lens or a convex mirror forms a virtual image, such an image is reduced in size when compared to the original object. A converging lens or a mirror is also capable of producing a virtual image if the object is within the focal length. Such an image will be magnified, in contrast, an object placed in front of a converging lens or concave mirror at a position beyond the focal length produces a real image. Such an image may be magnified or reduced depending on the position of the object
9.
Reflection (mathematics)
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In mathematics, a reflection is a mapping from a Euclidean space to itself that is an isometry with a hyperplane as a set of fixed points, this set is called the axis or plane of reflection. The image of a figure by a reflection is its image in the axis or plane of reflection. For example the image of the small Latin letter p for a reflection with respect to a vertical axis would look like q. Its image by reflection in a horizontal axis would look like b, a reflection is an involution, when applied twice in succession, every point returns to its original location, and every geometrical object is restored to its original state. The term reflection is used for a larger class of mappings from a Euclidean space to itself. Such isometries have a set of fixed points that is an affine subspace, for instance a reflection through a point is an involutive isometry with just one fixed point, the image of the letter p under it would look like a d. This operation is known as a central inversion, and exhibits Euclidean space as a symmetric space. In a Euclidean vector space, the reflection in the point situated at the origin is the same as vector negation, other examples include reflections in a line in three-dimensional space. Typically, however, unqualified use of the term reflection means reflection in a hyperplane, a figure that does not change upon undergoing a reflection is said to have reflectional symmetry. Some mathematicians use flip as a synonym for reflection, in a plane geometry, to find the reflection of a point drop a perpendicular from the point to the line used for reflection, and extend it the same distance on the other side. To find the reflection of a figure, reflect each point in the figure, step 2, construct circles centered at A′ and B′ having radius r. P and Q will be the points of intersection of two circles. Point Q is then the reflection of point P through line AB, the matrix for a reflection is orthogonal with determinant −1 and eigenvalues −1,1,1. The product of two matrices is a special orthogonal matrix that represents a rotation. Every rotation is the result of reflecting in an number of reflections in hyperplanes through the origin. Thus reflections generate the group, and this result is known as the Cartan–Dieudonné theorem. Similarly the Euclidean group, which consists of all isometries of Euclidean space, is generated by reflections in affine hyperplanes, in general, a group generated by reflections in affine hyperplanes is known as a reflection group. The finite groups generated in this way are examples of Coxeter groups, note that the second term in the above equation is just twice the vector projection of v onto a
10.
Plane mirror
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A plane mirror is a mirror with a flat reflective surface. For light rays striking a plane mirror, the angle of reflection equals the angle of incidence, the angle of incidence is the angle between the incident ray and the surface normal. A plane mirror makes an image of objects in front of it, a straight line drawn from part of an object to the corresponding part of its image makes a right angle with, and is bisected by, the surface of the plane mirror. The image formed by a mirror is always virtual, upright. A virtual image is a copy of an object formed at the location from which the rays appear to come. However, the image is a mirror image of the object. If a person is reflected in a mirror, the image of his right hand appears to be the left hand of the image. Plane mirrors are the type of mirror for which a real object always produces an image that is virtual, erect. Virtual objects produce real images, however, the focal length of a plane mirror is infinity, its optical power is zero. The reflecting surface reflects most of the light striking it as long as the surface a remains uncontaminated by tarnishing or oxidation, most modern plane mirrors are designed with a thin piece of plate glass that protects and strengthens the mirror surface and helps prevent tarnishing. Historically, mirrors were simply flat pieces of polished copper, obsidian, brass, mirrors made from liquid also exist, as the elements gallium and mercury are both highly reflective in their liquid state. Mathematically, a mirror can be considered to be the limit of either a concave or a convex spherical curved mirror as the radius. Geometrical optics Specular reflection Chinese magic mirror
11.
Parity (physics)
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In quantum mechanics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it is often described by the simultaneous flip in the sign of all three spatial coordinates, P, ↦. It can also be thought of as a test for chirality of a physical phenomenon, a parity transformation on something achiral, on the other hand, can be viewed as an identity transformation. All fundamental interactions of particles, with the exception of the weak interaction, are symmetric under parity. The weak interaction is chiral and thus provides a means for probing chirality in physics, in interactions that are symmetric under parity, such as electromagnetism in atomic and molecular physics, parity serves as a powerful controlling principle underlying quantum transitions. A matrix representation of P has determinant equal to −1, and hence is distinct from a rotation, in a two-dimensional plane, a simultaneous flip of all coordinates in sign is not a parity transformation, it is the same as a 180°-rotation. Under rotations, classical geometrical objects can be classified into scalars, vectors, in classical physics, physical configurations need to transform under representations of every symmetry group. Quantum theory predicts that states in a Hilbert space do not need to transform under representations of the group of rotations, the projective representations of any group are isomorphic to the ordinary representations of a central extension of the group. For example, projective representations of the 3-dimensional rotation group, which is the orthogonal group SO, are ordinary representations of the special unitary group SU. Projective representations of the group that are not representations are called spinors. If one adds to this a classification by parity, these can be extended, for example, vectors and axial vectors which both transform as vectors under rotation. One can define reflections such as V x, ↦, which also have negative determinant, then, combining them with rotations one can recover the particular parity transformation defined earlier. The first parity transformation given does not work in an number of dimensions, though. In odd number of only the latter example of a parity transformation can be used. Parity forms the abelian group Z2 due to the relation P2 =1, all Abelian groups have only one-dimensional irreducible representations. For Z2, there are two representations, one is even under parity, the other is odd. These are useful in quantum mechanics, newtons equation of motion F = ma equates two vectors, and hence is invariant under parity. The law of gravity also involves only vectors and is also, therefore, however, angular momentum L is an axial vector, L = r × p, P = × = L
12.
Three-dimensional space
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Three-dimensional space is a geometric setting in which three values are required to determine the position of an element. This is the meaning of the term dimension. In physics and mathematics, a sequence of n numbers can be understood as a location in n-dimensional space, when n =3, the set of all such locations is called three-dimensional Euclidean space. It is commonly represented by the symbol ℝ3 and this serves as a three-parameter model of the physical universe in which all known matter exists. However, this space is one example of a large variety of spaces in three dimensions called 3-manifolds. Furthermore, in case, these three values can be labeled by any combination of three chosen from the terms width, height, depth, and breadth. In mathematics, analytic geometry describes every point in space by means of three coordinates. Three coordinate axes are given, each perpendicular to the two at the origin, the point at which they cross. They are usually labeled x, y, and z, below are images of the above-mentioned systems. Two distinct points determine a line. Three distinct points are either collinear or determine a unique plane, four distinct points can either be collinear, coplanar or determine the entire space. Two distinct lines can intersect, be parallel or be skew. Two parallel lines, or two intersecting lines, lie in a plane, so skew lines are lines that do not meet. Two distinct planes can either meet in a line or are parallel. Three distinct planes, no pair of which are parallel, can meet in a common line. In the last case, the three lines of intersection of each pair of planes are mutually parallel, a line can lie in a given plane, intersect that plane in a unique point or be parallel to the plane. In the last case, there will be lines in the plane that are parallel to the given line, a hyperplane is a subspace of one dimension less than the dimension of the full space. The hyperplanes of a space are the two-dimensional subspaces, that is
13.
Transparency and translucency
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In the field of optics, transparency is the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale, the photons can be said to follow Snells Law, in other words, a translucent medium allows the transport of light while a transparent medium not only allows the transport of light but allows for image formation. The opposite property of translucency is opacity, transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. When light encounters a material, it can interact with it in different ways. These interactions depend on the wavelength of the light and the nature of the material, photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as glass and clean water, transmit much of the light that falls on them and reflect little of it. Many liquids and aqueous solutions are highly transparent, absence of structural defects and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials which do not transmit light are called opaque, many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of light frequencies. They absorb certain portions of the spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation and this is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the mechanisms of absorption. Transparency can provide almost perfect camouflage for animals able to achieve it and this is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent, at the atomic or molecular level, physical absorption in the infrared portion of the spectrum depends on the frequencies of atomic or molecular vibrations or chemical bonds, and on selection rules. Nitrogen and oxygen are not greenhouse gases because there is no absorption because there is no molecular dipole moment. With regard to the scattering of light, the most critical factor is the scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include, Crystalline structure, whether or not the atoms or molecules exhibit the long-range order evidenced in crystalline solids, glassy structure, scattering centers include fluctuations in density or composition. Microstructure, scattering centers include internal surfaces such as boundaries, crystallographic defects
14.
Geometrical optics
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Geometrical optics, or ray optics, describes light propagation in terms of rays. The ray in geometric optics is an abstraction, or instrument, Geometrical optics does not account for certain optical effects such as diffraction and interference. This simplification is useful in practice, it is an excellent approximation when the wavelength is compared to the size of structures with which the light interacts. The techniques are useful in describing geometrical aspects of imaging, including optical aberrations. A light ray is a line or curve that is perpendicular to the lights wavefronts, Geometrical optics is often simplified by making the paraxial approximation, or small angle approximation. The mathematical behavior then becomes linear, allowing optical components and systems to be described by simple matrices, glossy surfaces such as mirrors reflect light in a simple, predictable way. This allows for production of reflected images that can be associated with an actual or extrapolated location in space. With such surfaces, the direction of the ray is determined by the angle the incident ray makes with the surface normal. The incident and reflected rays lie in a plane. This is known as the Law of Reflection, for flat mirrors, the law of reflection implies that images of objects are upright and the same distance behind the mirror as the objects are in front of the mirror. The image size is the same as the object size, the law also implies that mirror images are parity inverted, which is perceived as a left-right inversion. Mirrors with curved surfaces can be modeled by ray tracing and using the law of reflection at each point on the surface, for mirrors with parabolic surfaces, parallel rays incident on the mirror produce reflected rays that converge at a common focus. Other curved surfaces may also focus light, but with due to the diverging shape causing the focus to be smeared out in space. In particular, spherical mirrors exhibit spherical aberration, curved mirrors can form images with magnification greater than or less than one, and the image can be upright or inverted. An upright image formed by reflection in a mirror is always virtual, while an image is real. Refraction occurs when light travels through an area of space that has a index of refraction. The simplest case of refraction occurs when there is an interface between a uniform medium with index of refraction n 1 and another medium with index of refraction n 2 and this phenomenon is called total internal reflection and allows for fiber optics technology. As light signals travel down a fiber cable, they undergo total internal reflection allowing for essentially no light lost over the length of the cable
15.
Enantiomer
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A single chiral atom or similar structural feature in a compound causes that compound to have two possible structures which are non-superposable, each a mirror image of the other. Each member of the pair is termed an enantiomorph, the property is termed enantiomerism. The presence of multiple features in a given compound increases the number of geometric forms possible. Enantiopure compounds refer to samples having, within the limits of detection and they are sometimes called optical isomers for this reason. Enantiomer members often have different chemical reactions with other enantiomer substances, since many biological molecules are enantiomers, there is sometimes a marked difference in the effects of two enantiomers on biological organisms. Owing to this discovery, drugs composed of one enantiomer can be developed to enhance the pharmacological efficacy. An example is eszopiclone, which is enantiopure and therefore administered in doses that are exactly 1/2 of the older, in the case of eszopiclone, the S enantiomer is responsible for all the desired effects, while the other enantiomer seems to be inactive. A dose of 2 mg of zopiclone must be administered to produce the therapeutic effect as 1 mg of eszopiclone. In chemical synthesis of enantiomeric substances, non-enantiomeric precursors inevitably produce racemic mixtures, in the absence of an effective enantiomeric environment, separation of a racemic mixture into its enantiomeric components is impossible. The R/S system is an important nomenclature system for denoting distinct enantiomers, another system is based on prefix notation for optical activity, - and - or d- and l-. The Latin for left and right is laevus and dexter, respectively, left and right have always had moral connotations, and the Latin words for these are sinister and rectus. The English word right is a cognate of rectus and this is the origin of the D, L and S, R notations, and the employment of prefixes levo- and dextro- in common names. Most compounds that one or more asymmetric carbon atoms show enantiomerism. There are a few compounds that do have asymmetric carbon atoms. An example of such an enantiomer is the sedative thalidomide, which was sold in a number of countries across the world from 1957 until 1961 and it was withdrawn from the market when it was found to cause of birth defects. One enantiomer caused the desirable effects, while the other, unavoidably present in equal quantities. The herbicide mecoprop is a mixture, with the --enantiomer possessing the herbicidal activity. Another example is the antidepressant drugs escitalopram and citalopram, citalopram is a racemate, escitalopram is a pure enantiomer
16.
Chirality (chemistry)
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Chirality /kaɪˈrælɪti/ is a geometric property of some molecules and ions. A chiral molecule/ion is non-superposable on its mirror image, the presence of an asymmetric carbon center is one of several structural features that induce chirality in organic and inorganic molecules. The term chirality is derived from the Greek word for hand, the mirror images of a chiral molecule/ion are called enantiomers or optical isomers. Individual enantiomers are often designated as either right- or left-handed, Chirality is an essential consideration when discussing the stereochemistry in organic and inorganic chemistry. The concept is of practical importance because most biomolecules and pharmaceuticals are chiral. Chirality is based on molecular symmetry elements, specifically, a chiral compound can contain no improper axis of rotation, which includes planes of symmetry and inversion center. Chiral molecules are always dissymmetric but not always asymmetric, in general, chiral molecules have point chirality at a single stereogenic atom, which has four different substituents. The two enantiomers of such compounds are said to have different absolute configurations at this center, the stereogenic atom is usually carbon, as in many biological molecules. However chirality can exist in any atom, including metals, phosphorus, Chiral nitrogen is equally possible, although the effects of nitrogen inversion can make many of these compounds impossible to isolate. While the presence of a stereogenic atom describes the great majority of cases, for instance it is not necessary for the chiral substance to have a stereogenic atom. Examples include 1-bromo-1-chloro-1-fluoroadamantane, methylethylphenyltetrahedrane, certain calixarenes and fullerenes, which have inherent chirality, the C2-symmetric species 1, 1-bi-2-naphthol,1, 3-dichloro-allene have axial chirality. -cyclooctene and many ferrocenes have planar chirality, when the optical rotation for an enantiomer is too low for practical measurement, the species is said to exhibit cryptochirality. Even isotopic differences must be considered when examining chirality, illustrative is the derivative of benzyl alcohol PhCHDOH is chiral. The S enantiomer has D = +0. 715°, many biologically active molecules are chiral, including the naturally occurring amino acids and sugars. In biological systems, most of these compounds are of the chirality, most amino acids are levorotatory. Typical naturally occurring proteins, made of L amino acids, are known as left-handed proteins, d-amino acids are very rare in nature and have only been found in small peptides attached to bacteria cell walls. The origin of this homochirality in biology is the subject of much debate, however, there is some suggestion that early amino acids could have formed in comet dust. Enzymes, which are chiral, often distinguish between the two enantiomers of a chiral substrate, one could imagine an enzyme as having a glove-like cavity that binds a substrate
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Chirality (mathematics)
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In geometry, a figure is chiral if it is not identical to its mirror image, or, more precisely, if it cannot be mapped to its mirror image by rotations and translations alone. An object that is not chiral is said to be achiral, in 3 dimensions, not all achiral objects have a mirror plane. For example, a 3-dimensional object with inversion centre as its only nontrivial symmetry operation is achiral but has no mirror plane, a chiral object and its mirror image are said to be enantiomorphs. The word chirality is derived from the Greek χείρ, the hand, the most familiar chiral object, a non-chiral figure is called achiral or amphichiral. Some chiral three-dimensional objects, such as the helix, can be assigned a right or left handedness, many other familiar objects exhibit the same chiral symmetry of the human body, such as gloves and shoes. A right shoe is different from a left shoe only for being mirror images of each other, in contrast thin gloves may not be considered chiral if you can wear them inside-out. The J, L, S and Z-shaped tetrominoes of the video game Tetris also exhibit chirality. Individually they contain no mirror symmetry in the plane, a figure is achiral if and only if its symmetry group contains at least one orientation-reversing isometry. In three dimensions, every figure that possesses a plane of symmetry S1, an inversion center of symmetry S2. Note, however, that there are achiral figures lacking both plane and center of symmetry, an example is the figure F0 = which is invariant under the orientation reversing isometry ↦ and thus achiral, but it has neither plane nor center of symmetry. The figure F1 = also is achiral as the origin is a center of symmetry, note also that achiral figures can have a center axis. In two dimensions, every figure which possesses an axis of symmetry is achiral, and it can be shown that every bounded achiral figure must have an axis of symmetry and its symmetry group is a frieze group generated by a single glide reflection. A knot is called if it can be continuously deformed into its mirror image. For example the unknot and the knot are achiral, whereas the trefoil knot is chiral. Chirality in Metric Spaces, Symmetry, Culture and Science 21, pp. 27–36 Chiral Polyhedra by Eric W. Weisstein, when Topology Meets Chemistry by Erica Flapan. Chiral manifold at the Manifold Atlas
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Normal (geometry)
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In geometry, a normal is an object such as a line or vector that is perpendicular to a given object. For example, in the case, the normal line to a curve at a given point is the line perpendicular to the tangent line to the curve at the point. In the three-dimensional case a normal, or simply normal. The word normal is used as an adjective, a line normal to a plane, the normal component of a force. The concept of normality generalizes to orthogonality, the concept has been generalized to differentiable manifolds of arbitrary dimension embedded in a Euclidean space. The normal vector space or normal space of a manifold at a point P is the set of the vectors which are orthogonal to the tangent space at P, in the case of differential curves, the curvature vector is a normal vector of special interest. For a convex polygon, a surface normal can be calculated as the cross product of two edges of the polygon. For a plane given by the equation a x + b y + c z + d =0, the vector is a normal. For a hyperplane in n+1 dimensions, given by the equation r = a 0 + α1 a 1 + ⋯ + α n a n, where a0 is a point on the hyperplane and ai for i =1. N are non-parallel vectors lying on the hyperplane, a normal to the hyperplane is any vector in the space of A where A is given by A =. That is, any vector orthogonal to all in-plane vectors is by definition a surface normal. If a surface S is parameterized by a system of coordinates x, with s and t real variables. For a surface S given explicitly as a function f of the independent variables x, y, the first one is obtaining its implicit form F = z − f =0, from which the normal follows readily as the gradient ∇ F. The second way of obtaining the normal follows directly from the gradient of the form, ∇ f, by inspection, ∇ F = k ^ − ∇ f. Note that this is equal to ∇ F = k ^ − ∂ f ∂ x i ^ − ∂ f ∂ y j ^, if a surface does not have a tangent plane at a point, it does not have a normal at that point either. For example, a cone does not have a normal at its tip nor does it have a normal along the edge of its base, however, the normal to the cone is defined almost everywhere. In general, it is possible to define a normal almost everywhere for a surface that is Lipschitz continuous, a normal to a surface does not have a unique direction, the vector pointing in the opposite direction of a surface normal is also a surface normal. For an oriented surface, the normal is usually determined by the right-hand rule
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Binocular vision
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Binocular vision is vision in which creatures having two eyes use them together. The word binocular comes from two Latin roots, bini for double, and oculus for eye, according to Fahle, having two eyes confers six advantages over having one. It gives a creature a spare eye in one is damaged. It gives a wider field of view and it can give stereopsis in which binocular disparity provided by the two eyes different positions on the head gives precise depth perception. This also allows a creature to break the camouflage of another creature and it allows the angles of the eyes lines of sight, relative to each other, and those lines relative to a particular object to be determined from the images in the two eyes. These properties are necessary for the third advantage and it allows a creature to see more of, or all of, an object behind an obstacle. It gives binocular summation in which the ability to detect faint objects is enhanced, other phenomena of binocular vision include utrocular discrimination, eye dominance, allelotropia, binocular fusion or singleness of vision, and binocular rivalry. Binocular vision helps with performance skills such as catching, grasping and it also allows humans to walk over and around obstacles at greater speed and with more assurance. Optometrists and/or Orthoptists are eyecare professionals who fix binocular vision problems, some animals, usually, but not always, prey animals, have their two eyes positioned on opposite sides of their heads to give the widest possible field of view. Examples include rabbits, buffaloes, and antelopes, in such animals, the eyes often move independently to increase the field of view. Even without moving their eyes, some birds have a 360-degree field of view, other animals that are not necessarily predators, such as fruit bats and a number of primates also have forward-facing eyes. These are usually animals that need fine depth discrimination/perception, for instance, binocular vision improves the ability to pick a chosen fruit or to find, the direction of a point relative to the head is called visual direction, or version. The angle between the line of sight of the two eyes when fixating a point is called the disparity, binocular parallax, or vergence demand. The relation between the position of the two eyes, version and vergence is described by Herings law of visual direction, in animals with forward-facing eyes, the eyes usually move together. Eye movements are either conjunctive, version eye movements, usually described by their type, or they are disjunctive, vergence eye movements. The relation between version and vergence eye movements in humans is described by Herings law of equal innervation, some animals use both of the above strategies. A starling, for example, has laterally placed eyes to cover a wide field of view, a remarkable example is the chameleon, whose eyes appear as if mounted on turrets, each moving independently of the other, up or down, left or right. Nevertheless, the chameleon can bring both of its eyes to bear on an object when it is hunting, showing vergence
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Conservation of energy
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In physics, the law of conservation of energy states that the total energy of an isolated system remains constant—it is said to be conserved over time. Energy can neither be created nor destroyed, rather, it transforms from one form to another, for instance, chemical energy can be converted to kinetic energy in the explosion of a stick of dynamite. A consequence of the law of conservation of energy is that a perpetual motion machine of the first kind cannot exist and that is to say, no system without an external energy supply can deliver an unlimited amount of energy to its surroundings. Ancient philosophers as far back as Thales of Miletus c.550 BCE had inklings of the conservation of some underlying substance of everything is made. However, there is no reason to identify this with what we know today as mass-energy. Empedocles wrote that in his system, composed of four roots, nothing comes to be or perishes, instead. In 1605, Simon Stevinus was able to solve a number of problems in statics based on the principle that perpetual motion was impossible. Essentially, he pointed out that the height a moving body rises is equal to the height from which it falls, and used this observation to infer the idea of inertia. The remarkable aspect of this observation is that the height that a moving body ascends to does not depend on the shape of the surface that the body is moving on. In 1669, Christian Huygens published his laws of collision, among the quantities he listed as being invariant before and after the collision of bodies were both the sum of their linear momentums as well as the sum of their kinetic energies. However, the difference between elastic and inelastic collision was not understood at the time and this led to the dispute among later researchers as to which of these conserved quantities was the more fundamental. In his Horologium Oscillatorium, he gave a much clearer statement regarding the height of ascent of a moving body, Huygens study of the dynamics of pendulum motion was based on a single principle, that the center of gravity of heavy objects cannot lift itself. The fact that energy is scalar, unlike linear momentum which is a vector. It was Leibniz during 1676–1689 who first attempted a mathematical formulation of the kind of energy which is connected with motion. Using Huygens work on collision, Leibniz noticed that in mechanical systems. He called this quantity the vis viva or living force of the system, the principle represents an accurate statement of the approximate conservation of kinetic energy in situations where there is no friction. Many physicists at that time, such as Newton, held that the conservation of momentum and it was later shown that both quantities are conserved simultaneously, given the proper conditions such as an elastic collision. In 1687, Isaac Newton published his Principia, which was organized around the concept of force and momentum
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Fire engine
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A fire engine is a vehicle designed primarily for firefighting operations. In addition, many fire departments/fire services often employ their vehicles for other uses including emergency medical services. The terms fire engine and fire truck are used interchangeably. The primary purposes of an engine include transporting firefighters to an incident scene, providing water with which to fight a fire. Many fire vehicles are based on standard vehicle models and they are normally fitted with audible and visual warnings, as well as communication equipment such as two-way radios and mobile computer technology. The standard fire engine is an apparatus designed primarily for firefighting operations, the tools carried on the fire engine will vary greatly based on many factors including the size of the department and what sort of terrain the department must handle. For example, departments located near bodies of water or rivers are likely to have some sort of water rescue equipment. Standard tools found on all fire engines include ladders, hydraulic rescue tools, floodlights, fire hose, fire extinguishers, self-contained breathing apparatus. The exact layout of what is carried on an engine is decided by the needs of the department, some fire engines have a fixed deluge gun, also known as a master stream, which directs a heavy stream of water to wherever the operator points it. An additional feature of engines are their preconnected hose lines, commonly referred to as preconnects, the preconnects are attached to the engines onboard water supply and allow firefighters to quickly mount an aggressive attack on the fire as soon as they arrive on scene. The name is derived from the fact that the ladder is mounted on a turntable on the back of a truck chassis. To increase its length, the ladder is telescopic, modern telescopic ladders are either hydraulic or pneumatic. These mechanical features allow the use of ladders which are longer, sturdier and they may also have pre-attached hoses or other equipment. A ladder can also be mounted behind the cab and this is sometimes called mid-ship and the arrangement allows a lower travel height for the truck, and also can be more stable in certain conditions. In some cases, there may also be a monitor at the top of the ladder for ease of use, other appliances may simply have a track-way which will hold a manually-run hose reel securely, and prevent it from falling to the ground. In the United States, a truck, also known as a tractor-drawn aerial, tiller ladder. Unlike a commercial semi, the trailer and tractor are permanently combined and it has two drivers, with separate steering wheels for front and rear wheels. One of the features of the tiller-truck is its enhanced maneuverability
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Mirror writing
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It is sometimes used as an extremely primitive form of cipher. Some people are able to produce handwritten mirrored text, and Leonardo da Vinci wrote most of his notes in this way. Mirror writing calligraphy was popular in the Ottoman Empire, where it often carried mystical associations, research suggests that the ability to produce handwritten mirror writing is probably inherited and caused by atypical language organization in the brain. Half of the children of people with the ability inherit it, a higher proportion of left-handed people are better mirror writers than right-handed people, perhaps because it is more natural for a left-hander to write backwards. 15% of left-handed people have the language centres in both halves of their brain, the cerebral cortex and motor homunculus are affected by this, causing the person to be able to read and write backwards quite naturally. This hypothesis was proposed because these affect an neural mechanism that controls the higher cerebral function of writing via the thalamus. Another study by the university discovered that damage was not the only cause. Leonardo da Vinci wrote most of his notes in mirror. The purpose of practice by Leonardo remains unknown, though several possible reasons have been suggested. For example, writing left handed from left to right would have been messy because the ink just put down would smear as his hand moved across it, Writing in reverse would prevent such smudging. Matteo Zaccolini may have written his original four volume treatise on optics, color, Mirror writing calligraphy was popular in the Ottoman Empire during the 18th and 19th centuries among the Bektashi order, where it often carried mystical associations. The origins of this mirror writing tradition may date to the period in rock inscriptions of the western Arabian peninsula. Peep show images shown in a zograscope have headers in Mirror writing, boustrophedon Ambigram Media related to Mirror writings at Wikimedia Commons Mirror Writing a genetic trait Jay A. Gottfried, kruba sundar, Feyza Sancar, Anjan chatterjee. Acquired mirror writing and reading, evidence for reflected graphemic representations, cS1 maint, Multiple names, authors list Mirror writing, neurological reflections on an unusual phenomenon
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Ambulance
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The word is often associated with road going emergency ambulances which form part of an emergency medical service, administering emergency care to those with acute medical problems. The term ambulance does, however, extend to a range of vehicles other than those with flashing warning lights. The term ambulance comes from the Latin word ambulare as meaning to walk or move about which is a reference to medical care where patients were moved by lifting or wheeling. The word originally meant a hospital, which follows an army in its movements. Ambulances were first used for transport in 1487 by the Spanish forces during the siege of Málaga by the Catholic Monarchs against the Emirate of Granada. During the American Civil War vehicles for conveying the wounded off the field of battle were called ambulance wagons, there are other types of ambulance, with the most common being the patient transport ambulance. These vehicles are not usually equipped with equipment, and are usually crewed by staff with fewer qualifications than the crew of emergency ambulances. Their purpose is simply to transport patients to, from or between places of treatment, in most countries, these are not equipped with flashing lights or sirens. In some jurisdictions there is a form of the ambulance used, that only carries one member of ambulance crew to the scene to provide care. In these cases a patient who requires transportation to hospital will require an ambulance to attend in addition to the first responder. The history of the ambulance begins in ancient times, with the use of carts to transport incurable patients by force, Ambulances were first used for emergency transport in 1487 by the Spanish, and civilian variants were put into operation during the 1830s. Advances in technology throughout the 19th and 20th centuries led to the modern self-powered ambulances, Ambulances can be grouped into types depending on whether or not they transport patients, and under what conditions. In some cases, ambulances may fulfil more than one function, Emergency ambulance – The most common type of ambulance, which provide care to patients with an acute illness or injury. These can be road-going vans, boats, helicopters, fixed-wing aircraft or even converted vehicles such as golf carts. Patient transport ambulance – A vehicle, which has the job of transporting patients to and these can be vans, buses or other vehicles. Response units may be backed up by an ambulance which can transport the patient, or may deal with the problem on scene. These can be a variety of vehicles, from standard cars, to modified vans, motorcycles, pedal cycles. These units can function as a vehicle for officers or supervisors, Fire & Rescue services in North America often staff EMTs or Paramedics to their apparatuses to provide medical care without the need to wait for an ambulance
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Rear-view mirror
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A rear-view mirror is a mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicles rear window. The rear-view mirror is augmented by one or more side-view mirrors, the Argus Dash Mirror, adjustable to any position to see the road behind, appeared in 1908. Earliest known rear-view mirror mounted on a racing vehicle appeared on Ray Harrouns Marmon race car at the inaugural Indianapolis 500 race in 1911, harroun himself claimed he got the idea from seeing a mirror used for a similar purpose on a horse-drawn vehicle in 1904. Harroun also claimed that the mirror vibrated constantly due to the brick surface. As many as 50 small children are killed by SUVs every year in the USA because the driver cannot see them in their rear-view mirrors, camera systems are usually mounted to the rear bumper or lower parts of the car, allowing for better rear visibility. Aftermarket secondary rear-view mirrors are available and they attach to the main rear-view mirror and are independently adjustable to view the back seat. This is useful to enable adults to children in the back seat. This type of mirror is made of a piece of glass that is wedge-shaped in cross section—its front, on manual tilt versions, a tab is used to adjust the mirror between day and night positions. In the day view position, the front surface is tilted, when the mirror is moved to the night view position, its reflecting rear surface is tilted out of line with the drivers view. This view is actually a reflection off the front surface. Manual tilt day/night mirrors first began appearing in the 1930s and became standard equipment on most passenger cars, in the 1950s, American inventor Jacob Rabinow developed a light-sensitive automatic mechanism for the wedge-type day/night mirror. Several automakers began offering rear-view mirrors with automatic dimming again in 1983, current systems usually use photosensors mounted in the rear-view mirror to detect light and dim the mirror by means of electrochromism. This electrochromic feature has also incorporated into side-view mirrors allowing them to dim. On trucks and buses the load often blocks rearward vision out the backlight. In the U. S. virtually all trucks and buses have a side mirror on each side, often mounted on the doors and viewed out the side windows. These mirrors leave a large area behind the vehicle, which tapers down as the distance increases. This is a safety issue which the driver must compensate for, often with a person guiding the truck back in congested areas, or by backing in a curve. “Spot mirrors”, a mirror which provides a distorted image of the entire side of the vehicle, are commonly mounted on at least the right side of a vehicle
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Movie theater
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A movie theater or movie theatre is a venue, usually a building, that contains an auditorium for viewing films, for entertainment. Most, but not all, movie theaters are commercial operations catering to the general public, Some movie theaters, however, are operated by non-profit organizations or societies which charge members a membership fee to view films. The film is projected with a projector onto a large projection screen at the front of the auditorium while the dialogue, sounds. Since the 1970s, subwoofers have used for low-pitched sounds. In the 2010s, most movie theaters are equipped for digital cinema projection, removing the need to create, a great variety of films are shown at cinemas, ranging from animated films for children, blockbusters for general audiences and documentaries for patrons who are interested in non-fiction topics. The smallest movie theaters have a viewing room with a single screen. In the 2010s, most movie theaters have multiple screens, the largest theater complexes, which are called multiplexes—a design developed in the U. S. in the 1960s—have up to 25 screens. The audience members sit on padded seats which in most theaters are set up on a sloped floor. Movie theaters typically sell soft drinks, popcorn and candy and some theaters also sell hot fast food, in some jurisdictions, movie theaters are licensed to sell alcoholic drinks. A movie theater may also be referred to as a theatre, movie house, film house. In the US, theater has long been the preferred spelling, while in the UK, Canada, the latter terms, as well as their derivative adjectives cinematic and kinematic, ultimately derive from Greek κινῆμα, κινήματος —movement, motion. In the countries where those terms are used, the theatre is usually reserved for live performance venues. Colloquial expressions, mostly applied to motion pictures and motion picture theaters collectively, include the silver screen, specific to North American term is the movies, while specific terms in the UK are the pictures, the flicks and for the facility itself the flea pit. A screening room is a theater, often a private one. Open air place in ancient times for viewing spectacles and plays, the term theater comes from the Old French word theatre, from the 12th century and. The use of the theatre to mean a building where plays are shown dates from the 1570s in the English language. The earliest precursors to movies were magic lantern shows, magic lanterns used a glass lens, a shutter and a powerful lamp to project images from glass slides onto a white wall or screen. The invention of the Argand lamp in the 1790s, limelight in the 1820s, the magic lantern could project rudimentary moving images, which was achieved by the use of various types of mechanical slides
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Rear Window Captioning System
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The Rear Window captioning system is a method for presenting, through captions, a transcript of the audio portion of a film in theatres for deaf and hard-of-hearing people. The system was co-developed by WGBH and Rufus Butler Seder, on the way into the theatre, viewers pick up a reflective plastic panel mounted on a flexible stalk. The panel sits in a seat cupholder or on the adjacent to the seat. A large LED display is mounted on a wall that displays caption characters in mirror image. Viewers move the panels into position so they can read the reflected captions, through this method, all screenings of a film can be accessible to caption viewers. Others seated alongside do not watch, or usually even see, Rear Window captioning is an alternative to open captioning, in which text is permanently visible. Open captioning has been little-used due to the fear that it was too intrusive, however, no studies have been conducted to elicit hearing peoples opinions on how they will adapt to reading captions on screen. Rear Window captioning is a form of closed captioning because the viewer must choose to view the captions, few movie exhibitors or theater chains choose to provide Rear Window captioning. One of the often stated for not providing Rear Window captioning is the cost of the hardware. The cost of captioning a film is on the order of US$4,000, for blind viewers, audio description can be and usually is transmitted along with captions. Viewers listen to the descriptions via wireless headsets, in the Rear Window system, the film print is unaffected. With the transition to Digital Cinema, closed captions are included in digital cinema packages. In many movie advertisements by a cinema, the RWC acronym is often used. Often, RWC/DVS notation is used, indicating the availability of both Rear Window Captioning and Descriptive Video Service, national Center for Accessible Media Suzanne Robitaille. Movie Magic for the Hearing Impaired, A simple, inexpensive closed-captioning system exists that would allow millions to go to the cinema, Captioning coming to a theater near you
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Periscope
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A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observers current position. In its simplest form, it consists of a case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles, more complex periscopes, using prisms and/or advanced fiber optics instead of mirrors, and providing magnification, operate on submarines and in various fields of science. The overall design of the submarine periscope is very simple. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction, johannes Hevelius described an early periscope with lenses in 1647 in his work Selenographia, sive Lunae descriptio. Hevelius saw military applications for his invention, in 1854 Hippolyte Marié-Davy invented the first naval periscope, consisting of a vertical tube with two small mirrors fixed at each end at 45°. Simon Lake used periscopes in his submarines in 1902, sir Howard Grubb perfected the device in World War I. Morgan Robertson claimed to have tried to patent the periscope, he described a submarine using a periscope in his fictional works. Periscopes, in some cases fixed to rifles, served in World War I to enable soldiers to see over the tops of trenches, thus avoiding exposure to enemy fire. The Periscope rifle also saw use during the war - this was an infantry rifle sighted by means of a periscope, during World War II, artillery observers and officers used specifically-manufactured periscope binoculars with different mountings. Some of them also allowed estimating the distance to a target, prior to periscopes, vision slits were cut in the armour. In the context of armoured fighting vehicles, such as tanks, in this context a periscope refers to a device that can rotate to provide a wider field of view, while an episcope is fixed into position. A protectoscope is a similar periscopic vision device designed to provide a window in armoured plate, a compact periscope allows the vision slit to be blanked off with armoured plate, preventing an ingress point for small arms fire, with only a small difference in vision height. This design, patented by Rudolf Gundlach in 1936, first saw use in the Polish 7-TP light tank. IV, the Gundlach-Vickers technology was also transferred to the American Army for use in its tanks including the Sherman, built to meet British and US requirements. This saw post-war controversy through legal action, After the Second World War, the USSR also copied the design and used it extensively in its tanks, Germany also made and used copies. The copies were based on lend-lease British vehicles, and many parts remain interchangeable, specialised periscopes can provide sighting or night vision. Periscopes may also be referred to by slang, e. g. shufti-scope, periscopes allow a submarine, when submerged at a relatively shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air
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Non-reversing mirror
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A non-reversing mirror is a mirror that presents its subject as it would be seen from the mirror. A non-reversing mirror can be made by connecting two regular mirrors at their edges at a 90 degree angle, if the join is positioned so that it is vertical, an observer looking into the angle will see a non-reversed image. This can be seen in public toilets when there are mirrors on two walls which are at right angles, Looking towards the corner, such an image is visible. The problem with type of non-reversing mirror is that there is a big line down the middle interrupting the image. However, if first surface mirrors are used, and care is taken to set the angle to exactly 90 degrees, another type of non-reversing mirror can be made by making the mirror concave. At a certain distance from the mirror a non-reversed image will appear, the disadvantage of this is that it only works at a certain distance. A third type of non-reversing mirror was created by mathematics professor R. Andrew Hicks in 2009 and it was created using computer algorithms to generate a disco ball like surface. The thousands of mirrors are angled to create a surface which curves. The curves direct rays from an object across the face before sending them back to the viewer. A patent for a mirror was issued to John Joseph Hooker in 1887. Corner reflector Retroreflector Heres Looking At You See yourself as you really are THE FACE, Do I Look Fat
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Anamorphosis
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Anamorphosis is a distorted projection or perspective requiring the viewer to use special devices or occupy a specific vantage point to reconstitute the image. The word anamorphosis is derived from the Greek prefix ana‑, meaning back or again, an optical anamorphism is the visualization of a mathematical operation called an affine transformation. There are two types of anamorphosis, perspective and mirror. More-complex anamorphoses can be devised using distorted lenses, mirrors, or other optical transformations, examples of perspectival anamorphosis date to the early Renaissance. Examples of mirror anamorphosis were first seen in the late Renaissance, the deformed image is painted on a plane surface surrounding the mirror. By looking into the mirror, a viewer can see the image undeformed, leonardos Eye is the earliest known definitive example of perspective anamorphosis in modern times. The prehistoric cave paintings at Lascaux may also use this technique, Hans Holbein the Younger is well known for incorporating an oblique anamorphic transformation into his painting The Ambassadors. In this artwork, a distorted shape lies diagonally across the bottom of the frame, viewing this from an acute angle transforms it into the plastic image of a human skull, a symbolic memento mori. During the seventeenth century, Baroque trompe loeil murals often used anamorphism to combine actual architectural elements with illusory painted elements, when a visitor views the art work from a specific location, the architecture blends with the decorative painting. The dome and vault of the Church of St. Ignazio in Rome, painted by Andrea Pozzo, due to neighboring monks complaining about blocked light, Pozzo was commissioned to paint the ceiling to look like the inside of a dome, instead of building a real dome. As the ceiling is flat, there is one spot where the illusion is perfect. Mirror anamorphosis emerged early in the 17th century in Italy and China and it remains uncertain whether Jesuit missionaries imported or exported the technique. Anamorphosis could be used to conceal images for privacy or personal safety, a secret portrait of Bonnie Prince Charlie is painted in a distorted manner on a tray and can only be recognized when a polished cylinder is placed in the correct position. To possess such an image would have seen as treason in the aftermath of the 1746 Battle of Culloden. In the eighteenth and nineteenth centuries, anamorphic images had come to be used more as childrens games than fine art, in the twentieth century, some artists wanted to renew the technique of anamorphosis. Marcel Duchamp was interested in anamorphosis, and some of his installations are visual paraphrases of anamorphoses, Jan Dibbets conceptual works, the so-called perspective corrections are examples of linear anamorphoses. In the late century, mirror anamorphosis was revived as childrens toys. Beginning in 1967, Dutch artist Jan Dibbets based a series of photographic work titled Perspective Corrections on the distortion of reality through perspective anamorphosis
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Chirality
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Chirality /kaɪˈrælɪtiː/ is a property of asymmetry important in several branches of science. The word chirality is derived from the Greek, χειρ, hand, an object or a system is chiral if it is distinguishable from its mirror image, that is, it cannot be superposed onto it. Conversely, an image of an achiral object, such as a sphere. A chiral object and its image are called enantiomorphs or. A non-chiral object is called achiral and can be superposed on its mirror image, human hands are perhaps the most universally recognized example of chirality. The left hand is a mirror image of the right hand. This difference in symmetry becomes obvious if someone attempts to shake the hand of a person using their left hand. In mathematics, chirality is the property of a figure that is not identical to its mirror image, in mathematics, a figure is chiral if it cannot be mapped to its mirror image by rotations and translations alone. For example, a shoe is different from a left shoe. A chiral object and its image are said to be enantiomorphs. The word enantiomorph stems from the Greek ἐναντίος opposite + μορφή form, a non-chiral figure is called achiral or amphichiral. The helix and Möbius strip are chiral two dimensional objects in three dimensional ambient space, the J, L, S and Z-shaped tetrominoes of the popular video game Tetris also exhibit chirality, but only in a two dimensional space. Many other familiar objects exhibit the same symmetry of the human body, such as gloves, glasses. A similar notion of chirality is considered in theory, as explained below. Some chiral three dimensional objects, such as the helix, can be assigned a right or left handedness, in geometry a figure is achiral if and only if its symmetry group contains at least one orientation-reversing isometry. In two dimensions, every figure that possesses an axis of symmetry is achiral, and it can be shown that every bounded achiral figure must have an axis of symmetry, in three dimensions, every figure that possesses a plane of symmetry or a center of symmetry is achiral. There are, however, achiral figures lacking both plane and center of symmetry, in terms of point groups, all chiral figures lack an improper axis of rotation. This means that they contain a center of inversion or a mirror plane
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Flopped image
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In photography and graphic arts a flopped image is a technical term for a static or moving image that is generated by a mirror-reversal of an original image across a vertical axis. This is opposed to an image, which means an image reversed across a horizontal axis. Flopping can be used to improve the aesthetic appeal of the image in question. There are two uses in advertising, one practical, and one subjective. On a practical level, images of cars are often flopped to ensure cars look appropriate for left-hand-drive or right-hand-drive markets and this allows the results of a single production shoot to be used across markets, allowing a cost saving. On a subjective level, the direction in which a person is looking or a car appears to be travelling may be regarded as important. Similarly, Vincent van Gogh took the trouble to etch some of his originals in mirror-reversed form so that when printed, people in the image would appear, correctly, as right-handed. An example of flopping is the use of Joseph Edward Southalls painting Fishermen, the picture is flopped, and the name AERIAL added to the boat. A common movie blooper is an image, usually and erroneously called flipped images. Flopped images are common because they can be used to correct continuity errors between shots and are hard to see without extensive examination, whereas flipped images are very obvious, examples of these can be found on several movie blooper sites. One of the most famous flopped images is this picture of Billy the Kid carrying a Model 1873 Winchester rifle and a pistol belt with the pistol on his left. This led people to believe he was left-handed, but it was revealed to be a flopped image due to the cartridge loading gate on the rifle being on the wrong side. The Aesthetics of Mirror Reversal Philosophical Studies 100/2, 175-191, a Note on the Aesthetics of Mirror Reversal Philosophical Studies 132/3, 553-563
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Infinity mirror
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An infinity mirror is a pair of parallel mirrors, which create a series of smaller and smaller reflections that appear to recede into an infinite distance. They are used as accents and in artwork. When an outside observer looks into the surface of the reflective mirror. Alternatively, this effect can also be seen when an observer stands between two parallel fully reflective mirrors, as in some dressing rooms, some elevators, or a house of mirrors. A weaker version of this effect can be seen by standing between any two parallel surfaces, such as the glass walls of a small entry lobby into some buildings. The partially reflective glass produces this sensation, diluted by the noise of the views through the glass into the surrounding environment. The infinity mirror effect is produced there are two parallel reflective surfaces which can bounce a beam of light back and forth an indefinite number of times. The reflections appear to recede into the distance because the light actually is traversing the distance it appears to be traveling, for example, in a two-centimeter-thick infinity mirror, with the light sources halfway between, light from the source initially travels one centimeter. The first reflection travels one centimeter to the mirror and then two centimeters to, and through the front mirror, a total of three centimeters. Each successive reflection adds four more centimeters to the total, each additional reflection adds length to the path the light must travel before exiting the mirror. If the mirrors are not precisely parallel, but instead are canted at a slight angle, in theory, such a surface is infinite in area, but encloses a finite volume. Visual artists, especially contemporary sculptors, have use of infinity mirrors. Yayoi Kusama, Josiah McElheny, Ivan Navarro, and Taylor Davis have all produced works that use the infinity mirror to expand the sensation of unlimited space in their artworks. Some amusement park rides, such as Disneys Space Mountain roller coaster attraction. Corner reflector Kaleidoscope Recursion § In art
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Kaleidoscope
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The reflectors are usually enclosed in a tube, often containing on one end a cell with loose, colored pieces of glass or other transparent materials to be reflected into the viewed pattern. Rotation of the cell causes motion of the materials, resulting in an ever changing viewed pattern, a kaleidoscope operates on the principle of multiple reflection, where two or more reflectors are placed at an angle to one another. When the eye is placed at one end of the reflectors, for irregular objects situated at any position the angle should be an even aliquot part of 360°. The reflected object should be in contact with the ends of the reflectors, the eye should be as near as possible to the angular point of the ends of the reflector opposite the reflected object. An object-box on the ends of the reflectors can hold selected objects to be viewed in the reflected pattern, colorful transparent shapes to create beautiful patterns. Objects smaller than the aperture create an appearance of the pattern. Larger opaque objects and darker colors dont transmit much light and are usually avoided, if objects, fragments and/or liquids are loosely placed inside the cell and tumble when the cell is rotated, motion and change of colors and shapes can be introduced into the viewed pattern. Multiple reflection by two or more reflecting surfaces has been known since antiquity and was described by as such by Giambattista della Porta in his Magia Naturalis. Mr. Bradleys New Improvements in Planting and Gardening described a similar construction to be placed on geometrical drawings to show an image with multiplied reflection, however, an optimal configuration that produces the full effects of the kaleidoscope have not been recorded before 1815. He forgot about it, but noticed a more impressive version of the effect during experiments in February 1815. This triggered more experiments to find the conditions for the most beautiful, a version followed in which some of the objects and pieces of glass could move when the tube was rotated. The last step, regarded as most important by Brewster, was to place the reflecting panes in a tube with a concave lens to distinctly introduce surrounding objects into the reflected pattern. Brewster thought his instrument to be of value in all the ornamental arts as a device that creates an infinity of patterns. Artists could accurately delineate the produced figures of the kaleidoscope by means of the solar micoscope, Brewster believed it would at the same time become a popular instrument for the purposes of rational amusement. He decided to apply for a patent, british patent no.4136 for a new Optical Instrument called The Kaleidoscope for exhibiting and creating beautiful Forms and Patterns of great use in all the ornamental Arts was granted in July 1817. Unfortunately the manufacturer originally engaged to produce the product had one of the patent instruments to some of the London opticians to see if he could get orders from them. Soon the instrument was copied and marketed before the manufacturer had prepared any number of kaleidoscopes for sale, an estimated two hundred thousand kaleidoscopes sold in London and Paris in just three months. Brewster figured at most a thousand of these were authorized copies that were constructed correctly and it was thought that the patent was reduced in a Court of Law since its principles were supposedly already known
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Reflection (physics)
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Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves, the law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. In acoustics, reflection causes echoes and is used in sonar, in geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water, Reflection is observed with many types of electromagnetic wave, besides visible light. Reflection of VHF and higher frequencies is important for radio transmission, even hard X-rays and gamma rays can be reflected at shallow angles with special grazing mirrors. Reflection of light is either specular or diffuse depending on the nature of the interface, a mirror provides the most common model for specular light reflection, and typically consists of a glass sheet with a metallic coating where the reflection actually occurs. Reflection is enhanced in metals by suppression of wave propagation beyond their skin depths, Reflection also occurs at the surface of transparent media, such as water or glass. In the diagram, a light ray PO strikes a vertical mirror at point O, by projecting an imaginary line through point O perpendicular to the mirror, known as the normal, we can measure the angle of incidence, θi and the angle of reflection, θr. The law of reflection states that θi = θr, or in other words, in fact, reflection of light may occur whenever light travels from a medium of a given refractive index into a medium with a different refractive index. In the most general case, a fraction of the light is reflected from the interface. This is analogous to the way impedance mismatch in a circuit causes reflection of signals. Total internal reflection of light from a denser medium occurs if the angle of incidence is above the critical angle, total internal reflection is used as a means of focusing waves that cannot effectively be reflected by common means. X-ray telescopes are constructed by creating a tunnel for the waves. As the waves interact at low angle with the surface of this tunnel they are reflected toward the focus point, a conventional reflector would be useless as the X-rays would simply pass through the intended reflector. When light reflects off a material denser than the external medium, in contrast, a less dense, lower refractive index material will reflect light in phase. This is an important principle in the field of thin-film optics, specular reflection at a curved surface forms an image which may be magnified or demagnified, curved mirrors have optical power. Such mirrors may have surfaces that are spherical or parabolic, if the reflecting surface is very smooth, the reflection of light that occurs is called specular or regular reflection. The laws of reflection are as follows, The incident ray, the reflected ray, the angle which the incident ray makes with the normal is equal to the angle which the reflected ray makes to the same normal
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Relative direction
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Direction is the information vested in the relative position of a destination point with respect to a starting point, absent the distance information. Directions may be relative to some indicated reference, or absolute according to some previously agreed upon frame of reference. Direction is often indicated manually by an index finger or written as an arrow. On a vertically oriented sign representing a plane, such as a road sign. Mathematically, direction may be specified by a direction vector, or equivalently by the angles made by the most direct path with respect to a specified set of axes. Examples of 2D and 3D directions represented numerically by direction vectors are shown, the same unit vector construct is used to specify spatial directions in 2D, 3D or higher dimensions. As illustrated, each unique 2D direction is equivalent numerically to a point on the circle, while each unique 3D direction may be represented numerically as a point on the unit sphere. For example, in software where 2D direction is represented by angle theta, 2D direction vectors vary continuously while offering 1,1 representation, thus eliminating a singularity exception to be handled. Representational simplicity is even greater for direction vectors in 3D, as compared to polar angle-pair, in Euclidean and affine geometry, the direction of a subspace is the vector space associated to this subspace. In the case of a subspace of one the direction vectors are the nonzero vectors of this vector space. Cardinal direction Compass Direction vector Navigation Radio direction finder Relative direction Affine space
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The Straight Dope
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The Straight Dope is an online question-and-answer newspaper column published in the Chicago Reader and syndicated in eight newspapers in the United States. The column appears under the tagline, Fighting ignorance since 1973, first published by the Reader in 1973, the column is written by Cecil Adams and illustrated by Slug Signorino. To date, Adams has published five collections of his columns, in 1996, the A&E Network briefly aired a show based on the column called The Straight Dope, hosted and co-written by comedian Mike Lukas. A podcast has also released sporadically. Urban legend Snopes. com FactCheck. org TruthOrFiction. com The Skeptics Dictionary MythBusters List of common misconceptions The Straight Dope The Straight Dope at the Internet Movie Database
