Mirror

They also were used as a portal to another world in Lewis Carroll's Through the Looking Glass. This use can be questioned, as many freely growing plants are poisonous, for example. In Tlön, Uqbar, Orbis Tertius, a fictional heresiarch declares that "mirrors and copulation are abominable, since they both multiply the numbers of men.". Natural is often used meaning "good", "healthy", or "belonging to human nature". In Dreamtigers, he writes of fearing that his reflection would move independently or change shape before his eyes. Natural is defined as "of or relating to nature"; this applies to both definitions of 'nature': 'essence' ("one's true nature") and 'the untouched world' ("force of nature"). Mirrors, along with labyrinths, figure prominently in the work of Argentine writer Jorge Luis Borges, who often used them as symbols of infinity, impersonation, and illusion. United States Natural Law Party, a political arm of the Transcendental Meditation movement.

Illuminated rotating disco balls covered with small mirrors are used to cast moving spots of light around a dance floor. Naturalism (philosophy), stances deriving from materialism and pragmatism. Mirrors are often used in magic to create an illusion. Natural units, in physics, a set of measurement units, originally proposed by Max Planck. The hall of mirrors, commonly found in amusement parks, is an attraction in which a number of distorted mirrors are used to produce unusual reflections of the visitor. Natural transformation, in mathematics, a means of transforming functors in category theory. This technique was used by Native American tribes and numerous militaries to transmit information between distant outposts. Natural theology, theology based on reason and experience.

The signal can be used over long distances, possibly up to 60 kilometres on a clear day. Natural semantic metalanguage, in linguistics, an approach to semantic analysis. With the sun as light source, a mirror can be used to signal, by variations in the orientation of the mirror. Natural selection, alteration of biological populations over time (one of the foundations of the theory of evolution). A decorative reflecting sphere of thin metal-coated glass, working as a reducing wide-angle mirror, is sold as a Christmas tree decoration called a bauble. Natural science, study of the non-human aspects of the world. Mirrors, typically large and unframed, are frequently used in interior decoration to create an illusion of space, and amplify the apparent size of a room. Natural satellite, a moon or similar naturally occurring planetary satellite.

Its purpose is to split a beam of light so that half passes straight through, while the other half is reflected — this is useful for interferometry. Natural resource, naturally occurring commodities valued in their (relatively) unprocessed form. The same type of mirror, when used in an optical instrument, is called a half-silvered mirror or beam splitter. Natural programming language. It may be used to observe criminal suspects or customers (to watch out for theft). natural number, in mathematics, numbers 1,2,3,... Persons on the dark side see through it - it looks like a transparent window. Natural monopoly, in economics, a monopoly persisting for fundamental economic reasons.

Persons on the brightly lit side see their own reflection - it looks like a normal mirror. Natural logarithm, in mathematics, logarithm to base e. It is used between a dark room and a brightly lit room. Natural Law Party, the political arm of the Transcendental Meditation movement. It is a sheet of glass coated with a layer of metal only a few dozen atoms thick, allowing some of the light through the surface (from both sides). Natural law, in law or morals, system of justice conceived as independent of current political order. A one-way mirror, also called two-way mirror, reflects about half of the light and lets the other half pass. Natural language processing, in computer science, computer comprehension of human language.

Use of a large number of mirrors in a confined space can act to satisfy people's desire for satisfication of their ego, as in the hall of mirrors in the Palace of Versailles. Natural language, human language spoken natively, as opposed to purely constructed languages. Other uses of mirrors in hedonistic acts include the classic 'mirror on the ceiling' for use during sex (see The Eagles' Hotel California), and the use of mirrors for 'cutting' and snorting cocaine. Natural History (disambiguation), for various works titled Natural History. upskirt. Natural history, a broad term for the study of living things. A mirror is sometimes used for voyeurism, e.g. Natural footed, in surfing, left foot forward.

High quality flat mirrors are essential for making corner reflectors, which are used for emergency location, and even laser ranging to the Moon. Natural food movement, a diet emphasizing unprocessed food. Mirrors are also sometimes used as part of security systems, so that a single video camera can show more than one angle at a time. Natural family planning, contraceptive methods permitted by the Catholic Church. Rounded (convex) mirrors are sometimes placed at road junctions, and corners of places such as parking lots or stores, allowing people to see around corners to avoid crashing into other vehicles or shopping carts. Natural environment, an environment on earth or elsewhere not primarily of human creation. There exist rear view sunglasses, of which the left end of the left glass and the right end of the right glass work as mirrors. Natural disaster, such as earthquakes, huricanes, etc.

Some motorcycle helmets have a built-in so-called MROS (Multiple Reflective Optic System): a set of reflective surfaces inside the helmet which together function as a rear-view mirror [1]. Natural deduction, in mathematics, a class of foundational approaches to proofs. Rear-view mirror are applied in and on vehicles (such as cars, or bicycles), to allow drivers to see other vehicles coming up behind them. Natural childbirth, childbirth with minimal medical intervention. In astronomy, adaptive optics is a technique to measure variable image distortions and adapt a mirror accordingly on a timescale of milliseconds, to compensate for the distortions. Natural capitalism, a set of economic reforms to reward efficiency. Such mirrors are often used in lasers. Natural capital, in economics, the naturally occurring resources in the earth's biosphere.

The best mirrors of this type can reflect >99.999% of the light (in a narrow range of wavelengths) which is incident on the mirror. Natural arch, naturally occurring rock formation. By careful choice of the type and thickness of the dielectric layers, the range of wavelengths and amount of light reflected from the mirror can be specified. Natural abundance, in physics, the relative quantities of isotopes found in nature. These are glass (or sometimes other material) substrates on which one or more layers of dielectric material are deposited, to form an optical coating. Иatural, an album by Japanese alternative rock group Orange Range. For scientific optical work, dielectric mirrors are often used. Natural (♮), in music, are the notes A, B, C, D, E, F, and G, as opposed to the sharps/flats.

The reflectivity as a function of wavelength depends on both the thickness of the coating and on how it is applied. For instance, aluminum mirrors are commonly coated with magnesium fluoride. Mirror surfaces are sometimes given thin film overcoatings both to retard degradation of the surface and to increase their reflectivity in parts of the spectrum where they will be used. A hot mirror is the opposite, the coating preferentially reflects infrared.

A cold mirror is made by using a transparent substrate and choosing a coating material that is more reflective to visible light and more transmissive to infrared light. This is exploited in some optical work to make cold mirrors and hot mirrors. The reflectivity of the mirror coating can be measured using a reflectometer and depends on the wavelength of light as well as the metal. Front silvered mirrors have to be resurfaced occasionally to keep their quality.

A protective overcoat is usually applied before the mirror is removed from the vacuum, because the coating otherwise begins to corrode as soon as it is exposed to oxygen and humidity in the air. The coatings are typically applied by vacuum deposition. They reflect 90% to 95% of the incident light when new. All of these coatings are easily damaged and require special handling.

Some of them use silver, but most are aluminum, which is more reflective at short wavelengths than silver. Telescopes and other precision instruments use front silvered mirrors, where the reflecting surface is placed on the front surface of the glass, which gives better image quality. This may be to check physical appearance (including clothing, make-up, hair, etc.) or to control applying make-up, shaving, cutting hair, fixing one's tie, etc. A mirror is used for inspecting parts of one's body which are difficult or impossible to see directly, such as the face, neck or the whole body.

The "back side" of the mirror is often painted black to completely seal the metal from corrosion. This type of mirror reflects about 80% of the incident light. They are back silvered, where the reflecting surface is viewed through the glass sheet; this makes the mirror durable, but lowers the image quality of the mirror due to extraneous reflections from the front surface of the glass. Most modern mirrors consist of a thin layer of aluminium deposited on a sheet of glass.

Early mirrors were usually a sheet of polished metal, often silver or copper, for example the Aranmula kannadi. In either case, an observer farther from the mirror than you will see your normal orientation directly and in the mirror before you turn, and will then observe that you put your right hand where your left was if you rotate the usual way, or your head where your feet were if you stand on your head. If one rotated about a horizontal axis parallel to the mirror surface, one would appear upside down. The question is sometimes asked, "Why does the mirror reverse left to right and not top to bottom?" The answer is that one has rotated (as is most comfortable) about a vertical axis to face the mirror.

When the rotation is so obvious that it is not worth mentioning, the second component in this decomposition of the effect of the mirror is sometimes emphasized, by saying that a mirror "reverses left and right". In particular, if one looks at one's image in a vertical mirror in left-right orientation, the image corresponds to a rotation by 180° about the vertical axis in the mirror, combined with a reflection in one's approximate symmetry plane. In this case the image of the person is in normal standing orientation and vertically in a normal position, at a horizontally different position and with an orientation rotated about a vertical axis, the latter except if the mirror is parallel to the approximate symmetry plane of the person. This is the case iff the mirror is vertical.

The image is the most realistic if it is still vertical, i.e., if the rotation is about a vertical axis. We can apply this to the image in a mirror of, say, a standing person, because people have approximate bilateral symmetry. For an object with approximate reflection symmetry, a reflection in some mirror plane corresponds to a combination of:. That is, if the beam of light is shining on a mirror's surface at a 30° angle from vertical, then it reflects from the point of incidence at a 30° angle from vertical in the opposite direction.

A beam of light reflects off a mirror at an angle of reflection that is equal to its angle of incidence. Note that spherical concave and convex mirrors do not have a single focal point, as often described in high school physics text books (see spherical aberration in lens (optics) and aberration in optical systems). Finally, there are convex mirrors, where a parallel beam becomes divergent, with the apparent intersection occurring behind the mirror. There are also parabolic concave mirrors, where a parallel beam of light becomes a convergent beam, whose rays intersect in the focus of the mirror.

In a plane mirror, a parallel beam of light changes its direction as a whole, whilst still remaining parallel; the images formed by a plane mirror are virtual images, of the same size as the original object (see mirror image). . The most common use is in the home for personal grooming but mirrors are also used in scientific apparatus such as telescopes and lasers, and in industrial machinery. The best known example is the plane mirror.

A mirror is a surface with good specular reflection that is smooth enough to form an image. a reflection in the approximate symmetry plane of the object (due to the assumption this is a minor change). a translation if the mirror is parallel to the symmetry plane of the object, and otherwise a rotation about the line of intersection of the two planes by an angle which is twice the angle between the two planes.