Mirror

They also were used as a portal to another world in Lewis Carroll's Through the Looking Glass. Though Jesus's birth is celebrated on December 25, most scholars agree that it is unlikely he was actually born on this date. In Tlön, Uqbar, Orbis Tertius, a fictional heresiarch declares that "mirrors and copulation are abominable, since they both multiply the numbers of men.". Live Nativity scenes are also re-inacted using Human actors and live animals to portray the event with more realism. In Dreamtigers, he writes of fearing that his reflection would move independently or change shape before his eyes. Many Christians also display a small re-creation of the Nativity known as a Nativity scene in their homes, using small figurines to portray the key characters of the event. 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. In some Christian churches, children often perform plays re-creating the events of the Nativity, or sing some of the numerous Christmas carols that reference the event.

Illuminated rotating disco balls covered with small mirrors are used to cast moving spots of light around a dance floor. For example, the Eastern Orthodox Church practices the Nativity Fast in anticipation of the birth of Jesus Christ, while the Roman Catholic Church celebrates Advent. Mirrors are often used in magic to create an illusion. Remembering or re-creating the Nativity is one of the central ways that Christians celebrate Christmas. 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. They subsequently publisized what they had witnessed throughout the area. This technique was used by Native American tribes and numerous militaries to transmit information between distant outposts. The shepherds went quickly to Bethlehem, finding the sign to be as the angel foretold.

The signal can be used over long distances, possibly up to 60 kilometres on a clear day. This is the sign to you: you will find a baby wrapped in strips of cloth (swadling clothes), lying in a feeding trough (manger)." After this an innumerable company of angels appeared with the herald singing "Glory to God in the highest, on earth peace, good will toward men." (see The First Noël). With the sun as light source, a mirror can be used to signal, by variations in the orientation of the mirror. Also present at the scene, according to Luke's account, were local shepherds who were visited in the night by an angel (herald) who said "Don't be afraid, for behold, I bring you good news of great joy which will be to all the people, for there is born to you, this day, in the city of David, a Savior, who is Christ the Lord. 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. The tradition that they were three probably comes from the number of gifts they presented. 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. The source of this story is Gospel of Matthew, although the number, exact origin, and, for that matter, gender of the Magi are unspecified there.

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. The star's zenith was apparently directly over the city of Bethlehem, and it disappeared soon after they visited the child. The same type of mirror, when used in an optical instrument, is called a half-silvered mirror or beam splitter. The men were said to be following a mysterious star, commonly known as the Star of Bethlehem, that had suddenly appeared in the sky, believing it to be to be the fulfillment of an ancient prophecy of the coming of the Messiah, or king of the Jews. It may be used to observe criminal suspects or customers (to watch out for theft). There is also a traditional depiction of three wise men from Persia visiting the event, bearing gifts of gold, frankincense, and myrrh. Persons on the dark side see through it - it looks like a transparent window. Also, some biblical scholars believe that the use of the word "inn" in the recounting of the birth of Jesus may be the result of the mistranslation of one of two similar words meaning a "gathering room" (in a home) or "host's home".

Persons on the brightly lit side see their own reflection - it looks like a normal mirror. The Bible does not specifically mention an inn keeper or a stable or even animals (except the flocks of the sheperds) relating to the birth of Jesus. It is used between a dark room and a brightly lit room. Others believe that the manger was not in a stable at all but in a lower floor room of a building or house where agricultural tools and grain stores were normally kept, but where animals were brought into on cold nights or to protect them from thieves. 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). Although the event is usually depicted as taking place in a man-made free standing structure, many biblical scholars believe that the stable was probably a cave carved in the side of a hill. A one-way mirror, also called two-way mirror, reflects about half of the light and lets the other half pass. The whole city was full of people who had made the pilgrimage to the city of David and as a result there was no room for the expecting couple at the town's inn.

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. The odd location of the birth was the result of Joseph and Mary being forced by order of Herod the Great to leave their homes in Nazareth and come to the home of Joseph's ancestors, the house of David, for a census. 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. The baby Jesus was born into a manger from the Virgin Mary assisted by her husband Joseph. upskirt. According to traditional telling of the birth of Jesus Christ, Jesus was born in the city of Bethlehem in a stable, surrounded by farm animals and shepherds. A mirror is sometimes used for voyeurism, e.g. The Nativity refers to the birth of Jesus.

High quality flat mirrors are essential for making corner reflectors, which are used for emergency location, and even laser ranging to the Moon. Nativity can be applied to abstractions like a genre such as Blues music or a particular discipline like the Scientific method. 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. In this sense, a person's nativity is construed (or misconstrued) to form a basis for a general impression based on national origin or ethnicity. 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. The term can also apply to cultural appropriation to identify the specific and general situation, as in Native land, language, political system and environment of a person. 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. The term has evolved a strong association, at least in Western civilization through the influences of Christianity to the nativity of Jesus of Nazareth iconified as simply The Nativity.

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]. Nativity is the general time and place of a person's birth and early years. 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. 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. Such mirrors are often used in lasers.

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. 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. These are glass (or sometimes other material) substrates on which one or more layers of dielectric material are deposited, to form an optical coating. For scientific optical work, dielectric mirrors are often used.

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.