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# Polarization (waves)

Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. [1]

202 relations: Absolute phase, Absolute value, Aerosol, American and British English spelling differences, Angle of incidence (optics), Angular frequency, Angular momentum, Angular spectrum method, Animal, Anisotropy, Antenna (radio), Astronomy, Atlantic Ocean, Atmosphere of Earth, Attenuation, Axial ratio, Étienne-Louis Malus, Backlight, Basis (linear algebra), Basis function, Bee, Bee learning and communication, Birefringence, Brewster's angle, Calcite, Cathode ray tube, Cellophane, Charles Wheatstone, Chirality, Circular polarization, Cloud, Coherence (physics), Columbidae, Compass, Complex number, Correlation and dependence, Cosmic dust, Cosmic microwave background, Crystal, Cuttlefish, David Pye (zoologist), Degree of polarization, Depolarizer (optics), Dichroism, Dispersion (optics), Earth's magnetic field, Eigenvalues and eigenvectors, Elastography, Electric displacement field, Electric field, ... Expand index (152 more) »

## Absolute phase

Absolute phase refers to the phase of a waveform relative to some standard (strictly speaking, phase is always relative).

## Absolute value

In mathematics, the absolute value or modulus of a real number is the non-negative value of without regard to its sign.

## Aerosol

An aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas.

## American and British English spelling differences

Many of the differences between American and British English date back to a time when spelling standards had not yet developed.

## Angle of incidence (optics)

In geometric optics, the angle of incidence is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal.

## Angular frequency

In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.

## Angular momentum

In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.

## Angular spectrum method

The angular spectrum method is a technique for modeling the propagation of a wave field.

## Animal

Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia.

## Anisotropy

Anisotropy, is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy.

In radio, an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver.

## Astronomy

Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

## Atlantic Ocean

The Atlantic Ocean is the second largest of the world's oceans with a total area of about.

## Atmosphere of Earth

The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.

## Attenuation

In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a medium.

## Axial ratio

Axial ratio, for any structure or shape with two or more axes, is the ratio of the length (or magnitude) of those axes to each other - the longer axis divided by the shorter.

## Étienne-Louis Malus

Étienne-Louis Malus (23 July 1775 &ndash; 24 February 1812) was a French officer, engineer, physicist, and mathematician.

## Backlight

A backlight is a form of illumination used in liquid crystal displays (LCDs).

## Basis (linear algebra)

In mathematics, a set of elements (vectors) in a vector space V is called a basis, or a set of, if the vectors are linearly independent and every vector in the vector space is a linear combination of this set.

## Basis function

In mathematics, a basis function is an element of a particular basis for a function space.

## Bee

Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the European honey bee, for producing honey and beeswax.

## Bee learning and communication

Honey bees are sensitive to odors (including pheromones), tastes, and colors, including ultraviolet.

## Birefringence

Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light.

## Brewster's angle

Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection.

## Calcite

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3).

## Cathode ray tube

The cathode ray tube (CRT) is a vacuum tube that contains one or more electron guns and a phosphorescent screen, and is used to display images.

## Cellophane

Cellophane is a thin, transparent sheet made of regenerated cellulose.

## Charles Wheatstone

Sir Charles Wheatstone FRS (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three-dimensional images), and the Playfair cipher (an encryption technique).

## Chirality

Chirality is a property of asymmetry important in several branches of science.

## Christmas

Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.

## Christmas and holiday season

The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.

## Christmas Eve

Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.

Christmas traditions vary from country to country.

## Circular polarization

In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.

## Cloud

In meteorology, a cloud is an aerosol consisting of a visible mass of minute liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body.

## Coherence (physics)

In physics, two wave sources are perfectly coherent if they have a constant phase difference and the same frequency, and the same waveform.

## Columbidae

Pigeons and doves constitute the animal family Columbidae and the order Columbiformes, which includes about 42 genera and 310 species.

## Compass

A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal directions (or points).

## Complex number

A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.

## Correlation and dependence

In statistics, dependence or association is any statistical relationship, whether causal or not, between two random variables or bivariate data.

## Cosmic dust

Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, as well as all over planet Earth.

## Cosmic microwave background

The cosmic microwave background (CMB, CMBR) is electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology.

## Crystal

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

## Cuttlefish

Cuttlefish or cuttles are marine animals of the order Sepiida. They belong to the class Cephalopoda, which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone. Despite their name, cuttlefish are not fish but molluscs. Cuttlefish have large, W-shaped pupils, eight arms, and two tentacles furnished with denticulated suckers, with which they secure their prey. They generally range in size from, with the largest species, Sepia apama, reaching in mantle length and over in mass. Cuttlefish eat small molluscs, crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other cuttlefish. The average life expectancy of a cuttlefish is about one to two years. Recent studies indicate cuttlefish are among the most intelligent invertebrates. (television program) NOVA, PBS, April 3, 2007. Cuttlefish also have one of the largest brain-to-body size ratios of all invertebrates. The 'cuttle' in 'cuttlefish' comes from the Old English name for the species, cudele, which may be cognate with the Old Norse koddi ('cushion') and the Middle Low German Kudel ('rag'). The Greco-Roman world valued the cuttlefish as a source of the unique brown pigment the creature releases from its siphon when it is alarmed. The word for it in both Greek and Latin, sepia, now refers to the reddish-brown color sepia in English.

## David Pye (zoologist)

John David Pye, commonly known as David Pye (born 1932) is a British zoologist who is an Emeritus Professor of Queen Mary, University of London.

## Degree of polarization

Degree of polarization (DOP) is a quantity used to describe the portion of an electromagnetic wave which is polarized.

## Depolarizer (optics)

A depolarizer or depolariser is an optical device used to scramble the polarization of light.

## Dichroism

In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are absorbed by different amounts.

## Dispersion (optics)

In optics, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency.

## Earth's magnetic field

Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it meets the solar wind, a stream of charged particles emanating from the Sun.

## Eigenvalues and eigenvectors

In linear algebra, an eigenvector or characteristic vector of a linear transformation is a non-zero vector that changes by only a scalar factor when that linear transformation is applied to it.

## Elastography

Elastography is a medical imaging modality that maps the elastic properties and stiffness of soft tissue.

## Electric displacement field

In physics, the electric displacement field, denoted by D, is a vector field that appears in Maxwell's equations.

## Electric field

An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.

## Electric susceptibility

In electricity (electromagnetism), the electric susceptibility (\chi_; Latin: susceptibilis "receptive") is a dimensionless proportionality constant that indicates the degree of polarization of a dielectric material in response to an applied electric field.

In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.

## Elliptical polarization

In electrodynamics, elliptical polarization is the polarization of electromagnetic radiation such that the tip of the electric field vector describes an ellipse in any fixed plane intersecting, and normal to, the direction of propagation.

## Emil Wolf

Emil Wolf (July 30, 1922 – June 2, 2018) was a Czech-born American physicist who made advancements in physical optics, including diffraction, coherence properties of optical fields, spectroscopy of partially coherent radiation, and the theory of direct scattering and inverse scattering.

## Enantiomer

In chemistry, an enantiomer, also known as an optical isomer (and archaically termed antipode or optical antipode), is one of two stereoisomers that are mirror images of each other that are non-superposable (not identical), much as one's left and right hands are the same except for being reversed along one axis (the hands cannot be made to appear identical simply by reorientation).

## Engineering

Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations.

## Equatorial coordinate system

The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects.

## Extinction ratio

In telecommunications, extinction ratio (re) is the ratio of two optical power levels of a digital signal generated by an optical source, e.g., a laser diode.

In physics, the Faraday effect or Faraday rotation is a magneto-optical phenomenon—that is, an interaction between light and a magnetic field in a medium.

## Fluid

In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress.

## Fluorescence anisotropy

Fluorescence anisotropy or fluorescence polarization is the phenomenon where the light emitted by a fluorophore has unequal intensities along different axes of polarization.

## Fresnel equations

The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media.

## Geology

Geology (from the Ancient Greek γῆ, gē, i.e. "earth" and -λoγία, -logia, i.e. "study of, discourse") is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time.

## Ghosting (television)

In television, a ghost is a replica of the transmitted image, offset in position, that is super-imposed on top of the main image.

## Glan–Taylor prism

A Glan–Taylor prism is a type of prism which is used as a polarizer or polarizing beam splitter.

## Gravitational wave

Gravitational waves are the disturbance in the fabric ("curvature") of spacetime generated by accelerated masses and propagate as waves outward from their source at the speed of light.

## Gravity wave

In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium.

## Group delay and phase delay

In signal processing, group delay is the time delay of the amplitude envelopes of the various sinusoidal components of a signal through a device under test, and is a function of frequency for each component.

## Haidinger's brush

Haidinger's brush is an entoptic phenomenon first described by Austrian physicist Wilhelm Karl von Haidinger in 1844.

## Helix

A helix, plural helixes or helices, is a type of smooth space curve, i.e. a curve in three-dimensional space.

## Hermitian matrix

In mathematics, a Hermitian matrix (or self-adjoint matrix) is a complex square matrix that is equal to its own conjugate transpose—that is, the element in the -th row and -th column is equal to the complex conjugate of the element in the -th row and -th column, for all indices and: Hermitian matrices can be understood as the complex extension of real symmetric matrices.

## Homing pigeon

The homing pigeon is a variety of domestic pigeon (Columba livia domestica) derived from the rock pigeon, selectively bred for its ability to find its way home over extremely long distances.

## Homogeneity (physics)

In physics, a homogeneous material or system has the same properties at every point; it is uniform without irregularities.

## Horizontal coordinate system

The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane.

## Human eye

The human eye is an organ which reacts to light and pressure.

## Idempotence

Idempotence is the property of certain operations in mathematics and computer science that they can be applied multiple times without changing the result beyond the initial application.

## Impedance of free space

The impedance of free space,, is a physical constant relating the magnitudes of the electric and magnetic fields of electromagnetic radiation travelling through free space.

## Incandescent light bulb

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to such a high temperature that it glows with visible light (incandescence).

## Inner product space

In linear algebra, an inner product space is a vector space with an additional structure called an inner product.

## Insect

Insects or Insecta (from Latin insectum) are hexapod invertebrates and the largest group within the arthropod phylum.

## Intensity (physics)

In physics, intensity is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy.

## Ionosphere

The ionosphere is the ionized part of Earth's upper atmosphere, from about to altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere.

## Isotropy

Isotropy is uniformity in all orientations; it is derived from the Greek isos (ἴσος, "equal") and tropos (τρόπος, "way").

## Jones calculus

In optics, polarized light can be described using the Jones calculus, discovered by R. C. Jones in 1941.

## Kerr effect

The Kerr effect, also called the quadratic electro-optic (QEO) effect, is a change in the refractive index of a material in response to an applied electric field.

## Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

## Light

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.

## Linear dichroism

Linear dichroism (LD) or diattenuation describes the property of a material whose transmittance depends on the orientation of linearly polarized light incident upon it.

## Linear map

In mathematics, a linear map (also called a linear mapping, linear transformation or, in some contexts, linear function) is a mapping between two modules (including vector spaces) that preserves (in the sense defined below) the operations of addition and scalar multiplication.

## Linear polarization

In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation.

## Liquid-crystal display

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals.

## Log-periodic antenna

A log-periodic antenna (LP), also known as a log-periodic array or log-periodic aerial, is a multi-element, directional antenna designed to operate over a wide band of frequencies.

## Longitudinal wave

Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave.

## Magnetic field

A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.

## Mantis shrimp

Mantis shrimps, or stomatopods, are marine crustaceans of the order Stomatopoda.

## Maser

A maser (an acronym for "microwave amplification by stimulated emission of radiation") is a device that produces coherent electromagnetic waves through amplification by stimulated emission.

## Matrix (mathematics)

In mathematics, a matrix (plural: matrices) is a rectangular array of numbers, symbols, or expressions, arranged in rows and columns.

## Microscope

A microscope (from the μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is an instrument used to see objects that are too small to be seen by the naked eye.

## Microwave

Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between and.

## Mineral

A mineral is a naturally occurring chemical compound, usually of crystalline form and not produced by life processes.

## Mineralogy

Mineralogy is a subject of geology specializing in the scientific study of chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts.

## Momentum

In Newtonian mechanics, linear momentum, translational momentum, or simply momentum (pl. momenta) is the product of the mass and velocity of an object.

## Mueller calculus

Mueller calculus is a matrix method for manipulating Stokes vectors, which represent the polarization of light.

## New Year

New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.

## New Year's Day

New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.

## New Year's Eve

In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.

## Nicol prism

A Nicol prism is a type of polarizer, an optical device used to produce a polarized beam of light.

## Norbert Wiener

Norbert Wiener (November 26, 1894 – March 18, 1964) was an American mathematician and philosopher.

## Octopus

The octopus (or ~) is a soft-bodied, eight-armed mollusc of the order Octopoda.

## Optical fiber

An optical fiber or optical fibre is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair.

## Optical mineralogy

Optical mineralogy is the study of minerals and rocks by measuring their optical properties.

## Optical rotation

Optical rotation or optical activity (sometimes referred to as rotary polarization) is the rotation of the plane of polarization of linearly polarized light as it travels through certain materials.

## Optics

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.

## Organic compound

In chemistry, an organic compound is generally any chemical compound that contains carbon.

## Orthogonality

In mathematics, orthogonality is the generalization of the notion of perpendicularity to the linear algebra of bilinear forms.

## Oscillation

Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states.

## Outer space

Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies.

## Permeability (electromagnetism)

In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself.

## Phase factor

For any complex number written in polar form (such as reiθ), the phase factor is the complex exponential factor (eiθ).

## Phasor

In physics and engineering, a phasor (a portmanteau of phase vector), is a complex number representing a sinusoidal function whose amplitude (A), angular frequency (ω), and initial phase (θ) are time-invariant.

## Photon

The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).

## Plane of incidence

In describing reflection and refraction in optics, the plane of incidence (also called the meridional plane) is the plane which contains the surface normal and the propagation vector of the incoming radiation.

## Plane wave

In the physics of wave propagation, a plane wave (also spelled planewave) is a wave whose wavefronts (surfaces of constant phase) are infinite parallel planes.

## Plasma (physics)

Plasma (Henry George Liddell, Robert Scott, A Greek English Lexicon, on Perseus) is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s.

## Plastic

Plastic is material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects.

## Pockels effect

The Pockels effect (after Friedrich Carl Alwin Pockels who studied the effect in 1893), or Pockels electro-optic effect, changes or produces birefringence in an optical medium induced by an electric field.

## Polarimeter

A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance.

## Polarization (waves)

Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations.

## Polarization rotator

A polarization rotator is an optical device that rotates the polarization axis of a linearly polarized light beam by an angle of choice.

## Polarized 3D system

A polarized 3D system uses polarization glasses to create the illusion of three-dimensional images by restricting the light that reaches each eye (an example of stereoscopy).

## Polarized light microscopy

Polarized light microscopy can mean any of a number of optical microscopy techniques involving polarized light.

## Polarizer

A polarizer or polariser is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations.

## Polaroid (polarizer)

Polaroid is a type of synthetic plastic sheet which is used as a polarizer or polarizing filter.

## Probability distribution

In probability theory and statistics, a probability distribution is a mathematical function that provides the probabilities of occurrence of different possible outcomes in an experiment.

## Propagation constant

The propagation constant of a sinusoidal electromagnetic wave is a measure of the change undergone by the amplitude and phase of the wave as it propagates in a given direction.

## Quantum mechanics

Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.

## Racemic mixture

In chemistry, a racemic mixture, or racemate, is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule.

Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects.

A beam of light has radial polarization if at every position in the beam the polarization (electric field) vector points towards the centre of the beam.

Radiation pressure is the pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field.

Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width.

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.

## Rasmus Bartholin

Rasmus Bartholin (Latinized: Erasmus Bartholinus; 13 August 1625 &ndash; 4 November 1698) was a Danish scientist, physician and grammarian.

## Ray (optics)

In optics a ray is an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow.

## Rayleigh scattering

Rayleigh scattering (pronounced), named after the British physicist Lord Rayleigh (John William Strutt), is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.

## Rayleigh sky model

The Rayleigh sky model describes the observed polarization pattern of the daytime sky.

## Real number

In mathematics, a real number is a value of a continuous quantity that can represent a distance along a line.

## RealD

RealD Inc. is the company that develops the RealD 3D technology, used for projecting films in stereoscopic 3D using circularly polarized light.

## Refractive index

In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium.

## Right-hand rule

In mathematics and physics, the right-hand rule is a common mnemonic for understanding orientation conventions for the vector cross product in three dimensions.

## Rotation (mathematics)

Rotation in mathematics is a concept originating in geometry.

## S-wave

In seismology, S-waves, secondary waves, or shear waves (sometimes called an elastic S-wave) are a type of elastic wave, and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves.

## Satellite television

Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location.

## Scattering

Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass.

## Seismology

Seismology (from Ancient Greek σεισμός (seismós) meaning "earthquake" and -λογία (-logía) meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies.

## Seven-segment display

A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.

## Shear stress

A shear stress, often denoted by (Greek: tau), is the component of stress coplanar with a material cross section.

## Silver screen

A silver screen, also known as a silver lenticular screen, is a type of projection screen that was popular in the early years of the motion picture industry and passed into popular usage as a metonym for the cinema industry.

## Sir George Stokes, 1st Baronet

Sir George Gabriel Stokes, 1st Baronet, (13 August 1819 – 1 February 1903), was an Irish physicist and mathematician.

## Skywave

In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere.

## Solid

Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma).

## Sound

In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.

## Spectral density

The power spectrum S_(f) of a time series x(t) describes the distribution of power into frequency components composing that signal.

## Spectral theorem

In mathematics, particularly linear algebra and functional analysis, a spectral theorem is a result about when a linear operator or matrix can be diagonalized (that is, represented as a diagonal matrix in some basis).

## Speed of light

The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.

## Spherical coordinate system

In mathematics, a spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its polar angle measured from a fixed zenith direction, and the azimuth angle of its orthogonal projection on a reference plane that passes through the origin and is orthogonal to the zenith, measured from a fixed reference direction on that plane.

## Spin (physics)

In quantum mechanics and particle physics, spin is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei.

## Spin angular momentum of light

The spin angular momentum of light (SAM) is the component of angular momentum of light that is associated with the quantum spin and the wave's circular or elliptical polarization.

## Squid

Squid are cephalopods of the two orders Myopsida and Oegopsida, which were formerly regarded as two suborders of the order Teuthida, however recent research shows Teuthida to be paraphyletic.

## Star

A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.

## Statistics

Statistics is a branch of mathematics dealing with the collection, analysis, interpretation, presentation, and organization of data.

## Stereoscopy

Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.

## Stochastic

The word stochastic is an adjective in English that describes something that was randomly determined.

## Stokes parameters

The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation.

## String (music)

A string is the vibrating element that produces sound in string instruments such as the guitar, harp, piano (piano wire), and members of the violin family.

## Sun

The Sun is the star at the center of the Solar System.

## Sunglasses

Sunglasses or sun glasses (informally called shades) are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes.

## Sunstone (medieval)

The sunstone (sólarsteinn) is a type of mineral attested in several 13th–14th century written sources in Iceland, one of which describes its use to locate the sun in a completely overcast sky.

## Surface wave

In physics, a surface wave is a mechanical wave that propagates along the interface between differing media.

Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when charged particles are accelerated radially, i.e., when they are subject to an acceleration perpendicular to their velocity.

## Telecommunication

Telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems.

## Tensor

In mathematics, tensors are geometric objects that describe linear relations between geometric vectors, scalars, and other tensors.

Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter.

## Thin film

A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness.

## Thin-film interference

Thin-film interference is a natural phenomenon in which light waves reflected by the upper and lower boundaries of a thin film interfere with one another, either enhancing or reducing the reflected light.

## Toughened glass

Toughened or tempered glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass.

## Transverse mode

A transverse mode of electromagnetic radiation is a particular electromagnetic field pattern of radiation measured in a plane perpendicular (i.e., transverse) to the propagation direction of the beam.

## Transverse wave

A transverse wave is a moving wave that consists of oscillations occurring perpendicular (right angled) to the direction of energy transfer (or the propagation of the wave).

## Turnstile antenna

A turnstile antenna, or crossed-dipole antenna, is a radio antenna consisting of a set of two identical dipole antennas mounted at right angles to each other and fed in phase quadrature; the two currents applied to the dipoles are 90° out of phase.

## Twilight

Twilight on Earth is the illumination of the lower atmosphere when the Sun itself is not directly visible because it is below the horizon.

## Unitary matrix

In mathematics, a complex square matrix is unitary if its conjugate transpose is also its inverse—that is, if where is the identity matrix.

## Vacuum

Vacuum is space devoid of matter.

## Vikings

Vikings (Old English: wicing—"pirate", Danish and vikinger; Swedish and vikingar; víkingar, from Old Norse) were Norse seafarers, mainly speaking the Old Norse language, who raided and traded from their Northern European homelands across wide areas of northern, central, eastern and western Europe, during the late 8th to late 11th centuries.

## Watt

The watt (symbol: W) is a unit of power.

## Wave

In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport.

## Wave impedance

The wave impedance of an electromagnetic wave is the ratio of the transverse components of the electric and magnetic fields (the transverse components being those at right angles to the direction of propagation).

## Wave vector

In physics, a wave vector (also spelled wavevector) is a vector which helps describe a wave.

## Waveguide

A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting expansion to one dimension or two.

## Wavenumber

In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance.

## Waveplate

A waveplate or retarder is an optical device that alters the polarization state of a light wave travelling through it.

## Whip antenna

A whip antenna is an antenna consisting of a straight flexible wire or rod.

## Yagi–Uda antenna

A Yagi&ndash;Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods.

## 2018

2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.

## 2019

2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.

## 3D film

A three-dimensional stereoscopic film (also known as three-dimensional sangu, 3D film or S3D film) is a motion picture that enhances the illusion of depth perception, hence adding a third dimension.

## References

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