Timeline of electromagnetism and classical optics
Encyclopedia
Timeline
Timeline
A timeline is a way of displaying a list of events in chronological order, sometimes described as a project artifact . It is typically a graphic design showing a long bar labeled with dates alongside itself and events labeled on points where they would have happened.-Uses of timelines:Timelines...

 of electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 and classical optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...

  • 424 BC Aristophanes
    Aristophanes
    Aristophanes , son of Philippus, of the deme Cydathenaus, was a comic playwright of ancient Athens. Eleven of his forty plays survive virtually complete...

     "lens" is a glass globe filled with water.(Seneca
    Seneca the Younger
    Lucius Annaeus Seneca was a Roman Stoic philosopher, statesman, dramatist, and in one work humorist, of the Silver Age of Latin literature. He was tutor and later advisor to emperor Nero...

     says that it can be used to read letters no matter how small or dim)
  • 4th century BC Mo Di
    Mozi
    Mozi |Lat.]] as Micius, ca. 470 BC – ca. 391 BC), original name Mo Di , was a Chinese philosopher during the Hundred Schools of Thought period . Born in Tengzhou, Shandong Province, China, he founded the school of Mohism, and argued strongly against Confucianism and Daoism...

     first mentions the camera obscura
    Camera obscura
    The camera obscura is an optical device that projects an image of its surroundings on a screen. It is used in drawing and for entertainment, and was one of the inventions that led to photography. The device consists of a box or room with a hole in one side...

    , a pin-hole camera.
  • 3rd century BC Euclid
    Euclid
    Euclid , fl. 300 BC, also known as Euclid of Alexandria, was a Greek mathematician, often referred to as the "Father of Geometry". He was active in Alexandria during the reign of Ptolemy I...

     is the first to write about reflection and refraction and notes that light travels in straight lines
  • 130 AD. — Claudius Ptolemy
    Ptolemy
    Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

     (in his work Optics) wrote about the properties of light
    Light
    Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

     including: reflection
    Reflection (physics)
    Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...

    , refraction
    Refraction
    Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

    , and color
    Color
    Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

     and tabulated angle
    Angle
    In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...

    s of refraction
    Refraction
    Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

     for several media
  • 1021 — Ibn al-Haytham (Alhazen) writes the Book of Optics
    Book of Optics
    The Book of Optics ; ; Latin: De Aspectibus or Opticae Thesaurus: Alhazeni Arabis; Italian: Deli Aspecti) is a seven-volume treatise on optics and other fields of study composed by the medieval Muslim scholar Alhazen .-See also:* Science in medieval Islam...

    , studying vision
    Visual perception
    Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

    .
  • 1269 — Pierre de Maricourt describes magnetic pole
    Magnet
    A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...

    s and remarks on the nonexistence of isolated magnetic poles
    Magnetic monopole
    A magnetic monopole is a hypothetical particle in particle physics that is a magnet with only one magnetic pole . In more technical terms, a magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring...

  • 1305 — Dietrich von Freiberg uses crystalline spheres and flasks filled with water to study the reflection
    Reflection (physics)
    Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...

     and refraction in raindrops that leads to primary and secondary rainbow
    Rainbow
    A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc...

    s
  • 1600 — Dutchman Sacharias Jansen invents a single-lens microscope.
  • 1604 — Johannes Kepler
    Johannes Kepler
    Johannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...

     describes how the eye
    Human eye
    The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

     focuses light
    Light
    Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

  • 1604 — Johann Kepler specifies the laws of the rectilinear propagation of light
  • 1611 — Marko Dominis discusses the rainbow in De Radiis Visus et Lucis
  • 1611 — Johannes Kepler discovers total internal reflection
    Total internal reflection
    Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is...

    , a small-angle refraction law, and thin lens
    Lens (optics)
    A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...

     optics,
  • 1621 — Willebrord van Roijen Snell states his Snell's law
    Snell's law
    In optics and physics, Snell's law is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water and glass...

     of refraction
  • 1630 — Cabaeus finds that there are two types of electric charge
    Electric charge
    Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...

    s
  • 1637 — René Descartes
    René Descartes
    René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

     quantitatively derives the angles at which primary and secondary rainbows are seen with respect to the angle of the Sun
    Sun
    The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

    's elevation
  • 1657 — Pierre de Fermat
    Pierre de Fermat
    Pierre de Fermat was a French lawyer at the Parlement of Toulouse, France, and an amateur mathematician who is given credit for early developments that led to infinitesimal calculus, including his adequality...

     introduces the principle of least time
    Fermat's principle
    In optics, Fermat's principle or the principle of least time is the principle that the path taken between two points by a ray of light is the path that can be traversed in the least time. This principle is sometimes taken as the definition of a ray of light...

     into optics
  • 1665 — Francesco Maria Grimaldi
    Francesco Maria Grimaldi
    Francesco Maria Grimaldi was an Italian Jesuit priest, mathematician and physicist who taught at the Jesuit college in Bologna....

     highlights the phenomenon of diffraction
    Diffraction
    Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...

  • 1673 — Ignace Pardies provides a wave explanation for refraction of light
  • 1675 — Isaac Newton
    Isaac Newton
    Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

     delivers his theory of light
  • 1676 — Olaus Roemer measures the speed of light
    Speed of light
    The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

     by observing Jupiter
    Jupiter
    Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

    's moon
    Natural satellite
    A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

    s
  • 1678 — Christiaan Huygens states his principle of wavefront sources,
  • 1704 — Isaac Newton
    Isaac Newton
    Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

     publishes Opticks
    Opticks
    Opticks is a book written by English physicist Isaac Newton that was released to the public in 1704. It is about optics and the refraction of light, and is considered one of the great works of science in history...

    , a corpuscular theory of light and colour
  • 1728 — James Bradley
    James Bradley
    James Bradley FRS was an English astronomer and served as Astronomer Royal from 1742, succeeding Edmund Halley. He is best known for two fundamental discoveries in astronomy, the aberration of light , and the nutation of the Earth's axis...

     discovers the aberration
    Aberration of light
    The aberration of light is an astronomical phenomenon which produces an apparent motion of celestial objects about their real locations...

     of starlight and uses it to determine that the speed of light
    Speed of light
    The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

     is about 283,000 km
    Kilometre
    The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...

    /s
    Second
    The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....

  • 1746 — Leonhard Euler
    Leonhard Euler
    Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...

     develops the wave theory of light refraction and dispersion
  • 1752 — Benjamin Franklin
    Benjamin Franklin
    Dr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...

     shows that lightning
    Lightning
    Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

     is electricity
    Electricity
    Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

    ,
  • 1767 — Joseph Priestley
    Joseph Priestley
    Joseph Priestley, FRS was an 18th-century English theologian, Dissenting clergyman, natural philosopher, chemist, educator, and political theorist who published over 150 works...

     proposes an electrical inverse-square law
  • 1785 — Charles Coulomb
    Charles-Augustin de Coulomb
    Charles-Augustin de Coulomb was a French physicist. He is best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion. The [SI unit] of charge, the coulomb, was named after him....

     introduces the inverse-square law of electrostatics
    Coulomb's law
    Coulomb's law or Coulomb's inverse-square law, is a law of physics describing the electrostatic interaction between electrically charged particles. It was first published in 1785 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism...

  • 1786 — Luigi Galvani
    Luigi Galvani
    Luigi Aloisio Galvani was an Italian physician and physicist who lived and died in Bologna. In 1791, he discovered that the muscles of dead frogs legs twitched when struck by a spark...

     discovers "animal electricity" and postulates that animal bodies are storehouses of electricity,
  • 1800 — William Herschel
    William Herschel
    Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...

     discovers infrared radiation from the Sun
  • 1801 — Johann Ritter
    Johann Wilhelm Ritter
    Johann Wilhelm Ritter was a German chemist, physicist and philosopher. He was born in Samitz near Haynau in Silesia , and died in Munich.-Life and work:...

     discovers ultraviolet radiation from the Sun
  • 1801 — Thomas Young
    Thomas Young (scientist)
    Thomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...

     demonstrates the wave nature of light and the principle of interference
  • 1802 — Gian Domenico Romagnosi
    Gian Domenico Romagnosi
    Gian Domenico Romagnosi was an Italian philosopher, economist and jurist.-Biography:Gian Domenico Romagnosi was born in Salsomaggiore Terme....

     notes that a nearby voltaic pile
    Voltaic pile
    A voltaic pile is a set of individual Galvanic cells placed in series. The voltaic pile, invented by Alessandro Volta in 1800, was the first electric battery...

     deflects a magnetic needle. His account is largely overlooked.
  • 1808 — Etienne-Louis Malus
    Étienne-Louis Malus
    - External links :...

     discovers polarization by reflection
  • 1809 — Etienne-Louis Malus publishes the law of Malus which predicts the light intensity transmitted by two polarizing sheets
  • 1811 — François Jean Dominique Arago discovers that some quartz crystals continuously rotate the electric vector of light
  • 1816 — David Brewster
    David Brewster
    Sir David Brewster KH PRSE FRS FSA FSSA MICE was a Scottish physicist, mathematician, astronomer, inventor, writer and university principal.-Early life:...

     discovers stress birefringence
    Birefringence
    Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...

  • 1818 — Simeon Poisson predicts the Poisson-Arago bright spot
    Arago spot
    In optics, an Arago spot, Fresnel bright spot, or Poisson spot is a bright point that appears at the center of a circular object's shadow due to Fresnel diffraction...

     at the center of the shadow of a circular opaque obstacle
  • 1818 — François Jean Dominique Arago verifies the existence of the Poisson-Arago bright spot
  • 1820 — Hans Christian Ørsted
    Hans Christian Ørsted
    Hans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...

     notices that a current in a wire can deflect a compass
    Compass
    A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

     needle
  • 1825 — Augustin Fresnel phenomenologically explains optical activity by introducing circular birefringence
  • 1826 — Georg Simon Ohm
    Georg Ohm
    Georg Simon Ohm was a German physicist. As a high school teacher, Ohm began his research with the recently-invented electrochemical cell, invented by Italian Count Alessandro Volta. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential...

     states his Ohm's law
    Ohm's law
    Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...

     of electrical resistance
    Electrical resistance
    The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

  • 1831 — Michael Faraday
    Michael Faraday
    Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

     states his law
    Faraday's law of induction
    Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

     of induction
  • 1833 — Heinrich Lenz
    Heinrich Lenz
    Heinrich Friedrich Emil Lenz was a Russian physicist of Baltic German ethnicity. He is most noted for formulating Lenz's law in electrodynamics in 1833....

     states that an induced current in a closed conducting loop will appear in such a direction that it opposes the change that produced it (Lenz's law
    Lenz's law
    Lenz's law is a common way of understanding how electromagnetic circuits must always obey Newton's third law and The Law of Conservation of Energy...

    )
  • 1845 — Michael Faraday
    Michael Faraday
    Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

     discovers that light propagation in a material can be influenced by external magnetic field
    Magnetic field
    A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

    s (Faraday effect
    Faraday effect
    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...

    )
  • 1849 — Hippolyte Fizeau
    Hippolyte Fizeau
    Armand Hippolyte Louis Fizeau was a French physicist.-Biography:Fizeau was born in Paris. His earliest work was concerned with improvements in photographic processes. Following suggestions by François Arago, Léon Foucault and Fizeau collaborated in a series of investigations on the interference of...

     and Jean-Bernard Foucault measure the speed of light to be about 298,000 km/s
  • 1852 — George Gabriel Stokes
    George Gabriel Stokes
    Sir George Gabriel Stokes, 1st Baronet FRS , was an Irish mathematician and physicist, who at Cambridge made important contributions to fluid dynamics , optics, and mathematical physics...

     defines the Stokes parameters
    Stokes parameters
    The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation. They were defined by George Gabriel Stokes in 1852, as a mathematically convenient alternative to the more common description of incoherent or partially polarized radiation in terms of its...

     of polarization
  • 1864 — James Clerk Maxwell
    James Clerk Maxwell
    James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

     publishes his papers on a dynamical theory of the electromagnetic field
    Electromagnetic field
    An electromagnetic field is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction...

  • 1871 — Lord Rayleigh discusses the blue sky law and sunsets (Rayleigh scattering
    Rayleigh scattering
    Rayleigh scattering, named after the British physicist Lord Rayleigh, is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. The particles may be individual atoms or molecules. It can occur when light travels through...

    )
  • 1873 — James Clerk Maxwell
    James Clerk Maxwell
    James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

     states that light is an electromagnetic phenomenon
  • 1875 — John Kerr
    John Kerr (physicist)
    John Kerr FRS was a Scottish physicist and a pioneer in the field of electro-optics. He is best known for the discovery of what is now called the Kerr effect.-Life and work:...

     discovers the electrically induced birefringence of some liquids
  • 1879 — Jožef Stefan
    Joseph Stefan
    Joseph Stefan was a physicist, mathematician, and poet of Slovene mother tongue and Austrian citizenship.- Life and work :...

     discovers the Stefan-Boltzmann radiation law of a black body
    Black body
    A black body is an idealized physical body that absorbs all incident electromagnetic radiation. Because of this perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum...

     and uses it to calculate the first sensible value of the temperature of the Sun's surface to be 5700 K
    Kelvin
    The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

  • 1888 — Heinrich Rudolf Hertz
    Heinrich Rudolf Hertz
    Heinrich Rudolf Hertz was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell...

     discovers radio wave
    Radio Wave
    Radio Wave may refer to:*Radio frequency*Radio Wave 96.5, a radio station in Blackpool, UK...

    s
  • 1895 — Wilhelm Conrad Röntgen
    Wilhelm Conrad Röntgen
    Wilhelm Conrad Röntgen was a German physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range today known as X-rays or Röntgen rays, an achievement that earned him the first Nobel Prize in Physics in 1901....

     discovers X-ray
    X-ray
    X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

    s
  • 1896 — Arnold Sommerfeld
    Arnold Sommerfeld
    Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...

     solves the half-plane diffraction
    Diffraction
    Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...

     problem
  • 1900 — The Liénard–Wiechert potentials are introduced as time-dependent (retarded) electrodynamic potentials
  • 1905 — Albert Einstein
    Albert Einstein
    Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

     demonstrates that Maxwell's Equations
    Maxwell's equations
    Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

     are not required to describe electromagnetic radiation if Special Relativity
    Special relativity
    Special relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...

     is taken into account
  • 1919 — Albert Michelson makes the first interferometric measurements of stellar diameters at Mount Wilson Observatory
    Mount Wilson Observatory
    The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...

     (see history of astronomical interferometry)
  • 1946 — Martin Ryle
    Martin Ryle
    Sir Martin Ryle was an English radio astronomer who developed revolutionary radio telescope systems and used them for accurate location and imaging of weak radio sources...

     and Vonberg build the first two-element astronomical radio interferometer (see history of astronomical interferometry)
  • 1953 — Charles H. Townes, James P. Gordon, and Herbert J. Zeiger produce the first maser
    Maser
    A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. Historically, “maser” derives from the original, upper-case acronym MASER, which stands for "Microwave Amplification by Stimulated Emission of Radiation"...

  • 1956 — R. Hanbury-Brown and R.Q. Twiss
    Hanbury-Brown and Twiss effect
    The Hanbury Brown and Twiss effect is any of a variety of correlation and anti-correlation effects in the intensities received by two detectors from a beam of particles. HBT effects can generally be attributed to the dual wave-particle nature of the beam, and the results of a given experiment...

     complete the correlation interferometer
  • 1960 — Theodore Maiman produces the first working laser
    Laser
    A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

  • 1966 — Jefimenko
    Oleg D. Jefimenko
    Oleg Dmitrovich Jefimenko - physicist and Professor Emeritus at West Virginia University.-Biography:...

     introduces time-dependent (retarded) generalizations of Coulomb's law and the Biot-Savart law
    Jefimenko's equations
    In electromagnetism, Jefimenko's equations describe the behavior of the electric and magnetic fields in terms of the charge and current distributions at retarded times....

  • 1999 — M. Henny and others demonstrate the Fermionic Hanbury Brown and Twiss Experiment
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