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Central Events in Physics

Source: Human Accomplishment by Charles Murray, pp 179-187

-260GreeceArchimedes discovers the principle of buoyance, leading to the concept of specific gravity.
1025ArabiaAlhazen's Opticae Thesaurus discusses the properties of lenses, the nature of refraction and reflection, and correctly states that the object seen is the source of light rays.
1269FrancePeter Peregrinus' Epistola de Magnete identifies magnetic poles, also representing an early, unsophisticated use of the experimental method.
1583ItalyGalileo discovers that a pendulum's period of oscillation is independent of its amplitude.
1583NetherlandsSimon Stevin introduces the theory of static equilibrium, founding hydrostatics.
1586NetherlandsSimon Stevin presents evidence that falling bodies fall at the same rate.
1589ItalyGalileo's tests of falling bodies represent a landmark use of experimental data.
1592ItalyGalileo invents the thermometer (precisely, barothermometer).
1600EnglandWilliam Gilbert's De Magnete, Magnetisque Corporibus, et de Magno Magnete Tellure describes the magnetic properties of the earth and founds the scientific study of electricity.
1604ItalyGalileo discovers that a free-falling body increases its distance as the square of the time, a pioneering mathematization of a physical phenomenon.
1609NetherlandsZacharias Jansen and Hans Lippershey invent the compound microscope.
1621NetherlandsWillebrord Snell discovers Snell's Law for computing the refraction of light, later discovered independently by Descartes.
1638ItalyGalileo's Discoursi e Dimostrazioni Matematiche, Intorno à Due Nuove Scienze founds modern mechanics.
1643ItalyEvangelista Torricelli invents the barometer in the process of discovering air pressure, and creates the first (near) vacuum known to science.
1645GermanyOtto von Guericke discovers that, in a vacuum, sound does not travel, fire is extinguished, and animals stop breathing.
1648FranceBlaise Pascal states Pascal's principle, that pressure on an enclosed fluid is transmitted without reduction throughout the fluid, founding hydraulics.
1650GermanyOtto von Guericke demonstrates the force of air pressure, using teams of horses to try to pull apart metal hemispheres held together by a partial vacuum.
1665EnglandRobert Hooke's Micrographia introduces the first major challenge to the concept of light as a stream of particles, arguing instead that light is a vibration.
1665ItalyFrancesco Grimaldi gives the first major account of light diffraction and interference.
1669DenmarkErasmus Bartholin describes double refraction, the apparent doubling of images when seen through a crystal.
1670NetherlandsChristiaan Huygens develops a wave theory of light, published in 1690
1672EnglandIsaac Newton describes the light spectrum, and discovers that white light is made from a mixture of colors.
1675FranceOle Rømer deduces that light has a speed and calculates an approximation of it (put at 141,000 miles per second).
1687EnglandIsaac Newton's Philosophiae Naturalis Principia Mathematica states the law of universial gravitation, and the laws of motion, and predicts that the shape of the earth is nonspherical, based on the finding that gravity at Cayenne is less than that a Paris.
1701FranceJoseph Sauveur describes the production of tones by the vibration of strings and coins the word acoustic.
1704EnglandIsaac Newton's Opticks: A Treatise of the Reflections, Refractions, Inflections, and Colours of Light discusses optical phenomena, including the suggestion that light is particulate in nature.
1714NetherlandsDaniel Fahrenheit invents the Fahrenheit scale, and the mercury thermometer, the first accurate thermometer.
1728EnglandJames Bradley discovers the aberration of starlight, leading to a better measure of the speed of light and providing evidence for a heliocentric solar system.
1733FranceCharles DuFay discovers that there are two types of static electric charges and that like charges repel each other while unlike charges attract, linking electricity to magnetism.
1738SwitzerlandDaniel Bernoulli's Hydrodynamica states Bernoulli's Principle and founds the mathematical study of fluid flow and the kinetic theory of gases.
1742SwedenAnders Celsius invents the Celsius scale.
Ewald von Kleist and Pieter van Musschenbroek independently invent a practical device for storing an electric charge, the Leyden jar.
1748FranceJean Nollet discovers osmosis, the passage of a solution through a semi-permeable membrane separating two solutions with different concentrations.
1752USABenjamin Franklin discovers that lightning is a form of electricity.
1762ScotlandJoseph Black develops the concept of latent heat, the quantity of heat absorbed or released when a substance changes its physical phase at constant temperature.
1787FranceJacques Charles demonstrates that different gases expand by the same amount for a given rise in temperature, known both as Charles' law and Gay-Lussac's law (Joseph Gay-Lussac is the first to publish, in 1802. The relationship was first stated a century earlier by Guillaume Amontons, then forgotten).
1798EnglandHenry Cavendish and Nevil Maskelyne measure the gravitational constant, leading to an accurate estimate of the mass of the earth.
1798GermanyBenjamin Thompson (Count Rumford) demonstrates that heat is a form of motion (energy) rather than a substance.
1800EnglandWilliam Herschel discovers infrared radiation, and that invisible light beyond the red produces the most heat.
1801EnglandThomas Young uses diffraction and interference patterns to demonstrate that light has wavelike characteristics.
1808FranceÉtienne Malus discovers the polarization of light.
1815FranceJean Biot discovers that the plane of polarized light is twisted in different directions by different organic liquids.
1818FranceAugustin Fresnel's Mémoire sur la Diffraction de la Lumière demonstrates the ability of a transverse wave theory of light to account for a variety of optical phenomena, converting many scientists to a wave theory.
1820DenmarkHans Ørsted emonstrates that electricity and magnetism are related, jointly (with Ampère) founding the science of electrodynamics.
1820GermanyJohann Schweigger invents the needle galvanometer, later essential for the telegraph.
1821EnglandMichael Faraday's "On Some New Electromagnetic Motions" reports his discovery that electrical forces can produce motion and describes the principle of the electric motor.
1822FranceJean Fourier's Théorie Analytique de la Chaleur applies Fourier's theorem to the study of heat flow, an influential application of mathematics to physical phenomena.
1822GermanyThomas Seebeck discovers that two different metals will generate electricity if their points of juncture are maintained at different temperatures, the Seebeck effect, and demonstrates thermoelectricity.
1823EnglandWilliam Sturgeon invents the electromagnet.
1824FranceNicolas Carnot's Réflexions sur la Puissance Motrice du Feu is the first scientific analysis of steam engine efficiency, founding thermodynamics.
1827FranceAndre Ampère publishes Ampere's Law, a mathematical expression of Ørsted's relationship between magnetism and electricity.
1827GermanyGeorge Ohm publishes Ohm's Law, that an electrical current is equal to the ratio of the voltage to the resistance, a founding event in electrical engineering.
1827ScotlandRobert Brown discovers continuous random movement of microscopic solid particles when suspended in a fluid, later known as Brownian motion.
1829ScotlandWilliam Nicol invents the Nicol prism for measuring the degree of twist in a plane of polarized lead, founding polarimetry.
1829USAJoseph Henry uses insulated wire to create an electromagnet able to lift a ton of iron.
Michael Faraday and Joseph Henry independently discover that a changing magnetic force can generate electricity, the phenomenon of electromagnetic induction.
1832EnglandMichael Faraday discovers the basic laws of electrolysis that govern the production of a chemical reaction by passing electric current through a liquid or solution.
1834FranceJean Peltier discovers the Peltier effect, that a current flowing across a junction of two dissimilar metals causes heat to be absorbed or freed, depending on the direction in which the current is flowing.
1839FranceAlexandre Becquerel discovers the photovoltaic effect, whereby light can be used to induce chemical reactions that produce an electric current.
1842GermanyChristian Doppler discovers the Doppler effect, that the frequency of waves emitted by a moving source changes when the source moves relative to the observer.
1842GermanyJulius von Mayer and Carl Mohr develop early formulations of the concept of conservation of energy.
1843EnglandJames Joule discovers Joule's first law, describing the heat produced hwen an electric current flows through resistance for a given time.
1847GermanyHermann von Hemholtz states the law of conservation of energy, the first law of thermodynamics: in an isolated system, the total amount of energy does not change.
1848ScotlandWilliam Thomson (Baron Kelvin) defines absolute zero and proposes the Kelvin scale.
1849FranceArmand-Hippolyte-Louis Fizeau and Jean-Bernard-Léon Foucault determine the speed of light to within less than one percent error.
1850EnglandGeorge Stokes discovers the terminal velocity of objects falling through viscous liquid.
1850GermanyRudolf Clausius discovers the second law of thermodynamics, that the disorder of a closed system increases with time.
1851FranceJean-Bernard-Léon Foucault demonstrates the rotation of the earth with the Foucault pendulum.
1852EnglandJames Joule and William Thomson discover the Joule-Thomson effect, which later permits liquefaction of some permanent gases.
Johann Geissler invents Geissler tubes, producing a better vacuum. As improved by William Crookes, the tubes produce cathode rays, leading to discovery of the electron.
1865ScotlandJames Maxwell's "A Dynamical Theory of the Electromagnetic Field" presents Maxwell's equations describing the behavior of electric and magnetic fields and proposes that light is electromagnetic in character, constituting the first theoretical unification of physical phenomena.
1873ScotlandJames Maxwell's A Treatise on Electricity and Magnetism elaborates the mathematical model of electromagnetic waves, predicting such phenomena as radio waves and pressure caused by light rays.
1875EnglandWilliam Crookes invents the radiometer, thereby providing support for the kinetic theory of gases.
1876GermanyEugen Goldstein discovers cathode rays, streams of fluorescence flowing from the negatively charged cathode in an evacuated tube.
1876USAJosiah Gibbs publishes the first of a series of papers applying thermodynamics to chemical hange, defining the concepts of free energy, chemical potential, equilibrium between phases of matter, and the phase rule, thereby establishing general principles of physical chemistry.
1879AustriaJosef Stefan discovers Stefan's Law, that the radiation of a body is proportional to the fourth power of its absolute temperature.
1880FrancePierre and Jacques Curie discover that ultrasonic vibrations are produced by piezoelectricity.
1883USAThomas Edison discovers the Edison effect, later a major factor in the invention of the vacuum tube.
1886GermanyHeinrich Hertz produces radio waves in the laboratory, confirming Maxwell's electromagnetic theory and laying the basis for radio, television, and radar.
1887USAAlbert Michelson and Edward Morley fail to confirm the existance of ether and demonstrate that the speed of light is a constant, raising questions about the adequacy of classical physics.
1888GermanyEugen Goldstein discovers canal rays, from cathode rays.
1892IrelandGeorge Fitzgerald hypothesizes the Fitzgerald contraction, that distance contracts with speed, accounting for the results of the Michelson-Morley experiment.
1892RussiaKonstantin Tsiolkovsky begins theoretical work on rocket propulsion and space flight.
1892ScotlandJames Dewar invents the Dewar flask.
1895GermanyWilhelm Röntgen discovers X-rays.
1895NetherlandsHendrik Antoon Lorentz extends Fitzgerald's work, hypothesizing that mass also increases with velocity, leading to the conclusion that the speed of light is a universal maximum.
1895ScotlandCharles Wilson invents the cloud chamber, which later becomes an indispensable tool in the study of atomic particles.
1896FranceAntoine Becquerel discovers spontaneous radioactivity.
1896NetherlandsPieter Zeeman discovers the splitting of lines in a spectrum when the spectrum's source is exposed to a magnetic field, the Zeeman effect, later used to study the fine details of atomic structure.
1897EnglandJ.J. Thomson discovers the first subatomic particle, the electron.
1897FranceMarie and Pierre Curie demonstrate that uranium radiation is an atomic phenomenon, not a molecular phenomenon, and coin the word radioactivity.
1899EnglandErnest Rutherford discovers two types of uranium radiation, alpha rays (massive and positively charged) and beta rays (lighter and negatively charged).
1900FranceAntoine-Henri Becquerel demonstrates that the process of radioactivity consists partly of particles identical to the electron.
1900GermanyMax Planck discovers Planck's Law of black body radiation, introducing Planck's constant and the concept that energy is radiated in discrete packets called quanta, founding quantum physics.
1902EnglandErnest Rutherford and Frederick Soddy demonstrates that uranium and thorium break down into a series of radioactive intermediate elements.
1904EnglandJ.J. Thomson proposes the "plum-pudding" model of the atom in which electrons are embedded in a sphere of positive electricity.
1905SwitzerlandAlbert Einstein's "Zur Elektrodynamik bewegter Körpen" introduces the special theory of relativity, that the assumption that light is quantized can explain the photoelectric effect, deduces as a consequence of the special theory of relativity that the mass of a body is a measure of its energy content, expressed as E=mc2, and explains Brownian motion mathematically, the most convincing evidence to date for the existence of molecules and atoms, and proposes a method to deduce the size of molecules and atoms.
1906GermanyHermann Nernst states the third law of thermodynamics, that all bodies at absolute zero would have the same entropy, though absolute zero cannot be perfectly attained.
1908EnglandErnest Rutherford and Johannes Geiger invent an alpha-particle counter.
1908FranceJean Perrin calculates atomic size from Brownian motion.
1911EnglandErnest Rutherford, using using experimental results from Ernst Marsden and Johannes Geiger, proposes the concept of the atomic nucleus, leading to the deduction of the true nature of the atom.
1911NetherlandsHeike Kamerlingh-Onnes discovers superconductivity, the disappearance of electrical resistance in certain substances as they approach absolute zero.
1911USAVictor Hess discovers the phenomenon later called cosmic rays.
1912GermanyMax von Laue develops X-ray diffraction using crystals, founding X-ray crystallography.
1913DenmarkNiels Bohr applies quantum theory to the structure of the atom, describing electron orbits and electron excitation and de-excitation.
1913EnglandFrederick Soddy and Kasimir Fajans discover isotopes, leading to the radioactive displacement law.
1913USARobert Millikan completes experiments determining the charge of an electron, leading to the conclusion that the electron is the fundamental unit of electricity.
1914EnglandHenry Moseley introduces the concept of atomic number, the amount of positive charge, on the nucleus, for classifying atoms.
1914EnglandErnest Rutherford discovers the proton.
1916GermanyAlbert Einstein's general theory of relativity describes space as a curved field modified locally by the existence of mass, replacing Newtonian ideas which invoke a force of gravity, and derives the basic equations for the exchange of energy between matter and radiation.
1919EnglandFrancis Aston invents the mass spectrograph to measure the mass of atoms, and discovers isotopes in non-radioactive elements and states the whole-number rule.
1919EnglandErnest Rutherford uses atomic bombardment to alter atomic nuclei, transforming one element into another and constituting the first nuclear reaction.
1923FranceLouis de Broglie states that every particle should have an associated matter wave whose wavelength is inversely related to the particle's momentum, providing an explanation for the wave-particle duality of light.
1923USAArthur Compton discovers the Compton effect, whereby the wavelength of X-rays and gamma rays increases following collisions with electrons.
1925GermanyWolfgang Pauli develops the exclusion principle stating that in a given atom no two electrons can have the identical set of four quantum numbers.
1926AustriaErwin Schrödinger develops the mathematics of wave mechanics, including the Schrödinger wave equation.
1927EnglandPaul Dirac's relativistically invariant form of the wave equation of the electron unifies aspects of quantum mechanics and relativity theory.
1927GermanyWerner Heisenberg's "On the Intuitive Content of Quantum Kinematics and Mechanics" introduces the uncertainty principle.
1928DenmarkNiels Bohr's "The Philosophical Foundations of Quantum Theory" introduces the principle of complementarity, arguing that different but complementary models may be needed to explain the full range of atomic and subatomic phenomena.
1930EnglandPaul Dirac predicts the existence of antimatter.
1930USANils Edlefsen and Ernest Lawrence invent the cyclotron, an instrument used to produce directed beams of charged particles that transforms research into fine nuclear structure.
1931SwitzerlandWolfgang Pauli predicts the existence of the particle later named the neutrino.
1932EnglandJames Chadwick discovers the neutron.
1932EnglandJohn Cockroft achieves a nuclear reaction by splitting the atomic nucleus.
1932USARobert Millikan and Carl Anderson discover the positron, the first antiparticle.
1933GermanyErnst Ruska and Reinhold Ruedenberg invent an electron microscope that is more powerful than a conventional light microscope.
1934RussiaPavel Cherenkov, Ilya Frank, and Igor Tamm discover and interpret the Cherenkov effect, the wave of light produced by particles apparently moving faster than the speed of light in a medium other than a vacuum.
1934USAEnrico Fermi achieves the first nuclear fission reaction.
1935JapanHideki Yukawa predicts the exitence of mesons as fundamental carriers of the nuclear force field.
1938GermanyOtto Hahn and Friedrich Strassman split an atomic nucleus into two parts by bombarding uranium-235 with neutrons.
1940USAMartin Kamen discovers carbon-14, the most useful of all the radioactive tracers.
1942USAEnrico Fermi, Walter Zinn, and Herbert Anderson achieve the first sustained nuclear reaction.
Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga independently work out the equations of quantum electrodynamics governing the behavior of electrons and electromagnetic reactions generally.
Edwin McMillian and Vladimir Veksler independently invent the synchrotron.
1947EnglandDennis Gabor develops the basic concept of holography, which must wait on the laser for implementation.
1948USAJohn Bardeen, Walter Brattain, and William Shockley discover the transistor effect.