Chronology of PhysicsCollection of major events in the history of

physics

The major source wasIssac Asimov's Biographical Encyclopedia of Science and Technology.

2980 BCEImhotep lives in Egypt, designs step pyramid at Sahara. Many other achievements attributed to him.

1650 BCEAhmose, Egyptian scribe, writes Directions for Attaining Knowledge of All Dark Things, a text which deals with the solutions of many simple equations such as finding volumes and areas.

600 BCEAnaximander introduces sundial to Greece, is first person to attempt to draw map of

world, believes world is made of apeiron, a word meaning infinite.

Thales predicts an eclipse of the moon, generalizes Egyptian geometry, invents deductive mathematics, studies magnetism and states that fundamental material of universe is water.

535 BCEAnaximenes believes air the fundamental element.

520 BCEXenophanes believes earth is the fundamental element and that the mountains were originally covered by the seas.

500 BCEPythagoras flourishes in Greece and southern Italy. Founds mystery cult unique in its emphasis on mathematics, including belief that the whole universe rested on numbers.

Heraclitus says the only permanent thing is change, hence fire is the fundamental element.

Hanno, a Carthaginian, is perhaps the first person to sail around Africa.

450 BCEAnaxagoras believes earth and stars created of identical materials.

420 BCEDemocritus develops first atomic theory.

400 BCEZeno states that the senses are useless as a means of obtaining knowledge and presents a series of paradoxes, all based on fallacies, to prove it.

Hippocrates stresses rationalism, careful observation and honorable standards in the practice of medicine.

350 BCE

Aristotle does much work in many sciences, is most successful in biology. He argues for a spherical Earth using lunar eclipses and other observations. Many of his ideas about physics remain in fashion for almost two thousand years.

300 BCEAristarchus attempts to measure distances from earth to moon and to sun, but large experimental error causes him to be wrong by factor of twenty.

Euclid writes The Elements, still the standard in geometry250 BCE

Archimedes, the greatest scientist of ancient times, develops principles of density, buoyancy, simple machines and computes pi to two decimal places using inscribed and cirumscribed polygons and the area under a parabolic segment.

240 BCE

Eratosthenes, librarian at Alexandria, determines that the Earth is a sphere with a circumference of about 25,000 miles.

200 BCEApollonius writes On Conic Sections and names the ellipse, parabola, and hyperbola.

150 BCEHipparchus invents the astrolabe and uses parallax to determine that the distance to the Moon is roughly 380,000 km.

134 BCEHipparchus creates the magnitude scale of stellar apparent luminosities, discovers the precession of the equinoxes and makes a detailed star map.

50 ADHero, Greek engineer, builds first steam engine and many other devices.

150

Ptolemy places earth at center of universe with planets and sun moving around it. Publishes Megale mathematike syntaxis, generally known as the Almagest, a star catalog.

450Ch'ung-Chih and Keng-Chih compute pi to six decimal places.

750Geber, at height of Arab empire, adds sulfur and mercury to the list of elements.

830Al-khwarizmi introduces zero to west.

1202Fibonacci explains use of Arabic numerals.

1249Bacon writes about convex lens eyeglasses for treating farsightedness

1260

Bacon calculates distance to stars as 130,000,000 miles.

1295Polo returns to Venice after 20 years in China.

1340William of Ockham has a close shave with the Pope, states that "Entities must not needlessly be multiplied" [that is, the simplest theory explaining facts is the correct one.]

1424al-Kashi computes pi to sixteen decimal places using inscribed and circumscribed polygons.

1452da Vinci born; makes many contributions to science and art during his life.

1454

Gutenberg begins publication of the Bible, the first typeset book.

1480da Vinci describes a workable parachute.

Behaim introduces the nautical astrolabe

1492Columbus discovers the New World.

da Vinci describes a flying machine.

1520Ferro develops a method for solving cubic equations.

1521Magellan observes the Magellanic Clouds during his circumnavigating expedition.

1543Copernicus publishes theory of heliocentric solar system.

1569Mercator issues the first Mercator projection map

1572Brahe observes nova, publishes De Nova Stella.

1577Brahe observes comet, parallax studies show it is outside of atmosphere.

1581Galileo discovers period of pendulum independent of amplitude.

1589Galileo uses balls rolling on inclined planes to show that different weights fall with the same acceleration.

1590Janssen invents the microscope.

1593

Galileo invents thermoscope, a crude thermometer but best until 1680's.

1596van Ceulen computes pi to twenty decimal places using inscribed and cirumscribed polygons.

1598Philip II of Spain announces prize for invention of accurate ship chronometer which would aid in navigation.

1600Gilbert publishes De Magnete, shows magnet dips towards pole.

1609Galileo uses telescope to discover mountains on moon, sunspots, satellites of Jupiter, phases of Venus and many new stars.

Kepler publishes Astronomia Nova, states that planets move in ellipses [Kepler's first

law] and that a line connecting a planet to the sun will sweep out equal areas in equal times [Kepler's second law].

1610Galileo sees Saturn's rings but does not recognize that they are rings.

Kepler uses the dark night sky to argue for a finite universe.

1611Kepler discovers total internal reflection, a small angle refraction law, and thin lens optics

1613Galileo uses sunspot observations to demonstrate the rotation of the Sun

Napier publishes first table of logarithms.

1619

Kepler publishes his third law [square of period of revolution proportional to cube of distance].

1620Bacon publishes Novum Organum, argues that laws of science must be induced from experiment.

1621Snell discovers that light moving from rarer to denser medium is bent towards vertical [Snell's Law].

1622Oughtred invents the slide rule.

1632Galileo publishes Dialogue on the Two Chief World Systems, argues in favor of Copernican system.

1633

Galileo tried for heresy, renounces Copernician system, Dialogue banned by Church.

1635Gellibrand publishes finding that compass needle drifts with time.

1637Descartes publishes Discourse on Method, states mechanistic view of universe, introduces use of coordinate system.

1640Bullialdus suggests an inverse-square gravitational force law.

1641Gascoigne invents telescope cross hairs

1642Galileo dies on January 8th.

Newton born on Dec 25th.

1643Torricelli produces vacuum in closed cylinder partially filled with mercury, produces first barometer and shows air has "weight."

1646Pascal confirms Torricellian view, demonstrates pressure of atmosphere decreases with altitude.

1650Guericke constructs first air pump.

Riccioli discovers first double star.

1654Guericke demonstrates the "power of the vacuum" with use of Magdeburg spheres.

Pascal and Fermat create the theory of probability.

1655Cassini discovers Jupiter's great red spot.

1656Huygens builds the first accurate pendulum clock and identifies Saturn's rings as rings and discovers Titan and the Orion Nebula.

1657Fermat introduces the principle of least time into optics

1662Boyle discovers that volume of gas decreases linearly with pressure.

1663Royal Society founded.

1665Newton discovers sunlight can be broken into spectrum by prism.

Grimaldi's work on diffraction of light publishes posthumously.

Cassini determines the rotational speeds of Jupiter, Mars, and Venus.

1666Newton determines that force varying as 1/r^2 would cause planets to move in ellipses.

1668Newton invents reflecting telescope.

Wallis suggests the law of conservation of momentum.1669

Newton appointed Lucasian Professor of Mathematics at Cambridge.

Bartholin discovers double refraction.

1672Guericke reports production of static electric sparks made by rubbing rotating sulfur ball with hand.

Montanari notices that Algol's brightness varies.

1675Romer uses the orbital mechanics of Jupiter's moons to estimate that the speed of light is about 227,000 km/s.

1676Mariotte independently discovers Boyle's Law [P-V behavior of gases].

1678Hooke discovers that restoring force of spring proportional to displacement from equilibrium position [Hooke's Law].

Huygens states his principle of wavefront sources.

1687Newton publishes Philosophiae Naturalis Principia Mathematica, containing the principle of inertia [Newton's First Law], the definition of of force [Newton's Second Law] and the statement that every action has an

equal and opposite reaction [Newton's Third Law].

1690Huygens argues that light is a longitudinal wave.

1693Leibniz states law of the conservation of mechanical energy.

1699Amontons publishes work on P-T behavior of gases.

1700Savery invents "The Miner's Friend", first working steam engine.

1701Halley suggests using the salinity and evaporation of the Mediterranean to determine the age of the Earth.

1704

Newton publishes Opticks.

1705Halley demonstrates the periodicity of certain comets, predicts one will return in 1758.

1706Machin develops a quickly converging inverse-tangent series for pi and computes pi to 100 decimal places.

1707Lack of accurate chronometers causes British fleet to miscalculate its position and crash on rocks off Cornwall.

1712Newcomen invents improved steam engine.

Taylor develops Taylor series.

1713British government announces prize for construction of accurate ships' chronometer which would aid in navigation.

1714Fahrenheit invents mercury thermometer.

1716Halley suggests a high precision measurement of the Sun-Earth distance by timing the transit of Venus.

1728Harrison constructs accurate chronometer, claims prize announced in 1707.

1729Newton's Principia Mathematica published in English.

Gray discovers principle of electrical conduction.

1731Reaumur invents water - alcohol thermometer.

1733

Du Fay studies electrical repulsion, postulates "vitreous electricity" and "resinous electricity", each of which repels itself but is attracted to the other. [demo E1,2,3]

Bradley measures diameter of Jupiter.1737

Voltaire has one of his mistresses translate Newton's Principia into French and writes an appropriate introduction.

1738Bernoulli publishes book on fluid flow, shows that as velocity of fluid increases, its pressure decreases [Bernoulli's Principle].

1742

Celsius proposes temperature scale based on one hundred degrees between freezing and boiling points of water.

1745

Leyden Jar invented at University of Leiden. [demo]

Lomonosov proposes law of conservation of mass [year approximate].

1747Franklin invents lightning rod.

Lind discovers that citrus fruits prevent scurvy.1752

Franklin flies kite during thunderstorm, demonstrates that lightning is a form of electricity.

1756Canton notices effect of aurora borealis on compass needle.

1758Dollond produces achromatic lens.

1759

Halley's comet, due to gravitational effects of Saturn and Jupiter, returns a year later than predicted.

1765Harrison finally awarded prize for design of chronometer.

1766Cavendish announces discovery of hydrogen.

1768Cook observes transit of Venus from island of Tahiti.

1769Watt invents improved steam engine.

1771Galvani notices that muscles of dissected frogs twitch when touched by electric spark.

Messier publishes first list of nebulae.

Priestly discovers that plants convert carbon dioxide into oxygen.

1780Lagrange and Laplace show the heat evolved in the formation of a compound from its elements equals the amount required to decompose compound into its elements.

1781Herschel discovers the planet Uranus

1782Goodricke notices that the brightness variations of Algol are periodic and proposes that it is partially eclipsed by a body moving around it.

1783Watt defines the horsepower as 550 foot-pounds per second.

Montgolfier brothers launch first balloon, it goes 1500 feet upward and a mile and a half downwind in 10 minutes.

Charles constructs first hydrogen filled balloon.

1784Blanchard sails hydrogen balloon across English Channel.

1785Coulomb shows that electrical force varies as 1/r^2. [demo]

1786Chladni uncovers quantitative relationships governing transmission of sound.

Galvani discovers `animal electricity' and postulates that animal bodies are storehouses of electricity.

1787Lavoisier publishes Methods of Chemical Nomenclature.

Charles rediscovers P-T behavior of gases but fails to publish.

1788Lagrange publishes Analytical Mechanics, uses calculus of variations to solve generalized problems in mechanics.

1789Lavoisier publishes Elementary Treatise on Chemistry, first modern chemistry textbook.

1790Fitch launches first practical steamship.

1791Prevost shows that cold does not flow from cool objects to hot ones.

1791Faraday born.

1792Murdock discovers coal gas.

1793Herschel discovers double stars circle one another.

Lagrange, Laplace, Lavoisier and others appointed by rulers of French Revolution to committee for the development of new system of weights and measures.

Whitney invents cotton gin.

1794Lavoisier is guillotined during the French Revolution.

1795Lagrange, Laplace and other survivors announce the metric system.

Gauss invents the method of least squares while still a teenager.

1797

Garnerin demonstrates first use of a parachute.

1798Cavendish measures value of G, the gravitational constant.

Rumford shows that mechanical energy can be converted into heat.

Whitney devises assembly line production of rifles.

1799Laplace begins publication of Celestial Mechanics [finished in 1825].

************************** 1800 *************************************

Volta invents the electric battery.

Herschel discovers infrared light.

Davy discovers nitrous oxide [laughing gas].

1801Young announces cause of astigmatism.

Ritter discovers ultraviolet light.

Piazzi discovers the asteroid Ceres.

Jacquard invents the Jacquard punched card loom.

Fulton builds the first submarine.

1802Gay-Lussac rediscovers P-T behavior of gases and publishes.

Wollaston finds seven dark lines in solar spectrum.

1803Dalton first proposes modern atomic theory.

Young discovers diffraction of light by slits; proposes light is a wave.

Biot announces that stony material falling from skies are meteorites.

1804Rumford marries widow of Lavoisier. They are divorced four years later. Rumford remarks that Lavoisier was lucky to have been guillotined.

Biot shows that earth's magnetism undiminished by altitude but panics during balloon flight.

1806Argand associates vectors with complex numbers and studies complex number operations in geometrical term.

1807Fulton launches the first profitable steamship.

Fourier announces that any periodic oscillation can be broken into a series of simpler regular oscillations.

Davy uses electric current to isolate potassium.

1808Dalton publishes New System of Chemical Philosophy.

1809Lamarck proposes an inheritance of acquired characteristics theory of evolution.

1811Avogadro proposes that at same temperature, equal volumes of gases contain equal number of particles.

1814Fraunhofer discovers hundreds of dark lines in solar spectrum.

Stephenson builds the first practical steam powered railroad locomotive.

1815Biot shows that solutions of organic materials rotate polarized light.

Brewster shows reflection polarizes light.

1816Brewster invents kaleidoscope.

1817Young states that light is a transverse wave.

Pelletier and Caventou isolate chlorophyll.

1818Dulong and Petit find atomic weight and specific heat inversely related.

1820Oersted discovers electric current affects compass needle. [demo]

Ampere, one week later, announces right hand screw rule.

1821Seebeck discovers thermoelectricity.

Faraday builds an electricity-powered motor.

1822Niepce produces first photograph.

Fourier states that a scientific equation must involve a consistent set of units.

Mantell discovers the fossilized skeleton of an iguanodon dinosaur.

1823Ampere postulates tiny electrical currents in iron as source of magnetism.

Faraday liquefies carbon dioxide, chlorine and other gases.

1824Carnot publishes On the Motive Power of Fire, which defines potential energy and demonstrates the maximum efficiency of an engine depends on the temperature difference between the hottest and coldest parts.

1825Stephenson produces first practical steam locomotive.

Faraday discovers benzene.

1826Niepce takes the first permanent photograph.

1827Ohm discovers current directly proportional to voltage, inversely proportional to resistance.

Babinet proposes unit of length be based on a specified wavelength of light.

1828Nicol produces polarized light by use of double refraction.

Berzelius publishes uses modern chemical notation in table of atomic weights.

Sturgeon produces practical electromagnet.

Wohler discovers ammonium cyanate can be converted into urea.

1830Henry, during summer vacation, begins work on magnetic induction. Not quite finished, he plans to complete it the next summer.

1831Maxwell born.

Henry invents an electric telegraph, describes electric motor.

Schwabe discovers Jupiter's great red spot.

Faraday finds that changing magnetic field produces electric current and announces the discovery of magnetic induction. [demo]

Graham finds rate of diffusion of gas inversely proportional to square root of molar weight.

1832Gauss devises logical system of units of magnetism.

Faraday codifies laws of electrolysis.

Henry discovers self-induction.

1833Gauss invents an electric telegraph.

British Association for the Advancement of Science founded.

Lenz finds resistance of metals changes with temperature.

1834Lenz generalizes law of magnetic induction.

Clapeyron presents a formulation of the second law of thermodynamics.

1835Galileo's Dialogue removed from Index of Prohibited Books.

Henry invents electric relay.

Coriolis begins study of motion on a spinning surface (see also)

Morse develops the Morse code.

1836Daniell invents first reliable electric battery.

1837Wheatstone invents an electric telegraph.

Agassiz begins his glaciation studies which eventually demonstrate that the Earth has had at least one Ice Age.

1838Bessel uses parallax method to determine distance from earth to a star - six light years or 35,000,000,000,000 miles.

1839Grove invents electric battery utilizing hydrogen and oxygen.

Goodyear invents vulcanized rubber.

1840Morse patents an electric telegraph using Morse code.

1842Doppler works out relationship relating pitch to relative motion of source and observer.

Mayer presents evidence on the conservation of energy.

1843Schwabe announces that sunspots wax and wane on eleven year cycle.

Joule experimentally finds the mechanical equivalent of heat.

1844Bessel discovers dark companion to Sirius.

1845Rosse discovers spiral galaxies.

Stokes begins work on flow of viscous fluids.

Leverrier observes a 35'' per century excess precession of Mercury's orbit.

1846Weber introduces logical system of electrical units.

Adam and Leverrier independently discover Neptune.

Lassell, within a month, discovers Triton, satellite of Neptune.

Kelvin, from physical principles, calculates age of earth as somewhere between 20 and 400 million years.

1847Boole publishes work The Calculus of Logic on symbolic logic.

Joule publishes work on the conservation of energy.

Helmholtz publishes work on the conservation of energy. (for a different view, check out this)

1848Kelvin proposes that energy of gas is zero at -273 Celsius.

1849Fizeau and Foucault measure the speed of light to be about 298,000 km/s.

1850Clausius begins work on ratio of heat content to temperature.

1851Foucault uses pendulum to show that earth rotates.

1852Otis invents first safe elevator.

Joule and Thompson [Lord Kelvin] announce cooling of gases by expansion.

Foucault invents the gyroscope.

1855Geissler invents mercury vacuum pump.

Balmer devises formula to predict wavelengths of light in hydrogen spectrum.

1856Bessemer invents blast furnace.

Perkin invents the first synthetic dye.

1857Maxwell shows that Saturn's rings must consist of small particles.

1858Darwin and Wallace announce theory of evolution due to natural selection.

1859Carrington discovers solar flares.

Darwin publishes On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life.

Nobel begins manufacture of nitroglycerin.

Plante invents rechargeable battery.

1860Bunsen and Kirchoff invent optical spectroscopy, discover two elements.

Swan invents primitive electric light bulb.

Maxwell begins work on statistical thermodynamics.

1861Graham discovers colloids.

1862Lord Kelvin attempts to find the age of the Earth by examining its cooling time and estimates that the Earth is between 20--400 million years old.

1864Maxwell begins work on electromagnetism, finishes in 1873.

1865Clausius introduces the term entropy.

Mendel publishes his work on genetics in a local journal.

Pasteur announces germ theory of disease.

Kekule proposes ring structure for benzene.

1866Field finances first trans-Atlantic cable.

Kundt studies the velocity of sound in gases.

Schiaparelli realizes that meteor showers occur when the Earth passes through the orbit of a comet that has left debris along its path.

1868Westinghouse patents the air brake.

Janssen discovers helium on sun.

1869

Mendeleev publishes his discovery of chemical periodicity.

Miescher discovers nucleic acids in the nuclei of cells.

1870Meyer publishes his discovery of chemical periodicity.

1871Boltzmann begins work on statistical mechanics.

1872van de Waals publishes work on deviation of real gases from ideal gas law.

1873Maxwell discovers Maxwell equations;

states that light is an electromagnetic phenomenon.

1874van't Hoff and Le Bel advance a three-dimensional stereochemical representation of organic molecules and propose a tetrahedral carbon atom.

Kelvin formally states the second law of thermodynamics.

1875Crookes invents radiometer.

1876Gibbs begins publication of papers on free energy and chemical potential in the Transactions of the Connecticut Academy of Sciences.

Bell patents the telephone.

Otto invents four-stroke internal combustion engine.

1877Cailetet liquefies oxygen and nitrogen.

Edison invents the phonograph.

1879Stokes announces that radiation content of body proportional to fourth power of its absolute temperature.

Edison invents the practical light bulb.

Einstein born.

1880Milne invents the seismograph.

1882Stewart proposes existence of ionosphere.

Ferdinand Lindemann proves that pi is transcendental and that the circle cannot be squared with a compass and straightedge.

1883Maxim invents the machine gun.

Amagat pressurizes gas to 3000 atmospheres.

1885Stanley invents the alternating current transformer.

1886Goldstein demonstrates existence of positive rays in cathode ray tubes.

Mach proposes that all matter is sensation.

1887Michelson and Morley, using interferometry, fail to detect earth's motion through ether.

Hertz detects electromagnetic waves. [1 + 2 x demo]

1888Hertz discovers the photoelectric effect.

1889Edison invents practical motion picture projector.

1891Stoney proposes the name "electron" for carrier of negative charge.

1893Wien finds that blackbody radiation has a peak at intermediate wavelengths but fails to find theory to predict this.

Mach states Mach's principle---first constructive attack on the idea of Newtonian absolute space.

1894

Ramsay and Raleigh discover argon.

1895Roentgen discovers x-rays emitted from cathode ray tube.

Fitzgerald proposes objects shrink in the direction of motion.

Ramsay discovers helium in rocks containing uranium.

Curie [Pierre] discovers materials lose magnetism at certain critical temperature.

1896Nobel dies, wills fortune to establishment of annual prize in Peace, Literature, Physiology, Chemistry and Physics.

Becquerel discovers radioactivity.

Sperry invents gyroscopic compass.

1897

Braun invents the oscilloscope.

Thomson measures e/m of electron.

1898Dewar liquefies hydrogen.

1899

Dewar solidifies hydrogen.

Rutherford discovers that uranium radiation is composed of positively charged alpha particles and negatively charged beta particles.

******************************* 1900 **************************************

Freud publishes The Interpretation of Dreams.

Planck proposes that light is emitted in quanta, explains blackbody radiation.

Villard discovers radiation consists of two types which are bent in different directions by magnetic field.

Sabine uses acoustical principles to design Boston Symphony Hall.

1901Zeeman discovers that source of light in intense magnetic fields produces several split spectral lines.

Lebedev shows light exerts pressure.

Marconi sends radio signal from England to Newfoundland.

1903Crookes shows that alpha particles cause zinc blende to luminesce.

Wright brothers fly at Kitty Hawk.

1904Fleming invents the rectifier.

Barkla shows x-rays are electromagnetic.

1905Nernst announces that it is impossible to reach absolute zero [third law of thermodynamics].

Einstein publishes three papers - one on Brownian motion confirms existence of atoms, another on photoelectric effect confirms existence of photons, third announces special relativity.

**** finał klasycznej, początek kwantowej elektrodynamiki ****

1906Fessenden demonstrates modulation of radio waves.

De Forest invents the triode.

1907Einstein introduces the principle of equivalence of gravitation and inertia and uses it to predict the gravitational redshift.

Fischer artificially synthesizes peptide amino acid chains and thereby shows that amino acids in proteins are connected by amino group-acid group bonds.

1908Kamerlingh-Onnes liquefies helium.

Haber discovers fixation of nitrogen which allows Germany to make explosives.

Boltwood suggests that minerals can be dated by determining Pb/U ratio.

Rutherford studies scattering of alpha particles by gold.

1909Peary and Henson reach the North Pole.

Rutherford states that alpha particle is helium.

Einstein gets a professorship at University of Zurich.

1911Kamerlingh-Onnes discovers liquid helium is a superconductor.

Millikan measures charge of electron. [demo]

Wilson invents cloud chamber.

Rutherford announces theory of nuclear atom.

Amundsen reaches the South Pole.

Hess studies cosmic rays using balloons.

1912Laue shows x-rays diffracted by crystals.

Bohr begins work on quantum theory of atom.

1913Perrin measures size of atoms via Einstein's explanation of Brownian motion, finally confirms Dalton's atomic theory.

Stark finds strong electric field splits spectral lines.

Geiger invents counter for measuring radiation.

Bohr presents his quantum model of the atom.

1914Rutherford suggests fundamental particle of positive charge is the proton.

Moseley shows x-ray absorption edge of element a function of its atomic number.

Ramanujan publishes Modular Equations and Approximations to pi.

1915Einstein announces theory of general relativity.

Braggs [father and son] use x-rays to determine crystal structures.

1916Lewis introduces theory of chemical bonding.

1917Jeans suggests planets formed when sun encounters another star.

Einstein introduces the idea of stimulated radiation emission.

1919

Ashton uses mass spectrograph to discover isotopes.

Eddington leads a solar eclipse expedition which claims to detect gravitational deflection of light by the Sun.

1920Michelson uses interferometry to measure diameter of Betelgeuse.

1921Capek, a Czech dramatist, introduces the word 'robot' ("forced work") in his play R.U.R.

1922Compton studies X-ray photon scattering by electrons.

1923Michelson uses interferometry to measure speed of light, obtains a value of 299,798,000 m/s.

de Broglie associates wavelength of particles with velocity.

1924Eddington relates mass of star to its luminosity.

Appleton discovers the ionosphere.

Bose and Einstein introduce Bose-Einstein statistics.

1925Millikan names radiation from outer space "cosmic rays".

Pauli announces exclusion principle.

Uhlenbeck and Goudsmit postulate electron spin.

Baird transmits the first television signal.

1926Goddard launches his first rocket.

Schrodinger publishes wave equation for H atom.

Dirac introduces Fermi-Dirac statistics.

Lang's Metropolis features an evil, but sexy, robot.

1927Davisson shows electrons exhibit diffraction.

Bohr states principle of complementarity which says that a phenomenon can be described as wave-like or particle like but not both.

Heisenberg develops uncertainty principle.

Born interprets the probabilistic nature of wavefunctions.

1928

Raman discovers light scattered by molecules with shifted wavelengths.

Fleming discovers penicillin.

Horton and Morrison build the first quartz crystal oscillator clock

1929Hubble shows distance to galaxies related to their velocities.

Bothe develops method of coincidence to study cosmic rays.

Cockcroft and Walton design electrostatic atom smasher.

Gamow proposes hydrogen fusion as the energy source for stars.

1930Oort calculates sun revolves around galactic center once every 200,000,000 years.

Dirac postulates existence of positron.

Chandrasekhar discovers the white dwarf maximum mass limit.

Tombaugh discovers Pluto.

1931Urey discovers heavy hydrogen.

Pauli suggests existence of neutrino.

Van de Graaff develops electrostatic atom smasher.

Godel shows even mathematics is uncertain.

1932Chadwick discovers the neutron.

Anderson discovers the positron.

Heisenberg presents the proton-neutron model of the nucleus and uses it to explain isotopes.

1933Rabi begins work on molecular beams leading to studies of great accuracy.

Zwicky and Baade propose the neutron star idea and suggest that supernovae might be created by the collapse of normal stars to neutron stars---they also point out that such events can explain the cosmic ray background.

1934Joliot - Curies discover artificial radioactivity.

Cherenkov observes radiation in wake of electron's passage.

1935Dempster discovers U-235.

Blackett discovers gamma rays can produce postitron - electron pairs.

Yukawa postulates that nuclear force is an exchange of mesons.

Einstein, Podolsky, and Rosen put forth the EPR paradox.

Richter invents a logarithmic scale to measure the intensity of earthquakes.

1936Wigner works out theory of neutron absorption.

1937Neddermeyer, Anderson, Street, and Stevenson discover muons using cloud chamber measurements of cosmic rays.

1938Hahn and Strassman discover fission of uranium.

Meitner and Frisch determine that nuclear fission is taking place in the Hahn-Strassman-Meitner experiments.

Zworykin develops first practical TV camera.

Bethe works out nuclear mechanism of sun.

1939Einstein writes letter to FDR stating that nuclear weapons could be made.

Elsasser postulates earth's magnetic field due to eddy currents in liquid core.

1940MacMillan discovers neptunium.

1941Seaborg isolates plutonium.

Flerov discovers spontaneous fission of uranium.

1942Enrico Fermi makes the first controlled nuclear chain reaction.

Stuckelberg introduces the propagator to positron theory and interprets positrons as negative energy electrons moving backwards through spacetime.

1943Oppenheimer placed in charge of Manhattan Project.

Schrodinger delivers the 'What Is Life?' lectures at Trinity College, Dublin.

1944Von Braun develops V-2 rocket.

1945World enters nuclear age at Alamogordo on July 16.

Hiroshima destroyed by nuclear weapon on August 6.

1946Bloch and Purcell develop nuclear magnetic resonance.

Eckert and Mauchly announce ENIAC, the first practical entirely electronic computer.

1947Powell discovers pi meson.

Libby introduces carbon-14 dating.

First supersonic flight.

1948Goeppert - Mayer shows nuclei consist of protons and neutrons in shells.

Bardeen, Brattain and Shockley construct the first transistor.

Casimir predicts a rudimentary attractive Casimir force on a parallel plate capacitor.

Bondi, Gold, and Hoyle propose steady state cosmologies based on the perfect cosmological principle.

1949von Neumann computes pi to 2,037 decimal places using ENIAC.

1950Oort suggests sun surrounded by vast cloud of comets.

Turing proposes the `Turing test' criterion for an intelligent machine.

1952World enters thermonuclear age as first fusion weapon explodes

Glaser constructs first bubble chamber.

Franklin uses X-ray diffraction to study the structure of DNA and suggests that its sugar-phosphate backbone is on its outside.

1953Townes produces first maser.

Watson and Crick discover structure of DNA.

Ewing and Heezen discover the Great Global Rift running along the Mid-Oceanic Ridge.

Miller shows that amino acids can be formed when simulated lightning is passed through vessels containing water, methane, ammonia, and hydrogen.

1954Piccard designs bathyscaphe which reaches depth of 2.5 miles.

Construction of the first nuclear power reactor.

First FORTRAN compiler written.1955

Bridgeman creates artificial diamonds from carbon under pressure.

Segre and Chamberlain create anti-protons.

1956Lee and Yang propose parity is violated in beta decay.

Wu discovers parity violation by the weak force in beta decaying cobalt-60.

1957Russians launch Sputnik, first earth satellite.

Townes speculates on building a laser.

Bardeen, Cooper, and Schrieffer develop the BCS theory of superconductivity.

1958Van Allen discovers earth surrounded by belts of radiation.

Mossbauer shows it is possible to produce "recoilless" gamma rays.

1960Gagarin first man to fly in space.

1961Woodward synthesizes chlorophyll.

Gell-Mann and Ne'eman discover the Eightfold Way patterns---SU(3) group.

Shanks and Wrench compute pi to 100,000 decimal places using an inverse-tangent identity and an IBM-7090 computer.

1962Lederman shows that the electron neutrino is distinct from the muon neutrino.

Mariner 2 is the first mission to Venus.

1963Vine and D.H. Matthews explain the stripes of magnetized rocks with alternating magnetic polarities running parallel to mid-ocean ridges as due to sea floor spreading and the periodic geomagnetic field reversals

Gell-Mann and Zweig propose the quark/aces model.

1964

Fitch and Cronin show neutral kaon decay violates CPT invariance.

Bell shows that all local hidden variable theories must satisfy Bell's inequality.

1965Weber puts the first Weber bar gravitational wave detector into operation.

Mariner 4 sends the first clear pictures of Mars.

1966Luna 10 becomes the first spacecraft to orbit the Moon.

1967Gurdon uses nuclear transplantation to clone a clawed frog---first cloning of a vertebrate.

1969

Armstrong first man to walk on moon.

Staelin, Reifenstein, Cocke, Disney, and Taylor discover the Crab Nebula pulsar thus connecting supernovae, neutron stars, and pulsars

Snyder, Buhl, Zuckerman, and Palmer find interstellar formaldehyde

1971Texas Instruments releases the first easily portable electronic calculator.

1972Freedman and J.C. Clauser perform the first polarization correlation test of Bell's inequality.

1973Fairchild Semiconductor releases the first large image forming CCD chip---100 rows and 100 columns.

Ostriker and Peebles discover that the amount of visible matter in the disks of typical spiral galaxies is not enough for Newtonian gravitation to keep the disks from flying apart or drastically changing shape.

1974Richter and Ting discover the J/psi meson implying the existence of the charm quark.

Mariner 10 passes by and photographs Mercury.

1975Perl discovers the tauon.

1976Appel and Haken use a computer to solve the four-color problem.

Viking I and Viking II land on Mars.

1977Apple Computer releases the Apple II.

1978Christy discovers Charon.

1979Voyager 1 and Voyager 2 send back images of Jupiter and its system.

1980Guth proposes the inflationary Big Bang universe as a possible solution to the horizon and flatness problems

Alvarez, Alvarez, Asaro, and Michel propose that a giant comet or asteroid may have struck the Earth approximately 65 million years ago thereby causing massive extinctions and enriching the iridium in the K-T layer.

1983Rubbia, van der Meer, and the CERN UA-1 collaboration find the W and Z intermediate vector bosons

1984

Jeffreys devises a DNA fingerprinting method.

1985Kroto, Heath, O'Brien, Curl, and Smalley discover the unusual stability of the carbon-60 Buckminsterfullerine molecule and deduce its structure.

1986Voyager spacecraft encounters Uranus.

Five spacecraft present at return of Halley's Comet.

Universe discovered to have "bubble-like structure."

Solar neutrino problem plagues physicists.

High temperature superconductors discovered by Bednorz and Muller.

1987

Burstein, Davies, Dressler, Faber, Lynden-Bell, Terlevich, and Wegner claim that a large group of galaxies within about 200 million light years of the Milky Way are moving together towards `The Great Attractor.'

Shelton discovers supernova 1987A in the Large Magellanic Cloud.

Kanada, Bailey, Borwein, and Borwein use iterative modular equation approximations to elliptic integrals and a NEC SX-2 supercomputer to compute pi to 134 million decimal places

1989The Z intermediate vector boson resonance width indicates three quark-lepton generations.

Voyager 2 sends back images of Neptune and its system

1990

Launch of the Hubble Space Telescope.

1992COBE satellite detects unevenness in cosmic background radiation arising from 'lumpy' structure at Big Bang.

Solar neutrinos detected by gallium detectors; 1.6 atoms per day react in 1029 atom detector; new results still lower than value predicted by standard solar model.

1994Xia proves that a system of three bodies moving under the influence of gravity is not integrable and is chaotic.

1997Sojourner, a six-wheeled robot rover the size of a microwave oven, roams the surface of Mars.

Wilmut announces he has cloned a sheep.

1998

Rather than slowing down, the Universe is found to be expanding at an ever increasing rate. This finding ties together numerous elements into a consistent cosmic portrait.

A torrent of gamma rays from a magnetar, a highly magnetized star, located 20,000 lightyears from Earth disrupts communication satellites.

The shortfall of neutrinos passing through the Earth presents strongest evidence yet of neutrino mass.

Quantum teleportation is demonstrated when a photon's polarization state is instantly transferred to a remote photon.

The search for magnetic monopoles with high particle masses comes up empty.