A CHRONOLOGY OF THE ATOMIC VIEW OF NATURE

 
c. 550 B.C. THALES of Miletus (Greece, c. 640-546 B.C.) recorded the attractive properties of rubbed amber and of lodestone.
 
c. 450 B.C. LEUCIPPUS (Greece) proposed an atomic concept of matter. 
 
c. 400 B.C. DEMOCRITUS of Abdera (Greece, c. 460-357 B.C.) pupil of Leucippus,  was the most famous of the atomists in ancient times. He taught: "The only existing things are the atoms and empty space; all else is mere opinion."
 
c. 335 B.C. ARISTOTLE (Greece, 384-322 B.C.) held that all matter was basically composed of the  same continuous primordial stuff.
 
c. 300  B.C. EPICURUS of Samos (Greece, c. 342-270 B.C.) founded a philosophical  system based on the atomism of Democritus.
 
c. 300 B.C. ZENO of Cition (Greece, c. 336-264 B.C.) founded the Stoic school of philosophy which held that matter, space, etc. were continuous.
 
c. 60 B.C. TITUS LUCRETIUS CARUS (Rome, c. 96-55 B.C.) attempted to formulate a rational explanation of natural phenomena by extending the beliefs of Democritus and Epicurus. 
His poem,  De Rerum Natura, is the most complete record of Greek atomism extant. The atomism of antiquity was primarily a system of metaphysics. The atomic view of matter in the modern sense was barely introduced in its most elementary form by the beginning of the 19th century.
 
c. 400 SAINT AUGUSTINE (Aurelius Augustinus) (North Africa, 354-430) was the first to report that  the forces exerted by rubbed amber and by lodestone are different properties.
 
c. 1600 WILLIAM GILBERT (England, 1540-1603) made the first detailed study of magnetism and also showed that, in addition to amber, many other materials can be electrified.
 
1638 GALILEO GALILEI (Italy, 1564-1642) published Discors e Dimostrazioni Matematiche intorno a due nuove Scienze attenti alla Mecanica e Movementi locali (Discourses and Methematical Demonstrations concerning Two New Sciences pertaining to Mechanics and Local Motions, usually contracted to two New Sciences).  This account of Galileo's contrubutions to science establishes him as the founder of dynamics.   He was the first to make extensive use of the experimental method to study natural phenomena.  From his time on, induction from experiment replaced the teleology of the scholastics as a guiding principle in the organization of the natural sciences.
 
1650-1700 ROBERT BOYLE (England, 1627-1691) and gave qualitative explanations of Boyle's law by assuming a kinetic theory of gases.
ROBERT HOOKE (England, 1635 1703) and
ISAAC NEWTON (England, 1642-1727)
 
1675 JEAN PICARD (France, 1620-1682) observed the luminous glow in the Torricellian vacuum of a barometer produced by motion of the mercury when the instrument was carried from place to place. 
 
1675 ISAAC NEWTON (England, 1642-1727) developed a corpuscular theory of light.
 
1676 OLE CHRISTENSEN ROEMER (Denmark, 1644-1710) was the first to show that the velocity of light is finite. His conclusion was based on the variations of the time intervals between consecutive eclipses of one of the moons of Jupiter during the course of the revolution of the earth around the sun.
 
1678 CHRISTIAN HUYGENS (CHRISTIAAN HUYGHENS) (Netherlands, 1629-1695) developed a wave theory of light in which light was regarded as composed of longitudinal  "pulses" consisting of compressions and rarefactions, similar to sound, in an extremely  thin, all-pervading medium which he called the aether. The concept that light is a periodic 
wave motion was introduced in about 1750 by Leonard (Leonhard) Euler (Switzerland,  Germany,  Russia, 1707-1783).   Not only did Huygens correctly account for the refraction of light by transparent bodies by means of spherical emanations (wavelets), but also, by using both spherical and spheroidal wavelets, he became the first one to explain double refraction, a phenomenon that was discovered in 1669 by Erasmus Bartholinus (Denmark, 1625-1692).
 
1687 ISAAC NEWTON (England, 1642-1727) published Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) which contains the fundamental laws of classical dynamics and the law of gravitation. The synthesis involved in obtaining these laws is one of the greatest achievements of the human mind.
 
1705 FRANCIS HAUKSBEE (England, d. 1713 made a "powerful" electrostatic generator and discovered the conditions for producing luminous electric discharges in gases.
 
1728 JAMES BRADLEY (England, 1693-1762) explained the aberration of light from stars by taking the vector sum of the orbital velicity of the earth v and the free-space velocity of light c, and showed that the angle of aberration was a function of the ratio of these velocites, v/c. On this basis, he also showed that the revolution of the earth around the sun correctly accounted for the observed cyclic change in the aberration of star light. (The Anti-copernicans, still numerous in the first half of the 18th century, were unable to refute this explanation of the change.) Bradley's work is the first of many instances that seemed to show that the value of the velocity of light depends on the motion of the observer.
 
1731 STEPHEN GRAY (England, 1666/7-1736) discovered the conduction of electricity.
 
1734 CHARLES FRANCOIS de CISTERNAY DUFAY (France, 1698-1739) showed that there are two kinds of electrification, resinous and vitreous, and then proposed a two-fluid theory of electric discharge. He also found that the air in the vicinity of a hot body is conducting.
 
1738 DANIEL BERNOULLI (Switzerland, 1700-1782) was the first to devise a quantitative kinetic theory of gases.
 
1745 EWALD JURGEN von KLEIST (Germany, d. 1748) and independently made the first capacitors, called Leyden jars.
PEITER VAN MUSSCHENBROEK (Netherlands, 1692-1761)
 
1752 BENJAMIN FRANKLIN (USA, 1707-1790) experimentally verified the electrical nature of lightning and introduced the one-fluid theory of flow of electricity - from surplus of positive to deficiency or negative. His theory contained the first clear statement of the law of conservation of electric charge.
 
1753 JOHN CANTON (England, 1718-1772) discovered the facts of electrostatic induction.
 
1766 HENRY CAVENDISH (England, 1731-1810) discovered hydrogen. Within the next score of years he found the inverse square law of force action between electric charges and other 
important laws of electricity but, because of excessive shyness, he withheld announcement of his experiments. The great extent of his work was not known until James Clerk Maxwell published Cavendish's papers in 1879.
 
1785 CHARLES AUGUSTIN COULOMB (France, 1736-1806) determined the law of force action between electric charges.
 
1789 ANTOINE LAURENT LAVOISIER (France, 1734-1794) published a book containing a well-founded concept of chemical elements and the verification of the law of conservation of matter in chemical reactions.
 
1791 BRYAN HIGGINS (Ireland, 1737-1820) and reported the first of a series of experiments leading to the laws of chemical combination.
WILLIAM HIGGINS (Ireland, c. 1769-1825)
 
1799 JOSEPH LOUIS PROUST (France, Spain, 1754-1826) established the law of definite proportions for chemical compounds.
 
1800 ALESSANDRO GUISEPPE ANTONIO ANASTASIO VOLTA (Italy, 1745-1827) made the first voltaic pile (battery), based on his discovery of the fundamental conditions necessary to  produce the "animal electricity" that had first been observed in 1780 by Aloisio (or Luigi) Galvani (Italy, 1737-1798).
 
1801 THOMAS YOUNG (England, 1773-1829) showed that his interference experiments verified the  wave theory of light.
 
1803 JOHN DALTON (England, 1766-1844) published the first of a series of papers introducing atomic weights, establishing the law of multiple proportions, and founding the atomic theory of matter.
 
1808  JOSEPH LOUIS GAY-LuSSAC (France, 1778-1850) discovered the law of combining volumes of gases.
 
1810-1875 ETIENNE LOUIS MALUS (France, 1775-1812) established conclusively, through many experiments, especially in physical optics, that light is a transverse wave. Several of these men made precise measurements of the velocity of light in various media. In 1818 Arago found that the refraction of a prism for star light was the same for light incident in the direction of the earth's orbital velocity v as for that coming in the opposite direction. This unexpected null result was explained that same year by Fresnel's ether-dray theory, which assumed partial ether entrainment in transparent media by an amount depending upon the first power of v. This theory appeard fully verified by the measurements of the speed of light in moving water by Fizeau in 1851 and, in 1871, by the observations of the aberation of star light with a water filled telescope by GEORGE BIDDELL AIRY (England, 1801-1892).
DOMINIQUE FRANCOIS JEAN ARAGO (France, 1786-1853)
AUGUSTIN JEAN FRESNEL (France, 1788-1827)
JEAN BERNARD LEON FOUCAULT (France, 1819-1868)
HIPPOLYTE LOUIS FIZEAU (France, 1819-1896)
MARIE ALFRED CORNU (France, 1841-1902)
 
1811 LORENZO ROMANO AMADEO AVOGADRO (Italy, 1776-1856) introduced Avogadro's hypothesis and differentiated between atoms and molecules.
 
1813 JONS JACOB BERZELIUS (Sweden, 1779-1848) introduced the present symbols for the chemical elements.
 
1815 WILLIAM PROUT (England, 1875-1850) proposed that all elements are composed of an integral number of hydrogen atoms.
 
1815-1820 JOSEPH FRAUNHOFER (Germany, 1787-1826) noted the spectral lines of several elements, obtained the first grating spectra, and observed the Fraunhofer (absorption) lines in solar spectra. 
 
1819 PIERRE LOUIS DULONG (France, 1785-1838) and found the law of constancy of molar specific heat capacities of elements.
ALEXIS THERESE PETIT (France, 1791-1821)
 
1820 HANS CHRISTIAN OERSTED (Denmark, 1777-1851) discovered that an electric current produces a magnetic field. This initiated the study of electromagnetism.
 
1821 THOMAS JOHANN SEEBECK (Russia, Germany, 1770-1831) discovered thermoelectricity.
 
1823 ANDRE MARIE AMPERE (France, 1775-1836) published his mathematical theory of electromagnetism and the laws of magnetic field produced by currents. Some of these laws were also discovered independently by Jean Baptiste Biot (France, 1774-1862) and Felix Savart (France, 1791-1841).
 
1826 GEORG SIMON OHM (Germany, 1787-1854) discovered Ohm's law.
 
1827 ROBERT BROWN (England, 1773-1858) discovered Brownian movement.
 
1831 MICHAEL FARADAY (England, 1791-1867) and independently discovered electromagnetic induction.
JOSEPH HENRY (USA, 1797-1878)
 
1833 MICHAEL FARADAY (England, 1791-1867) discovered the laws of electrolysis and introduced the terms "anode" and "cathode."
 
1835 JOSEPH HENRY (USA, 1797-1878) discovered self-induction and, in 1842, oscillatory electric discharge.
 
1842 JOHANN CHRISTIAN DOPPLER (Austria, 1803-1853) deduced a relation that showed that the observed frequency of waves depends upon the relative motion of the source and the observer.
 
1842 JULIUS ROBERT MAYER (Germany, 1814-1878) calculated the mechanical equivalent of heat theoretically from the specific heats of gases and vaguely proposed a law of conservation of energy based on "Ex nihilo, nihil fit." His work was not published for several years.
 
1843 JAMES PRESCOTT JOULE (England, 1814-1889) published the first of a series of reliable experimental results that showed the constancy of the relation between mechanical energy and heat-a basic step toward the law of conservation of energy.
 
1847 HERMANN LUDWIG FERDINAND VON HELMOLTZ (Germany, 1821-1894) proposed the law of conservation of "force" (energy).
 
1848 WILLIAM THOMSON (Lord Kelvin, 1st Baron) (Ireland, Scotland, 1824-1907) introduced absolute temperature.
 
1850 RUDOLPH JULIUS EMANUEL CLAUSIUS (Germany, 1822-1888) announced the second law of thermodynamics.  Lord Kelvin independently found the same law in 1852.
 
1850-1900 AUGUST KARL KROENIG (Germany, 1822-1879) developed the kinetic theory of gases and founded statistical mechanics. Maxwell derived his speed distribution law in 1860, Clausius introduced the concept of entropy in 1865, and Boltzmann related entropy to thermodynamic probability in 1877.
RUDOLPH JULIUS  EMANUEL CLAUSIUS (Germany, 1822-1888)
JAMES CLERK MAXWELL (Scotland, England, 1831-1879)
LUDWIG BOLTZMANN (Austria, 1844-1906), and
JOSIAH WILLARD GIBBS (USA, 1839-1903)
 
1858 STANISLAO CANNIZZARO (Italy, 1826-1910) resolved the conflicting values of atomic weights by clarifying the terms "atomic," "molecular," and "equivalent" weights.
 
1859 GUSTAV ROBERT KIRCHHOFF (Germany, 1824-1887) showed that the ratio of the emittance to the absorptance for a given wavelength of radiation is the same for all surfaces at the same temperature, and introduced the concept of cavity (Hohlraum) or blackbody radiation.
 
1859 HEINRICH GEISSLER (Germany, 1814-1879) and discovered the "rays" (now called cathode rays) from the negative electrode in gaseous discharge tubes.
JULIUS PLUECKER (Germany, 1801-1868)
 
1863 JAMES ALEXANDER REINA NEWLANDS (England, 1837-1898) Stated the law of octaves, a limited and elementary form of the periodic table of the elements.
 
1864 JAMES CLERK MAXWELL   (Scotland, England, 1831-1879) wrote A Dynamical Theory of the Electromagnetic Field, a paper synthesizing electricity, magnetism, and light.  This  was probably the greatest work since Newton's Principia.
 
1865 JOSEPH LOSCHMIDT (Germany, 1821-1895) used the equations of the kinetic theory of gases to make the first determination of Avogadro's number and of molecular diameters.
 
1869 DMITRI IVANOVICH MENDELEEV (Russia, 1834-1907) and independently introduced the periodic table of the elements, a concise summary of years of experimental and theoretical chemistry. The table is both mnemonic and heuristic.
JULIUS LOTHAR MEYER (Germany, 1830-1895)
 
1869 JOHANN WILHELM HITTORF (Germany, 1824-1914) observed the deflection of rays from the cathode in a discharge tube, by means of a magnetic field.
 
1871 CROMWELL FLEETWOOD VARLEY (England, 1828-1883) found that the rays from the cathode are negatively charged.
 
1876 EUGEN GOLDSTEIN (Germany, 1850-1930) introduced the name "cathode rays" and began experiments leading eventually to the discovery of the positive counterpart, Kanalstrahlen (channel or canal rays). In 1886 he suggested that the aurora is due to cathode rays from the sun.
 
1877 WILLIAM RAMSAY (England, 1852-1916) and, independently,

JOSEPH DELSAULX (France, 1828-1891) and

IGNACE J. J. CARBONELLE (France, 1829-1889)

advanced the first rather complete qualitative explaination of Brownian movement by attributing it to molecular impacat. Some years later Ramsay discovered several of the noble gases, and made important contributions to the study of radioactivity. He was awarded the Nobel prize for chemistry in 1904.
 
1879 EDWIN HERBERT HALL (USA, 1855-1938) discovered the existence of a potential difference between the opposite edges of a metal strip carrying a longitudinal electric current, when the plane of the strip is set normal to a magnetic field. This is called the Hall effect.
 
1879 WILLIAM CROOKES (England, 1832-1919) began a long series of brilliant experiments on the discharge of electricity through gases.
 
1879 JOSEF STEFAN (Austria, 1835-1893) announced Stefan's law, which gives the total energy radiated by a blackbody. This was the first successful attempt to connect absolute temperature and radiation.
 
1881 JULIUS ELSTER (Germany, 1854-1920), and started a long, systematic investigation of electrical effects produced by incandescent solids.
HANS FRIEDRICH GEITEL (Germany, 1855-1923)
 
1883 THOMAS ALVA EDISON (USA, 1847-1931) discovered the Edison effect, the emission of negative electricity from incandescent filaments in a vacuum.
 
1884 JOHANN JAKOB BALMER (Switzerland, 1825-1898) found an empirical wavelenth relation for a spectral series of hydrogen. This was the first series equation found for any spectrum.
 
1887 SVANTE AUGUST ARRHENIUS (Sweden, 1859-1927) conclusively estabished the ion dissociation theory of electrolytes which grew from suggestions made by Clausius in 1857. Arrhenius was awarded the Nobel prize for chemisty in 1903.
 
1887 ALBERT ABRAHAM MICHELSON (Germany, USA, 1852-1931) and

EDWARD WILLIAMS MORLEY (USA, 1838-1923)

performed the first precision experiment that showed the earth has no ether drift. In a letter to Nature in 1879 Maxwell pointed out that evidence of ether drift had to be sought in second-order effects-those depending on v2/c2. These are involved in interference methods. The first trial by Michelson in 1881 gave inconclusive results. Michelson was aarded the Nobel prize for physics in 1907.
 
1887 HEINRICH RUDOLPH HERTZ (Germany, 1857-1894) discovered the photoelectric effect while verifying the existence of the electromagnetic waves predicted by Maxwell.
 
1888 WILHELM HALLWACHS (Germany, 1859-1922) showed that only negative charges are emitted in the photoelectric effect.
 
1890 JOHANNES ROBERT RYDBERG (Sweden, 1854-1919) found an empirical wavelength relation for complex series of spectral lines.
 
1891 JOHNSTONE STONEY (England, 1826-1911) introduced the name "electron" for an elementary unit of negative charge in electrolysis.
 
1892 GEORGE FRANCIS FITZGERALD (Ireland, 1851-1901) and  independently made the ad hoc assumption of contraction of length to account for the null result of the Michelson-Morley experiment. As Lorentz successively refined his electric theory of matter to conform with the results of new experiments, he obtained the space and time transformations later derived by Einstein. For later work Lorentz was awarded the Nobel prize for physics jointly with P. Zeeman in 1902.
HENDRIK ANTOON LORENTZ (Netherlands, 1853-1929)
 
1893 WILHELM WIEN (Germany, 1864-1928) derived his blackbody radiation displacement law.  His blackbody radiation law was announced in 1896. He was awarded the Nobel prize for physics in 1911.
 
1893 PHILIPP EDUARD ANTON VON LENARD (Hungary, Germany, 1862-1947)  investigated cathode rays by passing them through a Lenard window (thin-window) tube into air.  For this and later work he was awarded the Nobel prize for physics in 1905.
 
1895 JEAN BAPTISTE PERRIN (France, 1870-1942) demonstrated conclusively that cathode rays are negatively charged. For this and later work he was awarded the Nobel prize for physics in 1926.
 
1895 WILHELM CONRAD ROENTGEN (Germany, 1845-1923) discovered x-rays.  He was awarded the Nobel prize for physics in 1901.
 
1896 ANTOINE HENRI BECQUEREL (France, 1852-1908) discovered the radioactivity of uranium.  He was awarded the Nobel prize for physics jointly with the Curies in 1903.
 
1896 PIETER ZEEMAN (Netherlands, 1865-1943) observed the splitting of spectral lines radiated by excited atoms in an intense magnetic field. The early theory of this effect was derived by H. A. LORENTZ (Netherlands). They were jointly awarded the Nobel prize for physics in 1902.
 
1896 OLIVER LODGE (England, 1851-1940) reported that, contrary to expectations, there was no detectable ether drag on light passing between two large closely spaced disks of steel rotating at enormous speeds even when the disks were strongly magnetized or electrified.
 
1897 JOSEPH JOHN THOMSON (England, 1856-1940) determined q/m for cathode rays.  He was awarded the Nobel prize for physics in 1906.
 
1897 ERNEST RUTHERFORD (Lord Rutherford of Nelson, 1st Baron) 
(New Zealand, Canada,  England, 1871-1937)
showed that the radiation from uranium was complex, consisting of "soft" (alpha) and "hard" (beta) rays. He was awarded the Nobel prize for chemistry in 1908.
 
1898 PIERRE CURIE (France, 1859-1906) and isolated radium and polonium.  They were awarded the Nobel prize for physics jointly with H. Becquerel in 1903.  Marie Curie was also awarded the Nobel prize for chemistry in 1911.
MARIE SKLODOWSKA CURIE (Poland, France, 1867-1934)
 
1899 ANTOINE HENRI BECQUEREL (France, 1852-1908), and independently observed the magnetic deflection of alpha and beta rays.
STEFAN MEYER (Austria, 1872-1949), and
EGON VON SCHWEIDLER (Austria, 1873-1948), and 
FREDERICK OTTO GIESEL (Germany, 1852-1927)
 
1899 JULIUS ELSTER (Germany, 1854-1920), and determined the law of radioactive decay experimentally.
HANS GEITEL (1855-1923)
 
1899 PHILIPP EDUARD ANTON VON LENARD (Germany, 1862-1947) showed that photoelectric emission is due to electrons.
 
1899 JOSEPH JOHN THOMSON (England, 1856-1940) showed that the Edison effect is due to electrons.
 
1899 OTTO LUMMER (Russia, Germany, 1860-1925), and made precise measurements of the 
intensity-wavelength distribution of blackbody radiation.
ERNST GEORG PRINGSHEIM (Germany, 1881-1917), and
FERDINAND KURLBAUM (Germany, 1857-1927), and 
HEINRICH RUBENS (Germany, 1865-1922)
 
1900 JOHN WILLIAM STRUTT (Lord Rayleigh, 3rd Baron), (England, 1842-1919), and announced a blackbody radiation law. 
 
JAMES HOPWOOD JEANS (England, 1877-1946) The derivation of the blackbody radiation law was re-examined in collaboration with James H. Jeans, and, after publication in 1905, became known as the Rayleigh-Jeans law.  Rayleigh was awarded the Nobel prize for physics in 1904.
 
1900 MAX KARL ERNST LUDWIG PLANCK (Germany, 1858-1947) introduced the quantum theory of radiation-a revolutionary concept. He was awarded the Nobel prize for physics in 1918.
 
1900 ANTOINE HENRI BECQUEREL (France, 1852-1908) showed that beta rays are identical with cathode-ray  corpuscles.
 
1900 PAUL VILLARD (France, 1860-1934) discovered gamma rays.
 
1902 PHILIPP EDUARD ANTON VON LENARD (Germany, 1862-1947) discovered photoelectric threshold frequency and also that the kinetic energy of photoelectrons is independent of the intensity of the incident light.
 
1903 FREDERIC THOMAS TROUTON (Ireland, England, 1863-1922), and were unable to observe any orienting torque on a suspended, charged capacitor as predicted on the basis of an ether drift (a second-order effect).
H. R. NOBLE (England)
   
1903 ERNEST RUTHERFORD (Lord Rutherford of Nelson, 1st Baron) 
(New Zealand, Canada,  England, 1871-1937), and
showed that every radioactive process is a transmutation of elements. Soddy was awarded the Nobel prize for chemistry in 1921.
FREDERIC SODDY (England, 1877-1956)
 
1903 WILLIAM CROOKES (England, 1832-1919), and, independently, found that the luminescence produced when alpha particles strike zinc sulfide consists of discrete flashes of light of scintillations. This led to a method of counting individual alpha particles.
JULIUS ELSTER (Germany, 1854-1920), and
HANS FRIEDRICH GEITEL (Germany, 1855-1923)
 
1904 WILLIAM RAMSAY (England, 1852-1916), and discovered the remarkable occurrence of helium in all radium compounds.
FREDERIC SODDY (England, 1877-1956)
 
1904 DEWITT BRISTOL BRACE (USA, 1859-1905) found no trace of the double refraction predicted for an isotropic transparent body when it is rotated from parallel to the ether drift to noral to it (a second-order effect). This type of experiment had been suggested by the elder Lord Rayleigh.
 
1904 JOHN AMBROSE FLEMING (England, 1849-1945) applied the Edison effect to make the first thermionic valve ("radio" tube).
 
1904 MARYAN VON SMOLUCHOWSKI (Austria, 1872-1919) proposed a statistical theory of Brownian movement.
 
1905 ALBERT EINSTEIN (Germany, Switzerland, USA, 1879-1955) completed the statistical theory of Brownian movement, introduced the quantum explanation of the photoelectric effect, and announced the special theory of relativity.  He was awarded the Nobel prize for physics in 1921.  The citation stated that the award was "for his contributions to mathematical physics, and especially for his discovery of the law of the photoelectric effect."
 
1905 EGON VON SCHWEIDLER (Austria, 1873-1948) derived the law of radioactive decay from probability theory, not obtainable from causality.
 
1906 OWEN WILLANS RICHARDSON (England, 1879-1959) began a long series of important investigations on the emission of electricity from hot bodies (thermionic emission). He was awarded the Nobel prize for physics in 1928.
 
1906 LEE DE FOREST (USA, 1873-1961) made the first audion (triode) by introducing a grid into a Fleming valve.
 
1907-1912 JOSEPH JOHN THOMSON (England, 1856-1940) devised methods of positive-ray analysis. This  was the beginning of mass spectroscopy.
 
1908 WALTER RITZ (Switzerland, 1878-1909) announced the combination principle for computing the frequencies of spectral lines.
 
1908 LOUIS CARL HEINRICH FRIEDRICH PASCHEN (Germany, 1865-1947) experimentally verified the existence of a spectral series of hydrogen in the near infrared predicted by the Rydberg-Ritz relation.
 
1908 CHARLES GLOVER BARKLA (England, 1877-1944) discovered from absorption experiments that the secondary x-rays of various elements are composed of groups of characteristic x-rays which he called the K, L, and 117 radiations, and demonstrated the polarization of x-rays. He was awarded the Nobel prize for physics in 1917.
 
1908 JEAN BAPTISTE PERRIN (France, 1870-1942) verified experimentally the several equations for Brownian movement, obtained good values of Avogadro's number, and showed that equipartition of energy held for small particles suspended in a stationary liquid.
 
1908 HERMANN MINKOWSKI (Lithuania, Germany, 1864-1909) developed a geometrical interpretation of the special theory of relativity in which time and the three space coordinates all had the same validity in a four dimensional continuum.
 
1908-1910 ALFRED HEINRICH BUCHERER (Germany, 1863-1927), independently made precision measurements of the mass of an electron as a function of its velocity.  The results verified the Lorentz-Einstein mass variation relation.
E. HUPKA (Germany), and
CHARLES EUGENE GUYE (France, 1866-1942) and
SIMON RATNOWSKY (Russia, Switzerland, 1884-1945)
 
1909 GUGLIELMO MARCONI (Italy, 1874-1937) and were jointly awarded the Nobel prize for physics - the former for combining the basic knowledge about Hertzian waves to produce wireless telegraphy, and the latter for the study, production, and use of electrical oscillators. Braun also developed the Braun tube, called the "cathode-ray" tube in the USA.
CARL FERDINAND BRAUN (Germany, 1850-1918)
 
1909 ERNEST RUTHERFORD (Lord Rutherford of Nelson, 1st Baron) 
(New Zealand, Canada,  England, 1871-1937), and
showed that alpha particles are doubly ionized helium atoms.
THOMAS ROYDS (England, 1884-1955)
 
1909-1910 T. WULF (France) observed the rate of leak of charge from a highly insulated electroscope placed at the top of the Eiffel Tower, and
ALBERT GOCKEL (Switzerland, 1860-1927) studied the same effects in balloon ascents up to 4500 meters. Both found the leakage rate greater than at the surface of the earth. Their results were unexpected because the effect at ground level had been acribed to local radioactivity of the soil.
 
1909-1911 ROBERT ANDREWS MILLIKAN (USA, 1868-1953) established the law of multiple proportions for electric charges and made the first precise determination of the electronic charge. He was awarded the Nobel prize for physics in 1923.
 
1910-1912 VICTOR FRANZ HESS (Austria, USA, 1883-1964) and discovered cosmic rays.  Hess was awarded the Nobel prize for physics jointly with C. D. Anderson in 1936.
WERNER KOL HOERSTER (Austria, 1887-1945)
 
1911 PETER JOSEPH WILHELM DEBYE (Netherlands, Switzerland, Germany, USA, 1884-1966) used the quantum theory to obtain a rather complete theory of specific heats, and later applied the quantum concept to many problems in physical chemistry. He was awarded the Nobel prize for chemistry in 1936.
 
1911-1913 ERNEST RUTHERFORD (Lord Rutherford of Nelson, 1st Baron) 
(New Zealand, Canada,  England, 1871-1937), and
showed that a nuclear model of the atom was required to explain their experiments on alpha-particle scattering by thin metal foils.
HANS GEIGER (Germany, 1882-1945), and 
ERNEST  MARSDEN (England, 1889-1970)
 
1911 CHARLES THOMSON BEES WILSON (Scotland, England, 1869-1959) made the first expansion cloud chamber.  This is the most important device in nuclear physics.  He was awarded the Nobel prize for physics jointly with A. H. Compton in 1927.
 
1912  MAX FELIX THEODOR von LADE (Germany, 1879-1960) with established the wave nature of x-rays by crystal diffraction. Laue was awarded the Nobel prize for physics in 1914.
WALTER FRIEDRICH (Germany, 1883-1969) and
PAUL C. M. KNIPPING (Germany, 1883-1935)
   
1912 HANS GEIGER (Germany, 1882-1945), and obtained an empirical law relating the energy of an emitted alpha particle to the disintegration constant of the parent nucleus.
JOHN MITCHELL NUTTALL (England, 1890-1958)
 
1913 HANS GEIGER (Germany, 1882-1945) published a detailed description of the point discharge counter tube which was developed from a simpler form first made in 1908.  This instrument was greatly improved in 1928.
 
1913 FREDERIC SODDY (England, 1877-1956), and announced the laws of displacement in the periodic table for elements undergoing radioactive decay.  Soddy introduced the term "isotopes."
KASIMIR FAJANS (Poland, Germany, 1887-1975)
 
1913 GEORGE CHARLES DE HEVESY (Hungary, Germany, Sweden, 1885-1966) and used radium-D, an isotope of lead, to study the solubility and the chemistry of lead compounds. This was the first use of an isotope as a tracer element. Hevesy was awarded the Nobel prize for chemistry in 1943.
FRITZ ADOLF PANETH (Austria, 1887-1959)
 
1913 NIELS HENRIK DAVID BOHR (Denmark, 1885-1962) developed the first successful theory of atomic structure.  He was awarded the Nobel prize for physics in 1922.
 
1913 JOHANNES STARK (Germany, 1874-1957) observed the splitting of spectral lines radiated by excited atoms in an intense electric field.  He was awarded the Nobel prize for physics in 1919.
 
1913 JAMES FRANCK (Germany, USA, 1882-1964) and supported the Bohr atomic theory with their measurements of ionization and resonance potentials. They were awarded the Nobel prize for physics in 1925.
GUSTAV HERTZ (Germany, 1887-1975)
   
1913 WILLIAM HENRY BRAGG (England, 1862-1942) and son, studied x-ray "reflection" from crystals and devised an x-ray spectrometer.  They were awarded the Nobel prize for physics in 1915.
WILLIAM LAWRENCE BRAGG (Australia, England, 1890-1971)
 
1914 HENRY GWYN JEFFREY MOSELEY (England, 1884-1915) made x-ray spectrograms of the elements and established the identity of the ordinal number of an element in the periodic table with its nuclear charge (atomic number).
 
1914 KARL MANNE GEORG SIEGBAHN (Sweden, 1886-1978) began a long series of pioneer researches in the theory and application of precision x-ray spectroscopy. He was awarded the Nobel prize for physics in 1924.
 
1915 ARNOLD JOHANNES WILHELM SOMMERFELD (Germany, 1868-1951) improved the Bohr atomic model by introducing elliptical orbits and relativistic effects.
 
1915 WILLIAM DUANE (USA, 1872-1935) and showed that the short-wavelength limit of emitted xradiation is determined by the quantum theory.
FRANKLIN LIVINGSTON HUNT (USA, b. 1883)
 
1915 ALBERT EINSTEIN (Germany, Switzerland, USA, 1879-1955) announced the general theory of relativity. It considers the observations of phenomena on accelerated reference frames.
 
1916 ROBERT ANDREWS MILLIKAN (USA, 1868-1953) experimentally verified Einstein's photoelectric equation.
 
1916 PETER JOSEPH WILHELM DEBYE (Netherlands, Switzerland, Germany, USA, 1884-1966) obtained the first x-ray powder diffraction patterns.
PAUL SCHERRER (Switzerland, b. 1890), and, independently,
ALBERT WALLACE HULL (USA, 1880-1966)
 
1916 THEODORE LYMAN (USA, 1874-1954) found the Lyman series lines predicted by   Bohr's theory of the hydrogen atom. Lyman had observed at least one of these lines as early as 1906.
 
1919 ERNEST RUTHERFORD (Lord Rutherford of Nelson, 1st Baron) 
(New Zealand, Canada,  England, 1871-1937)
produced hydrogen and oxygen by alpha-particle bombardment of nitrogen, the first "man-made" transmutation of an element.
 
1919 FRANCIS WILLIAM ASTON (England, 1877-1945) made the first high precision determinations of isotopic masses. He was awarded the Nobel prize for chemistry in 1922.
 
1919 The observations made during a total solar eclipse in this year by an expedition from the Royal Astronomical Society and the Royal Society of London confirmed the deviation of starlight in the gravitational field of the sun as predicted by the general theory of relativity.  The strongest support for this theory came later from the agreement between the calculated and observed values of the precession of the perihelion of Mercury.
 
1921 OTTO STERN (Germany, USA, 1888-1969) and verified the space quantization of silver atoms in a magnetic field and measured their magnetic moment. Stern was awarded the Nobel prize for physics in 1943.
WALTER GERLACH (Germany, 1889-1979)
 
1923 ARTHUR HOLLY COMPTON (USA, 1892-1962) discovered the Compton effect, which showed that a photon has momentum. He was awarded the Nobel prize for physics jointly with C. T. R. Wilson in 1927.
 
1924 EDWARD VICTOR APPLETON (England, 1892-1965) began a series of experiments that    established the existence and properties of ionized layers in the high atmosphere.  Such layers had been postulated in 1902 by
ARTHUR EDWIN KENNELLY (India, USA, 1861-1939) and, independently, by
OLIVER HEAVISIDE (England, 1850-1925) to account for-long-distance wireless telegraphy.  Appleton was awarded the Nobel prize for physics in 1947.
 
1924 SATYENDRANATH BOSE (India, 1894-1974) and independently developed the statistics "obeyed" by bosons, a collective name for photons, nuclei of even mass number, and certain other particles.
ALBERT EINSTEIN (Germany, Switzerland, USA, 1879-1955)
 
1924 LOUIS VICTOR, DUC DE BROGLIE (France, 1892-1987) introduced the concept of de Broglie waves, the beginning of the wave theory of matter.  He was awarded the Nobel prize for physics in 1929.
 
1925 WALTER M. ELSASSER (Germany, USA, 1904-1991) predicted from de Broglie theory that electrons could be diffracted by crystals.
 
1925 CHARLES DRUMMOND ELLIS (England, 1895-1980) and established that in a number of elements the emission of either an alpha or a beta particle precedes the radiation of gamma rays, and thus the latter should be associated with the daughter product, not with the parent.
W. A. WOOSTER (England)
 
1925 PIERRE VICTOR AUGER (France, 1899-1993) discovered a type of energy transition in   which an atom goes from a higher to a lower state by ejecting one of its own electrons, without the emission of electromagnetic radiation.
 
1925 GEORGE EUGENE UHLENBECK (Java, Netherlands, USA, 1900-1988) and  introduced spin and magnetic moment of the electron into atomic theory.
SAMUEL ABRAHAM GOUDSMIT (Netherlands, USA, 1902-1978)
 
1925 WOLFGANG PAULI (Austria, Switzerland, 1900-1958) announced the exclusion principle.  He was awarded the Nobel prize for physics in 1945.
 
1925 PATRICK MAYNARD STUART BLACKETT (England, 1897-1974) obtained the first cloud-chamber tracks of the induced transmutation of nitrogen and of other elements, and later made many cosmic-ray studies. He was awarded the Nobel prize for physics in 1948.
 
1925  MAX BORN (Germany, 1882-1970), developed quantum mechanics. Later, Born originated the statistical interpretation of wave mechanics, and he was awarded the Nobel prize for physics jointly with W. Bothe in 1954.
WERNER KARL HEISENBERG (Germany, 1901-1976), and
PASCUAL JORDAN (Germany, 1902-1980)
 
1926 ERWIN SCHROEDINGER (Austria, Ireland, 1887-1961) proposed the wavemechanical theory of the hydrogen atom. He was awarded the Nobel prize for physics jointly with Paul Adrien Maurice Dirac in 1933.
 
1926 ENRICO FERMI (Italy, USA, 1901-1954) and  independently developed the statistics "obeyed" by fermions, a collective name for nuclei of odd mass number, some particles, and electrons, particularly the electron gas in a condictor. Each was awarded the Nobel prize for work listed later in this chronology.
PAUL ADRIEN MAURICE DIRAC (England, 1902-1984)
 
1926 EUGENE PAUL WIGNER (Hungary, USA, 1902-1995) published the first of a long series of important papers on the application of group theory in quantum mechanics.  He was awarded the Nobel prize for physics jointly with Maria Mayer and J. H. D. Jensen in 1963.
 
1927 WERNER KARL HEISENBERG (Germany, 1901-1976) announced the "Unbestimmtheit Prinzip" (indeterminacy or uncertainty principle). He was awarded the Nobel prize for physics in 1932.
 
1927 CLINTON JOSEPH DAVISSON (USA, 1881-1958), and obtained electron diffraction from single crystals, and
LESTER HALBERT GERMER (USA, 1896-1971)
GEORGE PAGET THOMSON (England, 1892-1975) obtained powder diffraction patterns using electrons. Their work verified the existence of de Broglie waves.  Davisson and Thomson were awarded the Nobel prize for physics in 1937.
 
1928  EDWARD UHLER CONDON (USA, 1902-1974) and  solved the nuclear problem of alpha-particle emission by means of wave mechanics and derived the Geiger-Nuttall law.
RONALD WILFRID GURNEY (England, USA, 1898-1953) and, independently, 
GEORGE GAMOW (Russia, USA, 1904-1968)
 
1928 PAUL ADRIEN MAURICE DIRAC (England, 1902-1984) developed relativistic quantum mechanics and predicted the existence of the positron. He was awarded the Nobel prize for physics jointly with E. Schroedinger in 1933.
 
1928 CHANDRASEKHARA VENKATA RAMAN (India, 1888-1970) discovered the Raman effect.  This is the presence, in light scattered from molecules, of frequencies differing from that of the incident light by amounts characteristic of the scattering substance and independent of the incident frequency.  He was awarded the Nobel prize for physics in 1930.
 
1928  DMITRI VLADIMIROVICH SKOBELTSYN (Russia, b. 1892) obtained the first cloud-chamber photographs of cosmic rays.  These showed that the rays either were, or produced, many charged, high-energy particles.
 
1928 HANS GEIGER (Germany, 1882-1945) and developed the Geiger point counter (1913) into a greatly improved form, called the Geiger-Mueller counter.
W. MUELLER (Germany)
 
1928 WALTHER WILHELM GEORG FRANZ BOTHE (Germany, 1891-1957) and applied G-M tubes to make coincidence counters and other ingenious devices for cosmic-ray study. Bothe was awarded the Nobel price for physics jointly with M. Born in 1954.
W. KOLHOERSTER (Austria)
 
1929 OTTO STERN (Germany, USA, b. 1888) obtained crystal diffraction of a beam of helium atoms.
 
1930 W. BOTHE (Germany) and observed a puzzling penetrating "radiation" from beryllium bombarded with alpha particles.
H. BECKER (Germany)
 
1930 JACOB CLAY (Netherlands, 1882-1955) discovered that cosmic-ray intensity decreased in going toward the geomagnetic equator.  This latitude effect was investigated exhaustively by A. H. Compton, R. A. Millikan, and others.
 
1930 FREDRIK CARL MUELERTZ STOERMER (Norway, 1874-1957) applied his 1934 theory of the motion of charged particles in the magnetic field of the earth, originally developed to account for the aurora borealis, to cosmic rays. This theory of the cause of geomagnetic effects was greatly expanded in 1933 by
GEORGES LEMAITRE (Belgium,
                1894-1966) and
MANUEL SANDOVAL VALLARTA (Mexico, 1899-1977) Further theoretical work was done by
WILLIAM FRANCIS GRAY SWANN (England, USA, 1884-1962) and others.
 
1930-1933 IRA FORRY ZARTMAN (USA, b. 1899) and experimentally verified the Maxwell distribution law of molecular speeds.
C. C. Ko (China, USA)
 
1931 THOMAS HOPE JOHNSON (USA, 1899-1998) obtained crystal diffraction of a beam of hydrogen atoms.
 
1931 ROBERT JEMISON VAN DE GRAAFF (USA, 1901-1967) constructed the first reliable, high-voltage, electrostatic generator for nuclear research.
 
1931 WOLFGANG PAULI (Austria, Switzerland, 1900-1958) proposed a hypothesis of beta decay processes postulating that a "new," small, neutral particle was emitted simultaneously with the electron. 
 
1931 HAROLD CLAYTON UREY (USA, b. 1893) discovered deuterium and made the first heavy water. Urey was awarded the Nobel prize for chemistry in 1934.
FERDINAND GRAFT BRICKWEDDE (USA, b. 1903), and
GEORGE MOSELEY MURPHY (USA, b. 1903)
 
1932  ROY JAMES KENNEDY (USA, b. 1897) and sought to detect the eithe drift with a very stable and refined form of interferometer having arms of unequal length. Both the length and the time transformations of the special theory of relativity had to be used to accound for the null result.
EDWARD MOULTON THORNDIKE (USA, b. 1905)
 
1932  ERNEST ORLANDO LAWRENCE (USA, 1901-1958) and made the first cyclotron.   Lawrence  was awarded the Nobel prize for physics in 1939.
MILTON STANLEY LIVINGSTON (USA, 1905-1986)
 
1932 SIR JOHN DOUGLAS COCKCROFT (England, 1897-1967) and accomplished the transmutation of lithium by bombarding it with high-energy protons, and so obtained the first direct verification of Einstein's law of mass-enery equivalence. This was also the first time a high-voltage accelerator was used successfully to produce a nuclear reaction. They were awarded the Nobel prize for physics in 1951.
ERNEST THOMAS SINTON WALTON (Ireland, 1903-1995)
 
1932 JAMES CHADWICK (England, 1891-1974) discovered the neutron. This particel accounted for Bothe and Becker's penetrating "radiation."  He was awarded the Nobel prize for physics in 1935.
 
1932 BRUNO BENEDETTO ROSSI (Italy, USA, 1905-1993) found an initial increase with thickness in the cosmic-ray intensity "transmitted" by an absorber and explained this by cosmic-ray showers.  A transition to decreasing intensities was observed beyond a certain thickness.
 
1932 CARL DAVID ANDERSON (USA, 1905-1991) discovered the positron during cosmic-ray research. He was awarded the Nobel prize for physics jointly with V. F. Hess in 1936.
 
1933 PATRICK M. S. BLACKETT (England, 1897-1974) and obtained the first cloud-chamber photographs of electron-positron pair production.
GUISEPPE P. S. OCCHIALINI (England, 1907-1993)
 
1933 JEAN VALENTIN THIBAUD (France, 1901-1960) and observed the radiation produced by electron-positron annihilation. They also showed that the mass of the positron is equal to that of the electron.
FREDERIC JOLIOT (France, 
                1900-1958)
 
1933 THOMAS  HOPE JOHNSON (USA, 1899-1998) and  observed that the cosmic-ray intensity from the west exceeded that from the east. This east-west asymmetry shows that there is an excess of positively charged particles in the primary cosmic-ray beam.
JABEZ CURRY STREET (USA, 1906-1989)
 
1934 PAVEL ALEKSEJEVIC CHERENKOV (Russia, b. 1904) observed the weak, bluish glow in transparent substances when irradiated with high-energy beta particles. The theory of this Cherenkov radiation was given by
IGOR JEVGENEVIC TAMM (Russia, b. 1895) and
ILYA MICHAJLOVIC FRANK (Russia, b. 1908) three years later. These three scientists were jointly awarded the Nobel prize for physics in 1958.
 
1934 S. MOHOROVICIC (Yugoslavia) predicted the existence of a transitory non-nuclear "element" (later called positronium) preceding electron-positron annihilation.
 
1934 IRENE JOLIOT-CURIE (France, 1897-1956) and discovered artificial (induced) radioactivity.  They were awarded the Nobel prize for chemistry in 1935.
FREDERIC JOLIOT (France, 
                1900-1958)
 
1934 ENRICO FERMI (Italy, USA, 1901-1954) developed Pauli's theory of beta decay and named the "new" particle the neutrino (little neutron). It is postulated in Fermi's theory that the neutron is radioactive, disintegrating into a proton with the formation of an electron and a neutrino just before beta emission. He also began a series of experiments in collaboration with
  EDUARDO AMALDI (Italy, 1908-1989)
OSCAR D'AGOSTINO (Italy, 1901-1975) 
           
FRANCO RASETTI (Italy, USA, b. 1901) and
EMILIO GINO SEGRE (Italy, USA, b. 1905) to produce transuranic elements by irradiating uranium with neutrons. They were granted a patent on the graphite moderator in 1955. Fermi was awarded the Nobel prize for physics in 1938.
 
1935-1939 ISIDOR ISAAC RABI (Austria, USA, b. 1898) made precise determinations of nuclear magnetic moments in beams of atoms by his radio frequency resonance method. He was awarded the Nobel prize for physics in 1944.
 
1935 HIDEKI YUKAWA (Japan, 1907-1981) announced his theory of nuclear binding forces involving involving the postulate of a particle having a mass intermediate between that of the electron and the proton.  He was awarded the Nobel prize for physics in 1949.
 
1936 CARL DAVID ANDERSON (USA, 1905-1991) and discovered, during cosmic-ray research, a particle of the type postulated by Yukawa
They called it the "mesotron" (later changed to "meson").
SETH HENRY NEDDERMEYER (USA, b. 1907)
 
1936 MARIETTA BLAU (Austria, 1894-1970) was the first to use nuclear track plates.
 
1937 NIELS HENRIK DAVID BOHR (Denmark, 1885-1962) introduced the liquid-drop model of the nucleus. 
 
1938 IRENE JOLIOT-CURIE (France, 1897-1956) and found indications of the existence of lanthanum in uranium after it was irradiated with neutrons.
PAVLE SAVIC/SAVITCH (Yugoslavia, 1903-1994)
 
1938 OTTO HAHN (Germany, 1879-1968) and  discovered that bombarding uranium with neutrons produces alkali earth elements. Hahn was awarded the Nobel prize for chemistry in 1944.
FRITZ STRASSMANN (Germany, 1902-1980)
 
1939 LISE MEITNER (Austria, Germany, Sweden, 1878-1968) and proposed nuclear splitting to explain Hahn's results on the disintegration of uranium by neutrons and predicted the release of an enormous amount of enery per fission.
OTTO ROBERT FRISCH (Austria, Germany, England, 1904-1979)
 
1939 NIELS HENRIK DAVID BOHR (Denmark, 1885-1962) and developed the theory of nuclear fission.
JOHN ARCHIBALD WHEELER (USA, b. 1911)
 
1939 HANS ALBECHT BETHE (Germany, USA, b. 1906) and independently proposed two sets of nuclear reactions to account for stellar energies: the carbon cycle and the proton-proton chain.
CARL FRIEDRICH VON WEIZSAECKER (Germany, b. 1912)
 
1940 JOHN RAY DUNNING (USA, b. 1907), and showed that it is U235, the less abundant isotope of uranium, that is fissioned by slow neutrons.
EUGENE THEODORE BOOTH (USA, b. 1912), and
ARISTID V. GROSSE (Russia, USA, b. 1905)
 
1940 LOUIS LePRINCE-RINGUET (France, 1901-2000) obtained the first cloudchamber photograph of a meson-electron collision, from which the mass of the meson could be deduced.
 
1940 DONALD WILLIAM KERST (USA, 1911-1993) made the first betatron, an induction type accelerator.
 
1940 EDWIN MATTISON MCMILLAN (USA, 1907-1999) and produced the first transuranic element, neptunium; and 
PHILIP HAGUE ABELSON (USA, b. 1913)
GLENN THEODORE SEABORG (USA, 1912-1999), and prepared the second transuranic element, plutonium. McMillan and Seaborg were awarded the Nobel prize for chemistry in 1951.
EDWIN MATTISON MCMILLAN (USA, 1907-1999), and
JOSEPH WILLIAM KENNEDY (USA, b. 1917), and
ARTHUR CHARLES WAHL (USA, b. 1917)
 
1942 ENRICO FERMI (Italy, USA, 1901-1954) and associates built the first successful self-sustaining fission reactor. It was first put into operation on December 2 and operated at a power level of one-half watt. It was located in Chicago, Illinois.
LEO SZILARD (Hungary, Germany, USA, 1898-1964)
 
1945 J. ROBERT OPPENHEIMER (USA, 1904-1967) then Director of the Los Alamos Scientific Laboratory, and the many scientists engaged there in a "crash" program of basic nuclear research and development saw the culmination of their work in the detonation of the first nuclear bomb at Almagordo, New Mexico, on July 16.
 
1945 EDWIN MATTISON MCMILLAN (USA, 1907-1999) and independently proposed the principle of the synchrotron, the type of accelerator which produces very high-energy particles, as in the Cosmotron, Bevatron, etc.
VLADIMIR IOSIFOVICH VEKSLER (Russia, 1907-1966
 
1946 FELIX BLOCH (Switzerland, USA, 1905-1983) devised the magnetic induction method and, independently,
EDWARD MILLS PURCELL (USA, 1912-1997) originated the magnetic resonance absorption method for determining nuclear magnetic moments, using liquids or solids in bult (not beams). This led to the nuclear resonance spectrometer. They were awarded the Nobel prize for physics in 1952.
 
1947 POLYKARP KUSCH (Germany, USA, 1911-1993) made high precision determinations of the magnetic moment of the electron and found a small but theoretically significant difference between the predicted value and the experimental results. Kusch was awarded the Nobel prize for physics jointly with W. R. Lamb in 1955.
 
1947 WILLIS EUGENE LAMB, JR., (USA, b. 1913) and observed, during the course of spectral measurements of the fine structure of hydrogen in the microwave region, a small displacement (the "Lamb shift") of an energy level from its theoretical position as predicted by Dirac's quantum theory of the electron. Lamb was awarded the Nobel prize for physics jointly with P. Kusch in 1955.
ROBERT E. RETHERFORD (USA)
 
1947 HANS ALBECHT BETHE (Germany, USA, b. 1906)and, independently, explained the discrepancies found by Kusch and by Lamb as resulting from an interaction of electrons with the radiation field.  Schwinger was awarded the Nobel prize for physics jointly with R. P. Feynman and S. Tomonaga in 1965.
JULIAN SEYMOUR SCHWINGER (USA, 1918-1994)
 
1947 HARTMUT PAUL KALLMANN (Germany, USA, 1896-1978) and, independently, developed scintillation counters.
JOHN WESLEY COLTMAN (USA, b. 1915) and
FITZ-HUGH BALL MARSHALL (USA, b. 1912)
 
1947 CECIL FRANK POWELL (England, 1903-1969),  discovered the pi-meson. Powell was awarded the Nobel prize for physics in 1950.
GUISEPPE P. S. OCCHIALINI (England, 1907-1993), and 
CESARE MANSUETO GIULIO LATTES (Brazil, England, b. 1924)
 
1947 GEORGE DIXON ROCHESTER (England, 1908-2001) and  discovered V-particles and hyperons.
CLIFFORD CHARLES BUTLER (England, 1922-1999) 
 
1948 EUGENE GARDNER (USA, 1913-1950) and were the first to produce mesons in the laboratory.
CESARE MANSUETO GIULIO LATTES (Brazil, England, b. 1924)
 
1948-1950 WILLARD FRANK LIBBY (USA, 1908-1980) and collaborators developed the techniques of radiocarbon dating. He was awarded the Nobel prize for chemistry in 1960.
 
1949 MARIA GOEPPERT MAYER (Germany, USA, 1906-1972) and, independently,  developed the shell theory of the nucleus, which assumes a spherical distribution of nucleons.  Mayer and Jensen were awarded the Nobel prize for physics jointly with E. P. Wigner in 1963.
OTTO HAXEL (Germany, b. 1909),
JOHANNES HANS DANIEL JENSEN (Germany, 1907-1973), and
HANS EDWARD SUESS (Austria, Germany, USA, 1909-1993)
 
1950 ARTHUR HAWLEY SNELL (Canada, USA, b. 1911) and associates at the Oak Ridge National Laboratory and his associates at the Chalk River Laboratory experimentally verified that the free neutron is radioactive.
JOHN MICHAEL ROBSON (England, Canada, 1920-2000)
 
1950 Scientists began intensified research on light-element fusion reactions.
 
1951 MARTIN DEUTSCH (Austria, USA, 1917-2002) experimentally confirmed the prediction of the existence of positronium.
 
1952 Brookhaven National laboratory was the first to achieve the acceleration of particles to the giga-electron-volt energy range: 2.3-Gev protons.
 
1952 AAGE NIELS BOHR (Denmark, b. 1922) and  developed the unified (collective) shell model of the nucleus, which assumes a nonspherical nuclear core.  The possibility of a distorted core had been suggested in 1950 by
BENJAMIN ROY MOTTELSON (Denmark b. 1926)
LEO JAMES RAINWATER (USA, 1917-1986).
 
1952 DONALD ARTHUR GLASER (USA, b. 1926) made the first bubble chanber. He was awarded the Nobel prize for physics in 1960.
 
1952 The first large-scale, terrestrial thermonuclear reaction was produced when a "hydrogen fusion device" was tested at Einewetok atoll on November 1.
 
1953 MURRAY GELL-MANN (USA, b. 1929) introduced the strangeness numbers for nucleons, mesons, and hyperons, and found that strangeness is conserved in strong interactions.
 
1953  ROBERT HOFSTADTER (USA, 1915-1990) and collaborators started a series of experiments on the scattering of high-energy electrons by atoms.  The results led to the determination of the charge distribution and structure of nuclei and nucleons.  Hofstadter was awarded the Nobel prize for physics jointly with R. L. Mossbauer in 1961.
 
1954 JAMES POWER GORDON (USA, b. 1928), made the first maser [molecular (formerly, microwave) amplification by stimulated emission of radiation]. In this device, many molecules which have been put into high entery states are induced to emit their energy as radiation by a weak incoming signal of the same frequency. Townes was awarded the Nobel prize for physics jointly with N. Basov and A. Prokhorv in 1964.
H. J. ZEIGER (USA, b. 1925) and 
CHARLES HARD TOWNES (USA, b. 1915)
 
1955  OWEN CHAMBERLAIN (USA, b. 1920), and created proton-antiproton pairs. Chamberlain and Segre were awarded the Nobel prize for physics in 1959.
EMILIO GINO SEGRE (Italy, USA, 1905-1989), and
CLYDE EDWARD WIEGAND (USA, b. 1915), and 
THOMAS JOHN YPSILANTIS (USA, b. 1928)
 
1956 LUIS WALTER ALVAREZ (USA, 1911-1988) and collaborators accomplished cold fusion of deuterium with the negative mu-meson as a catalyst.
 
1956 JOHN BARDEEN (USA, 1908-1991),  were awarded the Nobel prize for physics in recognition of their work in theory of the solid state, particularly semiconductors. 
WALTER HOUSER BRATTAIN (China, USA, 1902-1987), and 
WILLIAM SHOCKLEY (England, USA, 1910-1989)
 
1956 FREDERIC REINES (USA, b. 1915) and and collaborators experimentally confirmed the existence of the neutrino.
CLYDE LORRAIN COWAN, JR. (USA, 1919-1974)
 
1956 The world's first full-scale nuclear power plant was put into operation on October 17 at Calder Hall, England.  The gas-cooled reactors develop 360 megawatts of thermal power to deliver 78 megawatts of electrical power.
 
1956  TSUNG DAO LEE (CHINA, USA, b. 1926) and  deduced theoretically that the law of conservation of parity (the invariance of spatial inversion) is invalid for weak interactions.  They were awarded the Nobel prize for physics in 1957.
CHEN NING YANG (China, USA, b. 1922)
 
1956 CHINN-SHIUNG Wu (China, USA, b. 1915) and collaborators performed the first experiment that demonstrated the violation of conservation of parity. They observed the beta emission from Co^60 at very low temperatures.
 
1957  JOHN BARDEEN (USA, 1908-1991), announced the first comprehensive theory of superconductivity.
LEON N. COOPER (USA, b. 1930) and
JOHN ROBERT SCHRIEFFER (USA, b. 1931)
 
1958 CHARLES HARD TOWNES (USA, b. 1915) employed maser beams in the most precise ether-drift experiment yet performed. The results showed that if the effect exists, it is less than one-thousandth of the earth's orbital speed or less than one ten-millionth of the speed of light. The precision in the comparison of the frequencies of the masers was about one part in a million million.
JOHN PERRY CEDARHOLM (USA, b. 1927), 
GEORGE FRANCIS BLAND (USA, b. 1927), and 
BYRON LUTHER HAVENS (USA, b. 1914)
 
1958  RUDOLPH L. MOSSBAUER (Germany, b. 1929) predicted and found an extremely small frequency spread in the emission of low-energy gamma rays from nuclei bound in a crystal lattice. This effect results from giving the gamma-ray recoil momentum to the whole lattice instead of to an individual nucleus. The effect provides a very high precision frequency standard suitable for testing several predictions of the special and general theories of relativity. He was awarded the Nobel prize for physics jointly with R. Hofstadter in 1961.
 
1959 JAMES ALFRED VAN ALLEN (USA, b. 1914) showed from the data obtained from 
instruments carried by artificial satellites that the earth is encircled by two zones, called  VAN ALLEN radiation belts, of high-energy charged particles which are trapped by the earth's magnetic field.
 
1960 THEODORE HAROLD MAIMAN (USA, b. 1927) made the first ruby laser.
 
1960 ALI JAVAN (Iran, USA, b. 1928) made the first helium-neon laser.
 
1960 VERNON WILLARD HUGHES (USA, b. 1921),  made and studied muonium,a short-lived atom having a positive mu-meson nucleus and an orbiting electron.
D. W. McCOLM, KLAUS OTTO Ziock (Germany, USA, b. 1925) and
R. PREPOST
 
1962 BRIAN D. JOSEPHSON (England) discovered and theoretically analyzed a number of unexpected phenomena occurring at a "Josephson junction," an arrangement consisting of two superconductors separated by a very thin layer of insulating material. 
 
1965 JEROME V. V. KASPER and made the first chemical laser, a device in which pumping energy is supplied by chemical reactions instead of by an external source of power.
GEORGE CLAUDE PIMENTEL (USA, 1922-1989)