Timeline of quantum mechanics, molecular physics, atomic physics, nuclear physics, and particle physics

Timeline of quantum mechanics, molecular physics, atomic physics, nuclear physics, and particle physics

Timeline of quantum mechanics, molecular physics, atomic physics, nuclear physics, and particle physics

440 BC Democritus speculates about fundamental indivisible particles---calls them "atoms"

1766 Henry Cavendish discovers and studies hydrogen

1778 Carl Scheele and Antoine Lavoisier discover that air is composed mostly of nitrogen and oxygen

1781 Joseph Priestley creates water by igniting hydrogen and oxygen

1800 William Nicholson and Anthony Carlisle use electrolysis to separate water into hydrogen and oxygen

1803 John Dalton introduces atomic ideas into chemistry and states that matter is composed of atoms of different weights

1811 Amedeo Avogadro claims that equal volumes of gases should contain equal numbers of molecules

1832 Michael Faraday states his laws of electrolysis

1871 Dmitri Ivanovich Mendeleev systematically examines the periodic table and predicts the existence of gallium, scandium, and germanium

1873 Johannes van der Waals introduces the idea of weak attractive forces between molecules

1885 Johann Balmer finds a mathematical expression for observed hydrogen line wavelengths

1887 Heinrich Hertz discovers the photoelectric effect

1894 Lord Rayleigh and William Ramsay discover argon by spectroscopically analyzing the gas left over after nitrogen and oxygen are removed from air

1895 William Ramsay discovers terrestrial helium by spectroscopically analyzing gas produced by decaying uranium

1896 Antoine Becquerel discovers the radioactivity of uranium

1896 Pieter Zeeman studies the splitting of sodium D lines when sodium is held in a flame between strong magnetic poles

1897 Joseph Thomson discovers the electron

1898 William Ramsay and Morris Travers discover neon, krypton, and xenon

1898 Marie Curie and Pierre Curie isolate and study radium and polonium

1899 Ernest Rutherford discovers that uranium radiation is composed of positively charged alpha particles and negatively charged beta particles

1900 Paul Villard discovers gamma-rays while studying uranium decay

1900 Johannes Rydberg refines the expression for observed hydrogen line wavelengths

1900 Max Planck states his quantum hypothesis and blackbody radiation law

1902 Philipp Lenard observes that maximum photoelectron energies are independent of illuminating intensity but depend on frequency

1902 Theodor Svedberg suggests that fluctuations in molecular bombardment cause the Brownian motion

1905 Albert Einstein explains the photoelectric effect

1906 Charles Barkla discovers that each element has a characteristic X-ray and that the degree of penetration of these X-rays is related to the atomic weight of the element

1909 Hans Geiger and Ernest Marsden discover large angle deflections of alpha particles by thin metal foils

1909 Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms

1911 Ernest Rutherford explains the Geiger-Marsden experiment by invoking a nuclear atom model and derives the Rutherford cross section

1912 Max von Laue suggests using lattice solids to diffract X-rays

1912 Walter Friedrich and Paul Knipping diffract X-rays in zinc blende

1913 William Henry Bragg and William Lawrence Bragg work out the Bragg condition for strong X-ray reflection

1913 Henry Moseley shows that nuclear charge is the real basis for numbering the elements

1913 Niels Bohr presents his quantum model of the atom

1913 Robert Millikan measures the fundamental unit of electric charge

1913 Johannes Stark demonstrates that strong electric fields will split the Balmer spectral line series of hydrogen

1914 James Franck and Gustav Hertz observe atomic excitation

1914 Ernest Rutherford suggests that the positively charged atomic nucleus contains protons

1915 Arnold Sommerfeld develops a modified Bohr atomic model with elliptic orbits to explain relativistic fine structure

1916 Gilbert Lewis and Irving Langmuir formulate an electron shell model of chemical bonding

1917 Albert Einstein introduces the idea of stimulated radiation emission

1921 Alfred Lande introduces the Lande g-factor

1922 Arthur Compton studies X-ray photon scattering by electrons

1922 Otto Stern and Walter Gerlach show "space quantization"

1923 Louis de Broglie suggests that electrons may have wavelike properties

1924 Wolfgang Pauli states the quantum exclusion principle

1924 John Lennard-Jones proposes a semiempirical interatomic force law

1924 Satyendra Bose and Albert Einstein introduce Bose-Einstein statistics

1925 George Uhlenbeck and Samuel Goudsmit postulate electron spin

1925 Pierre Auger discovers the Auger autoionization process

1925 Werner Heisenberg, Max Born, and Pascual Jordan formulate quantum matrix mechanics

1926 Erwin Schr�dinger states his nonrelativistic quantum wave equation and formulates quantum wave mechanics

1926 Erwin Schr�dinger proves that the wave and matrix formulations of quantum theory are mathematically equivalent

1926 Oskar Klein and Walter Gordon state their relativistic quantum wave equation

1926 Enrico Fermi discovers the spin-statistics connection

1926 Paul Dirac introduces Fermi-Dirac statistics

1927 Clinton Davission, Lester Germer, and George Thomson confirm the wavelike nature of electrons

1927 Werner Heisenberg states the quantum uncertainty principle

1927 Max Born interprets the probabilistic nature of wavefunctions

1928 Chandrasekhara Raman studies optical photon scattering by electrons

1928 Paul Dirac states his relativistic electron quantum wave equation

1928 Charles G. Darwin and Walter Gordon solve the Dirac equation for a Coulomb potential

1929 Oskar Klein discovers the Klein paradox

1929 Oskar Klein and Y. Nishina derive the Klein-Nishina cross section for high energy photon scattering by electrons

1929 N.F. Mott derives the Mott cross section for the Coulomb scattering of relativistic electrons

1930 Paul Dirac introduces electron hole theory

1930 Erwin Schr�dinger predicts the zitterbewegung motion

1930 Fritz London explains van der Waals forces as due to the interacting fluctuating dipole moments between molecules

1931 John Lennard-Jones proposes the Lennard-Jones interatomic potential

1931 Irene Joliot-Curie and Fr�d�ric Joliot observe but misinterpret neutron scattering in paraffin

1931 Wolfgang Pauli puts forth the neutrino hypothesis to explain the apparent violation of energy conservation in beta decay

1931 Linus Pauling discovers resonance bonding and uses it to explain the high stability of symmetric planar molecules

1931 Paul Dirac shows that charge conservation can be explained if magnetic monopoles exist

1931 Harold Urey discovers deuterium using evaporation concentration techniques and spectroscopy

1932 John Cockcroft and Thomas Walton split lithium and boron nuclei using proton bombardment

1932 James Chadwick discovers the neutron

1932 Werner Heisenberg presents the proton-neutron model of the nucleus and uses it to explain isotopes

1932 Carl Anderson discovers the positron

1933 Max Delbruck suggests that quantum effects will cause photons to be scattered by an external electric field

1934 Irene Joliot-Curie and Fr�d�ric Joliot bombard aluminum atoms with alpha particles to create artificially radioactive phosphorus-30

1934 Leo Szilard realizes that nuclear chain reactions may be possible

1934 Enrico Fermi formulates his theory of beta decay

1934 Lev Davidovich Landau tells Edward Teller that nonlinear molecules may have vibrational modes which remove the degeneracy of an orbitally degenerate state

1934 Enrico Fermi suggests bombarding uranium atoms with neutrons to make a 93 proton element

1934 Pavel Alekseyevich Cherenkov reports that light is emitted by relativistic particles traveling in a nonscintillating liquid

1935 Hideki Yukawa presents a theory of strong interactionss and predicts mesons

1935 Albert Einstein, Boris Podolsky, and Nathan Rosen put forth the EPR paradox

1935 Niels Bohr presents his analysis of the EPR paradox

1936 Eugene Wigner develops the theory of neutron absorption by atomic nuclei

1936 Hans Jahn and Edward Teller present their systematic study of the symmetry types for which the Jahn-Teller effect is expected

1937 H. Hellmann finds the Hellmann-Feynman theorem

1937 Seth Neddermeyer, Carl Anderson, J.C. Street, and E.C. Stevenson discover muons using cloud chamber measurements of cosmic rays

1939 Richard Feynman finds the Hellmann-Feynman theorem

1939 Otto Hahn and Fritz Strassman bombard uranium salts with thermal neutrons and discover barium among the reaction products

1939 Lise Meitner and Otto Frisch determine that nuclear fission is taking place in the Hahn-Strassman experiments

1942 Enrico Fermi makes the first controlled nuclear chain reaction

1942 Ernst Stuckelberg introduces the propagator to positron theory and interprets positrons as negative energy electrons moving backwards through spacetime

1943 Sin-Itiro Tomonaga publishes his paper on the basic physical principles of quantum electrodynamics

1947 Willis Lamb and Robert Retheford measure the Lamb-Retheford shift

1947 Cecil Powell, C.M.G. Lattes, and G.P.S. Occhialini discover the pi-meson by studying cosmic ray tracks

1947 Richard Feynman presents his propagator approach to quantum electrodynamics

1948 Hendrik Casimir predicts a rudimentary attractive Casimir force on a parallel plate capacitor

1951 Martin Deutsch discovers positronium

1952 David Bohm propose his interpretation of quantum mechanics

1953 R. Wilson observes Delbruck scattering of 1.33 MeV gamma-rays by the electric fields of lead nuclei

1954 Chen Ning Yang and Robert Mills investigate a theory of hadronic isospin by demanding local gauge invariance under isotopic spin space rotations---first non-Abelian gauge theory

1955 Owen Chamberlain, Emilio Segre, Clyde Wiegand, and Thomas Ypsilantis discover the antiproton

1956 Frederick Reines and Clyde Cowan detect antineutrinos

1956 Chen Ning Yang and Tsung Lee propose parity violation by the weak nuclear force

1956 Chien Shiung Wu discovers parity violation by the weak force in decaying cobalt

1957 Gerhart Luders proves the CPT theorem

1957 Richard Feynman, Murray Gell-Mann, Robert Marshak, and Ennackel Sudarshan propose a variational approximation (VA) Lagrangian for weak interactions

1958 Marcus Sparnaay experimentally confirms the Casimir effect

1959 Yakir Aharonov and David Bohm predict the Aharonov-Bohm effect

1960 R.G. Chambers experimentally confirms the Aharonov-Bohm effect

1961 Murray Gell-Mann and Yuval Ne'eman discover the Eightfold Way patterns---SU(3) group

1961 Jeffery Goldstone considers the breaking of global phase symmetry

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

1963 Murray Gell-Mann and George Zweig propose the quark/aces model

1964 Peter Higgs considers the breaking of local phase symmetry

1964 John Stewart Bell shows that all local hidden variable theories must satisfy Bell's inequality

1964 Val Fitch and James Cronin observe CP violation by the weak force in the decay of K mesons

1967 Steven Weinberg puts forth his electroweak model of leptons

1969 J.C. Clauser, M. Horne, A. Shimony, and R. Holt propose a polarization correlation test of Bell's inequality

1970 Sheldon Glashow, John Iliopoulos, and Luciano Maiani propose the charm quark

1971 Gerard 't Hooft shows that the Glashow-Salam-Weinberg electroweak model can be renormalized

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

1973 David Politzer proposes the asymptotic freedom of quarks

1974 Burton Richter and Samuel Ting discover the psi meson implying the existence of the charm quark

1975 Martin Perl discovers the tauon

1977 S.W. Herb finds the upsilon resonance implying the existence of the beauty quark

1982 A. Aspect, J. Dalibard, and G. Roger perform a polarization correlation test of Bell's inequality that rules out conspiratorial polarizer communication

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

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