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 Bragg and 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 Schršdinger states his nonrelativistic quantum wave equation
and formulates quantum wave mechanics - 1926 Erwin Schršdinger 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 Schršdinger 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 FrŽdŽric 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 FrŽdŽric 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 interactions 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 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 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