Quantum Theory Timeline, 1490-1989
1490: Leonardo da Vinci describes capillary action
1581: Galileo Galilei notices the timekeeping property of the pendulum
1589: Galileo Galilei uses balls rolling on inclined planes to show that different weights fall with the same acceleration
1658: Christian Huygens experimentally discovers that balls placed anywhere inside an inverted cycloid reach the lowest point of the cycloid in the same time and thereby experimentally shows that the cycloid is the isochrone
1668: John Wallis suggests the law of conservation of momentum
1690: James Bernoulli shows that the cycloid is the solution to the isochrone problem
1691: Johann Bernoulli shows that the catenary curve has the lowest center of gravity that any chain hung from two fixed points can have
1696: Johann Bernoulli shows that the cycloid is the solution to the brachistochrone problem
1714: Brook Taylor derives the fundamental frequency of a stretched vibrating string in erms of its tension and mass per unit length by solving an ordinary differential equation
1733: Daniel Bernoulli derives the fundamental frequency and harmonics of a hanging chain by solving an ordinary differential equation
1734: Daniel Bernoulli solves the ordinary differental equation for the vibrations of an elastic bar clamped at one end
1739: Leonhard Euler solves the ordinary differential equation for a forced harmonic oscillator and notices the resonance phenomenon
1742: Colin Maclaurin discovers his uniformly rotating self-gravitating spheroids
1747: Pierre-Louis Moreau de Maupertuis applies minimum principles to mechanics
1759: Leonhard Euler solves the partial differential equation for the vibration of a rectangular drum
1764:Leonhard Euler examines the partial differential equation for the vibration of a circular drum and finds one of the Bessel function solutions
1766: Henry Cavendish discovers and studies hydrogen
1778:Carl Scheele and Antoine-Laurent Lavoisier discover that air is composed mostly of nitrogen and oxygen
1781: Joseph Priestley creates water by igniting hydrogen and oxygen
1788: Joseph Lagrange presents Lagrange's equations of motion in MTcanique Analytique
1789: Antoine-Laurent Lavoisier states the law of conservation of mass
1800:m 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
1821:William Hamilton begins his analysis of Hamilton's characteristic function
1832: Michael Faraday states his laws of electrolysis
1834: Carl Jacobi discovers his uniformly rotating self-gravitating ellipsoids
1834: John Russell observes a nondecaying solitary water wave in the Union Canal near Edinburgh and uses a water tank to study the dependence of solitary water wave velocities on wave amplitude and water depth
1835: Gaspard de Coriolis examines motion on a spinning surface deduces the Coriolis effect
1835:William Hamilton states Hamilton's canonical equations of motion
1842: Christian Doppler examines the Doppler shift of sound
1847: Hermann Helmholtz formally states the law of conservation of energy
1851: Jean-Bernard Foucault shows the Earth's rotation with a huge pendulum
1853: Scattering of electrons off nuclei reveals a charge density distributioinside protons, and even neutrons. Description of this electromagnetic structure of protons and neutrons suggests some kind of internal structure to these objects, though they are still regarded as fundamental particles. (1853 - 1857)
1871: Dmitri Mendeleyev 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.
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: Theodor Svedberg suggests that fluctuations in molecular bombardment cause the Brownian motion
1902: Philipp Lenard observes that maximum photoelectron energies are independent of illuminating intensity but depend on frequency
1902: James Jeans finds the length scale required for gravitational pertrubatations to grow in a static nearly homogeneous medium
1905: Albert Einstein, one of the few scientists to take Planck's ideas seriously, proposes a quantum of light (the photon) which behaves like a particle. Einstein's other theories explained the equivalence of mass and energy, the particle-wave duality of photons, the equivalence principle, and special relativity.
1905: Albert Einstein, light-quantum theory for photoelectric law
1905: Albert Einstein explains the photoelectric effect
1905: Albert Einstein, one of the few scientists to take Planck's ideas seriously,
proposes a quantum of light (the photon) which behaves like a particle. Einstein's
other theories explained the equivalence of mass and energy, the particle-wave
duality of photons, the equivalence principle, and special relativity.
1906: Albert Einstein, quantum explanation of specific heat laws for solids
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
1909: Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms
1909: Hans Geiger and Ernest Marsden, under the supervision of Ernest Rutherford, scatter alpha particles off a gold foil and observe large angles of scattering, suggesting that atoms have a small, dense, positively charged nucleus.
1911: Ernest Rutherford infers the nucleus as the result of the alpha-scattering experiment performed by Hans Geiger and Ernest Marsden.
1912: Albert Einstein explains the curvature of space-time.
1912: Bohr begins work on quantum theory of atom.
1912: Walter Friedrich and Paul Knipping diffract X-rays in zinc blende
1912: Max von Laue suggests using lattice solids to diffract X-rays
1913: Johannes Stark demonstrates that strong electric fields will split the Balmer spectral line series of hydrogen
1913: Robert Millikan measures the fundamental unit of electric charge
1913: Henry Moseley shows that nuclear charge is the real basis for numbering the elements
1913: William Bragg and Lawrence Bragg work out the Bragg condition for strong X-ray reflection
1913: Niels Bohr succeeds in constructing a theory of atomic structure based on quantum ideas.
1913: Bohr published his model of the atom, based on energy states described by one quantum number
1914: Ernest Rutherford suggests that the positively charged atomic nucleus contains protons
1914: James Franck and Gustav Hertz observe atomic excitation
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
1916: Arnold Sommerfeld, Further atomic quantum numbers and fine structure of spectra, fine structure constant
1917: Albert Einstein introduces the idea of stimulated radiation emission
1919: Ernest Rutherford finds the first evidence for a proton.
1921: Alfred LandT introduces the Lande g-factor
1921: James Chadwick and E.S. Bieler conclude that some strong force holds the nucleus together.
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
1923: Arthur Compton discovers the quantum (particle) nature of x rays, thus confirming photons as particles.
1924: Louis de Broglie proposes that matter has wave properties.
1924: Satyendra Bose and Albert Einstein introduce Bose-Einstein statistics
1924: John Lennard-Jones proposes a semiempirical interatomic force law
1924: Wolfgang Pauli states the quantum exclusion principle
1924: Albert Einstein, statistical physics of quantum boson molecular gas
1924: Louis de Broglie proposes that matter has wave properties.
1925: George Uhlenbeck and Samuel Goudsmit postulate electron spin
1925: Wolfgang Pauli formulates the exclusion principle for electrons in an atom. .
1925: Werner Heisenberg, Max Born, and Pascual Jordan formulate quantum matrix
mechanics
1925: Walther Bothe and Hans Geiger demonstrate that energy and mass are conserved
in atomic processes.
1925: Pauli proposed the Exclusion Principle (no two electrons in an atom can have
the same set of quantum numbers)
1925: Paul Dirac, q-number theory of general quantum mechanics
1925: Born and Jordan, matrix interpretation of Heisenberg's quantum mechanics
1925: Werner Heisenberg, transition amplitude theory of quantum mechanics
1925: Pierre Auger discovers the Auger autoionization process
1925: Walther Bothe and Hans Geiger demonstrate that energy and mass are conserved
in atomic processes.
1926: Erwin Schoedinger proves that the wave and matrix formulations of quantum
theory are mathematically equivalent
1926: Erwin Schroedinger develops wave mechanics, which describes the behavior of
quantum systems for bosons. Max Born gives a probability interpretation of quantum
mechanics. G.N. Lewis proposes the name "photon" for a light quantum.
1926: Paul Dirac introduces Fermi-Dirac statistics
1926: Oskar Klein and Walter Gordon state their relativistic quantum wave equation
1926: Erwin Schroenger states his nonrelativistic quantum wave equation and
formulates quantum wave mechanics
1926: Dirac, Jordan, canonical transformation theory for quantum mechanics
1926: Enrico Fermi discovers the spin-statistics connection
1927: Certain materials had been observed to emit electrons (beta decay). Since
both the atom and the nucleus have discrete energy levels, it is hard to see how
electrons produced in transition could have a continuous spectrum (see 1930 for an
answer.)
1927: Friedrich Hund: quantum tunneling
1927: Heitler and London, quantum theory can explain chemical bonding
1927: Niels Bohr, Copenhagen interpretation of Quantum Mechanics
1927: Werner Heisenberg formulates the uncertainty principle: the more you know mabout a particle's energy, the less you know about the time of the energy (and vice versa.) The same uncertainty applies to momenta and coordinates.
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: Condon, Gamow, Gurney, alpha emission is due to quantum tunnelling
1928: Jordan, Pauli, quantum field theory of free fields
1928: Heisenberg, Weyl, group representation theory in quantum mechanics
1928: Dirac developed the relativistic quantum theory
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
1928: Paul Dirac combines quantum mechanics and special relativity to describe the electron.
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
1929: Heisenberg, Pauli, interacting quantum field theory and divergences
1929: Oskar Klein discovers the Klein paradox
1930: Erwin Schr÷dinger predicts the zitterbewegung motion
1930: Wolfgang Pauli suggests the neutrino to explain the continuous electron
spectrum for beta decay.
1930: Hartree and Fock, multi-particle quantum mechanics
1930: Fritz London explains van der Waals forces as due to the interacting
fluctuating dipole moments between molecules
1930: Paul Dirac introduces electron hole theory
1930: Wolfgang Pauli suggests the neutrino to explain the continuous electron
spectrum for beta decay.
1930: Quantum mechanics and special relativity are well established. There are just
three fundamental particles: protons, electrons, and photons. Max Born, after
learning of the Dirac equation, said, "Physics as we know it will be over in six
months."
1931: Irene Joliot-Curie and F. Joliot-Curie observe but misinterpret neutron
scattering in parafin
1931: Harold Urey discovers deuterium using evaporation concentration techniques
and spectroscopy
1931: Paul Dirac shows that charge conservation can be explained if magnetic
monopoles exist
1931: Linus Pauling discovers resonance bonding and uses it to explain the high
stability of symmetric planar molecules
1931: Wolfgang Pauli puts forth the neutrino hypothesis to explain the apparent
violation of energy conservation in beta decay
1931: James Chadwick discovers the neutron. The mechanisms of nuclear binding and
decay become primary problems.
1931: Paul Dirac realizes that the positively-charged particles required by his
equation are new objects (he calls them "positrons"). They are exactly like
electrons, but positively charged. This is the first example of antiparticles.
1931: Paul Dirac, magnetic monopoles can explain quantum of charge
1931: John Lennard-Jones proposes the Lennard-Jones interatomic potential
1931: Eugene Wigner, symmetry in quantum mechanics
1931: James Chadwick discovers the neutron. The mechanisms of nuclear binding and
decay become primary problems.
1932: Werner Heisenberg presents the proton-neutron model of the nucleus and uses
it to explain isotopes
1932: John Cockcroft and Thomas Walton split lithium and boron nuclei using proton
bombardment
1932: Carl Anderson discovers the positron
1933: Enrico Fermi puts forth a theory of beta decay that introduces the weak
interaction. This is the first theory to explicitly use neutrinos and particle
flavor changes.
1933: Hideki Yukawa combines relativity and quantum theory to describe nuclear interactions by an exchange of new particles (mesons called "pions") between protons and neutrons. From the size of the nucleus, Yukawa concludes that the mass of the conjectured particles (mesons) is about 200 electron masses. This is the beginning of the meson theory of nuclear forces. (1933 - 1934)
1933: Max Delbrnck suggests that quantum effects will cause photons to be scattered by an external electric field
1934: Pavel Cerenkov reports that light is emitted by relativistic particles traveling in a nonscintillating liquid
1934: Lev Landau tells Edward Teller that nonlinear molecules may have vibrational modes which remove the degeneracy of an orbitally
1934: I. Joliot-Curie and F. Joliot-Curie bombard aluminum atoms with alpha particles to create artificially radioactive phosphorus-30
1934: Enrico Fermi suggests bombarding uranium atoms with neutrons to make a 93 proton element
1934: Leo Szilard realizes that nuclear chain reactions may be possible
1935: Einstein, Podolsky, Rosen, EPR Paradox of non-locality in quantum mechanics
1935: Erwin Schroedinger, quantum cat paradox
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
1937: A particle of 200 electron masses is discovered in cosmic rays. While at first physicists thought it was Yukawa's pion, it was later discovered to be a muon.
1938: E.C.G. Stuckelberg observes that protons and neutrons do not decay into any combination of electrons, neutrinos, muons, or their antiparticles. The stability of the proton cannot be explained in terms of energy or charge conservation; he proposes that heavy particles are independently conserved.
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
1941: C. Moller and Abraham Pais introduce the term "nucleon" as a generic term for protons and neutrons.
1942: Ernst Stnckelberg introduces the propagator to positron theory and interprets positrons as negative energy electrons moving
1942: Enrico Fermi makes the first controlled nuclear chain reaction
1943: Sin-Itiro Tomonaga publishes his paper on the basic physical principles of quantum electrodynamics
1946: Physicists realize that the cosmic ray particle thought to be Yukawa's meson is instead a "muon," the first particle of the second generation of matter particles to be found. This discovery was completely unexpected -- I.I. Rabi comments "who ordered that?" The term "lepton" is introduced to describe objects that do not interact too strongly (electrons and muons are both leptons).
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 bystudying cosmic ray tracks
1947: Physicists develop procedures to calculate electromagnetic properties of electrons, positrons, and photons. Introduction of Feynman diagrams.
1947: A meson that does interact strongly is found in cosmic rays, and is determined to be the pion.
1947: Richard Feynman presents his propagator approach to quantum electrodynamics
1948: Richard Feynman, path integral approach to quantum theory
1948: The Berkeley synchro-cyclotron produces the first artificial pions.
1948: Hendrik Casimir predicts a rudimentary attractive Casimir force on a parallel
plate capacitor
1949: Enrico Fermi and C.N. Yang suggest that a pion is a composite structure of a
nucleon and an anti-nucleon. This idea of composite particles is quite radical.
1949: Discovery of K+ via its decay.
1950: The neutral pion is discovered.
1951: Two new types of particles are discovered in cosmic rays. They are discovered
by looking a V-like tracks and reconstructing the electrically-neutral object that
must have decayed to produce the two charged objects that left the tracks. The
particles were named the lambda0 and the K0.
1951: Martin Deutsch discovers positronium
1952: Discovery of particle called delta: there were four similar particles
(delta++, delta+, delta0, and delta-.)
1953: The beginning of a "particle explosion" -- a true proliferation of particles.
1953: R. Wilson observes Delbrnck scattering of 1.33 MeV gamma-rays by the electric
fields of lead nuclei
1953: The beginning of a "particle explosion" -- a true proliferation of particles.
1953: Scattering of electrons off nuclei reveals a charge density distribution
inside protons, and even neutrons. Description of this electromagnetic structure of
protons and neutrons suggests some kind of internal structure to these objects,
though they are still regarded as fundamental particles.
1954: C.N. Yang and Robert Mills develop a new class of theories called "gauge
theories." Although not realized at the time, this type of theory now forms the
basis of the Standard Model.
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 force
1956: Chien Shiung Wu discovers parity violation by the weak force in decaying
cobalt
1957: John Wheeler discusses the breakdown of classical general relativity near
singularities and the need for quantum gravity
1957: Julian Schwinger, Sidney Bludman, and Sheldon Glashow, in separate papers,
suggest that all weak interactions are mediated by charged heavy bosons, later
called W+ and W-. Actually, it was Yukawa who first discussed boson exchange twenty
years earlier, but he proposed the pion as the mediator of the weak force.
1957: Richard Feynman, Murray Gell-Mann, Robert Marshak, and Ennackel Sudarshan propose a V-A Lagrangian for weak interactions
1957: John Wheeler discusses the breakdown of classical general relativity near singularities and the need for quantum gravity
1957: Gerhart Lnders proves the CPT theorem
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
1961: As the number of known particles keep increasing, a mathematical classification scheme to organize the particles (the group SU(3)) helps physicists recognize patterns of particle types.
1962: Experiments verify that there are two distinct types of neutrinos (electron and muon neutrinos). This was earlier inferred from theoretical considerations.
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: Val Fitch and James Cronin observe CP violation by the weak force in the decay of K mesons
1964: J.S. Bell shows that all local hidden variable theories must satisfy Bell's inequality
1964: Peter Higgs considers the breaking of local phase symmetry
1965: Nobel Prize for Physics, "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles". Sin-Itiro Tomonaga, 1/3 Prize, Tokyo University of Education Tokyo Japan (Japan); Julian Schwinger Harvard University Cambridge, MA, USA Richard P. Feynman California Institute of Technology (Caltech) Pasadena, CA, USA (1918-1988).
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
1973: Edward Tryon proposes that the universe may be a large scale quantum mechanical vacuum fluctuation where positive mass-energy
1974: Burton Richter and Samuel Ting discover the psi meson implying the existence of the charm quark
1974: Stephen Hawking applies quantum field theory to black hole spacetimes and
shows that black holes will radiate particles with
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 Wpm and Z0 intermediate vector bosons
1989: The Z0 intermediate vector boson resonance width indicates three quark-lepto generations
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