6th - 2nd Century BCEKanada (philosopher) proposes thatanu is an indestructible particle of matter, an "atom"; anu is an abstraction and not observable.[1]
430 BCE[2]Democritus speculates about fundamental indivisible particles—calls them "atoms"
1906Charles Barkla discovers that each element has a characteristicX-ray and that the degree of penetration of these X-rays is related to theatomic weight of the element
1924Louis de Broglie suggests that electrons may have wavelike properties in addition to their 'particle' properties; thewave–particle duality has been later extended to all fermions and bosons.
1927Charles Drummond Ellis (along withJames Chadwick and colleagues) finally establish clearly that the beta decay spectrum is in fact continuous and not discrete, posing a problem that will later be solved by theorizing (and later discovering) the existence of theneutrino.
1942Enrico Fermi makes the first controlled nuclear chain reaction
1942Ernst Stueckelberg introduces the propagator to positron theory and interprets positrons as negative energy electrons moving backwards through spacetime
1964François Englert,Robert Brout,Peter Higgs,Gerald Guralnik,C. R. Hagen, andTom Kibble postulate that a fundamental quantum field, now called theHiggs field, permeates space and, by way of theHiggs mechanism, provides mass to all the elementary subatomic particles that interact with it. While the Higgs field is postulated to confer mass on quarks and leptons, it represents only a tiny portion of the masses of other subatomic particles, such as protons and neutrons. In these, gluons that bind quarks together confer most of the particle mass. The result is obtained independently by three groups: François Englert and Robert Brout; Peter Higgs, working from the ideas of Philip Anderson; and Gerald Guralnik, C. R. Hagen, and Tom Kibble.[19][20][21][22][23][24][25]
1964Sheldon Glashow andJames Bjorken predict the existence of the charm quark. The addition is proposed because it allows for a better description of theweak interaction (the mechanism that allows quarks and other particles to decay), equalizes the number of knownquarks with the number of knownleptons, and implies a mass formula that correctly reproduced the masses of the knownmesons.
1968Stanford University:Deep inelastic scattering experiments at theStanford Linear Accelerator Center (SLAC) show that theproton contains much smaller, point-like objects and is therefore not an elementary particle. Physicists at the time are reluctant to identify these objects withquarks, instead calling thempartons — a term coined by Richard Feynman. The objects that are observed at SLAC will later be identified asup anddown quarks. Nevertheless, "parton" remains in use as a collective term for the constituents ofhadrons (quarks,antiquarks, andgluons). The existence of thestrange quark is indirectly validated by the SLAC's scattering experiments: not only is it a necessary component of Gell-Mann and Zweig's three-quark model, but it provides an explanation for thekaon (K) andpion (π) hadrons discovered in cosmic rays in 1947.
1973Frank Anthony Wilczek discover the quark asymptotic freedom in the theory of strong interactions; receives theLorentz Medal in 2002, and the Nobel Prize in Physics in 2004 for his discovery and his subsequent contributions toquantum chromodynamics.[29]
1974Burton Richter andSamuel Ting: Charm quarks are produced almost simultaneously by two teams in November 1974 (seeNovember Revolution) — one atSLAC under Burton Richter, and one atBrookhaven National Laboratory under Samuel Ting. The charm quarks are observed bound with charmantiquarks inmesons. The two discovering parties independently assign the discovered meson two different symbols, J and ψ; thus, it becomes formally known as theJ/ψ meson. The discovery finally convinces the physics community of the quark model's validity.
1977Leon Lederman observes thebottom quark with his team atFermilab.[30] This discovery is a strong indicator of thetop quark's existence: without the top quark, the bottom quark would be without a partner that is required by the mathematics of the theory.
1982Alain Aspect, J. Dalibard, and G. Roger perform a polarization correlation test ofBell's inequality that rules out conspiratorial polarizer communication
1995 Thetop quark is finally observed by a team atFermilab after an 18-year search.[30] It has a mass much greater than had been previously expected — almost as great as a gold atom.
^Yndurain, Francisco Jose; Quantum Chromodynamics: An Introduction to the Theory of Quarks and Gluons, Springer Verlag, New York, 1983.ISBN0-387-11752-0
^Weinberg, Steven; The Quantum Theory of Fields: Foundations (vol. I), Cambridge University Press (1995)ISBN0-521-55001-7. The first chapter (pp. 1–40) of Weinberg's monumental treatise gives a brief history of Q.F.T., pp. 608.
^Weinberg, Steven; The Quantum Theory of Fields: Modern Applications (vol. II), Cambridge University Press:Cambridge, U.K. (1996)ISBN0-521-55001-7, pp. 489.
^Pais, Abraham; Inward Bound: Of Matter & Forces in the Physical World, Oxford University Press (1986)ISBN0-19-851997-4 Written by a former Einstein assistant at Princeton, this is a beautiful detailed history of modern fundamental physics, from 1895 (discovery of X-rays) to 1983 (discovery of vectors bosons at C.E.R.N.)
