600 BCEKanada theorizes the existence of four kinds of atoms, which could combine to produce diatomic and triatomic molecules.
430 BCEDemocritus speculates about fundamental indivisible particles--calls them "atoms"
200 BCEJainism calls atom Paramanu which can neither be created nor destroyed. It is eternal, i.e., it existed in the past, exists in the present and will continue to exist in the future. It is the permanent basis of the physical existence. The entire physical existence is composed of these ultimate atoms.
^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.
^ abWeinberg, 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.)