The urge and the interest to find those ultimate elements in terms of which everything else is made of are almost as old as the human civilization. However, as our knowledge increases what were thought to be elementary may turn out to be composites. Consequently, the class of these supposedly fundamental elements changes with time. Such was, for example, the periodic table of atoms in the last century. Today we know that all different molecules, atoms, and nuclei are complexes resulting from the existence and the interactions of some thirty particles which are called “elementary particles”.
REFERENCES
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An interesting and personal account of this discovery was given by Thomson in his book Recollections and Reflections (G. Bell and Sons, Ltd., 1936).
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For a detailed discussion of these experiments see, e.g., C. S. Wu, The Neutrino, Memorial Volume to Wolfgang Pauli (Pergamon Press, 1960)
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The possibility of a two‐component relativistic theory of a spin particle was first discussed by
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Laotse, Tao Té Chin, p. 1 (about 550 B. C.).
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