Introductory Address

Abstract

The science of elementary particles has in recent years naturally become the most fundamental of all pursuits in physics. In this lecture, I shall attempt to present a broad and distant view of the current scene in elementary particle physics and indicate to you the general trend of ideas in this field. The most dominant in this trend is the concept of symmetry, which is playing an increasingly fundamental role in the study of interactions of elementary particles. It will be rewarding for us to discuss this in an historical perspective. We shall start with a quotation from Newton’s Opticks:

“All these things being consider’d, it seems probable to me, that God in the Beginning form’d Matter in solid, massy, hard, impenetrable, moveable Particles, of such Sizes and Figures, and with such other Properties, and in such Proportion to Space, as most conducted to the End for which he form’d them; and that these primitive Particles being Solids, are incomparably harder than any porous Bodies compounded of them; even so very hard, as never to wear or break in pieces; no ordinary Power being able to divide what God himself made one in the first Creation. While the Particles continue entire, they may compose Bodies of one and the same Nature and Texture in all Ages: But should they wear away, or break in pieces, the Nature of Things, depending on them, would be changed. Water and Earth, composed of old worn Particles and Fragments of Particles, would not be of the same Nature and Texture now, with Water and Earth composed of entire Particles in the Beginning. And therefore, that Nature may be lasting, the Changes of Corporeal Things are to be placed only in the various Separations and new Associations and Motions of these permanent Particles; compound Bodies being apt to break, not in the midst of solid Particles, but where those Particles are laid together, and only touch in a few Points.”