Constructing Reality: Quantum Theory and Particle Physics
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Questions of the fundamental nature of matter continue to inspire and engage our imagination. However, the exciting new concepts of strings, supersymmetry and exotic matter build on ideas that are well known to physicists but mysterious and puzzling to people outside of these research fields. Covering key conceptual developments from the last century, this book provides a background to the bold ideas and challenges faced by physicists today. Quantum theory and the Standard Model of particles are explained with minimal mathematics, and advanced topics, such as gauge theory and quantum field theory, are put into context. With concise, lucid explanations, this book is an essential guide to the world of particle physics.
condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom: for such an intellect nothing could be uncertain; and the future just like the past would be present before its eyes” (Laplace, 1814). Quoted in Kline (1980, p. 67). 12. The calculus. The calculus was invented more or less simultaneously by Newton and by Gottfried Wilhelm Leibniz (1646–1716), and it is Leibniz’s notation that we use today. Integral calculus ﬁnds the area under a given
measure of its energy-content; if the energy changes by ε, the mass changes in the same sense by ε ÷ 9×1020, the energy being measured in ergs, and the mass in grammes. It is not impossible that with bodies whose energycontent is variable to a high degree (e.g. with radium salts) the theory may be successfully put to the test” (Einstein, 1905b). Einstein used L in place of ε. The test could not be performed without considerably more knowledge of the structure of nuclei. For details, see Pais
the end of the nineteenth century did scientists seriously encounter the world of the small. No one had thought much about the limitations on observation imposed by the ﬁnite impact of the particles required for sensation. For one thing, you could always imagine a god who could see with a delicacy beneath the reach of mortals, and you could strive to discover the laws as the god would perceive them. For another, no one had yet needed to invoke any physical system small enough to be disturbed by
of a phenomenon, a demand that remains embedded in our culture because it is important in human affairs. We tend to explain human action in terms of motive and objective, but these terms are absent from modern science. In the generation prior to Newton, Johannes Kepler (1571–1630) hypothesized a force on the planets to keep them moving around the Sun, and felt the need to postulate a “soul” that caused it.9 Newton did not care to explain gravity. He simply described its effect. 6 constructing
these theories are still visions upon the horizon of the great sea of ignorance, and not yet ﬁrmly linked to the connected islands of the Standard Model, which today accounts for nearly all the known fundamental phenomena of the physical world.19 Here is the point: Surprisingly, the renormalization program cannot be made to work for most equations of motion. It does not work, for example, for Fermi’s theory of beta decay described above. It does work when the force equations are introduced via