Hughes - The theoretical practices of physics: philosophical essays

THE THEORETICAL PRACTICES OF PHYSICS

Philosophical Essays

R. I. G. HUGHES

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R. I. G. Hughes 2010

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Library of Congress Cataloging in Publication Data

Hughes, R.I.G.
The theoretical practices of physics : philosophical essays / R. I. G. Hughes.
p. cm.
Includes bibliographical references and index.
ISBN 9780199546107 (hardback : alk. paper) 1. PhysicsPhilosophy. I. Title.
QC6.2.H84 2009

530.01dc22 2009029698

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Printed in Great Britain
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ISBN 9780199546107
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For Barbara

Our mutual love of theatre brought us together one Spring night in the Autumn of our days, and together we have lived our own drama filled with joy, laughter, and love. Thank you, my Dear, for bringing a new, undreamedof dimension to my life, and for your unfailing love, encouragement, and support. In the words of the Bard:

That time of year thou mayst in me behold
When yellow leaves, or none, or few, do hang
Upon those boughs which shake against the cold,
Bare ruined choirs where late the sweet birds sang.
In me thou seest the twilight of such day
As after sunset fadeth in the west,
Which by and by black night doth take away,
Deaths second self, that seals up all the rest.
In me thou seest the glowing of such fire
That on the ashes of his youth doth lie
As the deathbed whereon it must expire,
Consumed with that which it was nourished by.
This thou perceivst, which makes thy love more strong,
To love that well which thou must leave ere long.

William Shakespeare, Sonnet 73

Over the last ten to twenty years, I have become increasingly interested in exploring the ways in which scientists, and physicists in particular, explain and communicate their theories to each other and to the world at largein other words, the methods they practise in the discourse of physics. As a philosopher of physics, my interest and research in this area led me to the conclusion that I wanted to write a series of essays dealing with various facets of this subject, both philosophical and scientific, and then to tie them together in a book. This book is the result of this quest, and covers a wide range of subjects, from the application of literary criticism to the discussions and analysis of writings in classical and quantum mechanics.

The book consists of eight essays, all within the Philosophy of Physics, and varying in length. They fall into three categories. In the first category are the essays which examine specific branches of physics: Essay 2 covers Bohm and Pines papers on the plasma theory of metals in the early 1950s; Essay 6, Kenneth Wilsons criticalpoint phenomena up to 2000; and Essay 8, the AharonovBohm effect. In the second category are the essays that concentrate on facets of physics that philosophers attend to: laws of physics in Essay 3; disunities in physics in Essay 4; models and representation in Essay 5; and theoretical explanations in Essay 7. In the third category is Essay 1, a hybrid essay built from criticism and the general theory of relativity.

Essay 1 introduces criticism, not as disapproval, but as the definition and judgement of literary or artistic work. The literature discussed is Newtons Principia (Essay 3); Newtons Opticks (Essay 7); Einsteins papers on The Brownian Motion (Essay 4); and Einsteins The Perihelion Motion of Mercury by the General Theory of Relativity (Essay 1). Essay 2 introduces theoretical practice. It provides a commentary on Bohm and Pines quartet, A Collective Description of Electron Interaction. In the quartet, Bohm and Pines employ (a) two theories: classical mechanics and quantum mechanics; (b) sundry models; (c) several modes of description; and (d) various approximative strategies. By treating these publications as texts, it casts the philosopher of science in the role of literary critic.

When tied together, the eight essays form the whole, a discussion of the theoretical practices of physics.

For the human being in his surrounding world there are many kinds of praxis, and among them is this peculiar and historically late one, theoretical praxis.

Edmund Husserl

Alfred Tarskis Introduction to Logic and to the Methodology of Deductive Sciences opens with this assertion: Every scientific theory is a system of sentences which are accepted as true and which may be called laws or asserted statements or, for short, simply statements (1965: 3).

The statement view of theories, as we may call it, was shared by the logical empiricists, and went almost unchallenged in the philosophy of science during the middle decades of this century. If, as Tarski does in the case of mathematics, we add the requirement that the statements of a theory are to be laid out as a formal deductive system, we get the following thesis:

The sciences are properly expounded in formal axiomatized systems. The sciences are to be axiomatized: that is to say, the body of truth that each defines is to be exhibited as a sequence of theorems inferred from a few basic postulates or axioms. And the axiomatization is to be formalized: that is to say, its sentences are to be formulated within a well-defined language, and its arguments are to proceed according to a precisely and explicitly set of logical rules. (Barnes 1975: xi)