Symposium on Time and Relativity
Paper Abstracts
Richard T. W. Arthur - Time, Inertia and the Relativity Principle
In this paper I try to sort out a tangle of issues regarding time, inertia, proper time and the so-called "clock hypothesis" raised by Harvey Brown's discussion of them in his recent book, Physical Relativity. I attempt to clarify the connection between time and inertia, as well as the deficiencies in Newton's "derivation" of Corollary 5, by giving a group theoretic treatment deriving from work of J.-P. Provost. This shows how both the Galilei and Lorentz transformations may be derived from the relativity principle on the basis of certain elementary assumptions regarding time. I then reflect on the implications of this for understanding proper time and the clock hypothesis.
Katherine Brading - What's in a theory? Hilbert and the "Harvey Brown pedagogy"
I will pick up on Antigone’s theme of what she calls the “Brown pedagogy”, on how to search for and understand the physical significance of our mathematical theories in physics. One aspect of this pedagogy concerns the role of measurement devices in theories, and specifically rods and clocks in relativity. A second aspect on display in Physical Relativity is the level of detailed investigation into the mathematical and logical structure of a theory that Brown undertakes, in his enquiry into how best to understand both special and general relativity. I focus on this second aspect, and on General Relativity. In this context, I discuss David Hilbert’s applications of his “axiomatic method” in physics, and Emmy Noether’s 1918 theorems, the origins of which lie in Hilbert’s work on generally covariant physical theories. Harvey Brown and I have used Noether’s theorems to examine various features of General Relativity, and I end by applying one of our results to an example found in Chapter 9 of Physical Relativity.
Amit Hagar - Length Matters: The Einstein-Swann Correspondence and the Constructive Approach to Special Relativity
I discuss a rarely mentioned correspondence between Einstein and W.F.G. Swann on the constructive approach to the special theory of relativity, analyzing the consequences of postulating a minimal length scale in the attempts to construct a dynamical explanation of relativistic kinematical effects. I use this analysis to shed light on several issues under dispute in current philosophy of spacetime that were highlighted recently in Harvey Brown's monograph *Physical Relativity*, namely, Einstein's view on the distinction between principle and constructive theories, and the philosophical consequences of pursuing the constructive approach to the special theory of relativity.
Don Howard - Einstein on the Principle Theories/Constructive Theories Distinction
This talk examines the history of Einstein's distinction between principle theories and constructive theories, arguing that it has roots that go back to Newton's dispute with Hooke over the constitution of light, and following the story forward to the way the distinction did important work not only in the genesis of the special theory of relativity but also in Einstein's development of the photon hypothesis and his in his dispute with Weyl over whether and how a theory of everything possesses empirical content. Working from this historical perspective, I will also offer some suggestions for interpreting Einstein's employment of the distinction, with the focus on the respective roles envisioned for principle theories and constructive theories.
Michel Janssen - Drawing the line between kinematics and dynamics in special relativity
I defend the widely held view challenged by Harvey Brown in his recent book that special relativity is preferable to those parts of Lorentz’s electron theory it replaced because various phenomena that special relativity reveals to be of purely kinematical origin were given a dynamical explanation in Lorentz’s theory. The phenomena most commonly discussed in this context in the philosophical literature are length contraction and time dilation. I consider three other such phenomena that played a role in the early reception of special relativity in the physics community: the Fresnel drag effect in the Fizeau experiment, the velocity dependence of electron mass in the beta-ray deflection experiments of Kaufmann and others, and the delicately balanced turning couples on a charged capacitor in the Trouton-Noble experiment. I offer brief historical sketches of how Lorentz’s dynamical explanations of these phenomena were replaced by their now standard kinematical explanations. I then take up the important philosophical challenge posed by Harvey Brown’s work of clarifying how those kinematical explanations are supposed to work.
Antigone Nounou - The Principle/Constructive Theory distinction in Quantum Field Theories
I argue that although the Principle Theory / Constructive Theory distinction may still be drawn in the case of QFTs, it is not a clear-cut dichotomy. However, there is some merit in insisting on this distinction: it allows us to investigate whether two lessons taken from “Brown’s pedagogy” apply. The lessons I am referring to are: (i) principle theories (or the principles of any theory for that matter) do not provide adequate explanations of phenomena by themselves, and (ii) principle theories (or the principles of a theory) tell us nothing about how theoretical/mathematical entities acquire their physical (or operational) significance. What the case of QFTs shows, I claim, is that whereas the first lesson from Brown’s pedagogy does not always pertain, the second is vindicated.
Oliver Pooley - A Glorious Non-Entity... Revisited
According to the still dominant view, certain structures featuring in the standard formulations of our physical theories represent primitive elements of reality: the geometrical structures of space, time and spacetime. The ``dynamical approach'' to special relativity offers the promise of a reductive account of these structures. The guiding intuition is that geometrical structures are reducible to the symmetries of the dynamical laws governing \emph{matter}. This raises two questions: can one make sense of the symmetry of a law independently of the geometrical notions one is hoping to account for and what notion of natural law is presupposed by the account? One approach to answering the first question takes an essentially Humean view of laws, leaving the dynamical approach looking like a more radical version of Huggett's recent version of relationalism.
There is also the question of how the dynamical approach should be pursued in the context of general relativity. In this context, Harvey Brown advocates viewing the metric field as representing a primitive, real field, but one that has to earn its geometrical interpretation. Can this be squared with a reductive attitude to the analogous structures in Newtonian mechanics and special relativity? Does the view really remain distinct from substantivalism?
Robert Rynasiewicz - Simultaneity, Convention, Reference and Dynamics
I show the exact sense in which frame-relative distant simultaneity is conventional. The sense in which it is conventional is non-trivial to the extent that active covariance ("gauge freedom") in general relativity is non-trivial. This "gauge freedom" (and the conventionality of simultaneity) arises fundamentally from the nature of reference. Dynamics enters only to the extent that it is commonplace that objects subject to dynamical laws play a role in the grounding of reference.