We present a precise form of structural realism, called group structural realism , which identifies ‘structure’ in quantum theory with symmetry groups. However, working out the details of this view actually illuminates a major problem for structural realism; namely, a structure can itself have structure. This article argues that, once a precise characterization of structure is given, the ‘metaphysical hierarchy’ on which group structural realism rests is overly extravagant and ultimately unmotivated.
I propose a general geometric framework in which to discuss the existence of time observables. This framework allows one to describe a local sense in which time observables always exist, and a global sense in which they can sometimes exist subject to a restriction on the vector fields that they generate. Pauli׳s prohibition on quantum time observables is derived as a corollary to this result. I will then discuss how time observables can be regained in modest extensions of quantum theory (...) beyond its standard formulation. (shrink)
Ashtekar has illustrated that two of the available roads to testing for time asymmetry can be generalized beyond the structure of quantum theory, to much more general formulations of mechanics. The purpose of this note is to show that a third road to T-violation, which I have called "Wigner's Principle," can be generalized in this way as well.
This paper introduces a little-known episode in the history of physics, in which a mathematical proof by Pierre Fermat vindicated Galileo’s characterization of freefall. The first part of the paper reviews the historical context leading up to Fermat’s proof. The second part illustrates how a physical and a mathematical insight enabled Fermat’s result, and that a simple modification would satisfy any of Fermat’s critics. The result is an illustration of how a purely theoretical argument can settle an apparently empirical debate.
This paper is a tour of how the laws of nature can distinguish between the past and the future, or be T-violating. I argue that, in terms of the basic argumentative structure, there are basically just three approaches currently being explored. The first is an application of Curie's Principle, together with the CPT theorem. The second route makes use of a principle due to Pasha Kabir which allows for a direct detection. The third route makes use of a Non-degeneracy Principle, (...) and is related to the energy spectrum of elementary particles. I show how each provides a general template for detecting T-violation, illustrate each with an example, and discuss their prospects in extensions of particle physics beyond the standard model. (shrink)
This note argues that quantum observables can include not just self-adjoint operators, but any member of the class of normal operators, including those with non-real eigenvalues. Concrete experiments, statistics, and symmetries are all expressed in this more general context. However, this more general class of observables also introduces a new restriction on which sets of operators can be interpreted as observables at once. These sets are referred to here as 'sharp sets.
Rovelli argues that the there is disharmony with respect to the arrow of time from the perspective of testable predictions, as compared to the perspective of Schroedinger evolution, and uses this claim as evidence against realist interpretations of the wave function. I argue on the contrary that this disharmony arises only out of a non-standard definition of time reversal that ignores the 'big-T', and that harmony is restored when the standard definition is adopted.
This dissertation is about the sense in which the laws of quantum theory distinguish between the past and the future. I begin with an account of what it means for quantum theory to make such a distinction, by providing a novel derivation of the meaning of "time reversal." I then show that if Galilei invariant quantum theory does distinguish a preferred direction in time, then this has consequences for the ontology of the theory. In particular, it requires matter to admit (...) "internal" degrees of freedom, in that the position observable generates a maximal abelian algebra. I proceed to show that this is not a purely quantum phenomenon, but can be expressed in classical mechanics as well. I then illustrate three routes for generating quantum systems that distinguish a preferred temporal direction in this way. (shrink)
Wigner gave a well-known proof of Kramers degeneracy, for time reversal invariant systems containing an odd number of half-integer spin particles. But Wigner's proof relies on the assumption that the Hamiltonian has an eigenvector, and thus does not apply to many quantum systems of physical interest. This note illustrates an algebraic way to talk about Kramers degeneracy that does not appeal to eigenvectors, and provides a derivation of Kramers degeneracy in this more general context.
This article deals with the question of what time reversal means. It begins with a presentation of the standard account of time reversal, with plenty of examples, followed by a popular non-standard account. I argue that, in spite of recent commentary to the contrary, the standard approach to the meaning of time reversal is the only one that is philosophically and physically viable. The article concludes with a few open research problems about time reversal.
Many have suggested that the transformation standardly referred to as `time reversal' in quantum theory is not deserving of the name. I argue on the contrary that the standard definition is perfectly appropriate, and is indeed forced by basic considerations about the nature of time in the quantum formalism.
Galileo's refutation of the speed-distance law of fall in his Two New Sciences is routinely dismissed as a moment of confused argumentation. We urge that Galileo's argument correctly identified why the speed-distance law is untenable, failing only in its very last step. Using an ingenious combination of scaling and self-similarity arguments, Galileo found correctly that bodies, falling from rest according to this law, fall all distances in equal times. What he failed to recognize in the last step is that this (...) time is infinite, the result of an exponential dependence of distance on time. Instead, Galileo conflated it with the other motion that satisfies this ‘equal time’ property, instantaneous motion. (shrink)
How should we characterise the observable aspects of quantum theory? This paper argues that philosophers and physicists should jettison a standard dogma: that observables must be represented by self-adjoint or Hermitian operators. Four classes of non-standard observables are identified: normal operators, symmetric operators, real-spectrum operators, and none of these. The philosophical and physical implications of each are explored.
Jim Weatherall has suggested that Einstein's hole argument, as presented by Earman and Norton, is based on a misleading use of mathematics. I argue on the contrary that Weatherall demands an implausible restriction on how mathematics is used. The hole argument, on the other hand, is in no new danger at all.
We explore the facts and fiction regarding Curie's own example of Curie's principle. Curie's claim is vindicated in his suggested example of the electrostatics of central fields, but fails in many others. Nevertheless, the failure of Curie's claim is still of special empirical interest, in that it can be seen to underpin the experimental discovery of parity violation and of CP violation in the 20th century.
This paper states and proves a precise sense in which, if all the measurable properties of an ordinary quantum mechanical system are ultimately derivable from position, then time in quantum mechanics can have no preferred direction. In particular, I show that when the position observable forms a complete set of commuting observables, Galilei invariant quantum mechanics is guaranteed to be time reversal invariant.
I point out that some common folk wisdom about time reversal invariance in classical mechanics is strictly incorrect, by showing some explicit examples in which classical time reversal invariance fails, even among conservative systems. I then show that there is nevertheless a broad class of familiar classical systems that are time reversal invariant.
Two fundamental business ethics issues that repeatedly surface in the academic literature relate to business's role in the development of public policy [Suarez, S. L.: 2000, Does Business Learn? (The University of Michigan Press, Ann Arbor, MI); Roberts, R. W. and D. D. Bobek: 2004, Accounting, Organizations and Society 29(5-6), 565-590] and its role in responsibly managing the natural environment [Newton, L.: 2005, Business Ethics and the Natural Environment (Blackwell Publishing, Oxford)]. When studied together, researchers often examine if, and (...) how, corporations influence environmental policy decisions. Drawing from literatures on corporate political activity, corporate social and environmental performance, and corporate environmental disclosure, we develop and empirically examine two research questions concerning the relations between corporate political expenditures, environmental performance, and environmental disclosure. The questions are: (1) Do corporations that are poorer environmental performers spend more on political activities than their better-performing counterparts? (2) Is there an association between corporations' spending on political activities and the extent of their financial report environmental disclosures? We investigated these questions through analyses of data we gathered on a sample consisting of 119 U.S. environmentally sensitive firms for the 2001-2002 election cycle. After controlling for firm size and specific industry effects, our tests reveal a significant, inverse relationship between firm environmental performance and political spending. This is consistent with the notion that U.S. firms with relatively poorer environmental performance records engage more intensely in corporate political activities as part of their overall strategic management of their relationship with the state. In addition, a significant and positive association between the amount of political spending and the extent of environmental disclosure suggests that environmental disclosure and political spending are both proactive, complementary tactics to strategically manage public policy pressure. If corporations' strategies are intentionally designed to unreasonably limit their environmental responsibilities or to misrepresent firm environmental performance, then we argue that these activities reflect a significant lapse in ethical conduct. (shrink)
Since the publication of Edmund Gettier's challenge to the traditional epistemological doctrine of knowledge as justified true belief, Roberts and Wood claim that epistemologists lapsed into despondency and are currently open to novel approaches. One such approach is virtue epistemology, which can be divided into virtues as proper functions or epistemic character traits. The authors propose a notion of regulative epistemology, as opposed to a strict analytic epistemology, based on intellectual virtues that function not as rules or even as (...) skills but as habits of the heart. To that end, they divide the task of clarifying and expounding their notion in the book's two parts.In the first part, Roberts and Wood examine various components that constitute their notion of regulative epistemology. The first are the epistemic goods or goals that drive the epistemic process. What is needed, claim Roberts and Wood, is an enriched notion of these goods rather than the restricted notion of justified true belief. Epistemic agents are more than calculating devices in that …. (shrink)
What is the opposite of freedom? In _Freedom as Marronage_, Neil Roberts answers this question with definitive force: slavery, and from there he unveils powerful new insights on the human condition as it has been understood between these poles. Crucial to his investigation is the concept of marronage—a form of slave escape that was an important aspect of Caribbean and Latin American slave systems. Examining this overlooked phenomenon—one of action from slavery and toward freedom—he deepens our understanding of freedom (...) itself and the origin of our political ideals. Roberts examines the liminal and transitional space of slave escape in order to develop a theory of freedom as marronage, which contends that freedom is fundamentally located within this space—that it is a form of perpetual flight. He engages a stunning variety of writers, including Hannah Arendt, W. E. B. Du Bois, Angela Davis, Frederick Douglass, Samuel Taylor Coleridge, and the Rastafari, among others, to develop a compelling lens through which to interpret the quandaries of slavery, freedom, and politics that still confront us today. The result is a sophisticated, interdisciplinary work that unsettles the ways we think about freedom by always casting it in the light of its critical opposite. (shrink)
This study examines the relation between firms' corporate philanthropic giving and their performance in three other social domains - employee relations, environmental issues, and product safety. Based on a sample of 384 U.S. companies and using data pooled from 1998 through 2000, we find that worse performers in the other social areas are both more likely to make charitable contributions and that the extent of their giving is larger than for better performers. Analyses of each separate area of social performance, (...) however, indicate that the relation between giving and negative social performance only holds for the environmental issues and product safety areas. We find no significant association between corporate philanthropy and employee relations concerns. In general, these findings suggest that corporate philanthropy may be more a tool of legitimization than a measure of corporate social responsibility. (shrink)