It has been argued, partly from the lack of any widely accepted solution to the measurement problem, and partly from recent results from quantum information theory, that measurement in quantum theory is best treated as a black box. However, there is a crucial difference between ‘having no account of measurement' and ‘having no solution to the measurement problem'. We know a lot about measurements. Taking into account this knowledge sheds light on quantum theory as a theory of information and computation. (...) In particular, the scheme of ‘one-way quantnum computation' takes on a new character in light of the role that reference frames play in actually carrying out any one-way quantum comptuation. ‡Thanks to audiences at the PSA and the Centre for Time, University of Sydney, for helpful comments and questions. †To contact the author, please write to: Department of Philosophy, University of South Carolina, Columbia, SC 29208; e-mail: firstname.lastname@example.org. (shrink)
This essay is a discussion of the philosophical and foundational issues that arise in non-relativistic quantum theory. After introducing the formalism of the theory, I consider: characterizations of the quantum formalism, empirical content, uncertainty, the measurement problem, and non-locality. In each case, the main point is to give the reader some introductory understanding of some of the major issues and recent ideas.
Taking a cue from Bohr’s use of the notion of a reference frame in his reply to EPR’s argument against the completeness (and consistency) of standard quantum theory, this paper presents an analysis ofthe role of reference frames in the situation considered by EPR, using a quantum‐theoretical account of physical reference frames based on the work of Mackey, and Aharonov and Kaufherr. That analysis appears to justify at least some crucial aspects of a Bohrian reply to EPR.
Is the quantum-logic interpretation dead? Its near total absence from current discussions about the interpretation of quantum theory suggests so. While mathematical work on quantum logic continues largely unabated, interest in the quantum-logic interpretation seems to be almost nil, at least in Anglo-American philosophy of physics. This paper has the immodest purpose of changing that fact. I shall argue that while the quantum-logic interpretation faces challenges, it remains a live option. The usual objections either miss the mark, or admit a (...) reasonable answer, or fail to decide the issue conclusively. (shrink)
An outstanding problem in so-called modal interpretations of quantum mechanics has been the specification of a dynamics for the properties introduced in such interpretations. We develop a general framework (in the context of the theory of stochastic processes) for specifying a dynamics for interpretations in this class, focusing on the modal interpretation by Vermaas and Dieks. This framework admits many empirically equivalent dynamics. We give some examples, and discuss some of the properties of one of them. This approach is applicable (...) to a wider class of theories, in particular, those using (discrete) strict effective—as in decoherence theory—superselection rules. (shrink)
If observation is 'theory-laden', how can there be 'observationally equivalent theories'? How can the observations 'laden' by one theory be 'the same as' those 'laden' by another? The answer might lie in the expressibility of observationally equivalent theories in a common mathematical formalism.
This paper proposes a logic, motivated by modal interpretations, in which every quantum mechanics propositions has a truth-value. This logic is completely classical, hence violates the conditions of the Kochen-Specker theorem. It is shown how the violation occurs, and it is argued that this violation is a natural and acceptable consequence of modal interpretations. It is shown that despite its classicality, the proposed logic is empirically indistinguishable from quantum logic.
Quantum mechanics has sometimes been taken to be an empiricist (vs. realist) theory. I state the empiricist's argument, then outline a recently noticed type of measurement--protective measurement--that affords a good reply for the realist. This paper is a reply to scientific empiricism (about quantum mechanics), but is neither a refutation of that position, nor an argument in favor of scientific realism. Rather, my aim is to place realism and empiricism on an even score in regards to quantum theory.
I introduce and review the most recent and most promising model of state vector reduction, that of Ghirardi, Rimini, Weber, and Pearle. This model requires the specification of a reduction basis. At least two questions therefore arise: Are there physical reasons to choose one basis rather than another? Does the choice made lead to any undesirable consequences? I argue that there arephysical reasons to choose from a certain class of reduction bases (a class which includes the choice made by the (...) authors mentioned above), and that such a choice does not lead to problems, contra an argument by Albert and Vaidman. (shrink)
The conceptual structure of orthodox quantum mechanics has not provided a fully satisfactory and coherent description of natural phenomena. With particular attention to the measurement problem, we review and investigate two unorthodox formulations. First, there is the model advanced by GRWP, a stochastic modification of the standard Schrödinger dynamics admitting statevector reduction as a real physical process. Second, there is the ontological interpretation of Bohm, a causal reformulation of the usual theory admitting no collapse of the statevector. Within these two (...) seemingly quite different approaches, we discuss in a comparative manner, several points: The meaning of the state vector, the status of quantum probability, the legitimacy of attributing macro objective properties to physical systems, and the possibility of retrieving the classical limit. Finally, we consider aspects of non-locality and relevant difficulties with formulating a relativistic generalization of the two approaches. (shrink)
I review the modal interpretation of quantum mechanics, some versions of which rely on the biorthonormal decomposition of a statevector to determine which properties are physically possessed. Some have suggested that these versions fail in the case of inaccurate measurements, i.e., when one takes tails of the wavefunction into account. I show that these versions of the modal interpretation are satisfactory in such cases. I further suggest that a more general result is possible, namely, that these versions of the modal (...) interpretation never encounter the sort of trouble that has been claimed to arise in the case of inaccurate measurement. (shrink)