In a recent article Humphreys has developed an intriguing proposal for making sense of emergence. The crucial notion for this purpose is what he calls "fusion" and his paradigm for it is quantum nonseparability. In what follows, we will develop this position in more detail, and then discuss its ramifications and limitations. Its ramifications are quite radical; its limitations are substantial. An alternative approach to emergence that involves quantum physics is then proposed.
This paper involves one crucial assumption; namely, that the statistical predictions of quantum mechanics for Bell's variant of the EPR experiment will continue to be verified as detector efficiencies are improved and the need for coincidence counters is eliminated. This assumption entails that any hidden-variables theory for quantum mechanics must violate Bell's inequality--the inequality derived in Bell (1964). It is shown here that four locality conditions are involved in the derivation of Bell's inequality; and that a violation of any of (...) the four locality conditions will either entail the existence of superluminal influences or the existence of superluminal signals (superluminal influences that can be used to transmit information), if conspiratorial theories can be ruled out. The attempts so far to rule out conspiratorial theories are all found to be rather dubious, but there are other considerations developed here that rule them out convincingly. Finally, it is demonstrated that violations of each of the four locality conditions can be used to transmit information superluminally, if certain auxiliary conditions are satisfied. This is of particular interest because one of these conditions corresponds to a condition dubbed "completeness" by Jon Jarrett. Jarrett and others have suggested that violations of completeness cannot be used to send information superluminally. Demonstrating otherwise is, perhaps, the most significant result obtained in this paper. (shrink)
Conventional wisdom has it that chaotic behavior is either strongly suppressed or absent in quantum models. Indeed, some researchers have concluded that these considerations serve to undermine the correspondence principle, thereby raising serious doubts about the adequacy of quantum mechanics. Thus, the quantum chaos question is a prime subject for philosophical analysis. The most significant reasons given for the absence or suppression of chaotic behavior in quantum models are the linearity of Schrödinger’s equation and the unitarity of the time-evolution described (...) by that equation. Both are shown in this essay to be irrelevant by demonstrating that the crucial feature for chaos is the nonseparability of the Hamiltonian. That demonstration indicates that quantum chaos is likely to be exhibited in models of open quantum systems. A measure for probing such models for chaotic behavior is developed, and then used to show that quantum mechanics has chaotic models for systems having a continuous energy spectrum. The prospects of this result for vindicating the correspondence principle (or the motivation behind it, at least) are then briefly examined. (shrink)
Recently, Rueger and Sharp and Koperski have been concerned to show that certain procedural accounts of model confirmation are compromised by non-linear dynamics. We suggest that the issues raised are better approached by considering whether chaotic data analysis methods allow for reliable inference from data. We provide a framework and an example of this approach.
Two notions of evidence are focused on in this essay, Carnap's positive-relevance notion of evidence (1962, pp. 462 ff.), and Achinstein's notion of potential evidence (1978; and 1983, pp. 322–350). Achinstein creates several interesting examples in his attempt to find faults in Carnap's notion of evidence; his motive, ultimately, is to impel us towards potential evidence. The purpose of this essay is to show that positive relevance is significantly more promising than potential evidence with respect to capturing the scientific sense (...) of the term evidence. This is accomplished by finding faults in the notion of potential evidence, and by defending positive relevance against Achinstein's examples. (shrink)
This paper is a critical discussion of a recent article by Bas van Fraassen in which he suggests the following view: we should admit that we have no explanation of the EPR correlations, but refuse to consider the correlations as mysterious nevertheless. We shall focus on just three of the claims made by van Fraassen in support of this view. The three claims are these:The EPR correlations cannot be explained by signals being transmitted from one component of an EPR compound (...) to the other.There is, in the EPR situation, no empirically verifiable action at a distance.The demand for an explanation of the EPR correlations is similar to the Aristotelian demand of the post-Newtonian proponents of the law of inertia to explain what keeps a body moving if there are no forces impressed on it. (shrink)
I defend the projection postulate against two of Margenau's criticisms. One involves two types of nonideal measurements, measurements that disturb and measurements that annihilate. Such measurements cannot be characterized using the original version of the projection postulate. This is one of the most interesting and powerful objections to the projection postulate since most realistic measurements are nonideal, in Margenau's sense. I show that a straightforward generalization of the projection postulate is capable of handling the more realistic kinds of measurements considered (...) by Margenau. His other objection involves the EPR (Einstein-Podolsky-Rosen) situation. He suggests that there is a significant potential for violations of the no-superluminalsignals requirement of the special theory of relativity, if projections occur in this situation and others like it. He also suggests that what is paradoxical about this situation disappears if the projection postulate is rejected. I show that it is not possible to use measurements on pairs of spatially-separated systems whose states are entangled to transmit information superluminally, and generalize this result to include nonideal measurements. I also show that EPR's dilemma does not really depend on the projection postulate. (shrink)
The standard mathematical formulation of quantum mechanics is specified. Bohm's ontological interpretation of quantum mechanics is then shown to be incapable of providing a suitable interpretation of that formulation. It is also shown that Bohm's interpretation may well be viable for two alternative mathematical formulations of quantum mechanics, meaning that the negative result is a significant though not a devastating criticism of Bohm's interpretation. A preliminary case is made for preferring one alternative formulation over the other.
The purpose of this paper is to solve a serious problem for the projection postulate involving the time-energy uncertainty relation. The problem was recently raised by Teller, who believes that the problem is insoluble and, consequently, that the projection postulate should no longer be regarded as a serious focus for interpretive investigation.
Jarrett has demonstrated that "strong locality," one of the conditions used by Bell to derive his well known inequality, is equivalent to the conjunction of two other conditions which he calls "hidden locality" and "completeness." He has also demonstrated that if it is possible to control the hidden states of the measured system, then violations of hidden locality can be used to transmit information superluminally; and that this is not so with respect to violations of completeness. This he has taken (...) to mean that it is not possible to use violations of completeness to do so under any circumstances. In this essay, it is argued that such violations can be used to do so, if one other condition is satisfied. (shrink)
Bell (1964) demonstrated that if two restrictions are imposed on the hypothetical hidden variables supposed to underlie quantum mechanical states, then it is possible to derive an inequality that is violated by certain predictions of QM (Quantum Mechanics); the predictions concern pairs of systems whose states are strongly correlated. The two restrictions are denoted herein as SL (Strong Locality) and HA (Hidden Autonomy)1, and the inequality as BI (the Bell Inequality). Since SL and HA together entail BI, and QM violates (...) BI, it follows that any HVT (Hidden-Variables Theory) for QM must violate either SL or HA.It is well known that a condition known as PA (Perfect Anti-correlation) was also used by Bell to derive the inequality. PA says that parallel experiments (experiments with parallel spin-analyzer orientations) never yield the same results. (shrink)
This is a sophisticated, nontechnical introduction to the main issues in the philosophy of physics. It is exceptionally well-written. The issues are well-chosen, the prose are clear and concise, the text is organized into manageable sections arranged in a logical manner, and the treatment of various positions on the main issues is evenhanded. Also, each of the three central chapters is supplemented by an annotated bibliography that will serve well as a selective guide for motivated readers.
In a previous essay I argued that quantum chaos cannot be exhibited in models of quantum systems within von Neumann's mathematical framework for quantum mechanics, and that it can be exhibited in models within Dirac's formal framework. In this essay, the negative thesis concerning von Neumann's framework is elaborated further by extending it to the case of Hamiltonian operators having a continuous spectrum. The positive thesis concerning Dirac's formal framework is also elaborated further by constructing a chaotic model of an (...) open quantum system in which an entropy measure is shown to approach its maximum value as time goes to infinity. Having such an entropy measure is a characteristic that is closely connected to chaotic behavior in phase space models of classical systems. (shrink)