First attempt at a basic introduction to the subject for the research proposal:
Statement Of Topic
Quantum Mechanics is an extremely successful branch of science. It has enabled us to explain the structures of atoms and the details of atomic spectra, radioactivity, and chemical bonding. Elaborations of the fundamental theory has led to satisfactory explanations of nuclear structures and relations, the electrical and thermal properties of solids, superconductivity, the creation and annihilation of elementary particles, the production of anti-matter, Bose-Einstein condensation, the stability of white dwarfs, and neutron stars, and much else. It has also made possible major practical developments such as the electron microscope, the laser, the transistor. Exceedingly delicate experiments have confirmed subtle quantum effects to an astonishing degree of accuracy. It has never been shown to contradict the results of 50 years of experimentation.
If all that is asked from a scientific theory is that it should correctly predict the results of experiments, quantum mechanics works perfectly, and, to paraphrase John Bell, "ordinary quantum mechanics (as far as we know) is just fine for all practical purposes (FAPP)".
However, the basic conceptual foundations of quantum mechanics, when closely examined, can lead, depending on their interpretation, to some puzzling paradoxes and strange, counterintuitive, and to some commentators, unacceptable features. For these reasons, the problem of the interpretation of Quantum Mechanics has produced some very lively debates, and continues to do so. The importance of the interpretation of Quantum Mechanics for the realism-antirealism can hardly be overstressed.
One major point of contention is the way quantum mechanical states are represented within the theory and the conclusions that are to be drawn from such a representation. Quantum Mechanics has the peculiar property that it only assigns probabilities that a physical state will be found at a specific state upon measurement; contrary to a classical theory which could, at least in principle, provide us with definite values for the various properties of the system in question. From a realist point of view, the conclusion to be drawn is that Quantum Mechanics does not provide us with a complete description of the physical system under investigation, something which could, arguably, be achieved through a Hidden Variables theory.
The significance of Bell's Theorem on the possibility of reproducing all of the predictions of quantum mechanics through a (local) hidden variables theory is well known. Bell test experiments to date overwhelmingly show that Bell inequalities are violated. These results provide empirical evidence against local hidden variable theories.
Furthermore, realistic interpretations of quantum mechanics seem to rely, either explicitly or implicitly, on the principles of
Value Definiteness and
Non Contextuality .
Value Definiteness: All observables defined for a QM system have definite values at all times.
Non Contextuality: If a QM system possesses a property (value of an observable), then it does so independently of any measurement context, i.e. independently of how that value is eventually measured.
At first glance, these two principles might even appear to form a "null" hypothesis for any realistic approach, especially if we are trying to extend our classical intuitions into the quantum domain. Both Value Realism and Non-COntextuality incorporate the basic idea of an independence of physical reality from its being measured. Or in other words, we can view this as a form of Cartesian Dualism and a separating of the mental world from the physical one.
Qauntum Mechanics however challenges in a serious way these basic notions through the Kochen-Specker (KS) theorem. The KS theorem establishes a contradiction between VD and NC. Implying that if we are to accept quantum mechanics, and the experimental results do force us into that direction, we have to renounce either VD or NC. As can be readily appreciated, for the realist, it is unclear how a plausible realist interpretation of QM can be achieved that renounced VD but not NC, or vice versa.
All the above problems seem to reinforce Arthur Fine's pronouncement that “realism is dead”. However, these problems should not deter the realist. After the same man that pronounced the death of realism has also mentioned that realism is a powerful tool in the development of science, and therefore it is not advisable that we abandon it. On the other hand if the realist to meet the challenges level at him from the latest scientific developments, and from quantum mechanics more specifically, he needs to undertake a critical re-evaluation of some of the notions that had hitherto formed the basis, at a foundational level, of any realistic interpretation of any physical theory.
In order to achieve this we need to examine some the notions that have been viewed as principle conditions of our conception of the world, including those that we have already mentioned (Value Definiteness, Non-contextuality) but also notions like separability. In addition, we need to go further back and examine critically what is the function of the various theories of truth, within the context of scientific research and discourse, be it correspondence theories of truth of a Tarskian type or minimalistic theories of truth (e.g. Pascal Engel).
What we are aiming at showing, is that there is a way the realist can meet the challenges that quantum mechanics presents. However, in order to achieve this, the realist will need to incorporate into his conception of the natural world the results of quantum mechanics, or to put it differently, to allow his world view to be instructed by the results of quantum mechanics. An integral part of this effort will be focused in evaluating the possible solutions in escaping the consequences of the Kochen-Specker theorem. In summary, some the of available solutions are:
• Denial of Value Definiteness
• Denial of Non-Contextuality, in the form of either a Casual or an Ontological Contextuality
Although most realistic approaches to the interpretation quantum mechanics are directed at showing that quantum theory is incomplete, by pointing out some its bizarre consequences that run counter to some of our fundamental intuitions about the nature of reality, there is an alternative path that is worth exploring. Taking the traditional approach and turning it on its head, we accept the results of quantum mechanics and use them to instruct our world view.
However, such debates can often leave the reader with a sense of frustration. Such views have been expressed by prominent commentators such as Arthur Fine, when he declared realism as dead and went on produce a colourful portayal of realism when he said that all they seek to add is "A desk-thumping, foot stamping shout of "REALLY"!!".
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http://www.drury.edu/ess/philsci/AFine.html
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Comments such as these, however, may not need be taken as signaling the end realism as such.
