In order to stop hijacking https://www.physicsforums.com/showthread.php?t=361216", I'll restart a discussion here about the role of background assumptions and the conceptual aspects of scientific theories, in particular how the "measurement problem" fits in with quantum mechanics and its interpretations. Rather than respond to posts out of context, let me start over with some background.(adsbygoogle = window.adsbygoogle || []).push({});

Wikipedia gives the following introduction to http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics" [Broken]:Using Wikipedia's definition of an interpretation, we can consider it to be the conceptual framework that ties together the math of a theory and the relevant observations taken. It tells you what the physical meanings of your mathematical variables are. According to the Duhem-Quine thesis, it is a requirement of all testable scientific theories that they have an interpretation - a conceptual framework of auxiliary assumptions (Philosophy_of_science#Test_of_an_isolated_theory_impossible). An interpretation of quantum mechanics is a statement which attempts to explain how quantum mechanics informs our understanding of nature. Although quantum mechanics has received thorough experimental testing, many of these experiments are open to different interpretations. ...

Although today this question is of special interest to philosophers of physics, many physicists continue to show a strong interest in the subject. Physicists usually consider an interpretation of quantum mechanics as an interpretation of the mathematical formalism of quantum mechanics, specifying the physical meaning of the mathematical entities of the theory.

This is relevant to quantum mechanics in that a) we need an interpretation, and b) any part of the theory besides the pure math belongs to the interpretation. The experiments, of course, also are not part of the interpretation, but they can only be viewed through an interpretation.

As the lens through which one assigns basic ontological meaning to experiments, one's interpretation of QM is also his http://en.wikipedia.org/wiki/Paradigm#Scientific_paradigm").

If we can agree on the above, then I will make some claims for discussion. First, I claim that all work done in nonrelativistic quantum mechanics since Heisenberg and Schrodinger has been to either to verify or reformulate their math, or to shed light on interpretations. This would mean that Bohm, for example, came up with an interpretation, and not a new theory, using the language of philosophy of science defined above (this is also supported by Bohm calling his own work an interpretation). Am I getting the terminology wrong here? This is more of a question of semantics than a meaningful claim, but it's needed for further discussion.

Let's also take a look at http://en.wikipedia.org/wiki/Measurement_problem" [Broken]:Looking back at the definition of an interpretation, its role is to give physical meaning to the mathematical variables. It must determine which physical things match with which variables. According to the above version of the measurement problem, there exists, in wavefunction-collapse interpretations, a phenomenon (the "something") which we are unable to assign a physical significance to. This leads to my other thesis that any interpretation leading to the measurement problem is either incomplete and in need of further exposition or is not self-consistent and is therefore wrong. The measurement problem in quantum mechanics is the unresolved problem of how (or if) wavefunction collapse occurs. The inability to observe this process directly has given rise to different interpretations of quantum mechanics, and poses a key set of questions that each interpretation must answer. The wavefunction in quantum mechanics evolves according to the Schrödinger equation into a linear superposition of different states, but actual measurements always find the physical system in a definite state. Any future evolution is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the process under examination. Whatever that "something" may be does not appear to be explained by the basic theory.

Further evidence of this is that the measurement problem is not a function of QM itself, but of certain interpretations. The explanation of the problem above limits its scope to collapse interpretations. There are certainly also interpretations that claim to avoid any measurement problem. In http://plato.stanford.edu/entries/qm-bohm/" [Broken] the following:Am I wrong that the measurement problem is a non-issue for QM as a whole? Is there some compelling reason I've missed to go with an interpretation that leads to the measurement problem? Does the measurement problem actually apply to more than just explicit collapse interpretations? Did the measurement problem just arise out of a misunderstanding of Bohr? Hence, those physicists who accuse this interpretation of operating with a mysterious collapse of the wave function during measurements haven't got it right. Bohr accepted the Born statistical interpretation because he believed that the ψ-function has only a symbolic meaning and does not represent anything real. It makes sense to talk about a collapse of the wave function only if, as Bohr put it, the ψ-function can be given a pictorial representation, something he strongly denied.

Please support your reply with literature or argument from literature as I have made an attempt to do. Let me know what I've gotten wrong or what needs more support or clarification.

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# QM Interpretations and the Measurement Problem

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