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NeuroQuantology

The Measurement Problem in Quantum Mechanics: Well, Where’s the Problem?

Sultan Tarlacı

Published Dec 9, 2011• 5 citations
Publisher

Abstract

The most discussed thought experiment in quantum mechanics (QM) is the one of the dead+living cat, which sets out to explain what is known as the measurement problem. Since the first years of QM, and despite various arguments, the widespread beliefs of the past few years have tended towards including a conscious observer in the act of measurement. Various different opinions have been expressed on the measurement problem by various schools of thought and leading physicists, but none of them has been decisive. Especially, the introduction of an observer (human-brain-consciousness-mind-intelligence) carrying out measurements into the experiment or into the setup of the experiment has led to even more complex problems. Today also, new solutions are being put forward. This article deals with the thought experiment of Schrodinger’s cat and suggestions for alternative solutions by introducing a conscious observer. NeuroQuantology |June 2012 | Volume 10 | Issue 2 | Page 216-229

DOI
10.14704/nq.2012.10.2.444

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The most discussed thought experiment in quantum mechanics (QM) is the one of the dead+living cat, which sets out to explain what is known as the measurement problem. Since the first years of QM, and despite various arguments, the widespread beliefs of the past few years have tended towards including a conscious observer in the act of measurement. Various different opinions have been expressed on the measurement problem by various schools of thought and leading physicists, but none of them has been decisive. Especially, the introduction of an observer (human-brain-consciousness-mind-intelligence) carrying out measurements into the experiment or into the setup of the experiment has led to even more complex problems. Today also, new solutions are being put forward. This article deals with the thought experiment of Schrodinger’s cat and suggestions for alternative solutions by introducing a conscious observer.
NeuroQuantology |June 2012 | Volume 10 | Issue 2 | Page 216-229
Erwin Schrodinger first described the thought-experiment which has since become known as 'the paradox of Schrodinger's cat' 51 years ago. In recent years, popular accounts of quantum mechanics have tended to adopt one or other of the philosophically most extreme solutions to this paradox, i.e. the consciousness hypothesis or the many worlds interpretation. The author attempts to redress the balance by describing what he takes to be the orthodox solution to the paradox which explains the paradox, without recourse to such counterintuitive notions as a cat simultaneously dead and alive or a universe continually splitting into multiple worlds, as being due to a misapplication of the quantum formalism.
Despite the spectacular success of quantum mechanics (QM) over the last 80 years in explaining phenomena observed at the atomic and subatomic level, the conceptual status of the theory is still a topic of lively controversy. Most of the discussion centers around two famous paradoxes (or, as some would have it, pseudoparadoxes) associated, respectively, with the names of Einstein, Podolsky, and Rosen (EPR) and with Schrodinger's cat. In this Viewpoint, I will concentrate on the paradox of Schrodinger's cat or, as it is often known (to my mind somewhat misleadingly), the quantum measurement paradox.
Schrodinger's Cat: Empirical research into the radical subjective solution of the measurement problem\n\nDick J. Bierman & Stephen Whitmarsh\n\n \n\nThe most controversial of all solutions of the measurement problem holds that a measurement is not completed until a conscious observation is made.\n\nIn other words quantum physics is a science of potentialities and the measurement i.c. the conscious observation brings about the reality by reducing the state vector to one of the Eigen-states.\n\nIn a series of experiments modeled after the famous experiment by the Shimony group we have explored the brain responses of observers of a quantum event. \n\nIn about 50% of the exosures this quantum event had already been observed about one second earlier by another person. This random manipulation was unknown to the final observer. \n\nThe first experiment along these lines gave suggestive evidence for a difference in brain responses dependent on the manipulation. In subsequent experiments quantum events were mixed with classical events and the results of these experiments that have been reported elsewhere were ambiguous. \n\nIn a final experiment we are trying to solve the paradoxical results obtained so far. In this experiment the final observer receives detailed information about the type of event that (s)he observes. Also the experimental protocol is such that not only pre-observed events cannot be distinguished from not pre-observed events on the basis of their physical characteristic but neither on the basis of inter-event time distributions.
Some of the quantum mechanical conceptual problems, their current status, and related theoretical developments are reviewed. The characteristics of the entangled quantum states are analyzed, and new experiments and quantum information applications involving such states are discussed. The well-known paradox of Schroedinger's cat (the impossibility of observing superpositions of macroscopically distinct states that are predicted by quantum mechanics) is discussed. It is shown that decoherence (arising when a quantum system is measured in such a way that some information about its state is recorded in its environment) prevents the distinguishing of a superposition and the corresponding mixture. This overcomes the difficulties associated with the paradoxical nature of quantum measurement provided we remain within the framework of the theory of open systems. Other conceptual difficulties, while actually lying outside physics, are now the subject of much research and have already led to new interesting interpretations of quantum mechanics. The suggestion of Wigner and others that the observer's consciousness be included in the theory of quantum measurement is discussed in this context. A hypothesis is put forward which might enable the functioning of consciousness to be described in quantum measurement terms.
The implementation of quantum theory was presented to our macroscopic world by the “cat” thought experiment (Gedanken experiment) suggested by Erwin Schrodinger in 1935. In the same way, Pavlov’s dog with its learning by conditioned reflexes was a similar symbol of Newtonian physics representing the deterministic view, and the cat as an animal became the symbol of quantum mechanics. Thought experiments are a common technique in physics. Before everything, it is important to see whether the experiment can be carried out at all, and it is unimportant how complex the relevant techniques to be used in the experiment. This is because there is only a design and a thought experiment. Imagination and materials are unlimited, and the only constraining factors are the laws of mathematics and physics. If you feel sorry for the cat, you might prefer the experiment suggested by Einstein, which uses a box containing a bomb, a photon, an electron, or playing cards. In this article, we reviewed possible solutions of the quantum measurement problem or quantum wavefunction collapse. NeuroQuantology | September 2012 | Volume 10 | Issue 3 | Page 519-531
In recent decades, progress in the field of neurosciences has triggered an interest in understanding mind-brain relationships. Quantum Mechanics (QM) has been present in the debate from its beginnings through the well-known measurement paradox. The standard interpretation of QM considers two basic, fundamentally irreducible, processes: the deterministic evolution of the wave-function according to the Schrodinger equation, once the initial conditions have been settled; and the indeterministic wave-function collapse into one of the possible outcomes, after performing a specific measurement. So, QM would point to the limits of a purely deterministic view of nature and, in particular, of brains. Nevertheless, QM’s relevance for the brain’s physics is still to be proven. Detractors of the QM influence are confident of the role of decoherent processes at different physical scales in order to ensure a classical deterministic behavior of the brain. However, little attention is paid to the epistemic implications of invoking decoherence for the mind-brain problem. In this paper, (i) we present lasting QM models stating a specific view of human consciousness and make explicit their position regarding the relationship between the physical activity of neurons and/or networks of neurons and the phenomenal conscious experience; (ii) we review the main criticisms of the relevance of QM in the brain and, most importantly, we bring out the philosophical implications behind the usual recourse to decoherence in the transition from the quantum to the classical world, explaining why the mind-brain problem and the measurement paradox should not be disentangled.