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Must a Quantum Mechanical Particle Sometimes be in Two Places at Once

John Hemp

Published Apr 1, 2019• 0 citations
OpenAlex

Abstract

In this short paper, we point out that the interference of probabilities in the double slit experiment, or in a particle interferometer, should not necessarily lead us to think that a quantum mechanical particle’s position is a meaningless concept or that continuous motion of a quantum mechanical particle is an impossibility. We do not need to conclude that a particle must sometimes be in two places at once, or that nature herself does not know exactly where a particle is etc. We show that the argument leading to that kind of conclusion, based on the interference of probabilities, is illogical when probability is viewed in a rational Bayesian fashion i.e. as accounting for rational degree of belief in an occurrence rather than the relative frequency of that occurrence in many trials. We lend support to the view that much progress may be made in the interpretation of the quantum formalism and in the formation of physical pictures of processes in quantum mechanics by viewing probability in a rational Bayesian manner. Keywords Quantum Mechanics, uncertainty principle, Bayesian probability, Realism, QBism.

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In this short paper, we point out that the interference of probabilities in the double slit experiment, or in a particle interferometer, should not necessarily lead us to think that a quantum mechanical particle’s position is a meaningless concept or that continuous motion of a quantum mechanical particle is an impossibility. We do not need to conclude that a particle must sometimes be in two places at once, or that nature herself does not know exactly where a particle is etc. We show that the argument leading to that kind of conclusion, based on the interference of probabilities, is illogical when probability is viewed in a rational Bayesian fashion i.e. as accounting for rational degree of belief in an occurrence rather than the relative frequency of that occurrence in many trials. We lend support to the view that much progress may be made in the interpretation of the quantum formalism and in the formation of physical pictures of processes in quantum mechanics by viewing probability in a rational Bayesian manner. Keywords Quantum Mechanics, uncertainty principle, Bayesian probability, Realism, QBism.
We offer a realist interpretation of non-relativistic quantum mechanics in which dynamical properties are properly possessed by the system in question, and are supposed to have definite values at any time. Like the QBists, we employ Bayesian probability, but we adopt something closer to the Bayesian statistics of E. T. Jaynes than to the subjective Bayesian statistics of B. de Fenetti employed by the QBists. Accordingly, we view calculated Bayesian probabilities as rational degrees of expectation of dynamical property values rather than as personal degrees of expectation of future (measurement) experiences. Probabilities are, for us, based on knowledge of the value of some dynamical property of the system, not on knowledge of previous experiences unassociated with system dynamical properties. As some Bayesians might, we take a probability equal to 1 not generally to indicate certainty but only (full) expectation; and we disallow probabilities of conjunctions of propositions claiming incompatible properties. Then, by reinterpreting and adding a little to the quantum formalism, we argue that we can maintain the advantages of the QBist interpretation. So, for us (as for the QBists), there is no unexplained collapse of the wave function, no need for ‘spooky action at a distance’, and no problem raised by the double slit experiment, the Kochen-Specker paradox or Bell type theorems. By holding on to a realist perspective, modelling (of ideal measurements, of system preparation processes etc.) is possible, and we can claim certain dynamical laws of quantum mechanics without leading to contradiction.
Abstract The theoretical results of quantum mechanics (QM) have been verified by experiments, but the probabilistic Copenhagen interpretation is still controversial, and many counterintuitive phenomena are still difficult to understand. To trace the origin of probability in QM, we construct the amplitudes of a space-time position in a multiparticle quantum objective system and find that the probability in QM originates from the particle number distribution rate in a unit volume near position r at time t in the multiparticle quantum objective system. Based on the origin of probability, the quantization conditions of action and the principle of least action for an elementary particle (referred to as particle) , we find that when a particle moves in space-time, it periodically and alternately exhibit particle and wave state. We have derived the formula for the fringe positions in the double-slit experiment with particles, a new certainty relation and the uncertainty relation, obtain the localized and nonlocalized spatiotemporal range of the particle, the apparent trajectory of the particle motion. Based on this, through rigorous mathematical derivation and analysis, we propose new physical interpretations of the quantum superposition state, wave-particle duality, the double-slit experiment, the Heisenberg uncertainty principle, and the quantum tunnelling effect, and these interpretations are physically logical and not counterintuitive.
Abstract In the 1950s and 1960s it was causing interest among physicists that in the formalism of quantum mechanics (complex-valued) ‘probability amplitudes’ obeyed laws similar to the laws obeyed by probabilities in the ordinary probability calculus. But this did not then lead decisively to the claim that probabilities should be represented by complex numbers. It became fashionable instead to regard probability amplitudes as an abstract concept from which actual probabilities could be derived by taking the squared moduli of the amplitudes. In this monograph, however, we make another attempt to show how probability amplitudes might after all be identified with actual probabilities. To do this, probability itself is interpreted in a rational Bayesian manner (i.e. as an extension of logic) and a new (complex-valued) probability theory is formulated that incorporates the uncertainty principle (i.e. that takes account of the fact that acquisition of knowledge of a quantum mechanical process generally interferes with it). Taking this probability theory as the new logic of science, and assuming certain physical laws and properties of matter, an interpretation of non-relativistic quantum mechanics is built up. It is consistent with the usual quantum mechanical formalism but allows a clear distinction to be made between the physical world and our knowledge of it.
Waves and particles are alternative modes of being for the elements of atomic dimensions. This feature appears to be evident at the experimental level but remains a conundrum at the theoretical level. The squared wavefunction |Ψ|2 yields the probability of finding a particle at a particular position and time, namely, the wave is conceived as a derivation or a physical condition of the particle and not a condition of the quantum. What the wavefunction represents, whether it really exists, whether it is a purely formal representation and if the observer influences the wavefunction are the major arguments of quantum mechanics (QM). The double nature of electrons, photons, and so on has been clearly recognized, and the two natures should be established by precise formulations. This work adheres totally to this methodological criterion and puts forward two formal definitions. The measurement process and wave collapse problems are also discussed. Finally, we verify the theoretical conclusions using the double slit experiment and the photoelectric effect. Probability plays a crucial role in the quantum literature, and the definitions of the wave and the particle should be illustrated by exploiting the probability theory; however, the various probability theories are not univocal and propose irreconcilable views. Therefore, in a preliminary stage, we unify the ontological and epistemic interpretations of probability using four theorems that have been already published. In summary, this work is developed on the basis of two methodological criteria, which seek to improve the probability theory and fix the definitional formulas of QM.
We show that it is possible to explain the quantum measurement process within the framework of quantum mechanics without any additional postulates. The key concept of the theory is decoherence, which appears as an inherent characteristic of quantum mechanics and results from the uncertainty relation. In contrast to environment-induced decoherence, this decoherence exists prior to a measurement being made. To clarify our idea, we examine three elemental experiments: a Stern-Gerlach-like experiment, the Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment, and the double-slit experiment. By considering the first experiment, we explain how the uncertainty relation between position and momentum introduces decoherence prior to measurement. Consideration of the EPR-Bohm experiment leads us to conclude that the correlation of the EPR pair is not a consequence of what is known as the collapse of the wave function. Our theory of decoherence can also be applied to experiments with continuous eigenvalues, such as the double-slit experiment. Consideration of the double-slit experiment leads us to understand how pure quantum mechanics describes the fact that quanta behave as interfering particles.
Abstract The theoretical results of quantum mechanics (QM) have been verified by experiments, but the probabilistic Copenhagen interpretation is still controversial, and many counterintuitive phenomena are still difficult to understand. To trace the origin of probability in QM, we construct the superimposed amplitudes of a space-time position in a multiparticle quantum objective system and find that the probability in QM originates from the particle number distribution rate in a unit volume near position r at time t in the multiparticle quantum objective system. Based on the origin of probability, We find that the state function of an elementary particle (hereinafter called particle for short) has precise physical meaning; that is, the particle periodically and alternately exhibits the particle state and wave state in time and space, obtain the localized and nonlocalized spatiotemporal range of the particle, the apparent trajectory of the particle motion. Based on this, through rigorous mathematical derivation and analysis, we propose new physical interpretations of the quantum superposition state, wave-particle duality, the double-slit experiment, the Heisenberg uncertainty principle, and the quantum tunnelling effect, and these interpretations are physically logical and not counterintuitive.