yet have definite shapes at any moment? Could it be that quanta have statistical definite properties, wave- and particle properties at the same time? These questions need an answer to reach some consensus in physics and to solve some of the most urgent problems in physics. These questions will be answered in this paper. Also the probabilities in Bell experiments, predicted by quantum mechanics, are made visible and their explanation is accounted for mathematically.
yet have definite shapes at any moment? Could it be that quanta have statistical definite properties, wave- and particle properties at the same time? These questions need an answer to reach some consensus in physics and to solve some of the most urgent problems in physics. These questions will be answered in this paper. Also the probabilities in Bell experiments, predicted by quantum mechanics, are made visible and their explanation is accounted for mathematically.
Quantum mechanics is an immensely successful theory, occupying a unique position in the history of science. It has solved mysteries ranging from macroscopic superconductivity to the microscopic theory of elementary particles and has provided deep insights into the nature of vacuum on the one hand and the description of the nucleon on the other. Whole new fields such as quantum optics and quantum electronics owe their very existence to this body of knowledge. However, despite the stunning successes of quantum mechanics, there is no general agreement on the conceptual foundations and interpretation of the subject. The theory provides unambiguous information about the outcome of a measurement of a physical object. However, many feel that it does not provide a satisfactory answer to the nature of the “reality” we should attribute to the physical objects between the acts of measurement. The conceptual difficulty comes about because the wave function |ψ〉 is usually given by a coherent superposition of various distinguishable experimental outcomes. If we denote the collection of states that represent the possible outcomes of an experiment by |ψ j 〉, then |ψ〉 = ∑ j c j |ψ j 〉 where c j = 〈ψ j |ψ〉. The probability of the outcome |ψ j 〉 is P j =|c j | 2 . In the process of measurement, the so called collapse of the wave function takes place and a single, definite state |ψ i 〉 of the physical object is chosen. The difficulty comes about in the interpretation of the mechanism by which this definite state is chosen from amongst all the possible outcomes.
Quantum experiments detect particles, but they reveal information about wave properties. No matter how quanta are detected, they always express the local net state of the corresponding wave-function. The mechanism behind this process is still a mystery. However, quantum wave-functions evolve like classical waves. If they determine all the observations, why do they entail "weird" phenomena? In particular, why do they produce conceptual problems, such as the EPR paradox? It turns out that all the major interpretations in quantum mechanics are particle-based ontologies. Variables of fundamental interest, such as momentum and position, are assumed to reflect the input states of discrete entities, even when their evolution is predicted by wave equations. Here I show that a whole class of microscopic phenomena, including entanglement, can be interpreted without contradictions if the variables of quantum mechanics are actually treated as wave properties. The main recommendation is to assume that sharp spectral states are transient outcomes of superposition, rather than permanent input components.
In spite of the recent extraordinary progresses of experimental techniques it does not seem that, after more than seventy years from the birth of quantum mechanics, a unanimous consensus has been reached in the physicist's community on how to understand the "strange" properties of quantons, the wavelike/particlelike objects of the quantum world. In the first paragraph I will briefly recall some results on the problem of decoherence in large quantum systems, which at the same time may be viewed as an attempt of providing a "realistic" physical interpretation of the standard mathematical formulation of the theory. In the following ones I will present a derivation from first principles of the Wigner representation of quantum mechanics in phase space which eliminates altogether from the theory the Schrödinger waves and their questionable properties. This approach leads to the conclusion that the wave/particle duality has nothing to do with "probability waves", but is simply the manifestation of two complementary aspects (continuity vs. discontinuity) of an intrinsically nonlocal physical entity (the quantum field) which objectively exists in ordinary three dimensional space.
After the review by Hauge and Stovneng the old question of "How long does it take to tunnel through the barrier?" has not still lost its relevance. As before, there is no clear answer to this question even for the one-dimensional completed scattering (OCS). In this paper we show that this seemingly simple question stands alongside with such fundamental problems of quantum mechanics (QM) as the Schrodinger's-cat and and EPR-Bohm paradoxes. Their common feature is that the states of a scattered particle, a radioactive atom and electron EPR-pair represent pure {\it micro-cat} states. It is widely accepted that the EPR-Bohm paradox implies the non-existence of local hidden variables (LHVs), the cat paradox represents a macro-objectification problem and the tunneling time is an observer-dependent quantity whose definitions must be 'operational'. At the same time, according to the probabilistic approach (Accardi, Khrennikov, Philipp, Hess {\it et al.}) to Bell's inequality that underlies the EPR-Bohm experiments, its experimental violation means simply that it contains probability distributions associated with mutually incompatible statistical data. We argue that this approach must be extended onto micro-cat states because they describe, too, mutually incompatible statistical data. The current practice to interpret the squared modulus of a micro-cat state as the probability density should be recognized as erroneous. It is this practice that makes QM incompatible with classical physical theories and, thereby, makes the micro-world 'unspeakable'. The known 'operational' tunneling-time concepts, elaborated in line with this practice, are logically inconsistent. We argue that the TTP and the cat paradox must be solved at the level of single electrons and atoms, without resorting to environment and measurement contexts. We present a new model of the OCS and solve the TTP on its basis.
In Bell-test experiments two kinds of probabilities appear: calculated probabilities and measured probabilities. The calculated probabilities (Bell's) cannot be detected by the detectors, whereas the measured probabilities (QM) are being detected by the detectors indirectly. The two kinds of probabilities are very different but both can be accounted for in a local-real way. They both can be made visible as projections of one and the same vector space in different directions. The differences between the kinds of probabilities are caused by the fact that detectors and observers perceive things like: vectors, vector spaces, particles and pairs of particles, differently. Observers perceive calculated probabilities (Bell) and detectors detect measured probabilities (QM) but only indirectly. In the paper both kinds of probabilities are being defined exactly. The exact definition of the probabilities makes clear why they appear as they do.
Ever since the beginning of quantum mechanics, the measurement problem has been a subject of sometimes discontinued but nevertheless recurrent concern. As students, most physicists have raised questions about it, but the spectacular and renewed successes of quantum theory were a strong incentive for them to work out applications without further worrying about foundations. In each generation, however, some dissatisfaction reemerges, which leads to slow progress, and we may expect that the measurement problem will some day be cleared up rather than forgotten. The situation recalls statistical mechanics, the foundations of which still give rise to scientific discussions, in spite of more than one century’s achievements. Actually, the paradoxes of irreversibility and of Maxwell’s demon share some common features with quantum measurements, to wit, they involve probabilities in a crucial fashion and their explanation requires elucidating the role of the observer.