In 2018, a new systematic approach to solving the interpretation problem of quantum theory was published under the title "Realistische Quantentheorie" (in German). In the present document, the main results of this approach are reported (in English), with the necessary mathematical proofs being provided in an appendix. The approach comprises a canonical modeling of quantum reality, a precise formulation of the deterministic and probabilistic laws, proof of logical consistency of these laws (thus solving the well-known no-go problems), unequivocal definition of the quantum state and clarification of its ontological status, solution to the problem of measurement, and clarification of the role played by the reduction of the quantum state. A more detailed description of this solution to the interpretation problem can be found in the summary (pp. 7-9 of this document). Ambiguities of the Copenhagen interpretation are avoided as are speculative concepts of many-worlds theories or the attempt to adhere to outdated particle concepts (Bohmian mechanics). Also avoided are pseudo-philosophical speculations about subjectivism or phenomenalism as expressed in the assertion that the world is "nothing but information". A postprint of the original publication is available in the Zenodo repository (zenodo.7750648) and in the Mathematical Physics Preprint Archive (mp_arc 23-6), see links below under "Related works" / "Is derived from". Remark: The present text mostly corresponds to the "Short Account" published earlier (in German), which is also available in the Zenodo repository (zenodo.8245998, see link below). However, the necessary proofs have been extracted from the original publication and added here in a translated version.
In 2018, a new systematic approach to solving the interpretation problem of quantum theory was published under the title "Realistische Quantentheorie" (in German). In the present document, the main results of this approach are reported (in English), with the necessary mathematical proofs being provided in an appendix. The approach comprises a canonical modeling of quantum reality, a precise formulation of the deterministic and probabilistic laws, proof of logical consistency of these laws (thus solving the well-known no-go problems), unequivocal definition of the quantum state and clarification of its ontological status, solution to the problem of measurement, and clarification of the role played by the reduction of the quantum state. A more detailed description of this solution to the interpretation problem can be found in the summary (pp. 7-9 of this document). Ambiguities of the Copenhagen interpretation are avoided as are speculative concepts of many-worlds theories or the attempt to adhere to outdated particle concepts (Bohmian mechanics). Also avoided are pseudo-philosophical speculations about subjectivism or phenomenalism as expressed in the assertion that the world is "nothing but information". A postprint of the original publication is available in the Zenodo repository (zenodo.7750648) and in the Mathematical Physics Preprint Archive (mp_arc 23-6), see links below under "Related works" / "Is derived from". Remark: The present text mostly corresponds to the "Short Account" published earlier (in German), which is also available in the Zenodo repository (zenodo.8245998, see link below). However, the necessary proofs have been extracted from the original publication and added here in a translated version.
In 2018, a new and systematic solution to the interpretation problem of quantum theory was published (in German language) under the title of "Realistische Quantentheorie". In the present document, a postprint of this publication can be found, together with an English summary. The solution considered here comprises a canonical modelling of quantum reality, a precise formulation of the deterministic and the probabilistic laws, proof of the logical consistency of these laws (thus solving the well-known no-go-problems), unequivocal definition of the quantum state and clarification of its ontological status, solution to the problem of measurement and clarification of the role played by the reduction of the quantum state. Ambiguities of the Copenhagen interpretation are avoided as well as speculative concepts of many worlds theories or the attempt to adhere to outdated particle concepts (Bohmian mechanics). Also avoided are pseudo-philosophical speculations about subjectivism or phenomenalism as expressed in the assertion that the world is "nothing but information". For a more detailed description of this theory see the abstract as well as the summary in the PDF document.
Some mostly recent theoretical and mathematical advances can be linked together to yield a new consistent interpretation of quantum mechanics. It relies upon a unique and universal interpretative rule of a logical character which is based upon Griffiths consistent historie. Some new results in semi-classical physics allow to derive classical physics from this rule, including its logical aspects, and to prove accordingly the existence of determinism within the quantum framework. Together with decoherence, this can be used to retrieve the existence of facts, despite the probabilistic character of the theory. Measurement theory can then be made entirely deductive. It is accordingly found that wave packet reduction is a logical property, whereas one can always choose to avoid using it. The practical consequences of this interpretation are most often in agreement with the Copenhagen formulation but they can be proved never to give rise to any logical inconsistency or paradox.
In the well known Copenhagen interpretation of Quantum mechanics, advocated by N. Bohr, the physical objects and the experimental results can be described only in a macroscopic language, leaving any possible microscopic description as unspeakable. This point of view has been deepened by C. Rovelli in the relational interpretation of Quantum mechanics. Most of the alternative interpretations, which try a detailed microscopic description of physical phenomena and of their evolution, have in common the explicit introduction of the wave function as the basic element of the theory. These interpretations require the notion of quantum state as the fundamental concept of the theory, which is the typical unspeakable physical element according to the Copenhagen interpretation. The two basic physical entities are intimately bound together by the integrity of the wave function. These interpretations are usually indicated as realistic. It is well known that the use of the wave function and its time evolution in the description of the physical processes leads unavoidably to some difficulties or so-called paradoxes. The measurement problem is at the center of these difficulties, mainly because it requires the introduction of the reduction process of the wave function, which is not included explicitly within the mathematical formalism of Quantum Mechanics. In this paper we build up and propose a model which goes beyond the standard formalism and which is able to solve the measurement problem and all the other difficulties which, in a way or in another, are related to it.
This work presents a historical-epistemological analysis of the foundations of quantum mechanics. From a philosophical point of view, the relationships between quantum mechanics and scientific realism are highlighted, as well as the influence of the neo-positivist philosophy of the first decades of the 20th century. The great significance of measurement in the context of quantum mechanics is underlined, as an essential element in providing a coherent description of reality moving from the microcosm to the macrocosm, as well as the role that the measurement apparatus and the consciousness of the observer assume during the act of measurement, the ontological problem, the problem of the objectification of the wave function and the problem of the definition of discernibility. This is followed by an overview of the most important alternative proposals to the standard interpretation (Copenhagen interpretation), with particular reference to hidden variable theories, and other alternatives to standard quantum mechanics that profoundly modify the vision of reality, such as the Everett’s many-worlds theory, the QBism, the unified holistic approach.
We present a historical-epistemological analysis of the foundations of quantum mechanics, highlighting the relationships between quantum mechanics and scientific realism, as well as the influence of the neo-positivist philosophy of the first decades of the 20th century. The great significance of the measurement process in the context of quantum mechanics is underlined as an essential element in providing a coherent description of reality, moving from micro to macrocosm, as well as the role that the measurement apparatus and the consciousness of the observer assume during the act of measurement, the related ontological problems, the question of the objectification of the wave function, and that of the definition of discernibility. We consider also an overview of the most important alternative proposals to the standard interpretation of quantum mechanics (Copenhagen interpretation), with particular reference to hidden variable theories and other alternatives to standard quantum mechanics philosophical approach, that are modifying the vision of reality, such as the Everett’s many-worlds theory, the QBism and unified holistic approaches, such as the Primordial Dynamic Space.
Even after a hundred years of quantum theory, the true meaning of the quantum state has not yet been clearly understood. Does a pure quantum state, described by a wave function φ, represent a real physical quantity, comparable to position and momentum in classical mechanics, or does it, even as a pure state, only have a statistical significance, similar to a probability distribution? In this paper, we show that there is no contradiction between these two interpretations. Two concepts must be distinguished here: on the one hand, physical objects, which have a finite lifetime, and on the other hand, subsystems (i.e., tensor factors) of the Hilbert space of the universe. A complete description of an object at a point in time t is given by a linear subspace A of its Hilbert space, which, in the case of dim A = 1, can be specified by a wave function φ as A = [φ]. However, for every subsystem Q, for each point in time t, and for every condition B, the conditional quantum state W = W(Q,t|B) can be defined as a statistical operator on the Hilbert space of Q. Using W, certain (conditional) probabilities can be calculated. In the case of rank W = 1, the operator W can also be specified by a wave function φ, namely as W = |φ><φ|. It is the subsystems of the Hilbert space that play the role of "quantum systems" in the Copenhagen formalism, and the quantum states defined for them behave exactly as described by this formalism. If a wave function φ represents the description of a (quantum) object, then we are dealing with a real physical property, that is, φ plays an "ontic" role. However, if φ represents a quantum state, then its role is merely "statistical". If, in this case, condition B corresponds to the knowledge of a subject, φ plays an "epistemic" role. Additional Remarks The reasoning in this paper is largely based on a new systematic approach to solving the interpretation problem of quantum theory, which was originally published in 2018 (in German) under the title "Realistische Quantentheorie". A comprehensive account of this approach (in English) was published in February 2026 under the title "Realistic Quantum Theory: Solving the Interpretation Problem". It is available in the Zenodo repository (zenodo.18644694, see link below under "Related works" / "References"). The present document provides an English version of an earlier paper in German under the same title, which is also available in the Zenodo repository (zenodo.10694813, see link below).