- Aerts, D. (1990). An attempt to imagine parts of the reality of the micro-world. In J. Mizerski, A. Posiewnik, J. Pykacz and M. Zukowski (Eds.), Problems in Quantum Physics (pp. 3-25). Singapore: World Scientific.
Abstract: Quantum mechanics is the theory used to 'describe' the processes that take place in the micro-world. From the start quantum mechanics has been a 'strange' theory, in the sense that it seemed to contradict in various ways the image of a micro-world consisting of 'objects' moving around in a three dimensional space, and interacting with each other in this three dimensional space. So from the advent of the theory a lot of disagreement existed as to the 'physical meaning' of this quantum theory, and a lot of discussions of a philosophical nature have taken place among the founding fathers. Only however during the last years experiments have been performed that, independently of the strangeness of the quantum theory, confront us directly with the strangeness of the reality of the micro-world. We have in mind the experiments on the EPR problem. In our opinion to be able to 'understand' the reality of this micro-world, it will be necessary to introduce new concepts, and become aware of old 'classical' prejudices. Certainly in not such a radical way as proposed by what is sometimes called the 'California interpretation' of quantum mechanics, but also in not such a vague way as is proposed by what is called the 'Copenhagen interpretation' of quantum mechanics. Since we nowadays have very 'specific' results, on very refined experiments, we should start 'imagining' how this 'micro-reality' is. The aim of this paper is to try something in this direction, and to propose what could be called a new discipline in theoretical physics. This discipline should investigate whether different kinds of realities (world-models) can correspond with the results of the experiments that we now have, and with the theoretical descriptions given by the quantum theory. And so although we agree that the quantum-world is a very strange one, our aim will be to show that it is not so strange as it looks at the first place. Just because 'a reality' can be much more complicated than one would imagine.
- Aerts, D. and Reignier, J. (1991). The spin of a quantum entity and problems of non-locality. In P. Lahti and P. Mittelstaedt (Eds.), Symposium on the Foundations of Modern Physics 1990: Quantum Theory of Measurement and Related Philosophical Problems (pp. 9-19). Singapore: World Scientific.
Abstract: We introduce a possible definition for the concept of non-locality in the quantum world, which seems to us a minimal operational definition, taking into account the results of actually performed experiments and reasonings about possible 'gedanken' experiments. The definition is the following: An entity is "non local" if it is possible to prepare it in a state such that it can be influenced from macroscopically separated regions of space by (macroscopically) local apparatus acting only in one (or several) of these separated regions at one time. We discuss two examples of spin superposition experiments which clearly show that quantum entities are non-local. In particular, we show that the familiar Stern- Gerlach experiment allows a nice illustration of this non-locality.
- Aerts, D. and Reignier, J. (1991). On the problem of non-locality in quantum mechanics. Helvetica Physica Acta, 64, pp. 527-547.
- Aerts, D., Veretennicoff, I. (1997). Niet-ruimtelijkheid als werktuig. In J. Van Pelt, Grenzeloze Wetenschap: Dertig Gesprekken met Vlamingen over Onderzoek. Leuven-Apeldoorn: Garant.
- Aerts, D. (1998). The entity and modern physics: the creation-discovery view of reality. In E. Castellani (Ed.), Interpreting Bodies: Classical and Quantum Objects in Modern Physics (pp.223-257). Princeton: Princeton University Press.
Abstract: The classical concept of 'physical entity', be it particle, wave, field or system, has become a problematic concept since the advent of relativity theory and quantum mechanics. The recent developments in modern quantum mechanics, with the performance of delicate and precise experiments involving single quantum entities, manifesting explicit non-local behavior for these entities, brings essential new information about the nature of the concept of entity. Such fundamental categories as space and time are put into question, and only a recourse to more axiomatic descriptions seems possible. In this contribution we want to put forward a 'picture' of what an 'entity' might be, taking into account these recent experimental and theoretical results, and using fundamental results of the axiomatic physical theories (describing classical as well as quantum entities) such as they have been developed during the last decade. We call our approach the 'creation-discovery view' because it considers measurements as physical interactions that in general entail two aspects: (1) a discovery of an already existing reality and (2) a creation of new aspects of reality during the act of measurement. We analyze the paradoxes of orthodox quantum mechanics in this creation-discovery view and point out the pre-scientifc preconceptions that are contained in the well-known orthodox interpretations of quantum mechanics. Finally we identify orthodox quantum mechanics as a first order non classical theory, and explain in this way why it is so successful in its numerical predictions.
- Aerts, D., Broekaert, J. and Smets, S. (1998). Inconsistencies in constituent theories of world views: quantum mechanical examples. Foundations of Science, 3, pp. 313-340.
Abstract: We put forward the hypothesis that there exist three basic attitudes towards inconsistencies within world views: (1) The inconsistency is tolerated temporarily and is viewed as an expression of a temporary lack of knowledge due to an incomplete or wrong theory. The resolution of the inconsistency is believed to be inherent to the improvement of the theory. This improvement ultimately resolves the contradiction and therefore we call this attitude the 'regularising' attitude; (2) The inconsistency is tolerated and both contradicting elements in the theory are retained. This attitude integrates the inconsistency and leads to a paraconsistent calculus; therefore we will call it the paraconsistent attitude. (3) In the third attitude, both elements of inconsistency are considered to be false and the 'real situation' is considered something different that can not be described by the theory constructively. This indicates the incompleteness of the theory, and leads us to a paracomplete calculus; therefore we call it the paracomplete attitude. We illustrate these three attitudes by means of two 'paradoxical' situations in quantum mechanics, the wave-particle duality and the situation of non locality.
- Aerts, D. (1999). The stuff the world is made of: physics and reality. In D. Aerts, J. Broekaert and E. Mathijs (Eds.), Einstein meets Magritte: An Interdisciplinary Reflection (pp. 129-183). Dordrecht: Kluwer Academic. Archive reference and link: http://uk.arxiv.org/abs/quant-ph/0107044.
Abstract: Taking into account the results that we have been obtained during the last decade in the foundations of quantum mechanic we put forward a view on reality that we call the 'creation discovery view'. In this view it is made explicit that a measurement is an act of a macroscopic physical entity on a microphysical entity that entails the creation of new elements of reality as well as the detection of existing elements of reality. Within this view most of the quantum mechanical paradoxes are due to structural shortcomings of the standard quantum theory, which means that our analysis agrees with the claim made in the Einstein Podolsky Rosen paper, namely that standards quantum mechanics is an incomplete theory. This incompleteness is however not due to the absence of hidden variables but to the impossibility for standard quantum mechanics to describe separated quantum entities. Nonlocality appears as a genuine property of nature in our view and makes it necessary to reconsider the role of space in reality. Our proposal for a new interpretation for space makes it possible to put forward an new hypothesis for why it has not been possible to unify quantum mechanics and relativity theory.