The term “experimental philosophy” has been used to refer to the solution of what were considered philosophical problems by means of laboratory experiments. A recent example of this was the experimental violation of the Bell inequality, which ruled out certain philosophically appealing “realist local” theories as alternatives to quantum mechanics (QM). Following the spirit of such experimental philosophy, this paper proposes a feasible test between two different interpretations concerning the nature of “mixtures” in QM. The use of delayed coincidence techniques seems to show that the process of mixing beams of light in different polarizations is reversible, favoring a weak version of the so-called “ignorance interpretation” over the “instrumentalist” view.
The term “experimental philosophy” has been used to refer to the solution of what were considered philosophical problems by means of laboratory experiments. A recent example of this was the experimental violation of the Bell inequality, which ruled out certain philosophically appealing “realist local” theories as alternatives to quantum mechanics (QM). Following the spirit of such experimental philosophy, this paper proposes a feasible test between two different interpretations concerning the nature of “mixtures” in QM. The use of delayed coincidence techniques seems to show that the process of mixing beams of light in different polarizations is reversible, favoring a weak version of the so-called “ignorance interpretation” over the “instrumentalist” view.
Abstract It used to be assumed that the differences between “interpretations” of quantummechanics are philosophical and not physical. The experimental test of the original EPR “thought experiment” by Aspect et al., using the Bell inequalities, eliminatedthe Bohm-Aharanov local hidden variables, demonstrating that the so-called interpretations are distinct theories, amenable to experimental testing, and not merely philosophically different “interpretations”. In this paper I present a sequence of experiments, doable by current technology, to distinguish between various “interpretations” of Quantum Mechanics.
The incompatibility of Orthodox Quantum Mechanics with philosophical realism poses a serious challenge to scientists upholding such a philosophical doctrine. The desire to find a solution to this and other conceptual problems that quantum mechanics confronts has motivated many authors to propose alternative versions to Orthodox Quantum Mechanics. One of them is the Spontaneous Projection Approach, a theory grounded on philosophical realism. It has been introduced in previous papers and, with a few exceptions, it yields experimental predictions coincident with those of Orthodox Quantum Mechanics. One of these exceptions is analyzed in detail. The difference in predictions becomes apparent in a suggested experiment which could put both theories to the test.
Over the past three decades or so, experiments of the type called Gedanken have become real. Recall the Schrödinger quote from Chapter 8: “… we never experiment with just one electron or atom or (small) molecule.” This is no longer true. We can do experiments involving single atoms or molecules and even on single photons, and thus it becomes possible to demonstrate that the “ridiculous consequences” alluded to by Schrödinger are, in fact, quite real. We have already discussed some examples of single-photon experiments in Chapter 6, and in Chapter 10 we shall discuss experiments performed with single atoms and single trapped ions. In the present chapter, we shall elaborate further on experimental tests of fundamentals of quantum mechanics involving a small number of photons. By fundamental tests we mean tests of quantum mechanics against the predictions of local realistic theories (i.e. hidden variable theories). Specifically, we discuss optical experiments demonstrating violations of Bell's inequalities, violations originally discussed by Bell in the context of two spin-one-half particles. Such violations, if observed experimentally, falsify local realistic hidden-variable theories. Locality refers to the notion, familiar in classical physics, that there cannot be a causal relationship between events with space-like separations. That is, the events cannot be connected by any signal moving at, or less than, the speed of light; i.e. the events are outside the light-cone. But in quantum mechanics, it appears that nonlocal effects, effects seemly violating the classical notion of locality in a certain restricted sense, are possible.
In 1935, Einstein, Podolsky, and Rosen (EPR) argued that (then new) quantum mechanics was incomplete. At the heart of EPR’s paradox was the strange non-local nature of an entangled state which allowed EPR to simultaneously assign local values for position and momentum of a particle. In 1964, John Bell proposed an inequality (Bell’s inequality) that must be satisfied by any local realistic theory. The experimental confirmation of quantum physics, i.e., the experimental test of Bell’s inequality, required a pair of particles in an entangled state. The experiments first performed in the early 1970s, followed by a series of experiments until now, have confirmed the violation of Bell’s inequality, strongly implying that local realistic descriptions of nature are not consistent with experimental observations. The early simplistic view of entanglement has now been significantly expanded to include mixed states and multiple particles. Moreover, theoretical and experimental studies on the nature of entanglement have led to quantum information science where entanglement is an essential resource. In this article, we briefly review the early experiments on Bell’s inequality and experimental attempts to close “loopholes” as well as some key experiments on quantum information.
This paper explores how experiments influence the reception of interpretations of quantum mechanics, and also other relations between experiments and interpretations in that field. We start by surveying the struggle of different schools of philosophy of science in the 19th and early 20th centuries to adapt to the scientific advances, and then give a brief overview of realist and antirealist interpretations in quantum mechanics. Eight different types of relations between interpretations and experiments are then examined, with case studies from the history of quantum mechanics. (1) Many interpretations agree with all of the predictions of the instrumentalist interpretation, which is a good strategy for survival. (2) Some interpretations make different predictions that are not testable. (3) Other interpretations constitute ‘a different theory’ and are testable, although sometimes this is not anticipated by the interpretation. (4) Some interpretations have generated many variations, by adjustment of parameters or hypotheses, and part of these variations have been tested and ruled out by experiment. (5) At times experiments reinforce an interpretation. (6) Some experiments lead to a refinement of the interpretation. (7) There are experiments that suggest the creation of an interpretation. (8) And there are cases in which experiments are suggested by an interpretation, while not affecting its rivals.
My aim in this dissertation is to defend a realist interpretation of quantum mechanics.Firstly, I present considerations based on certain general features of theories in the natural sciences which indicate that realism affords a better account of those theories than instrumentalism.In particular, I consider certain issues surrounding the cognitive status of theories, including the role of models, the status of scientific explanation, and the referential character of theoretical terms.Secondly, I develop a detailed realist theory of measurement based on the notion of quantity terms as designators of objective properties of, and relations among, existing entities.I contrast this with the leading instrumentalist theories of measurement, and I argue that the realist theory is the better account of both the logic and practice of scientific measurement.Finally, I consider a number of objections to realism that arise because of certain theoretical features peculiar to quantum mechanics.In the course of this discussion, I consider crucial experimental evidence for the "dual" nature of microentities, various criteria of reality proposed by philosophers of science, the peculiar features of quantum mechanical measurement, and the status of causality in quantum mechanics.I argue that while certain realist viii ix interpretations of the quantum theory, namely the wave and wavicle interpretations, are unsatisfactory, an interpreta tion which construes micro-entities as existing particles is a tenable account.CHAPTER I ignored the considerations which arise at those more general levels of inquiry, but one can not adequately assess the status of quantum mechanics with respect to both realism and instrumentalism apart from those considerations.In the second two chapters of the dissertation, I shall argue that realist interpretations of quantitative theories in the natural sciences are preferable to instrumentalist interpretations.Then in the remainder of the dissertation, I shall go on to argue that realism is tenable at the quantum mechanical level despite the features peculiar to that theory.CHAPTER II THE COGNITIVE STATUS OF THEORIES transitions from one set of experiential statements to another.This view is in marked contrast to that of the realist who regards such terms as referential.This divergence in opinion between realists and instrumentalists about the referential character of theoretical terms leads to a related dispute over the role of models in the inter pretation of scientific theories.Before contrasting the various philosophical positions on this issue, it will be necessary to sort out different senses of the term "model."Upon inspecting the literature surrounding this dispute, it seems that much of the controversy about the role of models stems from a failure to make such distinctions.I will begin this task by distinguishing between 13 model-structures and model-objects.A model-structure is a definitely specifiable schema of mathematical-logical relationships which is exhibited by and can be abstracted from a set of objects.Any set of objects which exhibits a model-structure constitutes a set of model-objects.With respect to any particular scientific theory, there may be a variety of model-objects that scientists employ for various purposes.For example, in the kinetic theory of gases, one can distinguish the following.Firstly, there is the set of molecules themselves, the theoretical entities which we shall 13.For further detail in this regard, see Henry C. Byerly, "Model-Structures and Model-Objects," British Journal for the Philosophy of Science.Vol. 20, 1969, pp.135-144.i In fact, if one were to make that claim, I do not see how it could be supported without again falling prey to Maxwell's criticism cited above.And if one is simply troubled by the "ontological risk" involved in asserting the existence of theoretical entities because of the tentativeness of the corresponding theories, it should be noted that the risk of being wrong is a small price to pay for the potentially deeper understanding of nature that scientific theories afford us in the light of realist commitments.