It is argued that the way towards understanding the experiments with visible light which purport to exhibit nonlocality lies in a return to the wave theory of light. A connection is also indicated between the present-day photon description and the pre-wave-theory corpuscular description, and hence we see that, essentially, the problem of nonlocality in physics was solved nearly two centuries ago by Young and Fresnel.

After analyzing the difficulties for a local realistic interpretation of quantum theory, it is argued that such an interpretation might be possible if some new postulates are added to the standard ones. We propose a stochastic interpretation of quantum theory, which involves the need of joint probability distributions for all relevant observables. The well known problems for the existence of joint distributions are solved by assuming that neither all Hermitian operators correspond to observables nor all density matrices represent physical states. (...) A research program along these lines is presented studying in particular the Maxwell quantum field and the Dirac field. (shrink)

It is argued that quantum mechanics must be interpreted according to the Copenhagen interpretation. Consequently the formalism must be used in a purely operational way. The relation between realism, hidden variables, and the Bell inequalities is discussed. The proof of impossibility of local hidden-variables theories (Bell's theorem) is criticized on the basis that the quantum mechanical states violating local realism are not physically realizable states.“Einstein had great difficulty in reaching a sharp formulation of Bohr's meaning. What hope then for the (...) rest of us.”—John S. Bell (Ref. 1, p. 189). (shrink)

We show that a semiclassical theory which takes account of vacuum fluctuations of the electromagnetic field is capable of giving a fully local realist description of the coincidence data from atomic-cascade experiments. Such a theory explains, in a unified manner, why there is a natural upper limit on detector efficiency, and also why, for certain values of the “hidden” variables, there is enhancement of the detection efficiency.

A brief and critical survey of wave-particle duality and nonlocality aspects of light is presented. A recent attempt to establish a reasonable framework for nonlocal realistic theories based on physically sound arguments and a proposed experiment to decide between such theories and the usual interpretation of quantum mechanical formalism are reviewed. It is shown that a nonlocal realistic approach may raise some new questions which could be answered by means of a program based on a sequence of experiments.

This paper deals with an (otherwise classical) two-(non-interacting) particle system immersed in a common stochastic zero-point radiation field. The treatment is an extension of the one-particle case for which it has been shown that the quantum properties of the particle emerge from its interaction with the background field under stationary and ergodic conditions. In the present case we show that non-classical correlations—describable only in terms of entanglement—arise between the (nearby) particles whenever both of them resonate to a common frequency of (...) the field. For identical particles the entanglement becomes maximum and must be described by totally (anti)symmetric states. (shrink)

In the popular literature of physics the electromagnetic field isoften treated as though it has an intrinsic particle nature. When thetheory is examined carefully, quantum theory only makes the weakerrequirement that the emission and absorption of light are restricted todiscrete amounts of energy. There are very few realizable experiments inoptics for which the classical Maxwell theory and the quantum theorymake a different prediction. I discuss some of these experiments with anemphasis on the distinction between what the experiments tell us aboutthe (...) measurement process, and what they tell us about the nature of thelight field. (shrink)

This paper describes a simple, causally deterministic model of quantum measurement based on an amplitude threshold detection scheme. Surprisingly, it is found to reproduce many phenomena normally thought to be uniquely quantum in nature. To model an \(N\) -dimensional pure state, the model uses \(N\) complex random variables given by a scaled version of the wave vector with additive complex noise. Measurements are defined by threshold crossings of the individual components, conditioned on single-component threshold crossings. The resulting detection probabilities match (...) or approximate those predicted by quantum mechanics according to the Born rule. Nevertheless, quantum phenomena such as entanglement, contextuality, and violations of Bell’s inequality under local measurements are all shown to be exhibited by the model, thereby demonstrating that such phenomena are not without classical analogs. (shrink)

A new realislic local model of light propagation and detection is described. The authors propose a novel stochastic model of low-intensity photon detection in which background noise is added to a part of the photon prior to absorption. In this model, in agreement with Planck, there is no quantization of the propagating field. The model has some similarities to theories advanced by E. Santos and T. Marshall in the last decade, but also has substantial deviations from these. A mechanism, conserving (...) energy and momentum, is proposed by which a sudden collapse of the wave-packet is avoided. The experimental Bell inequality violation of Aspect. Grangier and Roger [Phys. Rev. Lett.47, 460 (1981)]is discussed. The authors have carried out a computer simulation of a radio frequency (RF) analogue of the Einstein-Podolsky-Rosen thought experiment to illustrate how the manipulation of certain factors, especially signal to noise ratio, detector threshold and characteristics of the noise, enables the same Bell inequality to be either satisfied or violated by a realistic local model. Building on arguments by Santos. [Phys. Rev. A46. 3646 (1992)],the appropriateness of this Bell lest is discussed. Neither the authors' stochastic-optical model, nor their RF analogue, involves an enhancement assumption of the type defined by Clauser and Horne [Phys. Rev. D10, 526 (1974)]. (shrink)

We show that the divergence between the predictions of quantum optics and the local realist theory known as stochastic optics, for the extended type of photon-coincidence experiment described recently by de Caro, is of the same order of magnitude as for Aspect-type experiments. This means that, in such new experiments, as in those so far performed, counting statistics will have to be greatly improved before a discrimination between the two theories becomes possible.We also show that the outstanding difference between the (...) two theories is that, while stochastic optics uses a genuine, that is, positive, detection probability, the corresponding quantum formalism leads to a pseudoprobability. Nevertheless, there is a striking parallel, in that both theories recognize the phenomenon known as enhancement, and both describe it as having its origin in a mixing of the signal field with the zero-point field by a polarizing device. (shrink)