The 1935 debate opposing Einstein, Podolsky and Rosen to Bohr elicited so many comments and developments, both theoretical and experimental, until this day, that the main point at stake at that time can be overlooked by modern readers, especially students. This paper draws the reader's attention to the historical background of Einstein's paper and Bohr's reply. We show that Einstein's definition of a complete physical theory is taken from Mach's criticism of atomic theory based upon classical-mechanical views. As for Bohr's definition of physical reality, it can be simply understood by reference to classical physics although it was embedded in the quantum-mechanical formalism.
The 1935 debate opposing Einstein, Podolsky and Rosen to Bohr elicited so many comments and developments, both theoretical and experimental, until this day, that the main point at stake at that time can be overlooked by modern readers, especially students. This paper draws the reader's attention to the historical background of Einstein's paper and Bohr's reply. We show that Einstein's definition of a complete physical theory is taken from Mach's criticism of atomic theory based upon classical-mechanical views. As for Bohr's definition of physical reality, it can be simply understood by reference to classical physics although it was embedded in the quantum-mechanical formalism.
ASPECTS OF THE DEBATE The debate between Niels Bohr and Albert Einstein concerning the interpretation of quantum mechanics extended from the fifth Solvay Conference in 1927 until the end of Einstein's life. The most dramatic exchange occurred in 1935, when Einstein, in collaboration with B. Podolsky and N. Rosen, published a paper in Physical Review entitled “Can quantum-mechanical description of physical reality be considered complete?”, concluding with a negative answer, and Bohr replied in the same journal, with a paper of the same title but giving a positive answer. Their arguments were restated, in some respects with greater clarity, in the Library of Living Philosophers volume on Einstein in 1949. The disagreements between Bohr and Einstein concerned not only the physical question expressed in the common title of their papers, but also philosophical questions about physical reality and human knowledge. Much light was thrown upon the Bohr–Einstein debate by the theorem of J. S. Bell (1964) and the experiments which it inspired. Bell showed that any physical theory which applies to a pair of spatially separated systems (as considered in the thought experiment of Einstein, Podolsky, and Rosen) and satisfies a certain locality condition will, in certain circumstances, disagree statistically with quantum mechanics. Consequently, the supplementation of the quantum mechanical description envisaged by Einstein and his collaborators (usually referred to as a “hidden variables theory”) must either violate the locality condition or clash with quantum mechanical predictions.
The Einstein-Podolsky-Rosen paradox is an old problem which started back in 1935 with an article in Physical Review titled ‘Does Quantum Mechanics Describe Physical Reality Completely?’ These authors assert that quantum mechanics, being inconsistent, cannot describe physical reality completely. In the present paper the nature of the inconsistency will be analyzed and it will be shown that the E.P.R. paradox is essentially of formal nature and that the apparent formal inconsistency may be regarded as a consequence of unjustifiable presupposition. According to quantum mechanical theory the states of a microscopic system may be represented by state vectors and in the absence of any disturbance from outside the state vectors will change continuously with time according to Schrodinger's equation.
This study posits that Bohr failed to defend the completeness of the quantum mechanical description of physical reality against Einstein–Podolsky–Rosen’s (EPR) paper. Although there are many papers in the literature that focus on Bohr’s argument in his reply to the EPR paper, the purpose of the current paper is not to clarify Bohr’s argument. Instead, I contend that regardless of which interpretation of Bohr’s argument is correct, his defense of the quantum mechanical description of physical reality remained incomplete. For example, a recent trend in studies of Bohr’s work is to suggest he considered the wave-function description to be epistemic. However, such an interpretation cannot be used to defend the completeness of the quantum mechanical description.
The famously controversial 1935 paper by Einstein, Podolsky, and Rosen (EPR) took aim at the heart of the flourishing field of quantum mechanics. The paper provoked responses from the leading theoretical physicists of the day, and brought entanglement and nonlocality to the forefront of discussion. This book looks back at the seminal year in which the EPR paper was published and explores the intense debate it unleashed. These conversations in print and in private correspondence offer significant insight into the minds of pioneering quantum physicists including Niels Bohr, Erwin Schrödinger and Albert Einstein himself. Offering the most complete collection of sources to date – many published or translated here for the first time – this text brings a rich new context to this pivotal moment in physics history. Both researchers and students in the history and philosophy of science, and enthusiasts alike, will find this book illuminating.
The EPR experiment is analysed in terms of ordinary quantum mechanics and shown to be compatible with the orthodox interpretation of this theory. There is no need to refer to Bohrs resolution of the EPR paradox, nor is it necessary to assume any further unusual properties of the quantum physical reality. In particular, it is shown that the EPR experiment does not contradict the fact that incommensurable properties cannot be objectivized simultaneously in a quantum mechanical system, and that the measuring process can be understood in terms of quantum theory as an interaction of the measuring apparatus and the object system. From these results it follows that there is no reason to search for modifications of the quantum theory which might be more convenient for a realistic interpretation of the EPR experiment. Furthermore, the EPR experiment cannot be used as a motivation for introducing hidden variables into the quantum theory. Experimental investigations which try to test quantum mechanics in respect to the possibility of introducing local hidden variables can therefore not be justified by the EPR paradox.
Ever since it first appeared in 1935, the famous paper by Einstein, Podolsky and Rosen, questioning the completeness of quantum mechanics as a theory, has courted controversy. The initial arguments with Bohr have never been forgotten or gone away; the ideas of Bell have remained; many experiments have been performed purporting to support the stance of Bohr. More recently, however, an experiment performed by a group in Basel has questioned this accepted position and, theoretically, this new perspective has received support from at least two sources. It is the work behind these two sources, especially the second, together with the experimental work at Basel, which form the basis for this examination of the present position as far as this extremely important position for physical science is concerned. Needless to say, considering the views expressed in these two approaches, it is also necessary and appropriate to consider some possible consequences if this new view becomes accepted. Due to the fact that the recent support for the Einstein, Podolsky, Rosen argument makes use of results in iso-mathematics, iso-mechanics and iso-chemistry, these possible consequences include the exact representation of nuclear data, the achievement of an attractive force between identical valence electrons with the ensuing exact representation of molecular data, the prediction of new clean energies and the prediction of the possible recycling of nuclear waste via stimulated decay—none of which is allowable utilising traditional quantum mechanics. Hence here, as well as discussing the resolution of the long standing issue provoked by the well-known Einstein, Podolsky, Rosen article, some of these consequences will be discussed with a view to provoking more general, open-minded discussion within the scientific community.