Problems and Promises of the Ensemble Interpretation of Quantum Mechanics

Lee Smolin

Dipankar Home, M. A. B. Whitaker

Glenn F. Webb

Alexander A. Pechenkin

The article takes under consideration three versions of the ensemble (statistical) interpretation of quantum mechanics and discusses the interconnection of these interpretations with the philosophy of science. To emphasize the specifics of the problem of interpretation of quantum mechanics in the USSR, the Marxist ideology is taken into account. The present paper continues the author’s previous analysis of ensemble interpretations which emerged in the USA and USSR in the first half of the 20th century. The author emphasizes that the ensemble approach turned out to be a dead end for the development of the interpretation of quantum mechanics in Russia. The article also argues that in Soviet Russia, the classical Copenhagen (standard) approach to quantum mechanics was used. The Copenhagen approach was developed by Lev Landau in 1919–1931 and became the basis of the Landau-Lifshitz famous course on quantum mechanics, one of the classics of twentieth-century physics literature (the first edition was published in 1947). Although Vladimir A. Fock’s approach to the interpretation of quantum mechanics differs from the standard presentation by Lev Landau and Evgeny Lifshitz, Fock put forward a very important principle that complementarity is a “firmly established law of nature”. The fundamental writings of Lev Landau, Vladimir Fock and Igor Tamm, the authors of the mid-twentieth century, did a lot to defend the standard point of view such as the popular interpretations by Landau and Lifshitz. This approach can be traced back to Landau’s early writings and to Fock’s criticism of the ensemble approach.

Guang-Liang Li

By revisiting two famous questions about the Copenhagen interpretation of quantum mechanics, this article presents a concise analysis of the quantum measurement problem concerning both microscopic and macroscopic objects. The method used here is mainly based on the concept ``isolated point'' in ``point-set topology''. The findings reported are as follows. (a) Einstein's argument has been misunderstood; he was opposed to the so-called ``inherently probabilistic nature of quantum mechanics'' in the Copenhagen interpretation rather than to the use of probability in quantum mechanics. (b) Probability used in Einstein's ensemble interpretation is identical to the quantum-mechanically calculated probability. (c) The wave-functions in Einstein's ensemble interpretation neither describe any single quantum object purportedly possessing mutually exclusive properties simultaneously when nobody looks nor collapse abruptly when an observer performs a measurement.