BOHR'S COMMENTARY ON THE EPR-PAPER

BOHR, N.

Quantum Mechanics and Physical Reality.

London, Macmillan & Co., 1935.

Royal8vo. Bound in contemporary half cloth with paper title label to spine. In "Nature", Vol. 136, July - December, 1935. Stamp to first two leaves. Light wear to spine, otherwise a nice and clean copy. P. 65. [Entire volume offered: LXVIII, 1040 pp.]. 

First appearance of Bohr's short comment on Einstein, Podolsky and Rosen's famous paper (The EPR-paper), which "created a stir among physisists and has played a large role in philosophical discussion"(Bohr). The paper stated an ontological and epistemological incompleteness in Quantum Physics and postulated that a causal description of all physical phenomena must be possible.

"The three authors started by stating that physical concepts must corresponds to aspects of physical reality. Their reality criterion was this: "If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of physical quantity, then there exists an element of physical reality corresponding to this physical quantity." The correspondence led to a necessary condition for the completeness of a physical theory, namely, "Every element of the physical reality must have a counterpart in the physical theory." Einstein, Podolsky, and Rosen (EPR) now argued that quantum mechanics combined with the reality criterion led to a contradiction and that the only alternative was to accept that a quantum mechanical decription of reality id not complete.... Bohr was greatly disturbed by the EPR argument asnd started at once to develop a counterargument, which he had ready after a period of about five months... His main line of argument was a rejection of the criterion of physical reality proposed by Einstein, Podolsky, and Rosen..." (Helge Kragh "Quantum Generations", pp. 215 ff.).- Schrödinger developed his own argument in favour of the EPR positions and against Bohr ("Schrödinger's Cat"- argument).

Wolfgang Pauli wrote Heisenberg a long and angry letter. "Einstein has once again expressed himself publicly on quantum mechanics (together with Podolsky and Rosen - no good company, by the way... (and) "As is well known, every time that happens it is a catastropphe."

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