Schrödinger’s Version of EPR, and its Problems

Jos Uffink

Guido Bacciagaluppi, Elise Crull

This chapter details not only the prehistory of EPR but also examines the structure and logic of the EPR paper – including Einstein’s own preferred version of the argument for incompleteness. We here attempt a seamless interweaving of the excellent extant literature with additional details that have emerged from our work and the recent work of others. Some examples of new aspects in this prehistory of EPR include evidence of a ‘proto’ photon-box thought experiment Einstein had developed in connection with his ill-starred collaboration with Emil Rupp in 1926. We also describe the potential importance to this prehistory of Einstein’s paper with Tolman and Podolsky and of Einstein’s seminar and discussions with Schrödinger in Berlin in the early 1930s.

Michael Dickson

Filippo Maimone, Giovanni Scelza, Adele Naddeo

Abstract It is explicitly shown that a one-family parameter model reproducing the nonlinear Newton–Schrödinger equation as the parameter goes to infinity is free from any causality violation problem for any finite value of it. This circumstance arises from the intrinsic mechanism of spontaneous state reduction of the model, absent in the Newton–Schrödinger limit. A specific ideal EPR experiment involving a superposition of two distinct CM’s position states of a massive lump is analyzed, showing recovered compatibility with quantum mechanics. Besides, the new framework suggests a soft version of the many worlds interpretation, in which the typical indiscriminate proliferation of Everett branches, together with the bizarre inter-branches communications made possible by nonlinearity, are strongly suppressed in the macroscopic world by the same mechanism of state reduction.

Mara Beller, Arthur I. Fine

Charles P. Tresser

Two typical entanglements will be shown to stand on opposite sides on the issue of \emph{instrumental realism}, the issue of whether (as for EPR in the original form or EPRB, Bohm's versions using spin) or not (as for GHZ) observables have values that preexist measurement. Instrumental realism in the EPR context helps us prove that in some special circumstances, one can get simultaneous knowledge of two conjugate quantities, which in particular make sense together. This shatters the axiomatic presentation of Quantum Mechanics. This simultaneous knowledge of two conjugate quantities elaborates on 1935 work by Schr{ö}dinger, hence the name, \emph{Schr{ö}dinger Unorthodoxy Theorem}, given to the second main result that is easily deduced from the result on instrumental realism. Once the axiomatic edifice of Quantum Mechanics is broken, we can let go the completeness of the wave function as suggested in EPR, and hold fast on locality. The EPR paper of mid-1935 gets here contrasted, from a new point of view, with a 1936 text where Einstein avoids using counterfactuals. Counterfactuals get a precise definition and the corresponding concept is used all along, but may be new under an old name. We provide a short critical review of Bell's 1964 paper. Then, a small modification of arguments for the Schr{ö}dinger Unorthodoxy Theorem will let appear a simple conservation law, combined with the Malus Law, as the origin of the correlation in Bell's version of EPRB: this is our third main result. As the fourth main result, a last use of the concept of counterfactual yields the decay of geometry at small enough scale. This opens a new world of interpretation of aspects of Quantum Mechanics, aspects that range from measurement and the need of classical physics to views on what realism should mean in microphysics.