Karl Popper's forgotten role in the quantum debate at the edge between philosophy and physics in 1950s and 1960s

Abstract

It is not generally well known that the philosopher Karl Popper has been one of the foremost critics of the orthodox interpretation of quantum physics for about six decades. This paper reconstructs in detail most of Popper's activities on foundations of quantum mechanics (FQM) in the period of 1950s and 1960s, when his involvement in the community of quantum physicists became extensive and quite influential. Thanks to unpublished documents and correspondence, it is now possible to shed new light on Popper's central -though neglected-role in this "thought collective" of physicists concerned with FQM, and on the intellectual relationships that Popper established in this context with some of the protagonists of the debate over quantum physics (such as David Bohm, Alfed Landé and Henry Margenau, among many others). Foundations of quantum mechanics represented in those years also the initial ground for the embittering controversy between Popper and perhaps his most notable former student, Paul Feyerabend. I present here novel elements to further understand the origin of their troubled relationship.

"Philosophysics" at the University of Vienna: The (pre-)history of foundations of quantum physics in the Viennese cultural context

“…In the early 1980s, Vigier has also been the main influence on the over-80-years-old philosopher Karl Popper -who had been engaging with problems of FQM since 1934 and as such should be considered a fullyfledged "quantum dissident" [6]-to actively engage again with the community of quantum physicists. Indeed, at a conference in Bari, organised by Selleri himself, Popper presented a "simplified version of the EPR experiment", which by means of measurements on an entangled pair of particles supposedly would have discriminated between a realist interpretation and the Copenhagen one.…”

“…exception of a handful of "dissidents" (see Freire's comprehensive book [2], and [3][4][5][6][7][8] for specific case studies). At the same time, even non-military research projects turned into a collective enterprise that involved tens if not hundreds or thousands of physicists (the so-called big science) and it was predominantly oriented towards particle physics, characterised by the race to reach higher and higher energy scales in particle accelerators (such as the at that time newly founded CERN in Geneva).…”

“… Bell's theorem states that the predictions of quantum mechanics are incompatible with those of any local hidden variable theory 6. Although Pauli never studied physics nor worked in any university in Vienna, arguably the intellectual Viennese landscape had a major influence on his career.…”

An unpublished debate brought to light: Karl Popper's enterprise against the logic of quantum mechanics

“…On the one hand, it helps to shed light on the interplay between philosophers and physicists on the ground of foundations of QM, and in particular, on the peculiar role played by Popper at the edge between these communities (see further and cf. Del Santo, 2019). In particular, I will provide new evidence of his forgotten endeavour against the LQM (and the Copenhagen interpretation along with it), thanks to a number of new archival sources.…”

“…23(March 4 th , 1969. PA, 96/7).On May 8 th , 1969, the Argentinian philosopher and physicist Mario Bunge -who was already involved in Popper's campaign against LQM (see section 3.1 and DelSanto, 2019) and had helped him a great deal to engage with the community of physicists -discussed Popper's Nature paper with Scheibe, who showed a great interest (PA, 280/26). Scheibe wrote toPopper, on December 1 st , 1970,…”