Organized Session

History of Interpretations of Quantum Physics

Organizer

Gustavo Rodrigues Rocha

Universidade Estadual de Feira de Santana

Chair

Olival Freire

Universidade Federal da Bahia

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Session Abstract

The Nobel Prize winner Steven Weinberg surprised many by declaring: "I'm not as sure as I once was about the future of quantum mechanics." Weinberg's statement points in direction of a commonly perceived understanding nowadays that interpretations of quantum physics have become in late 20th century, once again, and for several different reasons, an appealing subject for mainstream physicists - as well as for philosophers.

If that holds true for physicists and working scientists, it certainly does for historians of science likewise. The controversies around the several contrasting interpretations of quantum physics are also appealing to historians of science because they draw together a plethora of factors related to concepts, experiments, instruments, philosophy, politics, ideology, cultural changes, and professional biases, among others.

It is thus a fascinating instantiation of the complexities of the workings of present science - in so many different levels and enticing nuances that it makes worthwhile even trying different approaches to shed lights on one single out of several interpretations.

Furthermore, it is not a linear history, but on the contrary, interpretations have been debated, and then forgotten, and then revived, over and over again, exposing, at each of these stages, some of these factors, themes, and many other historiographical issues.

In order to make the most of this session, we will bring together a variety of perspectives (as for localities, nationalities and research projects and concerns of each physicist approached by each speaker in this session by means of different proposals).

Presenter 1

The Foundations of Quantum Mechanics in Post-War Italy's Cultural Context

Flavio Del Santo

Faculty of Physics, University of Vienna

Abstract

After World War II, a hyper-pragmatic paradigm was established in physics, summarised by the expression "Shut up and Calculate!", and foundations of quantum mechanics (FQM) became vastly dismissed as pointless speculations.

In Italy at the turn of 1970s, however, an unprecedented critical mass of physicists revived the interest towards FQM. This was the initiative of a generation of young, radically politicized phys-icists (among whom stand the names of Franco Selleri, Marcello Cini, Angelo Baracca, Silvio Bergia and Giancarlo Ghirardi). They channeled the general political atmosphere of the 1968 left-wing struggles for dismantling the capitalistic society, yet within physics. The goals of this radical physicists were very ideological since they aimed at challenging the very contents of modern science, regarded as a product of the capitalistic society.

Quantum theory became the target of these unsatisfied young physicists who saw in the newly introduced Bell's Inequalities the tool to show its limits of validity, thus legitimizing their overall critique of science. These idiosyncratic aims provided the motivation for the beginning of a sys-tematic study on FQM that could have provided the opportunity for the introduction of a totally new physical framework.

Although most of these attempts eventually turned out to be unsuccessful (the experiments on Bell's theorem confirmed the predictions of quantum mechanics), these efforts opened a lasting period of intense research on FQM that involved tens of (Italian) physicists and helped pave the way towards a recognition of the FQM as a fully-fledged field of physics.

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Presenter 2

Rewriting the History of the Foundations of Quantum Mechanics: The Madame Wu Case

Indianara Lima Silva

Universidade Estadual de Feira de Santana

Abstract

Chien-Shiung Wu was one of the most remarkable experimental physicists in the 20th century. With her 1956 experiment, violating the parity in weak interactions, she entered the forefront of the American experimental physics. Wu was the first woman President of American Physical Society, received prestigious prizes from the scientific community, as The Wolf Prize and The National Medal of Science, and worked on affirmative actions for women's rights. Besides her contributions to nuclear physics and society, Wu also dedicated to the foundations of quantum mechanics at a time when this kind of research agenda was considered "not real physics" (Freire Jr, 2015). At Columbia University, she and her graduate student Leonard Kasday performed in 1974 an experiment to test the predictions of quantum theory to widely separated particles. Using Compton's scattering, they analyzed the coincidence rate of photons arriving over angles both polar and azimuthal. They concluded, "the distributions we observed could not give results allowed by Bell's theorem" and therefore their results disagreed with local hidden-variable theories (Kasday, Ullman and Wu, 1975, p. 633). This talk will revisit the history of the foundations of quantum mechanics to write a new chapter, considering, now, Madame Wu's contributions to the material culture that would lead the research in foundations to the status of mainstream physics. Besides, it will address how Wu and Kasday interpreted their experimental results in light of debates on the foundations of quantum mechanics.

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Presenter 3

David Bohm (1917-1992) - Biography of a Major Quantum Dissident

Olival Freire Junior

Universidade Federal da Bahia

Abstract

The emergence of the research on the foundations of quantum mechanics in the 20th century was a work of quantum dissidents, physicists who considered there was good physics to be done on this issue thus taking distance from the dominant view that foundational issues were already solved by the founding fathers. One may learn this process looking the biographies of these scientists. Notable among them was the American physicist David Bohm. Student of Oppenheimer, considered among the promising American physicists after the WWII, he was targeted by the McCarthyism and left the US forever, living successively in Brazil, Israel, and the UK. Before this he had gotten a bug, interest in the foundations of quantum mechanics, which would not leave him. In fact, his first work was a textbook, Quantum Theory (1951), intended to be a realistic view of what he called the quantum world, along the lines thought by Niels Bohr. He moved then to an alternative interpretation, called hidden variables or causal interpretation, which was criticized by most and supported by a few ones. Till the end of his days, he kept himself reflecting about the quantum world, the quantum physics, and its lessons for the future of science, though much of these later investigations were too abstract and left few followers. In addition, Bohm left enduring contributions for the study of plasma and quantum effects such as the Aharonov-Bohm effect. Thus, he was a great physicist and his quantum dissidence was part of his achievements.

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Presenter 4

A Brief Historical Perspective on the Consistent Histories Interpretation of Quantum Mechanics

Gustavo Rodrigues Rocha

Universidade Estadual de Feira de Santana

Abstract

I will outline in this talk a historical account of the consistent histories interpretation of quantum mechanics based on primary and secondary literature, archival research (such as the Caltech Archives) and interviews (made by myself and others).

I shall begin this talk by tracing the motives behind Robert Griffiths' seminal 1984 paper, Consistent Histories and the Interpretation of Quantum Mechanics, the first physicist to have proposed a consistent-histories interpretation of quantum mechanics.

I will then follow Omnès' 1990 paper, From Hilbert Space to Common Sense: A Synthesis of Recent Progress in the Interpretation of Quantum Mechanics, to bring to light how Omnès came to his own interpretation and understanding - seen by him as a "progress" over Griffiths' -, meaning, a consistent histories model based on Boolean logic, whereas the mathematical framework remains basically identical.

Murray Gell-Mann and James Hartle's steps to their own version of consistent-histories approach, motivated by a cosmological perspective, will then be described and evaluated. Gell-Mann and Hartle understood that spontaneous decoherence could path the way to a concrete physical model to Griffiths' consistent histories.

Moreover, the collective biography of these figures will be put in the context of the role played by the Santa Fe Institute, co-founded by Gell-Mann in 1984 in Santa Fe, New Mexico, where Hartle is also a member of the external faculty (and where both of them worked together back in the early 1990s).

Finally, I want to compare and contrast these proponents of the consistent histories interpretation of quantum mechanics with their most prominent critics (such as d'Espagnat, Giancarlo Ghirardi, Basil Hiley, Adrian Kent, Euan Squires, Angelo Bassi and Fay Dowker).

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