Towards a Quantum Culture: The Different Interpretations of Quantum Mechanics

9 Dec 2025, 09:00 → 11 Dec 2025, 13:30 Europe/Rome

Towards a Quantum Culture: The Different Interpretations of Quantum Mechanics

A Workshop of the Italian Society for the History of Physics and Astronomy to celebrate the 100th anniversary of the establishment of quantum mechanics (1925)

University of Milano, Department of Physics

9-11 December 2025

The Workshop

The Meeting is related to the celebration of the rise of quantum mechanics in 1925. It aims to promote research in the history of physics and astronomy in Italy, carried out by academic historians, independent scholars and school teachers interested to explore the role of the history of these disciplines in contemporary science education. At the same time, the Meeting provides an opportunity to strengthen existing collaborations and establish new connections among SISFA members, other scholarly societies, and researchers working in related fields.

Historians of physics and astronomy are invited to participate, and the invitation is extended to all scholars and researchers with similar interests.

Topics

Proposals for oral communications should mainly address the history of quantum physics and cosmology, also in connection with the related areas of mathematics, chemistry, biology, neurobiology, information theory, epistemology and the history of science and culture. Studies focusing on historical instruments and experiments and documentary sources regarding the mentioned fields are also relevant to the purposes of the Conference, as well as the applications of the history of physics and cosmology in science education and museum displays.

Thematic sessions:

• Quantum Culture
• Different Interpretations of Quantum Mechanics
• Different Formulations of Quantum Mechanics
• Old Quantum Physics and Quantum Mechanics
• Quantum Mechanics and Quantum Relativistic Field Theory
• Quantum Gravity and Quantum Cosmology
• Quantum Biology and Quantum Neurobiology
• Quantum Information and Computation
• Quantum Logic 

Registration and abstract submission

Registration is mandatory to attend the conference. There will not be any conference fee.

Abstracts of oral communications should be submitted in English at workshop@sisfa.org.

All abstracts will be peer-reviewed on behalf of the SISFA scientific committee. Please see below for more details regarding important dates, abstract submission and registration.

Tuesday 9 December

13:00 → 14:00 Registration

14:00 → 14:30 Opening cerimony and institutional welcome

14:30 → 15:50 Quantum mechanics

Convener: Leonardo Gariboldi

14:30 The Transforming Force of Mathematics: From Quantum Jumps to Quantum Mechanics to Quantum Culture, with Werner Heisenberg

Shortly before his discovery of QM was published, Werner Heisenberg said in his letter to Ralph Kronig: “What I really like in this scheme is that one can really reduce all interactions between atoms and the external world to transition probabilities.” This statement reflects a revolutionary transformation—physical, mathematical, and philosophical—that Heisenberg’s theory brought with it. First and foremost, one needed a theory that could predict these probabilities. The invention of this theory, QM, was Heisenberg’s greatest invention, and the driving force, mathematical in nature, of this revolution. His invention could be compared the invention of the mathematics of classical physics by Descartes, Galileo, and, especially calculus, by Newton, in the emergence of the new culture of their own time, the culture of modernity as a mathematical and scientific culture. QM brought the role of mathematics in physics to a new level and initiated a new epoch of the relationships among mathematics, physics, philosophy, and culture, by making quantum culture part of our culture. Our culture is still coming to terms with quantum culture, in part because the resistance to it, not the least by physicists and philosophers, have been strong and never subsided. By contrast, I shall suggest, modernist literature and art, such as Joyce’s novels and Kandinsky’s abstract painting, made thinking akin to that of Heisenberg leading to QM a creative force of literature and art, and played key roles in advancing quantum culture.

Speaker: Plotnitsky Arkady

15:10 Heisenberg’s 1925 Paper and the Need for a Reinterpretation of the Concept of Trajectory

In the abstract of his “Umdeutung” paper—traditionally regarded as the founding act of quantum mechanics—Heisenberg declares that the purpose of his work “is to attempt to establish the foundations for a quantum-theoretical mechanics that is based exclusively on relationships between quantities that are, in principle, observable”. This statement has often drawn readers’ attention to the philosophical aspects of Heisenberg’s approach. However, after having noted that the trajectory of an electron within an atom is not observable, Heisenberg proceeds—on the basis of precise physical and mathematical arguments—to show the impossibility of identifying a classical trajectory capable of generating the observed electromagnetic spectrum. This reflection marks the beginning of the “reinterpretation” announced in the title of the paper and forms the basis of his new formulation of quantum theory. Thus, the need to reinterpret the concept of trajectory, as indicated in the title itself, is not for Heisenberg merely or primarily a philosophical issue (inspired by positivism), but rather an essential element of the emerging theory. The nonexistence of a well-defined trajectory would continue to concern Heisenberg and ultimately lead him to formulate the uncertainty principle in 1927—although in that later context the argument is extended to show the general impossibility of defining a trajectory in quantum mechanics. Heisenberg’s early “philosophy”, therefore, seems mainly grounded in profoundly physical considerations. In this presentation, we will focus on this important aspect of the 1925 paper, which, in our view, has often been insufficiently appreciated and discussed.

Speakers: Marco Giliberti, Luisa Lovisetti

15:50 → 16:20 Commemoration

Convener: Enrico Giannetto

15:50 Commemoration “In memory of Francesco Guerra

16:20 → 16:50 Coffee break

16:50 → 17:50 Communications I

Convener: Matteo Leone

16:50 E(p/in)stein & Quantum Theory Around 1917

We’re in the phase of the old quantum theory that begins—after Sommerfeld’s refinements (1915) to Bohr’s atom—to involve sophisticated analytical mechanics; Schwarzschild (1916) has just turned atomic mechanics into a Hamiltonian ‘micro-celestial’ mechanics, with action-angle variables, resonances etc. The two names in my title represent the two research programmes I propose to compare. On the one hand there’s Einstein on his own, with three texts from his annus mechanicus 1917—but mainly “Zum Quantensatz von Sommerfeld and Epstein”; whereas “Epstein” stands for what I’m considering the ‘other research programme,’ which in addition to Paul Epstein himself involved his teacher Sommerfeld, Schwarzschild &al. Both programmes (Einp stein) involve ancestors of the invariant tori that emerge decades later—developing them in very different ways: Einstein through his Riemannisierung, Epstein through canonical action-angle variables. Whereas Epstein have a quantum condition for every (angle) coordinate, Einstein proposes a highly invariant theory with a condition for every homotopy class of the N-torus. Each of his quantum conditions is doubly invariant: with respect to loop deformations, and to coordinate transformations. Epstein use perturbations to obtain as much ‘ergodicity’ as possible—the more the better; whereas Einstein needs some but not too much—which would render his Riemannisierung inapplicable.

Speaker: Alexander Afriat

17:10 Doubling a Quantum Process: the Intriguing History of a Rare Process

Just ten years since the introduction of quantum mechanics, and soon after the appearance of the Fermi’s theory of beta decay, an elusive and intriguing process was theoretically introduced in the realm of nuclear physics by “doubling” known decays. We here reconstruct the genesis and the early history of such a process, starting from Maria-Goeppert Mayer’s Ph.D. work on the theory of processes characterized by the emission or the absorption of two photons. A detailed analysis of her seminal 1935 paper, describing the so-called 2-neutrino double beta decay, is carried out, along with a discussion of several issues related to the later introduction in 1937 of Majorana’s neutrino picture. Finally, we deal with the neutrinoless version of double beta decay, whose existence was put forward by W.H. Furry in 1939, and later served to assess the true nature of the (still today) elusive neutrino.

Speaker: Adele Naddeo

17:30 The Long Historical Path Towards the Logic of Quantum Mechanics

We historically retrace the path towards the construction of a logic for quantum mechanics, starting from the analysis of J. von Neumann’s seminal contributions, which include his work with G. Birkhoff on quantum logic, and his first paper on operator algebras with F. J. Murray. The emerging feature is his growing dissatisfaction with the Hilbert space formalism, because of the ensuing infinite and not a priori normalizable quantum probability, which led him to look for a new mathematical structure for quantum logic, later identified with the modular projection lattice of the type II1 factor. These works generated a wide debate; after critically analysing the main contributions to it, we concentrate on a more recent proposal by A. Drago and A. Venezia, who suggested that the sought for logic is intuitionist logic. Their proof was limited to the examination of the uncertainty relations, which have been considered by von Neumann in a second time; hence, it did not address the full quantum theory. Later, G. Morchio and F. Strocchi rigorously formalized Dirac’s formulation of quantum mechanics using C*-algebras. This allows reformulating the theory as a problem-based theory whose aim is to solve the problem of the relationship between classical mechanics and quantum theory; in turn, the problem is solved by making use of doubly negated propositions and ad absurdum proofs, allowing to argue that the underlying logic is the intuitionist one, and fully realizing Drago and Venezia’s proposal. The analysis of Morchio and Strocchi’s work ends our reconstruction.

Speaker: Marco Di Mauro

17:50 → 18:50 Communications II

Convener: Matteo Leone

17:50 David Bohm’s Interpretation of Quantum Mechanics

David Bohm is known for proposing a philosophical interpretation of quantum mechanics that reintroduces the concept of so-called hidden variables. His 1952 formulation faced significant criticism, one of many because of the theory's inherent nonlocality. However, later developments in theoretical physics—especially the formulation of Bell's inequalities—may have lessened these objections by showing that nonlocality is an intrinsic property of quantum phenomena. Less recognised, though, is Bohm's attribution of physical meaning to the magnetic vector potential in quantum theory, which he expressed in 1959 through the Aharonov–Bohm effect thought experiment.

Speaker: Luisa Spairani

18:10 From Madelung to Bohm

Bohm's interpretation of Quantum Mechanics presents similarities and analogies with other previous models, of which it represents an evolution. A direct comparison between the various models allows us to better understand the meaning of Bohm's formulation and demonstrates the importance of interpretation in understanding physical theories characterized by the same mathematical formalism. The starting point can be identified with the hydrodynamic model of E. Madelung, published in 1927. According to this model, the Schrödinger equation describes an ideal, viscous "fluid" composed of identical particles (electrons) of mass m and electric charge -e. In 1928 Earle H. Kennard proposed a purely quantum interpretation of the same equations obtained by Madelung, introducing the concept of quantum potential, which will also be used by David Bohm. De Broglie pilot-wave theory takes up the formalism common to previous formulations, but offers a still different interpretation. The realist interpretation of the particle and the wave that drives it through the de Broglie guiding condition is the defining feature of his theory. Bohm's work bears strong similarities to that of de Broglie, from which it is explicitly derived. The innovative idea introduced by Bohm consists in assigning to the particle an initial position r_o (hidden variable) and a velocity v = ∇ S/m, so that the particle's trajectory would be uniquely defined, if only the initial position could be known. On Louis de Broglie‘s use of unified field theory in his quest for causality and realism in quantum physics.

Speaker: Gianluca Introzzi

18:30 Against the ‘Nightmare of a Mechanically Determined Universe’: Why Bohm was Never a Bohmian

David Bohm has put forward the first deterministic interpretation of quantum physics, and for this he seems to be regarded as a champion of determinism by physicists (both his contemporaries and the supporters of his interpretation, the so-called "Bohmians") as well as by historians of physics. The standard narrative is that he underwent a "conversion" from being a supporter of Bohr to being a staunch determinist, due to his interaction with Einstein and his commitment to Marxism. Here we show that Bohm actually upheld with continuity throughout his career some philosophical tenets that included a strong rejection of mechanistic determinism. As such, we conclude that Bohm was never a Bohmian and that his philosophical views have been largely misinterpreted.

Speaker: Flavio Del Santo

Wednesday 10 December

09:00 → 10:20 Quantum mechanics

Convener: Enrico Giannetto

09:00 Quantum Mechanics, the Universe, and the Multiverse

Traditionally considered a theory only of the subatomic domain, quantum mechanics entered cosmology in 1931 with G. Lemaître’s primeval-atom hypothesis. Much later, theories based on quantum gravity, such as string theory and loop quantum gravity, have been developed into cosmological models. Moreover, quantum-based theories of multiple universes have recently attracted much attention. Modern hypotheses of the multiverse are in part justified by the many-worlds interpretation of quantum mechanics which according to some physicists is the only correct interpretation. Apart from outlining the historical background for the role of quantum mechanics in cosmological thinking, the presentation will focus on the multiverse and related hypotheses in which quantum mechanics play a crucial role. Is ‘quantum cosmology’ more than just a label? By critically looking at the fate of this diverse class of theories, some general comments will be offered on the current status of the standard cosmological model (ΛCDM) and its possible alternatives.

Speaker: Helge Kragh

09:40 Interpreting Quantum Mechanics Relationally

The relational interpretations of quantum mechanics, started in the late 1990's, are suddenly receiving a great deal of attention in the literature. I review the basic ideas, the problems raised, the variants and the current status of this way of looking at quantum theory, which offers a coherent picture of the quantum world without hidden variables, without many worlds, without physical collapse, and without giving a privileged role to betting agents. I will focus on the peculiar philosophical position of these interpretations, which keep themselves away from both a naive form of realism and from instrumentalism.

Speaker: Carlo Rovelli

10:20 → 10:50 Coffee break

10:50 → 12:10 Quantum mechanics

Convener: Nadia Robotti

10:50 Enigmas of the sp^hin^x

Beyond the well-known epistemological and foundational problems of quantum theory (measurement theory, entanglement, classical limit, etc.), there are others conceptual questions which have been somewhat neglected in the past decades.
I will discuss five of these open questions, all connected with the notion of spin:
‐ the puzzle of the intrinsic magnetic moment
‐ the spin-forces connexion
‐ the spin-statistics connexion
‐ the spin-charges connexion
‐ the mystery of spin renormalization

Speaker: Jean-Marc Lévy-Leblond

11:30 The Long Quantum Revolution

The talk will review different phases of the quantum revolution with an emphasis on critical developments in the 1920s and the 1950s. On the basis of joint work in the context of the quantum project of the Max Planck Institute for the History of Science it will be shown how the exploration of the limits of classical physics yielded results that served as the scaffolding for the first quantum revolution of the 1920s. The talk will further argue that the second quantum revolution associated with the work of Clauser, Aspect, and Zeilinger goes back to the challenges to the Copenhagen interpretation by quantum dissidents like David Bohm.

Speaker: Jürgen Renn

12:10 → 13:10 Communications III - Quantum physics and quantum mechanics in Italy

Convener: Ivana Gambaro

12:10 Italian Physicists and Old Quantum Mechanics: the Case of Antonio Garbasso and Antonino Lo Surdo

As part of a project by the Italian Physical Society (SIF), inspired by the centenary of quantum mechanics and the International Year of Quantum Science and Technology (IYQ), this talk will revisit the work of Italian physicists Antonio Garbasso and Antonino Lo Surdo, who are credited with introducing quantum mechanics to Italy. In late 1913, Garbasso adopted Bohr’s 1913 theory of atomic structure to explain the recently discovered effect of electric fields on spectral lines– an effect discovered independently by Johannes Stark and Antonino Lo Surdo. This effect, which represents an interesting case study of both an almost simultaneous experimental discovery and an independent theoretical interpretation of the same phenomenon, became known as the "Stark effect", but in Italy it was often referred to as the "Stark-Lo Surdo phenomenon". In this talk, we will address both the experimental and theoretical aspects of this case study. On the experimental side, we will compare the different approaches adopted by Lo Surdo and Stark and the results they obtained, with particular emphasis on Lo Surdo’s discovery of the differing behaviour of spectral lines within the same series. On the theoretical side, we will compare the formulations proposed by Garbasso and Bohr to explain this quantum effect, highlighting similarities and differences.

Speakers: Matteo Leone, Nadia Robotti

12:30 The Arrival and First Developments of Quantum Mechanics in Milan

This paper presents Aldo Pontremoli's introduction of matrix mechanics and wave mechanics into advanced physics teaching at the University of Milan and the developments of quantum mechanics by Giovanni Gentile Jr. Trained by Corbino and Rutherford, Pontremoli introduced the new quantum theories into his teaching and was the first professor of Theoretical Physics, being among the winning trio of the first Italian public competition together with Fermi and Persico. Pontremolì's successor as professor of Theoretical Physics in Milan was Giovanni Gentile Jr. At Polvani's suggestion, he addressed the topic of intermediate statistics, that is, quantum physical systems with occupation numbers intermediate between one (Fermi-Dirac statistics) and infinity (Bose-Einstein statistics).

Speaker: Leonardo Gariboldi

12:50 Quantum Foundations and the Milan School: A Historical and Conceptual Perspective

The Department of Physics at the University of Milan has long shown a strong commitment to the conceptual and formal development of quantum mechanics, both in research and in teaching. A clear indication of this attention is that, as early as the 1926–1927 academic year, a series of lectures was delivered by A. Pontremoli—then Professor of Theoretical Physics—explicitly devoted to matrix and wave mechanics, making Milan one of the first Italian universities to include quantum mechanics in its curriculum. From the late 1950s onward, foundational aspects of quantum theory began to attract particular interest among several faculty members. Among them, G.M. Prosperi (1931–2025) stands out for his significant contributions, most notably the 1962 paper Quantum Theory of Measurement and Ergodicity Conditions, co-authored with A. Daneri and A. Loinger. As the title suggests, the paper addresses the quantum measurement problem—widely debated between the early 1930s and late 1950s—reinterpreted through the conceptual framework proposed by Jordan and Ludwig. The Milan group devoted several years to establishing a formal basis for this conjecture using tools from quantum statistical mechanics. The paper, still cited today, had a major impact at the time and was discussed by leading physicists such as Wigner, Bohm, and Rosenfeld, as well as by historians and philosophers of science. The aim of this presentation is to illustrate the aforementioned aspects, with particular emphasis on the scientific legacy of Prosperi.

Speakers: Luisa Lovisetti, Marco Giliberti

13:10 → 15:00 Lunch

15:00 → 16:20 Quantum mechanics

Convener: Luisa Lovisetti

15:00 Constructivism and the Foundations of Quantum Mechanics

In the last decades, various efforts have been made in reconstructing the mathematical language of quantum theory from operational axioms. We will propose a perspective on the meaning of such results, highlighting their development that lead to a reconstruction of mechanical notions in a purely information-theoretic framework. We will argue in praise of a constructivist view on the underpinnings of quantum physics as the less metaphysically committed route to foundations left open after the experimental violations of Bell's inequalities. Consequently, we will invoke the introduction of measurement on the same fundamental footing as the laws of evolution of isolated systems

Speaker: Paolo Perinotti

15:40 Perspectives on Recent Developments of de Broglie’s Realistic and Bohr’s Complementary Interpretation of the Wave-Particle Duality

Speaker: Gino Tarozzi

16:20 → 16:50 Coffee break

16:50 → 18:10 Quantum mechanics

Convener: Salvatore Esposito

16:50 Pauli’s Interpretation of Quantum Physics

Wolfgang Pauli developed an original interpretation of quantum mechanics in terms of Bohr’s correspondence principle as an ontological texture of physical reality and complementarity principle as a generalization of the correspondence principle. Following Pauli, there is an a-causal connection, a statistical correspondence (non-separability/ “synchronicity”) between quantum microcosm and (human) macrocosm. This kind of non-mechanistic conception of Nature as well as the idea of non-separability of the world and of synchronicity, as stated by Carl Gustav Jung itself, was firstly developed by Leibnitz: from this point of view, we can look at quantum physics (as well as for relativity it was shown) as related to a new emergence of concepts belonging to the Leibnitzian (anti-Newtonian) tradition. By a historical analysis of Kepler’s works and of part of the so-called ‘scientific revolution’, Pauli has started to show that physical theories and the related ‘mental representations’ could have their roots in archetypical images of the collective unconscious which have been investigated by Carl Gustav Jung. For example, there were geometrical archetypical images which could have determined the mental representations and the cosmological and physical theories of space, time and Nature. Modern physics is not only a rational mathematical construction, but above all is a fruit of a scientific epistemology of imagination. Thus, Pauli suggested not only a new physical, philosophical and historical interpretation, but also a very original psychoanalytic interpretation of quantum physics in terms of collective unconscious’ archetypal images and considered it as a new kind of alchemy, which recovered the removed unity of Psyché and Physis and implied the unity of the whole field of knowledge and of Eastern and Western traditions, and led to an ethical transformation of mankind in front of a re-enchantment of Nature.

Speaker: Enrico Giannetto

17:30 Quantum Theory and the Two Foundational Dichotomies

Six independent programs of research have led to recognize two dichotomies as the foundations of Physics: one on the kind of infinity, potential or actual, another on the kind of theoretical organization, problem-oriented or deductive-axiomatic. In 1930, first Dirac formulated quantum theory. Contrary to popular belief it was a problem-oriented theory and its mathematics was algebraic, hence essentially referring to the mathematics of only potential infinity. Hence its basic choices were opposite of Newton mechanics’ ones (deductive organization and actual infinity). But it was based on a naive analogy (between the commutators and the Poisson brackets of the Hamiltonian of the system). The subsequent formulation (von Neumann 1932) was accepted as the definitive theory. It uses the Hilbert space of functions based on actual infinity and its organization is deductive. Hence, this formulation reaffirmed the fundamental choices of Newton’s mechanics. Unsurprisingly, by overshadowing Dirac’s formulation, it became the new paradigm of theoretical physics, although its author, after writing his book, “confessed” to disbelieve in Hilbert space as the suitable mathematics for quantum theory. In 2008, Morchio and Strocchi provided, within a C*-algebra, a mathematical connection between commutators and Poisson brackets. Thus, Dirac-Morchio-Strocchi’s formulation (whose problem is which is the Hamiltonian of a physical system?) formally departed from Newtonian paradigm and constitutes the alternative to von Neumann’s formulation. Finally, the hidden variables of quantum theory have been recognized; however, they are at not the physical level but the scientific-philosophical level: the two dichotomies, which the author of a theory must determined through choices.

Speaker: Antonino Drago

18:10 → 19:10 Communications IV

Convener: Marco Giliberti

18:10 Conceiving Light: How Bohr’s Epistemic Framing of Light Linked Chemistry, Phototherapy, Ophthalmology, and Quantum Mechanics in 192-1932

Five years after introducing his ‘complementarity’ concept in 1927, Niels Bohr gave an unexpected address at the International Congress on Light Therapy titled ‘Light and Life’. In the lecture, Bohr used the concept of light to bridge new knowledge from quantum physics with the life-sciences, and noted that “light is our principal tool for observation.” What led Bohr to present an interdisciplinary analysis of light to a group of dermatologists? And how did he use light as an epistemological tool in his philosophy of quantum mechanics? This epistemological framing of light is a crucial, yet unresearched, key in Bohr’s philosophy. While the impact of Bohr’s lecture has been researched by historians, such as its influence on Delbrück’s biological research, there is no account of its genesis. Studies of Bohr’s interest in biology rarely examine interdisciplinary activities at his institute in the 1920s. Using drafts and letters from the Bohr archive, this talk points to the significance of several Danish chemists, dermatologists, ophthalmologists, and surgeons in Bohr’s intellectual circle, many working at his Institute during the emergence of quantum theory in two ways: first, this cohort of peers contributed to Bohr’s philosophical turn to biology in the late 1920s. Second, the group’s discussed ideas migrated into foundational concepts in Bohr’s philosophy, explaining what he called “the epistemological lesson of quantum mechanics”. These include clarifying biology’s influence on complementarity, distinguishing mechanical vs. quantum concepts, using the organism as a metaphor for open and closed systems, and exploring the object/subject distinction in observation.

Speaker: Mor Lumbroso

18:30 From ‘It from Bit’ to Relational Quantum Mechanics: Wheeler and Rovelli in Historical and Conceptual Perspective

The late twentieth century witnessed a profound reorientation in the conceptual foundations of physics, driven by renewed attention to questions of information, observation, and the nature of physical reality. At the heart of this transformation stand two figures whose work, though developed in distinct contexts and with different motivations, converges on a shared insight: that physical systems cannot be fully described in isolation, but only through their relations. John Archibald Wheeler’s proposal of a “participatory universe” and Carlo Rovelli’s formulation of Relational Quantum Mechanics (RQM) each offer radical reconfigurations of quantum theory, grounded in a reconceptualization of information as a physical and relational entity. This talk compares John A. Wheeler’s “participatory universe” and Carlo Rovelli’s Relational Quantum Mechanics (RQM), highlighting their shared emphasis on interaction and information. Though emerging from distinct contexts—Wheeler from cosmology and cybernetics, Rovelli from quantum gravity—both interpretations reflect a broader shift in late twentiethcentury physics toward relational and information-based ontologies. We trace their intellectual backgrounds and argue that each redefines physical reality not in terms of intrinsic properties, but through interaction and informational correlation. Finally, we suggest that developments in black hole physics and quantum gravity have served as a common testing ground, where foundational questions in quantum mechanics are reinterpreted through the lens of relational structure.

Speaker: Niccolò Covoni

18:50 John Wheeler's Quantum Ecumenism: From Niels Bohr to the Cosmological ‘It from Bit’

In the early 1970s, following the crisis of the geometrodynamical view of the cosmos inspired by general relativity, John Wheeler (1911-2008) suggested a few provocative ideas about the role of the observer or, as he called it, the "observer-participator". While this notion has often been portrayed as a radicalization, or perhaps an ontologization, of Bohr's views, its genesis was actually fostered by very different considerations, in part even cosmological. Moreover, in that same decade Wheeler, as shown by his archival papers, was exploring different facets of quantum physics, quite apart from the alleged "Copenhagen orthodoxy". These explorations, and their intertwinement with general relativity and cosmology, would later flow into the grand vision labeled with the famous - and often misunderstood - slogan “it from bit”. In this contribution, we will document how, throughout the 1970s, Wheeler’s views about the role the observer in quantum physics underwent subtle metamorphoses, becoming more and more de-anthropomorphized, and how this was related to the pressing question that Wheeler repeated until the end of his long life: "How come the quantum?"

Speaker: Stefano Furlan

Thursday 11 December

09:00 → 09:40 Quantum mechanics

Convener: Enrico Giannetto

09:00 Fermi, Majorana and the First Developments of the New Quantum Theory in Italy

The introduction of the novel quantum theory in Italy was mainly due to the work of Enrico Fermi, and the Roman school that developed around him between the end of the 1920s and the 1930s produced remarkable results both on the experimental and theoretical side. Especially Fermi and his former “student” Ettore Majorana contributed significantly to showing how the newly born quantum mechanics could be successfully applied in atomic, molecular and nuclear physics. Furthermore, they were able to introduce new concepts and new theories (or even just strengthen and clarify some of them, already introduced) that still represent milestones in the development of the quantum theory. In the present talk, just these contributions will be briefly discussed, revealing how fundamental results emerged in Italy during the 1930s both in the general quantum theory and its applications.

Speaker: Salvatore Esposito

09:40 → 10:20 Communications V

Convener: Enrico Giannetto

10:00 Between Political Orthodoxy and Personal Conviction: Terletsky’s Role in the Debate on Quantum Mechanics

In the 1950s, a heated debate unfolded in the USSR regarding the philosophy of quantum mechanics. Yakov Petrovich Terletsky, a professor of theoretical physics at Moscow State University and a member of the local bureau of the Communist Party, actively participated in this debate, questioning the Copenhagen interpretation and the principle of complementarity. His critique had significant influence, and many—from contemporaries to later commentators—interpreted his writings as a defense of party ideology and support for Blokhintsev’s ensemble interpretation, which at that time was seen as most compatible with dialectical materialism. Nevertheless, Terletsky personally advocated a realistic conception of the wave function and a causal interpretation of quantum mechanics. This position became clearer when he engaged with the de Broglie-Bohm theory through the mediation of Vigier. Amid the Cold War, he traveled to Paris to meet de Broglie and Vigier, with whom he collaborated on two articles. He also edited the Russian publication of Bohm’s papers, together with Hungarian physicists Fényes and Janossy, among others. In subsequent works, he continued to challenge the Copenhagen interpretation while promoting an objective, causal view of quantum mechanics. Later on, when most Soviet voices had shifted toward supporting complementarity, he publicly endorsed the de Broglie-Bohm-Vigier interpretation at an All-Union conference, confronting ideological prejudices against alternative interpretations. This study examines Terletsky’s role in the debate, aiming to rebut the misconception that he was merely a watchdog of ideological orthodoxy.

Speaker: Andrea Battocchio

10:20 → 10:50 Coffee break

10:50 → 12:10 Communications VI

Convener: Luisa Lovisetti

10:50 A Quite Elusive Century/Birthday: the 100th Anniversary of Quantum Mechanics, its Achievements and Criticalities, with a Case Study: Franco Selleri and his Philosophical and Sociopolitical Critical Standpoint

In the International Year of Quantum Science and Technology, this contribution introduces the different interpretations of quantum phenomena that have followed one another since 1900, together with the long debate that followed 1925, the annus mirabilis in which Quantum Mechanics was introduced, a powerful theory with numerous successes and multiple technological applications in our lives; but with lots of ambiguous aspects from a philosophical point of view. A case study was also analysed, expounding the critical approach of the Italian physicist Franco Selleri (1936-2013), based on philosophical and sociopolitical grounds.

Speaker: Luigi Romano

11:10 A Conceptual–Epistemological Account for a ‘Quantum Culture’

Discussions of the Second Quantum Revolution are frequently framed in terms of technological development, standards, and workforce training. This contribution adopts a different perspective: it presents the Quantum Revolutions (QRs) as conceptual and epistemological revolutions that are reshaping the way physical knowledge is conceived, represented, and communicated. The presentation analyses the First and Second QRs through a compare-and-contrast approach. It is used to investigate the core concepts (respectively complementarity and entanglement) that represented, first of all, conceptual and epistemological challenges and, then, turned into experimental challenges. Drawing on Aspect, both concepts were first conceived through thought experiments in the Bohr-Einstein debates: the complementarity around the nature of the quantum object, and the entanglement around the completeness of quantum theory. These conceptual and epistemological challenges became experimental ones: the double-slit experiment and the violation of Bell’s inequalities experiments. The compare-and-contrast approach was also applied to highlight the logic underlying the functioning of classical and quantum computers. Finally, it was used to compare the foundational experiments and the circuits, touching on the idea of the physical nature of information. This perspective proposes an alternative to the industry-based educational narrative, which organizes learning around knowledge standards and competency descriptors, and aims to train learners for participation in evolving technological ecosystems. Our conceptual–epistemological perspective seeks to open a space where the historical evolution aims to shed light on how a new ontological, epistemological, and axiological perspective is materializing in technologies that are changing both the society we live in and the science itself.

Speaker: Sara Satanassi

11:30 The Solvay Science Project and the Milestones of the first Quantum Revolution

The meeting patronized by the Belgian industrialist Ernest Solvay in Brussels, the first Solvay Council (1911), marked the beginning of the first quantum revolution. This event also led to the birth of the International Solvay Institute of Physics and its International Scientific Committee (ISC). Placed under the enlightened chairmanship of Hendrik A. Lorentz, the ISC organized five conferences that, in Heisenberg’s words, culminated in 1927 with the completion of quantum mechanics. However, these meetings were only part of a broader design envisioned by the Belgian philanthropist. The project comprised other very poorly known actions of the International Solvay Institutes, such as the granting of subsidies to physicists and laboratories from all nations. This talk aimed at clarifying how ISC started operating by dividing Lorentz’s chairmanship (1911 – 1927) into parts. First, we review the pre-WWI period to explain how ISC developed the subsidy program by complementing the discussions held at the first two Physics Councils. Then, we discuss some aspects of the post-war Solvay meetings that contributed to the birth of wave mechanics. The talk is based on a book recently published by World Scientific on the same subject.

Speaker: Alessio Rocci

11:50 Leonardo’s Holistic Insight on Quantum Inseparability

In the history of science, and of natural philosophy, action at a distance has been among the most controversial question, and the scientific community has repeatedly wavered between its acceptance and its rejection. Modern Galilean and Cartesian science were initially founded on its complete abandon, later reintroduced with Newton's principle of gravitation, refused again with the advent of Maxwell's electromagnetic theory, and finally reintroduced in a stronger form with quantum nonlocality. In this regard it is possible to propose to dwell on Leonardo’s holistic conception of nature, rejected by the mechanistic and reductionist view of Bacon, Galileo and Descartes, which stays at the basis of the ontology of classical physics. It would be possible to affirm that Leonardo’s perspective can be seen as a Renaissance foreshadowing of the relational worldview of quantum nonlocality. Both Leonardo and the entanglement suggest that to describe and understand quantum reality, one must look beyond isolated parts and embrace the idea of an unbroken wholeness of interconnected elements.

Speaker: Sara Taglialagamba