Neutrinos are currently the subject of intensive theoretical and experimental investigations, devoted to looking for new evidence of physics beyond the Standard Model of elementary particles. The solution of puzzling issues such as the mass-generation mechanism, the lepton number violation, the absolute mass scale and the possible Majorana nature of neutrinos would open also new perspectives on baryogenesis and the evolution of the universe. In this respect, the observation of the rarest and elusive neutrinoless double β -decay process is expected to play a prominent role, so that its relevance can be hardly underestimated. In the present work, we fully reconstruct the genesis and the early history of double β -decay, starting from Maria Goeppert-Mayer’s pioneering contribution, which promptly followed the first successful theory of β -decay provided by Enrico Fermi. Furthermore, we delve into Ettore Majorana’s neutrino theory and a variety of related investigations, finally focusing on the neutrinoless version of double β -decay, whose existence was suggested by Wendell H. Furry in 1939 and put forward as a viable tool to discriminate between the very (Dirac or Majorana) nature of the electron neutrino.
This contribution, based on a talk delivered at the Workshop Ukrainian Contributions to Particle Physics: History and Prospects, offers a personal memoir of Gleb Wataghin (1899–1986) and his role in the institutional development of modern physics at the University of São Paulo and in Brazil. Born in what is now Ukraine and educated in Turin, Wataghin joined the newly created university in São Paulo in 1934, where he helped establish a physics department and research school. He developed an internationally recognized cosmic-ray program and encouraged exchanges of students and researchers with leading scientific centres abroad. His students included Cesar Lattes, who participated in the discovery of the pion in 1947. After returning to Italy in 1949, Wataghin rebuilt the physics department in Turin while preserving strong ties with Brazil. This memoir is not intended as an archival study in the history of science. Instead, it is written from the perspective of a physicist who knew Wataghin in Campinas and whose career in ultra-high-energy cosmic rays traces back to him through her PhD advisor, Cesar Lattes. Viewed through this scientific lineage, Wataghin’s legacy combines scientific vision, institutional commitment, and intellectual leadership.
The 1935 Einstein–Podolsky–Rosen (EPR) paper, “Can Quantum–Mechanical Description of Physical Reality Be Considered Complete?”, stands as a landmark in the foundational debates over quantum mechanics. While the paper has since become one of Einstein’s most cited works, it initially received little attention, and the feature of non-locality, which was central to the argument in the paper, was largely neglected for decades. In this paper, I offer two reasons for this early neglect of non-locality in the immediate aftermath of EPR. First, early responses to the EPR paper defended the completeness of quantum mechanics by reformulating the thought experiment the authors had presented, thereby obscuring the feature of quantum mechanics the authors had wished to highlight. Bohr’s influential reply, for instance, substituted the specific thought experiment presented by EPR with the two-slit experiment, thus suppressing the entanglement between spatially separated systems. A second reason for the marginalization of non-locality was the tendency to see Einstein’s critique of quantum mechanics as proceeding from a commitment to determinism, though this in fact played no role in the EPR paper or in his later writings and correspondence. This paper argues that the failure to recognize non-locality was partly a result of the rhetorical manoeuvring by EPR’s critics, but also to a broader philosophical climate dominated by concerns over determinism, which effectively eclipsed all other conceptual issues, Only with Bell’s theorem in the 1960s did non-locality return as a serious focus of foundational inquiry.
The determination of the tropical year constitutes a fundamental problem at the intersection of celestial mechanics, astronomy, and historical timekeeping. As a physically defined quantity arising from the combined effects of orbital motion and axial precession, the tropical year provides the natural reference for civil calendar systems. This study examines the historical development of Julian-derived calendars as successive approximations to the tropical year, interpreted within a unified physical and mathematical framework. From the Julian calendar through the Gregorian reform to the Revised Julian system of Milutin Milanković, these calendars are analyzed as rational approximations to a slowly varying astronomical quantity. Within this framework, an adjusted Julian scheme is introduced as a theoretical extension of this tradition. Rather than constituting a proposal for reform, it serves to elucidate the limiting behavior of fixed calendrical systems when applied to a time-dependent physical quantity. The analysis demonstrates that calendar design is inherently epoch-dependent and reflects a continuous interaction between physical theory, mathematical structure, and historical practice. The results contribute to the understanding of timekeeping as a physical as well as cultural problem.
The tumultuous history of measurements of the deceleration parameter q0, one of a few key cosmological parameters, yields historical, theoretical, and epistemological reasons for studying it. A wide variety of observational methods and techniques, combined with evolutionary, astrophysical, cosmological, and observational selection effects, as well as various, and often contradictory assumptions behind various models, led to widely differing values of q0 (from − 2 to + 36!) over a span of half a century. Moreover, there was an inevitable epistemic trade-off between observational sensitivity and statistical wealth of data. While there certainly was a diversity of theoretical predictions for q0 among various cosmological models, our analysis indicates that the main historical cause of such a large and confusing scatter of empirical values was the persistent failure to appreciate the scope and tempo of evolutionary change in various astronomical sources. We survey and sort out this historical context, providing some preliminary general lessons for ongoing and future endeavors of similar complexity.
