Astroparticle physics is a new field at the intersection of particle physics, astronomy, and cosmology, emerging in the period ranging from the mid-1970s to the second half of the 1980s. It led to the reorientation of research agendas and to the undertaking of new research projects typically representative of the field, aiming to answer fundamental questions related to the history of the universe.
Preliminary research has been done within the project “History of Astrophysics, Astronomy, and Space Sciences in the Max Planck Society” and resulted in a deeper understanding of how the intrinsic multidisciplinary reality characterizing the post-war history of the Max Planck Institutes for Physics, for Astrophysics, and for Nuclear Physics favored—during the 1980s and early 1990s—the institutional establishment of astroparticle physics within the Max Planck Society. It has also clarified how the three institutes achieved global leadership in solar-neutrino astronomy and in the entirely new research fields of gravitational-wave and ground-based gamma-ray astronomy. Understanding how—in developing new methods and scientific interests driven by fundamental research questions—different scientific traditions found varying paths to modern astroparticle physics, represents a perfect and relevant case study which throws light on the main aspects of how the identity of this multifaceted field took shape and became a recognized realm within the scientific community.
These results have contributed in shaping the chapter “Global Leadership in Emerging Fields: Towards Astro-Particle Physics, Relativistic Astrophysics, and Multi-Messenger Astronomy,” which will be published in the forthcoming volume Astronomy, Astrophysics, and Space Science in the Max Planck Society (Brill 2022). In addition, the project has influenced the chapter “Gravitational-Wave Research as an Emerging Field in the Max Planck Society. The Long Roots of GEO600 and of the Albert Einstein Institute,” appearing in the volume The Renaissance of General Relativity in Context, edited by A. Blum, R. Lalli and J. Renn (Boston: Birkhäuser, 2020.) Both works were written in collaboration with Juan-Andres Leon.
Such studies have also highlighted how detecting techniques grew in size, from small Geiger-Müller counters, up to giant detector arrays distributed over areas measured in square kilometers in order to compensate the low probability of ultra-high energy events with a large monitoring surface. The same well-established practice of studying rare events was then transferred to experiments hunting for solar neutrinos; to ground-based gamma-ray astronomy; and to experiments transforming ice, as well as fresh and sea water into both targets and detectors for cosmic neutrinos, proton decay, dark matter candidates, and other exotic particle-relics of the early universe. At the intersection of different research areas, material cultures, detection approaches, and communities of practitioners; astroparticle physics got its modern identity and created a new unconventional breed of astronomers. A brief outline of such developments is presented in the contribution “Thinking Big: How Large-scale Detectors Set the Stage for the Emergence of Astro-particle Physics. A Short Survey” together with Juan Andres Leon.
In the 1970s, physicists with expertise in the theory of elementary particles joined astronomers in bringing new intellectual tools to study how the consequences of novel concepts in particle physics would play out in the universe. Within the next decade, astroparticle physics took shape; it emerged from nuclear and particle physics, astrophysics, astronomy, and cosmology as a research field in its own right.
In order to deeply investigate the emergence process, I dedicate considerable attention to the creation of a large bibliographic database—ranging from the 1940s to the 2000s—whose preliminary qualitative analysis strongly suggests that the coming into being of astroparticle physics should not be interpreted tout court as a field “retrospectively evolving from the confluence of other fields” (which today form the heart of its research agenda,) but rather as a sort of “phase transition” into a new knowledge system. This new system materializes around the establishment of novel synergies and scientific strategies and connects traditionally separate theoretical, experimental, and observational methodologies as well as culturally different scientific communities from the early 1970s to the mid-1980s, with some visionary anticipations during the 1960s. According to this cross-fertilization view, fundamental questions addressing the origin and evolution of the universe, its constituents, and its fundamental forces involve boundary problems shared by theoretical physicists, high-energy and cosmic-ray physicists, nuclear astrophysicists, and astronomers, who all became entangled in the first crystallization nucleus. Together, they provided an integrated view of the micro- and macrocosm around which the relationship between astronomy, astrophysics, cosmology, and particle physics was gradually redefined. The cooperation of different disciplines that combined methods, research dynamics, and instruments typical of high-energy physics with those of the most advanced imaging techniques of the cosmos by astronomers complemented both accelerator-based particle physics and telescope-based astronomy. The identity of the new research field materialized through the transition of the many theoretical conceptual frameworks of the 1980s into the full-fledged astroparticle physics field of the 1990s—being progressively driven by experiments and observation.