Abstract This paper focuses on the state of astronomical practice when signals were limited to the known electromagnetic spectrum, from gamma rays to radio waves, but including the first particle detections, such as cosmic rays and neutrinos. It argues that the main set of practices that characterize multi-messenger astronomy have long been part of the scientific culture of what is still commonly called “astrophysics,” for they have a fundamental connection with correlation techniques and practices. After preliminary remarks on the nature of correlation in astronomy, I limit my attention to key correlations that helped to establish astrophysics mainly through the application of spectroscopy. Spectra were the first major entrant: describing stars and classifying them in physically meaningful terms. I cover the challenges of definition and standardization of stellar spectra and how to describe them and then relate them to other known stellar phenomena. I examine correlations such as the relation of the relative strengths of stellar spectral lines to the physical nature of the stars, the relation of stellar color to stellar luminosity, and the relation between the absolute brightness of a class of variable star called Cepheids to the periods of their brightness variations. I finally look at this correlation leading to the acceptance that the universe is composed of vast clusters of stars called galaxies and then that they are moving away from each other, resulting in a framework that holds that the universe is expanding.

Abstract In recent years, the environmental impact of warfare has made front-page news. Discussions about “ecocide”—a term first proposed in 1970 by Yale biologist Arthur W. Galston to describe the large-scale destruction of ecosystems during the Vietnam War—have come into the spotlight. The preparation and conduct of war, along with the social, economic, and scientific reorganisation that accompany it, offer rich topics for historians of science and technology interested in the environment. At the same time, since the turn of the 21st century, the study of war has emerged as a burgeoning subfield within environmental history. Edmund Russell's War and Nature (2001) inspired extensive scholarly research exploring the direct and indirect impact of military operations on the environment, as well as their legacies for human and non-human life. This review article focuses on how the development of the environmental history of war subfield has intersected with the history of science. First, it highlights how Russell's work has engaged audiences in both the history of science and the history of technology. In its early years, however, the field served as a bridge between environmental history and military history and delved into a classic theme of environmental history: conservation. Second, it discusses how studies on war and environment expanded beyond the battlefield to encompass militarised landscapes and the effects of military supply chains, among other topics. Third, it highlights how research on Cold War science provided a key site for intellectual exchange between environmental history of war and the history of science. Finally, it identifies several research avenues that could foster further collaboration between these fields, including: the concept of ecocide, the study of environmental infrastructure and envirotechnical objects, the epistemic foundations of military environmentalist discourses, and the significance of environmental data production and use in warfare.

Abstract In April 2019, the Event Horizon Telescope Collaboration released the first image of the shadow of a black hole. Starting off with its early history, and then moving on to these recent developments, we trace the concept of directness in black hole imaging. Throughout this history, “direct observation,” “direct image,” “direct evidence,” and “direct visual evidence” were almost never defined and yet such notions came to be used to argue that imaging would be the most convincing evidence for the existence of black holes. Within the Event Horizon Telescope Collaboration, views about what directness entailed differed and revealed subtle differences between various stances on evidence and visuality. Following the study of directness in black hole imaging, we compare these uses of directness with cases from black hole research more broadly. From a philosophical perspective, “directness” is used to compare one observation to another, across dimensions of varying epistemological significance. This can have implications for the perceived prestige of the observations. However, any connection between directness and epistemological value is highly dependent on the details of both the observation itself and the notion of directness being deployed to describe it.

Abstract Multi-messenger astronomy has recently emerged and gained prominence in the scientific literature as a novel form of big science, characterized by organizational structures and epistemic practices that distinguish it from traditional large-scale endeavors. Despite scientists' recognition of the profound conceptual and social reconfiguration accompanying its rise, no in‑depth historical analysis has yet been undertaken. The present special issue addresses this gap by offering the first historical exploration of the field's emergence. In the introduction, we examine the challenges of tracing the complex historical and conceptual relationships between multi-messenger astronomy and the diverse scientific domains now encompassed within it—especially astroparticle physics, multi-wavelength astronomy, gravitational-wave astronomy and neutrino astronomy—and of delimiting both the temporal span and the disciplinary contours of what should be included in its history. Underlying these efforts is the persistent ambiguity of the term “multi-messenger astronomy,” which remains contested among practitioners. To navigate these complexities, we discuss how historical analyses lead to regarding multi-messenger astronomy not merely as a sum of disparate astrophysical methods but as a novel integrative paradigm with its own internal logic and collaborative practices. Our review of practitioner narratives further reveals at least three distinct perceptions of the epistemic cultures that shaped the field's rise: those who emphasize the role of real-time alert systems, those who stress the continuity of individual messenger disciplines, and those who highlight proto-multi-messenger episodes and near-misses. Finally, we introduce the contributions to this special issue, highlighting how these essays illuminate the interpretative and epistemological dimensions that compel us to revisit foundational debates about the field's defining characteristics and the interplay of diverse research traditions—inviting an interdisciplinary dialogue among historians, philosophers, and scientists on what truly constitutes multi-messenger science.

Abstract The paper explores the historical development of supernova research in the 20th century and examines its role in the emergence of multi-messenger astronomy. Through an analysis of primary scientific literature and review sources, we show that theoretical and experimental investigations of supernovae, from the 1930s to the supernova 1987A and beyond, have fostered a crucial shift in astronomical research. Building on conceptual tools from history of science and social studies—such as Galison's “trading zones,” Star and Griesemer's “boundary objects,” and Renn's notions of “challenging objects” and “borderline problems”—this analysis shows how supernovae served as both enablers and drivers of productive confrontation and exchanges across disciplinary boundaries. Through key episodes we discuss how they bridged different research domains, shaping hybridized practices and expertise, in order to address complex questions that no single field could resolve. Particular attention is given to the detection of SN1987A. Though not yet embedded in a mature multi-messenger framework, it revealed the latent infrastructure, interpretive gaps, and epistemic promise of a globally coordinated, real-time, multi-signal astronomy, anticipating more integrated approaches. Following this turning point, the article traces how collaborative practices gradually solidified into enduring forms of interdisciplinary work, laying the epistemic groundwork for multi‑messenger science long before the term gained currency. We argue that supernova research functioned as a long-term trading zone, where experimental practices, theoretical models, and instrumentation co-evolved across disciplinary boundaries. By reconstructing this process, the paper contributes to a historical understanding of how new scientific fields emerge through the reconfiguration of existing ones. This paper forms the first part of a twofold study on the emergence of multi-messenger astronomy as a new field of scientific inquiry. The companion study will integrate this contribution, by tracing the rise and consolidation of multi‑messenger research networks through co-authorship and co‑citation analysis in the 21st century.

Abstract Cooperative phenomena in science are frequently viewed as the result of social forces and material conditions within a given social system of knowledge. In this context, scientific requirements often remain in the background, if not entirely overlooked, in discussions about what motivates cooperation. This paper challenges such interpretations using examples from the history of neutrino astronomy and recent multi-messenger discoveries. Revisiting the hierarchy of models proposed by Suppes (1962), it argues that the ethos of collaboration in multi-messenger astrophysics is primarily driven by epistemic constraints embedded within the models describing typical multi-messenger sources and processes. These constraints necessitate cooperation among multi-messenger astronomers, regardless of other motivations for their collaborative efforts and despite the complexities and challenges involved.

Abstract After exploring the role of supernova research—understood as epistemic laboratories—in the later emergence of multi-messenger astronomy in the first part, this second article of our two-part study examines the rise and consolidation of the research field in the 21st century. Although often heralded as a novel and transformative approach, multi-messenger astronomy has roots in the convergence of earlier practices such as multi-wavelength astronomy, astroparticle physics, and gravitational-wave detection, each with their own distinct and evolving scientific subcultures. The study explores how these traditions coalesced, analyzing the processes that linked subcommunities and the roles of institutional frameworks, scientific collaboration, and thematic integration in shaping the field. The paper combines quantitative analysis of scientific literature with the close reading of strategically selected scientific publications. Network science tools are employed in an exploratory fashion to trace patterns of collaboration and the evolution of research topics. We argue that the scientific literature explicitly framing itself as multi-messenger astronomy can be divided into three periods. The exploratory phase (1997–2008) saw very few papers using the term, largely within nascent programs in very-high-energy gamma-ray astronomy and astroparticle physics. During the emergence phase (2009–2015), researchers pursued the conceptual and operational integration of astroparticle physics in anticipation of the advent of gravitational-wave astronomy, with gamma-ray studies emerging as a central connecting research field in the network. Finally, the consolidation phase (2016–2023) was sparked by the first direct detection of gravitational waves and saw the realization of the multi-messenger observational programs previously envisioned. Our analysis reveals, first, that astroparticle physics served as the cradle of the multi-messenger approach—initially integrating high-energy neutrinos, cosmic rays, and gamma rays, and later incorporating gravitational waves both conceptually and, following their detection, empirically into a unified framework. Second, we show that forward-looking imaginaries—particularly the anticipation of gravitational-wave discoveries—profoundly shaped research practices and priorities.