The discovery of cosmic microwave background radiation—an inflection point in postwar cosmology—has not lacked chroniclers, but few have drawn deeply upon the available archival record. Many accounts emphasize the serendipitous manner in which the radiation was detected. This article redefines the relative contributions of luck, skill, and circumstance to the discovery by thickening the contexts in which it occurred. In its emphasis upon the material conditions of scientific enquiry, the development of technical expertise, and the permeability of disciplinary boundaries, the article situates the discovery in the sort of explanatory context more familiar from histories of Cold War nuclear and electronics research, where funds flowed freely across a broad front of institutions and subject fields, underwriting innovation and exchange, and incentivizing the instrumentalization of basic knowledge to address real world problems—in this case, microwave radio noise. It was not research to resolve the “big-bang”/“steady-state” controversy that pulled the radiation within range of detection, but a protean technoscientific program to improve signal-to-noise ratios. The accumulation of proficiency in microwave communications at Bell Laboratories, where the radiation was detected, was as significant to the breakthrough as the expertise in theoretical astrophysics available at Princeton, where the Bell Labs measurements were linked to the “big bang.” Princeton physicists, led by Robert Dicke, had already embarked on their own independent effort to detect the radiation, but evidence suggests they may not have succeeded absent the instrumental contributions made by Bell Labs.

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