Dissertation Grant: Engineering Stillness: The History of Site Selection and Signal Epistemological Development of the Laser Interferometer Gravitational-Wave Observatory (LIGO)

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This award supports a doctoral dissertation research project in history of science on the Laser Interferometer Gravitational-Wave Observatory (LIGO). The project has two goal. It will provide a better understanding of the process through which the paired sites of Hanford (Washington) and Livingston (Louisiana) were selected, and of how scientists and engineers using LIGO came to distinguish background noise from gravitational wave signals. To extract a very small signal from vast amount of noise, LIGO must exclude all local disturbances not present at both sites; to maximize the likelihood of being able to filter out such disturbances from the background, scientists and engineers had to choose relatively quiet sites. Once the sites were chosen, they had to identify and understand the sources and characteristics of the local disturbances (e.g., logging activity, earthquakes, and traffic) at the selected sites in order to maintain and improve the capacity to detect gravitational waves. A sociological understanding of local life became integral to the process of characterizing local disturbances and so to the larger aim of discerning gravitational wave signals from the background noise. The novel term “signal epistemology” is used by the researcher to refer to the acquiring, combining, and applying a hybrid of technical and social knowledge about vibrations within LIGO's interferometers. The results of this research will serve as a resource for future site selection by LIGO for the placement of additional large-scale interferometers and other large-scale physics experiment enterprises which must consider the land due to the sensitivity and size of their instruments, and it will serve as a case study that provides insights for other nationally funded big science projects. This research project on the early history of LIGO has three distinct components. First, it analyzes the LIGO site selection process. Second, it examines the construction of LIGO's signal epistemology, especially with respect to the question of how LIGO's environment pertains to the operation and output signals of its interferometers. Third, it studies the importance of maintaining interferometer sensitivity and a still experimental environment relative to its actual geographic location, so that LIGO scientists can extract the incredibly minute gravitational wave from the background noise. The overarching issue addressed by the project is the perennial question of how land characteristics and placement choices affect large-scale physics experiments and how considerations of land and territory became integral to the performance of experiments on such sites. Existing literature uses sociological methods to examine interpersonal relationships in the site selection process. By contrast, this research fills a critical gap in our understanding by using archival record analysis to analyze LIGO's development, placement, design evolution, experimental runs and its understanding of distinctions between gravitational wave signals and terrestrial background noise. The project will address the experience of those who occupy the land surrounding LIGO's sites, with the aim of showing how their relationships with and knowledge of the land became part of LIGO's gravitational wave experiments and interpretation of data. The points of intersection between local knowledge and the knowledge acquired by non-resident experts entailed in site selection is a novel feature of the project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.