How gravity waves got scientists to look at the universe in a whole new way

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The anomalies and contradictions that scientists experienced during the course of research into the detection and deduction of gravitational waves revealed new insights about the epistemology of scientific experiments, and forced a paradigm shift in the scientific method.

If you don't find what you expect to find, does that mean it's not there or that you expected wrongly? | AURORE SIMONNET/SONOMA STATE/CALTECH/MIT/LIGO

It was reported last year that gravitational waves had finally been “seen” — a development which scientists say ranks on a par with the discovery of that “god particle” called the Higgs Boson and the structure of the DNA. Prof. Karsten Danzmann of Germany told the BBC “There’s a Nobel Prize in it, there is no doubt.” Prof. Stephen Hawking seemed to reinforce that view by saying that “gravitational waves provide a whole new way of looking at the universe”.

The existence of gravity waves was predicted by Einstein’s theory of General Relativity and is seen as yet another test for that theory. The acknowledged pioneer in gravity-wave detection was Joseph Webber, whose work at the University of Maryland was the source of much scientific controversy in the 1970s and became a central case study in an emerging discipline called the Sociology of Scientific Knowledge (SSK). In this article, I shall revisit that moment in the history of science and that emerging discipline.

 

 

In 1969, Joseph Weber published the results of his gravity wave experiment, claiming to have detected pulses of gravitational waves while studying the vibrations of an aluminium bar with a methodology of separating the “background noise” (constituted by natural vibrations of the bar and other factors) and the “signal” (those vibrations that could be considered to be the work of gravity waves) with a threshold amplitude for pulses to be considered as the result of gravity waves. Weber’s claims were met with skepticism, in large part due the high energy possessed by gravitational waves suggested by his results; Weber’s specific claim was high-flux gravitational waves rather than merely a confirmation of the existence of low-flux gravitational waves predicted by theory.

Weber’s modification of his experiment in response to sceptics and his claim to have observed simultaneous vibrations on two devices separated by a thousand miles with a sidereal periodicity (indicating a single source of the waves at the galactic centre) gave credibility to his results. By 1972, though, three other groups were working on the problem and all of them reported negative results beginning in 1973. By 1975, a consensus had crystallised against Weber’s results and no one was putting serious effort into even rejecting his claims.

Work on gravitational-wave detection, spurred by Weber’s claims, went on over the next two decades to be centered on the new technologies: cryogenic bars (which could detect lower frequencies with the low temperature also reducing natural thermal vibrations) and interferometry, rather than resonance technology for measurement. These culminated in 1992 in the Large Interferometry Gravitational Observatory (LIGO) at the centre of the current discovery. Weber remained an active physicist almost to the day of his passing at the age of 81 in the year 2000. Though dwarfed by subsequent research, his pioneering contribution has been generously acknowledged by those involved in current gravity wave–detection work.

The Experimenter’s Regress

With Weber’s passing, the British sociologist Harry Collins could claim in 2015 to be “nearly the last man standing” from the old days who could expect to witness the detection of gravitational waves. Collins engagement with gravitational wave research began when he studied the initial controversy over Weber’s work for his Ph.D. which began in 1971. The study of gravitational wave research, through which he developed a close relationship with multiple generations of scientists working on the problem, has remained central to his 40-year-long career, even as he has made remarkable contributions in other spheres.

 

 

After the publication of the negative results, the community of gravity-wave scientists seriously began to interrogate Weber’s results and his methods, and disagreed with him and with each other on the competence of various gravity wave detectors. In understanding how scientists approached Weber’s work, Collins invoked the concept of the experimenter’s regress. In an experiment designed to detect the existence of hitherto undetected phenomena such as high-flux gravity waves, the correct outcome (positive or negative detection) is unknown and depends on whether high-flux gravitational waves have a terrestrial existence. A good gravity-wave detector is required to establish the same. But the competence of the said detector cannot be judged unless we know the “correct” outcome of the experiment and so on, ad infinitum.

Collins used the term “experimenter’s regress” to describe the loop of dependence between theory and evidence, where the criteria for judging the competence of an experimental setup is dependent on the (yet unknown) correct outcome of the experiment. Any debate on the competence of an experiment is then coextensive with theoretical debate on the phenomena under question; the closure of the debate on competence being the characterisation of the phenomena the experiment seeks to study.

How can we be sure that we know something?

 

  Epistemology (n):

a branch of philosophy that investigates the origin, nature, methods,and limits of human knowledge. Basically, the methods we use and logical algorithms that govern how we interpret the world and convert information into knowledge.

Collins argued that epistemological criteria such as evidence and argument are insufficient to settle the existential status of a phenomenon. Through his examination of how scientists dealt with the question of high-flux gravity waves, he showed that the process of achieving closure was thus necessarily a social one. He argued that the debate — about the competence of the experiment, data analysis and the meaning of the results — was driven as much by factors such as a priori belief in the phenomenon, and by sociological factors such as the importance of theoretical continuity and preservation of the scientific order, as it was driven by purely epistemological criteria.

Thus, a decisive step towards closure was IBM physicist Richard Garwin’s decision to make a detector more sensitive than Weber’s, with its primary motive being to decisively refute the claims that high-flux gravity waves exist. Garwin’s a priori disbelief in Weber’s claims and his belief that evidence and arguments alone were insufficient to settle the debate was amply demonstrated by the fact that he circulated a paper on “pathological science” (whereby scientists “are tricked into false results ... by subjective effects, wishful thinking or threshold interactions.") to fellow physicists at a conference. Garwin’s efforts proved crucial in the scientific community burying belief in both the existence of high-flux gravity waves and the competence of Weber’s experimental apparatus.

 

Weber’s report of high-flux gravity waves was controversial as it required considerable modification in astrophysics; Collins argued had he merely detected the theoretically predicted low-flux waves, questions about the competence of his experiment may not have arisen.

The Sociology of Scientific Knowledge

As a discipline, the sociology of science has existed since at least the 1930s when Robert K. Merton published Science, Technology and Society in Seventeenth Century England in response to Soviet physicist and historian Boris Hessen’s The Social and Economic Roots of Newton’s Principia. The discipline focused on the social, economic, political and institutional context of scientific activity. With the publication of Harvard-trained–physicist-turned-Princeton philosopher-and-historian Thomas Kuhn’s The Structure of Scientific Revolutions in 1963 (which famously coined the phrase “paradigm shift”), scholars increasingly began to engage with the socio-scientific schema of how new ideas and theories establish themselves with the scientific communities.

Collins’ first paper published in 1975 came at a formative time for the discipline. Borne of a general rethinking of the social, economic and ideological role of science in the 1960s in Britain, the so-called “strong programme” in the sociology of scientific knowledge (which sought to extend sociological analysis to the core activities of science and engage with questions of power and authority) was in its infancy, gaining substantial visibility with the publication of Knowledge and Social Imagery by David Bloor, who (along with others) founded what became called “Edinburgh school”. The experimenter’s regress quickly became considered one of the most important contributions to the “strong programme”; around Collins himself grew the “Bath School” which lent itself to humorous titles of academic papers such as “Don’t throw the baby out with the Bath School” as scholars debated various aspects of SSK.

 

Demonstrating that the processes of scientific consensus–formation deviated substantially from the realm of logical reasoning alone, Collins’ work was well received in academic and activist circles increasingly questioning the authority of science and scientists. His 1993 book The Golem: What Everyone Should Know about Science came under much attack by scientists during the so-called science wars, which pitted scientists against (amongst others) postmodernists. In the belief that his work had become swamped by larger questions of anti-science postmodernism which justified controversies such as vaccine scares based on the idea that ordinary people’s wisdom was on a par with scientific understanding, Collins’ later work sought to establish a place for both scientific expertise and lay experience, with creative public policy applications in fields such as Genetically Modified Organisms where “the speed of politics is faster than the speed of scientific consensus formation”.

However, Collins never really saw anything amiss in the epistemological and sociological processes that play a role in the induction of new scientific ideas; according to him, these processes were essential to preserve the robustness of science as a knowledge-production activity despite the constraints such processes place the creativity of individuals. As he wrote in his seminal 1985 book Changing Order: Replication and Induction in Scientific Practice, for all its fallibility, science was the best institution for generating the knowledge about the natural world.

The outcome of these negotiations… is in every way proper scientific knowledge. It is replicable knowledge… There is nothing else for [Scientists] to do if a debate is ever to be settled and if new knowledge is ever to emerge… There is no realm of ideal scientific behaviour. Such a realm — the canonical model of science — exists only in our imaginations.

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