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Review: Gravity’s Kiss


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Gravity’s Kiss: The Detection of Gravitational Waves
by Harry Collins
MIT Press, 2017
hardcover, 416 pp., illus.
ISBN 978-0-262-34003-8
US$29.95

A year ago Saturday, physicists announced one of the biggest discoveries in recent decades: the first direct detection of gravitational waves by the Laser Interferometer Gravitational-wave Observatory (LIGO), concluding a decades-long effort to confirm the existence of a phenomenon predicted a century earlier by general relativity (see “A thump in the night”, The Space Review, February 15, 2016). Since then, LIGO has detected more gravitational wave events: at a meeting of the American Physical Society in Washington last month, scientists said a recent run of LIGO, after being offline for much of 2016 for upgrades, detected two candidate gravitational-wave events that are still being analyzed. The discovery has also generated new enthusiasm for a space-based gravitational-wave observatory, the Laser Interferometer Space Antenna (LISA), to be lead by the European Space Agency with participation from NASA.

As an embed of sorts, Collins sits somewhere between an active participant in the LIGO effort and an outside journalist or historian.

The LIGO collaboration involved more than 1,000 scientists—and one sociologist. Harry Collins, a professor at the University of Cardiff in the UK who studies the social aspects of science, had been “embedded” into the LIGO effort for years and had been following the effort to study gravitational waves for more than four decades, longer than nearly all the scientists currently involved in LIGO. He had access to LIGO email listservs and telecons that, in mid-September of 2015, became frenzied as scientists analyzed an event that turned out to be that historic gravitational wave discovery.

Gravity’s Kiss is his inside account of that discovery, based largely on those communications he had access to. There was, interestingly, little doubt that the event LIGO recorded, formally known as GW150914 but often simply called “the Event,” was a real gravitational wave, particularly when scientists ruled out it being a “blind injection” into their data analysis pipeline as a test. The signal was so strong that there was little risk of it being random noise or an instrumentation issue. The discussion soon turned to refining the analysis to identify the source of the waves (merging black holes dozens of times as massive as the Sun) and how to publish the results.

As an embed of sorts, Collins sits somewhere between an active participant in the LIGO effort and an outside journalist or historian. He is conversant enough in the science to be able to follow the work going on, with assistance from some of the scientists involved, but is not directly involved in the research itself. That email traffic and those telecons, supplemented with some additional email inquiries and phone interviews, are his window into the project; that access is greater than others not involved in LIGO had, but also less than those actively working on the project who also had face-to-face interactions and other channels. But, like LIGO project members, he was sworn to secrecy while the analysis of the event was ongoing, which, he recalled, required him to dissemble when contacted by journalists following up rumors about the discovery.

Collins was not particularly fond of that secrecy, which restricted scientists from discussing their discovery with colleagues outside the LIGO collaboration until the publication of the formal discovery paper and a press conference about it. That didn’t stop the rumors, though, which began as a trickle just days after the event and became a torrent by early 2016. Indeed, by the time of the press conference, it would have been a surprise if scientists didn’t announce a gravitational wave discovery; the only questions involved specific details, many of which has also leaked out in advance.

Like LIGO project members, he was sworn to secrecy while the analysis of the event was ongoing, which, he recalled, required him to dissemble when contacted by journalists following up rumors about the discovery.

Gravity’s Kiss is focused on the discovery itself, from the first detection of the event through the formal public announcement and immediate aftermath. (That includes discoveries of additional events, including one dubbed the “Boxing Day event” because it took place on December 26, 2015, that influenced the interpretation of the initial discovery.) It is not an overall history of gravitational wave science in general or LIGO in particular, beyond a few pages providing a high-level overview. Collins has written several other books about earlier stages of the gravitational-wave search, which he references frequently throughout this book.

Collins’ unique role in the project makes Gravity’s Kiss an unusual book. It is not quite a first-person account from a scientist directly involved in the project, but it is also not a dispassionate account by a historian (Collins acknowledges in the text that he takes a different approach than a historian would to determine if, say, a particular anecdote about the project was actually true.) His sociological insights offer an interesting dimension, probing various aspects of how the science is done. On the other hand, some of the personal details he includes, such as his email archiving techniques or how his personal knowledge of gravitational-wave science has waxed and waned over the years, might not be interesting, given he’s just an observer of the research and not a participant.

Gravity’s Kiss is not the first book about the discovery of gravitational waves: Black Hole Blues, a book published last year about gravitational-wave research and LIGO in general, was able to incorporate the discovery into an epilogue (see “Review: Black Hole Blues”, The Space Review, April 18, 2016). That book was a more general scientific and historical account by a physicist familiar with the subject and its key individuals. This book, though, is focused on the historic discovery and how it played out as seen by an embedded non-scientist observer. It’s an interesting account of both the discovery and his implications about how science is done, but unlikely to be the final word on this achievement.


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