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A tour de force of the cosmos

23 Feb 2017
Taken from the February 2017 issue of Physics World

Mapping the Heavens: the Radical Scientific Ideas That Reveal the Cosmos
Priyamvada Natarajan
Yale University Press 288pp £16.99hb

Flare with flair

There is something rather strange about how physicists, both young and old, perceive science. I am sometimes confronted with the realization that I too am susceptible to a host of strange, if not pathological, notions: that science is pure and logical; that it is distant from the apparent caprice of more human-centred realms such as art or politics or sociology; and that this difference somehow makes science clean and ideal. However, the more I engage with the infrastructures of science – its reliance on both individuals and groups; its continuous need for advancing technologies; and the indelible effects of human rivalries, camaraderie and oversights – the more my notions of scientific idealism give way to a better understanding of scientific realism.

It is through this lens that I find Priyamvada Natarajan’s book, Mapping the Heavens: the Radical Scientific Ideas that Reveal the Cosmos, to be an instructive and thought-provoking exploration of the connections, tensions and mishaps that so often accompany scientific venture. The book delves into some of the most important and influential discoveries in cosmology – from exoplanets to dark energy and other universes. Through the stories of individuals and collaborations that have transformed cosmology, Natarajan – an astrophysicist at Yale University – attempts to blur the lines between the products of science and its human creators.

In doing so, she effectively renders modern physics and cosmology as an inherently anthropological search for answers to deep, fundamental questions. What is the Earth’s place in the universe? Is there a beginning and an end to all things? Is there more to our universe than we currently know? Indeed, Natarajan’s contemplations on various historical parables serve as a useful reference for today’s early-career scientists, who may find themselves in a state of uncertainty as they navigate the realms of “big science”, with its large collaborations and complex social structures.

On starting my first postdoctoral position at Cardiff University in the UK as part of the Laser Interferometric Gravitational-Wave Observatory (LIGO) collaboration, on 1 September 2015, I could not have predicted the historical observation we were to make a mere 13 days later. A gravitational wave, resulting from the collision of two black holes some 1.3 billion light-years away, rippled through the Earth and caused LIGO’s twin interferometers – in Livingston, Louisiana and Hanford, Washington – to squeeze and stretch by an infinitesimal but measurable amount.

It is expected that LIGO’s future observations will empower us to make novel contributions to many of the topics in astronomy and cosmology that the book explores. However, just as Natarajan traces the historical passage of astronomy and cosmology from fringe topics to venerated research fields, LIGO and its supporting communities are currently undergoing the process of mapping out an entirely new scientific subfield: gravitational-wave astronomy.

As LIGO scientists seek to define gravitational-wave astronomy with the insights gained from new observations, the field’s inherent ties to cosmology make Natarajan’s exploration valuable for any gravitational-wave enthusiast. This is perhaps not the most surprising claim, as gravitational physics – founded by Isaac Newton, and then reprised and strengthened by Albert Einstein – is the nexus for many stories in astronomy and cosmology. From the existence of black holes, to dark matter and dark energy, the impact of Einstein’s theory of gravity cannot easily be downplayed.

However, scientists may also often forget (either in exuberance over Einstein’s legacy or due to the seemingly deterministic nature of scientific progress) what Natarajan goes through a mildly repetitive exercise to reinforce: that not only do human biases impact the execution of science, but also they often impede and even obscure its progress as a whole.

Indeed, bias affects even the best of scientists, as Natarajan points out – Einstein’s long-held, incorrect belief in a static universe perfectly elucidates this point. The initial stubbornness of the astronomy community to accept the idea of dark matter, despite considerable observational evidence, shows how bias can affect entire groups. At the same time, Natarajan also describes how academic tensions and scientific scepticism go hand in hand with theory and evidence, to give way to and powerful consensus. Such agreement is the precursor to crucial, paradigm-changing discoveries that inevitably impact a scientific field, as well as the lives of every individual scientist.

Indeed, during my time at Cardiff, I have witnessed first-hand the changing trajectory of belief in a theory that results when heavy scepticism meets robust evidence. Looking back at an early staff meeting, a particular individual doubted the detectability of gravitational-wave signals and openly mocked the decades-long efforts of the group. It was quite interesting to see both heckler and advocate toast with champagne a few months later, after all arguments had been put to rest. Although I am certainly biased by my experiences as a gravitational-wave astronomer, I would recommend Mapping the Heavens to readers from middle-school level onwards and from a wide range of backgrounds. Any minor wrinkles in the text’s construction and style are outweighed by insights gained into modern physics’ history via Natarajan’s skilful writing.

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