Cosmology’s Century
PJE Peebles Princeton University Press £30 HB
Among astronomy’s many achievements in the 20th century, the prediction and discovery of the cosmic microwave background radiation (CMBR) is surely one of the greatest. It not only clinched the case for the Universe’s origin in a ‘Big Bang’ 13.8 billion years ago, but also provided a new means of studying the early cosmos. As a PhD researcher at Princeton in the early 1960s, Jim Peebles was among the team that predicted the CMBR’s existence, while his subsequent career focused on developing ideas about the evolution of cosmic structure and the role of mysterious dark matter, for all of which he was awarded the 2019 Nobel Prize in physics. It’s hard then to imagine anyone better placed to recount the inside story of modern cosmology. Unusually among his contemporaries, Peebles has always taken a keen interest in the origins of the ideas with which he wrestles each day, and his latest book is a magisterial summing up of a century of science, from Einstein’s 1915 general theory of relativity, to the turn of the millennium and beyond. Rather than opt for a strictly chronological approach, he tackles his subject through the development of particular ideas and concepts, such as Einstein’s principle that the Universe must be homogeneous (uniform) on the largest scale, the various ‘ fossils’ (including the CMBR) that can tell us about the early Universe, and the rival and sometimes complementary models used in modern cosmology. Delving into archives and recalling a lifetime of contacts with other key players, he offers a unique perspective on how some of the mind-bending ideas we now take for granted came about. The academic structure of numbered sections and subsections, and exhaustive references may be off-putting to some, and of course the use of equations is sometimes unavoidable when discussing the scientific
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minutiae, but Peebles’ text is a model of unshowy clarity throughout, and the gist of his arguments and stories remains easy to follow even if you want to ‘ skip the math’. For anyone seriously interested in the ways of science and how we came to understand our place in the Universe, this is essential reading. ★★★★★
Giles Sparrow is a science writer and a fellow of the Royal Astronomical Society