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(My quick check online showed that pairs from three species of cotinga sell for US$25 to $45. I easily found feathers on sale from birds on the International Union for Conservation of ’s Red List of Threatened Species.) US thief Willie Sutton allegedly said that he robbed banks because “that’s where the money is”. Museums are where the feathers are. In July 2009, senior curator Mark Adams found the drawers with missing specimens; 16 months later, Rist was caught. He pleaded guilty to burglary and money-laundering. The court fined him £125,150 (US$200,000 at the ), of which he had about 10%. He also got a mere 12-month suspended sentence, owing to a diagnosis of Asperger’s syndrome (an autism spectrum disorder). Of the 299 skins stolen, police retrieved only 102 with the labels intact. More had been stripped of the essential data that such labels provide, and 106 were missing. John- son’s exhaustive sleuthing tracked down some feathers in 2016, but more. Museum specimens are a unique, con- textualized archive, as Robert Prys-Jones, a scientific associate at the Natural Museum, makes clear in the book. They hold about where and when species lived, who collected them and perhaps why; and they can be studied for visual and genetic clues. But after interviews with individuals in the fly-tying community, Johnson feels that only some are horrified by the theft. His investigations revealed that the bulk of the birds “dissolved into the bloodstream of the Stop all the clocks feather underground”, some realms of which seemed to trade in endangered species and flout the on International Trade Andrew Jaffe probes Carlo Rovelli’s study arguing in Endangered Species of Wild Fauna and that physics deconstructs our sense of time. Flora. As Blinken told me, the art can become “a pursuit of perfection so intoxicating that its practitioners lose all sense of ”. ccording to theoretical physicist network of events onto which we project The Feather Thief is a riveting read. It also Carlo Rovelli, time is an : sequences of past, present and . The stands, I believe, as a reminder of how an our naive of its flow whole obeys the of quantum obsession with the ornaments of nature — be Adoesn’t correspond to physical . and thermodynamics, out of they feathers, bird eggs or ivory — can wreak Indeed, as Rovelli argues in The Order of which time emerges. havoc on our scientific heritage. ■ Time, much more is illusory, including Rovelli is one of the creators and ’s picture of a universally tick- champions of loop quantum theory, Stuart Pimm is professor of conservation ing clock. Even ’s relativistic one of several ongoing attempts to marry at the Nicholas School of the Environment space-time — an elastic manifold that con- with general relativ- at Duke University in Durham, North torts so that local differ depending ity. In contrast to the better-known Carolina, and directs the non-profit group on one’s relative speed or proximity to a theory, loop does not SavingSpecies, www.savingspecies.org. He mass — is just an effective simplification. attempt to be a ‘theory of ’ out of tweets at @StuartPimm. So what does Rovelli think is really going which we can generate all of particle phys- e-mail: [email protected] on? He posits that reality is just a complex ics and gravitation. Nevertheless, its agenda

Drawing Physics Grave New World: The End of Globalization, Don S. Lemons MIT Press (2018) the Return of History For millennia, drawings have elucidated Stephen D. King Yale Univ. Press (2018) chewy in physics, providing a “pre- Economist Stephen D. King’s analysis of mathematical picture of reality”. Don Lemons globalization is searing and timely, offering delves into the archive for powerful sketches historical lessons on how political narratives representing and results from Isaac that abandon the global agenda, such as Brexit, Newton’s colour theory to the . threaten our economic order.

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into three parts. In the first, “The Crumbling between them. of Time”, Rovelli attempts to show how In the final section, “The Sources of established physics theories deconstruct Time”, Rovelli reconstructs how our our common-sense ideas. Einstein showed have arisen, from aspects of us that time is just a fourth dimension and thermo­dynamics and quantum mechanics. that there is nothing special about ‘now’; He argues that our perception of time’s flow even ‘past’ and ‘future’ are not always well depends entirely on our inability to see the defined. The malleability of space and time world in all its detail. Quantum uncertainty mean that two events occurring far apart means we cannot know the positions and might even happen in one order when speeds of all the particles in the Universe. viewed by one observer, and in the opposite If we could, there would be no entropy, and order when viewed by another. no unravelling of time. Rovelli originated Rovelli gives good descriptions of the this ‘thermal time hypothesis’ with French classical physics of mathematician Alain Newton and Ludwig Connes. Boltzmann, and The Order of Time of OUR PERCEPTION OF is a compact and through the lenses of elegant book. Each Einstein and quantum TIME’S FLOW chapter starts with mechanics. There an apt ode from are parallels with DEPENDS ENTIRELY classical Latin poet thermodynamics­ and ON OUR Horace — I particu- Bayesian probability larly liked “Don’t theory, which both INABILITY attempt abstruse cal- rely on the culations”. And the of entropy, and might TO SEE THE WORLD IN writing, translated therefore be used to from Italian by Erica argue that the flow ALL ITS DETAIL. Segre and Simon of time is a subjective Carnell, is more styl- feature of the Uni- ish than that in most of joining up these two fundamentally verse, not an objective part of the physical physics books. Rovelli ably brings in the differing laws is incredibly ambitious. description. thoughts of philosophers Martin Heidegger Alongside and inspired by his work in But I quibble with the details of some of and Edmund Husserl, sociologist Émile quantum gravity, Rovelli puts forward the Rovelli’s pronouncements. For example, it is Durkheim and psychologist William James, of ‘physics without time’. This stems far from certain that space-time is quantized, along with physicist-favourite philoso- from the that some equations of quan- in the sense of space and time packaged phers such as Hilary Putnam and Willard tum gravity (such as the Wheeler–DeWitt in minimal lengths or periods (the Planck Van Orman Quine. Occasionally, the writ- equation, which assigns quantum states to length or time). Rather, our understanding ing strays into floweriness. For instance, the Universe) can be written without any peters out at those very small intervals for Rovelli describes his final section as “a fiery reference to time at all. which we need both quantum mechanics and magma of ideas, sometimes illuminating, As Rovelli explains, the apparent exist- relativity to explain things. sometimes confusing”. ence of time — in our and in In part two, “The World without Time”, Ultimately, I’m not sure I buy Rovelli’s physical descriptions, written in the math- Rovelli puts forward the idea that events ideas, about either or ematical languages of (just a word for a given time and location the thermal time hypothesis. And this book Newton, Einstein and at which something might happen), rather alone would not give a lay reader enough Erwin Schrödinger than particles or fields, are the basic con- information to render . The Order — comes not from stituents of the world. The task of physics of Time does, however, raise and explore big , but from is to describe the relationships between issues that are very much alive in modern ignorance. ‘For- those events: as Rovelli notes, “A storm physics, and are closely related to the way ward in time’ is the is not a thing, it’s a collection of occur- in which we limited observe and direction in which rences.” At our level, each of those events participate in the world. ■ entropy increases, looks like the of particles at and in which we gain The Order of Time a particular position and time; but time Andrew Jaffe is a cosmologist and head of information. CARLO ROVELLI and space themselves really only manifest astrophysics at Imperial College London. The book is split Allen Lane (2018) out of their and the web of e-mail: [email protected]

Life’s Vital Link: The Astonishing Role Mistress of Science of the Placenta John S. Croucher and Rosalind F. Croucher Y. W. Loke Oxford Univ. Press (2018) Amberley (2018) This exploration of the placenta’s Nineteenth-century British mathematician Janet devotedly details the ‘forgotten’ organ’s vital Taylor has been overlooked by history, yet she role in the womb, and other complex functions. invented navigational tools such as the mariner’s Immunologist Y. W. Loke also ponders how such calculator, founded an academy and authored findings could provide insight into his field. textbooks. A fitting tribute to a gifted trailblazer.

©2018 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. ©2018 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ght19s re sAPRILerved. 2018 | VOL 556 | NATURE | 305