When baguette meets coffee

Nature 411, 637 - 638 (2001) © Macmillan Publishers Ltd.

VINCENT DUSASTRE
Vincent Dusastre is an associate editor at Nature.
Entrer en matière: Les atomes expliquent-ils le monde? [in French] by Pablo Jensen
Seuil: 2001. 247 pp. 19.82 euros

The French term entrer en matière can mean either 'getting into matter' or 'introducing a given topic'. Pablo Jensen - a materials physicist at the Université Claude Bernard's Laboratoire de Physique des Matériaux in Lyon - proposes to do both in his book. He aims to take the reader on a journey into the physics of matter and also to give non-scientists an introduction to his research discipline.

The basic idea is to address down-to-earth questions about the physical and chemical principles governing the properties of matter for readers with minimal scientific knowledge. This refreshing approach is directly inspired by an initiative, called the 'Cafés des Sciences', which was started in 1997 by scientists at the Centre National de la Recherche Scientifique in Lyon, and now extends to the rest of France. Its aim is to improve the dialogue between science and society.

Entrer en matière is particularly accessible because its various sections can be read independently, depending on your mood and your knowledge of the subject. Jensen lucidly portrays the developments and intellectual challenges encountered by physicists in their attempts to describe and explain the complex and diverse behaviour of matter, and the challenges that remain. And he illustrates his story with practical examples that have economic, environmental, historical and even artistic applications.

The book starts by posing basic questions about the different states of matter - solid, liquid and gas - encountered in everyday life. Or, at least, in the life of a typical French person, for most of these practical interrogations revolve around what goes on in the kitchen or at the table - from what happens when a buttered baguette is dipped into coffee to the structure of meringue. It is not surprising that the cultural obsession with matters culinary has recently resulted in the creation of a research laboratory, at the Collège de France in Paris, dedicated to 'molecular gastronomy'.

Jensen next explains how physicists have tried, with varying degrees of success, to explain the intriguing behaviour of everyday items by 'reconstructing' them from their basic components (the atoms). Toothpaste, water, glass and chocolate all undergo complex and schizophrenic transformations - oscillating between one state and another - depending on external conditions. And Jensen shows how the explanations physicists came up with have had a profound philosophical influence on our current view of matter.

Even today, one aspect of the philosophical debate is whether this 'reductionist' idea of matter is needed to understand the everyday world. Jensen's view is that the fundamental laws governing the interaction between particles at the most intimate level (inside atoms) are not necessarily relevant when explaining the macroscopic world. And he rightly argues that, for any specific example, each level of complexity should be treated separately - for instance, we should not systematically try to explain the macroscopic properties of a material in terms of its quantum mechanics. Although certainly logical in the physical sense, such controversial ideas are not particularly constructive - and are probably not in line with the open spirit of the Cafés des Sciences. They will surely raise a few eyebrows, especially among the particle-physics community.

Jensen then goes on to describe the tricks and tools that physicists use to infer the macroscopic behaviour of a physical system from the supposedly well-known microscopic behaviour of its components. And he gives everyday examples of the physical properties (mechanical, optical, electrical) shared by all materials. He also shows how certain classes of familiar materials - such as steel, plastics, foams and adhesives - have influenced the development of materials science and puts current research interests in context.

The final part of the book, which I found by far the most entertaining and instructive, offers a superb guide to what the author and his fellow physicists actually get up to in their mysterious laboratories. It reveals physicists as normal human beings, and explains why their search to understand matter makes them hide away from the outside world with their sophisticated and expensive pieces of equipment. To the general public, physicists can seem like alien beings, wasting extravagant amounts of taxpayers' money on useless experiments. This part of Entrer en matière should make such readers think again.

For a book that aspires to familiarize the person in the street with the latest developments in science, it's a pity the presentation is so dull - the only colour pictures are on the cover. This may make it less attractive to the wider audience that its accessible writing deserves.

I warmly recommend Entrer en matière to anyone (but especially physicists) even remotely interested in discovering more about matter. The book would serve as a perfect introduction to a first-year physics course - especially in French universities, where the material covered is more often about theory than the understanding of physical concepts. I only wish that such a book had been available in my student days.

I hope that this enlightening book, written by someone with such enthusiasm for communicating his knowledge, will be translated into other languages. It could then fulfil its ultimate aim of promoting interaction, communication and debate between scientists and the rest of the world.

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