The Bactra Review: Occasional and eclectic book reviews by Cosma Shalizi   27

Fragile Objects

Soft Matter, Hard Science, and the Thrill of Discovery

by Pierre-Gilles de Gennes and Jacques Badoz

Translated by Axel Reisinger

Copernicus Books, Springer-Verlag, 1996
Most of the universe, according to the astronomers, consists of something utterly unknown which we can't see, called ``dark matter.'' Most of the rest of the mass of the universe is found in stars, at temperatures where atoms have broken down into freely-moving charged particles, a state of matter called plasma. Cool plasmas and they become gases, which seem to take the next largest share of the universe. Everything that's left, everything that coheres, is lumped into one sub-discipline, ``condensed matter physics'' (condensed as compared to gases or plasmas). Condensed matter physics is itself split into two parts: the older one, ``hard'' condensed matter, a.k.a. solid state physics, deals with things whose spatial arrangement, at least at the level of molecules, is simple and fixed: crystals, essentially. It encompasses the conduction of electricity, magnetism, the whole of semiconductor theory, and a great many other useful subjects which always bored me to tears. Everything flexible, fluid or amorphous --- most of the interesting stuff in the world around us --- is ``soft condensed matter'', which has only really begun to be properly explored in the last few decades. Remarkably enough, the theoretical tools needed to understand its behavior, starting from molecules and working upwards, turn out to be exceedingly similar to those already developed for hard condensed matter and the theory of gases. Pierre de Gennes was one of the leaders in extending conventional statistical physics to liquid crystals (on which his monograph is still a standard reference), polymers, surfaces, etc., and for this important and elegant work he won the Nobel Prize for Physics in 1991. Now, I suppose there are probably people who manage to win a Nobel and not get deluged by requests to speak and write, but de Gennes was not one of them; in fact he was positively champing at the bit: ``I took to the road, armed with a set of slides under my arm'' (the last is one of the tell-tale signs of the hard sciences), touring French high schools, lecturing on the virtues of science (particularly the study of soft condensed matter), on research life, and on science education. Fragile Objects is based on the talks given to those high schools, and even retains a few question-and-answer sections.

The first part consists of puzzling and amusing phenomena in soft condensed matter (polymers, surfactants, liquid crystals, wetting, bubbles and surfaces), explained verbally and pictorially (no Feynman diagrams!), and demanding no more than a basic understanding of atoms, molecules and electricity to follow. It is good, after its kind --- i.e. the examples are genuinely interesting, the explanations correct and free of condescension and ``then a miracle happens'', the experiments described are both simple and clever (``the Benjamin Franklin spirit'', as he puts it) and they genuinely lead to larger issues --- but not outstanding. The second part is made up of de Gennes's reflections on the trials and rewards of a life in scientific research, illustrated by anecdotes of his own career. His considerations on when to switch fields are particularly interesting, not least because he's done it at least three times.

The third, and to my mind the most interesting part, contains de Gennes's views on science education in France (dismal), and what should be done to improve it (lots): ``When I welcome a freshman class at our Institute of Physics and Chemistry, I insist on concepts that most math majors are not at all familiar with.... This `reeducation' phase takes a minimum of two years. I am constantly astounded by how little common sense recently degreed engineers have.'' If de Gennes is to be believed, it is perfectly possible to obtain a physics degree in France having only the barest acquaintance with the inside of a laboratory, and no idea of how to do simple quantitative estimates or even Fermi problems --- but be letter-perfect in the properties of self-adjoint matrices. (His story of a Polytechnic graduate who, when faced with a perfectly straight-forward back-of-the-envelope problem, was reduced to crying, ``But, sir, what Hamiltonian should I diagonalize?'' is one I will use on my own students.) De Gennes blames the lingering influence of Auguste Comte, and, much more plausibly, the excessive importance of entrance examinations (which test, essentially, math), the conservatism and insularity of academic departments, especially at universities, and the unwillingness of French students (particularly those who have gotten into the better schools) to exert themselves or sully their hands. Prior to reading Fragile Objects, I hadn't thought that it was possible to do much worse at teaching than American physics departments; I am happy to see I was wrong.

Having won recognition for an exceedingly specialized contribution to human knowledge, the true content of which it takes a good many pages to explain, it was only natural that de Gennes's views be solicited on all manner of subjects, like the environment and ethics, and some of that material has made its way into Fragile Objects. These passages are entirely predictable and unoriginal, but he doesn't claim anything more for them, and they are mercifully short. There is some repetition between different essays, but not so much as to aggravate. The biggest error I found was the confusion, on p. 115, of The Romance of the Rose, a 13th century allegorical love poem, with The Name of the Rose, a 20th century allegorical detective novel.

This will make a fine book for libraries, particularly those used by high school students, but it's hard to see why anyone not obsessed by either Nobel Laureates or by soft condensed matter physics would buy this book, at least in hardcover.

189 pages, glossary of basic terms, index.
Condensed Matter / Physics / Popular Science
Currently in print as a hardback, ISBN 0-387-94774-4, US$24.00; first published as Les Objets Fragiles, Paris: Librairie Plon, 1994. LoC QC171.2 G4613.
10 November 1997