Middle World: The Restless Heart of Matter and Life

  • Mark Haw
Macmillan Science: 2006. 256 pp. £16.99, $24.951403986037 | ISBN: 1-403-98603-7

The fascinating tale of brownian motion has been looking for a story-teller for a long time. The tangled threads knot together, rather than begin, in the nineteenth century with botanist Robert Brown's original observations of the random, ceaseless motion of particles in pollen grains of Clarkia pulchella. The threads lead back in time to medieval theories of matter that tangled physics with theology — a pattern that ran deep through the work of Galileo and Newton — and further back still to the Epicureans. Going forwards from Brown, they twist through the nineteenth century's ambivalence towards molecular theory and the thermodynamics of Sadi Carnot and Lord Kelvin. Weaving through the kinetic theory of James Clerk Maxwell and the statistical mechanics of Ludwig Boltzmann that finally grasped the physics of randomness, they lead to the complementary beauties of Einstein's theory of brownian motion and Jean Baptiste Perrin's experiments that led to modern soft-matter physics and a new understanding of the role of brownian dynamics in molecular biology. This is a remarkable story of science and scientists that leaves no major science untouched and summons onto the stage a colourful and eminent cast from centuries of endeavour.

Jean Baptiste Perrin (above) provided a new understanding of Robert Brown's notion of random motion. Credit: ACADEMIE DES SCIENCES, PARIS/ARCHIVES CHARMET/BRIDGEMAN ART LIBRARY

In Middle World, Mark Haw provides an accessible and racy account that succeeds in opening up technical ideas without losing momentum. Haw is not insensitive to dramatic irony, and makes a satisfying conclusion out of the return of brownian motion to illuminate dynamical processes in biology, where it originated, after spending a century wandering the worlds of physics and physical chemistry. We fleetingly visit the role of brownian motion in polymer physics, oxygen capture by myoglobin, the protein-folding problem and the question of how molecular motors (the cell's cargo transporters) can possibly execute controlled and directed motion in a turbulent brownian world. It's not quite T. S. Eliot, but we are almost back where we began, yet knowing for the first time.

Although it is a fitting window onto a selection of hot topics in current science, the final 'contemporary' section drops the connected storyline of the preceding historical material. I wonder if the role of diffusion in the molecular biology of plant reproduction might have connected this coda more strongly to the earlier narrative.

The research is mostly thorough: Haw has picked up on subtleties often glossed over, such as the prescient role of Michael Faraday in advocating a correct reading of Brown's work, the correct early kinetic theory of the unfortunate John Waterston, who disappeared from science following its rejection, and the extraordinary timeliness of Einstein's molecular theory for the diffusion constant published earlier by the largely overlooked William Sutherland. But the reader has to stay alert — a cost of the narrative's unflagging pace is that people and places flash by all too quickly. I wish we had the time to get to know Perrin, and the shadowy figure of Brown himself, rather better.

Another aspect of the thirst for satisfying narrative is that history seems sometimes to be squeezed into the story's form, rather than the converse. So our sole representative of the middle ages is Hieronymous Bosch, whose portrayals of chaos conveniently prepare the stage for a sea change to order in the enlightened following act starring Galileo and Newton. The plot thickens with a return to calculated chaos in statistical mechanics, and so on. A case could be made more strongly for a highly ordered medieval theory of matter than for a chaotic one, and Galileo's corpuscular theory of matter in The Assayer in 1623 surely anticipates the underlying chaos of kinetic theory. But perhaps such complaints are churlish: a good yarn withers from too much of “on the other hand”.

Such strong selection in historical interpretation, as well as some under-development of character, could well be the results of zealous editing with a younger lay readership in mind. In places the author gives the impression that he would have liked to say more. Perhaps the ambiguity in target readership is also reflected in the uneven style, which alternates ambitious alliteration with colloquialism (it was my first non-fiction read containing, as an entire sentence, “Not.”). But these are pitfalls for all authors and publishers of 'popular science', and I would hope there is something for everyone in this highly enjoyable little book.