BOOK REVIEW / Functionals and flying fishes: Graham Farmelo on the scientist Murray Gell-Mann and the hunting of the quark: The Quark and the Jaguar - Murray Gell-Mann: Little, Brown, pounds 18.99

AN EXPERT in archaeology, anthropology, ecology, psychology, ornithology and linguistics, a speaker of 13 languages, winner of a Nobel Prize in physics - Murray Gell-Mann bears little resemblance to the caricature of a narrow-minded scientist. He has certainly done pretty well for someone who describes himself as 'fundamentally lazy'.

Over the last 40 years he has contributed prolifically to the theory of subatomic particles, at his peak writing an outstanding paper every few months. He is also well-known for introducing into the scientific lexicon several linguistically striking terms, most famously the 'quark'. This once referred to an agreeable type of curd cheese and a little-known coinage in Finnegans Wake ('Three quarks for Muster Mark]'), but in 1963 Gell-Mann used Joyce's word to name the new type of fundamental particle that he and a colleague at the California Institute of Technology independently proposed.

Experimenters have since verified that all matter, including every living thing, comprises a bundle of electrons and quarks, every one completely devoid of individuality (each electron and each type of quark is identical to every other in the universe). Meanwhile, some theoreticians believe that they are close to finding what they expect to be a comparatively simple theory that will describe, in just a few pages of mathematical hieroglyphics, the behaviour of all the fundamental particles and the forces between them.

But if everything is made of particles that are absolutely identical, how has the universe come to be so

diverse? This is one of the questions that Gell-Mann is now studying at the Santa Fe Institute, the interdisciplinary think-tank in New Mexico that he helped to found 10 years ago. He has also chosen this as the theme of his first book, whose title is taken from the poetry of Arthur Sze: 'The world of the quark has everything to do with a jaguar circling in the night'. This neatly captures Gell-Mann's belief that there are profound connections to be discovered between 'simple' theories of sub-atomic particles and the complexity of the world around us, symbolised by the jaguar, an astonishingly complex product of billions of years of evolution.

For someone so confident - some would say arrogant - Gell-Mann is surprisingly defensive in presenting this eagerly awaited work. He rues that writing has never come easily to him, and he thanks his wife, the poet and English professor Marcia Southwick, for helping to overcome his worst deficiencies of style and also for being 'ideal practice target': a reader who 'has not been trained in science or mathematics but has a profound interest in both'. To tackle a work of this depth and density, you do indeed need a profound interest in science (or at least in Gell-Mann), not just mere curiosity.

With little ado, he sets the scene by considering the technical meanings of simplicity and complexity (neither are simple, of course) and he introduces the key idea of a 'complex adaptive system', an ugly term that badly needs to be given a felicitous and engaging synonym. Such a system is one that learns or evolves in the same way as living systems do: it acquires information about its environment and condenses regularities in the information into a model or 'schema' which is used when the system acts in the real world.

This action feeds back to influence the competition among the competing schemata. Gell-Mann describes a wide variety of these systems - including a child learning a language, bacteria developing resistance to antibiotics and the behaviour of investors on stock markets - drawing fascinating comparisons between them.

The research programme outlined here could hardly be more ambitious: it is to find a single theoretical framework spanning the Big Bang right through to the evolution of human societies. The theory in prospect is 5 likely to focus on the continuous interplay between the simple fundamental laws and the operation of chance, which unavoidably arises in quantum mechanics, an essential ingredient of the laws. This is every bit as complicated as it sounds. As he hints, Gell-Mann's treatment of 'simple' physics is challenging to say the least, and will be easily digested only by the practised quantum mechanic and any others who are at home with 'decoherence functionals of coarse-grained histories'.

As we should expect from its polymathic author, the book is teeming with insights and intelligent comment, covering topics ranging from total quality management, to world environmental policy and reported observations of fishes falling from the sky. Yet, unlike so many accounts that aspire to deal with this range of material, this one is completely rigorous and refreshingly free of pseudo-spiritual twaddle (the God theory is given no space at all). But what a pity it is that Marcia Southwick and Gell-Mann's editors have allowed him so many indulgences, that his themes are more often than not obscured by the welter of his erudition.

In his preface, Murray Gell-Mann points out that the writing of a book is itself a complex adaptive system. The problem here is that in choosing his schema for the book, he didn't pay enough attention to the need to give it a strong and compelling narrative. As a result, I fear that in the competitive marketplace of popular science books The Quark and the Jaguar will, for all its strengths, suffer from the most brutal rigours of natural selection.