Science

Is this the cleverest man in the world?

He won a Nobel prize, but since then his interests have widened. Now he's on a quest for a real Theory of Everything

Murray Gell-Mann has been described as The Man With Five Brains and it's not hard to understand why. He is an emeritus professor of physics, an international advisor on the environment, an authority on the origin of languages, arms control and foreign relations oh yes, and he has a Nobel prize for solving a key mystery of the universe.

Despite his sprite-like appearance, he also has a reputation for dealing with fools the way a killer whale deals with penguins. But then, it cannot be easy being The Man With Five Brains in a world with more than its fair share of Men With Half A Brain.

Pausing in London to talk to Focus about his new book on the science of (almost) everything, he pulls out a slip of paper he has been given in a major London bookstore. It shows that his book The Quark and the Jaguar has been classified under "Fiction - General", and the author as "Mann, M. Gell" .A review in the Sunday Times spells his name Gell-Man."

For someone who spends his time thinking about subjects most people cannot even spell, it must all be a bit wearing. But he has had time to get used to it: the fact is Gell-Mann has been a prodigy almost all his 65 years.

Born in New York at the start of the Great Depression, Gell- Mann's intellectual childhood was dominated by his father, an , Austrian immigrant who struggled to keep his family out of Skid Row. It was from him that Gell-Mann gained a fascination for science and mathematics.

Gell-Mann junior decided to teach himself calculus, the mathematical technique for calculating the effects of varying values. There were problems, however: I had a textbook by Sylvanus P Thompson, but I didn't like the way he dodged some important issues, like the concept of a limit," he recalls. But then, Thompson was merely a Fellow of the Royal Society , and Gell-Mann was all of seven years old.

It can't be easy being the Man with Five Brains in a world with plenty of Men With Half A Brain

Still just 15, Gell-Mann went to Yale. Curiously, his original plan had been to study linguistics or archaeology: despite his original enthusiasm, he found school physics, with its dreary lists of laws and seemingly unconnected disciplines, insufferably dull. His father, fearful for his son's employment prospects, wanted him to study engineering. As a compromise,Gell-Mann took physics. Brilliant teaching opened Gell-Mann's eyes to the esoteric delights of theoretical physics, and he went on to secure a PhD from the Massachusetts Institute of Technology in quantum theory, the physics of the subatomic world.

Still in his early 20s, Gell-Mann solved a key mystery about the quantum realm: why did some unstable particles then being found in particle accelerators disintegrate much more slowly than scientists expected? Gell-Mann found the answer by invoking the idea that particles possessed "strangeness" , a fundamental new property of matter to go with more familiar ones, like electric charge, and mass.

This breakthrough led to the idea for which he is most famous. During the 1950s and early 1960s, scientists were discovering more and more "fundamental" particles, with bizarre names like the Sigma and Xi. As the situation became more perplexing, the suspicion arose that there must be an underlying order in the subatomic menagerie.

In 1962 Gell-Mann had glimmerings of that order. The newly found particles seemed to fall into neat patterns, dictated by how much strangeness and electric charge they had. Intriguingly , one of the patterns appeared to have a particle missing. Surely , Gell-Mann reasoned, Nature would not spoil these beautiful patterns by leaving out a particle. He therefore calculated what the missing particle's properties should be, including its mass. Sure enough, in 1964 experimentalists using particle accelerators found the particle - the Omega-minus - with nearly exactly the mass predicted.

Only obeying order Trusting only in Nature's order, Gell-Mann calculated the mass of a "missing" particle. When it was found (in an experiment like the particle collision, right), his prediction was shown to be less than half a per cent out

It was a major triumph for Gell-Mann, yet it raised an obvious question: why did those patterns exist? Again, he supplied the answer: inside the Sigma and similar particles were even more fundamental particles, different combinations of which give the particles their unique properties.

Gell-Mann called these sub-subatomic particles "quarks" a nonsense word rhyming with "walk" Later he found the same word in James Joyce's Finnegans Wake thus guaranteeing him a lifetime of irritation, as even textbooks persistently claim that he lifted the word from "Finnegan's Wake", and that it rhymes with "park".

Even more annoying has been the claim that he did not even believe in quarks. "I always believed they were real - I just said that they had such strange properties that they were better stuck away where they can't be seen," he insists. "But I didn't know that one could find them inside particles."

There, at least, the experimental physicists had a surprise for him: by blasting high-speed electrons into hydrogen atoms, they have succeeded in detecting quarks lurking inside their host particles like tiny nuggets. In 1969 Gell-Mann's work on subatomic particles was rewarded with a Nobel Prize in physics - one of only six given unshared to a scientist in the last 25 years. "I did feel a little embarrassed that I should have been selected alone," he admits, adding puckishly. "The award did not mention quarks - I could still get one for that!"

Since winning the award he has continued to make major contributions to the understanding of subatomic particles. In the 1970s he played a key role in creating the theory that explains how quarks and the so-called "colour force" between them prevent the hearts of atoms flying apart. "Colour" like "strangeness", is a whimsical term given by scientists to the abstract mathematical and physical properties of particles.

More recently , he has become a vocal supporter of a controversial theory that some physicists think may account for all the forces and particles of the universe known as superstring theory, it is based on the idea that all of physics is ultimately the result of vibrations of "super- symmetric strings": bizarre, multidimensional entities far smaller than the smallest particle.

The real Theory of Everything will come from the study of how complexity arises from simple elements

Gell-Mann suspects that applying this theory to such mysteries as how the universe was born will produce major breakthroughs."To those thinking of a career in physics I would recommend that they try to work on joining super-string theory and cosmology."

He does not, however, call superstring theory a "Theory of Everything", as some physicists have dubbed it. "That is a misleading characterisation, unless "everything" is taken to mean only the description of the elementary particles and their interactions." What the ingredients of a true Theory of Everything might be is the subject of his new book.

Covering an astonishing range of subjects, The Quark and the Jaguar gives an insight into what the other four brains of Gell- Mann have been up to. Essentially , it describes how phenomena around us - a child learning to speak, the behaviour of an economic system - emerge from more simple elements. According to Gell-Mann, our world is made up of simple elements like quarks and "complex adaptive systems", which he describes using the metaphor of that sophisticated, mysterious beast, the jaguar.

Understanding , "emergent complexity" has become one of his great passions, leading him to become a founder of the Santa Fe Institute in California, where like-minded scientists ponder the emergence of everything from language to life itself.

Maybe such questions are too big even for Gell-Mann. Some scientists think all the talk of emergent behaviour and complexity theory is just jargon for quarter-baked ideas with little chance of becoming even half- baked. But this doesn't faze Gell-Mann. He seems simply to enjoy seeing where his mental powers will take him next.

"I've just got back from recording birdsong," he says. Where - near his home in Santa Fe? Of course not: "In Bhutan." And then suddenly we have it - the Man With Five Brains reveals his secret. "I don't know what spare time is."

Robert Matthews.

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