The physics of divorce, Dante, detection and erotic outburst

Abraham Pais's latest book serves as a poignant warning. What was meant to be a portrait gallery of outstanding contemporary physicists comes across as a rather piecemeal picture of some of the finest minds of our times. Clearly, Pais, a considerable physicist in his own right, has been in close contact with many of these personalities; equally clearly, extracts from his earlier work demonstrate that Pais has in the past written lucidly and profoundly.

Unfortunately, the latter qualities are almost totally absent from this book. It is a random collection of thoughts, expressed in language that ranges from the extempore to the almost vulgar, about individuals who are not all at the same level of excellence in the world of physics.

The reader is left with the impression of a hastily compiled set of speeches, expanded by quotations and extracts from CVs and seemingly embroidered by overly faithful transcriptions from an indistinct Dictaphone. This is an image that persists, despite the odd lapse into brilliance inspired by Pais's subject matter.

Not all the scientists that Pais discusses were or are geniuses, and not all the geniuses he discusses led interesting lives. This unevenness leads to some startling omissions, and some surprising inclusions. Also surprising is what Pais chooses to relate about his subjects. The banality of an episode where Pais describes Niels Bohr's bewilderment at trying to smoke an unlit pipe is a case in point. Jokes generally fall flatter in print than in person.

Pais also displays a strange reticence to enter into detailed descriptions of episodes, such as the feud between Chen Ning Yang and Tsung Dao Lee, or Paul Ehrenfest's suicide, that he is not too reticent to mention in the first place. The reader is left with an uneasy feeling that he uses such episodes to indicate his own importance in the lives of scientists more illustrious than himself.

Where the book does succeed is in its almost throwaway insights into the processes and the personalities of contemporary science. On the nature of scientific revolutions, Pais makes the point that the past is never entirely rejected in favour of the future: "The scientist knows that it is in his enlightened self-interest to protect the past as much as is feasible." The inclusion of Erwin Schrodinger (then 38) within the context of Knabenphysik (a term used to describe the heyday of quantum mechanics, where the main players were in their 20s) is ascribed by Pais to the effect of "a late erotic outburst".

Samuel Goudsmit, whose expertise on decoding spectra was to prove indispensable to George Uhlenbeck in formulating the theory of electronic spin, was a "wizard at cryptograms", thought "like a detective", and had, Pais informs us, taken courses in forensic work, as well as in deciphering hieroglyphics.

The duality of quantum mechanics is illustrated by a beautiful quote from Max Born: "The motion of particles follows probability laws, but the probability itself propagates according to the laws of causality." It is also interesting to find that the issue of who precisely should be given credit for a particular idea was as relevant for some of these great minds as it continues to be for lesser ones today. Born's chagrin at Bohr's dismissal of his probabilistic interpretations of quantum mechanics - "We never dreamt that it could be otherwise" - is palpable, as is Eugene Wigner's anger that Hermann Weyl pre-published him in the introduction of group theory to quantum mechanics.

The book also holds some surprises. Paul Dirac is far from the "pure" theoretician that his famous equation makes one imagine. His training in engineering is seen to be the reason for somewhat unexpected views: "The pure mathematician who wants to set up all of his work with absolute accuracy is not likely to get very far in physics."

The contrasting attitudes of Dirac, who asked a colleague who loved Dante:

"How can you do both physics and poetry? In physics we try to explain in simple terms something that nobody knew before. In poetry it is the exact opposite," and Viktor Weisskopf, who described his interest in the arts and his profession in science by saying "In the morning I turn from mystery to reality, in the evening I return from reality to mystery", provide an insight into the range of minds classified as purely scientific.

Unsurprisingly, many of the best scientists were renaissance men: Hendrik Kramers was a cellist, poet, translator and editor of a literary journal; Uhlenbeck introduced Enrico Fermi to Michelangelo's Moses in Vincoli , and would have become a historian had he and Goudsmit not discovered spin. John von Neumann's catholic interests were in another direction: apart from the mathematical foundations of quantum mechanics, he pioneered game theory, now of exceptional interest to economists and physicists alike.

Perhaps the most illuminating chapter is on Wolfgang Pauli, pioneer of the famed exclusion principle. It is full of memorable quotes from Pauli: "So young, and already so unknown," about a young man whose initiative exceeded his intelligence; about the United States: "It is easy to earn money here, but difficult to spend it in pleasant ways" - as well as insights into Pauli's fascinating private life (several marriages, bouts of alcoholism and psychoanalysis). This chapter illustrates the complexity of a genius of science. One only wishes that the rest of the book was of the same standard.

Anita Mehta is associate professor, S. N. Bose National Centre for Basic Sciences, Calcutta, India.