Inward Bound: Of Matter and Forces in the Physical World
by Abraham Pais
Oxford University Press (Clarendon Press), 666 pp., $24.95
Inward Bound is a sweeping narrative of the history and present state of atomic physics. It is something of an official history, explaining what, in the opinion of the physics community, is known, and how it came to be known. Pais was a distinguished participant in a number of the events he describes, but he distances himself from them. His erudite chronology is written from a deep love of the subject, a desire to make it intelligible, and a zest for describing the actors in his story. You could use this book to learn physics in the order that the discoveries became established. According to one school of pedagogy, that is the best way to understand the problems and the prospects of the discipline.
So it is a wonderful book, but for whom? It is superb for apprentice or journeyman physicists who want to hear, from a master colleague, about the stages in the evolution of their craft, as seen from inside the trade. But what is in it for anyone else, for most readers of The New York Review, for example? Open it at random and you will find equations that look quite daunting.
Inward Bound is not quite as hard as it may look. For most of the book, the equations are more or less intelligible to someone who is not embarrassed by the applied mathematics now taught to sophomores at run-of-the-mill colleges (or, to put it differently, expected of entering freshmen at Caltech). But only halfway through Pais interrupts himself to say: “At this point the reader may like to have at hand a simple but good book on quantum mechanics (like the one by Schiff) where results merely stated here and in the rest of this section are derived in detail.” Schiff wrote in 1949 for graduate students in physics, even if by now his material is known to a Caltech undergraduate by the end of the first year. So why should the rest of us have to read this highly touted book that has an average of one mathematical formula per page?
Because, although demanding, it is the best book about the history of physics that is both sophisticated and accessible, and that tells what the world is made of, and how we are finding that out. Had you scratched a metaphysician of long ago and asked what the universe is, as likely as not you would have been told about space, time, causality, and substance. Those are also the most memorable topics of physics, but until Pais, most general writers told us only about the first three.
Everyone knows a little about all four because of the vast upheavals in their very definitions that have occurred in this century. Relativistic thinking put paid to stable ideas about space and time. Among the lesser effects of quantum theory are gaping holes in old ideas about causality. And substance, contrary to the old metaphysicians, is not stable. Atoms are no longer indestructible, and interactions in the …