**QUANTUM REFLECTIONS**

Edited by J. Ellis & D. Amati, Cambridge University Press, 2000; pp: 198, ISBN 0-521-63008-8 (hc); Price: 49.95.

The late CERN theorist John Bell had a keen interest in the foundations of quantum mechanics. His Bell inequality was a landmark contribution to the field. Therefore, when John Ellis and Daniele Amati decided to assemble a memorial book for John Bell, the foundations of quantum mechanics were an obvious theme.

The book comprises ten contributions, beginning with biographical notes by Mary Bell, who shared John Bell's life both as a spouse and as a scientific colleague. Roman Jackiw has contributed some reminiscences on his work with Bell, work that led to the Adler-Bell-Jackiw anomaly. John Magne Leinaas discusses accelerator-physics work he did with John Bell in the 1980s. All the other contributions are devoted to the foundations of quantum mechanics, in particular hidden-variable theories and Bell's inequalities. Roger Penrose discusses a mathematical aspect of the problem, whereas Alain Aspect reviews the experimental work. In between, one finds the contribution of Abner Shimony, where some theoretical questions are answered.

In a less specific fashion, Helmut Rauch reviews the experimental tests of quantum mechanics that were carried out by his group, using neutrons. This is an expanded and updated version of an article published by Rauch in Helvetica Physica Acta (vol. 61, 1988, p. 569). Gian Carlo Ghirardi explores possible extensions of quantum mechanics, obtained by adding nonlinear terms to Schrodinger's equation. Finally, David Mermin and Kurt Gottfried discuss the foundations of quantum mechanics at a more philosophical level, with extensive reference to John Bell's articles on quantum mechanics. The second article contributed by Kurt Gottfried was published in Physics World (vol. 4, October 1991, p. 34).

In most cases, the contributions are within reach of advanced physics undergraduates. One exception is Roger Penrose's chapter, which requires more advanced mathematical skills. The book would be especially valuable reading for undergraduate or graduate students who want to explore another facet of quantum mechanics, one that standard courses generally do not address. By and large, any physicist with an interest in the foundations of quantum mechanics should benefit from this book.

Claude Plante

Hull, Quebec