At the time of publication of this book, there was growing interest in how to formulate quantum field theory in spactimes with curved metrics with the intent of studying to what extent a non-flat curvature would change the properties and behavior of quantum fields as compared to the Minkowski case.The authors give an introduction to this research and they do a good job in that regard. Due to the influence of superstring and M-theory on high energy physics at the present time, fewer researchers are studying the problems as they are cast in this book. On the other hand, interest in the Casimir effect and the behavior of quantum fields at boundaries is still very much alive. This book could still be use to motivate this research. It is expected that anyone reading this book will have a background in quantum field theory in flat space, but one could still perhaps read it without such a background.

Quantum field theory in flat spacetime is difficult enough, and it is still not entirely understood from a mathematical perspective. Even the physics of interacting quantum fields is still poorly understood in flat spacetime, especially in its ability to predict a bound state. Therefore, it might seem a bit disconcerting to some for researchers to add further complications to quantum field theory by casting them in curved backgrounds. However, cosmological and astrophysical interests drives this research, as well as more practical considerations arising from the Casimir effect.

The renormalization procedures in quantum field theory are further complicated in curved spacetime via the "trace" or "conformal" anomalies. The reader gets a good dose of these in the book in the discussion on the renormalization of the stress. The idea of an "effective" action, which has been exploited with zeal in the flat spacetime case, appears here also. The most important thing to carry away from this book is that the idea of a particle in curved space quantum field theory is not very well-formulated, i.e. particle detectors in such situations are not related to the quantity of matter present in a region as they are in the flat-space case. Doing quantum field theory when gravity is present has instigated a huge amount of research, related to the still unsolved problem of just how to quantize the gravitational field.