
Author(s)  Will, Clifford M. 

Title  Theory and Experiment in Gravitation Physies (2nd edition) 
Publisher  Cambridge University Press 
Year of publication  1993 
Reviewed by  Paul Blaga 
One of the crucial problems for gravitational theories, as well as for any physical theory, is their confrontation with experiments. But in order to do this, one needs some special working tools, allowing us to do several things: to analyse the highprecision results, to develop suggestions for future experiments, to compare and classify different theories (including general relativity) and to understand their consequences. It is the aim of this book to provide the reader with such a kind of tools.
The author introduce first the principles of gravitational theory and all the necessary informations in order for the book to be as selfconsistent as possible. The second part of the book is devoted to the socalled Parametrized PostNewtonian (PPN) formalism, worked out by the author and his collaborators in the late 60th and early 70th and including, as particular cases, the postNewtonian limit of general relativity and of other metric theories of gravitation. Then he use this formalism to analyse different tests, not only the classical ones, but also tests related to preffered frame or preffered location.
The PPN formalism is appropriate for the weak field, slow motion approximation. It doesn't work when dealing with compact objects, or the Universe as a whole. The following four chapters of the book are concerned with these new arenas for testing, including gravitational radiation, compact objects, binary pulsar, cosmological tests. The last chapter of the monograph has been added for this second edition and records the most significant results in the testing of gravitational theories obtained in the last decade.
In the moment when the first edition of the book has been published (1981, Cambridge University Press), this book was the only in the world wide literature (so far as I know) to make justice to this part of gravitational theory. In the meantime the situation didn't change, although now there are available some monographs related to the testing of general relativity (e.g. Soffel  Relativity in Astrometry, Celestial Mechanics and Geodesy, Springer, 1989), but none has its generality. The value of Will's monograph has been highly recognized and, without any doubt, it belongs to the small class of books fundamental for gravitational theory, beside "Gravitation" of Misner, Thorne and Wheeler (Freeman, 1973) or "The large scale structure of spacetime" of Hawking and Ellis (Cambridge, 1973). The book is an essentially reading for any worker in gravitation. Its level is graduate / research and it is suitable for use as reference book for a general course in gravitation or as a textbook for an advanced course.
The book is provided with a comprehensive list of references and another list refers to the new chapter added for the second edition. The index contributes, also, to the completion of the high level of the book. To finish, let me say that the first edition of the monograph is, also, available in Russian (Atomic Energy Press, Moskow, 1985).