*Black Holes: The Membrane Paradigm.*Kip S. Thome, Richard H. Price and Douglas A. Macdonald, eds. Yale University Press, New Haven, CT, 1986. 367 pp., illus. $40 HB, $14.95 PB.

*Black Holes: The Membrane Paradigm* treats a black hole as an object completely described by the properties of its surface. The surface is regarded as a membrane of fluid endowed with familiar physical properties such as electrical conductivity, viscosity, temperature, entropy, and so on. The values of these physical properties are simple and are prescribed by general relativity. The interaction of the black hole with the external universe is described in the book by the familiar laws of physics for such a fluid. The strength of this approach is that if you are familiar with only the nonrelativistic laws of physics, you can understand the behavior of black holes using all your intuition from the nonrelativistic laws. The formalism is exact outside the black hole, so that you can even do quantitative calculations for complex astrophysical situations.

The book represents a collaborative effort—its eight separately authored chapters are based on research done by the editors and six of their contemporaries at other institutions. Despite the separate authorships, *Black Holes* is written with two distinct threads: in one, the membrane formalism is derived from the standard treatments of black holes. In the other the formalism is used to describe many fascinating aspects of black holes.

It is this second thread that will be accessible to anyone with a good knowledge of nonrelativistic physics. The topics treated include: charged and rotating black holes; thermodynamics, including the origin of the entropy of black holes with their surroundings; black hole models for producing astrophysical jets. The extraction of the rotational energy of a black hole by the Blandford-Znajek process is also treated in some detail.

The writing is a masterpiece of pedagogy. Each new idea is carefully illustrated by a set of model problems worked through in detail—the editors' way of building up the physical intuition considered so central to the membrane paradigm. The book is a must for anyone seriously interested in black holes.