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Relativity and cosmology
catalogs, even though the abbreviations BD, CD and CPD are used without explanation in the text. Yet there is a listing for teZescopeand a rather unhelpful explanation for KSS, which is not mentioned anywhere in the text. Some definitions are so poorly worded as to become illogical. And some definitions are very narrow or even basically flawed (e.g., heliacal rising/setting, planetary precession, vignetWI. A list of references, affected by an unfortunately large number of misspelled names and wrong initials, and a short but generally adequate index complete the book. A strength of the book derives from the author’s status as something of an outsider in the field of astrometry, for alerts are given on a variety of potentially troublesome practical points that experts tend to pass over. Yet Taff has done his homework well, and consulted some of the right people, in developing his own competence in a difficult and complex area. The information directly related to the GEODSS assignment seems to have passed successfully through the ultimate test of practical application. But the reader is advised to be a bit wary about information and advice in peripheral areas. Elizabeth Roemer
Relativity and Cosmology Jayant V. Narlikar 287~~. Macmillan Co., N.Y. 1979. “Scientific enquiry proceeds on the premise that no theory is perfect” (from the preface). Even non-perfect theories, however, must be studied in a perfect way. This book by Narlikar is intended to serve this end. It is based on the lecture course the author gave in the graduate school of the Tata Institute of Fundamental Research in Bombay. There are two different approaches in textbook presentations of General Relativity: traditional, when “the space-time is described by four coordinates and all the physical and geometrical quantities are studied in terms of these coordinates ,” and modem, which “aims at looking at the intrinsic properties of space-time using, as far as possible, coordinate-free techniques” (p. 9). This book is written in the traditional approach. This, of course, does not detract from the book, since a few generations of excellent physicists have learned their trade from similar traditional textbooks. One historical error should be mentioned here, however. On page 198 one reads that Eddington and Lemaitre independently suggested that by considering a world model with the value of the cosmological constant slightly larger than that of Einstein’s static universe, one obtains a model which explodes at the beginning, approaches the quasi-static states, and then expands again. Historically, this is not true. The model was constructed and popularized by Lemaitre alone. Eddington
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strongly opposed such a picture of the cosmic evolvtion because of its singular beginning. The model investigated by both Eddington and Lemaitre (and usually called Eddington-Lemaitre world model) starts its evolution asymptotically from the Einstein static state. This mistake should be corrected in future editions. The book, nonetheless, seems well suited as an introduction or review of the fundamental notions of relativity and cosmology. hf. Heller The Milky Way
Bart J. Bok and Priscilla F. Bok 356~~. Harvard University Press, Cambridge 1981, $20.00 This book is a revision and an update of the classic non-technical introduction to the structure of our galaxy. Since the last edition was published in 1974 major strides in galactic structure have been made. The authors discuss these complex and disparate phenomena such as the formation of spiral arms, processes in an active galactic nucleus, tidal break-up of star clusters etc., in a cogent and thoroughly readable manner. The text is copiously illustrated; it contains 13 1 photographs and diagrams. Their presence is very helpful in following the basic text. I would recommend this book most highly to any intelligent layman interested in astronomy. J. C. H&don The Physics of the Interstellar
Medium
J. E. Dyson and D. A. Williams 194~~. Wiley & Sons, New York etc. 1980, $24.95 This work was written to serve as a basis for an undergraduate physics course in astrophysics. The topic of interstellar medium was chosen because it illustrates well the breath of underlying physical disciplines necessary for the understanding of astrophysics. The authors emphasize the applications of physics and do not claim to have,presented a complete picture of the interstellar medium. The 186 pages of text are divided into eight chapters: introduction, how information is obtained about the intersettlar medium (spectral lines), microscopic processes (such as heating and cooling), interstellar grains, Strijmgren regions, gas dynamics (shocks), dynamical processes (such as stellar winds and supernova explosions), and a final chapter giving the present picture of the interstellar gas and star formation. Not all these topics are discussed equally. In view of the authors’ expertise they emphasize the dynamical aspects of the interstellar medium. They present very good discussions stressing the basic physics of stellar winds, expanding Striimgren regions, shocks, supernova explosions and cloud collapse. The reviewer felt that a chapter on cosmic rays would have been useful in stressing the underlying physics of the interstellar medium. This opportunity was missed by the authors as the discussion of cosmic rays would have been a good illustration of the application of special relativity and nuclear physics.
139
Relativity and Cosmology Jayant V. Narlikar 287~~. Macmillan Co., N.Y. 1979. “Scientific enquiry proceeds on the premise that no theory is perfect” (from the preface). Even non-perfect theories, however, must be studied in a perfect way. This book by Narlikar is intended to serve this end. It is based on the lecture course the author gave in the graduate school of the Tata Institute of Fundamental Research in Bombay. There are two different approaches in textbook presentations of General Relativity: traditional, when “the space-time is described by four coordinates and all the physical and geometrical quantities are studied in terms of these coordinates ,” and modem, which “aims at looking at the intrinsic properties of space-time using, as far as possible, coordinate-free techniques” (p. 9). This book is written in the traditional approach. This, of course, does not detract from the book, since a few generations of excellent physicists have learned their trade from similar traditional textbooks. One historical error should be mentioned here, however. On page 198 one reads that Eddington and Lemaitre independently suggested that by considering a world model with the value of the cosmological constant slightly larger than that of Einstein’s static universe, one obtains a model which explodes at the beginning, approaches the quasi-static states, and then expands again. Historically, this is not true. The model was constructed and popularized by Lemaitre alone. Eddington
138
strongly opposed such a picture of the cosmic evolvtion because of its singular beginning. The model investigated by both Eddington and Lemaitre (and usually called Eddington-Lemaitre world model) starts its evolution asymptotically from the Einstein static state. This mistake should be corrected in future editions. The book, nonetheless, seems well suited as an introduction or review of the fundamental notions of relativity and cosmology. hf. Heller The Milky Way
Bart J. Bok and Priscilla F. Bok 356~~. Harvard University Press, Cambridge 1981, $20.00 This book is a revision and an update of the classic non-technical introduction to the structure of our galaxy. Since the last edition was published in 1974 major strides in galactic structure have been made. The authors discuss these complex and disparate phenomena such as the formation of spiral arms, processes in an active galactic nucleus, tidal break-up of star clusters etc., in a cogent and thoroughly readable manner. The text is copiously illustrated; it contains 13 1 photographs and diagrams. Their presence is very helpful in following the basic text. I would recommend this book most highly to any intelligent layman interested in astronomy. J. C. H&don The Physics of the Interstellar
Medium
J. E. Dyson and D. A. Williams 194~~. Wiley & Sons, New York etc. 1980, $24.95 This work was written to serve as a basis for an undergraduate physics course in astrophysics. The topic of interstellar medium was chosen because it illustrates well the breath of underlying physical disciplines necessary for the understanding of astrophysics. The authors emphasize the applications of physics and do not claim to have,presented a complete picture of the interstellar medium. The 186 pages of text are divided into eight chapters: introduction, how information is obtained about the intersettlar medium (spectral lines), microscopic processes (such as heating and cooling), interstellar grains, Strijmgren regions, gas dynamics (shocks), dynamical processes (such as stellar winds and supernova explosions), and a final chapter giving the present picture of the interstellar gas and star formation. Not all these topics are discussed equally. In view of the authors’ expertise they emphasize the dynamical aspects of the interstellar medium. They present very good discussions stressing the basic physics of stellar winds, expanding Striimgren regions, shocks, supernova explosions and cloud collapse. The reviewer felt that a chapter on cosmic rays would have been useful in stressing the underlying physics of the interstellar medium. This opportunity was missed by the authors as the discussion of cosmic rays would have been a good illustration of the application of special relativity and nuclear physics.
139