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Mysteries of the solar system
Planet. Space Sci. 1969, Vol. 17, pp. 773 to 775. PergamonPress. Printed in Northern Ireland
BOOK REVIEWS
R. A. LYTTLETON: Mysteries of the Solar System. Clarendon Press: Oxford University Press, 1968. vi ÷ 261 pp. Hard cover 35s. THE AUTHOR, Fellow of St. John's College, Cambridge, and the publishers are known well enough to expect an interesting contribution, even if controversial, to the less known problems of the solar system. Based on a series of lectures given in America, the author offers the essays "as an introduction to the problems involved". Actually, it is a one-sided presentation of the author's own views which in most cases are difficult to defend, and in others are obviously wrong and can be beaten by his own arguments. Thus, 74 pages are devoted to the nature and origin of comets, proposed to be built currently from interstellar matter in the wake of the Sun. This mechanism of the "gravitational lens', first suggested by N61ke in 1910, could work in a primordial medium of a density 10 -1° g/cm 3, not at 10 -24 as the author wishes (pp. 152-154); he rightly wants the particles (of r = 10 a cm) to be focused within a cylinder of 106 cm at 100 times Jupiter's distance or 1016 cm, and agrees that the particle motions must be closely parallel but fails to carry the calculation further. The required angular deviations must be less than 10n/10 ~6 -- 10 -1°, or the transversal velocities less than 10 -a cm/sec! Even the Brownian motions in interstellar space, for particles of this size, would amount to 0' 1 cm/sec, and unequal radiation pressure by starlight would lead to very much greater dispersion in the particle velocities. The physics of comets is not only ignored but, on the 30 lines (pp. 142-143) dealing with it, ignorance is displayed; among spectral identifications, the molecule CO (not yet observed) instead of CO + is listed. This is not a printer's error--the author makes a point of it, pretending to compare the intensities of CO (the unobserved) and CO ~ at different distances from the nucleus and concludes that ionization is strongest near the nucleus, contrary to our elementary knowledge about cometary spectra. The decrease in the size of the coma at smaller heliocentric distances he explains by convergence of the heliocentric orbits of the individual meteoric particles, ignoring the fact that the observed fluorescent radiation belongs to gaseous C~ and CN, and that the photoelectric destruction by sunlight of these molecules renders them invisible the sooner the more intensely they are irradiated. Of the 189 notes which I made in reading about 60 per cent of the book, only 12 are positive or approving. Not all of the rest refer to as drastic shortcomings as those mentioned above (some nevertheless are), but essential and biased they are, little justice also being done to modern authors, while Leonardo da Vinci is cited at length. In concluding sentences, it is frequently stated that "we do not know", which in some cases may be philosophically justified, in others reflects only the ignorance of the author. Internal contradictions also appear in different places of the book. Some of the passages being written in a popular style, others in a technical language without proper definitions for the uninitiated, and with mathematics at an undergraduate level which is mostly correct except for some slips (e.g. a mix-up of accepted notations for a hyperbola on pp. 123, 129 and 148, where a is sometimes negative as it should be, sometimes positive)--it is difficult to define the proper circle of readers for whom it is intended. On my part, I learned nothing but one thing from i t - - t h a t books nowadays are published rather too easily. E J. OPIK
KRtSTEN FOLKESTAD (Editor): Ionospheric Radio Communications. Plenum Press, New York, 1968. xi + 468. $25.00. THis volume represents the Proceedings of a NATO Advanced Study Institute held at Finse, Norway, in April 1967, the full title of which was "Ionospheric Radio Communications in the Arctic". Most of the papers presented are concerned with the Arctic environment, but the omission of the relevant words in the title of the book has been justified on the grounds that contributions are included which describe novel techniques and advanced system refinements not particularly related to high latitudes. The NATO Institute, which was organized jointly by the Canadian Defence Research Telecommunications Establishment and the Norwegian Defence Research Establishment, aimed to bring together three groups of workers concerned with ionospheric radio communications: radio physicists (who study the physics of the propagation medium), design engineers (who design equipment and systems), and technical 773
BOOK REVIEWS
R. A. LYTTLETON: Mysteries of the Solar System. Clarendon Press: Oxford University Press, 1968. vi ÷ 261 pp. Hard cover 35s. THE AUTHOR, Fellow of St. John's College, Cambridge, and the publishers are known well enough to expect an interesting contribution, even if controversial, to the less known problems of the solar system. Based on a series of lectures given in America, the author offers the essays "as an introduction to the problems involved". Actually, it is a one-sided presentation of the author's own views which in most cases are difficult to defend, and in others are obviously wrong and can be beaten by his own arguments. Thus, 74 pages are devoted to the nature and origin of comets, proposed to be built currently from interstellar matter in the wake of the Sun. This mechanism of the "gravitational lens', first suggested by N61ke in 1910, could work in a primordial medium of a density 10 -1° g/cm 3, not at 10 -24 as the author wishes (pp. 152-154); he rightly wants the particles (of r = 10 a cm) to be focused within a cylinder of 106 cm at 100 times Jupiter's distance or 1016 cm, and agrees that the particle motions must be closely parallel but fails to carry the calculation further. The required angular deviations must be less than 10n/10 ~6 -- 10 -1°, or the transversal velocities less than 10 -a cm/sec! Even the Brownian motions in interstellar space, for particles of this size, would amount to 0' 1 cm/sec, and unequal radiation pressure by starlight would lead to very much greater dispersion in the particle velocities. The physics of comets is not only ignored but, on the 30 lines (pp. 142-143) dealing with it, ignorance is displayed; among spectral identifications, the molecule CO (not yet observed) instead of CO + is listed. This is not a printer's error--the author makes a point of it, pretending to compare the intensities of CO (the unobserved) and CO ~ at different distances from the nucleus and concludes that ionization is strongest near the nucleus, contrary to our elementary knowledge about cometary spectra. The decrease in the size of the coma at smaller heliocentric distances he explains by convergence of the heliocentric orbits of the individual meteoric particles, ignoring the fact that the observed fluorescent radiation belongs to gaseous C~ and CN, and that the photoelectric destruction by sunlight of these molecules renders them invisible the sooner the more intensely they are irradiated. Of the 189 notes which I made in reading about 60 per cent of the book, only 12 are positive or approving. Not all of the rest refer to as drastic shortcomings as those mentioned above (some nevertheless are), but essential and biased they are, little justice also being done to modern authors, while Leonardo da Vinci is cited at length. In concluding sentences, it is frequently stated that "we do not know", which in some cases may be philosophically justified, in others reflects only the ignorance of the author. Internal contradictions also appear in different places of the book. Some of the passages being written in a popular style, others in a technical language without proper definitions for the uninitiated, and with mathematics at an undergraduate level which is mostly correct except for some slips (e.g. a mix-up of accepted notations for a hyperbola on pp. 123, 129 and 148, where a is sometimes negative as it should be, sometimes positive)--it is difficult to define the proper circle of readers for whom it is intended. On my part, I learned nothing but one thing from i t - - t h a t books nowadays are published rather too easily. E J. OPIK
KRtSTEN FOLKESTAD (Editor): Ionospheric Radio Communications. Plenum Press, New York, 1968. xi + 468. $25.00. THis volume represents the Proceedings of a NATO Advanced Study Institute held at Finse, Norway, in April 1967, the full title of which was "Ionospheric Radio Communications in the Arctic". Most of the papers presented are concerned with the Arctic environment, but the omission of the relevant words in the title of the book has been justified on the grounds that contributions are included which describe novel techniques and advanced system refinements not particularly related to high latitudes. The NATO Institute, which was organized jointly by the Canadian Defence Research Telecommunications Establishment and the Norwegian Defence Research Establishment, aimed to bring together three groups of workers concerned with ionospheric radio communications: radio physicists (who study the physics of the propagation medium), design engineers (who design equipment and systems), and technical 773