The Magnetic Universe: The Elusive Traces of an Invisible Force , J. B. Zirker
Johns Hopkins U. Press, Baltimore, MD, 2009. $70.00, $35.00 paper (542 pp.). ISBN 978-0-8018-9301-8, ISBN 978-0-8018-9302-5 paper
Plasma astrophysics, which includes space-plasma physics and solar physics, has flourished since the middle of the 20th century, roughly coinciding with the beginning of the space age. Instruments on spacecraft allow us to directly measure the properties of plasmas within our own solar system and to observe astrophysical plasmas remotely in parts of the electromagnetic spectrum that are not accessible from the ground. The wealth of data gathered by ground- and space-based instruments has led to a vast number of discoveries of beautiful, but also very complex phenomena.
In his book The Magnetic Universe: The Elusive Traces of an Invisible Force, Jack Zirker takes the reader on a journey through the cosmos, starting with a look at terrestrial magnetism and ending with magnetic fields that are generated at cosmological scales. Zirker, an emeritus astronomer at the National Solar Observatory, devotes approximately the first half of the book to descriptions of planetary and solar phenomena in our own solar system. In the rest of the book, he discusses the importance of magnetic fields to star formation and for compact objects, galaxies, and galaxy clusters. Zirker summarizes the history of the topics presented in each chapter and includes brief descriptions of more recent research developments and of some of the researchers involved in them.
Written in a clear, readable style, the book should be accessible to anyone with a high-school or college background in physics or astronomy. In the main text, no mathematical equations are used, and even in the notes at the end of the book, few are found. The chapters’ capsule histories and brief summaries of recent research add to the book’s liveliness. Although the material is complex, the author does an admirable job conveying to the reader the excitement and enthusiasm of the researchers for their work, even as they struggle to understand it.
Although I generally like the book, in some cases, additional figures would help readers better understand the text. Moreover, I am puzzled by the book’s utter lack of color images. There are so many stunning ones that illustrate the beauty of the objects we study in plasma astrophysics, it’s a pity that some were not used. For example, in chapter 7, “The Planets,” Zirker describes, but does not show, images of Jupiter’s and Saturn’s magnetospheres taken by the Magnetospheric Imaging Instrument aboard the Cassini spacecraft. Whatever the reasons were for using only grayscale images, the lack of color, in my opinion, represents a wasted opportunity to make the book more appealing.
Another point of criticism is that the book contains a fair number of typographical and factual errors, such as in the names of researchers and in identifying their institutions or nationalities. One name is repeatedly given incorrectly: University of Glasgow astrophysicist Peter Sweet, of the famous Sweet-Parker reconnection model, is consistently called Paul Sweet. In another example, the three-dimensional model of magnetic reconnection that is attributed to Eric Priest and Terry Forbes in a figure and in the text is actually not their model; although the figure is on the cover of their book Magnetic Reconnection: MHD Theory and Applications (Cambridge University Press, 2000), it is taken from a simulation by Klaus Galsgaard and Åke Nordlund of the University of Copenhagen.
Also, Zirker discusses some recent research developments in a way that is debatable. For example, in chapter 5, Zirker discusses only resonant absorption as a means of how the energy of Alfvén waves could be dissipated and contribute to heating the solar corona; other possible mechanisms, such as phase mixing, are not mentioned at all. However, I can understand that Zirker had to make choices regarding what to include and what to leave out, given that the book is intended for the general public and is not a scientific review or textbook.
Despite those complaints, I thoroughly enjoyed reading the book and would recommend it to anyone interested in learning about the importance of magnetic fields in the universe.
