Conceptions of Cosmos: From Myths to the Accelerating Universe—A History of Cosmology , Helge S. Kragh , Oxford U. Press, New York, 2007. $70.00 (276 pp.). ISBN 978-0-19-920916-3
In 1882 the philosopher John Stallo pooh-poohed theories that purported to apply physical and dynamical laws to the entire universe. But attacks on cosmology as unscientific did not end in the 19th century. In Conceptions of Cosmos: From Myths to the Accelerating Universe—A History of Cosmology , Helge Kragh cites (page 249), in addition to Stallo, a prominent British astronomer, Mike J. Disney of Cardiff University, who wrote in 2000 that the “most unhealthy aspect of cosmology is its unspoken parallel with religion. Both deal with big but probably unanswerable questions. The rapt audience, the media exposure, the big book-sale, tempt priests and rogues, as well as the gullible, like no other subject in science.”
Kragh, however, is less interested in dissecting the arguments of cosmology’s critics than exploring what he sees as the remarkable achievements of natural philosophers and scientists who have tackled cosmological questions. The author, a professor of history of science at the University of Aarhus, Denmark, is well known for his range of works on the history of physics and cosmology. Most of them, such as Cosmology and Controversy: The Historical Development of Two Theories of the Universe (Princeton U. Press, 1996) and Quantum Generations: A History of Physics in the Twentieth Century (Princeton U. Press, 1999), are centered on the 20th century. In Conceptions of Cosmos, Kragh goes farther afield. The book is focused chiefly on the history of cosmology in the Western tradition since ancient times. It is a skillful mix of narrative and analysis that draws on a very large collection of literature, including a significant body of work by Kragh himself.
The book is divided into five main chapters, each treating a distinct time period. In the first, Kragh covers ancient cosmologies to the Copernican revolution. He identifies the second period as the one in which Isaac Newton’s theory of universal gravitation held sway; it stretched from the late 17th century until the advent of Albert Einstein’s general relativity.
For Kragh, Einstein’s invention of general relativity, covered in chapter 3, was pivotal, and most of the book is devoted to developments after its creation. Kragh recounts, for example, how the meshing of general relativity with the observations of the redshifts of galaxies led to the establishment around 1930 of the expanding universe, surely one of the greatest discoveries in the history of science.
At the heart of the book is what Kragh calls the curious early history of the hot Big Bang model of the universe. He argues that it was proposed, largely independently, three times over some three decades. Although Georges Lemaître, on the strength of his primeval atom hypothesis of 1931, should, in Kragh’s opinion, be definitely viewed as the originator of Big Bang cosmology, it was George Gamow, Ralph Alpher, and Robert Herman who first developed the theory in a quantitative and physical fashion.
The next major elaborations of Big Bang theory came in the 1960s at the hands of Robert Dicke, James Peebles, and others; the 1965 discovery of the cosmic microwave background radiation by Arno Penzias and Robert Wilson earned them a share of the 1978 Nobel Prize in Physics. By the early 1970s, Big Bang cosmology had become much the dominant theory, and the steady-state model, a serious rival for two decades, had slumped to marginal status. In Kragh’s interpretation, by the mid-1970s cosmology was well on the way to becoming what Thomas Kuhn would have called a “normal” science, with its paradigm being the Big Bang model.
Kragh also describes recent concepts and observations, including the anthropic principle and the accelerating universe. He also takes a step back from his detailed narrative to consider some broader issues that run through more than one of the periods he describes, such as the problem of creation in cosmology. In a mere 276 pages he examines thousands of years of history. He must have encountered, then, numerous difficult choices of what to omit or include. Yet, overall, he has done an excellent job in keeping the reader’s attention on the big picture while providing enough detail to ensure that the discoveries and changes are intelligible.
Conceptions of Cosmos is aimed at a relatively broad audience, though some background in the physical sciences will be useful for the 20th-century sections. The book will certainly be enjoyed by working scientists and historians of science; its superb overview of the history of cosmology is unrivalled in terms of reliability and range of coverage.
