The Primordial Density Perturbation: Cosmology, Inflation and the Origin of Structure by David Lyth and Andrew Liddle, Cambridge University Press. Hardback ISBN 9780521828499, £40 ($75). E-book ISBN 9780511536922, $60.
In the early 1990s, the discovery of minute inhomogeneities in the temperature of the cosmic microwave background (CMB) marked the beginning of an observational endeavour that continues today thanks to dedicated satellite missions, such as the Wilkinson Microwave Anisotropy Probe and Planck. Current observations seem to suggest that the CMB anisotropies and polarization stem from inhomogeneities of the spatial curvature, which are related via general relativity to the fluctuations of the energy density. The latter fluctuations are often called, in the jargon, density perturbations. This monograph by David Lyth and Andrew Liddle unveils the different facets of the interplay between density inhomogeneities, quantum field theory and observational astrophysics. It follows (and partly overlaps with) Cosmological Inflation and Large-Scale Structure, written less than nine years ago by the same pair of authors.
The Primordial Density Perturbation is organized into three parts. The first and second parts provide a swift reminder of concepts connected to relativity (both special and general) and the Standard Cosmological paradigm (sometimes dubbed the ΛCDM model where Λ stands for the dark-energy component and CDM is the acronym for cold dark matter). The third part of the book, titled "Field Theory", collects all of those aspects of quantum-field theory that are germane to the evolution and normalization of cosmological perturbations. The section's main focus is organized around the description of space–time geometry in its most relativistic regime, i.e. when the typical wavelengths of the fluctuations in the spatial curvature are comparable with the Hubble radius, whose size is a million times larger than the extension of a typical spiral galaxy, such as the Milky Way.
Despite the excellent effort made by the authors, it seems necessary – especially for students and novices – to keep other dedicated books about quantum field theory on hand as well as books about cosmology (appropriately quoted through the 29 chapters of the text), such as the monumental Cosmology by Steven Weinberg (Oxford University Press 2008, CERN Courier May 2009 p43) and the reference treatise of the early 1990s Principles of Physical Cosmology by Jim Peebles (Princeton University Press 1993).
The rich literature that is flourishing these days on the mutual interplay between the microphysics probed by particle accelerators and the macrophysics scrutinized by astrophysics and cosmology suggests an increasing interest in these themes among a community that ranges from undergraduate students to skilled practitioners of the field. The different treatises are in agreement on one aspect: the unknown territory to be charted by the LHC will influence not only the forthcoming path of particle physics but also the development of cosmology and high-energy astrophysics during the next two decades.
Massimo Giovannini, CERN and INFN (Milan-Bicocca).
First Principles, The Crazy Business of Doing Serious Science by Howard Burton, Key Porter Books. Paperback ISBN 9781554701759, $24.95.
Science, usually an also-ran in the major funding stakes, is nevertheless occasionally surprised by generous benefactors. Just before the Wall Street crash in 1929, the Bloomberger family sold their department store to Macy's of New York and altruistically invested the proceeds in what would become the Institute for Advanced Study (IAS), Princeton. This was not to be a university, and its research would not be dictated or contracted. With mathematical science high on its agenda, early members included Albert Einstein, John von Neumann and Kurt Gödel.
The IAS soon became a template for other research centres, both in the US and abroad. One of these was Israel's Weizmann Institute, whose initial benefactors were the Sieff family, from another retailer, Britain's Marks and Spencer. Another was India's Tata Institute, supported by the mighty eponymous industrial combine. More recently came the foundation established by the Norwegian-American innovator Fred Kavli.
Another fresh venture is the Perimeter Institute (PI) for Theoretical Physics in Waterloo, Ontario, established in 1999 by Mike Lazaridis, co-founder of Research in Motion, the developers of the ubiquitous BlackBerry handsets. Lazaridis thrust an unsuspecting Howard Burton into the role of PI's first executive director, with the job of getting the new institute up and running. This book is Burton's memoirs of those heady days.
After labouring towards a PhD in theoretical physics, and with financial organizations snapping up numerate scientists, in 1999 Burton started looking for a job. The covering letter for his CV concluded with the line: "Please help save me from a lucrative career on Wall Street." One CV went to Research in Motion. To Burton's surprise a prompt and enthusiastic reply came from Lazaridis, who had an idea at the back of his mind and was looking for help to make it crystallize. Burton vividly conveys the difficulties of trying to sound enthusiastic in an interview for a job he didn't even begin to understand.
Nevertheless, he was hired. To clarify his own ideas, he went far and wide to explore possibilities and seek out recruits. One early candidate was Roger Penrose at Oxford, whose foreword to the book is characteristically stimulating and enigmatic by turns. There is a hilarious anecdote about trying to make a telephone call from Penrose's office. Another amusing episode comes when Burton goes to ask his former teacher at Guelph University to join the board of the new institute. On arrival, Burton is wrong-footed by being offered a postdoc position, which he immediately has to turn down and instead make his counter-offer to an even more surprised former teacher.
Soon, Burton was seeking other recruits and looking for suitable premises. With the first physicists in residence, attention turned towards establishing a working environment. Burton's initial confusion was now inherited by scientists unused to Lazaridis' work style. Burton's chapter, "The trouble with physicists", illustrates the culture shock when the brash commercial world meets the passive serenity of academia. Commendably, outreach was soon identified as a major objective at PI, with a successful series of public lectures and other events.
The book's "crazy" subtitle and the offbeat cover illustration could be misleading: at first glance it is easy to assume that the book is eccentric. However, its informal style masks serious issues. PI aims to redress the balance in a world dominated – culturally, intellectually, technologically and economically – by scientific research, but which is nevertheless largely uncaring and unappreciative of the importance of science.
Because PI is an institute for theoretical physics, theorists especially will enjoy the book, and many well known figures flit across the pages. There is no official collective noun for theoretical physicists, but Burton's acknowledgements include a list of about 200 of them, which surely qualifies for one ("galaxy", "group", "resonance"?).
Gordon Fraser is editor of The New Physics for the 21st Century, recently reissued by Cambridge University Press in paperback.