John Gribbin's Companion to the Cosmos is a large book, an encyclopaedia with an alphabetic listing of articles on every subject which as anything to do with the modern image of the Universe.
The scope of the subject is truly mind-boggling: in his long introduction, Gribbin speculates about the existence of many universes, all created in the Big Bang, but now isolated from one another. Gribbin uses the term "Cosmos" to include everything that is - and that includes our own Universe, the one we can examine most easily.
The main body of the book is the 417-page dictionary section. This is preceded by an introduction of 17 pages and followed by a section of Timelines, a chronological list which displays columns showing key dates in science, brief biographies of notable scientists and key dates in general history.
The introduction gives a potted outline of current views on the beginnings and development of the Universe that serves to set the scene for the feast of information that follows.
The dictionary covers a wide variety of topics, some of which are very short, while others, such as the article on black holes, are several pages long. All of the entries contain key words in bold text, allowing you to pursue a topic in further depth through a string of cross references.
The presentation of the information in the form of an encyclopedia makes it less easy to digest than an ordinary book, although it could be argued that this is a more appropriate way to present such an extensive subject and that any attempt to force a linear narrative on it would be artificial.
The style of the various articles is clear and, as far as I have checked, the facts are correct, although it is possible to quibble about some points. Gamma rays, for example, are said to be photons in the energy range from 10 KeV to 10 MeV. Photons of lower energy would be classed as X rays, but what about energies above 10 MeV? The answer is that they are simply higher energy gammas.
Like most such dictionaries, this one leaves out some points. For example, although there is quite a lot about quantum processes in the Cosmos, there is no entry for binding energy and also none for virtual particles, which are the basic constituents of quantum fields and therefore of much of virtual particles, which in turn are the basic constituents of quantum fields and so of much of the Cosmos.
Apart from a few such omissions, which are perhaps difficult to avoid in a selective work, the book as a whole is amazingly comprehensive and should be a valuable purchase for anyone who wants an up-to-date summary of our present picture of the Universe.
Robert Gilmore is author of Scrooge's Cryptic Carol: Three Visions of Energy, Time and Quantum Reality (Sigma)