By Iain Nicolson, Canopus. Hardback ISBN 0954984633, £19.95.
If you are a particle physicist interested in cosmology, this book is for you. It makes a broad, clear and precise overview of our current understanding of dark matter and dark energy – the invisible actors governing the fate of the universe.
It is a challenge to try to make these apparently obscure concepts familiar to any motivated reader without a scientific background. But the author, Iain Nicolson, has been entirely successful in his enterprise. With a pleasant balance between text and colourful illustrations, he guides the reader through a fascinating, invisible and mysterious world that manifests its presence by shaping galaxies and the universe itself.
The book starts with an introduction to key concepts in astrophysics and the development of classical cosmology. It then describes the observational evidence for dark matter in galaxies and clusters of galaxies, showing that massive extremely dim celestial bodies cannot account for the missing mass. Particle physics is not neglected, with a description of our understanding of ordinary “baryonic” matter and the quest for detecting exotic weakly interacting massive particles (WIMPs). An entire chapter is also devoted to the idea that modified Newtonian dynamics (MOND) could be an alternative to the existence of dark matter. The second half of the book is devoted to cosmological observations and arguments that suggest the existence of dark energy – an even more mysterious ingredient of the universe. The pieces assemble through these chapters to reveal a universe that is flattened out by inflation and that is essentially made of cold dark matter, with dark energy acting as a cosmological constant.
This new cosmology is generally accepted as the standard model and gives the full measure of the dark side of the universe. The visible matter studied by astronomers so far appears to be just the tip of the iceberg (less than 1%) and even baryonic matter studied so far by physicists is only about 5% of the mass–energy content of the universe. The remaining 95% is unknown territory, which the book invites us to explore using all techniques available. This will be the major challenge for physics in the 21st century.
