This second edition of “Let there be Light: the Story of Light from Atoms to Galaxies” is, like the first edition, a delightful book. Light, or more generally electromagnetic radiation, is the vehicle that the authors use to traverse the broad subject of physics, and they do so in a humorous, gentle, yet serious manner. Although many of the topics have been revised – and the last chapter updated to cater for the emergence of the Higgs boson – the book has lost none of the appeal of the first edition. While the presentation is of a level suitable for third level students, there is much in the book that can whet the appetite of the bright senior school students engaged in their first serious study of the subject. Additionally, teachers of physics at second and third level will find insights and anecdotes aplenty to flavour the teaching process.
The book has a pleasant and light narrative flow, with excellent illustrations, photos, and occasional well-chosen “historical interludes”. Topics are, nevertheless, treated with a good degree of rigour. In the second edition, most of the mathematical derivations, which appeared as appendices to the chapters of the first edition, have been replaced with verbal descriptions, and key mathematical statements are presented on “blackboards”, all to make the book more accessible to the general reader. At risk of being considered decidedly old-fashioned, I admit to regretting the elimination of the mathematical appendices. Physics is well served by mathematics, and the serious student learns to appreciate the precision and clarity that mathematical analysis can bring to a topic.
The book attempts, with a good deal of success, to show an underlying connectivity between the seemingly disparate topics that confront the student embarking on a study of physics. It also places the topics in a historical context, emphasising the many human endeavours that have contributed to our remarkable modern understanding of the physical world. Affording due respect to the human endeavours that have led to great discoveries, without unnecessarily encumbering the student, is a delicate matter.
For example, we cannot expect a young student to follow Planck’s torturous journey to his discovery of the quantisation of the energy of the atomic linear harmonic oscillator (as described so well in Malcolm Longair’s recent book “Quantum Concepts in Physics”). With the benefit of hindsight, one can simplify the story to one much more amenable to the student, but one is in danger that a phrase such as “Planck’s discovery of light quanta” (as quoted in the Preface) will find its way into the narrative. The story is correctly told in pages 18 and 19, and due acknowledgement is made to Einstein, who in 1905 extended Planck’s idea of quantisation to light itself.
For the true physicist, there is a wondrous beauty in physics. This book is much in sympathy with this viewpoint, and it ends by quoting Abdus Salaam on the faith of all physicists: “the deeper we seek the more is our wonder excited”. This may be the book that affords the struggling student a glimpse of the beauty that makes the serious study of physics so worthwhile.