Special relativity is a subject in which intuition is a dangerous tool. Statements such as ‘moving clocks go slow’ or ‘moving rulers are length contracted’ are common currency but, in my view, they can hinder rather than help an understanding of special relativity. In such non-intuitive areas, it is important to have at hand a robust formalism which can be relied upon to give correct answers. After a number of years of teaching the subject, I have concluded that the best approach is to introduce the Lorentz transformations and four-vectors as quickly as possible. These provide a simple set of rules which enable most reasonably straightforward problems in special relativity to be tackled with confidence. This approach involves constructing a four-vector algebra and calculus with rules essentially identical to those of three-vectors.

On researching the history of special relativity, it became apparent that many of my favourite tricks were well known to the pioneers, and so this case study begins with a modest historical introduction. I would emphasise that this is not intended as a course in special relativity, in which every ‘i’ is dotted and every ‘t’ crossed. Rather the emphasis is upon the creation of a mathematical structure which enables relativistic calculations to be carried out as simply as possible.

Throughout this book, I have suppressed any detailed discussion of what I call the genius of experiment, the exception being in Chapter 18, in which I give full rein to my enthusiasm for the experimental and observation foundations of cosmology.