My general aim in writing this book is to help you, and incidentally myself, to understand the properties of matter. In general, the properties that we seek to understand are the large scale (or macroscopic) properties of matter. These properties are familiar to us: for example density, colour or viscosity. In our explanations of why these properties have the values that they do, reference will often be made to the microscopic components of matter. So from the outset we need to be clear about what the components of matter are, and what general principles we may use to analyse their behaviour.

In this context, the principles are analogous to ‘tools’ for understanding ‘components’, which we may think of as the ‘nuts and bolts’ of matter. Historically, the principles evolved to allow analysis of particular problems, in rather the same way that mechanical tools have evolved. For example, screwdrivers have evolved to be good at turning screws. However, for the uninitiated, it is often difficult to distinguish between the ‘tools’ used to analyse a problem and the ‘nuts and bolts’ of the problem itself: it all looks like ‘just so much metal’.

In the context of this book we consider the following ‘components’ of the world: electrons, neutrons, and protons; and the electromagnetic field. The ‘tools’ which we shall use are: classical mechanics and quantum mechanics; thermodynamics and statistical mechanics.

In what follows I assume that readers will have had some introduction to the topics outlined above. However, my experience tells me that, for many students, their understanding of some of these subjects remains scanty. For this reason, the presentation here assumes as little as possible in the way of background knowledge and confines itself to a few words of explanation together with the key results that students will need in the later chapters.

This chapter is divided into four sections:

§2.2 Matter: Here we outline our assumptions about what constitutes the matter of the world.

§2.3 The electromagnetic field: Here we look at the general properties of all the known fields, and focus on some detailed properties of the electromagnetic field, which is by far the most important from our point of view.

§2.4 Classical and quantum mechanics: Having looked at the components of the world, we will look at some of the tools we use to understand how the components interact.

§2.5 Thermodynamics and statistical mechanics: Finally we look at techniques for calculating the properties of large numbers of particles.