ABSTRACT
This chapter outlines assumptions about what constitutes the matter of the world. It looks at the general properties of all the known fields, and focuses on some detailed properties of the electromagnetic field, which is by far the most important from our point of view. The chapter looks at the components of the world and some of the tools we use to understand how the components interact. Then it looks at techniques for calculating the properties of large numbers of particles. Electrons are currently considered fundamental particles at the deepest level at which scientists can study them. The total number of protons and neutrons in the universe is not thought to have changed very much since shortly after the start of the universe. The atoms are held together by electrical interactions between the outer electrons on each atom, known as chemical bonds.
