Introduction

In our discussion of quantum field theory, we have so far focused on a nonrelativistic treatment of quantum mechanics. Quantum fields, however, are inherently relativistic objects, and we need a consistent framework to describe spacetime. This is where special relativity comes in.

This will assume that the reader at least has a basic understanding of special relativity. We will go quite advanced in this section, including topics such as the Lorentz group, Weyl/Dirac spinors, and curved spacetime (general relativity). We will also briefly discuss an attempt to make quantum mechanics relativistic by using the Klein-Gordon equation, which is ultimately unsuccessful. Then, we will realize that a relativistic theory of quantum mechanics requires us to use field theories, which leads us to the next chapter.