Introduction

• The presumed set of truly elementary particles
• The relationship between the fundamental particles and the fundamental interactions
• Why gravity doesn’t quite fit the standard model
• Where (some) elementary particles get their mass

We extend our discussion of the fundamental interactions into a more detailed look at the relatively small number of fundamental particles we now know exist. We’ll see which particles participate in which of the fundamental interactions. We’ll find an interesting correspondence between electrons and quarks, and discover that they each come in three “generations.”

We’ll dip our toes into something called quantum field theory, the general framework that has been extremely successful at making all sorts of predictions about fundamental particles. We’ll see how this explains the existence and properties of our old friends the proton and neutron, including the spontaneous conversion of one to the other.

The specific applications of quantum field theory to electromagnetism and to the strong and weak nuclear forces, along with the families of fundamental particles, all fit nicely into what we call the “standard model” of particle physics. The one fundamental interaction that doesn’t fit so well is gravity. Before the end we’ll look at why that is the case.