Introduction

Abstract

There was a time when ancient Greek cosmologists disagreed profoundly about the fundamental nature of the physical world. Some argued that everything is ultimately made of fire, some that everything is air, others that everything is water, others that everything is made of indivisible ‘atoms’, still others that everything is ‘the boundless,’ and so on.¹ Fortunately, that time is past. Although physics is still incomplete, we now know that the visible matter of our universe is composed of subatomic particles such as quarks and electrons interacting via other force-carrying particles.²