Introduction

Theoretical physics is the branch of physics that deals with developing and evolving theory to explain the fundamental nature of the universe. It is possibly the most important branch of physics in that without it physics would stagnate and no new discoveries or ideas would develop.

Theoretical physics is the earliest form of science and our earliest written records show that it began over 2,500 years ago in ancient Greece. The scholars of ancient Greece were the first we know of to attempt a thoroughgoing investigation of the universe. They did this through a systematic gathering of knowledge through the activity of human reason alone which we call today philosophy. And for many centuries afterward, the term philosophy was used as the equivalent of the word science which is a recent invention.

Greek natural philosophy was the first attempt to explain the universe without resorting to the supernatural. The Greek word for "natural" isphysikos, which is where we get our modern word for the science of physics.

One of the first phenomena that the Greeks contemplated was motion. The Greek ideas on motion were put into sophisticated form by the philosopher Aristotle (384-322 B.C.). In Aristotle's theory, objects or elements had a natural place. He basically theorized that objects on earth made of earth, water, fire or air tended to return to their natural place