How do things work? What makes up matter? How large is the universe? The answer to these questions lies in understanding physical phenomena: mechanics, electricity, magnetism, optics and many other phenomena can be explained through theories in physics. Indeed, progress in physics has been crucial for mankind’s technological progress. Theories and Theorems is an introductory handbook that gives readers a simple explanation of the laws of physics and presents these concepts in a way that stimulates people to think about the how-and-why of this physical world, in which we live.