Understanding Relativity: An Advanced Guide for the Perplexed (English Edition)

This book is about the meaning of relativity. It does not explain counterintuitive phenomena or solve paradoxes in terms of the theory of relativity. These explanations and solutions can be found in many books on relativity. Rather, the purpose of the book is to understand the fundamental postulates of the theory and search for its deeper meaning. Why is there an invariant speed? Why is the invariant speed not infinite but finite? And why is there gravity? These deep questions have not been answered or even touched upon. Only after answering them, can one really understand relativity and the universe it describes.

This book first introduces the existing attempts to answer these questions and then proposes an intriguing new answer, according to which a certain kind of discreteness of space-time may not only explain the invariance of the speed of light, but also explain the origin of gravity. Moreover, the book gives a new derivation of the energy-momentum relation based on fundamental principles, and further shows that, contrary to most people’s expectations, Einstein’s famous equation E=mc2 is actually a convenient definition.

This book is supplementary to standard textbooks and accessible to undergraduate students in physics. It will be of value to all those with an interest in the meaning of relativity.