Understanding Relativity: A Simplified Approach to Einstein's Theories

Understanding Relativity: A Simplified Approach to Einstein's Theories

Understanding Relativity: A Simplified Approach to Einstein's Theories

Understanding Relativity: A Simplified Approach to Einstein's Theories


Nonspecialists with no prior knowledge of physics and only reasonable proficiency with algebra can now understand Einstein's special theory of relativity. Effectively diagrammed and with an emphasis on logical structure, Leo Sartori's rigorous but simple presentation will guide interested readers through concepts of relative time and relative space.

Sartori covers general relativity and cosmology, but focuses on Einstein's theory. He tracks its history and implications. He explores illuminating paradoxes, including the famous twin paradox, the "pole-in-the-barn" paradox, and the Loedel diagram, which is an accessible, graphic approach to relativity. Students of the history and philosophy of science will welcome this concise introduction to the central concept of modern physics.


Albert Einstein’s special theory of relativity, one of the supreme achievements of the human intellect, is more accessible to a nonspecialist audience than is commonly believed. Over the past twenty years I have taught relativity with some success to a diverse group of students at the University of Nebraska, including some with little or no previous physics and with limited mathematical preparation. This book is intended to serve as a text for such a course, as well as to guide the reader who wishes to study the subject independently.

Relativity is a challenge, but the challenge is in the ideas, not in the mathematics. The reader should not be put off by the fairly large number of equations; nearly all of them involve nothing more than simple algebra. Some of the more complex mathematical sections can be omitted without disrupting the development.

Although this book is on an elementary level, it is by no means a watered-down version of relativity. The logical arguments are presented in a rigorous manner, and the major conceptual difficulties are addressed. For example, I discuss in detail the connection between the possible reversal in the time order of events, predicted by relativity, and the logical requirement of causality (the cause must precede the effect). It is my hope that even sophisticated readers will find the presentation stimulating.

The emphasis throughout is on the concepts and the logical structure of the theory. To that end, introduction of the Lorentz transformation is delayed until chapter 4. In chapter 3, the relativity of simultaneity and the time dilation and length contraction effects are deduced directly from Einstein’s two postulates and are analyzed exhaustively. These profound conclusions concerning the nature of space and time constitute the heart . . .

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