Special Relativity

Abstract

References 43 Index 45 ii Preface For me, the wonder of special relativity lies in its successful prediction of interesting and very nonintuitive phenomena from simple arguments with simple premises. These notes have three (perhaps ambitious) aims: (a) to introduce undergraduates to special relativity from its founding principle to its varied consequences, (b) to serve as a reference for those of us who need to use special relativity regularly but have no long-term memory, and (c) to provide an illustration of the methods of theoretical physics for which the elegance and simplicity of special relativity are ideally suited. History is a part of all science—I will mention some of the relevant events in the development of special relativity—but there is no attempt to present the material in a historical way. A common confusion for students of special relativity is between that which is real and that which is apparent. For instance, length contraction is often mistakenly thought to be some optical illusion. But moving things do not " appear " shortened, they actually are shortened. How they appear depends on the particulars of the observation , including distance to the observer, viewing angles, times, etc. The observer finds that they are shortened only after correcting for these non-fundamental details of the observational procedure. I attempt to emphasize this distinction: All apparent effects, including the Doppler Shift, stellar aberration, and superluminal motion, are relegated to Chapter 7. I think these are very important aspects of special relativity, but from a pedagogical standpoint it is preferable to separate them from the ba-sics, which are not dependent on the properties of the observer. I love the description of special relativity in terms of frame-independent, geometric objects, such as scalars and 4-vectors. These are introduced in Chapter 6 and used thereafter. But even before this, the geometric properties of spacetime are emphasized. Most problems can be solved with a minimum of algebra; this is one of the many beautiful aspects of the subject. These notes, first written while teaching sections of first-year physics at Caltech, truly represent a work in progress. I strongly encourage all readers to give me comments on any aspect of the text * ; all input is greatly appreciated. Thank you very much.