Teaching Special Relativity Without Calculus

I 2007 many AAPT members received a booklet that is the first chapter of a physics textbook¹ available on a CD. This book espouses the new educational philosophy of teaching special relativity as the first item in the topic of mechanics. Traditionally, special relativity is part of one or more modern physics chapters at the end of the text,² and very often this material is never utilized due to time constraints. From a logical standpoint, special relativity is important in satellite communications and in cosmology, as well as in modern physics applications such as atomic theory and high-energy physics. The purpose of this paper is to show that the new philosophy can be carried out in a noncalculus physics course, by demonstrating that all of the principal results of special relativity theory can be obtained by simple algebra. To accomplish this, we shall propose alternate derivations for two results that are usually obtained with calculus. Textbooks² typically obtain the equations for time dilation and for length contraction from simple considerations based on Einstein's second postulate.³ We shall start from this point.