Relativity Lite

AUTHOR’S NOTE This book grew out of my 80-student general astronomy course, which I’ve taught for 20 years and whose variety of primary textbooks always glossed over special relativity and general relativity while trying to explain the cosmology that is based on those subjects. Most of my students have been juniors and seniors who are desperate to get their science require- ment fulfilled, hoping for as little math as possible. Over the years, I learned to translate the mathematical equations conventional relativity texts rely on into pictures that are readily understood and contain within them the mathematical essentials. This book provides the comprehensive coverage needed to understand, in sufficient depth, these three linked areas of our reality. It may be useful in other courses, such as Physics for Poets, Learning Science Through Science Fiction, and Natural Science Inquiry. Though one seldom gets physics majors in such courses, a number of those who have taken them have remarked that they never really understood relativity before learning anew in this pictorial form. So this material likely has a place in a modern physics course as well. Readers seeking this knowledge on their own may also find it helpful. I am grateful for the Portland State University (PSU) Library’s support of this project through its Open Educational Resources Grant Program (OERGP) and particularly ap- preciate the guidance Karen Bjork, head of Digital Initiatives, has given me. I would also like to thank Drs. Brad Armen and Priya Jamkhedkar for their willingness to review the manuscript for clarity and missteps. I would like to dedicate this book to my father, G. Douglas Straton, whose joy in science coupled to deep scholarship as a philosopher of religion set me on a lifetime path of inquiry and teaching. Jack C. Straton, December 2019