From the Preface: “This book is intended for the intelligent person who wants to know what modern cosmology is about. It assumes no previous knowledge of the subject and no mathematics, though there are a few footnotes for readers with a mathematical turn of mind. The physics and astronomy required are supplied as the need arises…”
William B. Bonnor (1920–2015) was a British mathematician and physicist known for his contributions to general relativity and cosmology, including the "Bonnor beam" in 1969. He authored the popular science book The Mystery of the Expanding Universe and taught mathematics at Queen Elizabeth College, University of London.