Understanding relativity : a conceptual journey into spacetime black holes and gravitational waves This book bridges the huge gap between popular science and mathematical treatments of Einsteins theories. It explains special and general relativity gravity black holes and gravitational waves also presenting current ideas about dark matter and dark energy. The explanations are entirely non mathematical using many color pictures and clear concepts. In this way the reader is led to a much deeper understanding than any popular science book can provide. The author has written this book for everyone who wants to go beyond superficial descriptions of relativitys remarkable phenomena but is not equipped to read the professional literature and complicated math behind the theory. By providing a complete description in terms of concepts and pictures the book answers many questions about why the theory works as it does. For example it explains why and how momentum and pressure are related to gravity; why and how mass causes spacetime to curve and how curvature tells objects how to move; it also reveals the origin of the ring seen around the first ever image of a black hole. Not least the reader will learn in detail how gravitational waves are produced and measured. Since their conception the theories of relativity have appealed to the publics imagination. Thanks to this book readers now have the opportunity to convert their fascination with the topic to a deep understanding.