A documentary for those of you interested in the wonders of the universe and beyond, as it explores the 'multiverse', a theoretical approach to some of the fundamental questions of existence, which posits that an infinite number of universes exists. Each of these separate universes is defined by the way they differ from the others, in a concept seized upon by science-fiction writers to depict worlds where dinosaurs still live and the Germans won the Second World War, among other fantastical variations. The programme reveals that, until relatively recently, the 'multiverse' theory was dismissed as a fantasy, but now this unusual idea has found its way to the forefront of scientific thinking, and for a growing number of scientists, has become fundamental to understanding the nature of reality.