Within our lifetime, scientific advances have fundamentally changed our world. This book describes scientific advances in five areas that changed the course of humanity, and set the stage for our generation and those to follow to play out our lives. These advances underpinned technological revolutions, and transformed some of our most basic notions of how the world works. Aircraft and the air transport revolution Nuclear energy: Mankind’s saviour or curse? Relativity and the nature of time and space The electricity, electronics and digital revolution Pushing structural limits of what can be built. The author sets these developments in perspective of his own experiences growing up amidst an electronics revolution, onset of the jet age, and the Cold War within the surroundings of New York City undergoing major social, racial and physical transitions. To make sense of these developments, the author draws upon his subsequent training and experience as a physical chemist, scientific writer, and specialist in energy technology. The content of this book formed the basis for the course "Science and the Big Issues of Our Time", taught by the author at the University of the Third Age (U3A) in Brisbane, Australia over a two-year period.