It is extremely difficult to visualize a curved four-dimensional space-time manifold. The penrose diagram makes it easier by bringing these infinities into a finite distance, thus allowing you to plot the infinite space-time in your finite two-dimensional notebook paper. These diagrams were invented by Roger Penrose, who used to call them conformal diagrams. Penrose diagrams focus on two key features: the causality and the global structure of space-time and squeeze an infinite spacetime into causally meaningful finite coordinates – we’ll unpack all these words in today’s video!