What would it mean to say that turning back time is possible? In media technologies, reversal becomes a real possibility due to how time is rendered spatial. One only needs to think of playing backwards a piece of recorded music or a film to understand reversibility at the basis of storage media. However, reversibility takes on a new form with the historical advent of cybernetics and computation: real time appears manipulable with virtual models and transmission technologies making interventions into the real world. This course tracks the notion of temporal reversibility by making a quarter-length argument vis-a-vis media philosophy. It has one overarching throughline: that media make the world and our temporal experience of it, rather than simply mirroring and interpreting said world. Starting with the alphabet and writing and ending with computer modeling, students will also tacitly learn about media history through the primary lens of a philosophy of media techniques. These, as we will soon see, are techniques (and technologies) of worldmaking (cosmopoiesis).