Book excerpt: How science fiction has been a tool for understanding and living through rapid technological change. The world today seems to be slipping into a science fiction future. We have phones that speak to us, cars that drive themselves, and connected devices that communicate with each other in languages we don't understand. Depending the news of the day, we inhabit either a technological utopia or Brave New World nightmare. This volume in the MIT Press Essential Knowledge surveys the uses of science fiction. It focuses on what is at the core of all definitions of science fiction: a vision of the world made otherwise and what possibilities might flow from such otherness.