James Hartle
University of California

Living in a superposition

This talk will describe a model quantum universe consisting of a very large box containing a screen with two slits and an observer (us) that can pass through the slits. We apply the modern quantum mechanics of closed systems to calculate the probabilities for alternative histories of how we move through the universe and what we see. After passing through the screen with the slits, the quantum state of the universe is a superposition of classically distinguishable histories. We are then living in a superposition. Some frequently asked questions about such situations are answered using this model. In particular we will discuss whether or not if we are living in a superposition we would in some way feel it.