  This essay considers a model quantum universe consisting of a very large box
containing a screen with two slits and an observer (us) that can pass though
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. The model's
relationship to more realistic quantum cosmologies is briefly discussed.
