# Time’s arrow in a quantum universe

**Eddy Chen**

In a quantum universe with a strong arrow of time, we postulate a low-entropy boundary condition (the Past Hypothesis) to account for the temporal asymmetry. In this talk, I show that the Past Hypothesis also contains enough information to simplify the quantum ontology and define a unique initial condition in such a world. To that end, I propose a new class of quantum theories. These new theories have interesting implications about the status of statistical-mechanical probabilities, the nature of the quantum state, and the alleged conflict between Humean supervenience and quantum entanglement.