Vorträge in der Woche 18.03.2019 bis 24.03.2019

Donnerstag, 21.03.2019: Time's Arrow in a Quantum Universe: On the Simplicity and Uniqueness of the Initial Quantum State

Eddy Keming Chen (Rutgers)

In a quantum universe with a strong arrow of time (large entropy gradient), it is standard to postulate a low-entropy boundary condition (the Past Hypothesis) to account for the temporal asymmetry. In this talk, I show that we can use the Past Hypothesis to determine, in a natural way, the initial quantum state of the universe, which turns out to be simple and unique. This is achieved by what I call the Initial Projection Hypothesis: the initial quantum state of the universe is the normalized projection onto the Past Hypothesis subspace in the Hilbert space of the universe. The observation enables us to define a new class of quantum theories and has interesting implications for the status of statistical mechanical probabilities and the nature of the universal quantum state. Related papers: https://arxiv.org/abs/1901.08053 https://arxiv.org/abs/1712.01666 https://arxiv.org/abs/1902.04564