Quantum Mechanics 2

Noel Swanson (University of Delaware)
The thermal time hypothesis (TTH) is a proposed solution to the problem of time: every statistical state determines a thermal dynamics according to which it is in equilibrium, and this dynamics is identified as the flow of physical time in generally covariant quantum theories. This paper raises a series of objections to the TTH as developed by Connes and Rovelli (1994). Two technical challenges concern the implementation of the TTH in the classical limit and the relationship between thermal time and proper time. Two more conceptual problems focus on interpreting the flow of time in non-equilibrium states and the lack of gauge invariance.

Eugene Chua (University of California, San Diego)
The gauge/gravity duality and its relation to the possible emergence (in some sense) of gravity from quantum physics has been much discussed. Recently, however, Sebastian De Haro (2017) has argued that the very notion of a duality precludes emergence, given what he calls the internal view of dualities, on which the dual theories are physically equivalent. However, I argue that De Haro's argument for the internal view is not convincing, and we do not have good reasons to adopt it. In turn, I propose we adopt the external view, on which dual theories are not physically equivalent, instead.

Pablo Ruiz de Olano (Max Planck Institute for the History of Science)
In this paper, I study the manner in which symmetries and conservation laws relate to each other in quantum and in classical mechanics. The paper contains two main claims. First, I argue that the nature of the connection between symmetries and conservation laws is different in the Hilbert space formulation of quantum mechanics and in the Hamiltonian formulation of classical mechanics. This is because in the latter case, unlike in the former one, there are symmetries of the equations of motion that do not give rise to a conservation law. Secondly, I claim that future research ought to focus on comparing the manner in which symmetries and conservation laws relate to each other in different formulations of the same physical theories.

Eddy Keming Chen (Rutgers University)
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 paper, 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. This new package of ideas has several interesting implications, including on the theoretical unity of statistical mechanics and quantum mechanics, and and the alleged conflict between Humean supervenience and quantum entanglement.