Title: Observers, alpha parameters, and the Hartle-Hawking state
Abstract: In this talk I will clear up some misunderstandings about the gravitational path integral and quantum gravity in a closed universe. I will explain that there are really three inequivalent versions of the path integral, each of which appears in various applications. For example I will explain why the closed string Hilbert space is not one-dimensional, and also why Coleman's alpha-parameters do not resolve the black hole information problem. I will explain a connection between recent proposals for using an observer to resolve the one-dimensional Hilbert space problem and the coarse-grained spectral form factor in AdS/CFT, and I will also explain the (nontrivial) relationship between the Hartle-Hawking state and the unique state of holographic cosmology.
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