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SUMMARY:Daniel Harlow (MIT)
DTSTART:20260317T183000Z
DTEND:20260317T193000Z
DTSTAMP:20260423T005707Z
UID:nhetc/142
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/nhetc/142/">
 Observers\, alpha parameters\, and the Hartle-Hawking state</a>\nby Daniel
  Harlow (MIT) as part of NHETC Seminar\n\n\nAbstract\nIn 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 reall
 y three inequivalent versions of the path integral\, each of which appears
  in various applications.  For example I will explain why the closed strin
 g Hilbert space is not one-dimensional\, and also why Coleman's \\alpha-pa
 rameters do not resolve the black hole information problem.  I will explai
 n a connection between recent proposals for using an observer to resolve t
 he one-dimensional Hilbert space problem and the coarse-grained spectral f
 orm factor in AdS/CFT\, and I will also explain the (nontrivial) relations
 hip between the Hartle-Hawking state and the unique state of holographic c
 osmology.\n
LOCATION:https://researchseminars.org/talk/nhetc/142/
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