12. Observers in quantum cosmology (Daniel Harlow and Luca Iliesiu) скачать в хорошем качестве

12. Observers in quantum cosmology (Daniel Harlow and Luca Iliesiu)

Date: February 5th, 2026 Speaker 1: Daniel Harlow Title: Observers, alpha parameters, and the hartle hawking state Abstract: In this talk I will review some aspects of the path integral approach to quantum cosmology and explain how it relates to holography and the issue of a unique state. In particular I will discuss the role of observers, and point out a connection to rhe structure of the landscape. Speaker 2: Luca Iliesiu Title: The gravitational path integral from an observer's point of view Abstract: Is there a quantum mechanical description for cosmological spacetimes? A traditional approach to this question is to use the gravitational path integral (GPI) to compute transition amplitudes between different closed universe states. To ensure that amplitudes are correctly normalized, one must also use the GPI to compute the norms of the involved states. I will describe how correctly computing the norms dramatically alters the transition probabilities between all closed universe states of interest in cosmology. We find that probabilities are either nearly 1, or exactly 1 making such states practically indistinguishable. To resolve this problem, I will then describe a framework in which the gravitational path integral can be used to describe physics in the closed universe relative to an observer. When using this framework, we instead find sensible results in which the QFT in curved spacetime approximation is valid and in which different closed universe states now become distinguishable.