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arXiv · 2101.12221

Baby Universes and Worldline Field Theories

Eduardo Casali·Donald Marolf·Henry Maxfield·Mukund Rangamani
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Abstract

The quantum gravity path integral involves a sum over topologies that invites comparisons to worldsheet string theory and to Feynman diagrams of quantum field theory. However, the latter are naturally associated with the non-abelian algebra of quantum fields, while the former has been argued to define an abelian algebra of superselected observables associated with partition-function-like quantities at an asymptotic boundary. We resolve this apparent tension by pointing out a variety of discrete choices that must be made in constructing a Hilbert space from such path integrals, and arguing that the natural choices for quantum gravity differ from those used to construct QFTs. We focus on one-dimensional models of quantum gravity in order to make direct comparisons with worldline QFT.

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Eduardo Casali, Donald Marolf, Henry Maxfield, Mukund Rangamani. 2022-01-28. Baby Universes and Worldline Field Theories. https://doi.org/10.1088/1361-6382%2Fac37cd

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