There are no events at the Simons Center today. Here are the events for this week
Monday, December 8th, 2025
Workshop: Grigorios Fournodavlos
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: The initial boundary value problem for the Einstein vacuum equations with umbilic boundary
Speaker: Grigorios Fournodavlos
Abstract: In this talk, we will discuss the initial boundary value problem in general relativity from a mathematical point of view. We will first make the analogy to the classical Cauchy problem for the Einstein equations, first resolved by Yvonne Choquet-Bruhat in 1952, and highlight some desired properties that a potential treatment of timelike boundaries should have. Then, we will go over the various technical difficulties that arise in such an endeavor. The main result that we will present in the end concerns the local well-posedness of the problem for homogeneous Neumann conditions, in geometric terms, when the boundary is umbilic.
Title: The initial boundary value problem for the Einstein vacuum equations with umbilic boundary
Speaker: Grigorios Fournodavlos
Abstract: In this talk, we will discuss the initial boundary value problem in general relativity from a mathematical point of view. We will first make the analogy to the classical Cauchy problem for the Einstein equations, first resolved by Yvonne Choquet-Bruhat in 1952, and highlight some desired properties that a potential treatment of timelike boundaries should have. Then, we will go over the various technical difficulties that arise in such an endeavor. The main result that we will present in the end concerns the local well-posedness of the problem for homogeneous Neumann conditions, in geometric terms, when the boundary is umbilic.
Workshop: Batoul Banihashemi
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title: Thermodynamics of gravity at finite cutoff
Speaker: Batoul Banihashemi
Abstract: Defining thermodynamic ensembles for gravitational systems is tied to specifying boundary conditions. In this talk I'll first briefly review how introducing a Dirichlet timelike boundary clarifies thermodynamics of de Sitter space. Then I'll discuss geometries subjected to conformal boundary conditions, where the conformal class of the boundary metric and the trace of the extrinsic curvature K are held fixed. In the high temperature limit the series of subextensive terms in the free energy are compared to predictions from thermal effective field theory, and we observe agreement in all considered cases. Ensembles with negative K include solutions with cosmic-type horizons, where the system boundary is smaller than the horizon. In some regions of parameter space, these solutions are the dominant phase and are necessary for consistency with thermal effective field theory.
Title: Thermodynamics of gravity at finite cutoff
Speaker: Batoul Banihashemi
Abstract: Defining thermodynamic ensembles for gravitational systems is tied to specifying boundary conditions. In this talk I'll first briefly review how introducing a Dirichlet timelike boundary clarifies thermodynamics of de Sitter space. Then I'll discuss geometries subjected to conformal boundary conditions, where the conformal class of the boundary metric and the trace of the extrinsic curvature K are held fixed. In the high temperature limit the series of subextensive terms in the free energy are compared to predictions from thermal effective field theory, and we observe agreement in all considered cases. Ensembles with negative K include solutions with cosmic-type horizons, where the system boundary is smaller than the horizon. In some regions of parameter space, these solutions are the dominant phase and are necessary for consistency with thermal effective field theory.
Workshop: Don Marolf (Zoom)
Time: 2:30 PM - 3:30 PM
Location: SCGP 102/ZOOM
Title: Timelike Dirichlet Boundaries and the End of Time
Speaker: Don Marolf
Abstract: For Einstein-Hilbert gravity with a time-independent finite-distance timelike boundary, there is a sector of the theory where the dynamics leads to a big-bang- or big-crunch-like singularity in finite proper time. We establish this in detail in 2+1 dimensions with negative cosmological constant and discuss transitions between this sector and seemingly more-stable sectors of the theory.
Title: Timelike Dirichlet Boundaries and the End of Time
Speaker: Don Marolf
Abstract: For Einstein-Hilbert gravity with a time-independent finite-distance timelike boundary, there is a sector of the theory where the dynamics leads to a big-bang- or big-crunch-like singularity in finite proper time. We establish this in detail in 2+1 dimensions with negative cosmological constant and discuss transitions between this sector and seemingly more-stable sectors of the theory.
Workshop: Gonzalo Torroba (Discussion)
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: Quantum aspects of time-like boundaries
Speaker: Gonzalo Torroba (Discussion)
Abstract: Timelike boundaries in gravitational systems provide a powerful framework for understanding quasilocal holography, cosmological horizons, and the microscopic structure of spacetime in the absence of asymptotic regions. This discussion session will focus on quantum aspects of timelike boundaries, including possible UV completions, lessons from holography, and effects from quantum fields. Participants are invited to share perspectives, open problems, and recent progress in this area.
Title: Quantum aspects of time-like boundaries
Speaker: Gonzalo Torroba (Discussion)
Abstract: Timelike boundaries in gravitational systems provide a powerful framework for understanding quasilocal holography, cosmological horizons, and the microscopic structure of spacetime in the absence of asymptotic regions. This discussion session will focus on quantum aspects of timelike boundaries, including possible UV completions, lessons from holography, and effects from quantum fields. Participants are invited to share perspectives, open problems, and recent progress in this area.
Tuesday, December 9th, 2025
Workshop: Xiaoyi Liu
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: Euclidean well-posedness and Lorentzian ill-posedness of generalized conformal boundary conditions
Speaker: Xiaoyi Liu
Abstract: We study four-dimensional Einstein gravity with a finite boundary. We introduce a one-parameter family generalization of Anderson’s conformal boundary condition and show that these boundary conditions lead to a well-posed elliptic system in Euclidean signature. We further discuss the associated thermodynamic properties. In Lorentzian signature, we analyze the corresponding initial-boundary value problem (IBVP) and demonstrate that these boundary conditions render the system ill-posed at the linearized level.
Title: Euclidean well-posedness and Lorentzian ill-posedness of generalized conformal boundary conditions
Speaker: Xiaoyi Liu
Abstract: We study four-dimensional Einstein gravity with a finite boundary. We introduce a one-parameter family generalization of Anderson’s conformal boundary condition and show that these boundary conditions lead to a well-posed elliptic system in Euclidean signature. We further discuss the associated thermodynamic properties. In Lorentzian signature, we analyze the corresponding initial-boundary value problem (IBVP) and demonstrate that these boundary conditions render the system ill-posed at the linearized level.
Workshop: Gauri Batra
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title: A theory of two-sided de Sitter space with matter and the cosmological future wedge
Speaker: Gauri Batra
Abstract: We show how to capture the states in the spectrum of two-sided de Sitter space with timelike boundaries, taking into account the causal connection between the two boundaries in states with matter. To do so, we review the construction of the theory describing one static patch with a timelike boundary via a deformation of AdS/CFT. We outline how this leads to a microstate count of the de Sitter horizon. We then study the two-sided theory by constructing the thermofield double for this system. We show how to consistently combine the one-sided theories to produce a theory of the two-sided system, where the two boundaries are in causal contact. This theory reproduces some expected properties of the two-sided system. We end with some exploration of bulk reconstruction in this framework, enabling us to study the cosmological future wedge
Title: A theory of two-sided de Sitter space with matter and the cosmological future wedge
Speaker: Gauri Batra
Abstract: We show how to capture the states in the spectrum of two-sided de Sitter space with timelike boundaries, taking into account the causal connection between the two boundaries in states with matter. To do so, we review the construction of the theory describing one static patch with a timelike boundary via a deformation of AdS/CFT. We outline how this leads to a microstate count of the de Sitter horizon. We then study the two-sided theory by constructing the thermofield double for this system. We show how to consistently combine the one-sided theories to produce a theory of the two-sided system, where the two boundaries are in causal contact. This theory reproduces some expected properties of the two-sided system. We end with some exploration of bulk reconstruction in this framework, enabling us to study the cosmological future wedge
Workshop: Kuroush Allameh
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Timelike Liouville theory and AdS3 gravity at finite cutoff
Speaker: Kuroush Allameh
Abstract: A brief review of conformal boundary conditions and their thermodynamics will be given. We will then focus on the case of AdS3 subject to these boundary conditions. By analyzing the evidence from bulk calculations, we will propose that the dual theory is described by coupling the holographic CFT2 to timelike Liouville theory and deformed by an exactly marginal operator. We will test this proposal by reproducing the bulk results, and show that one can describe the flat space in conformal boundary conditions by scaling the parameters of the proposed dual such that the resulting flat space dual will also be a CFT2.
Title: Timelike Liouville theory and AdS3 gravity at finite cutoff
Speaker: Kuroush Allameh
Abstract: A brief review of conformal boundary conditions and their thermodynamics will be given. We will then focus on the case of AdS3 subject to these boundary conditions. By analyzing the evidence from bulk calculations, we will propose that the dual theory is described by coupling the holographic CFT2 to timelike Liouville theory and deformed by an exactly marginal operator. We will test this proposal by reproducing the bulk results, and show that one can describe the flat space in conformal boundary conditions by scaling the parameters of the proposed dual such that the resulting flat space dual will also be a CFT2.
Workshop: Chawakorn Maneerat/Andrew Svesko (Discussion)
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: Discussion: The past and future of finite boundaries
Speaker: Chawakorn Maneerat/Andrew Svesko (Discussion)
Abstract: In this discussion we lay out some of the problems finite timelike boundaries have addressed, highlighting novel findings in the context of semi-classical gravity. We also pose open questions that should be addressed in the near and far future.
Title: Discussion: The past and future of finite boundaries
Speaker: Chawakorn Maneerat/Andrew Svesko (Discussion)
Abstract: In this discussion we lay out some of the problems finite timelike boundaries have addressed, highlighting novel findings in the context of semi-classical gravity. We also pose open questions that should be addressed in the near and far future.
Wednesday, December 10th, 2025
Workshop: Zhongshan An (Zoom)
Time: 9:30 AM - 10:30 AM
Location: SCGP 102/ZOOM
Title: Geometric boundary conditions for the IBVP of vacuum Einstein equations
Speaker: Zhongshan An
Abstract: In general relativity, it is of great interest to construct spacetimes satisfying the vacuum Einstein equations. While the Cauchy problem of vacuum Einstein equations has been well studied since the work of Choquet-Bruhat, the initial boundary value problem (IBVP) remains much less understood. To establish a well-posed IBVP, one needs to impose appropriate boundary conditions on the time-like boundary. However, due to the complexity of energy estimate and gauge issue, so far there has not been a canonical choice of boundary conditions. In this talk, I will discuss the local-in-time well-posedness of various choices of geometric boundary conditions for the IBVP based on a series of works joint with Michael Anderson
Title: Geometric boundary conditions for the IBVP of vacuum Einstein equations
Speaker: Zhongshan An
Abstract: In general relativity, it is of great interest to construct spacetimes satisfying the vacuum Einstein equations. While the Cauchy problem of vacuum Einstein equations has been well studied since the work of Choquet-Bruhat, the initial boundary value problem (IBVP) remains much less understood. To establish a well-posed IBVP, one needs to impose appropriate boundary conditions on the time-like boundary. However, due to the complexity of energy estimate and gauge issue, so far there has not been a canonical choice of boundary conditions. In this talk, I will discuss the local-in-time well-posedness of various choices of geometric boundary conditions for the IBVP based on a series of works joint with Michael Anderson
Workshop: Pau Figueras
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title: Timelike boundaries in numerical relativity
Speaker: Pau Figueras
Abstract: In this talk I will discuss the various uses (and misuses) of timelike boundaries in numerical relativity applications, from the construction of stationary black hole solutions to simulations of black hole binary mergers.
Title: Timelike boundaries in numerical relativity
Speaker: Pau Figueras
Abstract: In this talk I will discuss the various uses (and misuses) of timelike boundaries in numerical relativity applications, from the construction of stationary black hole solutions to simulations of black hole binary mergers.
Workshop: Students presentations
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Title: Student presentations
Speaker: Samanta Saha (Case Western U.), Antonia Seifert (Perimeter Institute),Xinkang Wang (Chicago U.), Themistoklis Zikopoulos (Perimeter Institute)
Abstract: See Webpage under Student Presentations for titles and abstracts
Title: Student presentations
Speaker: Samanta Saha (Case Western U.), Antonia Seifert (Perimeter Institute),Xinkang Wang (Chicago U.), Themistoklis Zikopoulos (Perimeter Institute)
Abstract: See Webpage under Student Presentations for titles and abstracts
Workshop: Simone Speziale
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Gravitational charge algebras with open boundary conditions
Speaker: Simone Speziale
Abstract: With open boundary conditions, symmetries may correspond to non-Hamiltonian flows. This hinders the notion of canonical generators, and affects the identification of Noether charges to the symmetries. I will present a prescription that removes the ambiguities, and guarantees that the charges correctly realize the symmetry algebra in the phase space (in particular, without field-dependent 2-cocycles). I will show applications to null boundaries, and discuss some aspects of the time-like case.
Title: Gravitational charge algebras with open boundary conditions
Speaker: Simone Speziale
Abstract: With open boundary conditions, symmetries may correspond to non-Hamiltonian flows. This hinders the notion of canonical generators, and affects the identification of Noether charges to the symmetries. I will present a prescription that removes the ambiguities, and guarantees that the charges correctly realize the symmetry algebra in the phase space (in particular, without field-dependent 2-cocycles). I will show applications to null boundaries, and discuss some aspects of the time-like case.
Workshop: Christopher Kehle
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: Weak turbulence on Schwarzschild-AdS spacetime
Speaker: Christopher Kehle
Abstract: I will present upcoming joint work with G. Moschidis addressing the stability problem for the Schwarzschild-AdS black hole as a solution to the Einstein equations with reflecting boundary conditions at infinity. We prove a "weak turbulent instability’’ for certain quasilinear wave equations on generic Schwarzschild-AdS black holes. The instability is governed by a stably trapped 3-mode interaction transferring energy from low-frequency to high-frequency modes.
Title: Weak turbulence on Schwarzschild-AdS spacetime
Speaker: Christopher Kehle
Abstract: I will present upcoming joint work with G. Moschidis addressing the stability problem for the Schwarzschild-AdS black hole as a solution to the Einstein equations with reflecting boundary conditions at infinity. We prove a "weak turbulent instability’’ for certain quasilinear wave equations on generic Schwarzschild-AdS black holes. The instability is governed by a stably trapped 3-mode interaction transferring energy from low-frequency to high-frequency modes.
Thursday, December 11th, 2025
Workshop: Amr Ahmadain
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: Towards an Algebra of Observables in String Theory
Speaker: Amr Ahmadain
Abstract: It is widely believed that string theory cures the ultraviolet divergences of entanglement entropy that arise in local QFTs, and that the classical entropy of very non–extremal black holes admits a statistical interpretation in a consistent quantum theory of gravity. In ongoing work with Hong Liu, we use closed string field theory (CSFT) to bring these ideas to a test. Building on the recent boundary–covariant formulation by Carlo Maccaferri et al https://inspirehep.net/literature/2931466, we compute the classical on–shell action and use it to define a state on a Cauchy slice in Rindler space; we then further split this state to construct a reduced density matrix. Our preliminary results indicate the presence of edge modes localized on the codimension–two entangling surface in CSFT. These tree–level degrees of freedom are natural candidates to account for the Bekenstein–Hawking entropy at the classical level. The near–term goal is to compute the von Neumann entropy in this framework directly (not using the replica trick) and test, directly within CSFT, whether the entanglement entropy is UV finite.
Title: Towards an Algebra of Observables in String Theory
Speaker: Amr Ahmadain
Abstract: It is widely believed that string theory cures the ultraviolet divergences of entanglement entropy that arise in local QFTs, and that the classical entropy of very non–extremal black holes admits a statistical interpretation in a consistent quantum theory of gravity. In ongoing work with Hong Liu, we use closed string field theory (CSFT) to bring these ideas to a test. Building on the recent boundary–covariant formulation by Carlo Maccaferri et al https://inspirehep.net/literature/2931466, we compute the classical on–shell action and use it to define a state on a Cauchy slice in Rindler space; we then further split this state to construct a reduced density matrix. Our preliminary results indicate the presence of edge modes localized on the codimension–two entangling surface in CSFT. These tree–level degrees of freedom are natural candidates to account for the Bekenstein–Hawking entropy at the classical level. The near–term goal is to compute the von Neumann entropy in this framework directly (not using the replica trick) and test, directly within CSFT, whether the entanglement entropy is UV finite.
Workshop: Silvia Georgescu
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title: Conformal boundaries near cosmological horizons
Speaker: Silvia Georgescu
Abstract: TBA
Title: Conformal boundaries near cosmological horizons
Speaker: Silvia Georgescu
Abstract: TBA
Workshop: Tom Hartman
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Gravity on a finite region with fixed-area boundary conditions
Speaker: Tom Hartman
Abstract: Gravity can be formulated on a finite region of Euclidean spacetime, with boundary conditions that fix the areas or bending angles at extremal surfaces on the boundary. The path integral with these boundary conditions computes the statistics of black hole operators. I will discuss this approach in general dimensions, and then focus on the semiclassical geometries in 3D gravity with negative cosmological constant, which are built from generalized hyperbolic tetrahedra. These are the geometries underlying recent topological calculations in Virasoro TQFT and Conformal Turaev-Viro theory.
Title: Gravity on a finite region with fixed-area boundary conditions
Speaker: Tom Hartman
Abstract: Gravity can be formulated on a finite region of Euclidean spacetime, with boundary conditions that fix the areas or bending angles at extremal surfaces on the boundary. The path integral with these boundary conditions computes the statistics of black hole operators. I will discuss this approach in general dimensions, and then focus on the semiclassical geometries in 3D gravity with negative cosmological constant, which are built from generalized hyperbolic tetrahedra. These are the geometries underlying recent topological calculations in Virasoro TQFT and Conformal Turaev-Viro theory.
Workshop: Aron Wall
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: Towards Hamiltonian String Field Theory, and Dirichlet Walls
Speaker: Aron Wall
Abstract: I will present preliminary work towards formulating string field theory in a Hamiltonian (equal time slice) formalism. This problem is closely related (via a Wick rotation) to the problem of finding consistent End-Of-The-World boundary conditions for string scattering, in which the metric satisfies Dirichlet boundary conditions (rather than Neumann). In defining the transition amplitudes, two fundamental problems arise: (i) string worldsheets have tadpoles which transgress across the boundary infinitely often, and (ii) when a string does cross the boundary, it can cross multiple times. However, I believe that both of these problems can be overcome (at least at tree level) by clever resummation tricks.
Title: Towards Hamiltonian String Field Theory, and Dirichlet Walls
Speaker: Aron Wall
Abstract: I will present preliminary work towards formulating string field theory in a Hamiltonian (equal time slice) formalism. This problem is closely related (via a Wick rotation) to the problem of finding consistent End-Of-The-World boundary conditions for string scattering, in which the metric satisfies Dirichlet boundary conditions (rather than Neumann). In defining the transition amplitudes, two fundamental problems arise: (i) string worldsheets have tadpoles which transgress across the boundary infinitely often, and (ii) when a string does cross the boundary, it can cross multiple times. However, I believe that both of these problems can be overcome (at least at tree level) by clever resummation tricks.
Friday, December 12th, 2025
Workshop: Vahid Taghiloo (Zoom)
Time: 9:30 AM - 10:30 AM
Location: SCGP 102/ZOOM
Title: Gravity Is Induced By Renormalization Group Flow
Speaker: Vahid Taghiloo
Abstract: In this talk, we study the renormalization group (RG) flow of a holographic CFT in the AdS5/CFT4 framework. Moving from the UV toward the IR along the RG trajectory of the boundary theory, we find that gravitational couplings are gradually generated, giving rise to a dynamical boundary gravity. This surprising result suggests that gravity can emerge dynamically in the infrared rather than being a fundamental interaction.
Title: Gravity Is Induced By Renormalization Group Flow
Speaker: Vahid Taghiloo
Abstract: In this talk, we study the renormalization group (RG) flow of a holographic CFT in the AdS5/CFT4 framework. Moving from the UV toward the IR along the RG trajectory of the boundary theory, we find that gravitational couplings are gradually generated, giving rise to a dynamical boundary gravity. This surprising result suggests that gravity can emerge dynamically in the infrared rather than being a fundamental interaction.
Workshop: Albert Law
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title: Horizon Edge Modes in Λ > 0 Quantum Gravity
Speaker: Albert Law
Abstract: We derive the explicit form of the induced boundary gravitational action in the IR regime. The resulting effective theory includes Einstein gravity with a cosmological constant, supplemented by a single higher-derivative correction in the form of a Weyl-squared term. This provides a concrete realization of gravity emerging from holographic renormalization group flow.
Title: Horizon Edge Modes in Λ > 0 Quantum Gravity
Speaker: Albert Law
Abstract: We derive the explicit form of the induced boundary gravitational action in the IR regime. The resulting effective theory includes Einstein gravity with a cosmological constant, supplemented by a single higher-derivative correction in the form of a Weyl-squared term. This provides a concrete realization of gravity emerging from holographic renormalization group flow.
Workshop: Celine Zwikel
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Covariant Phase Space for Boundaries with Corners: An Example of AdS$_4$ in Partial Bondi Gauge
Speaker: Celine Zwikel
Abstract: In this talk, I will review the covariant phase space method for deriving charges associated with residual symmetries. I will focus on boundaries that can be leaky and feature corners, such as a wedge of AdS$_4$. Using the Partial Bondi Gauge to probe the asymptotic boundary, I will show that the presence of corners allows for additional charges, such as Weyl charges, beyond the usual Brown-York charges. This example illustrates how more relaxed gauge and boundary conditions can enrich the structure of the phase space. Based on arXiv:2512.03170.
Title: Covariant Phase Space for Boundaries with Corners: An Example of AdS$_4$ in Partial Bondi Gauge
Speaker: Celine Zwikel
Abstract: In this talk, I will review the covariant phase space method for deriving charges associated with residual symmetries. I will focus on boundaries that can be leaky and feature corners, such as a wedge of AdS$_4$. Using the Partial Bondi Gauge to probe the asymptotic boundary, I will show that the presence of corners allows for additional charges, such as Weyl charges, beyond the usual Brown-York charges. This example illustrates how more relaxed gauge and boundary conditions can enrich the structure of the phase space. Based on arXiv:2512.03170.
Workshop: Adam Levine
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: A modern path integral approach to closed universes and the no-boundary proposal
Speaker: Adam Levine
Abstract: From the modern perspective, there are two ways of interpreting the GPI. The first option is that the GPI computes an average over an ensemble of theories, from which properties of members of the ensemble can be inferred statistically. Within this approach, we review that the Hilbert space of closed universes is one-dimensional, consistent with recent general arguments, and we discuss a proposal that including an observer can cure the one-dimensionality problem for closed universes. The second option is that the GPI computes inner products in the Hilbert space of closed universes constructed by Marolf and Maxfield. This Hilbert space need not be trivial. Nevertheless, we find that the transition probabilities between the no-boundary state and simple closed universe states specified by local boundary conditions on a slice is $1$ up to non-perturbative corrections in $1/G_N$. Furthermore, we emphasize that observables which might reasonably be called single-closed-universe observables are not necessarily super-selected into \alpha sectors, consistent with ideas from upcoming work by Maxfield, Stanford and Yang.
Title: A modern path integral approach to closed universes and the no-boundary proposal
Speaker: Adam Levine
Abstract: From the modern perspective, there are two ways of interpreting the GPI. The first option is that the GPI computes an average over an ensemble of theories, from which properties of members of the ensemble can be inferred statistically. Within this approach, we review that the Hilbert space of closed universes is one-dimensional, consistent with recent general arguments, and we discuss a proposal that including an observer can cure the one-dimensionality problem for closed universes. The second option is that the GPI computes inner products in the Hilbert space of closed universes constructed by Marolf and Maxfield. This Hilbert space need not be trivial. Nevertheless, we find that the transition probabilities between the no-boundary state and simple closed universe states specified by local boundary conditions on a slice is $1$ up to non-perturbative corrections in $1/G_N$. Furthermore, we emphasize that observables which might reasonably be called single-closed-universe observables are not necessarily super-selected into \alpha sectors, consistent with ideas from upcoming work by Maxfield, Stanford and Yang.