Format results
-
Null Musings
Luca Ciambelli - Perimeter Institute for Theoretical Physics
-
-
Quantum Geometry of the Light Cone
Wolfgang Wieland - University of Erlangen-Nuremberg
-
-
-
Spectral Density of the Causal Propagator
Yasaman Kouchekzadeh Yazdi - Dublin Institute For Advanced Studies
-
An algebra of proper observables at null infinity: Dirac brackets, Memory and Goldstone probes
Rodrigo Andrade E Silva - Perimeter Institute for Theoretical Physics
-
-
-
Comments on overlaps in de Sitter gravity and the no-boundary state
Kristan Jensen - University of Victoria
-
From UV completeness to black hole physics: lessons from Hořava Gravity and Asymptotic Safety
Francesco Del Porro - University of Copenhagen
-
How to count states in gravity
Vijay Balasubramanian
-
Null Musings
Luca Ciambelli - Perimeter Institute for Theoretical Physics
One of the main achievements of my last four years at Perimeter has been the development and formulation of intrinsic null geometry. This framework has served as a common denominator for the study of the (algebraic) quantization of gravity on null hypersurfaces; connections to quantum-gravity… -
Canonical Quantization of Singular Configuration Spaces: Symmetry Reduction, Mass Gap Bounds, and Non-smooth Calculus
Luca Mrini - University of Vienna
In this work-in-progress, we study the quantization of singular configuration spaces, generalizing the canonical structures of smooth quantum mechanics. We develop a framework for constructing a Hilbert space of quantum states, generalized position and momentum operators, a kinetic-plus-potential… -
Quantum Geometry of the Light Cone
Wolfgang Wieland - University of Erlangen-Nuremberg
In Einstein's theory of general relativity, the causal structure of spacetime is itself dynamical. Causality is encoded into the geometry of light cones that bend under the influence of gravity. Quantum theory, on the other hand, tells us that nature is intrinsically probabilistic. A sharply defined… -
Mixed-helicity sector of celestial symmetries and the shadow transform
Domenico Giuseppe Salluce - University of Udine
The asymptotic symmetries of null infinity in asymptotically flat spacetimes can be enhanced to a w1+∞ algebra, when restricting to a single graviton helicity sector. These symmetries were first extracted from the operator product expansion (OPE) of conformal gravitons in celestial holography. They… -
The semiclassical energy outflux emerging from a collapsing shell
Noa Zilberman - Princeton
When a compact object collapses to form a black hole, quantum field theory predicts the emission of an energy outflux to future null infinity, which later relaxes to Hawking radiation. Within the semiclassical framework, we derive a simple, closed form, analytical expression for the energy outflux… -
Spectral Density of the Causal Propagator
Yasaman Kouchekzadeh Yazdi - Dublin Institute For Advanced Studies
In scalar quantum field theory, the causal propagator, which is proportional to the spacetime commutator of the field, plays an essential role. I will discuss some ways the causal propagator and its spectrum have been used to formulate quantum field theory in a more explicitly covariant manner in… -
An algebra of proper observables at null infinity: Dirac brackets, Memory and Goldstone probes
Rodrigo Andrade E Silva - Perimeter Institute for Theoretical Physics
The gravitational memory problem is typically phrased in terms of the failure of constructing a (separable) Hilbert space for radiative gravitational modes at null infinity containing distinct memory states. There is, in a sense, a classical version of this problem: so far, there is no completely… -
The gravitational S-matrix from the path integral: asymptotic symmetries and soft theorems
The classical action, or more generally the path integral, is a convenient framework for extracting the physical consequences of symmetries. In recent years, new symmetries of gravity in asymptotically flat spacetime have been uncovered based on relations to soft theorems governing the S-matrix. I… -
Can a multiverse theory explain the H_0 tension, the S_8 tension, the w(z) < -1 behavior and many other cosmological observations? Maybe!
Jan Ambjorn - University of Copenhagen
A simple multiverse model explains the late time exponential expansion of our universe without the need of a cosmological constant. Assuming that the local measurement of H_0 is correct, it also give a better fit to data than the standard LCDM model, as well as a z-dependent state parameter w(z)… -
Comments on overlaps in de Sitter gravity and the no-boundary state
Kristan Jensen - University of Victoria
I will discuss some aspects of quantum mechanics at late time in de Sitter space, focusing on the norm of the no-boundary state in semiclassical gravity. -
From UV completeness to black hole physics: lessons from Hořava Gravity and Asymptotic Safety
Francesco Del Porro - University of Copenhagen
In the search for a consistent and renormalizable quantum theory of gravity, a conservative possibility is that gravity admits a field-theoretic description valid up to arbitrarily high energies. This amounts to going beyond the perturbative non-renormalizability of general relativity and it can be… -
How to count states in gravity
Vijay Balasubramanian
Gibbons and Hawking proposed that the Euclidean gravity path integral with periodic boundary conditions in time computes the thermal partition sum of gravity. As a corollary, they argued that a derivative of the associated free energy with respect to the Euclidean time period computes gravitational…
